1. Before disassembling or assembling parts of the copier and peripherals,
make sure that the copier power cord is unplugged.
2. The wall outlet should be near the copier and easily accessible.
3. Note that some components of the copier and the paper tray unit are
supplied with electrical voltage even if the main power switch is turned off.
4. If any adjustment or operation check has to be made with exterior covers off
or open while the main switch is turned on, keep hands away from electrified
or mechanically driven components.
5. If the Start key is pressed before the copier completes the warm-up period
(the Start key starts blinking red and green alternatively), keep hands away
from the mechanical and the electrical components as the copier starts
making copies as soon as the warm-up period is completed.
6. The inside and the metal parts of the fusing unit become extremely hot while
the copier is operating. Be careful to avoid touching those components with
your bare hands.
HEALTH SAFETY CONDITIONS
1. Never operate the copier without the ozone filters installed.
2. Always replace the ozone filters with the specified ones at the specified
intervals.
3. Toner and developer are non-toxic, but if you get either of them in your eyes
by accident, it may cause temporary eye discomfort. Try to remove with eye
drops or flush with water as first aid. If unsuccessful, get medical attention.
OBSERVANCE OF ELECTRICAL SAFETY STANDARDS
1. The copier and its peripherals must be installed and maintained by a
customer service representative who has completed the training course on
those models.
2. The NVRAM on the system control board has a lithium battery which can
explode if replaced incorrectly. Replace the NVRAM only with an identical
one. The manufacturer recommends replacing the entire NVRAM. Do not
recharge or burn this battery. Used NVRAM must be handled in accordance
with local regulations.
1
1.
SAFETY AND ECOLOGICAL NOTES FOR DISPOSAL
Do not incinerate toner bottles or used toner. Toner dust may ignite
suddenly when exposed to an open flame.
2. Dispose of used toner, developer, and organic photoconductors in
accordance with local regulations. (These are non-toxic supplies.)
3. Dispose of replaced parts in accordance with local regulations.
4. When keeping used lithium batteries in order to dispos e of them later, do not
put more than 100 batteries per sealed box. Storing larger numbers or not
sealing them apart may lead to chemical reactions and heat build-up.
LASER SAFETY
The Center for Devices and Radiological Health (CDRH) prohibits the repair of
laser-based optical units in the field. The optical housing unit can only be repaired
in a factory or at a location with the requisite equipment. The laser subsystem is
replaceable in the field by a qualified Customer Engineer. The laser chassis is not
repairable in the field. Customer engineers are therefore directed to return all
chassis and laser subsystems to the factory or service depot when replacement of
the optical subsystem is required.
ø
WARNING
Use of controls, or adjustment, or performance of procedures other than
those specified in this manual may result in hazardous radiation exposure.
ø
WARNING
Turn off the main switch before attempting any of the procedures in the
Laser Unit section. Laser beams can seriously damage your eyes.
CAUTION MARKING:
2
TABLE OF CONTENTS
1. OVERALL MACH INE INFORMATION........................................1-1
A3 SIZE FULL COLOR MODE......................................................................4
2. SP MODE TABLE
3. SC CODE TABLE
XIV
24 February, 1999SPECIFICATIONS
0
9
1. OVERALL MACHINE INFORMATION
1.1 SPECIFICATIONS
1.1.1 MACHINE CONFIGURATION
A258A259A260
Operation Panel
Paper Tray Unit
Edit Function
Sorter/Stapler
A555
40-digit 4-line LCD
Hard Key Type
500 sheetsDuplex
NoNoYes
Platen Cover
A749-00
Overall
Information
144 mm x 192 mm (10.4 inch)
Color Touch Panel Display
ARDF
A663
A834
A849
Copier
Paper Tray Unit (500 sheets per tray)
A833
A832
FPU A846
FPU Table
A7
2-1
I/F A848
A259V501.WMF
1-1
SPECIFICATIONS24 February, 1999
1.1.2 GENERAL SPECIFICATIONS
Configuration:Desktop
Copy Process:Dry electrostatic transfer system
Resolution:400 dpi; Printer mode 600 dpi
Gradations:256 gradations
Originals:Sheet/Book/Object
Original Size:Maximum 11" x 17" /A3
Copy Paper Size:
MaximumMinimum
Paper Tray Feed
(A258 only)
Bypass Feed
Copy Paper Weight:
Paper Tray Feed
Bypass Feed
Auto Duplex Tray
11" x 17" /A35
12" x 18"/305 mm x 457 mmA6(L)
17 to 28 lbs.64 to 105 g/m
14 to 43 lbs.52 to 160 g/m
17 to 28 lbs.64 to 105 g/m
2
2
2
1/2
x 8
/A5(L)
1/2
Reproduction Ratios:
8
" x 11"LT/11" x 17"DLT
1/2
A4/A3 version
version
Enlargement
Full size
Reduction
Programmable
Full Color (4 scans) 6 cpm 3 cpm
Single Color (C, M Y, K)A258: 21 cpm
A259/260: 28 cpm
A258: 11 cpm
A259/260: 14 cpm
Single Color (B, G) 9 cpm4.5 cpm
Single Color (R) 7 cpm3.5 cpm
OHP/Thick Paper Mode
Full Color (4 scans) 3 cpm1.5 cpm
Single Color (C, M Y, K) 5 cpm2.5 cpm
Single Color (G, B) 4 cpm 2 cpm
Single Color (R)3.5 cpm1.5 cpm
Duplexing: Same as Normal Mode speed in the above table
Printer Speed: 2/3 the speeds shown in the above table
First Copy Time (A258/259/260):
Overall
Information
8
" x 11" (S) /A4
1/2
Normal Mode
Full Color (4 scans)22.4 seconds
Single Color (K) 8 seconds
Single Color (C, M, Y)10 seconds
Single Color (B, G, R)16 seconds
OHP/Thick Paper Mode
Full Color (4 scans)35 seconds
Single Color (K)23 seconds
Single Color (C, M, Y)25 seconds
Single Color (B, G, R)27 seconds
Warm-up Time: Approx. 7 minutes (at 68°F / 20°C)
1-3
SPECIFICATIONS24 February, 1999
Duplexing:
Basic Manual Duplex
Model (A258):
Basic Auto Duplex
Model (A259):
Edit Auto Duplex Model
(A260):
Manual duplexing in full color and single
color modes
Manual & auto duplexing in full color and
single color modes
Manual & auto duplexing in full color and
single color modes
Duplexing can be done on 64-105 g/m2 paper.
Manual duplexing can be done through the
bypass table only, and the user should press
the Duplex Side 2 key before copying the reverse
side.
Non-Reproduction Area:
Leading Edge:
Side:
0.2" ± 0.08" (5 mm ± 2 mm)
0.08" ± 0.08" (2 mm ± 2 mm)/
Total less than 0.16" (4 mm)
Trailing Edge:
2.0 mm + 2.0/-1.5 mm
Copy Number Input:Number keys, 1 to 99
Copy Number Input
(Auto Duplex):
Number keys
Single Color - 1 to 50: smaller than A3, 11" x 17"
1 to 30: A3, 11" x17"
Full Color1 to 20: all sizes
Image Density:Auto/Manual (9 steps)
Automatic Reset:Yes (10 to 990 seconds or Off)
Paper Capacity:Tray:
500 sheets x 1 tray
(Basic Manual Duplex Model: A258)
Bypass:
Normal paper (80 g/m2/20 lb) 50 sheets
OHP 20 sheets
Adhesive paper 1 sheet
Toner Replenishment:Toner Addition (K, Y, C, M) (220 g/cartridge)
Copy Tray Capacity:100 sheets (11" x 17"/A3 and smaller)
Power Source:US: 120V/12A/60Hz,
Sorter Stapler: A555 (10 bins), A834 (20 bins),
Sorter: A849 (3 bins)
Film Projector: A846
Holder for Film Projector Unit: A702-19
Paper Tray Unit: A832 (2 trays), A833 (3 trays)
Key Counter
Platen Cover: A749-00
Original Tray: A430-07 (Type F)
Overall
Information
1-5
SPECIFICATIONS24 February, 1999
1.1.3 PLATEN/ARDF ORIGINAL SIZE DETECTION
Size (width x length)
[mm]
A3 (297 x 420) LNoYesNoYes
B4 (257 x 364) LNoYesNoYes
A4 (210 x 297) LNoYesYesYes
A4 (297 x 210) SNoYesYesYes
B5 (182 x 257) LNoYesNoYes
B5 (257 x 182) SNoYesNoYes
A5 (148 x 210) LNoNo*NoYes
A5 (210 x 148) SNoNoNoYes
B6 (128 x 182) LNoNoNoYes
B6 (182 x 128) SNoNoNoYes
11" x 17" (DLT)YesNoYesYes
11" x 15"NoNoYesNo
10" x 14"NoNoYesYes
8.5" x 14" (LG)YesNoYesNo
8.5" x 13" (F4)NoNoYesYes
8.25" x 13"NoNoNoNo
8" x 13"(F)NoYesYesNo
8.5" x 11" (LT)YesNoYesYes
11" x 8.5" (LT)YesNoYesYes
8" x 10.5"NoNoNoNo
8" x 10"NoNoYesNo
5.5" x 8.5" (HLT)No*NoYesNo
8.5" x 5.5" (HLT)NoNoYesNo
A6 (105 x 148) LNoNoNoNo
InchesMetricInchesMetric
PlatenARDF
*: For A5 lengthwise/HLT, SP4-303 can be used to select “Cannot detect
original size” or “A5 lengthwise/5.5" x 8.5"(HLT)”.
1-6
24 February, 1999SPECIFICATIONS
1.1.4 COPY PAPER SIZE
Optional
S.Stapler
Size
(width x length)
[mm]
Trays in the main bodyBypass
Paper Tray (A258)
Duplex Tray
(A259/A260)
InchesMetricInchesMetric
All
versions
(A258/
259/260)
A3 (297 x 420) LNoYesYesYesYesYes
B4 (257 x 364) LNoYesYesYesYesYes
A4 (210 x 297) LYesYesYesYesYesYes
A4 (297 x 210) SYesYesYesYesYesYes
B5 (182 x 257) LNoYesNoYesYesYes
B5 (257 x 182) SNoYesNoYesYesYes
A5 (148 x 210) LNoYesNoNoYesYes (1)
A5 (210 x 148) SNoNoYesYesYesYes (2)
B6 (128 x 182) LNoNoNoNoYesYes (1)
B6 (182 x 128) SNoNoNoNoNoNo
12” x 18”NoNoNoNoYesYes (3)
11" x 17" (DLT)YesYesYesYesYesYes
11" x 15"YesNoYesNoYesYes
10" x 14"YesNoYesNoYesYes
8.5" x 14" (LG)YesNoYesNoYesYes
8.5" x 13" (F4)YesYesYesYesYesYes
8.25" x 13"NoNoYesYesYesYes
8" x 13"(F)NoNoYesYesYesYes
8.5" x 11" (LT)YesYesYesYesYesYes
11" x 8.5" (LT)YesYesYesYesYesYes
8" x 10.5"NoNoYesNoYesYes
8" x 10"YesNoYesYesYesYes
5.5" x 8.5" (HLT)NoNoNoNoYesYes (1)
8.5" x 5.5" (HLT)YesNoYesYesYesYes ( 2)
A6 (105 x 148) LNoNoNoNoYesYes (2)
Overall
Information
Yes (1): Stapling is not allowed.
Yes (2): Using the proof tray only. Sorter bins cannot be used.
