Ricoh FT7650, FT660 Service Manual

IMPORTANT SAFETY NOTICES

PREVENTION OF PHYSICAL INJURY

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 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. 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.

6.The copier is not attached to the table. Pushing the copier too heard may cause it to drop onto the floor. While moving the copier, push the table.

7. When the main switch is tuned on, the machine will suddenly start turning to perform the developer initialization. Keep hans away from any mechanical and electrical components during this period.

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.

CAUTION



2. The RAM board on the main con trol board has a lithium battery which can explode if replaced incorrectly. Replace the RAM board only with an identical one. The manufacturer recommends replacing the entire RAM board. Do not recharge or burn this battery. Used RAM board must be handled in accordance with local regulations.

SAFETY AND ECOLOGICAL NOTES FOR DISPOSAL

1. Do not incinerate the toner cartridge or the used toner. Toner dust may ignite suddenly when exposed to open flame.

2. Dispose of used toner, developer, and organic photoconductor according to local regulations. (These are non-toxic supplies.)

3. Dispose of replaced parts in accordance with local regulations.

4. When keeping used RAM boards in order to dispose of them later, do not put more than 100 RAM boards per sealed box. Storing larger numbers or not sealing them apart may lead to chemical reactions and heat build-up.

SECTION 1

OVERALL MACHINE

INFORMATION

15 July 1996 SPECIFICATION

1. SPECIFICATION

Configuration: Console Copy Process: Dry electrostatic transfer system Toner Supply Control: Fuzzy Control Photoconductor: OPC drum Originals: Sheet/Book Original Size: Maximum A3/11" x 17" Original Alignment: Left rear corner Copy Paper Size: Maximum A3/11" x 17"

Minimum A5/5

B5/8 A6/5

1/2 1/2 1/2

1/2

" x 8

" (Tray)

" x 11" (1.5 k LCT)

1/2

" x 8

" (By-pass)

Duplex Copying: Maximum A3/11" x 17"

Minimum A5/5

1/2

" x 8

1/2

" (sideways)

Copy Paper Weight: Paper tray: 52 ~ 128 g/m

Bypass feed table: 52 ~ 157 g/m Duplex copying: 64 ~ 104 g/m

, 14 ~ 34 lb

, 14 ~ 42 lb

, 17 ~ 24 lb

Overall

Information

Reproduction Ratios: 4 Enlargement and 6 Reduction

A4/A3 Version LT/LDG Version

200%

Enlargement

Full Size 100% 100%

Reduction

141% 122% 115%

93% 82% 75% 71% 65% 50%

200% 155% 129% 121%

93% 85% 77% 74% 65% 50%

1-1

SPECIFICATION 15 July 1996

Power Source: 115 V, 60 Hz, more than 20 A (for N.A)

220 ~ 240 V, 50 Hz/60 Hz, more than 10 A (for Europe and Asia)

Power Consumption: A175 copier

Copier only Full system*

Warm-up 1.20 kVA 1.22 kVA Stand-by 0.22 kVA 0.24 kVA

Copying 1.40 kVA 1.40 kVA

Maximum 1.70 kVA 1.75 kVA

A176/A191 copiers

Copier only Full system*

Warm-up 1.20 kVA 1.22 kVA Stand-by 0.22 KVA 0.24 kVA

Copying 1.50 kVA 1.50 kVA

Maximum 1.70 kVA 1.75 kVA

A177/A192 copiers

Copier only Full system*

Warm-up 1.20 kVA 1.22 kVA Stand-by 0.22 kVA 0.24 kVA

Copying 1.60 kVA 1.60 kVA

Maximum 1.70 kVA 1.75 kVA

*Full System:

Mainframe with dual job feeder, floor type

•

sorter stapler and 3,500-sheet large capacity tray

Mainframe with recirculating document

•

handler, finisher and 3,500-sheet large capacity tray

1-2

15 July 1996 SPECIFICATION

Noise Emission: Sound Pressure Level:

The measurements are made according to ISO7779

A175 copier Sound pressure level

(The measur ements are made according to ISO 7779 at the operator position.)

Stand-by less than 34 dB (A)

Copying less than 57 dB (A) (average)

Copier only

Overall

Information

Sound power level

A176/A191 copiers Sound pressure level

Sound power level

A177/A192 copiers Sound pressure level

(The measurements are made according to ISO 7779.)

Copier only

Stand-by less than 48 dB (A)

Copying less than 70 dB (A) (average)

(The measur ements are made according to ISO 7779 at the operator position.)

Stand-by less than 34 dB (A)

Copying less than 59 dB (A) (averag e)

(The measurements are made according to ISO 7779.)

Stand-by less than 48 dB (A)

Copying less than 73 dB (A) (average)

(The measur ements are made according to ISO 7779 at the operator position.)

Stand-by less than 36 dB (A)

Copying less than 59 dB (A) (average)

Copier only

Sound power level

(The measurements are made according to ISO 7779.)

