Apple 12-600PS, 12 660PS Service manual

Download

Page 1

Color LaserWriter 12/600 PS and 12/660 PS Service Technical Documentation

Steve Rancourt 5/95

This document was created with FrameMaker 4.0.4

Page 2

About Graphics

Using the magniﬁer tool enables you to zoom

Thumbnails

Bookmarks

Could not open the speciﬁed ﬁle...

If you get this message when trying to launch a QuickTime movie, you may not have enough memory to run MoviePlayer. Try quitting out of other applications.

This error also may occur if you copied ﬁles from the CD to a hard drive and have not foldered the ﬁles identically to the arrangement of folders on the CD.

into graphics and see greater detail.

About Printing

pages out of Acrobat. Page numbers that appear on the paper do not reﬂect their true order within the document.

Always use these numbers when printing

Page 3

Service Source

Color LaserWriter

Color LaserWriter 12/600 PS Color LaserWriter 12/660 PS

Page 4

Color LaserWriter 12/660 PS

96.11.13.15.58

Page 5

Color LaserWriter 12/660 PS 3–2

Overview

The Color LaserWriter 12/660 PS is an enhanced version of the original Color LaserWriter 12/600 PS. The 12/660 engine and plastics are identical to the original in every respect, and all ﬁnished goods and service part numbers apply equally to both printers. The sole differences between the two versions are in the packaging and setup, the ROM and RAM on the I/O controller board, and the driver software.

Packaging and Setup Changes

The Color LaserWriter 12/660 PS requires two extra steps during setup, the leveling of the printer and the removal of oil absorption sheets from the fuser assembly.

Note

: The orange ﬂag that identiﬁes the shipping screw has

also been enlarged in the new version of the printer. The leveling procedure helps to alle viate oil o v erﬂow problems

within the fuser assembly. The level and shim kit that comes with the 12/660 PS is also available separately as P/N 076-0622 for those who would to perform the procedure on the original version of the printer. After removing the packing tape from the outside of the printer, performing the leveling procedure below before proceeding any further.

1 Remove the spirit level and the round black rubber shims from

their package. Snap the spirit level into its base.

2 Open the printer’s top access cover and place the spirit level on

top of the fuser to level the printer , ﬁrst from front-to-back, then from side-to-side.

Spirit Level

96.11.13.15.58

Page 6

Color LaserWriter 12/660 PS 3–3

3 Place the shims under the printer’s feet (as needed) to level the

printer.

Shim

The oil absorption sheets have been installed to eliminate migration of silicon oil during shipping. After leveling the printer, remove the shipping spacers and absorption sheets as described below.

1 Open the fuser access door and remove the two orange spacers

and the oil absorption sheet from inside.

96.11.13.15.58

Page 7

Color LaserWriter 12/660 PS 3–4

2 Open the fuser assembly and remove the oil absorption sheet

from the inside of the fuser assembly.

I/O Controller Board Changes

Driver Software

The Color LaserWriter 12/660 PS comes standard with 16 MB of DRAM and version 2.0 of ROM. All other characteristics of the board remain the same.

Note

: Version 2.0 of ROM contains ﬁxes for variety of system and networking bugs that have been reported since the release of the original printer. (I/O controllers with 2.0 ROM will also output new startup and demo pages). If you want to upgrade an existing printer, see “Upgrade Path” later in this chapter.

The new version of the Color LaserWriter printer does not require a driver upgrade. However, the printer name has changed in ROM. Consequently, with older drivers you must manually select the “LaserWriter Color 12/600 PS” PPD when setting up the new printer in the Chooser.

Alternately, if copy the new “LaserWriter Color 12/660 PS” PPD into the Printer Descriptions folder (path: System Folder:Extensions folder), Chooser setup will be automatic. This PPD can be found on the Service Source CD (path: Service Manuals:Clips:CLW 12/660 PPD).

96.11.13.15.58

Page 8

Color LaserWriter 12/660 PS 3–5

Upgrade Path

You can upgrade a Color LaserWriter 12/600 PS to a Color LaserWriter 12/660 PS by installing version 2.0 ROMs onto the customer’s I/O controller board. The version 2.0 R OM upgrade kit is available as P/N 076-0621. The contains eight ROM ICs, a user manual addendum, a software installation CD, and upgrade labels.

Note

: Install new ROM only if the customer’s printer is exhibiting one of the problems described below. Install a replacement I/O controller board (P/N 661-0133) only if your troubleshooting has found the board to be defective. All service stock for the I/O controller board will include version 2.0 of ROM.

After installing the new R OM, afﬁx the labels that are provided in the kit as described in the instructions that accompany the ROM upgrade kit.

Feature added in ROM v2.0

System bugs ﬁxes in ROM v1.2

Caution:

of the ROM also appeared in version 1.2.

All but one of the bug ﬁxes contained in version 2.0

If your I/O

controller board has version 1.2 of ROM, do not upgrade

unless it is speciﬁcally for the Windows 95 feature described immediately below. You can identify the ROM version by inspecting the margin text on the startup page.

• Plug and play support for Windows 95 Plug and play support means that the user can connect the

printer to the system, boot Windows 95, and automatically see the printer name in the “New Hardware Found” dialog box during the installation process. After installation is complete, the Device ID string and related information will be returned whenever the printer is queried for its device id.

• System error at address 0x132460 When printing a complex document to the Color LaserWriter

12/600 PS, a page is printed stating “printer restarted due to system error at address 0x132460.”

• System error at address @0x33F844 A bug in version 1.0 ROM caused certain complex Adobe Illus-

trator ﬁles to reset the printer and to print a page stating “printer restarted due to system error at address @0x33F844.

• Image stitching problem When an image has a very ﬁne line running across its body and

the line does not seem to belong to the image, that may be a stitching problem. If the same problem occurs when printing to another printer, for example a LaserWriter 16/600 PS, the

96.11.13.15.58

Page 9

Color LaserWriter 12/660 PS 3–6

problem is likely in the application and the ROM upgrade will not help.

If possible, try printing the problem ﬁle to a printer with version

2.0 ROMs. If there is no improvement, then the problem is elsewhere.

• NetWare port number not set properly When setting the NetWare port number through the Apple

Printer Utility, the number did not stick.

• Changing AppleTalk type fails Changing the AppleTalk “type” on version 1.0 ROMs fails

when PAPTest is run through a LocalTalk port. (Unlikely to affect normal user).

• EtherTalkZone and LocalTalkType strings EtherTalkZone strings and LocalTalkType strings did not take

input longer than 31 characters. (Unlikely to affect normal user).

• LocalTalk ports turns off; EtherTalk remains active In some cases, the LocalTalk port turned off after printing a

very large number of PostScript test ﬁles to a printer using both EtherTalk & LocalTalk ports, even though the EtherTalk port remained active and could be seen from any host. (Unlikely to affect normal user).

• Speciﬁc PostScript Code resets printer Sending the following PostScript code caused the printer to

reset itself (unlikely to affect normal user):

[(%disk1%) <</InitializeAction 1>> setdevparams]

• PowerPoint v3.0 gradients Some PowerPoint slides containing complex gradients or

patterns would freeze the printer.

• TraySwitch not saved Enabling the TraySwitch feature on a Color LaserWriter

12/600-J (Kanji version) did not survive power cycles.

• One-byte PostScript ﬁlename on printer hard drive

Creating a one-byte long PostScript ﬁlename on a printer’s hard

disk caused an I/O error. (Unlikely to affect normal user).

• Conﬁguration switch and image data This issue only affects printing from PC computers using the

parallel port. Once the printer’s conﬁguration switch w as used,

96.11.13.15.58

Page 10

Color LaserWriter 12/660 PS 3–7

the default protocol for the parallel port (TBCP) was changed to Normal and not returned back to TBCP, regardless of conﬁguration switch position. In this scenario text documents would print, but documents with images (binary data) would not. The printer’s ready light would ﬂash for a while, stop, and then nothing would print.

Networking bugs ﬁxes in ROM v1.2

• NetWare polling If the printer was in NetWare PServer mode conﬁguration, it

would likely stop polling its NetWare print queue after being powered on for more than 24 hours.

• Name lengths increased The pserver and rprinter name length has been increased to 47

characters maximum.

96.11.13.15.58

Page 11

Color LaserWriter 12/660 PS 3–8

Installation Reimbursement Program

Beginning October 21, 1996, Authorized Apple Resellers and institutions are entitled to receive a $150 reimb ursement on the installation(s) of the Color Laserwriter 12/660 PS.

Customers who purchase the printer beginning October 21, 1996 are entitled to have the printer set up and installed in the location of their choice at their site.

How customers will be informed

A letter will be included with the printer informing customers to contact their Authorized Apple reseller, or Apple directly to perform the installation.

This letter also stipulates special tasks for the customer to perform before a service technician arrives at their location. These tasks include:

• Preparing a suitable location for the printer.

• Having someone available to help the service technician lift

the printer from the ﬂoor to the table or counter.

• Providing appropriate power, networking connections, and

cabling.

• Ensuring that a network administrator (or other knowledge-

able person) is available for consultation with the service technician.

• Providing a computer that is conﬁgured with the appropriate

system software and is functioning on the network.

• Arranging for the storage and disposal of packing materials.

Installation procedures

If everything is prepared, the service technician should be able to complete the setup and installation in about 45 minutes.

The ﬁle “CLW 12/660 Setup.pdf” is the ﬁrst chapter of the Color LaserWriter 12/660 PS. Read this chapter for the special considerations required when setting up and installing this printer. Click on the icon below to open the ﬁle.

96.11.13.15.58

Page 12

Basics and Theory

Page 13

Color LaserWriter 12/600 PS Basics & Theory 1–2

Chapter Contents

I General Information

Features ......................................................................................................... 1–5

Speciﬁcations..................................................................................................1– 6

Safety Information ..........................................................................................1–10

Laser Safety ..............................................................................................1–10

Toner Safety .............................................................................................. 1–10

Ozone Safety ............................................................................................ 1–10

Status Panel ................................................................................................... 1–11

Outline .......................................................................................................1–11

Conﬁgurations ...........................................................................................1–12

Density Control Panel ....................................................................................1–13

Panel Layout .............................................................................................1–13

Density Adjustments .................................................................................1–14

Test Page Pattern Selection.......................................................................1–15

Separation Voltage Designation ................................................................1–16

Registration Adjustments........................................................................... 1–17

II Basic Operation

Paper Path Animation..................................................................................... 1–19

Functions ........................................................................................................1–20

Outline of Electrical System ........................................................................... 1–21

Outline of Major Circuit Boards ...................................................................... 1–22

DC Controller Input/Output Signals ...........................................................1–23

Mechanical Controller Board Input/Output Signals ...................................1–26

Outline of Drive System .................................................................................1–28

III Laser/Scanner System

Laser System ................................................................................................. 1–32

Scanner System ............................................................................................. 1–38

IV Image Formation System

Outline ............................................................................................................1–41

Photoconductor Cartridge .............................................................................. 1–43

Toner Cartridge ..............................................................................................1–44

Stages of Imaging .......................................................................................... 1–47

Stage 1: Electrostatic Latent Image Formation ........................................1–48

Stage 2: Developing .................................................................................1–50

Stage 3: Photosensitive Drum Cleaning .................................................. 1–51

Stage 4: Transfer ..................................................................................... 1–53

Stage 5: Transfer Drum Cleaning and Discharge ....................................1–57

Stage 6: Fusing ........................................................................................1–59

High-Voltage Control ...................................................................................... 1–60

Photosensitive Drum Life Detection ...............................................................1–68

Toner Carousel Control ..................................................................................1–71

Toner Cartridge Installation .......................................................................1–73

Carousel Rotation...................................................................................... 1–75

Toner Cartridge Stop.................................................................................. 1–79

Toner Cartridge Press ...............................................................................1–80

Developing Cylinder Drive ........................................................................1–81

Toner Cartridge Separation ....................................................................... 1–82

Image Quality Stability Control ....................................................................... 1–84

Temperature/Humidity Sensing System .................................................... 1–85

Density Calibration System .......................................................................1–86

95.08.23.11.28

Page 14

Color LaserWriter 12/600 PS Basics & Theory 1–3

V Pickup/Feed System

Outline ............................................................................................................1–89

Paper Pickup .................................................................................................. 1–90

Overhead Transparency Detection ................................................................1–96

Cassette Pickup Board ...................................................................................1–97

Transfer Drum and Peripherals ......................................................................1–100

Gripper Control .........................................................................................1–102

Attraction Roller ........................................................................................1–103

Separation .................................................................................................1–105

Transfer Drum Cleaning Assembly ...........................................................1–106

Discharge Roller .......................................................................................1–107

Cleaning Brush Motor Drive Circuit ...........................................................1–109

Fuser Assembly .............................................................................................. 1–110

Transparency Mode ..................................................................................1–112

Fuser Assembly Errors ..............................................................................1–115

Oil Circulation System ...............................................................................1–122

Fuser Cleaner Assembly ...........................................................................1–124

Main Motor Drive Circuit .................................................................................1–125

Paper Jam Detection ......................................................................................1–126

Pickup Delay Jam ..................................................................................... 1–127

Paper Top Position Delay Jam .................................................................. 1–128

Grip Jam ...................................................................................................1–129

Separation Delay Jam ...............................................................................1–130

Separation Stationary Jam ........................................................................1–131

Delivery Delay Jam ...................................................................................1–132

Delivery Stationary Jam ............................................................................1–133

Multi-Fed Paper Stationary Jam ...............................................................1–134

Non-Dedicated Transparency Jam ...........................................................1–135

Wrong Paper Length Feed Jam ................................................................1–136

Initial Residual Jam ...................................................................................1–137

VI System Interface

Outline ............................................................................................................1–139

Video Interface ...............................................................................................1–140

VII Power Supply

Outline ............................................................................................................1–143

Remote Switch ...............................................................................................1–145

VIIISheet Feeder

Outline of Electrical Circuit .............................................................................1–147

Sheet Feeder Controller Board Input/Output .................................................1–148

Pickup/Feed System ...................................................................................... 1–149

Power Supply .................................................................................................1–150

95.08.23.11.28

Page 15

Color LaserWriter 12/600 PS Basics & Theory 1–4

I. General Information

Page 16

Color LaserWriter 12/600 PS Basics & Theory 1–5

Features

Some of the main features of the Color LaserWriter 12/600 PS are as follows:

Print Quality

Speed

Multiplatform Support

Connectivity Automatic

Trafﬁc Control

Fonts

Energy Savings

Hard Disk Option

The printer has a resolution of 600x600 dots per inch, with color PhotoGrade.