Yes (3): 20-bin sorter (A834): Stapling is not allowed.
1) The tables indicate the copy paper size for each original for 50 to 200 %
zoom ratios.
2) After specifying a zoom ratio, APS automatically selects a paper size
that guarantees the quality of the magnified copy image, if there is a
paper size available for the equivalent standard reproduction ratio.
3) If there is no paper that corresponds to the detected size, the machine
displays the message "Set xx paper in tray" and stops the job (copying
is still possible).
4) For "—" in the above tables, the machine displays the message "Cannot
detect original size" and stops the job (copying is still po ssible). The
selected paper feed tray does not change.
5) When less than 49% or more than 201% is selected, APS behaves in
accordance with note 4 above.
6) APS also supports the by-pass feed table (except for non-standard
paper sizes). When the paper size selected by APS can only be fed
from the by-pass feed table, the machine displays a warning to instruct
the user to use the by-pass feed table.
7) APS does not support A6, B6, and A5.
Overall
Information
1.1.6 NOISE EMISSION
Sound pressure level
The measurements were made in accordance with ISO 7779 at the operator
positions.
Copier onlyFull system*
Less than 38.5 dB (A)Less than 55 dB (A)
*: Full system: Copier with document feeder, 500 sheets x 3 trays unit, FPU,
and a sorter stapler.
Sound power level
The measurements were made in accordance with ISO 7779.
Copier onlyFull system*
Stand-byLess than 55 dB (A)Less than 59 dB (A)
Copying
(This value is for the
black copy mode.)
*: Full system: Copier with document feeder, 500 sheets x 3 trays unit, FPU,
and a sorter stapler.
Less than 68 dB (A)Less than 72 dB (A)
1-9
SPECIFICATIONS24 February, 1999
1.1.7 POWER CONSUMPTION
(1) Maximum power cons umption
1.5 kVA
(2) Average power consumption
A258/A259/A260 Copiers
Standby
Warm-up
Copying
Energy Saver Mode
0.4 kW
1.3 kW
1.1 kW (B/W A4 å)
0.6 kW (full color A4 å)
Value for standby minus 25 W
1.1.8 DISPLAY EDITOR SPECIFICATIONS
Scanned image
Displayed image
Area specification
procedure
•
The copier's scanner scans the image.
•
Maximum A3/DLT (11" x 17"): Redu ced image display
•
144 x 192 mm, 256 colors (8 bits/dot)
•
640 x 480 dots, 0.33 mm/dot
Reduces the dpi of scanned images to approximately 25
dpi and displays the entire image
•
Zoom display: 4 levels (200%, 264%, 400%, 528%)
•
Move the arrow on the screen by using the cursor key
and enter a point by pressing the coordinate entry key.
1-10
24 February, 1999MECHANISM OVERVIEW
1.2 MECHANISM OVERVIEW
1.2.1 IMAGE GENERATION PROCESS
Overall
Information
10
11
9
12
1
2
3
4
5
8
A259V110.WMF
67
1-11
MECHANISM OVERVIEW24 February, 1999
(1) Drum charge
The charge corona applies a negative charge to the OPC drum and the grid
ensures that this charge is even.
(2) Quenching
After cleaning, the OPC is fully exposed to light from an array of red LEDs,
quenching the residual charge on the OPC drum in preparation for the next copy
cycle.
(3) Drum Cleaning
The cleaning brush increases drum cleaning efficiency by applying lubricant to the
OPC drum. The cleaning blade scrapes the residual toner off the OPC drum.
(4) PCC (Pre-cleaning corona)
The PCC discharges the photoconductor drum and applies AC and negative DC to
reduce the charge holding the residual toner to the drum, thereby improving the
efficacy of the cleaning brush.
(5) Belt transfer
Positive charge applied to the back of the transfer belt transfers the toner image on
the OPC drum to the transfer belt.
(6) Paper transfer
The negatively charged toner image is transferred to the paper by giving a positive
charge to the back of the paper while the paper and transfer belt are held in close
contact.
(7) Paper separation corona
After transfer, the separation corona quenches the negative charge on the paper to
reduce the attraction between the belt and paper. The curvature of the belt causes
the paper to separate from the transfer belt.
(8) Belt cleaning unit and lubricant application brush
The brush applies lubricant, which makes it easier for the counter blade to scrape
excess toner off the transfer belt.
1-12
24 February, 1999MECHANISM OVERVIEW
(9) ID sensor
The ID sensor detects the density of the sensor patches developed on the OPC
drum. The signal from the ID sensor is used for process control and toner supply
control.
(10) Development
The latent image on the drum attracts the negatively charged toner. Toner is
preferentially attracted to those places on the drum surface where the laser
reduced the negative charge. The development units for each color are included in
the revolver unit.
(11) Potential sensor
The potential sensor detects the electrical potential (the strength of the electric
field) on the photoconductor dru m for process contr ol.
(12) Laser exposure
The polygon mirror reflects the laser beam emitted from the laser diode and
projects it onto the drum through the f-theta lens, drum mirror, and toner shield
glass. The laser output varies in intensity to correspond to the image data, and this
forms a latent image on the drum.
Overall
Information
1-13
MAJOR UNIT LAYOUT AND PAPER FEED PATH24 February, 1999
1.3 MAJOR UNIT LAYOUT AND PAPER FEED PATH
1
2
3
8
7
4
6
1-14
5
A259V109.WMF
24 February, 1999MAJOR UNIT LAYOUT AND PAPER FEED PATH
(1) Scanner
1. 400 dpi, 10-bit scanning in both main and sub-scan directions
2. 3-line CCD
3. Halogen exposure lamp
4. 5-phase stepper motor drive
5. Dual-side continuous scan (A4) support (in continuous copy mode)
(2) Operation panel (A259, A260)
1. 10.4-inch (640 x 480) color LCD (8-bit) touch-panel
2. An additional operation panel is installed when the printer controller is installed.
2. Polygon mirror motor (16535 rpm) with ball bearing
3. 400 dpi (8 bits per pixel for each color) in copy mode
600 dpi (8 bits per pixel for each color) in printer mode
4. Modulation: PM + PWM
Overall
Information
(4) Transfer belt
1. Transfer belt: Always in contact with the drum
2. Belt transfer: Indirect application of voltage with a roller
3. Paper transfer: Roller transfer
4. Registration: Synchronization by the transfer belt H.P. sensor
5. Drive: Synchronized with the drum (same motor)
6. Separation: Curvature separation + corona unit
7. Transfer cycle: 1 belt rotation/A4, 2 rotations/A3
8. Belt cleaning: Counter blade
9. Lubrication: Brush roller with lubricant bar
1-15
MAJOR UNIT LAYOUT AND PAPER FEED PATH24 February, 1999
(5) Paper feed/transport system
1. Paper feed (A258)
•
Front loading 500 sheets, 1-layer tray + by-pass feed
2. Transport: Transport belt + fan
3. Duplexing: Duplex unit installed as a standard component (A259/A260 only)
4. Paper tray (optional): Holds 500 sheets x 2 trays or 500 sheets x 3 trays.
(6) Fusing and paper exit
1. Fusing: Silicone roller fusing
2. Oil application method: Do uble roller system
3. Cleaning: Cleaning rollers (for hot and pressure rollers)
Europe/Asia:
Cleaning roller for hot roller, cleaning blade for pressure roller
4. OHP/thick paper speed change
(7) Development and toner supply
1. Development: Two-component magnetic brush development
2. Development switching: Revolver system
3. Image density control: ID sensor + process control
4. Toner supply: Screw-in bottle (220 g)
5. Toner supply unit: Front of developer unit (rotation type)
(8) Drum unit
1. The drum unit contains the photoconductor drum, charge corona unit, and
cleaning unit.
2. Charge corona unit: Single-wire scorotron
3. Quenching lamp: LED array
4. Drive: Synchronized with the transfer belt (DC brushless motor + flywheel)
5. Potential sensor included
1-16
24 February, 1999PARTS LAYOUT
1.4 PARTS LAYOUT
1.4.1 MECHANICAL COMPONENT LAYOUT
567891113 14
1210
Overall
Information
4
3
2
1
1. Paper Tray (A258)/Duplex Tray
(A259/A260)
2. Pressure Roller
3. Hot Roller
4. 2nd Scanner
5. Revolver Development Unit
6. 1st Scanner
7. Drum Mirror
8. Toner Shield Glass
9. BTL (Barrel Torroidal Lens)
10. Charge Corona Unit
11. Scanner Lens
12. 2nd F-theta Lens
15
16
17
18
19
20
21
A259V108.WMF
22232425
14. 1st F-theta Lens
15. Polygon Mirror
16. Drum Cleaning Unit
17. OPC Drum
18. Transfer Belt
19. By-pass Feed Table
20. Transfer Belt Unit
21. Registration Roller
22. Transfer Belt Bias Roller
23. Paper Transfer Unit
24. Belt Cleaning Unit
25. Transport Belt
13. CCD Board
1-17
PARTS LAYOUT24 February, 1999
1.4.2 ELECTRICAL COMPONENT LAYOUT
20
19
18
17
16
21
15
22
1
2
3
4
5
6
7
23
8
9
10
11
12
13
A259V101.WMF
14
1. Scanner Motor Drive Board
2. Scanner Motor
3. Platen Cover Position Sensor
4. IDU Board
5. Original Length Sensor
6. Lamp Regulator
7. Scanner Exhaust Fan
8. CCD Board (SBU)
9. Scanner IPU Board
10. Main Control Board
11. LD (Laser Diode) Main Control
Board
Diagram 1
12. Laser Synchronizing Detector
Board 2
13. Polygon Motor Drive Board
14. Polygon Motor
15. LD (Laser Diode) Drive Board
16. Laser Synchronizing Detector
Board 1
17. Optics Anti-condensation Heater
18. Original Width Sensor
19. Exposure Lamp
20. Optics Cooling Fan
21. Scanner H.P. Sensor
22. Thermostat
23. Original Length Sensor-Sub
1-18
24 February, 1999PARTS LAYOUT
14
13
12
2
1
3
Overall
Information
4
5
6
7
11
A259V102.WMF
10
9
8
Diagram 2
1. Main Power Switch
2. Belt Cleaning H.P. Sensor
3. Paper Tray Detector Switch
4. Transfer Belt Home Position Sensor
5. Transfer Belt Heater
6. Paper Height Sensor-1
7. Paper Height Sensor-2
8. Paper Transfer H.P. Sensor
9. Paper Transfer Unit Heater
10. Counters
11. Transport Fan
12. Front Door Switch
13. Paper Exit Door Switch
(A259/A260 only)
14. Junction Gate Solenoid
(A259/A260 only)
1-19
PARTS LAYOUT24 February, 1999
1
2
3
4
16
15
14
13
12
1. Paper Transfer Positioning Clutch
2. Paper Feed Motor
3. Registration Clutch
5
6
7
8
9
10
A259V103.WMF
11
Diagram 3
9. By-pass Pick-up Solenoid
10. Upper Limit Sensor
11. Paper End Sensor
4. Relay Clutch
5. By-pass Feed Clutch
6. Paper Feed Clutch
7. By-pass Paper Width Detection
Board
8. Vertical Transport Switch
12. Relay Sensor
13. By-pass Paper End Sensor
14. By-pass Feed Table Switch
15. Registration Sensor
16. Temperature and Humidity Sensor
1-20
24 February, 1999PARTS LAYOUT
10
9
1
8
7
6
Overall
Information
5
4
3
19
18
17
16
15
1. Operation Panel
2. Paper Separation Corona Unit
2
11
12
13
A259V104.WMF
14
Diagram 4
10. Pressure Roller Thermistor
11. Duplex Entrance Sensor
3. Pressure Roller Thermofuse
4. Pressure Roller Fusing Lamp
5. Paper Exit Sensor
6. Oil End Sensor
7. Hot Roller Thermistor
8. Hot Roller Fusing Lamp
9. Hot Roller Thermofuse
12. Duplex Turn Sensor
13. Duplex Paper End Sensor
14. Duplex Feed Motor
15. Side Fence Jogger HP Sensor
16. Duplex Side Fence Jogger Motor
17. Duplex End Fence Jogger Motor
18. Duplex Control Board
19. End Fence Jogger HP Sensor
1-21
PARTS LAYOUT24 February, 1999
1
10
2
9
8
7
6
5
1. Charge Corona Unit
2. Quenching Lamp
3. PCC (Pre-cleaning Corona)
4. ID Sensor
5. Charge Corona Fan
3
A259V105.WMF
4
Diagram 5
6. Toner Cartridge Sensor
7. Revolver H.P. Sensor
8. Toner End Sensor
9. High Voltage Supply Board: B
10. Potential Sensor
1-22
24 February, 1999PARTS LAYOUT
2
1
3
Overall
Information
4
5
6
9
A259V106.WMF
1. Development Clutch
2. Toner Supply Motor
3. Revolver Motor
4. Belt Lubricant Clutch
5. Fusing Motor
8
7
Diagram 6
6. Fusing Clutch
7. Belt Cleaning Clutch
8. Tray Lift Motor
9. Drum Motor
1-23
PARTS LAYOUT24 February, 1999
1
2
12
11
10
9
8
7
Diagram 7
1. High Voltage Supply Board: C, G
2. Rear Cooling Fan
3. Fusing Unit Fan
4. PSU (Power Supply Unit)
5. High Voltage Supply Board: T2, D
6. CSS/Bank Interface Board
3
4
A259V107.WMF
56
7. Revolver Motor Drive Board
8. Used Toner Sensor
9. High Voltage Supply Board: T1,
PCC
10. Main Exhaust Fan
11. I/O (Input/Output) Control Board
12. PSU Fan
1-24
24 February, 1999PARTS LAYOUT
1.4.3 DRIVE LAYOUT
5
1
Overall
Information
2
3
4
A259V111.WMF
Five motors drive the mechanical components for this machine. The drive sections
driven by these five motors are listed below.