Copier only

Stand-by less than 50 dB (A)

Copying less than 73 dB (A) (average)

1-3

SPECIFICATION 15 July 1996

Dimensions:

Width Depth Height

Copier only 690 mm

27.2"

Copier with dual job feeder, sorter stapler, and 3,500-sheet large capacity tray

Copier with dua l jo b fe eder, sorter stapl er w i th punch, and 3,500- sheet large capacity tray

Copier with reci r cul ating document handler, finisher, and 3 ,5 00-sheet large ca pacity tray

1,659 mm

65.4"

1,659 mm

65.4"

1,764 mm

65.9"

690 mm

27.2"

690 mm

27.2 mm" 690 mm

27.2"

690 mm

27.2"

980 mm

38.6"

1,116 mm

43.9"

1,113 mm

43.9

1,112 mm

43.8"

Weight: Copier only:(Without the optional platen cover

= Approximately 2 kg) A175 copier: Approximately 161 kg A176/A177 copiers: Approximately 164 kg A191/A192 copiers: Approximately 167 kg

Zoom: From 50% to 200% in 1% steps Copying Speed:

A175 copier

A176/A191

copiers

A177/A192

copiers

A4/LT (sideways) A3/DLT B4/LG

51 (A4 others) 50 (A4/in France) 50 (LT)

60 31 38

70 36 44

26 32

Warm-up Time: Less than 5 minutes (20°C) (A175 copier)

Less than 5.5 minutes (20°C) (A176/A177/A191/ A192 copiers)

First Copy Time: (A4/81/2: x 11" sideways

3.1 seconds (A175 copier)

2.6 seconds (A176/A177/A191/A192 copiers)

from the 1st feed station)

Copy Number Input: Number keys, 1 to 999 (count up or count down) Manual Image Density

7 steps

Selection: Automatic Reset: 1 minute standard setting; can also be set from 1

second to 999 seconds or no auto reset.

1-4

15 July 1996 SPECIFICATION

Copy Paper Capacity:

By-pass feed table: approximately 50 sheets

•

Paper tray: approximately 550 sheets

•

Tandem tray: approximately 500 sheets

•

Large capacity tray: approximately 1500

•

sheets

Toner Replenishment: 1,100 g/cartridge Optional Equipment:

Platen cover (A528-04)

•

Dual job feeder (A610)

•

Recirculating document handler (A607)

•

20 bin sorter stapler (Floor type) (A606-17:

•

Ricoh, -22: NRG, -15: Savin, -26: Infotec) Finisher (A608)

•

3500-sheet Large capacity tray (A609)

•

Receiving Tray (A446-05)

•

Key Counter Bracket D (A509-03)

•

20 bin sorter stapler (Floor type) with punch

•

(A606-57, -67: Ricoh, -52, -62: NRG -66: Infotec, -55: Savin)

Overall

Information

Guidance ROM KIT (A627)

•

Editing sheet (spare part)

•

1-5

MACHINE CONFIGURATION 15 July 1996

2. MACHINE CONFIGURATION

2.1 COPIER OVERVIEW

There are three types of mainframe.

A175 copier

Four 550-sheet paper trays

Optional 3,500-sheet large capacity

tray

550 550

(3,500)

550 550

A176V500.img

A176/A177 (U.S.A., Asia) copiers

Tandem paper tray

(including two 500-sheet paper tray)

One 550-sheet paper tray

1,500-sheet built-in large capacity

tray

Optional 3,500-sheet large capacity

tray

500 x 2 or 500

(3,500)

550

1,500

A176V501.img

1-6

15 July 1996 MACHINE CONFIGURATION

A191/A192 (Europe) copiers

Tandem paper tray

Three 550-sheet paper trays

Optional 3,500-sheet large capacity

tray

500 x 2 or 550

(3,500)

550 550 550

A176V500.img

Overall

Information

1-7

MACHINE CONFIGURATION 15 July 1996

2.2 SYSTEM OVERVIEW

DJF version

(Mainframe type (A175/A176/A177 (U.S.A.), A175/A191/A192 (EU)) with dual job feeder and floor type sorter stapler. The mainframe in the illustration below is the A176.)

Dual job feeder (A610)

Floor type sorter stapler (A60617) or

3,500-sheets large capacity tray (A609)

Floor type sorter stapler with punch (A60657, A60667)

A176V502.img

RDH version

(The mainframe (A175/A176/A177 (U.S.A.), A175/A191/A192 (EU)) with recirculating document handler and finisher. The mainframe in the illustration below is the A176.)

Recirculating document handler (A607)

Finisher

(A608)

3,500-sheets large capacity tray (A609)

A176V503.img

1-8

15 July 1996 MACHINE CONFIGURATION

MEMO

Overall

Information

1-9

COPY PROCESS AROUND THE DRUM 15 July 1996

3. COPY PROCESS AROUND THE DRUM

A176V504.wmf

1. OPC DRUM

The organic photo conductive (OPC) drum (100 mm diameter) has high resistance in the dark and low resistance under light.