The printer prints up to 12 pages per minute in black, cyan, magenta, or yellow; 3 pages per minute in two or more colors; and 1 transparency per minute.

You can connect the printer to Macintosh, Windows, DOS, and UNIX computers.

The printer offers LocalTalk, Ethernet, and parallel connections. Without any user intervention, the printer can accept jobs simulta-

neously from AppleTalk, TCP/IP, and NetWare networks and from the parallel port.

The printer supports both TrueType and PostScript fonts. The printer has 39 built-in PostScript fonts.

The printer can automatically lower its power consumption when it’s not being used.

You can install an internal hard disk or attach up to six external hard disks to store downloadable fonts.

Paper Handling

You can print up to 350 sheets (250 in the standard paper cassette plus 100 in the multipurpose tray) without changing paper. You can also add a 250-sheet feeder.

95.08.23.11.28

Page 17

Color LaserWriter 12/600 PS Basics & Theory 1–6

Speciﬁcations

Marking Engine

Laser

Controller

Canon HX LBP print engine

• 3 ppm in color; 12 ppm in black, cyan, magenta, or yellow; 1 ppm

for transparencies

• 600x600 dpi with Color PhotoGrade

• Enhanced 600 dpi grayscale imaging (effective 200-line screen half-

tone, 122 gray levels)

Semiconductor laser GaAlAs

• Wavelength: 780 nm

• Output power: 1 mW The speciﬁcations for the I/O controller board are as follows:

• AMD Am29030 30-MHz microprocessor

• 8 MB of ROM (including 39 Type 1 fonts)

• 12 MB of RAM (16 MB on CLW 12/660); 8 MB soldered + 4 MB

(or 8 MB) SIMM (expandable to 40 MB total)

• 128 K parameter SRAM

True 600 dpi

• SCSI interface for internal/external hard disk(s)

• LocalTalk interface

• High-speed parallel interface (IEEE P1284 ECP, bidirectional)

• Ethernet interface with three protocols: EtherTalk, Novell NetWare

IPX (PSERVER or RPRINTER), and TCP/IP (BSD lpd)

• External Ethernet transceivers a vailable for thin coaxial, twisted pair

(10Base-T), and thick coaxial (IEEE 802.3 AUI)

• Two-position communication conﬁguration switch

• All ports/protocols simultaneously active

• Color-rendering acceleration

• Data compression/decompression system

• Adobe PostScript Level 2 (version 2014) The Color LaserWriter 12/600 PS is a true 600 dpi printer because

every aspect of its architecture is designed to a 600 dpi speciﬁcation. In addition, its 8-bit per pixel capability can assign levels of color or gray to each pixel, thereby further enhancing print quality.

96.09.11.09.27

Page 18

Color LaserWriter 12/600 PS Basics & Theory 1–7

Printer Fonts

The following fonts are resident in the printer ROM:

• AvantGarde Book, AvantGarde BookOblique, AvantGarde Demi,

AvantGarde DemiOblique

• Bookman Demi, Bookman DemiItalic, Bookman Light, Bookman

LightItalic

• Courier, Courier Bold, Courier BoldOblique, Courier Oblique

• Helvetica, Helvetica Bold, Helvetica BoldOblique, Helvetica

Narrow, Helvetica Narrow Bold, Helvetica Narrow BoldOblique, Helvetica Narrow Oblique, Helvetica Oblique

• Helvetica Condensed, Helvetica Condensed Bold, Helvetica

Condensed BoldOblique, Helvetica Condensed Oblique

• NewCentury Schoolbook Bold, NewCentury Schoolbook Bold-

Italic, NewCentury Schoolbook Italic, NewCentury Schoolbook Roman

• Palatino Bold, Palatino BoldItalic, Palatino Italic, Palatino Roman

• Symbol

• Times Bold, Times BoldItalic, Times Italic, Times Roman

Life Expectancies

• Zapf Chancery MediumItalic

• Zapf Dingbats Minimum life expectancy for the printer is 5 years or 300,000 pages in

black and white or 150,000 color pages, with no monthly page limit. Recommended maintenance interval is 60,000 pages due to wear on fuser and rollers.

Toner Cartridge: 4,000 pages per color when printing documents with average page coverage of 5%.

Photoconductor cartridge: 40,000 pages black and white or 10,000 pages color (for continuous printing); 13,000 pages black and white or 6,500 pages color (printing only single-page documents).

Fuser oil life: 10,000 pages Fuser assembly life: 60,000 pages Transfer drum cleaner life: 60,000 pages Ozone ﬁlter life: 60,000 pages Air ﬁlter life: 60,000 pages Separation Discharge Assembly life: 60,000 pages

95.08.23.11.28

Page 19

Color LaserWriter 12/600 PS Basics & Theory 1–8

Speed

Printing Materials

Transparencies

Paper Sizes and Capacity

Safety Information

Laser Safety

The invisible laser beam irradiated within the laser/scanner assembly can be harmful if it comes into contact with your eyes. Consequently, never disassemble the laser/scanner assembly. A cautionary label has been afﬁxed to the top of the laser/scanner assembly.

Note

: The laser/scanner assembly cannot be adjusted in the ﬁeld, nor are any of its components available from Apple.

Toner Safety

Ozone Safety

Laser Safety Label

If you get toner on your skin or clothes, remove as much as possible with dry tissue and then wash with cold water. Do not let toner come into contact with vinyl material.

The charging roller and separation discharge assembly generate very small amounts of ozone gas when the printer is operating. The printer meets the Underwriters Laboratory (UL) ozone emission standard.

95.08.23.11.28

Page 22

Color LaserWriter 12/600 PS Basics & Theory 1–11

Status Panel

Outline

Movie

The Color LaserWriter 12/600 PS status panel consists of 4 primary and 17 secondary lights. The primary lights, arranged horizontally along the bottom of the panel, are similar to those on the LED panels on many of Apple’s previous printers.

During normal operation, primary lights report general readiness states for consumables, paper supply , and paper feed. Secondary lights report on speciﬁc consumables and highlight locations of a consumable, paper jam, or paper problems. The QuickTime movie to the left shows the normal operational behavior of the status panel when the printer starts up. See Chapter 2 for information on the Power-On Self Test (POST).

Access Lights Maintenance LightsToner Lights

Waste

Toner

Fuser

Assembly

Ready/In-Use

Light

Oil Photo-

conductor

Alert Light

Paper-Out

Light

Paper Jam

Light

95.08.23.11.28

Page 23

Color LaserWriter 12/600 PS Basics & Theory 1–12

= Flashing

Status Panel Lights

These are the possible arrays that customers can see during normal printer operation.

Description

Warming Up /Processing

Printer Ready

Low Magenta

Low Cyan

Low Yellow

Low Black

Low Fuser Assembly

Low Fuser Oil

Printer

Stops

500 pages later

50 pages later

Access

Lights

Photoconductor Warning

No Magenta Cartridge

No Cyan Cartridge

No Yellow Cartridge

No Black Cartridge

Toner Disposal Box Full

No Fuser Assembly

No Fuser Oil

No Photoconductor Cartridge

Door Open

(See "POST Code Matrix" in Chapter 2)

Yes

2 3

Access Lights

95.08.23.11.29

Page 24

Color LaserWriter 12/600 PS Basics & Theory 1–13

Density Control Panel

The density control panel on the rear of the printer can be used to generate a service test page and to set three distinct types of adjustments. Some adjustment settings are persistent (i.e., they will remain in effect after a printer restart), and some are nonpersistent (i.e., they will default to factory setting after a printer restart).

Panel Layout

In addition to the test print button, the density control panel has four toner-indicator lights along the top, an LED density gauge in the middle, and four input buttons along the bottom of the panel.

Toner Lights

Density Gauge

TEST PRINT

•

Important

M C Y Bk

COLOR

SELECT

DEFAULT ENTER

TEST

button: Press this button to generate a service test page.

: If the printer is in energy-saving mode, you must print to

the printer or restart the printer before you can run a service test page.

•

ENTER

Note

button: Engages the currently selected value.

: The next four items are labelled on the panel according to their density adjustment functions. During other adjustments, ignore the labels and the functions described below.

COLOR SELECT

•

button: Selects the color whose density you want to

adjust.

• Density gauge: Indicates the currently selected density value for the selected color, light density to the left, dark to the right.

Note

: During printer-ready state, you can tell if the density settings are not at the factory default by looking at the center density gauge LED above the word

DEFAULT

. If this LED is off, then the density settings

have been changed from the default.

5 Plus/minus (+/-) buttons: Advance the density gauge setting. 6 Toner Lights: An illuminated toner light indicates the color that is

being adjusted.

95.08.23.16.19

Page 25

Color LaserWriter 12/600 PS Basics & Theory 1–14

Density Adjustments

This feature is offered for customers who have multiple Color LaserWriter 12/600 PS printers in a single location and need to adjust one printer to match the output of another.

Important

: The range of settings is limited. Use this feature only if

you have prior experience in four-color density adjustments. The printer needs to be switched on and in a ready state to make density

adjustments. Density adjustments are persistent. To adjust the density,

1 Press the

COLOR SELECT

button as many times as necessary until the

desired toner light illuminates.

Selected Color

M C Y Bk

COLOR

SELECT

DEFAULT ENTER

TEST

2 Press the plus or minus button to change the setting for that color. The

density gauge LED will light whenever the selected setting differs from the previously entered setting.

3 Repeat steps 1 and 2 if you want to adjust other colors. 4 Press the

Note

: If you want to quickly return the printer to its factory defaults,

ENTER

button to engage the settings.

press and hold both the plus and minus buttons for at least ﬁve seconds.

95.08.23.11.29

Page 26

Color LaserWriter 12/600 PS Basics & Theory 1–15

Test Page Pattern Selection

This feature allows you to select one of six test page patterns based upon which one would best conﬁrm a print quality issue.

Test pattern selection is nonpersistent. After restart, the test page reverts to the vertical line pattern. To select a pattern,

1 Hold down the

COLOR SELECT

button and press the

ENTER

button eight times. The four toner lights will ﬂash to indicate that you are in the test pattern selection mode.

M C Y Bk

COLOR

SELECT

DEFAULT ENTER

TEST

2 Using the plus or minus buttons, advance the density gauge to illumi-

nate the LED corresponding to the desired pattern. The density gauge will ﬂash when the selected setting differs from the previously entered setting. Only LEDs 4 through 9 on the density gauge correspond to available patterns.

Usage Tips

Grid

3 Press the

Vertical

ENTER

Lines

GradationHorizontal

Solid

White

button to engage the setting. If you make no further

Solid

Colors

adjustments, the panel will exit from the test pattern selection mode in 30 seconds.

Each pattern will inherently reveal a different type of defect. For example, color registration problems are revealed best by the grid pattern, while dirty rollers are revealed by printing a solid white page.

Note

: By measuring the distance between repeating print defects, you can isolate the problem to a speciﬁc roller within the printer. See “Roller Diameters” in Chapter 2.

95.08.23.11.29

Page 27

Color LaserWriter 12/600 PS Basics & Theory 1–16

Separation Voltage Designation

This feature allows you to override the printer sensing system and force the separation discharge assembly on or off. Forcing-on is intended as a fail-safe in low temperature/low humidity conditions where paper is not properly separating from the transfer drum, and as a countermeasure in some image-offset problems. Forcing-off is a countermeasure against toner displacement.

The separation voltage designation is nonpersistent. After restart, the designation will revert to automatic. To designate the separation voltage,

1 Hold down the

COLOR SELECT button and press the ENTER button

three times. The yellow and black toner lights will ﬂash to indicate that you are in the separation voltage designation mode.

2 Using the plus or minus buttons, advance the density gauge to illumi-

nate the LED corresponding to the desired designation. The density gauge will ﬂash whenever the selected setting differs from the previously entered setting. Only LEDs 4, 5, and 6 on the density gauge correspond to available designations.

3 Press the

Separation Voltage Forced OFF Automatic (Separation Voltage

Determined by Sensing System) Separation Voltage Forced ON

ENTER button to engage the setting.

95.08.23.11.29

Page 28

Color LaserWriter 12/600 PS Basics & Theory 1–17

Registration Adjustments

This feature allows you to adjust the placement of the image area on the page. Registration adjustments require that the printer be placed into a service adjustment mode. Consequently, these adjustments are not designed to be available to end users. Registration adjustments are persistent. To adjust the registration,

1 Turn off the printer. Press and hold the

TEST PRINT button and switch

the printer back on. The normal startup sounds will not occur. Continue to hold the

TEST PRINT button down for 25 seconds, at which

time you will notice a slight slowing of the controller fan.

2 Press the

COLOR SELECT button once. The black toner light will ﬂash

to indicate that you are in the service adjustment mode. In addition, one of the other toner lights will illuminate steadily. Keep pressing the

COLOR SELECT button until you come to the setting that you want.

M C Y Bk

Leading Edge Registration Adjustment

Cassette Edge Registration Adjustment

Manual Feeding Tray Edge Registration Adjustment

3 Using the plus or minus buttons, advance the density gauge to illumi-

nate the LED corresponding to the desired adjustment value. For leading edge registration adjustment, each step in the gauge is equal to .012 inch (.3 mm). For the other two adjustments, each step in the gauge is equal to .017 inch (.425 mm).

4 Press the

ENTER button to engage the setting.

Note: If you want to quickly return the printer to its factory defaults, press and hold both the plus and minus buttons for at least ﬁve seconds.