1. Scanner Drive
2. Development/Drum/Transfer Belt
Drive
3. Paper Feed/Registration/Paper
Transfer/Transport Belt Drive
4. Fusing Unit/Paper Exit Drive
5. Revolver Drive
1-25
PARTS LAYOUT24 February, 1999
1.4.4 AIR FLOW
1
2
3
4
8
5
A259V112.WMF
1. Optics Cooling Fan
2. Fusing Unit Fan
3. Rear Cooling Fan
4. Scanner Exhaust Fan
5. Main Exhaust Fan
6. Transport Fan
7. Charge Corona Fan
8. PSU Fan
67
1-26
24 February, 1999PARTS LAYOUT
1.4.5 ELECTRICAL COMPONENT DESCRIPTIONS
Printed Circuit Boards
SymbolNameFunctionIndex-NoLocation
PCB 2
PCB 5
PCB3
PCB1PSUSupplies AC and DC power.7-4K4
PCB4
PCB11 Main control boardControls the printer sequence.1-10J12
PCB6
PCB17
PCB16 LD drive boardDrives the las er diode.1-15O17
PCB12
PCB13
PCB21 IDUAnalyzes images for anti-counterfeiting.1-4M14
PCB18
PCB9
PC8
PCB10
PCB7
PCB19 Operation panel board Used to operate the copier.4-1H19
PCB22
PCB14
PCB15
PCB20
PCB23
Lamp regulatorSupplies AC power to the exposure
lamp.
Scanner motor drive
board
SBUConverts the light reflected from the
Scanner IPU board
I/O control boardInterfaces the sensors, clutches,
LD main control board Controls the laser power, main scan
Laser synchronizing
detector board 1
Laser synchronizing
detector board 2
By-pass paper width
detection board
High voltage supply
board: T2, D
High voltage supply
board: T1, PCC
High voltage supply
board: B
High voltage supply
board: C, G
Polygon mirror motor
drive board
Revolver motor drive
board
Interface board:
CSS/Bank
Duplex control boardControls the duplex unit.
Temperature and
humidity sensor board
Supplies DC power to the scanner
motor.
original into video signals.
Converts the RGB image signal from the
CCD to a KCMY signal and sends it to
the LD main control board.
solenoids, and motors in the printer
module with the main control board.
synchronizing sensors, and process
control gamma correction.
Detects laser main scan synchronization
while the latent image is being written to
the drum.
Detects laser main scan synchronization
while the latent image is being written to
the drum.
Detects the paper width on the by-pass
feed table.
Supplies power to the paper transfer
bias roller and paper separation corona
unit.
Supplies power to the transfer belt and
pre-cleaning corona unit.
Supplies power to the development
rollers.
Supplies power to the charge corona
wire and grid.
Controls the polygon mirror motor.
Controls the revolver motor.
Connects to the CSS unit and optional
paper tray unit.
Detects the ambient temperature and
humidity.
1-6O7
1-1M7
1-8J9
1-9L8
7-11D14
1-11M16
1-16O15
1-12O15
3-7A10
7-5A1
7-9A2
5-9A3
7-1A14
1-13O15
7-7F5
7-6J9
F20
4-18
3-16E19
(A259/A260
copiers only)
Overall
Information
1-27
PARTS LAYOUT24 February, 1999
Motors
SymbolNameFunctionIndex-NoRemarks
M1Scanner motorDrives the scanner.1-2M6
M2Polygon mirror motorDrives the polygon mirror (laser unit).1-14O15
M11Fusing motorDrives the transport and fusing units.6-5E8
M7Paper feed motorDrives the paper feed unit.3-2A12
Tray lift motorLifts the tray bottom plate.
M8
Drum motor
M10
M9Toner supply motorSupplies toner.6-2A7
M3Revolver drive motorRotates the revolver unit.6-3G5
Duplex Side fence
M5
M6
M4
jogger motor
Duplex End fence
jogger motor
Duplex feed motorDrives the paper feed roller in the
Drives the drum, the development unit
currently at the development position,
and the transfer belt.
Drives the duplex unit side fences.
Drives the duplex unit end fences.
duplex unit.
6-8
6-9A19
4-16
4-17
4-14
A12
(A258
models only)
G21
(A259/A260
copiers only)
G21
(A259/A260
copiers only)
G20
(A259/A260
copiers only)
Fan Motors
SymbolNameFunctionIndex-NoRemarks
FM4Scanner exhaust fanCools the scanner unit.1-7P7
FM2Optics cooling fanCools the scanner unit1-20O14
FM3Charge corona fanCools the charge corona unit.5-5A6
FM6
FM1Transport fanAttracts copy paper to the transport belt.2-11A11
FM5Fusing unit fanCools the fusing unit.7-3E1
FM7Rear cooling unit fanCools the rear section of the copier.7-2E10
FM8PSU fanCools the PSU.7-12A7
Main exhaust fan
Sucks air from the charge and transfer
areas out of the machine.
7-10A17
1-28
24 February, 1999PARTS LAYOUT
Sensors
SymbolNameFunctionIndex-NoRemarks
S21
Platen cover position
sensor
S23Scanner H.P. sensorDetects the scanner home position.1-21P14
S20Original length sensor Detects the length of the original.1-5N7
S24Original width sensorDetects the width of the original.1-18P14
S16
Transfer belt H.P.
sensor
S18Paper exit sensorDetects paper jams at the paper exit.4-5F1
S2
Toner cartridge sensor Detects the presence or absence of
S1Toner end sensorDetects the presence or absence of
S4
Potential sensorDetects the potential of the drum
ID sensorDetects the density of toner on the
S5
S3
S17
Revolver H.P. sensorDetects if the revolver is at the home
Registration H.P.
sensor
Relay sensor
S9
S12Used toner sensorDetects if the used toner tank is full7-8A15
S6
S13
S7
Belt cleani ng H.P.
sensor
Paper transfer H.P.
sensor
By-pass feed paper
end sensor
Upper limit sensorDetects the upper limit position of the
S8
Paper height sensor 2 Detects the amount of paper in the
S15
Paper height sensor 1
S14
Tray paper end sensor
S10
Side fence jogger HP
S25
sensor
End fence jogger HP
S26
sensor
Duplex paper end
S27
sensor
Detects if the platen cover is opened or
closed.
Detects the mark on the transfer belt.
toner cartridges.
toner in a cartridge.
surface.
developed ID sensor patch on the
drum.
position.
Detects paper jams at the registration
section.
Detects paper jams at the relay
section.
Detects if the belt cleaning unit is at the
home position.
Detects if the paper transfer unit is at
the home position.
Detects if there is paper on the by-pass
feed table.
tray bottom plate.
tray.
Detects the amount of paper in the
tray.
Detects if there is paper in the paper
feed tray.
Detects the home position of the
duplex unit side fence.
Detects the home position of the
duplex unit end fence.
Detects if there is paper in the duplex
unit.
1-3O7
2-4A18
5-6A4
5-8A4
5-10A5
5-4A5
5-7A4
3-15A19
A13
3-12
(A258
models only)
2-2A8
2-8A15
3-13A8
A13
3-10
(A258
models only)
A16
2-7
(A258
models only)
A16
2-6
(A258
models only)
G13
3-11
(A258
models only)
G22
4-15
(A259/A260
models only)
G22
4-19
(A259/A260
models only)
G22
4-13
(A259/A260
models only)
Overall
Information
1-29
PARTS LAYOUT24 February, 1999
SymbolNameFunctionIndex-NoRemarks
S28
S29
S19
S22
S11
Duplex entrance
sensor
Duplex turn sensorDetects when copy paper is being
Oil end sensorDetects if there is silicone oil in that
Original length sensor -
sub
Relay SensorDetects a paper jam at the relay
Detects when copy pa per comes into
the duplex unit.
reversed in the duplex unit.
tank.
Detects the length of the original
section
G23
4-11
(A259/A260
models only)
G23
4-12
(A259/A260
models only)
4-6G1
1-23P7
A14
3-12
(A259/A260
models only)
Switches
SymbolsNameFunctionIndex-NoRemarks
SW1Main power switchTurns the power to the copier on or off.2-1M1
Front door switchCuts the DC line to the high voltage
SW2
SW3
SW4
SW5
SW6
Paper exit door switch Detects if the paper exit door is open or
By-pass feed table
switch
Paper tray detector
switch
Vertical transport
switch
supply board when the front door is
open.
closed.
Detects if the by-pass feed table is open
or closed.
Detects the presence or absence of a
paper tray.
Detects if the vertical transport door is
open or closed.
2-12E11
A7
2-13
(A259/A260
models only)
3-14A8
A16
2-3
(A258
models only)
3-8A17
Clutches
SymbolsNameFunctionIndex-NoRemarks
CL1
CL3
By-pass feed clutch
Registration clutchTransmits drive to the registration
CL6Relay clutchTransmits drive to the relay rollers.3-4A18
CL2
Paper feed clutch
CL8Fusing clutchTransmits drive to the fusing unit.6-6E1
CL9
Belt lubricant clutchTransmits drive to the belt lubricant
CL7Belt cleaning clutchTransmits drive to the belt cleaning unit.6-7E2
CL5
CL4
Development clutchTransmits drive to the development
Paper transfer
positioning clutch
Transmits drive to the by-pass feed
mechanism.
rollers.