2. DRUM CHARGE

In the dark, the charge corona unit gives a uniform negative charge to the OPC drum. The charge remains on the surface of the drum. The amount of negative charge on the drum is proportional to the negative grid bias voltage applied to the grid plate on the charge corona unit.

3. EXPOSURE

An image of the original is reflected to the OPC drum surface via the optics section. The charge on the drum surface is dissipated in direct proportion to the intensity of the reflected light, thus producing an electrical latent image on the drum surface.

The amount of charge remaining as a latent image on the drum depends on the exposure lamp intensity controlled by the exposure lamp voltage.

4. ERASE

The erase lamp illuminates the areas of the charged drum surface that will not be used for the copy image. The resistance of drum in the illuminated areas drops and the charge on those areas dissipates.

1-10

15 July 1996 COPY PROCESS AROUND THE DRUM

5. DRUM POTENTIAL SENSOR

The drum potential sensor detects the electric potential on the drum to compensate image processing elements.

6. DEVELOPMENT

Positively charged toner is attracted to the negatively charged areas of the drum, thus developing the latent image. (The positive triboelectric charge of the toner is caused by friction between the carrier and toner particles.)

The development bias voltage applied to the development roller shaft controls two things:

1) The threshold level if toner is attracted to the drum or toner remains on the development roller.

2) The amount of toner to be attracted to the drum.

The higher the negative development bias voltage is, the less toner is attracted to the drum surface.

7. PRE-TRANSFER LAMP (PTL)

The PTL illuminates the drum to remove almost all the negative charge from the exposed areas of the drum. This makes image transfer easier.

8. IMAGE TRANSFER

Paper is fed to the drum surface at the proper timing so as to align the copy paper and the developed image on the drum surface. Then, a negative charge is applied to the reverse side of the copy paper by the transfer belt, producing an electrical force which pulls the toner particles from the drum surface onto the copy paper. At the same time, the copy paper is electrically attracted to the transfer belt.

Overall

Information

9. PAPER SEPARATION

Paper separates from the OPC drum by the electrical attraction between the paper and the transfer belt. The pick-off pawls help to separate the paper from the drum.

10. CLEANING

The cleaning brush removes toner remaining on the drum after image transfer and the cleaning blade scrapes off all the remaining toner.

11. QUENCHING

Light from the quenching lamp electrically neutralizes the charge potential of the drum surface.

1-11

MECHANICAL COMPONENT LAYOUT 15 July 1996

4. MECHANICAL COMPONENT LAYOUT

511

39 38

12 13

15 16 17 18

19 20 21

22 23

24 25

1-12

26 27

A176V505.wmf

15 July 1996 MECHANICAL COMPONENT LAYOUT

Overall

Information

1. 3rd Mirror

2. 2nd Mirror

3. 1st Mirror

4. Exposure Lamp

5. Lens

6. Cleaning Brush

7. Cleaning Blade

8. Quenching Lamp

9. Charge Corona Unit

10. OPC Drum

11. 6th Mirror

12. 4th Mirror

13. 5th Mirror

22. Registration Rollers

23. Transfer Belt

24. Vertical Transport Rollers

25. Tandem Tray 550-sheet Tray

26. Universal Tray

27. 1500-sheet LCT 550-sheet Tray

28. Toner Collection Bottle

29. Transfer Belt Cleaning Blade

30. Hot Roller

31. Pressure Roller

32. Jogger Fences

33. Duplex Positioning Roller

14. Erase Unit

15. Drum Potential Sensor

16. Toner Hopper

17. Development Unit

18. Pre-Transfer Lamp

19. Pick-up Roller

20. Feed Roller

21. Separation Roller

34. Duplex Pick-up Roller

35. Duplex Feed Roller

36. Separation Belt

37. Junction Gate

38. Exit Rollers

39. Optics Cooling Fan

40. 550-sheet Tray

1-13

DRIVE LAYOUT 15 July 1996

5. DRIVE LAYOUT

❶

❷

❾

❽

❼

3 4 5

❸

❻

❺

❹

Main Motor

❶

Scanner Drive Motor

❷

Fusing/Duplex Drive Motor

❸

Paper Feed Motor

❹

Toner Collection Motor

❺

Registration Clutch

❻

By-Pass Feed Motor

❼

BY-Pass Feed Clutch

❽

Development Drive Motor

❾

A176V506.wmf

1. OPC Drum

2. Scanner Unit

3. Transfer Belt Unit

4. Paper Exit Unit

5. Fusing Unit

6. Duplex Unit

7. Paper Trays

8. Paper Feed Units

9. Toner Hopper

10. Development Unit

11. Cleaning Unit

1-14

15 July 1996 PAPER PATH

6. PAPER PATH

6.1 STANDARD COPYING

[F]

[E]

[D]

[C]

[B]

[A]

Overall

Information

A176V507.wmf

Paper feed begins from the exterior LCT, by-pass feed table or paper feed stations in the paper tray unit. The copy paper then follows one of two paths inside the copier. The path followed depends on which mode the operator has selected. For copy processing, all sheets follow the same paths from the paper feed mechanism [A] through the registration rollers [B], transfer belt [C], and fusing unit [D]. After that, copies are delivered to the sorter bins [E] or proof tray [F], however, 2 sided copies are diverted for further processing.