95.08.23.11.29

Page 29

Color LaserWriter 12/600 PS Basics & Theory 1–18

II. Basic Operation

Page 30

Color LaserWriter 12/600 PS Basics & Theory 1–19

Paper Path Animation

The icon to the left appears at key points throughout this manual. Clicking it launches a QuickTime animation called “CLW Paper Path.”

Animation

This animation shows one complete print cycle through the Color LaserWriter 12/600 PS, starting at the point where the ﬁnal sheet of paper is picked up from the cassette, and ending with the delivery of the paper at the top of the printer.

Frame Number

Step BackPlay Step Forward

The animation is very detailed and moves very quickly. By using the “Step Back” and “Step Forward” buttons at the bottom right of the frame, you can step frame-by-frame through the animation. Whenever applicable, speciﬁc frame numbers that best illustrate a given topic are called out.

95.08.23.11.29

Page 31

Color LaserWriter 12/600 PS Basics & Theory 1–20

Functions

Printer functions can be divided into four systems: the overall control system, the image formation system, the laser/scanner system, and the paper pickup/feed system.

I/O Controller Board

I/O Interconnect Board

DC Controller Board

Laser/Scanner Assembly

Scanner

Motor

Laser Diode

Scanning Mirror

Beam

Position

Detector

Carousel

Primary

Charging

Roller

Toner

Overall Control System

Mechanical Controller Board

Face-Down Tray

Cleaning

Unit

Separation

Discharge

Assembly

Photo-

sensitive

Drum

Transfer Drum

External

Device

Paper Pickup/Feed System

Fuser

Assembly

Transfer Drum Cleaning Assembly

Face-

Delivery

Image Formation System

Attraction Roller

Cassette

Sheet Feeder (Optional)

Discharge Roller

Pickup

Block

Manual

Feed Tray

95.08.23.11.29

Page 32

Color LaserWriter 12/600 PS Basics & Theory 1–21

Outline of Electrical System

The operation sequence for the printer is controlled by the microcomputers on the DC controller and the mechanical controller boards. When the printer is turned on and enters the standby state, the microcomputer on the DC controller sends signals for driving the laser diode, fuser heaters, and other loads in response to the print signal entered from the I/O controller board. Simultaneously, the microcomputer on the DC controller sends the print sequence command to the microcomputer on the mechanical controller. Subsequently, the latter microcomputer outputs the signals for driving various loads, including the highvoltage power supply, motors, and solenoids.

External Device

I/O Controller Board

I/O Interconnect Board

Density Sensing Board

Cassette

Size-Sensing

Board

Laser/Scanner Assembly

Scanner Motor

Beam-Detect Board

Laser Driver Board

Various Sensors

Status Panel

Ejection Sensing

Board

DC Controller

Board

High-Voltage

Power Supply

Mechanical

Controller

Board

Power Supply

Low-Voltage

Power Supply

Primary Charging Roller Developing Bias Transfer Charging Roller Attraction Roller

Discharge Roller Separation Discharge

Upper Fuser Roller

Pickup Motor

Cassette Pickup Board

Sensors/Solenoids/Clutches

Main Motor Drum Motor Toner Carousel Motor

Cleaning Brush Motor Various Fan Motors

Various Sensor/ Solenoids/Clutches

Temperature/Humidity Sensor Board

Toner Sensor

Main Switch

AC Drive Circuit

Fuser Heaters (Upper/Lower)

95.08.23.11.29

Page 33

Color LaserWriter 12/600 PS Basics & Theory 1–22

Outline of Major Circuit Boards

This section describes the functions of the DC controller board and the mechanical controller board. See “Circuit Boards” in the Parts chapter for additional information.

DC Controller Board

Mechanical Controller Board

This board controls the printer. When the

/PRNT signal is received from

the I/O controller, the DC controller sends the print sequence command to the mechanical controller, which then starts controlling various loads. The DC controller also provides

• Laser/scanner control

• Image stabilization control

• Fuser temperature control

• Power-off time measurement

• Various detection functions

• I/O interface control

This board controls various loads in response to signals from the DC controller board. The mechanical controller returns the status signals to the DC controller. The mechanical controller controls the cassette pickup board, the high-voltage power supply, and the sheet feeder controller board via its serial communications. The mechanical controller also provides

• Drive of various motors and fan motors

• Control of the toner carousel

• Control of the fuser assembly

• Control of the transfer drum and its peripheral assemblies

• Control of the cassette pickup board, the high-voltage power supply ,

and the sheet feeder controller board

• Toner stirring function, toner-low detection, and toner cartridge

detection

• Photosensitive drum life detection

• Waste toner collection system control

• Energy-saving mode control

95.08.23.11.29

Page 34

Color LaserWriter 12/600 PS Basics & Theory 1–23

DC Controller Input/Output Signals

Laser/Scanner Assembly DC Controller Board

J111-23

Laser

Control

Board

-22

-17

-1,-3,-4,-5,

-6,-7,-13,15

-9

/VDOENB /LSON NHD SCK1

M1 to M8

"L" when video data can be written. "L" to switch ON the laser diode forcibly. Reset signal Clock signal

PWM mode-setting signal

-11 Analog signals are output to control

the laser power. Voltage is input in proportion to the

laser power. Video data signals

Laser Diode

J110-7

-5

-11,-13,-15,-17,

-19,-21,-23,-25

-9

LLCNT PDIN

Dv2 to Dv9

+5V

J102-4

-3

-2

/BDI

"L" when the BD signal is input.

Beam-Detect

Board

J451-1

-2

-3

+24V

J102-10,-11

-6

-8

-9

-5,-7

SCNCLK /SCNON /SCNRDY

Reference clock signal "L" to drive the scanner motor.

"L" when the scanner motor is rotating normally.

Scanner

Motor

J701-1,-2

-6

-4

-3

-5,-7

Oil-Low Sensor

PS13

Cleaning Belt

Sensor

PS5

Transfer Drum

Top Sensor

PS8

Waste Toner

Sensor

PS12

Cassette

Size-Sensing Switch

CSW3 CSW2 CSW1

J312-1

-2

-3

-4

J61-3

Sensing Switch

J1602-4

-3

-2

-1

J631-3

-1

-2

J41F-1

-3

-2

J631-3

-1

-2

Ejection

SW1601

-1

-2

J106-6

J106-1

J105-13

J1601-1

-5

-4

-3

-2

-11

-12

J107-1

J107-7

-2

-3

-4

-3

-2

-6

-5

-4

OILSNS

LEDON

WEBSNS

+5V

TOPREG

LEDON TNFUL

/CSIZE3 /CSIZE2 /CSIZE1

"H" when oil runs out.

"L" when the power-saving mode is set. "H" when the cleaning belt has run out.

"H" switched to "L" when the TOP position of the transfer drum is detected. "L" switched to "H" when the registration position is detected.

"L" when the power-saving mode is set. "H" when the waste toner is full.

The cassette size and the pulling operation for the ejector are detected.

95.08.23.11.29

Page 35

Color LaserWriter 12/600 PS Basics & Theory 1–24

DC Controller Board

Power Supply

Power

Switch

SW1 Door

Switch

SW2

Power Supply Control IC

Fuser Abnormality

Detection Circuit

Safety Circuit

+24V

+5V

Relay

+5V

Mechanical

Controller

Board

J101-6

J112-31

-30

-29

-28

-26

-27

-5

-7

POFF PCONT

DOPN

FXSTS

SFSNS /FXROF /FXENB

/FXUON /FXLON

"L" when the power switch is ON.

"L" to turn ON the printer. "H" when the front door,

pickup door, or fuser access door is open.

"L" when the fuser assembly is properly installed; "H" when improperly installed; pulse signal when fuser heater is ON.

"H" when the safety circuit turns OFF the relay.

"L" to turn OFF the relay. The fuser heater can be

turned ON when pulses are output.

"L" to turn ON the upper fuser heater.

"L" to turn ON the lower fuser heater.

Thermoswitch

TP1

Thermoswitch

TP2

Fuser Roller Temperature Detection

Fuser Assembly

Upper

Fuser Heater

Lower

Fuser Heater

Thermistor

J112-24

J112-22

The voltage decreases as the fuser roller

THI

temperature increases.

/FXSNS

"L" when the fixing unit is installed.

95.08.23.11.29

Page 36

Color LaserWriter 12/600 PS Basics & Theory 1–25

DC Controller Board

Temperature/

Humidity Sensor

J73-1

-3,-5

-2

-4

J2005-5

-4

-2

-1,-3

Mechanical

Controller Board

J2007-6

-7

-9

-8,-10

J112-6

-8,-10

-7

HUMSNS

-9 TMPSNS

+5V

Humidity sensor signal Temperature sensor signal

Density Sensing

Board

Density Control

Panel

J103-14

-3

-5,-6,-7,-8,-9,-10,-11,-12

-13

J114-1 to 8

+24V +5V

-1

-2

DSNS /DSEL

Density sensor signal "H" to enter the color toner

density sensing mode. "L" to enter the black toner density sensing mode.

/D0 to /D7

/DENB

-4

LED power control signal "L" to turn ON the LED.

Serial Communications

95.08.23.11.29

Page 37

Color LaserWriter 12/600 PS Basics & Theory 1–26

Mechanical Controller Board Input/Output Signals

Mechanical Controller Board

High-Voltage Power Supply

Cassette Pickup Board

Toner Carousel Sensors

Toner

PS4

Carousel Position Sensor

Toner

PS3

Cartridge Position Sensor

CL2 Toner Carousel Drive Clutch

CL1 Toner Carousel Brake Clutch

Fuser Assembly

PS10

Oil Overflow Sensor

J2008

J2002

J2006-4

-6

-5

J2006-1

-3

-2

J2017-4

-3

J2017-2

-1

J2009-12

-14

-13

Serial Communications

5VSAVE

DEVHP

"H" when a flag is detected. See "Carousel Rotational Detection" in this chapter.

5VSAVE

"L" when the toner cartridge is pressed

DEVCAM

against the photosensitive drum. "H" when the toner cartridge is separated from the photosensitive drum.

+24V

/DEVON

"L" to turn ON CL2, rotating the toner carousel

"H" to turn OFF CL2, rotating the cartridge sleeve.

+24V

/DEVBRK

"L" to turn ON CL1, braking the toner carousel.

5VSAVE

OILFUL

"H" when oil overflows from oil pan.

Paper Delivery Sensor

Fuser Assembly Drive Clutch

Cleaning Belt Drive Solenoid

Attraction Roller Press Solenoid

Drum Press Solenoid

Transfer Drum Cleaner Press Solenoid

Discharge Roller Press Solenoid

PS9

CL4

SL3

SL6

SL7

SL8

SL9

J2009-9

-11

-10

J2011-2

J2009-8

J2014-2

J2014-4

J2014-5

J2014-10

POUT

+24V

-1

/FIXON

+24V

-7

/WEBSL

+24V

-1

/ATTSLON

+24V

-3

/DDSLON

+24V

-6

/TDCSLON

+24V

-9

/DCSLON

5VSAVE

"H" when paper is detected.

"L" to turn ON SL3, rotating the rollers in the fuser assembly.

"L" to turn ON SL12. This solenoid is used to drive the cleaning belt.

"L" to turn ON SL6, operating the attraction roller press cam. SL6 is used to control the pressing/separation between the attraction roller and the transfer drum.

"L" to turn ON SL7, operating the transfer drum press cam. SL7 is used to control the pressing/separation between the photosensitive drum and the transfer drum.

"L" to turn ON SL8, operating the cleaning brush press cam. SL8 is used to control the pressing/separation between the cleaning brush and the transfer drum.

"L" to turn ON SL9, operating the discharge roller press cam. SL9 is used to control the pressing/separation between the discharge roller and the transfer drum.

95.08.23.11.29

Page 38

Color LaserWriter 12/600 PS Basics & Theory 1–27

Transfer Drum

PS6

Attraction Sensor

PS8

Transfer Drum

Top Sensor

PS7

Separation Sensor

Gripper Drive Solenoid

Separation Solenoid

SL4

SL5

Receiver Emitter

Toner Sensor PS11

Main Motor

Toner Carousel Motor

Drum Motor

Cleaning Brush Motor

Fuser Fan Motor

DC Controller Board

J105

-3

-11

-8

-4

-10

-5

-2

J112

-20

-19

-18

-4

-17

-16

FM1

J2007

-12

-13

-14

-15

-28

-16

J2007-21

J2017-5

J2013-6

J2016-1

J2015-1

J2014-8

-7

J2012-3

-2

-1

ATTSNS

TOPREG

SEPSNS

TNSNS

+5V

-6

-7

-1

MLOW

-2

/MRDY

-3

/MON

-4

-5

COMA

-2

COMB

-4

/AO

-5

-6

/BO

-8

AO COMA

-2

COMB

-4

/AO

-5

-6

/BO

-8

/TDCON FAND1

FANLK1

GRIPON

+24V

SEPON

Mechanical Controller Board

"H" when print paper is rolled over the transfer drum.

"L" switched to "H" when the transfer drum reaches the registration position. "H" switched to "L" when the transfer drum reaches the TOP position.

"H" when print paper separates from the transfer drum.

"H" to turn ON SL4, operating the gripper drive solenoid.

"H" to turn ON SL4, operating the separation claw.

"L" when there is no toner or cartridge.

/TONLED

"H" to turn ON the LED.

"L" to rotate the main motor at the normal speed, "H" to operate it at half speed.

"L" when main motor rotates normally. "L" to turn ON the main motor.

Toner Carousel Drive Signal

Drum Motor Drive Signal

+24V

"L" to turn ON the cleaning brush motor.

+24VC (0V in the energy-saving mode) "L" when the fan motor rotates normally.

Main Fan Motor

Controller Fan Motor

FM2

FM3

J2019-3

J2010-3

-2

-1

-2

-1

FAND2 FANLK2

FAND3 FANLK3

+24VC (0V in the power-saving mode) "L" when the fan motor rotates normally.

Normally 24V. 16V in the energy-saving mode with the fan motor rotating at half speed.

"L" when the fan motor rotates normally.