Transmits drive to the paper feed
mechanism.
mechanism.
mechanism.
Transmits drive to the paper transfer
unit.
1-30
3-5A9
3-3A18
3-6A17
6-4E2
6-1E3
3-1A11
24 February, 1999PARTS LAYOUT
Solenoids
SymbolsNameFunctionIndex-NoRemarks
SOL1
SOL2
By-pass pickup
solenoid
Junction gate solenoid Raises the junction gate for the duplex
Lowers the by-pass pick-up roller.
tray.
3-9A9
2-14
(A259/A260
copiers only)
A7
Lamps
SymbolNameFunctionIndex-NoRemarks
L1Hot roller fusing lampProvides heat to the hot roller.4-7H1
Pressure roller fusing
L2
lamp
Exposure lampApplies high intensity light to the original
L3
Quenching lamp
L4
Provides heat to the pressure roller.
for exposure.
Neutralizes any charge remaining on the
photoconductor.
4-4G1
1-19O5
5-2A6
Overall
Information
Heaters
SymbolNameFunctionIndex-NoRemarks
H3
H1
H2
Optics anticondensation heater
Paper transfer unit
heater
Transfer belt heater
Prevents moisture from forming on the
optics.
Prevents moisture from forming around
the paper transfer unit.
Used to stabilize the temperature
around the transfer belt.
1-17L1
2-9J1
2-5K1
Thermistors
SymbolNameFunctionIndex-NoRemarks
TH2
TH1
Hot roller thermistorControls the temperature of the hot
roller.
Pressure roller
thermistor
Controls the temperature of the
pressure roller.
4-6G1
4-9F1
Thermofuses
SymbolNameFunctionIndex-NoRemarks
TF1Hot roller thermofuseProtects the hot roller from overheating.4-8H1
TF2
Pressure roller
thermofuse
Protects the pressure roller from
overheating.
4-3H1
Thermostat
SymbolNameFunctionIndex-NoRemarks
TS1
ThermostatPrevents the exposure lam p from
overheating when it is on for a long time.
1-31
1-22O6
PARTS LAYOUT24 February, 1999
Counter
SymbolNameFunctionIndex-NoRemarks
CO1
CO2
Upper mechanical
counter
Lower mechanical
counter
Indicates the total number of
development cycles made using the C,
M, and Y development units;
Shows the total number of black
developments.
2-10A9
2-10A10
1-32
24 February, 1999PROCESS CONTROL
2. DETAILED DESCRIPTIONS
2.1 PROCESS CONTROL
2.1.1 OVERVIEW
This copier provides the following forms of process control:
•
Potential control (done every process control self check)
•
Process control gamma calibration (done every process control self check,
after potential control)
•
Toner supply control (done every copy)
The components used for process control are:
•
Potential sensor (a new type of sensor is used, known as a ‘feedback
measurement potential sensor’). This sensor detects the surface potential of
the drum.
•
ID sensor (a new type of sensor is used, known as a ‘diffused reflection ID
sensor‘). The ID sensor detects the amount of toner on the drum.
Detailed
Descriptions
Revolver
LD
V
B
Drum
ID sensor
Potential
sensor
Pixel
counting
V
G
Fuzzy logic
Toner supply
calculation
Motor rotation time
Process
control
γ
Development
characteristics
Development
potential calculation
Pointer table
V
D
LD main
ASIC
VBV
L
Toner supply motor
2-1
VGVBI
A259A001.WMF
LD
PROCESS CONTROL24 February, 1999
2.1.2 POTENTIAL CONTROL
Overview
Potential control is the process of controlling the development potential to maintain
the density of the toner image on the drum. It does this by compensating for
variations in drum chargeability and toner chargeability.
The machine uses the image density (ID) sensor to measure drum reflectivity and
the density of a standard sensor pattern. It uses the potential sensor to detect the
potential on the standard sensor pattern (before the pattern is developed). These
tests are done during the process control self check, which is done at specific times
(such as after replacing the developer).
The ID and potential sensor outputs are used to calculate the development
potential. This is the difference between the development bias voltage and the
voltage of areas of the drum that have been discharged by laser exposure at full
power. If changes in this potential are not accounted for, the color balance will be
poor.
Depending on the development potential that is calculated, the machine uses a
look-up table in memory (called a pointer table) to adjust the following:
•
VD: Drum potential without exposure - to adjust this, the machine adjusts the
charge corona grid voltage (V
•
: Drum potential with the strongest exposure - to adjust this, the machine
V
L
G)
adjusts the laser diode input current (ILD)
•
VB: Development bias
Potential control controls the development potential so that the maximum amount
of toner applied to the drum is kept constant. However, the medium (greyscale)
range is ignored. To improve this situation, a new process called ‘process control
gamma correction’ is done after potenti al contr ol. Thi s pr ocess de fin es LD output
for all 256 grades of the greyscale (development bias and charge corona grid
potential are not affected).
Potential Control Timing
The machine carries out potential control and process control gamma correction
during the ‘process control self check’. There are five types of process control self
check, categorized according to their execution times. Process control takes
approximately 3 minutes.
(1) Forced process control
After replacing the drum, the technician must do the forced process control
procedure (SP3-126). There is no need to use SP3-126 at installation, because
forced process control is included in the developer initialization process (SP2-225).
(See 6.6.3 Developer Collection Procedure for details.)
2-2
24 February, 1999PROCESS CONTROL
(2) Initial process control self check
The initial process control starts automatically when the power is turned on (or
when the machine returns to standby mode from sleep mode), but only if the hot
roller in the fusing unit is less than 100 degrees centigrade. This process control is
done only when SP3-125 (Set Potential Control Method) is set to "0 (Auto)."
(3) Interval process control self check
The interval process control starts automatically at the end of a copy job during
which the total number of copies exceeds a preset value.
The preset value can be defined using SP3-973 (Set Process Control Self Check
Interval). The factory setting is 150 sheets. The maximum possible interval is 500
sheets. Using a shorter interval reduces the machine’s average copying speed.
Setting the process control interval to 0 disables the interval process control.
(4) Timed process control self check
The timer is reset to 6 hours after a process control self check, at the end of a copy
job, when the power is switched on, after toner end recovery, or if the front door is
opened and closed.
The 6-hour interval can be adjusted with SP 3-972.
(5) ACC-Run-Time Process Control Self Check
A process control self check that is active before the execution of ACC (auto color
calibration). The checks is identical to the interval process control self check.
Detailed
Descriptions
2-3
PROCESS CONTROL24 February, 1999
2.1.3 PROCESS CONTROL SELF CHECK
Flow Chart
Start
VSG Adjustment (ID sensor)
ID sensor pattern generation
Sensor pattern potential
detection
Sensor pattern density
detection
Toner amount calculation
Development potential
calculation
VD, VB, VL selection
Process control gamma
correction
Step (1)
Step (2)
Step (3)
Step (4)
Step (5)
Step (6)
Step (7)
End
A259A002.WMF
2-4
24 February, 1999PROCESS CONTROL
Step 1: VSG Adjustment
The type of ID sensor used in this machine responds differently for black and color,
so there are two V
The type of ID sensor used in this machine is very sensitive, and outputs some
voltage even if there is no light being reflected off the drum. This output is known
as the ‘offset’. It is about 1 V for black and about 0.2 V for color, but is different for
each sensor. For more details on this sensor (known as a ‘diffused reflection ID
sensor’), see ‘Step 4: Sensor Pattern Density Detection’.
The ID sensor checks the bare drum’s reflectivity and the machine calibrates the
output of the ID sensor as follows. This voltage is known as VSG:
•
Black: (1.8 + offset) ± 0.1V
•
Color: Must be between 0.2 and 3 V
This calibration compensates for the drum’s condition (due to ageing) and the ID
sensor condition, such as dirt on the surface of the drum or ID sensor.
Note that VSG for black is less than half that in previous models. This is due to the
new type of ID sensor.
values, one for black toner and one for CMY toner.
SG
Detailed
Descriptions
Step 2: ID Sensor Pattern Generation
The machine makes a 16-grade pattern on the drum for
each toner color. Each grade is made by changing the
LD power. At this stage, the patterns are not developed;
they remain as latent images.
1st level
of LD power
2nd level
of LD power
3rd level
of LD power
15th level
of LD power
16th level
of LD power
20
25
20
A259A004.WMF
2-5
PROCESS CONTROL24 February, 1999
Step 3: Sensor Pattern Potential Detection
Process
The potential sensor detects the potential on each grade of the 16-grade sensor
pattern latent image, for each colour, and the output is stored in memory.
Feedback Type Potential Sensor
d
[B]
[A]
V
Feedback circuit
dc
A259A003.WMF
This copier uses a feedback potential sensor. A description of the principles of
feedback potential sensors follows.
The detector [A] detects the strength of electric fields emitted from the drum
surface, which depend on the surface potential of the drum. The feedback circuit
applies voltage to the probe [B] until the electric field strength is offset at the
detector. The level of this voltage determines the magnitude of the surface
potential on the drum surface and is presented as output.
The major features of this measurement method are:
•
Even if the distance [d] between the drum (1) and the potential sensor (2)
fluctuates, the measurement of the drum surface potential is still accurate.
•
The potential sensor does not have to be calibrated before the process control
self check, so the calibration step required for previous models can be skipped.
•
Residual potential affected the calibration for the older type of sensor, so before
process control self checks, the machine had to wait 10 minutes in standby
mode for the residual voltage to disappear. For this new sensor, calibration is
not needed, so the influence of residual potential on the drum can be ignored.
2-6
24 February, 1999PROCESS CONTROL
Step 4: Sensor Pattern Density Detection
Process
The development rollers of the respective colors develop the sensor pattern latent
images for K, Y, C, and M generated in Step (2). In Step (4), the ID sensor detects
the densities of the 16 patch patterns for each color. This data goes to memory.
Diffused Reflection ID Sensor
Drum
LED
Detector
A259A006.WMF
(Direct Reflection
Type ID Sensor)
Toner
Diffuse
Beam
Detector (Diffused
Reflection Type ID
Sensor)
A259A007.WMF
LED
Drum
Toner
Other Diffuse
Beams
This copier uses a diffused reflection ID sensor. In addition to the ray directly
reflected from the drum, there are diffuse beams reflected at all angles from the
toner on the drum. This sensor detects image density by receiving some of these
diffuse beams, not by receiving the beam directly reflected from the toner.
Using this type of sensor improves the measurement accuracy of the sensor
pattern densities particularly for Y, C, and M toners. The following explains why.
Detailed
Descriptions
Color (Y, C, M) toners
SP
V
min
V
(1): Component of light reflected from the drum
(2): Component of light reflected from C, M, or Y toner
Figure A
Relationship between the output of the normal reflection type ID sensor
A259A008.WMF
and the amount of toner on the drum for C, M, and Y toners
SP = (1) + (2)
V
(2)
(1)
M/A
2-7
PROCESS CONTROL24 February, 1999
Figure B
output of the diffused reflection ID
sensor and the amount of toner on the
drum for C, M, and Y toners
Relationship between the
A259A009.WMF
Figure C
output of the diffused reflection ID sensor
and the amount of toner on the drum for
K toner
Relationship between the
A259A010.WMF
Figure A shows the relationship between the output of the normal reflection ID
sensor and the amount of Y, C, or M toner attached to the drum. This shows that
the ID sensor output (Vsp) results from not only the light reflected from the toner
but also the component of light reflected from the drum.