1-15

PAPER PATH 15 July 1996

6.2 MULTIPLE 2-SIDED CO PYI NG

a. Front Side

[D]

[A]

[B]

[C]

A176V508.wmf

b. Rear Side

A176V509.wmf

In this mode the junction gate [A] directs sheets exiting the fusing unit to the duplex tray entrance. After that, all sheets follow the path through the duplex entrance rollers [B].

After all front side copying is completed, the sheets on the duplex tray are fed in order from the bottom to the top and follow the path through the duplex feed mechanism and vertical transport rollers [C] to the registration rollers [D]. After that, these sheets follow the same path as standard copying from the registration rollers to the sorter.

1-16

15 July 1996 ELECTRICAL COMPONENT DESCRIPTION

7. ELECTRICAL COMPONENT DESCRIPTION

Refer to the electrical component layout on the reverse side of the attached Point to Point for symbols and index numbers.

Symbol Name Function Index No.

Motors

M2 M3 Main Drives the main unit components. 44

M4 Develop ment Drive Drives the development unit. 45 M5 By-pass Fe ed Drives the by-pass feed rollers. 46 M6 3rd Scanne r Dr i ve Drives the 3rd scanner (dc steppe r) 47

M10 Lens Horizontal Drive Shi f ts the lens horizontal position. 51 M11 Lens Vertical Drive Shifts the lens vertical position. 52 M12 Optic Cooling Fan Removes heat from the optics unit . 53

M13

M14

M15

M16

M17

M18

M19

M20

M21

Scanner Drive Drives the 1st and 2nd scanners (dc

servo).

Exhaust Fan Removes the heat fr om ar ound the

fusing unit.

Toner Bottle Drive Rotates the toner bottle to supply

toner to the toner hopper.

Charge Wire Cleaner Drive

Jogger Drives the jogger fences to square the

Fusing/Dupl ex Drive Drives the fusin g uni t , the duplex unit,

Paper Feed Drives all feed and transpor t rol l ers in

1st Lift Raises the bottom plate in the 1st

2nd Lift Raises the bottom plate in the 2nd

Toner Collec tion Transports the col l ected toner to the

3rd Lift (4 Tray version only)

Side Fence Drive (Tandem vers i on only)

Rear Fence Drive (Tandem vers i on only)

LCT Motor (1,500 Tray ver si on only)

Drives the main charge wire cleaner to clean the charg e w i re .

paper stack in the duplex tray (dc stepper).

and the paper exi t r ol le r s.

the paper tray uni t.

paper tray.

toner collecti on bottle. Raises the bottom plate in the 3rd

paper tray. Opens and closes the front and the

rear side fences of th e ta ndem tray. Moves the paper s st acked in the left

tandem tray to the right tandem tray. Lifts and lowers the LCT bottom plate

to bring paper to t he f eed position and allow loading of the paper.

127

Overall

Information

1-17

ELECTRICAL COMPONENT DESCRIPTION 15 July 1996

Symbol Name Function Index No.

M22

M23

M24

M25

M26

AC Drive Cooling Fan (60/70 CPM version only)

Optic Cooli ng Fan-2 (60/70 CPM version only)

Duplex Cool i ng Fan Cools the paper on the duplex tray to

Drum Cooling Fan (70 CPM versio n onl y)

4th Lift (4 Tray version only)

Remove heat from around the AC drive unit.

Remove heat from the optic unit.

reduce the heat around the drum. Cools the drum unit t o remove the

heat from the duplex tray. Raises the bottom plate in the 4th

paper tray.

141

142

*143A, B

144

151

* (A: 60/70 CPM, B: 50/5 1 C P M )

Magnetic Clutches

MC1

Toner Supply Turns the toner supply ro l le r to supply

toner to the devel opment un it.

57 MC2 Registration Drives the r egi stration rollers. 58 MC3

By-pass Feed Starts paper feed from the by- pass

feed table.

Duplex Transport D rives the duplex transport rollers to

MC4

transport the pap er to the vertical

transport rollers.

MC5

MC6

MC7

MC8

MC9

Duplex Feed Starts paper feed from the dupl ex tray

to the du plex transport rollers.

1st Feed Starts paper feed from the 1st feed

tray.

2nd Feed Starts paper feed from the 2nd feed

tray.

3rd Feed Starts paper feed from the 3rd feed

tray.

4th Feed (4 Tray version only)

Starts paper feed from the 4th feed tray.

101

104

152

Switches

SW1

SW2

SW3

SW4

SW5

By-pass Table Det ect s i f the by-pass feed table is

open or closed.

Front Door Safety Cuts the ac power line and detect s i f

the front door is open or not.