95.08.23.11.29

Page 39

Color LaserWriter 12/600 PS Basics & Theory 1–28

Outline of Drive System

The printer has six motors: the pickup motor, main motor, drum motor, toner carousel motor, cleaning brush motor, and scanner motor. See “Motors/Fans/Heaters” in the Parts chapter for additional information.

Pickup Motor (M1)

About the Printer Drive Assembly

The pickup motor is a two-phase stepping motor in the paper pickup block and is controlled by the cassette pickup board. The pickup motor provides mechanical drive to the following parts:

• Cassette pickup roller

• Separation roller

• Registration roller

• Manual feed pickup roller

• Manual feed paper lifting cam

• Feed rollers 1 and 2 The printer drive assembly houses three separate drive trains for main

motor M2, toner carousel motor M3, and drum motor M4. Their delivery points and destinations are as shown:

7 6

Main motor (M2) drive train

Fuser assembly

Paper delivery assembly (via the delivery drive assembly)

Waste toner screw

Transfer drum peripherals

Toner carousel motor (M3) drive train

Toner carousel rotation

Toner cartridge press (via cartridge press drive gear)

Developing cylinder rotation (outer gear)

Drum motor (M4) drive train

Photosensitive drum (coupling at the center of the gear)

Transfer drum

95.08.23.11.29

Page 40

Color LaserWriter 12/600 PS Basics & Theory 1–29

Main Motor (M2)

Toner Carousel Motor (M3)

The main motor is a DC brushless motor. It is controlled by the CPU on the mechanical controller board and provides mechanical drive to the following parts:

• Fuser assembly –Upper and lower fuser rollers –Fuser delivery roller –Oil-applying roller –Oil pump

• Paper delivery assembly

• Transfer drum peripherals –Attraction roller press cam –Transfer drum press cam –Cleaning brush press cam –Discharge roller press cam

• Waste toner screw inside the photoconductor cartridge

The main motor itself is not a part of the printer drive assembly but is available separately as P/N 922-1370.

The toner carousel motor is a two-phase stepping motor controlled by the toner carousel motor driver (Q2003) on the mechanical controller board. This motor is part of the printer drive assembly and provides mechanical drive to the toner carousel.

Drum Motor (M4)

The drum motor is a two-phase stepping motor controlled by the drum motor driver (Q2002) on the mechanical controller board. The drum motor is part of the printer drive assembly. It provides mechanical drive to the photosensitive drum and to the transfer drum.

Drum Motor M4 Toner Carousel

Motor M3

Cleaning Brush Motor (M5)

Position of

Main Motor M2

The cleaning brush motor is a DC motor. It is controlled by the CPU on the mechanical controller board and provides the mechanical drive that rotates the transfer drum cleaning brush.

Scanner Motor The scanner motor is a three-phase, eight-pole DC brushless motor with

a built-in hall element. The scanner motor rotates a six-sided mirror that in turn scans the laser beam, which has been emitted from the laser diode, in the horizontal scanning direction.

95.08.23.11.29

Page 41

Color LaserWriter 12/600 PS Basics & Theory 1–30

Basic Sequence of Operation

Outline The following table describes the ﬁve periods of printer operation. .

Period & Duration Purpose Remarks WAIT (Wait)

From power-on until the fuser roller temperature reaches the target value. This period ﬁnishes in about three minutes at normal room temperature.

STBY (Standby)

From the end of the WAIT period until the /PRINT signal is input from the I/O controller.

From the end of the LSTR period until the /PRNT signal is input from the I/O controller or the power switch is turned off.

INTR (Initial Rotations)

After the /PRNT signal has been input from the I/O controller until the transfer drum rotates up to the top position for the ﬁrst color.

T o warm up the fuser roller to put the printer in the standby state.

To hold the fuser roller at the target value to keep the printer ready to print.

To stabilize the sensitivity of the photosensitive drum in preparation for printing.

During this period, the printer checks for jammed paper and for availability of all the toner cartridges. It also performs image stabilization and other tasks.

If the printer stays in the standby state for 30 minutes or more, it drives the main motor for 0.5 second to rotate the fuser roller, so that the fuser roller will not be deformed.

When the scanner motor reaches the target speed, the DC controller sends the print sequence command to the mechanical controller.

PRINT (Print)

From the end of the INTR period and the subsequent completion of transfer until the transfer drum rotates up to the registration position.

LSTR (Last Rotations)

From the end of the PRINT period until the main motor stops.

To form an image on the photosensitive drum according to the /VDO signal input from the I/O controller and to transfer the image to the paper.

To deliver the last print and to discharge the transfer drum.

Cleaning of the transfer drum occurs after every 100 prints.

95.08.23.11.29

Page 42

Color LaserWriter 12/600 PS Basics & Theory 1–31

III. Laser/Scanner System

Page 43

Color LaserWriter 12/600 PS Basics & Theory 1–32

Laser System

Outline When the /PRNT signal is sent from the I/O controller, the DC

controller performs Automatic Photoemission Control (APC) to stabilize the intensity of the laser beam. Upon completion of APC, the DC controller generates 8-bit video data signals ( with the video signals (

VDO0-VDO7) sent by the I/O controller and then

sends them to the PWM-IC in the laser/scanner assembly . According to the laser drive signal (internal signal in the laser/scanner assembly) output from the PWM-IC, the laser driver circuit turns the laser diode on or off to produce the modulated laser beam.

External Device

I/O Controller Board

/TOP/LSYNC

VDO 0-7

DV2-DV9) in accordance

IMCHR

/PRNT

LLCNT PDIN

M1-M8 Dv2-Dv9 /VDOENB

PWM-IC

Laser Driver

Board

BD Mirror

Collimator Lens

Reflecting Mirror

DC Controller Board

/LSON

Cylindrical Lens

/BDI

/SCNON

Scanner Motor

Scanning Mirror

Focusing Lens

Photosensitive

Drum

BD Board

The modulated laser beam is converted to a parallel beam with the collimator lens and cylindrical lens, and the beam then strikes the scanning mirror, which is rotating at a constant speed.

The laser beam reﬂected by the scanning mirror focuses on the photosensitive drum after passing through the focusing lens and being reﬂected by the reﬂecting mirror. Since the scanning mirror rotates at a constant speed, the laser beam scans at a constant speed across the photosensitive drum which also rotates at a constant speed. As a result, a latent image is formed on the photosensitive drum.

Example: The laser beam comes on in frame 62 for the magenta layer .

The scanner mirror projects it right to left off the reﬂecting mirror, which projects it downward and to the right onto the surface of the

Animation

photosensitive drum.

95.08.23.11.29

Page 44

Color LaserWriter 12/600 PS Basics & Theory 1–33

Video Data Processing

The video data supplied by the I/O controller is composed of 8-bit video signals (

VDO0-VDO7) for each of four colors, M (Magenta), C

(Cyan), Y (Yellow), and K (Black), and the Image Mode Select signal

IMCHR) which is used to set either the text mode (binary mode) or the

( image mode (halftone mode).

Laser Driver BoardDC Controller Board

IC403

PWM-IC

Laser

Drive

Signal

Laser

Driver Circuit

VDO 0-7

IMCHR

IC111

Line

Memory

IC109

Image

Masking

Halftone

Correction

Dv2 to 9

M 1 to 8

Note: In order to ensure that text and halftone images are each properly printed out, the printer switches its image mode via the

IMCHR signal

sent by the I/O controller. In the image data of the printer there is both full-color mode and mono-

chrome mode. In the full-color mode, the I/O controller sends the video signals in the order of M, C, Y, and K to the DC controller. In the monochrome mode, it sends the video signals for only a single color. The video signals (

VDO0-VDO7) and the IMCHR signal sent to the DC

controller by the I/O controller are sent to the gate array (IC109) via IC111 (line memory). IC109 processes

VDO0-VDO7 to perform the

image masking, halftone correction, etc. Note: The printer incorporates the halftone correction table in the DC

controller so that the ideal halftone image can be obtained. This allows the video signals ( corrected and converted to the video data signals (

VDO0-VDO7) sent by the I/O controller to be

DV2-DV9). They are

subsequently output to the laser driver. The signals are then converted to 8-bit video data signals (

and mode setting signals ( board in the laser/scanner assembly. The data signals containing halftone information. The

M1-M8) in IC109 and then sent to the PWM

DV2-DV9 signals are video

M1-M8 signals

DV2-DV9)

control the image mode selection, etc. The PWM circuit modulates the

DV2-DV9 signals into PWM signals and sends them as laser drive

signals to the laser driver board. The printer includes an anti-counterfeiting function whereby a pattern

unique to the printer is invisibly marked on every printout.

95.08.23.11.29

Page 45

Color LaserWriter 12/600 PS Basics & Theory 1–34

Laser Control Circuit

Laser Emission The DC controller generates 8-bit video data signals (

mode setting signals ( with the video signals (

IMCHR) sent by the I/O controller. It sends those signals to the PWM-

(

M1-M8) in the gate array (IC109) in accordance

VDO0-VDO7) and image mode select signal

IC in the laser driver board. Based on the above signals, the PWM-IC produces laser drive signals with the pulse width corresponding to the halftone, and then sends them to the laser driver circuit. At this time, when the forcible laser-on signal ( is “H” and the video-enable signal (

/LSON) sent to the laser driver circuit

/VDOENB) is “L,” the laser driver

board turns the laser diode on in accordance with the laser drive signal.

DC Controller Board

/TOP

/LSYNC

VDO7 to 0

IMCHR

G.A.

(IC109)

Dv2 to 9

M1 to 8

/BDI

Laser Driver Board

Laser Drive Dignal

BD Board

PWM IC

(IC403)

DV2-DV9) and

CPU

(IC101)

Laser Driver Circuit

+5V

APCENB APCLW APCUP PD 12VON

APC-IC

(IC103)

/VDOENB

/LSON

LLCNT

PDIN

+12V

Current/Voltage Conversion Circuit

Switching Circuit

Constant Current Circuit

Note: The APC-IC monitors the voltage levels of the 5 V and 24 V power supplies. If both voltage levels exceed the speciﬁed value, the laser driver board uses 12 V power supply produced from the 24 V power supply.

95.08.23.11.29

Page 46

Color LaserWriter 12/600 PS Basics & Theory 1–35

Laser Intensity Control

The CPU in the DC controller controls the intensity of the laser beam by using the ﬁne control. The APC-IC (IC103) adds the to produce the laser beam intensity control signal (

APCUP signal for rough control and the APCLW signal for

APCUP and APCLW signals

LLCNT), which is

then output to the laser driver circuit in the laser/scanner assembly. The CPU performs automatic power control (APC) of the laser diode and adjusts the

LLCNT signal so that the laser diode will emit the laser beam

at the constant intensity. The APC is composed of initial APC and between-pages APC.

Initial APC The printer performs the initial APC in the following steps while it is

executing the initial rotations. 1 When the APC enable signal

(/APCENB) goes “L,” the CPU

decreases the output values of the laser power control signals

APCLW and APCUP) to zero. After resetting the laser current, the

( CPU rotates the scanner motor.

Note: The

/APCENB signal goes “L” when the 5 V and 24 V power

supplies are at the speciﬁed voltage.

2 The CPU sets the forcible laser-on signal (

video-enable signal ( the D/A output value of the

/VDOENB) to “L” via the gate array . It changes

APCUP signal and gradually increases

/LSON) to “L” and the

the laser diode current. When the laser current increases, the laser diode starts emitting the laser beam. The intensity of the laser beam emitted by the laser diode is detected by the photodiode (PD) and its output voltage is fed back as the laser power detect signal (

PDIN) to

the APC-IC.

3 The CPU monitors the

PDIN signal. Until its value reaches the spec-

iﬁed value stored in the CPU, step 2 is continued.

4 The between-pages APC described below is subsequently

performed during the remaining period of the initial rotations to correct the offset from the target value.

5 The CPU sets the

/LSON signal to “H” to complete the initial APC

and then proceeds to the between-pages APC.

95.08.23.11.29

Page 47

Color LaserWriter 12/600 PS Basics & Theory 1–36

BetweenPages APC

Horizontal Sync Control

Immediately after the initial APC, the printer performs the betweenpages APC for pages and colors. The CPU sets the

/VDOENB signal to

“H” during the unblanking period. Note: In order to detect the

/BDI signal, the laser diode is turned on

even during the period that it does not scan the laser beam across the drum. This is referred to as the “unblanking period.”

This causes the laser diode to emit the laser beam at the intensity set

during the initial APC. To ensure that the value, the

APCLW signal (8-bit) is changed to correct the LLCNT signal

PDIN signal is at the speciﬁed

so as to compensate for the offset from the target value. A small beam-detect (BD) mirror is ﬁxed in the optical path of the laser

beam. Upon reaching the scanning start position, the laser beam is reﬂected by the BD mirror to the BD board in the laser/scanner assembly during the unblanking period. On receiving the laser beam, the BD board generates the beam detect input signal (

/BDI) and then

sends it to the gate array in the DC controller board. The gate array produces the horizontal sync signal (

LSYNC) based on the /BDI signal

and then sends it to the I/O controller.

95.08.23.11.29

Page 48

Color LaserWriter 12/600 PS Basics & Theory 1–37

Laser Diode Emission Control

The laser driver circuit turns the laser diode on or off in accordance with the laser drive signal received from the PWM-IC when the videoenable signal (

/VDOENB) is “L” and the forcible laser-on signal (/LSON)

supplied by the DC controller is “H.” The gate array (IC109) applies left/right and top/bottom margin masking to the video signals (

VDO0) in accordance with the paper size data sent by the I/O controller,

and then sends them as

DV2-DV9 signals to the PWM-IC in the

VDO7-

laser/scanner assembly. The paper size data is supplied to the CPU by the cassette-size sensing switch for cassette paper feed or by the paper size speciﬁcation command issued by the I/O controller for manual paper feed.