With this old sensor type, the machine was unable to accurately detect high values
of M/A for colored toner (i.e., to the right of the minimum in the VSP curve at Vmin.
The diffused reflection ID sensor, on the other hand, picks up little light that is
reflected from the drum. So, the relationship between the diffused reflection ID
sensor output and the amount of toner on the drum is linear, as shown in Figure B.
This means that high densities of colored toner can be measured accurately.
K toner
The ID sensor output for K toner tends to decrease as the density of toner on the
drum increases. Therefore, the relationship between the ID sensor output and the
amount of K toner on the drum is as shown in Figure C.
Step 5: Toner Amount Calculation
The amount of toner on the drum (M/A, mass per unit area, mg/cm2) is calculated
for each of the 16 grades of the sensor pattern from the ID sensor output value
(Vsp) from each grade of the pattern.
2-8
24 February, 1999PROCESS CONTROL
Step 6: Development Potential Calculation
V
When the development
potential is smaller
Amount of toner
on the drum
V
D
V
B
V
L
A259A011.WMF
V
X
V
D
V
B
V
L
When the development
potential is larger
X
The development potential (VDP) is the capability to attract toner to the drum and
can be shown as: VB - V
•
: Development bias
V
B
•
VL: Drum potential after full laser exposure
L
See the above drawing for two examples.
The machine calculates the approximate current development potential from the
sensor readings. This consists of the following steps:
1. The machine converts the gradation pattern densities (from the ID sensor) into
an actual toner amount on the drum (M/A) for each grade of the pattern.
Detailed
Descriptions
2. From the potential and ID sensor outputs, the machine then determines the
relationship between the drum potential and the amount of toner developed on
the drum. This is known as the development gamma factor, or γMA.
3. The machine can now calculate the development potential (VDP) that would be
required to obtain the ideal toner density (known as M/A max) on an area of the
drum developed with full laser power, under the machine’s present conditions.
MAmax
MA
γ
Amount of
toner
Vdp
Vk
Vkp
MAmax = 0.7
mg/cm2 for each
color
Development potential
A259A012.WMF
2-9
PROCESS CONTROL24 February, 1999
NOTE:
For Y, C, and M toners, the new type of ID sensor allows higher densities
of toner to be measured accurately (refer to the descriptions in Step 4,
Sensor Pattern Density Detection). This permits the calculation of γ M/A at
a higher accuracy than a normal reflection ID sensor, because the
measurements at higher densities (M/A values) are more reliable.
Step 7: Selecting the Optimum VD, VB, V
L
The machine now adjusts VD, VB, and VL to try to bring the development potential
VDP to the ideal value. To do this, it uses a pointer table. This is a look-up table in
ROM of VDP against VD, VB, and V
L.
The machine takes the value of VDP calculated in the previous section, and looks
for the value of VDP in the pointer table that is closest to this. The machine reads
the values of VD, VB, and VL that are in this row of the pointer table.
The machine will then use these values of VD, VB, and VL during copying until the
next process control self check. These values are designed to bring the actual V
DP
to the optimum value for the machine’s current condition.
•
VD: Drum potential without exposure - to adjust this, the machine adjusts the
charge corona grid voltage (VG)
•
VL: Drum potential with the strongest exposure - to adjust this, the machine
adjusts the laser diode input current (ILD)
VB: Development bias
2-10
24 February, 1999PROCESS CONTROL
2.1.4 PROCESS CONTROL
What is process control
γγγγ
?
γγγγ
CORRECTION
After process control, the proper values for VD, VB, VL have been defined for the
maximum laser power. However, the medium (greyscale) range is ignored. To
improve this situation, a new process called ‘process control gamma correction’ is
done after potential control. This process defines a suitable LD output for all 256
grades of the greyscale.
Process control gamma correction takes about 30 seconds.
How is it done?
ID sensor
output
Target
B
C
Actual
Actual LD
value
VSP range
D
Detailed
Descriptions
D
A
Input LD value
A
Target LD value
A259D556.WMF
Based on the maximum laser power just defined during the process control self
check, the machine writes another 16-grade sensor pattern on the drum.
NOTE:
This is different from the sensor pattern made during potential control –
that pattern always uses 16 fixed laser power levels.
The ID sensor detects the density developed on these patterns and compares
them with the target densities in ROM. The target densities and the actual densities
can be plotted as shown in the diagram above left.
NOTE:
To make the curve of actual densities, the machine draws a curve through
the density points read from the 16-grade pattern made for process control
gamma.
From this, the machine determines how much to correct the LD power when
attempting to write a certain density on the drum.
In the example in the diagram, for a laser power of A, the machine expected an ID
of B. However, the actual result was C. To get an ID of B, the machine has to use a
laser power of D. The expected ID can be plotted against the actual ID as shown in
the diagram above right; this is the process control gamma curve.
Process control γ target values are stored in the NV-RAM on the main control
board. The CPU calculates the process control γ on this board. The results of the
process control γ calculation go to the LD main control board to compensate the LD
input data.
The process control gamma obtained cannot be adjusted in SP mode.
2-11
PROCESS CONTROL24 February, 1999
Process control gamma correction timing
The machine automatically does process control gamma correction at the end of
every process control self check.
2-12
24 February, 1999TONER SUPPLY CONTROL
2.2 TONER SUPPLY CONTROL
2.2.1 TONER SUPPLY CONTROL METHOD
This machine has two toner supply control meth ods: fuzzy control mode, and fixed
supply mode.
Normally this machine uses fuzzy control. The fixed supply method is used only
when abnormal conditions occur during the process control self check.
2.2.2 FUZZY CONTROL MODE
Copy
Vsp Detection for Toner
Supply Control
Fuzzy Control
Required Amount of Toner
is Determined
Toner Supply Motor
Duration is Calculated
Detailed
Descriptions
Image Area Ratio
A259D668.WMF
First, the machine assesses the amount of toner per unit ar ea on the dru m (M/A) .
This is determined from two sensor inputs: Vsg, and Vsp(toner).
The fuzzy logic algorithm then uses the most recent M/A values to assess current
toner density conditions.
The output from the fuzzy logic process is then combined with the image area ratio
obtained from the image data signal coming from the IPU board. The result of this
calculation is the amount of toner required, and from this, the machine determines
the time that the toner supply motor must stay on in order to supply the correct
amount of toner.
2-13
TONER SUPPLY CONTROL24 February, 1999
2.2.3 VSP DETECTION FOR TONER SUPPLY CONTROL
The copier generates an ID sensor pattern using a
20 mm
standard laser diode power. The copier generates this
pattern between the K, C, M, and Y images, and then
detects the density using the ID sensor. The result is
20 mm
known as ‘VSP for toner supply control’, or ‘VSP (toner)’
to distinguish it from the ot her VSP, measured during
potential control.
This process is done after
•
Each color development cycle for odd-numbered copies when making
A259A015.WMF
continuous copies of A4/LT landscape size or smaller.
•
Each color development cycle, every copy in all other modes.
2.2.4 CALCULATING THE AMOUNT OF TONER ON THE DRUM
A259D552.WMF
Y, M, C toner
A259A009.WMF
K toner
First, the machine calculates a value from the current VSP (toner) value. Then, it
refers to a table in the ROM to determine the toner density on the drum (M/A).
•
M/A: Toner amount per unit area on the drum (mg/cm2)
The target M/A for toner supply control is 0.4 mg/cm2 for the C, M, and Y toners
and 0.3 mg/cm2 for the K toner. M/A is calculated in the same way as for potential
control.
Fuzzy Logic Algorithm
The fuzzy logic algorithm has two input factors which are related to the amount of
toner on the drum. These are:
•
The difference between the average of the previous 10 M/As and the target M/A
•
The tendency of the previous 10 M/As
2-14
24 February, 1999TONER SUPPLY CONTROL
Image Area Ratio
This is a measure of how much toner will be needed for each color on a page.
From the image data from the image processing unit (IPU), the machine
determines the total amount of the color on the page. It takes into account the
grayscale values for each pixel for that color.
2.2.5 FIXED SUPPLY MODE
In fixed supply mode, the machine adds a fixed amount of toner to the developer
every copy. Readings from the ID sensor are ignored.
SP 2-208-005 to 008 define the toner supply ratios for each color in fixed supply
mode.
2.2.6 TONER SUPPLY IN ABNORMAL SENSOR CONDITIONS
The machine detects that the ID sensor is abnormal if the detected VSG value is
out of the required range three consecutive times during process control. After that
SC 385 is displayed and logged. Switching the main switch off/on recovers the
machine and the toner supply method falls back to fixed supply mode.
If the abnormal condition is recovered during the next process control, the machine
automatically selects the fuzzy control mode again.
Detailed
Descriptions
2-15
TONER SUPPLY CONTROL24 February, 1999
2.2.7 DETECTING TONER NEAR END/END
0.40.6
YMC TonerK Toner
A259D554.WMF
0.25
A259D555.WMF
Toner Near-end
For the Y, C, and M toners, the copier first detects toner near-end using the toner
end sensor (see ’Development – Toner End Detection’). The toner end sensor
detects the toner end condition during development. Then, VSP is checked. If both
toner end sensor and VSP indicate near-end, the machine indicates a near-end
condition for that color.
For K toner, the copier detects the toner near end condition using the ID sensor
only. Light cannot pass through K toner as well as C, M, or Y. So toner adhering to
the window inside the toner hopper blocks the light returning to the sensor.
Therefore the copier cannot accurately detect how much K toner remains using the
toner end sensor.
Toner End
After a toner near-end condition is generated, the copier uses the write mode pixel
counter and sheet counter to detect toner end. This is done in the same way for all
colors (K, C, M, and Y).
2-16
24 February, 1999TONER SUPPLY CONTROL
Toner near end detection
Toner end sensor
The toner end sensor detects light reflected from a mirror inside the toner hopper
(see ‘Development – Toner End Detection’). There are two levels of output, namely
High (5V: no reflection/toner present) and Low (0V: reflection detected/no toner).
For C, M, and Y toners, the toner near end detection routine using VSP begins
when the toner end sensor detects four consecutive low signals.
This sensor does not work for K toner because toner adhering to the window
blocks reflection back to the sensor. For K toner, only VSP is used.
Detailed
Descriptions
Toner near end detection routine using V
SP
Toner near end is displayed on the operation panel when the amount of toner
(M/A) calculated during toner supply control is less than the target supply (0.4
mg/cm2 for C, M, and Y; 0.25 mg/cm2 for K) five times in succession.
Toner end detection
When a color reaches the toner near-end condition, 10 more pages can be made
with that color.
Then, if during those 10 pages, the pixel count for the color in question reached
500%, the copier displays toner end for that color and that color cannot be used.
(100% is defined as one A4 image with the color in question covering the whole
page at full strength.)
If the pixel count has not yet reached 500% after 10 pages, copying can continue
until the pixel count reaches 500%. Then, the copier displays toner end for that
color and that color cannot be used.
If the pixel count reaches 500% during the first 10 pages, copying is not stopped,
but that color toner may appear pale on the output.
This process is the same for the K, C, M, and Y toners.
2-17
TONER SUPPLY CONTROL24 February, 1999
Toner end recovery
The copier enters the recovery process in the following cases:
1. The front door is opened and a toner cartridge is removed or inserted.
This is regarded as an ordinary replacement procedure for the toner cartridge.