1st Tray Set

Detects if the 1st tray is set or not. (Non-Tandem version only)

2nd Paper Size Determines what size paper i s i n th e

2nd (universal) paper tray. Toner Overflow Detects w hen the toner collection

bottle is full.

1-18

15 July 1996 ELECTRICAL COMPONENT DESCRIPTION

Symbol Name Function Index No.

SW6 SW7 Lo w er F ront Door Safety Detects if the front door is open or not. 83 SW8 SW9 Mai n Provides powe r to the copier 122

SW10

SW11

Solenoids

SOL1

SOL2

SOL3

SOL4

SOL5

SOL6

SOL7

SOL8

SOL9

SOL10

SOL11

SOL12

Toner Collection Bottle Set

3rd Tray Set (4 Tray version only)

Tray Down (1500 Tray vers i on only)

4th Tray Set (4 Tray version only)

Junction Gate Moves the junction gate to direct

Duplex Positioning Controls the up-down movem e nt of

By-pass Pick-u p Controls the up-down movem ent of

Guide Plate Opens the guide plate when a pap er

Transfer Belt Posi tio ni ng Controls the up-d ow n m ovement of

Pressure Arm Presses th e paper on the dupl ex t ray

Tandem Lock Locks the left tandem feed tray and

1st Pick-up Controls the up-down movem ent of

1st Separation Rol l er Controls the up-d ow n m ovement of

2nd Pick-up Controls the up-down movement of

2nd Separatio n R ol l er Controls the up-down movement of

3rd Pick-up Controls the up-down movement of

Detects if the toner collection bottle is

set or not.

Detects if the 3rd tray is set or not.

Lowers the LCT bot t om pl at e.

Detects if the 4th tray is set or not.

copies to the duplex tray or to the

paper exit.

the positioning roller.

the pick-up rol l er for by- pass feed.

misfeed occurs around th is area.

the transfer belt unit.

against the dupl ex feed rollers.

separates the ri ght and left tandem

trays.

the pick-up rol l er in the 1st feed

station.

the separation r ol l er i n the 1st feed

station.

the pick-up roller in the 2nd feed

station.

the separation r ol l er i n the 2nd feed

station.

the pic k-up roller in the 3r d f eed

station.

126

149

100

102

103

105

Overall

Information

1-19

ELECTRICAL COMPONENT DESCRIPTION 15 July 1996

Symbol Name Function Index No.

3rd Separation Ro ll er Controls the up-down movement of

SOL13

the separation r ol l er i n the 3rd feed

106

station.

SOL14

4th Pick-up (4 Tray version only)

Controls the up-down movement of

the pic k-up roller in the 4t h f eed

153

station.

SOL15

4th Separation Rol l er (4 Tray version only)

Controls the up-down movement of

the separation r ol l er i n the 4th feed

154

station.

Sensors

Scanner HP Informs the CPU when the 1st and

2nd scanners are at th e home position .

Platen Cover Position-1 Informs the CPU that the platen cover

is in the up or down po sition (related

to APS/ARE function). Platen Cover Position-2 Informs the CPU that the platen cover

is in the up or down po sition to detect

if the original has been removed or not.

Lens Vertical HP Informs the CPU that the lens is at the

full-size posi t i on. Lens Horizont al H P Informs the CPU t hat th e l ens is at the

horizontal home position. 3rd Scanner HP Informs the CPU when the 3rd

scanner is at the hom e position. By-Pass Paper End Informs the CPU that there is no

paper in the by-pass feed table. Guide Plate Position Informs the CPU if the registration

guide plate is closed or not. Jogger HP Detects if the duplex jogger fen ces

are at the home po si t i on or not .

Vertical Transport Detects the leading edge of the paper

S10

to determine the paper feed timi ng of

the next sheet. Duplex Exit Detects the leadi ng edge of the paper

S11

to determine the duplex transpor t

clutch on timing. Duplex Entranc e Sensor Detects the leadi ng edge of the paper

S12

to determine the duplex feed clut ch off

timing.

S13 Duplex Paper End Detects paper in the dup l ex t ra y. 13

Duplex Transport D et ect s t he l eading edge of t he paper

S14

to control the jogger motor and the

positioning sol enoid on timing.

S15 Exit Detects misfee ds. 15

1-20

15 July 1996 ELECTRICAL COMPONENT DESCRIPTION

Symbol Name Function Index No.

S16 Fusing Exit Detects misfeeds. 16 S17 Paper Guide Detects misfeeds. 17

S18 S19 Original Length-1 Detects original length. 21

S20 Original Length-2 Detects original length. 22 S21 Original Width Detect s or i gi nal width. 23

S22

S23

S24 S25 Toner Near End Detects toner end condi t i on. 30 S26 S27 Drum Potential Detects the drum surface potentia l . 39 S28

S29

S30

S31

S32

S33

S34

S35

S36

S37

S38

S39

Auto Image Density Senses the background density of the

original.

By-Pass Paper Size Informs the CPU what size paper is in

the by-pass feed table. Toner Density Senses t he amount of toner in the

black develop er . Registratio n Detects misfeeds and control s

registration clutch off-on tim ing.