Notes: 1 The shaded area permits writing with the laser beam. 2 Times T1 and T2 vary depending on the paper size. 3 If no paper size is speciﬁed by the paper size speciﬁcation command

from the I/O controller for manual feed, the printer does not recognize the paper width. So the T1 and T2 values are assumed to be legal size, the maximum paper width for the printer. The CPU determines the actual paper size from the paper length detected by the paper leading-edge sensor (PS303) when the leading edge of the paper has passed through PS303. Subsequently, the image is masked based on the detected paper size.

/LSYNC

Left/Right Margin

Masking Signal

2 mm

2 mm 2 mm

/TOP

Top/Bottom Margin

Masking Signal

8 mm

95.08.23.11.29

Page 49

Color LaserWriter 12/600 PS Basics & Theory 1–38

Scanner System

Outline The scanning mirror is a critical part in the scanner unit. It is mounted

on the scanner motor shaft and rotates with the scanner motor. The rotation of the scanner motor is controlled by the scanner driver, so that the laser beam reﬂected by the scanning mirror scans across the photosensitive drum at a constant speed. When the scanner motor drive signal

/SCNON) and the scanner clock signal (SCNCLK) are sent to the

( scanner driver by the DC controller, the scanner driver rotates the scanner motor.

Laser/Scanner Assembly

Scanner

Mirror

Motor

Scanner

Unit

/SCNRDY /SCNON /SCNCLK

Controller

Board

95.08.23.11.29

Page 50

Color LaserWriter 12/600 PS Basics & Theory 1–39

Scanner Motor Circuit

The scanner motor is a three-phase, 8-pole DC brushless motor with a hall element. It is incorporated in a single unit with the scanner driver which controls it so that the motor rotates at a constant speed. When the printer is turned on, the oscillation frequency of the crystal oscillator (X103) is divided by the gate array (IC109) and the resulting signal is sent as the

/PRNT signal that is sent to the CPU (IC101) on the DC controller goes

“L,” the CPU sets the

SCNCLK signal to the scanner driver. When the

/SCNON signal to “L” via the gate array and

rotates the scanner motor. When the scanner motor reaches the speciﬁed speed, the scanner motor ready signal (

/SCNRDY) goes “L.” The CPU

on the DC controller issues the print sequence command to the CPU on the mechanical controller when the CPU on the DC controller monitors the

/SCNRDY signal goes “L.” The

/SCNRDY signal via the gate

array to determine whether or not the scanner motor is rotating at the speciﬁed speed. If the scanner motor fails to reach the speciﬁed speed within 30 seconds after it starts rotation, the CPU will stop it and notify the I/O controller of this scanner failure.

/PRNT

J108-29

DC Controller Board

Scanner

Driver

CPU

(IC101)

Gate

Array

(IC109)

148

138

X103

+24V

+5V

SCNCLK

/SCNON

/SCNRDY

J102-10

J102-11

J102-6

J102-8

J102-9

J102-5 J102-7

95.08.23.11.29

Page 51

Color LaserWriter 12/600 PS Basics & Theory 1–40

IV. Image Formation System

Page 52

Color LaserWriter 12/600 PS Basics & Theory 1–41

Outline

The image formation system is the nucleus of the printer. Its major components are the photoconductor cartridge, transfer drum, toner carousel with toner cartridges, and fuser assembly.

Photoconductor Cartridge

Primary Charging Roller

Developing Cylinder

Toner Carousel

Upon receiving the

Photosensitive

Drum

Separation

Discharge

Transfer Drum

Attraction

Roller

Separation

Claw

Discharge Roller

/PRNT signal from the I/O controller, the DC

Fuser

Assembly

Cleaning Brush

controller completes the designated processing and sends the print sequence command to the mechanical controller. The mechanical controller drives various motors and the press cams, which transfer drive throughout the image formation system.

The primary charging roller negatively charges the surface of the photosensitive drum just before the drum surface is irradiated by the laser beam. The latent image formed across the photosensitive drum is made visible by toner from the toner cartridge, and the image is transferred to the paper on the transfer drum. The surface of the photosensitive drum is cleaned to remove residual toner, and the latent imaging cycle continues.

These steps are taken for each color. The paper is fed onto the transfer drum and remains there until the transfer process has been completed. The paper is then separated from the transfer drum and is delivered to the fuser assembly.

95.08.23.11.29

Page 53

Color LaserWriter 12/600 PS Basics & Theory 1–42

The transfer drum is also cleaned periodically to remove toner. However, its surface is discharged to eliminate remaining charges. See “Imaging Stage 4: Transfer Drum Cleaning and Discharge” later in this chapter.

1st Color

2nd Color

Toner Cartridge

Black

Yellow

Magenta

Black

Cyan

Magenta

Cyan

Yellow

Photosensitive Drum

Transfer Drum

Separation Claw

Paper

Cleaning Brush

Discharge Roller

Attraction Roller

3rd Color

4th Color

Magenta

Yellow

Cyan

Black

Magenta

95.08.23.11.29

Page 54

Color LaserWriter 12/600 PS Basics & Theory 1–43

Photoconductor Cartridge

Outline The photoconductor cartridge comprises the primary charging roller,

photosensitive drum, and cleaner unit.

Cleaner

Charging Roller

Primary

Photosensitive Drum

The external surface of the photosensitive drum is a photoconductive layer using an organic photoconductor (OPC), and the inner side is an aluminum substrate. The primary charging roller is formed with rubber of medium resistance, and operates in coordination with the photosensitive drum.

95.08.23.11.29

Page 55

Color LaserWriter 12/600 PS Basics & Theory 1–44

Toner Cartridge

Outline The toner cartridge includes a toner container with stirring plate, a toner

feed roller, rubber blade, and developing cylinder. The developing cylinder, toner feed roller, and stirring plate receive rotational drive through the white toner cartridge drive gear on the photoconductor drive shaft. Toner carousel motor M3 supplies this drive in sync with the drive supplied to the photosensitive drum by drum motor M4.

This internal drive train of the toner cartridge engages with the toner cartridge drive gear only during the “press” position

Note: See “Toner Carousel Control” later in this chapter for full description of “home,” “stop,” “press,” and “fetch” positions.

Toner

Container

Toner Stirring Function

Blade

Developing Cylinder

Stirring Plate

Toner Feed Roller

The toner cartridge stirring mechanism consists of the stirring plate and toner feed roller and helps in supplying toner from the toner container to the developing cylinder. The stirring plate agitates the toner within the container. The feed roller is responsible for applying a thin layer of toner onto the developing cylinder.

95.08.23.11.29

Page 56

Color LaserWriter 12/600 PS Basics & Theory 1–45

CartridgePresence Detection

The printer has cartridge-presence and toner-level detecting functions. Both these functions are served by toner sensor PS11. Cartridge presence is sensed when the cartridge is in the “stop” position.

When a toner cartridge is in the “stop” position, the LED of toner sensor PS11 emits lights through a light pipe in the toner carousel. Each cartridge bay has its own light pipe. The light emitted from the light pipe is normally blocked by the cartridge and does not reach the receiving diode of PS11 mounted above the toner carousel.

Toner Sensor PS11 (Receiver)

Toner Cartridge

Toner Sensor PS11 (Emitter)

If the light does reach the receiving diode, the DC controller determines that no cartridge is installed in that bay and notiﬁes the I/O controller.

Sound: Cartridge-presence sensing occurs after printer startup or

following the actuation of the toner ejection sensor. The controller rotates the carousel to each of the four stop positions, conﬁrms that a

Sound

cartridge occupies each bay , then continues its startup sequences. Click the icon to the left for a sound sampling of the carousel during cartridge-presence sensing.

95.08.23.11.29

Page 57

Color LaserWriter 12/600 PS Basics & Theory 1–46

Toner-Level Detection

When it presses against the photosensitive drum, the cartridge shifts just enough so that the light from PS11 aligns with a window in the bottom of the cartridge. In a totally empty cartridge, the light beam would shoot through this window, out a second window in the top of the cartridge, and strike the receiving diode of PS11.

In a normal cartridge, the controller judges level of toner by measuring the duration that light strikes the receiving diode after the stirring plate has swept in front of the bottom window. If the duration is longer than a prescribed value, the DC controller determines that the toner is low and notiﬁes the I/O controller.

Toner Sensor PS11 (Receiver)

Window

Toner

Animation

Stirring

Plate

Window

Toner Sensor PS11 (Emitter)

Normal Toner-Low

Example: See the cyan cartridge in frame 116 of the animation. This is the position that a cartridge is in when toner level is detected. This position is called the “press” position. It is the only position in which the inner workings of the toner cartridge are mechanically driven. The cartridge is in the “stop” position in frame 115.

95.08.23.11.29

Page 58

Color LaserWriter 12/600 PS Basics & Theory 1–47

Stages of Imaging

The print process is roughly divided into the six stages shown below.

Electrostatic Latent

Image Formation

Delivery

1 Primary Charging

Photosensitive Drum Cleaning

2 Scanner Exposure

4 Drum Cleaning

Fusing

3 Developing

11 Fusing

eveloping

8 Separation

7 Toner Transfer

Transfer Drum

Cleaning/Discharge

9 Cleaning

6 Attraction

10 Discharge

5 Grip

Registration

Manual

Feed

Transfer

Cassette

Feed

Flow of Paper Direction of Photosensitive Drum Rotation

95.08.23.11.29

Page 59

Color LaserWriter 12/600 PS Basics & Theory 1–48

Stage 1: Electrostatic Latent Image Formation

This stage consists of two steps, primary charging and scanning exposure. Upon completion of this stage, the points on the drum that are struck by a laser beam have their charge neutralized, while those points not struck remain negatively charged. The image that is irradiated onto the drum in this manner is invisible and is therefore referred to as a “latent” image.

-100

-500

Surface Electric

Potential (V)

Primary

Charging

(Step 1)

Bright area

Scanning

Exposure

(Step 2)

Dark area

Transfer

(Step 6)

Time (t)

Primary

Charging

(Step 1)

95.08.23.11.29

Page 60

Color LaserWriter 12/600 PS Basics & Theory 1–49

Step 1: Primary Charging

As a preliminary step in forming the latent image, the surface of the photosensitive drum is uniformly charged with negative potential. The primary charging is done by directly imparting charges onto the photosensitive drum.

In order to keep uniform the surface potential charged on the surface of the photosensitive drum, AC bias is superimposed on the primary charging roller in addition to the DC bias.

The AC bias (current value) varies according to the values sensed for temperature and humidity to prevent toner from adhering to the charging roller.

Primary Charging Roller

Photosensitive Drum

Bias

Step 2: Scanning Exposure

When the laser beam is scanned across the photosensitive drum surface, the charge in the irradiated area is neutralized and becomes an electrostatic latent image. This is known as “write-black” laser imaging.

Laser beam

Nonirradiated

Area

Irradiated

Area

95.08.23.11.29

Page 61

Color LaserWriter 12/600 PS Basics & Theory 1–50

Stage 2: Developing

In this stage, the toner is placed on the electrostatic latent image on the photosensitive drum, making the image visible.

Step 3: Developing

The toner used for the printer is a single-component nonmagnetic toner composed of resin. This toner is unique for its insulating property, and is charged with negative potential by friction between the rotating cylinder and blade surface.

The toner comes in four colors: magenta, cyan, yellow and black. Each is contained in its own toner cartridge. Each toner cartridge is housed within the toner carousel and is sequentially advanced to the photosensitive drum in line with the rotation of the carousel. See “Carousel Rotation” later in this chapter.

Blade

Photosensitive

Drum

AC Bias

Developing

Cylinder

Toner Feed RollerStirring Plate

Note: The irradiated areas on the photosensitive drum have a neutral charge. For sake of clarity, these irradiated areas are shown as plus signs (+) since their potential is higher than the charge of toner particles on the developing cylinder.

DC Bias

The laser-beam-irradiated area on the photosensitive drum is higher in potential than the toner negatively charged on the cylinder. When this area comes close to the negatively charged toner on the cylinder, the toner jumps and adheres to the drum surface due to the difference in potential between the drum surface and the cylinder.

This effect is called toner projection development and makes the electrostatic latent image on the photosensitive drum surface visible.

AC bias is applied to the developing cylinder for ease of projecting toner to the photosensitive drum surface and in order to improve the contrast of the output image. DC bias varies in response to density calibration and the operation of the density control panel.

95.08.23.11.29

Page 62

Color LaserWriter 12/600 PS Basics & Theory 1–51

Stage 3: Photosensitive Drum Cleaning

Step 4: Photosensitive Drum Cleaning

During the transfer stage, a small amount of toner does not transfer onto the paper. To prepare for the next imaging cycle, the toner remaining on the photosensitive drum surface is scraped by the cleaner blade and the drum is cleaned.

The scraped toner particles are trapped with the sweeper strip and collected in the toner disposal box by means of the toner transport plate and the waste toner transport screw . The waste toner transport screw is driven by the main motor.

Primary Charging Roller

Laser

Photosensitive

Cleaning Blade

Drum

Toner Transport Plate

Waste Toner Transport Screw

Sweeper Strip

Photosensitive Drum

Waste Toner Transport Screw

Toner Disposal Box

95.08.23.11.29

Page 63

Color LaserWriter 12/600 PS Basics & Theory 1–52

When the photosensitive drum door opens, the shutter lever is released, and the waste toner shutter of the photoconductor closes so that the waste toner is no longer exhausted.

Toner Disposal

Box

Waste

Toner

Outlet

Shutter Lever

Shutter

Lever

Waste

Toner

Outlet

Shutter

Lever

Opening the disposal box cover releases the shutter lever and closes the waste toner outlet.

Closing the disposal box cover presses the shutter lever and opens the waste toner outlet.

Waste

Toner

Outlet

The waste toner level is detected by the waste toner sensor (PS12) housed in the disposal box cover assembly. When the waste disposal box gets full, the DC controller notiﬁes the I/O controller of the waste toner full condition and stops the printer.

PS12 Receiver PS12 Emitter

Waste Disposal Box

Toner

Waste Toner FullNormal

95.08.23.11.29

Page 64

Color LaserWriter 12/600 PS Basics & Theory 1–53

Stage 4: Transfer

This stage consists of four steps: grip, attraction, transfer, and separation. This stage is where the toner image is mapped from the photosensitive drum onto the paper.