•
W hen the door is opened, the copier moves the next-to-be-replaced color
toner cartridge to the replacement position.
↓↓↓↓
•
Replace the toner cartridge.
↓↓↓↓
•
The copier enters the toner replenishment confirmation mode after the toner
cartridge is replaced.
NOTE:
If recovery is needed for two colors, the copier proceeds with the next
color if the door is opened or if the user specifies at the operation panel
that the first color should be skipped.
2. If the copier is turned off and on, it assumes that toner cartridges for all colors
have been replaced and enters the toner replenishment confirmation mode for
all colors.
Toner replenishment confirmation mode
1. For color toners, the copier moves the toner cartridge of the first color to be
subject to toner replenishment confirmation to the toner end sensor detection
position (K, then Y, then C, then M). The copier does not use the toner end
sensor for the K toner (it uses VSP). However, it moves the revolver to the toner
end sensor when confirming toner replenishment for the K toner.
2. The copier rotates the toner cartridge for a certain period.
3. The machine checks whether toner is present. For the C, M, and Y toners, the
copier uses the toner end sensor. For the K toner, the copier measures VSP.
4. The copier moves the toner cartridge for the next color to the toner end sensor
detection position and performs steps 2) and 3).
5. When the toner replenishment confirmation cycle ends, the copier moves the
toner cartridges to the detection position for the toner end sensor. The copier
then checks again whether toner is present. If toner is found to be not present,
the copier returns that cartridge to what it was before the toner recovery
procedure started (toner near end or toner end).
6. The copier resets the toner near end and toner end states and resets the toner
end related counters (pixel and sheet counters)for cartridges which the
machine detects to be full.
Toner replenishment confirmation mode takes several seconds for the C, M, and Y
toners and 20 to 30 seconds for the K toner.
2-18
24 February, 1999DRUM UNIT
2.3 DRUM UNIT
2.3.1 OVERVIEW
[D]
[E]
[B][C]
[F]
[A]
A259D201.WMF
[G][H]
[I]
Detailed
Descriptions
[J]
[K]
The drum unit is to the right of the drawer unit. It can easily be removed by pulling
out the drawer unit.
The drum unit consists of the OPC drum [A], the charge corona unit [B], a
quenching lamp [C], the drum potential sensor [D], the ID sensor [E], the carrier
catcher [F], and a cleaning unit [G]. The cleaning unit is integrated in the drum unit
to prevent toner from spilling o ut into the machine.
The cleaning unit is made up of the cleaning blade [H], the lubricant bar [I], the
cleaning brush [J], and the pre-cleaning corona (PCC) [K].
The drum turns anticlockwise as viewed in this drawing.
2-19
DRUM UNIT24 February, 1999
2.3.2 DRIVE MECHANISM
[D]
[C]
[B]
[A]
A259D202.WMF
The drum motor [A] (a brushless motor) drives the drum via gears and a timing
belt. This motor also drives the cleaning unit using a timing belt [C].
This motor contains a drive controller circuit, which controls the drum rotation.
Since the drum shaft does not pass all the way through the drum from front to rear,
a flywheel [D] is mounted on the shaft at the rear of the drum to eliminate uneven
drum rotation.
2-20
24 February, 1999DRUM UNIT
2.3.3 DRUM CHARGE
[B]
[C]
Detailed
Descriptions
A259D203.WMF
[A]
This copier uses a single wire scorotron corona unit to charge the drum.
The single corona wire applies a negative charge to the drum surface (–670 V is
the standard voltage). The stainless steel grid plate [A] makes the corona charge
uniform.
The high voltage supply – C, G [B] supplies a constant voltage (–5 kV) to the
corona wire, and controls the grid voltage.
The charge corona unit contains a cleaner. The wire and grid can be cleaned by
sliding the charge corona unit forward and backward.
The main exhaust fan [C] at the rear of the copier causes air to flow through the
charge corona unit from front to rear. This prevents uneven charging. The air also
flows over the ID sensor, keeping it clean.
2-21
DRUM UNIT24 February, 1999
2.3.4 DRUM CLEANING
[A]
[E]
[C]
[B]
[D]
A259D204.WMF
Pressure is continuously applied to the lubricant bar above the cleaning brush by a
spring [A]. The cleaning brush [B] spreads out the toner remaining on the drum,
which makes it easier for the cleaning blade to remove. The brush collects toner
from the drum surface and the cleaning blade [C] scrapes off the remaining toner
on the drum. The toner falls onto the toner collection coil [D]. The toner collection
coil transports the toner to the used toner tank.
The cleaning blade is angled against drum rotation for improved cleaning
efficiency. The spring [E] maintains a constant downward pressure on the cleaning
blade.
2.3.5 PCC
[A]
A259D206.WMF
The PCC [A] removes uneven charge on the drum, which means that it is not
necessary to make one extra drum rotation before charging. This reduces the copy
time for the first sheet of paper.
2-22
24 February, 1999DRUM UNIT
2.3.6 QUENCHING
[A]
A259D205.WMF
The quenching lamp [A] is a row of LEDs. It turns on immediately after the Start
key is pressed and the drum motor starts. The light is red, to protect the drum from
optical fatigue.
Detailed
Descriptions
2.3.7 CARRIER CATCHER
[A]
There is a magnet [A] below the ID sensor. This removes weakly-magnetic worn
carrier particles from the drum, preventing them from falling on to the copy paper
and causing copy quality problems such as firefly spots.
A259D201.WMF
2-23
SCANNER UNIT24 February, 1999
2.4 SCANNER UNIT
2.4.1 OVERVIEW
[A][B][C][D]
[E]
An image of the original illuminated by the exposure lamp [A] (a halogen lamp) is
reflected onto a color CCD [B] (Charge Couple d Device) via the 1st [C], 2nd [D],
and 3rd [E] mirrors, filter, and lens. The filter removes infra-red from the light
reflected off the original; this is particularly important for glossy photos with black
areas, which can appear reddish in copies.
The number of scans depends on the copy mode (black, full color, auto color
select, or single color). The scanner moves 4 times at most, once for each
development cycle. The order of the cycles is black, yellow, cyan, and magenta.
The CCD is a one-chip color CCD with an RGB color filter. The scanning resolution
is 400 dpi (5,000 pixels).
A259D001.WMF
2-24
24 February, 1999SCANNER UNIT
2.4.2 SCANNER
[C][D]
[A][B][F]
[E]
A259D001.WMF
The 1st scanner consists of the exposure lamp [A], main and sub reflectors [B], and
1st mirror [C]. This model uses a halogen lamp with nine elements. The frosted
surface of the exposure lamp ensures even exposure in the main scan direction.
Detailed
Descriptions
The exposure lamp is energized by a dc supply to avoid uneven light intensity
caused by power fluctuations while the 1st scanner moves in the sub-scan
direction. The sub reflector is shaped so that light will expose the original evenly.
This reduces shadows on pasted originals.
The 1st [C], 2nd [D], and 3rd [E] mirrors have glass on the reverse sides to
increase their weight. This prevents the mirrors from vibrating.
The thermostat [F] in the 1st scanner protects against overheating. It will break at
around 140 °C and cannot be reset.
2-25
SCANNER UNIT24 February, 1999
2.4.3 SCANNER DRIVE
[B]
[A]
[B]
A259D002.WMF
A five-phase stepper motor [A] drives the scanner. This motor drives the 1st [B]
and 2nd [C] scanners via two scanner wires. The wires at the front side and the
rear side are the same, for easy assembly.
In full size mode, the 1st scanner speed is 156 mm/s during scanning, and 1638
mm/s when the scanner returns. The 2nd scanner speed is half that of the 1st
scanner.
Forwarding SpeedReturning Speed
Full Size Mode
Reduction or
Enlargement Mode
156 (mm/s)1638 (mm/s)
156/M (mm/s)1638 (mm/s)
In reduction or enlargement mode, the scanning speed depends on the
magnification ratio (M: 0.25 to 4.00) i.e., 156/M mm/s. The returning speed is
always the same (1638 mm/s). The image length is changed in the sub-scan
direction by changing the scanner speed, and in the main scan direction by image
processing on the scanner IPU board.
The number of scans depends on the color selection mode as shown in the
following table:
Mode
Black and
White
Auto Color
Selection
Single Color
Full Color4
For Black and White
Originals
For Colored Originals
For Y, C, or M1Y, C, M
For G, R, or B
Number of
Scans
1K
1K
4
2
Development Order
K → Y → C → M
Y → C, Y → M, C → M
K → Y → C → M
2-26
24 February, 1999SCANNER UNIT
2.4.4 COLOR CCD
1
R
G
B
5
9
231
5000
A259X001.WMF
Detailed
Descriptions
The color CCD converts light reflected from the original into three analog signals,
one for each of the three basic colors Red, Green, and Blue. The signals are called
the R, G, and B signals. Each of the four scans (for toner colors YMCK) generates
a separate set of three signals (RGB).
The CCD consists of three lines of 5000 elements at a resolution of 400 dpi (15.7
dots/mm). To make the R, G, and B signals, each line has a color separation filter
(R, G, or B). The lines are spaced 4 pixels apart for full size magnification. To
correct for the spacing, the R, G, and B signals must be synchronized. This is done
by delaying the signals in memory buffers on the scanner IPU board (the Image
Processing section contains more details).
The CCD is mounted on the board with the lens block (the assembly is known as
the SBU (Sensor Board Unit). Therefore, to replace the CCD, repla ce the SBU.
2-27
SCANNER UNIT24 February, 1999
2.4.5 WHITE PLATE SCANNING
[A]
[B]
A259D801.WMF
There is a white plate [A] for auto shading, stuck on the exposure glass [B]
underneath the left scale. When this white plate is scanned, the output from all the
CCD elements in a line should in theory be equal, but actually it is no t, for the
following reasons:
•
Variations in sensitivity between elements of the CCD
•
Variations in characteristics of lens and mirror reflectivity
•
Loss of brightness toward the ends of the exposure lamp
To correct for this uneven output from the CCD elements, the light reflected from
the white reference plate is scanned. This is known as auto shading.
Auto shading is done every copy cycle at the scanner home position before starting
the first scan.
2.4.6 SCANNER IPU BOARD
The scanner IPU board processes the RGB signal received from the CCD board
and controls the following under the control of the main control board.
1. Controls exposure lamp on/off switching and voltage
2. Controls the speed of the scanner drive motor
3. Detects the original paper size
4. Controls on/off switching for the scanner exhaust and optics cooling fans
5. Supplies the clock signals for the CCD board
6. Detects when the scanner is at home position
2-28
24 February, 1999SCANNER UNIT
2.4.7 ORIGINAL SIZE DETECTION
[D]
[B]
[C]
[A]
A259D003.WMF
There are three APS sensors (reflective photosensors) in the optics cavity for
original size detection. The original width sensor [A] detects the original width,
while the original length sensors [B] and [C] detect the original length.
The original width sensor [A] and the original length sensor [B] have two internal
beams. Each beam scans a different point of the exposure glass. The other original
length sensor [C] uses only one beam.
If the original or platen cover is present over the scanning point for a particular
sensor, the beam is reflected, and each reflected beam activates a photoelectric
device.
Original Size
A4/A3
Version
(metric)
A311 x 17--11---B410 x 14101---F48
A4-L8
A4-S11 x 8
B5-S11 x 8
B5-L8
A5-L5
LT/DLT
Version
(inch)
1/2
x 140------1
1/2
x 110----1--
1/2
x 110--1----
1/2
x 8
APS1APS2APS3APS4APS5
1/2
1/2
1/2
--10---100----
0--0----See Note
Metric: F4, F, or
Folio, depending
SP5-126-001
on
Detailed
Descriptions
L: Lengthwise S: Sideways
0: No paper, 1: Paper present, --: Don’t care
The diagram on the next page shows where the APS sensors are.