Auto-Response Returns the displ ay from the scree n

saver.

Image Density Detects the density of th e ID sensor

pattern on the drum. 1st Pape r End Informs the CPU when the 1st

cassette runs ou t of paper. 1st Pape r Near End I nforms the CPU when t he 1st

cassette is in nea r end condition. 1st Paper Feed Controls t he 1st paper feed clu tc h

off/on timing and the 1st pick-up

solenoid off ti m i ng. 2nd Paper Near End Informs the CPU when the 2nd

cassette is in nea r end condition. 1st Lift Detects the correct feed height of th e

1st cassette. 2nd Paper End Informs the CPU when the 2nd

cassette runs ou t of paper. Toner Collec tion Motor Detects the toner col l ect i on motor

operation. 2nd Lift Detects the correct feed height of th e

2nd cassette. 3rd Lift Detects the correct feed height of the

3rd cassette. 3rd Paper Near End

(4 Tray version only) 3rd Paper End Informs the CPU when the 3rd

Informs the CPU when the 3rd

cassette is in nea r end condition.

cassette runs ou t of paper.

Overall

Information

1-21

ELECTRICAL COMPONENT DESCRIPTION 15 July 1996

Symbol Name Function Index No.

3rd Paper Feed Controls the 3rd paper feed clutch

S40

off/on timing and the 3rd pick-up

solenoid off ti m i ng. 2nd Paper Feed Controls the 2nd paper feed clut ch

S41

off/on timing and the 2nd pick-up

solenoid off ti m i ng.

S42

Base Plate Down (Tandem vers i on only)

Detects when the bottom plate is

completely lowered to stop the 1st lift

motor.

S43

S44

S45

S46

S47

S48

S49

S50

S51

S52

S53

S54

Side Fence Positioning (Tandem vers i on only)

Rear Fence Retur n (Tandem vers i on only)

Rear Fence HP (Tandem vers i on only)

Left Tandem Paper En d (Tandem vers i on only)

LCT Near End (1,500 Tray ver si on only)

Tray Down (1,500 Tray ver si on only)

Tray Paper Set (1,500 Tray ver si on only)

Side Fence Close (Tandem vers i on only)

4th Lift (4 Tray version only)

4th Paper Near End (4 Tray version only)

4th Paper End (4 Tray version only)

4th Paper Feed (4 Tray version only)

Informs the CPU when the tandem

tray side fences are open.

Informs the CPU when the tandem

tray rear fence is i n th e return position.

Informs the CPU when the tandem

tray rear fence is i n th e home position .

Informs the CPU when the left tandem

tray runs out of paper.

Detects the paper near end conditi on.

Detects when the tray is completely

lowered to stop the LCT motor.

Informs the CPU when the paper is

set on the LCT botto m tr ay.

Detects whether the side fence close

or not.

Detects the correct feed height of th e

4th cassette.

Informs the CPU when the 4th

cassette is in nea r end condition.

Informs the CPU when the 4th

cassette runs ou t of paper.

Controls the 4th pa per feed clutch

off/on timing and the 4th pick-up

123

124

125

150

145

146

147

148

solenoid off ti m i ng.

PCBs

PCB1

AC Drive Provides AC power to the exposure

lamp and fusing lamp.

PCB2 Main Controls all machine functions. 109 PCB3 Optic Con trol Controls all op tics components. 110

PCB4

PCB5

Development Bi as Control

Paper Feed Cont rol Controls all components i n t he paper

Controls the outp ut of development

bias.

bank.

1-22

108

111

112

15 July 1996 ELECTRICAL COMPONENT DESCRIPTION

Symbol Name Function Index No.

PCB6 DC Power Supply Unit Provides DC power. 113 PCB7 Guidance Controls the guidance display. 120

PCB8

Lamps

L1 L2 Fusing Provides heat to the hot roller. 32 L3

Operation Panel Controls the LED matrix, and monitors

the key matrix.

Exposure Applies high intensity light to the

original for exposure.

Quenching Neutralizes any charge remaining on

the drum surface a fter cl eaning. Erase Discha r ges the drum outside the

image area. Pre-transfer Reduces the charge on the drum

surface before tr ansfer.

121

Overall

Information

Power Packs

Transfer Provides high voltage for the transfer

PP1

Charge Provides high vo ltage fo r t he charge

PP2

Others

TS1

TF1

TH1

TH2

TH3

RA1 Main Power Relay Controls main power. 107

Optics Therm oswitch Opens the exposure lam p ci r cui t i f the

Fusing Therm of u se Opens the fusing lamp circuit i f the

Fusing Therm i st or Senses the tempera ture of the hot

Optics Therm i st or Monitors the temperature of the optics

Drum Thermistor (Located on the ID Sensor Ass’y)

Transfer Anti-Condensation

Optics Anti-Condensation Turns on when the main switch is off

belt and controls t he t ransfer belt

positioning solenoid.

corona wires, and t he grid plate.