Step 5: Grip

When the paper reaches the transfer drum, its leading edge is retained by the gripper so that the paper is retained on the transfer drum surface. Since the leading edge of the paper is retained by the gripper, approximately 8 mm of the leading edge cannot be imaged.

Transfer Drum

Transfer Sheet

Paper

Gripper

Example: The leading edge of the paper is gripped in frame 55 of the animation.

Animation

95.08.23.11.29

Page 65

Color LaserWriter 12/600 PS Basics & Theory 1–54

Step 6: Attraction

The attraction roller imparts negative charges onto the paper and helps hold the paper to the transfer drum surface by means of electrostatic force. The attraction roller presses only for the ﬁrst color and separates from the transfer drum upon completion of the transfer operation for the ﬁrst color.

Note: If you select “Best” as the print quality mode, the entire sheet receives the attraction charge prior to any imaging. This assures the best possible attraction of paper to drum and requires one extra rotation of the transfer drum.

For monochrome and continuous print operation, the attraction roller is separated from the transfer drum upon completion of a single-page transfer, and returns to the drum before the transfer starts for the next page.

Transfer Sheet

Animation

Transfer Drum

DC Bias

Attraction Roller

(Rotates by Friction)

Paper

DC bias

DC bias is applied to the attraction roller. The value of the DC bias varies in line with the temperature/humidity sensing system.

Example: The attraction roller presses in frame 59 of the animation and separates in frame 89 after the trailing edge of the paper passes.

95.08.23.11.29

Page 66

Color LaserWriter 12/600 PS Basics & Theory 1–55

Step 7: Toner Transfer

The paper attracted to the transfer drum is transported in correspondence with the rotation of the transfer drum. At this time, positive charges are applied to the reverse side of the transfer sheet to transfer the toner from the photosensitive drum to the paper. This process repeats sequentially for each color (M, C, Y, K).

Photosensitive Drum

Paper

Toner

Transfer Drum

DC bias

Gripper

Transfer Sheet Elastic Sponge Layer Aluminum Layer

The transfer drum consists of an internal aluminum cylinder covered successively by a conductive elastic sponge layer and an external insulating transfer sheet.

DC bias is applied to the transfer drum. The value of the DC bias varies in line with the temperature/humidity sensing system.

In full-color mode, as the transfer steps proceed with the ﬁrst color, second color, and so on, the transfer force weakens due to the increase in the number of negatively-charged toner particles on the paper. To counteract this effect, the transfer bias is gradually increased for the second and subsequent colors.

95.08.23.11.29

Page 67

Color LaserWriter 12/600 PS Basics & Theory 1–56

Step 8: Separation

Paper is separated from the transfer drum by the gripper and separation claw. After passing through the separation discharge assembly, the leading edge of the paper is pushed up by the gripper and the paper is separated from the transfer drum surface by the separation claw.

AC Bias

DC Bias

Separation

Discharge Assembly

Paper

Transfer Sheet

Transfer Drum

Gripper

Animation

Paper

Separation Claw

Transfer Drum

In a low temperature and low humidity environment, the separation

discharge assembly is activated to assist in separating the paper from the transfer drum.

Note: The separation discharge assembly can be forced on or off manually by means of the density control panel. See “Separation Voltage Designation” earlier in this chapter.

Example: The separation claw actuates in frame 232 of the animation. The paper then separates from the drum and feeds toward the fuser assembly. The leading edge of the paper trips separation sensor PS7 in frame 237.

95.08.23.11.29

Page 68

Color LaserWriter 12/600 PS Basics & Theory 1–57

Stage 5: Transfer Drum Cleaning and Discharge

After the page has left the transfer drum, the printer must return the drum to a clean and electrically neutral state.

Step 9: Transfer Drum Cleaning

During density calibration and after some paper jams, unfused toner may ﬁnd its way onto the surface of the transfer drum. The transfer drum cleaning brush is designed to scrape this residual toner off the transfer drum. This function takes place following density calibration and following the opening/closing of any of the doors. It also occurs as a routine maintenance measure after every 100 prints.

Collected toner is deposited in the ﬁlter of the transfer drum cleaner.

Cleaning Brush

(Motorized Rotation)

Transfer Drum

Cleaning Assembly

Animation

Sound

The cleaning brush is normally separated from the transfer drum. When the transfer process terminates and the paper leaves the transfer drum, the cleaning brush makes contact with the drum, cleans the surface, then separates from the drum.

Note: For more information, see “Transfer Drum Cleaning Assembly” in the “Pickup/Feed System” section of this chapter.

Example: The transfer drum cleaning assembly presses against the transfer drum in frame 223 of the animation, just after the trailing edge of the paper has passed. The assembly separates from the drum in frame 274. As noted above, this press and separation of the cleaning drum assembly occurs in this way only once in 100 prints.

Sound: The transfer drum cleaning assembly has a very distinctive

whining type sound. Click the icon to the left to hear a sampling of this sound.

95.08.23.11.29

Page 69

Color LaserWriter 12/600 PS Basics & Theory 1–58

Step 10: Discharge

AC bias is applied by the discharge roller to eliminate charges remaining on the transfer drum surface after the separation of the paper. The value of the AC bias varies in line with the temperature/humidity sensing system.

Transfer Drum

Discharge Roller

(Rotates by Friction)

AC Bias

Note: For more information, see “Discharge Roller” in the “Pickup/Feed System” section of this chapter.

Animation

Example: The discharge roller presses against the transfer drum in frame 228 of the animation, just after the trailing edge of the paper has passed. The assembly separates from the drum in frame 280.

95.08.23.11.29

Page 70

Color LaserWriter 12/600 PS Basics & Theory 1–59

Stage 6: Fusing

Step 11: Fusing

In the transfer stage, the toner image transferred onto the paper adheres to it only by means of static electricity, and is susceptible to distortion when touched by hand. To avoid this problem, the fuser assembly fuses and mixes the paper and the four toners to create a permanent image.

Note: For more information, see “Transfer Drum Cleaning Assembly” in the “Pickup/Feed System” section of this chapter.

DC Bias

Upper Heater

Upper

Fuser Roller

Toner

Paper

Lower Heater

Lower Fuser Roller

95.08.23.11.29

Page 71

Color LaserWriter 12/600 PS Basics & Theory 1–60

High-Voltage Control: Outline

The high-voltage power supply of the printer is controlled by the high-

voltage control IC (IC1003). In serial communication with the mechanical controller, IC1003 applies voltages to the primary char ging roller, developing cylinder, transfer drum, attraction roller, discharge roller, separation dischar ge assembly, and upper fuser roller in response to the instructions from the mechanical controller.

The primary charging roller , the developing cylinder, and the separation discharge assembly are charged with superimposed DC and AC voltages. The transfer drum is charged with the positive DC voltage. The attraction roller is charged with negative DC voltage being superimposed onto the transfer voltage. The discharge roller is charged with AC voltage being superimposed onto the transfer voltage. The separation discharge assembly normally is charged only with DC voltage and is charged with AC voltage superimposed on DC voltage only in a low temperature and low humidity environment. The upper fuser roller is charged with DC voltage.

Developing

Cylinder

AC Voltage

Generation Circuit

DC Voltage

Generation Circuit

Primary Charging Roller Voltage Circuit

High-Voltage Power Supply Board

Primary Charging Roller

Transfer Drum

AC Bias

Generation Circuit

DC Bias

Generation Circuit

Developing Bias Generation Circuit

High-Voltage Control (IC 1003)

Separation Discharge Assembly

Discharge Roller

Attraction Roller

Attraction Roller Voltage

Generation Circuit

Discharge Roller Voltage

Generation Circuit

Transfer Roller Voltage

Generation Circuit

Upper Fuser Roller

High-Voltage Separation Bd.

AC Voltage

Generation Circuit

DC Voltage

Generation Circuit

Separation Voltage Generation Circuit

Mechanical Controller Board

DC Controller Board

95.08.23.11.29

Page 72

Color LaserWriter 12/600 PS Basics & Theory 1–61

High-Voltage Control: Operation

When the /PRNT signal sent from the I/O controller goes “L,” and the

print sequence command is entered from the DC controller to the mechanical controller, the mechanical controller rotates the drum motor and controls the high-voltage control IC (IC1003) on the high-voltage power supply board as follows.

Voltage to Primary Charging Roller

The high-voltage control IC (IC 1003) on the high-voltage power supply board outputs the primary charging DC voltage drive signal

/HV1DC1), primary charging AC voltage drive signal (/HV1AC1),

( primary charging DC voltage select signal ( AC voltage select signal ( primary charging voltage) ( power supply. The

/HV1DC1 signal and /HV1AC1 signal turn the primary

/HV1AC0), and density adjustment signal (for

/HV1PWM) to control the high-voltage

charging voltage (DC, AC) on or off. The

/HV1DC0), primary charging

/HV1DC0 signal selects the

printing bias or the between-colors bias/between-pages bias.

/HV1AC0 signal switches the primary charging voltage AC current

The value according to the environment detected by the temperature/humidity sensing system. The output value of the

/HV1PWM signal

remains ﬁxed.

/HV1DC0

OFF

Between-Colors Bias/Between-Pages Bias

AC Current : Low

Print Bias

AC Current : High

/HV1DC1

/HV1AC0

/HV1AC1

95.08.23.11.29

Page 73

Color LaserWriter 12/600 PS Basics & Theory 1–62

For the initial rotations, IC1003 sets the

/HV1DC1 signal to “L” and the

/HV1DC0 signal to “L” to apply between-colors bias/between-pages bias

to the primary charging roller. Then, the

/HV1AC1 signal goes “H” so that the primary charging roller is

the

/HV1DC1 signal goes “L” and

charged with the print bias with the primary charging voltage AC bias and DC bias being superimposed. For between-colors/between-pages,

/HV1AC1 signal is set to “H” and only the DC bias is applied, with

the the AC bias turned off.

High-Voltage Power Supply

Primary Charging Roller Voltage Generation Circuit

Constant Voltage Circuit

/HV1PWM

/HV1DC0 /HV1DC1

Integral

Circuit

Voltage

Conversion

Circuit

DC Voltage

Circuit

Generation

Voltage

Detection

Circuit

Overlapping

Primary Charging Roller

HVFre1

HVFre2

Mechanical Controller Board

IC1003 (High-Voltage Control IC)

/HV1AC1

/HV1AC0

Switching

Circuit

Constant Current Controller Circuit

Voltage

ON/OFF

Circuit

Sign Train

Circuit

Generation

Voltage

Selection

Circuit

Amplification

Circuit

Current

Detection

Circuit

HVFre 1, 2 are signals of pulses.

AC Voltage

Generation

Circuit

95.08.23.11.29

Page 74

Color LaserWriter 12/600 PS Basics & Theory 1–63

Developing Bias

When the print sequence starts, the primary charging voltage (AC/DC) is applied and the toner cartridge is pressed against the photosensitive drum to rotate the developing cylinder. Then the high-voltage control IC (IC1003) on the high-voltage power supply board sets the developing bias DC drive signal (

/DEVDC) to “L” and applies the developing

DC bias to the developing cylinder through the developing bias contact behind the mechanical controller board. After the speciﬁed period of time has elapsed, the developing bias AC drive signal (

/DEVAVE) goes

“L” and the voltage superimposing developing AC bias onto developing DC bias is applied to the developing cylinder.

The developing bias is applied only when the toner cartridge is pressed against the photosensitive drum. Before the toner cartridge leaves the drum, the

/DEVDC signal and /DEVAVE signal are set to “H” to turn off

the developing bias. Note: The rotation of the toner press drive gear actuates a rocker pin

that opens and closes the developing bias contact. This completes the circuit to the developing cylinder that is shown on the next page. For more information, see the “T oner Carousel Assembly” topic in the Take Apart chapter.

Developing

Bias Contact

Rocker Pin

95.08.23.11.29

Page 75

Color LaserWriter 12/600 PS Basics & Theory 1–64

As the density adjustment signal (for the developing bias) (/DEVPWM) adjusts image density according to density instructions from the mechanical controller, IC1003 changes the amplitude value of the developing DC bias and the developing AC bias. The

/DEVPWM signal

varies according to image density correction control and the setting of the density control panel.

High-Voltage Power Supply

Developing Bias Generation Circuit

HVFre3

HVFre1

Curve

Forming

Circuit

Switching

Circuit

Constant Voltage Circuit

Generation

AC Bias

Circuit

Overlapping

Voltage

Detection

Circuit

/DEVPWM

/DEVAVE

Mechanical Controller Board

IC1003 (High-Voltage Control IC)

/DEVDC

HVFre1

Integral

Circuit

Integral

Circuit

Voltage

ON/OFF

Circuit

Switching

Circuit

Constant Voltage

Detection

DC Bias

Generation

Circuit

HVFre1, 3 are pulse signals.

Regulator

Developing Cylinder

Voltage

Circuit

95.08.23.11.29

Page 76

Color LaserWriter 12/600 PS Basics & Theory 1–65

Voltage to Transfer Drum

The transfer drum is charged with print bias and between-colors bias according to each print sequence.

For print bias, positive voltage is applied to the transfer drum in order to transfer the toner on the photosensitive drum surface onto the paper.