2-29
SCANNER UNIT24 February, 1999
The machine cannot recognize the size of the original on the exposure glass if it is
A5 lengthwise/HLT or smaller. Therefore, when all sensor outputs are off, the
machine either will detect A5 lengthwise/HLT or will display an error message
stating that it cannot detect the size of the original (this depends on SP 4-303).
248.5
273.5
71
62.2
316
273.5
248.5
150
APS3
APS1
APS2
Unit: mm
APS4
APS5
A259D800.WMF
While the main switch is on, these sensors are active and the original size data is
always sent to the main CPU. However, the main CPU checks the data only when
the platen cover is open.
The check starts when the platen cover position sensor ([D] on the previous page)
turns on; this is when the platen is about 15 cm above the exposure glass. At this
time, only the sensors beneath the original receive the reflected light and are on; all
other sensors are off.
The main CPU can recognize the original size from the signals from the sensors. If
a copy is made with the platen open, the main CPU determines the size of the
original from the sensor output at the time that the start key is pressed.
This original size detection method eliminates the necessity for pre-scanning,
which increases the productivity of the machine.
2-30
24 February, 1999SCANNER UNIT
2.4.8 OTHERS
[B]
[A]
[C]
A259D004.WMF
Anti-condensation Heater
There is an anti-condensation heater [A] on the left side of the optical base plate. It
turns on when the main switch is off (if the machine is plugged into the wall outlet),
to prevent moisture from forming on the optics.
Detailed
Descriptions
Fans
Optics Cooling Fan
The optics cooling fan [B] is on the left side of the optics cavity. The fan sends air
into the optics cavity to prevent the exposure lamp and optics cavity from
overheating during copy cycles. This fan is on only when the exposure lamp is on.
Optics Exhaust Fan
The optics exhaust fan [C] is on the right rear side of the optics cavity. This fan
moves air out of the optics cavity to keep it from overheating. This fan is always on
when the main switch is on. During the ready condition, the rotation of the fan
drops to 2/3 of the full speed.
2-31
IMAGE PROCESSING24 February, 1999
2.5 IMAGE PROCESSING
2.5.1 OVERVIEW
+
Scanner IPU Board
CCD
Scanner
Section
IPU
Section
Scanner
PD
+
LD Unit
LD
LD
Drive
Board
LD
Main
Control
Board
Image
Data
Main
Control
Board
Printer
A259X002.WMF
The light from the exposure lamp is reflected by the original onto the CCD board.
The CCD board has a CCD (Charge Coupled Device) with a three-line (RGB) f ilter.
The reflected light is converted to analog image data signals, and these are
transferred to the scanner IPU board.
The scanner IPU board does the following: A/D conversion (to 10-bit data),
shading, D/A conversion for shading compensation, scan line correction, and
image processing. In the IPU section, image data (10 bit) is converted to 8-bit data.
This 8-bit data is sent from the scanner IPU board to the LD main control board.
2-32
24 February, 1999IMAGE PROCESSING
2.5.2 SCANNER SECTION BLOCK DIAGRAM
R
Analog
ASIC
AD
Converter
10bit
10bit
Field
Memory
10bit
G
CCD
B
AGC
Analog
ASIC
AGC
Analog
ASIC
AGC
D/A
Converter
AGC (Auto Gain Control):
Ref
AD
Converter
Ref
AD
Converter
Ref
10bit
CPU
Shading
Circuit
Controls the amplification factor for the signals, using
4 Mbit
Field
Memory
2 Mbit
10bit10bit
the white level signal that is fed back from the shading circuit.
10bit10bit
A259X003.WMF
IPU
Section
Detailed
Descriptions
2-33
IMAGE PROCESSING24 February, 1999
2.5.3 SCANNER SECTION
Photoelectric Conversion (by the CCD)
The color CCD converts the light reflected fro m the original into RGB analog
signals (6.615 MHz for each signal: even-pixel and odd-pixel). Each CCD line has
5,000 pixels and a resolution of 400 dpi (15.7 pixels/mm).
Signal Processing (in the Analog ASIC)
(1) Signal Amplification
Operational amplifiers boost odd-pixel and even-pixel RGB analog signals from the
CCD.
(2) Signal Composition
For each color, the two amplified signals (even-pixel and odd-pixel) are combined
by the multiplexer inside the Analog ASIC before A/D conversion.
(3) Feedback
The CPU on the scanner IPU board receives the white level and black level from
the shading circuits. Then it feeds this data to the clamps and the operational
amplifiers inside the Analog ASIC through the D/A converter (see D/A Conversion).
The CPU updates the black and white level every time the main switch is turned
on.
A/D Conversion
The A/D Converter converts the analog signals (for each RGB color) to 10-bit
digital signals (1024 grades) per pixel.
2-34
24 February, 1999IMAGE PROCESSING
Shading Circuit
[A]
A259D509.WMF
(1) Shading Compensation
Before scanning each original, the machine generates a reference white waveform
(also known as "white shading data") by scanning 5 mm of the white reference
plate [A] in the sub-scan direction (this equals 79 lines at 100% magnification).
Detailed
Descriptions
The white shading data is calculated for each pixel across the main scan. To do
this for a particular pixel, the machine takes the white levels for that pixel on each
of the main scan lines taken from the white reference plate, and calculates a value
from these. The white waveform is made by repeating this process for each pixel
across the main scan.
To improve image reproduction for high-density areas, the machine also measures
the black shading data. It does this by reading the black video level at the first 4
pixels of the CCD, which should be black because these pixels are masked off.
The average of the 4 pixels is represented as the black shading data for one CCD
scan line.
2-35
IMAGE PROCESSING24 February, 1999
White
Correction
Black
Correction
1 line
1023
0
1 line
A259X005.WMF
The shading circuit corrects the video signal for each pixel obtained during image
scanning as follows:
(Video data for each pixel) – (Black shading data for each line)
(White shading data for each pixel) – (Black shading data for each line)
X 1023
The white shading data is updated before every first scanning (2C and 4C mode)
or every scanning (1C mode). The black shading data is updated every scan line.
The white shading data is used to correct the image data for irregularities in the
CCD and in the optics across the main scan. The black shading data is used to
correct the image data for any changes in black level with time, while the machine
scans down the page.
(2) Main Scan Timing
The shading circuit generates the CCD timing signals, and the timing signals for
feeding back the black and white level data from the shading circuit to the Analog
ASIC.
(3) Sub-scan Timing
The shading circuit also generates the synchronization signal for scan line
correction (see the next page for details on this process).
2-36
24 February, 1999IMAGE PROCESSING
D/A Conversion
The CPU monitors the digital feedback signals from the shading circuits and
calculates correction factors. Then the D/A circuit converts the signals from the
CPU into analog signals and feeds them back to the operational amplifiers and the
clamps inside the Analog ASICs. Black shading data is fed back to the clamps to
provide a black level reference. This is done for every CCD pixel to calibra te the
black level, and avoid drifts in the signal with time.
Scan Line Correction
The three CCD lines providing the RGB signals are spaced 4 line s apart on the
original image (when the user selects full size magnification). To compensate for
this discrepancy, the scan line correction circuits synchronize the output timing of
the RGB signals with the IPU section by storing the scan data for each line in
memory. As the discrepancy between RGB video signals changes depending on
the magnification ratio, the correction data is calculated as follows:
Detailed
Descriptions
Enlargement
Reduction
Full Size
B
5 lines5 lines
B
3 lines
B
12345678910111213
GR
4 lines4 lines
GR
3 lines
GR
A259X006.WMF
B: Standard (No correction)
G: (4 lines) x (Magnification ratio)
R: (8 lines) x (Magnification ratio)
If this calculation does not result in an integer, the correction data is set to the
closest integer, but further correction is needed (refer to IPU Section – Picture
Element Correction).
2-37
IMAGE PROCESSING24 February, 1999
2.5.4 IPU SECTION BLOCK DIAGRAM
Panel
Operation
LD
Main
Control
1 bit
γ
Main
•
Printer
Mirror
(gamma)
•
•
Scan
Magnifi-
cation.
8 bit
Color
Conver-
sion
Main
16 bit
2 pixel
Correction
Board
Control
(VRAM)
DRAM
IPU Section
Section
Scanner
3 bit
Auto Text/
•
CPU
Support
ACS
•
Photo
Separation
ASICs
8 bit
Filter• Positive/
•
Field
Memory
Picture
•
Element
Field
Memory
Color
•
Negative
Conversion
8 bit
Field
8 bit
(gamma)
Scanner
Correction
•
γ
Correction
10 bit
8 bit
Memory
Area
DRAM
Treatment
16 MB
CPU
2-38
Circuit
Shading
: A260 machine only
10 bit
A259X007.WMF
24 February, 1999IMAGE PROCESSING
2.5.5 IPU SECTION
Picture Element Correction and Scanner Gamma Correction
(1) Picture Element Correction
R
G
B
A259D803.WMF
Picture Element Correction
The Picture Element Correction circuit does two things.
1. Completion of the Scan Line Correction process
The discrepancy in the spacing of the RGB signals from the CCD in the sub-scan
direction is corrected by the line correction circuit in the scanner section (refer to
Scanner Section – Scan Line Correction). However, if the correction data
corresponding to the magnification ratio is not an integer, then further correction is
needed to synchronize the RGB signals.
Detailed
Descriptions
2. Correction if the CCD is not perpendicular to the light
If the CCD board is not perpendicular to the light axis, the position of each pixel is
different from the original image position. This difference becomes larger towards
the ends. Under this condition, vertical black lines (in the sub-scan direction) at the
left and right edges of the original are colored because the Y, M, and C toner dots
are not properly positioned. (This can be checked by looking at the vertical lines at
the right and left edges of a copy of the C4 color chart.)
Therefore, the CCD line spacing is also corrected here. The target areas for this
correction are shown above. The green CCD line is taken as a standard, and the
ends of the red and blue lines are corrected.
Adjust SP modes 4-932-001 to 4-932-004 to chang e the v erti cal line correction
level.
2-39
IMAGE PROCESSING24 February, 1999
(2) Scanner Gamma Correction (RGB Gamma)
Image Data
1023
0
DarkLight
Fig. 1
Scanner
Input
A259X008.WMF
RGB Signal After
Scanner γ Correction
255
0
Fig. 2
Image
1023
LightDark
Data
A259X009.WMF
The RGB video signals from the CCD are converted to 10-bit digital signals in the
scanner section and sent to the IPU section. These signals are proportional to the
intensity of light reflected from the original image (Fig. 1). However, the IPU section
converts the signal levels as shown in figure 2 by using a gamma (γ) correction
table in order to improve the accuracy of RGB to CMY color conversion, which is
done later in the image process. The same table is used for R, G, and B signals.
The scanner gamma (γ) correction inverts the video signals and converts the signal
from 10-bit to 8-bit as outlined in the following table:
Dark (Black)Light (White)
Scanner Input (RBG)01023
After γ Correction (RGB)
↓
Color Conversion
↓
Printer Output (CMYK)2550
2550
2-40
24 February, 1999IMAGE PROCESSING
ACS (Auto Color Selection)
A259D511.WMF
Auto color selection mode determines if an original is black/white or color. Then
black copy mode or full color mode is automatically selected to match the original.