Controls QL, PTL, and charge wire

cleaner motor functions.

optics unit overheats.

fusing unit overheats.

roller.

cavity.

Monitors the temperature of the OPC

drum. 41

Turns on when the main switch is off

to prevent moisture from forming on

the transfer belt.

to prevent moisture from forming on

the optics.

117

119

1-23

ELECTRICAL COMPONENT DESCRIPTION 15 July 1996

Symbol Name Function Index No.

CO1 NF1 Noise Filter Removes ele ct rical noise. 115

CB1

LA1

Total Counter Keeps track of the total number of

copies made.

Circuit Breake r Provides back-up high current

protection for the electrical

components. Lightening Arrestor Removes current surges from the AC

input lines.

114

116

118

1-24

SECTION 2

DETAILED SECTION

DESCRIPTIONS

15 July 1996 PROCESS CONTROL

1. PROCESS CONTROL

1.1 OVERVIEW

Image Density Control

ADS Pattern

Original Scale

(Fuzzy Control)

Pattern

Latent Image Control

Detailed

Descriptions

Latent image Control

Exposure Control

Charge Control

Drum Thermistor

Lamp Voltage

Grid Voltage

Paper

Pattern

VL Pattern

Original Exposure Glass

Erase Lamp

Drum Potential Sensor

Toner Supply On time

Development. Bias

TD Sensor

ID Sensor

Image Density Control

(Fuzzy Control)

Toner Supply Control

Main PCB

A176D500.wmf

This model uses two process control methods. One compensates for variation in the drum potential (latent image control) and the other controls the toner concentration and toner supply amount (image density control).

2-1

PROCESS CONTROL 15 July 1996

1.1.1 Latent Image Control

Charge

Exposure

Black

White

Erase

A176D501.wmf

Potential Sensor

Drum

The figure shows the changes of the drum potential during the copy process.

: The drum potential just after charging the drum.

(Dark Potential): The drum potential just after exposing the black

pattern (V

(Light Potential): The drum potential just after exposing the white

pattern (V

(Residual Voltage): The drum potential just after the exposure of the

pattern)

erase lamp.

After long usage following installation or a PM, drum potential will gradually increase due to the following factors:

Dirty optics or exposure lamp deterioration Dirty charge corona casing and grid plate Change of the drum sensitivity

In this copier, the change in drum potential is detected by the drum potential sensor and the following items are controlled to maintain good copy quality.

The grid bias voltage The exposure lamp voltage The development bias voltage.

A drum thermistor detects the drum temperature and this data is also used to control the above voltages. It is impossible to explain simply because it is controlled by methods developed in our laboratories using an artificial neural network.

2-2

15 July 1996 PROCESS CONTROL

1.1.2 Image Density Control

Image density is controlled by the following sensors:

Toner density sensor (TD sensor) Image density sensor (ID sensor)

Data from the TD sensor is used to keep the toner concentration in the developer at a constant level. However, the image on the OPC drum varies due to the variation of toner chargeability (influenced by the environment) even if the toner concentration is constant. By the ID sensor compensation, toner concentration is changed to keep the image density on the OPC drum constant.

The following items are controlled to maintain a constant copy image density:

Toner supply clutch on time

Detailed

Descriptions

Toner supply level data (V

REF

) of the TD sensor

2-3

PROCESS CONTROL 15 July 1996

1.2 PROCESS CONTROL DATA INITIAL SETTING

The following flow chart shows all the steps that will be performed whenever the machine is turned on while the hot roller temperature is below 100°C. This initializes all the process control settings.

Main SW On (Fusing Temp. < 100°C)

Charge wire cleaning (if more than 5 k copies are made since last cleaning)

Drum Potential Sensor Calibration

①

Drum Conditioning Start (Fusing Temp. = 180°C)

VSG Adjustment

Transfer belt voltage detection

VR Measurement

VD/VL Correction

TD Sensor Detection

②

ID Sensor Detection/Correction

③

ADS Adjustment

① : See Latent Image Control section

(Page 2-5) for details.

② : See Image Density Control section

(Page 2-12) for details.

③ : See Optics section (Page 2-39) for details.

2-4

15 July 1996 PROCESS CONTROL

1.3 LATENT IMAGE CONTROL

1.3.1 Drum Potential Sensor Calibration

Case Sensor

[A]

Drum

A176D503.wmf

Output

Amp.

Detailed

Descriptions

[B]

Main PCB

A176D502.wmf

The drum potential sensor [A] is located just above the development unit. The sensor has a detector which detects the strength of the electric field from the electric potential on the drum. The output of the sensor depends on the strength of the electric field.

Since the output of the sensor is affected by environmental conditions, such as temperature and humidity, the sensor output is calibrated during process control data initial setting.

The High Voltage Control PCB [B] has two relay contacts. Usually RA602 grounds the drum. However, during the initial setting, the main PCB turns RA601 on and RA602 off and applies the voltage to the drum shaft.