High-Voltage Power Supply

Attraction Roller Voltage Generation Circuit

/ATRPWM

/HVFre1 /HVATR

/TRPWM

Constant Voltage Circuit

Voltage

Detection

Switch Circuit

Integral Circuit

Circuit

Attraction Roller

Voltage Generation

Constant Voltage Circuit

Circuit

Attraction

Roller

Discharge

Roller

Transfer

Drum

/HVTR

Mechanical Controller Board

HVFre1

IC1003 (High-Voltage Control IC)

/HVSEPAC0 /HVSEPAC1

HVFre4

HVFrel 1, 4 are pulse signals

Switch

Circuit

Transfer Roller Voltage Generation Circuit

Voltage

Conversion

Circuit

Sign Train

Generation

Circuit

Discharge Roller Voltage Generation Circuit

Short Protective Circuits of Transfer Roller Voltage/

Attraction Voltage/Discharge Roller Voltage

Transfer Roller

Voltage Generation

Circuit

Amplification

Circuit

Current

Detection

Circuit

Discharge

Roller

Voltage

Generation

Circuit

Current

Detection

Circuit

Voltage

Detection

Circuit

Current

Detection

Circuit

95.08.23.11.29

Page 77

Color LaserWriter 12/600 PS Basics & Theory 1–66

For full-color transfer, the transfer force weakens as the number of negatively charged toner particles on the paper increases as the transfer step proceeds with the ﬁrst color, second color and so on. To counteract this effect, the transfer bias is gradually increased for the second and subsequent colors. Also, the transfer bias control signal (

/TRPWM) is

changed according to the temperature/humidity sensing system so as to apply an appropriate print bias.

The between-colors bias, with a voltage value smaller than that of the print bias, is applied between colors to minimize the damage to the photosensitive drum.

When the drum motor begins to rotate, the high-voltage control IC (IC1003) on the high-voltage power supply board is charged with the transfer bias by setting the transfer voltage drive signal (

/HVTR) to “L.”

At the same time, the print bias and between-colors bias for each color are applied by varying the

/TRPWM signal.

Voltage to Attraction Roller

Voltage to Discharge Roller

For full-color transfer, the high-voltage control IC (IC1003) on the high-voltage power supply board applies the attraction voltage to the attraction roller by setting the attraction voltage drive signal (

/HVATR)

to “L” before transference of the ﬁrst color image. Also, an appropriate attraction bias is applied by varying the attraction bias value control signal (

/ATRPWM) according to the environment detected by the

temperature/humidity sensing system. After the attraction roller contacts the transfer drum for a speciﬁed period of time, the

/HVATR

signal is set to “H,” and the attraction bias is set to off. When the paper is separated, the high-voltage control IC (IC1003) on

the high-voltage power supply board applies the discharge bias, which is output in response to the combination of the discharge bias (AC) select signals (

/HVSEAC0, /HVSEAC1), to the discharge roller in order to

discharge the transfer drum surface. Based on values sensed by the temperature/humidity sensing system,

the discharge bias changes the combination of the

/HVSEAC1 signals to switch the discharge bias value.

/HVSEAC0

/HVSEAC0 and

/HVSEAC1

OFF Discharge Bias: Low Discharge Bias: Middle Discharge Bias: High

H L H L

H H L L

95.08.23.11.29

Page 78

Color LaserWriter 12/600 PS Basics & Theory 1–67

Voltage to Separation Discharge Assembly

Separation AC voltage is applied to the separation discharge assembly to aid in paper separation when a low temperature and low humidity environment is detected by the temperature/humidity sensing system. Separation DC voltage usually is applied to the upper fuser roller and the separation discharge assembly in print period.

The high-voltage control IC (IC1003) on the high-voltage power supply board sets the separation DC voltage drive signal (

/HVSEP) to

“L” and generates the voltage in the separation DC voltage generation circuit on the high-voltage power supply board. The separation DC voltage is input once to the high-voltage separation board, and applied to the upper fuser roller and the separation discharge assembly. On the other hand, when the separation AC voltage drive signal (

/HVSEPAC)

input from the mechanical controller goes “L,” the separation AC voltage generation circuit in the high-voltage separation board generates the separation AC voltage, and applies it to the separation discharge assembly upon superimposing it onto the separation DC voltage.

Note: The separation discharge assembly can be forced on or off manually by means of the density control panel. See “Separation Voltage Designation” earlier in this chapter.

IC1003

Highvoltage Control

Mechanical Controller Board

/HVSEPAC

/HVSEP

/HVFre1

High-Voltage Power Supply Board

Separation DC Voltage Generation Circuit

Switching

Circuit

High-Voltage Separation Assembly

Separation AC Voltage Generation Circuit

Overcurrent

Protective Circuit

Switching Circuit/ Constant Voltage

Circuit

Circuit DC

Generation

Voltage

AC Voltage Generation

Circuit

Voltage

Detection

Circuit

J1004-6

J1505

J1506

Fuser

Assembly

Separation Discharge Assembly

HVFre 1 is a pulse signal

95.08.23.11.29

Page 79

Color LaserWriter 12/600 PS Basics & Theory 1–68

Photosensitive Drum Life Detection

Outline The printer determines the life of the photosensitive drum mathemati-

cally by tracking page count. When a new photoconductor cartridge is installed, the EEPROM on the DC controller board logs the current page count of the printer. This value becomes the starting page count for that photoconductor. During each subsequent print, the controller compares the running page count against the starting page count stored in EEPROM. If the difference between the two values reaches a prescribed number, the controller determines that end of life has occurred and instructs the I/O controller to report the appropriate alert to the status panel.

Only new cartridges initialize page count. Otherwise, the printer would recognize as new any used cartridge that had been removed and reinstalled. This safeguard is achieved by storing a second value in EEPROM, the thickness of the photosensitive drum.

Note: Before replacing the DC controller board, you must download these values (see Chapter 2). If you are installing a new photoconductor and there is a chance that the old one will be reinstalled, as a troubleshooting measure for example, you must also download these values.

Drum Thickness Detection

The thickness of the photosensitive drum is detected upon power-on, door-open, and each time a certain number of prints is reached. Drum thickness is detected by measuring the discharged current value after charging by the primary charging roller to the photosensitive drum. For correct measurement of the current value, the photosensitive drum and the transfer drum are separated from each other and the thickness detection is performed. See “Drum Separation” below.

The photosensitive drum thickness detection circuit is in the highvoltage power supply board. After the power is turned on and the main motor is turned on, the drum press solenoid (SL7) is turned on and the photosensitive drum and the transfer drum are separated. Then the drum motor is turned on, the primary charging DC voltage drive signal

/HV1DC1) and the primary charging AC voltage drive signal ( /HV1AC1)

( are set to “L,” the primary charging AC voltage select signal (

/HV1AC0)

is set to “L,” and the primary charging DC voltage select signal

/HV1DC0) is set to “H” to apply the primary charging voltage to the

( photosensitive drum.

95.08.23.11.29

Page 80

Color LaserWriter 12/600 PS Basics & Theory 1–69

After charging for a speciﬁed period of time, the /HV1DC1 signal is set to “H,” the application of the primary DC voltage is stopped, and the discharging current value is measured by the photosensitive drum thickness detection circuit on the high-voltage power supply board. The measured current value is sent from the high-voltage control IC to the mechanical controller as the drum thickness sense signals (

SENSE1). The mechanical controller converts these signals into the

and

SENSE0

corresponding time data and sends them to the DC controller. Based on these signals, the CPU on the DC controller determines whether the photoconductor cartridge has been replaced with a new one and whether the photoconductor is installed in the printer.

High-Voltage Power Supply

Photosensitive Drum Thickness Detection Circuit

Primary

Charging

Roller

Photo-

sensitive

Drum

Drum Separation

Current Detection Circuit/

Current/Voltage

Conversion Circuit

Amplification

Circuit

Primary Charging

Roller Voltage

Generation

Circuit

/HV1DC0 /HV1DC1 /HV1AC0 /HV1AC1

Amplification

Circuit

Voltage/Pulse Width

Conversion Circuit

IC1003

High-

Voltage

Control

SENSE0 SENSE1

Filter

Mechanical Controller Board

CPU

The photosensitive drum and the transfer drum are separated when the photosensitive drum thickness detection is performed, the overheadtransparency mode is activated, or the photoconductor cartridge is being replaced. When the mechanical controller sets the drum press signal (

/DDSLON) to “L,” the drum press solenoid (SL7) is turned on

and drum separation cam 1 activates to move the transfer drum away from the photosensitive drum.

95.08.23.11.30

Page 81

Color LaserWriter 12/600 PS Basics & Theory 1–70

Transfer Drum

Roller

Separation Cam 2

Separation Cam 1

Transfer Drum Shaft

When you lower the transfer drum lever, drum separation cam 2 moves the transfer drum away from the photosensitive drum in a manner identical to the solenoid-controlled operation described above.

Transfer Drum

Separation Cam 2

Roller

Transfer Drum Lever

95.08.23.11.30

Page 82

Color LaserWriter 12/600 PS Basics & Theory 1–71

Toner Carousel Control: Outline

The toner carousel consists of four cylindrical bays clustered around a

central press assembly. Each bay is occupied by a single cartridge.

Fetch When you load a cartridge into the printer, that color is said to be in a

“fetch” position. As the cartridge clicks into place, nine separate pins engage. These pins assure a solid coupling that is critical to the mechanical functionality of the printer. See “Toner Cartridge Installation” for more information.

Note: The “home” position of the carousel is the same as the magenta “fetch” position. This is the position of the carousel during standby.

Stop During printing or startup, the carousel rotates counterclockwise to

bring the cartridge to a position facing the photosensitive drum. This is known as the “stop” position. From the fetch to the stop positions, the cartridge housing revolves approximately 135 degrees relative to the inner workings of the cartridge. Therefore, the developing cylinder is fully exposed at the stop position. It has not yet meshed with a drive train. See “Toner Cartridge Stop” in the “Carousel Rotation” section for more information.

Press The cartridge press assembly at the center of the carousel keeps its

position relative to the chassis and does not rotate with the carousel. The moment the cartridge reaches a stop position, the press assembly

shifts it laterally and presses its developing cylinder against the photosensitive drum. This is known as the “press” position and is the only stage in which the inner workings of the cartridge are mechanically driven. Press occurs ﬁrst for magenta, followed in order by cyan, yellow, and black.

See “Toner Cartridge Press” in the “Carousel Rotation” for more information.

95.08.23.11.30

Page 83

Color LaserWriter 12/600 PS Basics & Theory 1–72

Mechanical drive is delivered to the toner carousel in three phases: the rotation of the toner carousel itself, the press and separation of the toner cartridge, and the rotation of the developing cylinder. This sequencing is accomplished by varying the rotational direction of the toner carousel motor and the switching of the toner carousel drive clutch (CL2). The three phases are delivered from three separate points on the printer drive assembly.

Mechanical Controller Board

(/DEVON)

Toner Cartridge Position

Sensor Signal (DEVCAM)

PS3

Toner Carousel

Carousel Rotation

Signal(DEVHP)

Carousel Position Sensor

PS4

Photosensitive

Drum

Carousel Position Detection Flag (1 of 8)

Cartridge Position Detection Flag

Toner Carousel

Developing Rotary

CL1

Motor

Normal

Brake Signal (/DEVBRK)

Developing Rotary Drive Signal

CL2

Developing Motor Drive Signal

Toner Carousel

Clutch (CL2)

On Toner Cartridge Press/Separation Developing Cylinder Rotation

Reverse

Normal

Off

95.08.23.11.30

Page 84

Color LaserWriter 12/600 PS Basics & Theory 1–73

Toner Cartridge Installation

Pins 1, 2, 3

Pins 4, 5, 6

The front face of the toner cartridge has three triangular projections on which positioning pins are mounted. Pins 1 and 3 on the sides mate into the hard plastic of the carousel. Pin 2 on the top mates into a white nylon bushing. These pins help ﬁx the cartridge housing to the carousel in a rotational axis, while still allowing for the slight lateral press that occurs during development. The slot for pin 2 is spring-loaded and also assists in cartridge separation after development.

Pin 2

Slot

Toner Carousel

Slot

Pin 1

Pin 3

Toner Cartridge

There are three toner-color identiﬁcation pins projecting from the carousel end panel. The arrangement of pins is unique for each bay. These pins mate into three slots on the rear face of the cartridge. A fourth slot on each cartridge is plugged to prevent the cartridge from being installed into an incorrect bay.

Magenta

Pins 4, 5, & 6 Slots for Pins 4, 5, & 6

Pin and plug positions are unique for each color. This example shows the cyan bay and cartridge.

Cyan BlackYellow

Plug Position Key

95.08.23.11.30

Page 85

Color LaserWriter 12/600 PS Basics & Theory 1–74

Pins 7, 8

The 3/8" (95 mm) wide pin 7 at the center-point of the cartridge mates into a slot in a spring-loaded bushing in the carousel end panel. This pin functions similarly to pin 2.

Pin 8 is the ﬂex-type pin on the rear face of the cartridge. It mates into a slot in the same bushing as pin 7 described above, but its function is entirely different. A ramped opening into the slot actuates pin 8 and unlocks the toner cartridge so that its inner workings rotate independently of its outer housing. This design accomplishes two things: it keeps toner plumb so as to avoid scattering that would otherwise occur; and it reveals the developing cylinder in synch with a cartridge’s arrival at the “stop” position.

Spring-Loaded Bushing

Pin 7 Pin 8

Slot for

Pin 7

Slot for

Pin 8

Pin 9 The developing bias transfer pin on the carousel end panel presses

against the contact inside the rear face of the cartridge.

Pin 9

Contact for Pin 9

95.08.23.11.30

Page 86

Color LaserWriter 12/600 PS Basics & Theory 1–75

Carousel Rotation The carousel rotates to advance the next toner cartridge to the photo-

sensitive drum.

Internal workings of the toner cartridge rotate independently of the housing. Internal workings remain level throughout carousel rotation.

Photosensitive

Drum

Toner carousel motor M3 delivers rotational drive at this point.

Carousel End Panel

When the print sequence command is received from the DC controller, the mechanical controller sets the developing rotary brake signal

/DEVBRK) to “H,” and the toner carousel brake clutch (CL1) to off to

( release the brake. At the same time, the developing rotary drive signal

/DEVON) is set to “L” and the toner carousel drive clutch (CL2) is

( turned on. Then the toner carousel motor starts driving the rotation of the toner carousel.

The rotational position of the toner carousel is detected by the toner carousel position sensor (PS4) by monitoring the number of passing ﬂags (see “Carousel Rotational Position Detection” below).