Detailed
Descriptions
To recognize if the original has a color area or not, the RGB video signals are
compared. If the maximum difference among RGB signal levels (MAX-MIN in the
above diagram) is within a certain range, the pixel is considered black and white.
During the 1st scanning cycle, the latent image is developed with the amount of
black toner specified by the gamma (γ) corrected RGB video signals. If the original
does not have any color areas, the 2nd scanning is aborted and the developed
image is transferred from the transfer belt to the copy paper. Then the black and
white copy comes out. If the original has a color area, copying resumes in the full
color copy mode (4 scans).
Users can maximize the quality of their output by selecting priority for Bk or full
color original in ACS mode, using a User Tool (the default is Bk). The Bk setting
prevents the UCR process from reducing the image density too much in low image
density photo areas. This is explained in more detail in the section on UCR.
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IMAGE PROCESSING24 February, 1999
Auto Letter/Photo Separation
Text Area
A259D512.WMF
In auto text/photo mode, the original image is separated into text and photo areas
(dot screen areas).
"Text" refers to an original or area of an original that contains text and/or line
drawings.
Generally, text areas have strong contrast between the image and the background.
However, photo areas (dot screen areas) have a less extreme range of contrast
levels.
Using these characteristics, the original image is separated into black text areas,
colored text areas, and photo areas. The machine uses the following three
separation methods to detect the different data areas, and the final evaluation
circuit analyzes the output from these three processes to determine the result.
Edge Separation
•
Black Text
•
Colored Text
•
Dot Screen Separation
Colored Text Separation
Photo
A259D513.WMF
(1) Edge separation
The edges of text and line diagram elements are identified by using the following
characteristics: strong contrast, continuity of black or color pixels, continuity of
white pixels around the black or color pixels
The machine can do this by only referring to the green signal.
2-42
24 February, 1999IMAGE PROCESSING
(2) Dot screen separation
Dot screen areas are separated from non-dot screen areas (mainly text).
The machine determines that if white pixels are not detected around the non-white
pixels, it is a dot screen area.
The machine can do this by only referring to the green signal.
(3) Colored text separation
Black pixels and color pixels in text areas are identified by determining the
difference among the RGB maximum signal levels and the output levels of the
RGB video signals.
(4) Final evaluation circuit
The separation signal accompanies the data as it passes to the further stages of
image processing. The separation signal tells the image processing circuits
whether the data is black text, color text, or photo. The text areas are processed in
text mode and the photo areas are processed in photo mode in the subsequent
image processing steps.
Detailed
Descriptions
Auto text/photo separation is mostly effective only for small characters or thin line
diagram elements. If there are large characters or solid line drawing elements in
the original, only the edges of these are processed using text mode; the inner
regions are processed using photo mode.
2-43
IMAGE PROCESSING24 February, 1999
Filtering and Color Conversion
(1) RGB Smoothing Filter
PhotoText
Before
After
A259D514.WMF
A259D515.WMF
A259D521.WMF
Depending on the results of auto text/photo separation (or depending on the
selected original mode), the appropriate software filters are applied to the RGB
video signals. The RGB smoothing filter is applied to photo areas; an edge
emphasis filter is applied to text areas.
(2) Background Density Control and ADS (Auto Image Density Selection)
a. Background Density Control
A259D522.WMF
A259D524.WMF
This function removes low ID image signals (background) that are less than a
certain threshold. The threshold that is applied depends on the color mode (single
color or full color). For each of these modes, the user can select a different
threshold.
2-44
24 February, 1999IMAGE PROCESSING
b. ADS (Auto Image Density Selection)
A259D523.WMF
In ADS mode, the user does not set the threshold; the machine calculates it,
guided by input from the user for F/C and 2C mode (there are 5 settings in the
“User Tools” menu).
Detailed
Descriptions
In full color mode, after the first scanning (Bk) the machine calculates the threshold
for removing background by referring to the RGB data taken from the entire
original.
In black and white mode, the machine detects the background level for the original,
also known as the peak white level, and removes this from the image, to make a
white background. Peak level data is taken for each scan line to correct for
changes in background density down the page. From the peak white level, the
machine determines the white reference value for A/D conversion. Therefore, in
black and white mode the background density is controlled before data is input to
the A/D converter.
(3) Positive/Negative Reverse
In the positive/negative mode, colors are changed to their complements as shown.
Red ↔ Cyan
Green ↔ Magenta
Blue ↔ Yellow
Y
ûû
2-45
R
MC
G
K
B
A259D804.WMF
IMAGE PROCESSING24 February, 1999
(4) Color Conversion
A259D516.WMF
A matrix converts the RGB video signals from each scanning cycle into YMCK
video signals. The content of the matrix depends on the selected mode. The
transparency for each color toner is not ideal, as shown above. Color conversion
compensates for the difference between ideal and actual characteristics.
The following modes affect the matrix: color conversion mode (this is a user mode,
not to be confused with the color conversion process described in this section),
pastel mode, color balance mode, original mode (press print glossy photo, 2nd
generation), RGB toner correction mode.
The following color conversion table is an example of the results from the matrix
operation, for simple color copying without any special modes applied. For
example, to represent green, the yellow and cyan toners are used in a proportion
of 1:1.
Original
Color
Toner
Y11110000
M11000110
C10011100
K10000000
KRYGCBMW
Color Conversion Table
If the user selects a special mode, some of the values in this table may be between
0 and 1. The following page briefly explains the effects of some modes.
2-46
24 February, 1999IMAGE PROCESSING
A. Color conversion mode
Color conversion mode is a user feature, not to be confused with color conversion
(RGB to CMYK) described above. In color conversion mode, a selected color
(C/M/Y/R/G/B/K/W) on an original that falls within the recognized thresholds for that
color is converted into a different color on the copy. Up to 4 colors can be
converted at one time. Convertible colors include C/M/Y/R/G/B/K/W/Yellow
Green/Orange/Marine Blue/Beige/Pink/Purple, and 15 user colors (the user colors
are for A259/A260 only). Changing the matrix parameters enables color conversion
to occur.
For example, when changing Yellow to Black, the coefficients for the Yellow video
signal in the color conversion table become: Y: 1, M: 1, C: 1, Bk: 1
B. Pastel mode
In pastel mode, the matrix parameters change, and the output of the combined
YMCK data shifts to a value between 100 % and 25 %. There are 9 steps, and the
value used depends on the user's selection.
Detailed
Descriptions
C. Color balance mode
In color balance mode, the data output for each color (YMCK) can be changed
independently by changing the matrix parameters. There are nine possible values
for each color.
D. Original mode
There are three modes within photo mode (Press Print, Glossy Photo, and 2nd
Generation) and three types of special original mode (Marker Pen, Inkjet, Map).
The machine selects the most suitable matrix for the original type that is selected
by the user at the operation panel.
For inkjet mode, the user can select one of three different inkjet gamma (γ) tables
to emulate the output of three different types of inkjet printer. (This is done with the
User Tools.)
E. RGB toner correction mode
The toner mixing ratios for R, G, and B are adjustable (SP 5-611-001 to 5-611-
006). The adjustments are valid for 2C (R, G, or B) copy mode only.
F. Twin color mode
Twin color mode separates black areas and colored areas. The machine then
converts black to one color (that was selected by the user) and all the color areas
another color(also selected by the user) so the output has only two colors. For
A258, there are 12 selectable colors. For the A259/A260, there are 15 user colors
in addition to this.
2-47
IMAGE PROCESSING24 February, 1999
(5) UCR (Under Color Removal)
Principle
k
B
k
B
k
B
A259D525.WMF
Obtaining the right colors using YMC toner addition does not always work perfectly.
For example, if the same quantity of toner for each color (YMC) is put on the paper,
ideally the image should become black, but in reality it becomes a dark color, such
as dark blue.
To compensate for this, an equal portion of the common ID value for each color is
subtracted. This reduces the amount of color toner on the paper, and a
proportional amount of black toner is added. This process is known as UCR.
The UCR ratio is the percentage of the common ID value for YMC that is
subtracted and converted to black. In the above example, where the UCR ratio is
100%; the entire common ID value is subtracted from Y, M, and C, and converted
to K.
In actual use, the UCR ratio depends on the color mode and the image density. For
example, when the UCR ratio is 95%, 95% of the entire common ID value is
subtracted from Y, M, and C, and converted to K.
2-48
24 February, 1999IMAGE PROCESSING
Fig. 1
Fig. 3Fig. 4Fig. 5
K
Fig. 6Fig. 7Fig. 8
In this example, the UCR ratio is 70%.
For a Black Image
Fig. 2
K
Detailed
Descriptions
K
A259D526.WMF
When copying a black image, the ID values for all colors are equal (figure 1). For
each color, the ID value is reduced by the amount of the UCR ratio (70% in the
example). A black ID value equal to the 70% reduction is added to compensate for
the color ID reduction (figure 2).
For a Color Image
When copying a color image, the color ID values differ fr om one another (figure 3).
It is treated in two steps.
The ID value for this image is broken down into two parts (figure 4): a set of values
equal to the lowest color ID value, and the remainders of the two higher values.
The part with equal values is treated as a black image (see figures 1 and 2), using
the 70% UCR ratio. The resulting am ounts are then added to the remainde rs from
step 1 (figure 5). The result gives us the ID value for each color and for black
(figure 6).
2-49
IMAGE PROCESSING24 February, 1999
Changes in UCR Ratio with Image Density and Copy Mode
Text Mode
A259D511.WMF
MIN
A259D508.WMF
- Text Areas -
The UCR ratio in text areas is always 100%.
- Photo Areas, with ACS Priority set to Bk -
In photo areas, when the user sets the ACS priority to Bk, UCR begins to replace
color toner with Bk toner at low image densities (when the RGB common value
[MIN] is about 13). This prevents excessive reduction of the image density in low
image density areas.
At this point, the UCR ratio is zero. As shown in the graph at the top right of the
page, it gradually rises with the image density, and the UCR ratio is about 100%
when MIN is 255.
- Photo Areas, with ACS Priority set to Full Color -
When the user se ts the ACS priority to Full Color, the UCR process does not be gin
to replace color toner with Bk toner until a low-medium image density (when MIN is
about 102).
At this point, the UCR ratio is zero. It gradually rises with image density, and the
UCR ratio is about 95% when MIN is 255.
UCA (Under Color Addition)
Using only UCR processing, the copy lacks depth. So, a specified ratio of toner is
always added for each color (YMC only). The amount of additional toner is
proportional to the density of that color on the copy.
2-50
24 February, 1999IMAGE PROCESSING
Main Scan Magnification
A259D527.WMF
The machine changes the scanner speed to reduce or enlarge the original in the
sub-scan direction. However, an LSI on the IPU Board handles reduction and
enlargement in the main scan direction.
Detailed
Descriptions
Scanning and laser writing are done at a fixed pitch (the CCD elements cannot be
squeezed or expanded). So, to reduce or enlarge an image, imaginary points are
calculated that would correspond to a physical enlargement or reduction of the
image. The correct image density is then calculated for each of the imaginary
points based on the image data for the nearest two true points. The calculated
image data then becomes the new (reduced or enlarged) image data.
NOTE:
Mirror Image
The actual calculations for main scan magnification use the polynomial
convolution method. This mathematical process is beyond the scope of a
service manual and will not be covered here.
Main scanMain scan
StartEndEndStart
Sub scan
Sub scan
û
A259D808.WMF
Each line of video data is transferred to the laser unit in reverse (the end of the line
is written on the OPC first).
2-51
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