95.08.23.11.30

Page 87

Color LaserWriter 12/600 PS Basics & Theory 1–76

Carousel Rotational Position Detection

The rotational position of the toner carousel is detected by the toner carousel position sensor (PS4) by monitoring the number of passing rotational position ﬂags. The eight rotational position ﬂags include the home position ﬂag (which also serves as magenta cartridge fetch position ﬂag) and the fetch and stop position ﬂags for each of three other colors. The home, fetch, and stop ﬂags are of different widths.

When PS4 detects a ﬂag, the developing rotary position sensor signal

DEVHP) is set to “H.” The CPU on the mechanical controller recog-

( nizes which ﬂag (the home position ﬂag, stop position ﬂag, or fetch position ﬂag) is being detected based on the time during which the

DEVHP signal is set to “H.”

Carousel Position Sensor

Yellow Stop

Black Fetch Magenta Fetch

Cyan Stop Black Stop

PS4

and Home Position

Yellow Fetch Cyan Fetch

Magenta Stop

Note: This illustration is diagrammatic and doesn’t show the flags and the sensor in their actual locations. In this example, the yellow cartridge is in the "stop" position opposite the photosensitive drum.

Home

and

Magenta

Fetch

L1=Approx. 11.9 mm L2=Approx. 62.9 mm L3=Approx. 2.2 mm L4=Approx. 64.0 mm L5=Approx. 6.1 mm

Black

Stop

L3L5 L3L5 L3L5

L2 L4 L2 L4 L2 L4

Cyan

Fetch

Magenta

Stop

Width of Flags and Distance Between Flags

Yellow

Fetch

Cyan

Stop

Black Fetch

Yellow

Stop

Home

and

Magenta

Fetch

95.08.23.11.30

Page 88

Color LaserWriter 12/600 PS Basics & Theory 1–77

Toner Cartridge Position Detection

The press/separation of the toner cartridge is detected by the toner cartridge position sensor (PS3) by monitoring the position detection ﬂag. When the cartridge is separated from the drum, the ﬂag interrupts PS3 and the toner cartridge position sensor signal (

/DEVCAM) is set to

“L.” When the cartridge is pressed against the drum, the ﬂag leaves PS3 and

/DEVCAM is set to “H.” The relationship between the cartridge

press cam, press detection ﬂag, and the press sensor is shown below.

Toner Cartridge

Position Sensor (PS3)

Sensor Flag

Stop Position

Photosensitive Drum

Sensor Flag

Press Position

95.08.23.11.30

Page 89

Color LaserWriter 12/600 PS Basics & Theory 1–78

Carousel Rotation Failure

Cartridge Press/ Separation Failure

When the following phenomena are detected by the toner carousel position sensor (PS4), the DC controller is notiﬁed by the mechanical controller and judges them as carousel rotation failures. The DC controller notiﬁes the I/O controller of the faults and stops the printer.

• PS4 does not detect the rotational position ﬂag even though the toner carousel motor rotates.

• PS4 detects an error in the width of the rotational position ﬂag.

• PS4 detects a ﬂag width differing from that of the speciﬁed rotational position ﬂag.

• PS4 does not detect the rotational position ﬂag when the press operation starts.

When the following phenomena are detected by the toner cartridge position sensor (PS3), the DC controller is notiﬁed by the mechanical controller and judges them as toner cartridge press/separation failures. The DC controller notiﬁes the I/O controller of the faults and stops the printer.

• PS3 stays on for a certain period of time after press starts.

• PS3 stays off for a certain period of time after separation starts.

95.08.23.11.30

Page 90

Color LaserWriter 12/600 PS Basics & Theory 1–79

Toner Cartridge Stop

The carousel stops when the next toner cartridge is facing the photosensitive drum.

Photosensitive

Drum

Cartridge Press Drive Gear (Behind Chassis Wall)

Shaft

Cartridge Press Cam (1 of 4)

Cartridge Press Actuator (1 of 2)

When the mechanical controller detects that the carousel has rotated to a stop position, the controller turns off the toner carousel motor. The

/DEVBRK signal is set to “L,” CL1 is turned on to apply a brake, and the /DEVON signal is set to “H” to turn CL2 off.

95.08.23.11.30

Page 91

Color LaserWriter 12/600 PS Basics & Theory 1–80

Toner Cartridge Press

The toner cartridge is pressed against the photosensitive drum.

Photosensitive

Drum

Press Drive Gear Toner carousel motor M3 delivers cartridge press drive through this gear.

Press Cam Actuator

(1 of 2).

After the toner cartridge comes to a stop facing the photosensitive

drum, the mechanical controller reverses the toner carousel motor. The cartridge press cams are driven by the toner carousel motor via the press drive gear. The four cams press the cartridge against the photosensitive drum by means of two actuators. When the cams are about to turn, the controller sets the rotary brake signal (

/DEVBRK) to “H,” and

turns the toner carousel brake clutch (CL1) off to release the brake. Example: The press cams rotate between frames 56 and 57 of the

animation and press the magenta cartridge against the photosensitive drum.

Animation

When the controller detects that the cartridge has begun to leave its bay , the controller measures the amount of the drive to the pressing position, and stops the toner carousel motor according to that timing.

95.08.23.11.30

Page 92

Color LaserWriter 12/600 PS Basics & Theory 1–81

Developing Cylinder Drive

The toner carousel motor rotates the developing cylinder.

Photosensitive

Drum

Stirring

Plate

Developing Cylinder

Toner Feed Roller

Photosensitive drum

receives rotational drive

through the coupling at the center of this gear.

Toner carousel motor M3

delivers developing cylinder

drive at this point.

Developing Cylinder

This mockup does not show toner

carousel and photosensitive drum.

After the toner cartridge is pressed against the photosensitive drum, the mechanical controller rotates the toner carousel motor. The toner carousel motor drives the developing cylinder in the toner cartridge by means of the large white gear on the printer drive assembly into which the photosensitive drum mates.

Note: The photosensitive drum is driven by drum motor M3. Though the drum and carousel motors use separate drive trains, they are delivered in synch by the mechanical controller board.

Upon completion of the developing process for the designated color, the mechanical controller sets the developing rotary brake signal

/DEVBRK) to “L” and the toner carousel brake clutch (CL1) to on to

( apply a brake. The toner carousel motor then stops and the developing cylinder ceases to rotate.

95.08.23.11.30

Page 93

Color LaserWriter 12/600 PS Basics & Theory 1–82

Toner Cartridge Separation

The toner cartridge separates from the photosensitive drum after the development process.

Photosensitive

Drum

GearActuator (1 of 2)

Actuators and Gear During Press

Actuators and Gear After Separation

GearActuator (1 of 2)

After the developing cylinder ceases to rotate, the mechanical controller reverses the toner carousel motor. This motor drives the operation of the cartridge press cam so that the pressure on the press actuator is released and the toner cartridge separates from the photosensitive drum. When the press cam is about to turn, the controller sets the developing rotary brake signal (

/DEVBRK) to “H” and turns the toner

carousel brake clutch (CL1) off. When the toner cartridge position sensor (PS3) detects the cartridge has begun to leave the drum, the controller sets

/DEVBRK to “L” and CL1 to on again, and stops the toner

carousel motor.

95.08.23.11.30

Page 94

Color LaserWriter 12/600 PS Basics & Theory 1–83

Carousel Motor Drive Circuit

The toner carousel motor (M3) is a two-phase stepping motor. The toner carousel motor is controlled by the toner carousel motor driver (Q2003) on the mechanical controller. This motor transmits the driving force to the toner carousel and the toner cartridge press cam.

When the print sequence command is received, the CPU (Q2001) in the mechanical controller sends the toner carousel motor control signals

DEVPHA, /DEVPHA, DEVPHB, /DEVPHB) and the toner carousel motor

( rotation rate select signal (

DEVICH) to the drum motor driver (Q2003)

0.2 second after the main motor starts. Based on those signals, Q2003

supplies the drive signal to the toner carousel motor. 24 VC is supplied for the drive power supply.

When none of the toner cartridges has been installed, exceptional rotational force is required because the carousel’s center of gravity is out of center. Since the mechanical controller cannot recognize whether all cartridges are present or not during operation of the toner cartridge detection function, the CPU reduces the toner carousel rotation rate by setting the

DEVICH signal to “H” to drive the toner carousel motor at

half-speed.

Mechanical Controller Board

CPU

(Q2001)

60 59 58 57

DEVICH

DEVPHA /DEVPHA DEVPHB /DEVPHB

+5V

Toner Carousel Motor Driver

(Q2003)

3 14

6 5 16 17

+24VC

8 1

COMA COMB AO /AO BO /BO

J2016-1

-2

-8

-4

-5

-6

Toner

Carousel

Motor

95.08.23.11.30

Page 95

Color LaserWriter 12/600 PS Basics & Theory 1–84

Image Quality Stability Control

Outline The printer is protected by an image quality control system that mini-

mizes image density ﬂuctuations caused by environmental changes, photosensitive drum wear, and degradation of toner.

Intervals Image quality stability control is performed at the following intervals:

• When the power is turned on

• When the printer encounters an abrupt environmental change

• Following every 100 prints

• When a toner cartridge is installed

• When a new photoconductor cartridge is installed

Environment-change correction control start

Environment detected

Primary charging voltage determined Transfer bias determined Discharge bias determined Attraction bias determined Separation discharge determined

Environment-change correction control end

Maximum density control start

Density detected

Developing bias determined

Temperature/Humidity Sensing

Density Calibration

Maximum density control end

Halftone correction control start

Density detected

Halftone correction table determined

End

95.08.23.11.30

Page 96

Color LaserWriter 12/600 PS Basics & Theory 1–85

Temperature/Humidity Sensing System

The printer has a temperature/humidity sensor board installed under the far end of the toner release assembly.

Temperature/Humidity

Sensor Board

Toner Release

Assembly

The DC controller monitors this sensor and adjusts the following highvoltage values if a change in temperature or humidity is sensed.

• Primary charging

• Transfer bias

• Attraction bias

• Discharge AC bias

• Separation discharge

In addition to the intervals speciﬁed on the previous page, temperature/humidity sensing is performed every 30 minutes while the power is turned on.

Note The separation discharge value can be forced on or off manually by means of the density control panel .

95.08.23.11.30

Page 97

Color LaserWriter 12/600 PS Basics & Theory 1–86

Density Calibration System

Density Control

Halftone Correction Control

Halftone Correction Table

Maximum density control is performed to stabilize the maximum density for each color. This determines an optimum developing bias.

The gate array (IC109) in the DC controller contains the halftone correction table (see below) used to correct the laser output in order to obtain an ideal halftone image. The halftone correction control modiﬁes the halftone correction table to accommodate changes in the present environment, the total number of prints, or the condition of the toner and the photosensitive drum.

The laser output and the image density of the printer do not change in a linear relationship. Therefore, when the laser image is output according to the halftone speciﬁed with the video data signal sent from the I/O controller, an ideal halftone image is not obtained on the actual prints. In order to obtain an ideal halftone image, the DC controller halftone correction table is used to correct the output value of the laser diode.

Image Density

Real Halftone Curve

Ideal Halftone Curve

Laser Output

Density Circuit Maximum density and halftone correction are controlled using the cali-

bration density sensor (PS14).

Calibration Density

Sensor (PS14)

Transfer Drum

Density Sensor Assembly P/N 922-1310

Density Patches

95.08.23.11.30

Page 98

Color LaserWriter 12/600 PS Basics & Theory 1–87

At each of the ﬁve intervals speciﬁed previously, the DC controller

prints a series of patches directly onto the transfer drum. The light emitted by the PS14 LED is reﬂected off these patches and back into the photodiode of PS14.

The reﬂective characteristics of colored toner and black toner differ. Therefore, this sensing circuit uses the density sense mode select signal

/DSEL) to switch between the colored toner density sensing mode and

( the black toner density sensing mode.

When the density sense enable signal ( light with the intensity provided by the LED power control signal (

/DENB) goes “L,” the LED emits

/D0-

7). The photodiode senses the light, which is reflected by the density

sensing pattern on the transfer drum. The density sensing board outputs the density to the DC controller as the toner sensor signal (

DC Controller Board

IC101

CPU

/DENB

/D0 to 7

Density

Sensing

Circuit

/DSEL

DSNS

Density Sensing Board

Calibration Density Sensor

Receiver

DSNS).

(PS14)

Emitter

Note: If the DC controller determines that sensor PS14 is blocked, it will still allow printer operation to continue but will default to factory density settings.

95.08.23.11.30

Page 99

Color LaserWriter 12/600 PS Basics & Theory 1–88

V. Pickup/Feed System

Page 100

Color LaserWriter 12/600 PS Basics & Theory 1–89

Outline

When the

/PRNT signal is sent to the DC controller by the I/O controller

and the scanner motor is put in the ready state, the DC controller issues the print sequence command to the mechanical controller, which then starts printing. After a sheet of paper is picked up by either the cassette or the manual feed pickup rollers, the feed rollers advance it to the registration roller, which corrects any skew. The paper then feeds a short distance to the leading edge detection position, where it pauses to synchronize with the rotation of the transfer drum. The paper then continues through the transfer, separation, and fuser, and is delivered to the face-down or face-up tray.

Separation Claw

Discharge Roller

Registration Roller

Face-down Delivery Roller

Upper Fuser Roller

Face-Up Tray

Lower Fuser Roller

Cleaning Brush

Manual Feed Pickup Roller

Face-Down Tray

hotosensitive Drum

ripper

Transfer Drum

Attraction Roller

Cassette

Leading Edge

Detection Position Cassette Pickup Roller

Manual Feed Tray

Feed Roller

Separation Roller

95.08.23.11.30

Apple 12-600PS, 12 660PS Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Color LaserWriter

Overview

Packaging and Setup Changes

I/O Controller Board Changes

Driver Software

Upgrade Path

Feature added in ROM v2.0

Installation Reimbursement Program

How customers will be informed

Installation procedures

Chapter Contents

Features

Safety Information

Status Panel

Functions

Laser System

Scanner System

Outline

Photoconductor Cartridge

Toner Cartridge

Stages of Imaging

Intervals Image quality stability control is performed at the following intervals:

Outline