By measuring the output of the drum potential sensor when –100 V and –800 V are applied to the drum, the sensor output is calibrated automatically. (The machine recognizes the relationship between actual drum potential and the potential sensor output.)

2-5

PROCESS CONTROL 15 July 1996

1.3.2 Drum Conditioning

When the fusing temperature reaches 180°C, the machine starts the drum conditioning process. In this mode, the main motor, main charge corona, erase lamp and development bias are activated for about 30 seconds and

drum sensitivity and residual voltage (V

) are stabilized, as in continuous

copy runs.

1.3.3 V

Adjustment

During drum conditioning, the ID sensor checks the bare drum’s reflectivity and calibrates the output of the ID sensor to 4 ± 0.2 V.

1.3.4 V

Measurement

[–V]

New Drum Used Drum

Drum Potential

Dark

LightOriginal Density

A176D504.wmf

The above figure shows the relationship between the drum potential and the original density. To get constant copy quality, this relationship must be maintained.

Since this relationship tends to change to the one represented by the dotted line by various factors, compensations are required.

The residual voltage (V voltage is increased. Therefore, the V

) cannot be compensated even if the exposure lamp

change has to be compensated by

other means. The main control board checks the drum potential just after the erase lamp

exposure by the drum potential sensor after drum conditioning. This measured drum potential is in fact V

and VL corrections.

. This VR is used as the standard for the

NOTE:

In the figure above, the residual voltage (V

) for the new drum is 0 V.

Actually, there is some residual voltage even on the new drum.

2-6

15 July 1996 PROCESS CONTROL

1.3.5 VD Correction

Exposure

[–V]

Drum Potential

–770

Dark

New Drum

VD Pattern

Glass

A176D505.wmf

Compensated

Detailed

Descriptions

After many copies

LightOriginal Density

A176D506.wmf

The drum potential just after the black pattern (V

Pattern) is exposed (VD: Dark Potential) tends to lower during drum life due to a decrease in the drum’s capacity to carry a charge.

To check the actual V

pattern (Black) stuck on the bottom side of the exposure glass bracket is

, the first scanner moves to the home position and the

exposed on the drum.

The main control board measures V adjusts it to a target value by adjusting the grid bias voltage (V

On the other hand, there is a change of the drum residual voltage (V that the target V

Target V

Value: VD = VR + (–770)

voltage is compensated as follows:

The adjusted grid bias voltage (V

through the drum potential sensor and

GRID

) is kept in memory until the next

process control data initial setting.

), so

2-7

PROCESS CONTROL 15 July 1996

1.3.6 VL Correction

Exposure Glass

[–V]

VL Pattern

and V

Compensated

A176D505-2.wmf

Drum

Only V Compensated

Potential

New Drum

–770

–140

Dark LightOriginal Density

A176D507.wmf

Dirty optics and/or exposure lamp deterioration decreases the intensity of the light that reaches the drum. In addition to this, the drum sensitivity also changes during the drum’s life. These factors change the drum potential just

after white pattern exposure (V

To check the actual V

pattern (White) stuck underneath the original scale is exposed on the

, the lens moves to the VL pattern check position. The

: Light Potential).

drum.

The main control board measures V adjusts it to a target value by adjusting the exposure lamp voltage (V

The residual voltage (V

) change also affects VL, so that VL’s target voltage

through the drum potential sensor and

LAMP

is compensated as follows:

Target V

Value: VL = VR + (–140)

The adjusted exposure lamp voltage (V next process control data initial setting.

2-8

LAMP

) is stored in memory until the

15 July 1996 PROCESS CONTROL

1.3.7 VR Correction

[–V]

Development Bias (V

)

Drum Potential

–770

and VL Compensated

New Drum

–140

Potentials (V

Dark

, VD, VL) are monitored by the potential sensor. (This is done

Original Density

Light

A176D508.wmf

only when the fusing temperature is less than 100°C after the machine is turned on.) During the check cycle, the V

and VL patterns are exposed and the drum potential on the area where exposed by each pattern is checked by the potential sensor.

Compare the curve of the V

and VL compensated drum potential with the curve of the new drum, they are parallel but the compensated potential is still higher (V increased residual potential, development bias (V

) than the new drum potential. To prevent dirty backgrounds due to

) is applied as follows:

Detailed

Descriptions

= VR + (–220)

2-9

PROCESS CONTROL 15 July 1996

1.3.8 Initial Setting Sequence

The following graph shows the sequence of events during process control data initial setting.

for the purpose of ADS sensor correction

Exposure Lamp

Potential

800

100

New V

Sensor Output

1. Potential sensor

2. V

R’

, VD’, VL’

potential

3. VD, V correction

4. ID sensor pattern potential

Latent Image Control

A176D509.wmf

1. Potential sensor calibration By measuring the output of the drum potential sensor when –100 V and

100

–800 V are applied to the drum, the sensor output (V

and V

calibrated automatically (See page 2-5 for details).

800

) is

2. V

, VD, VL potential detection After about 30 seconds of drum conditioning, V developed by using the previous grid bias voltage (V exposure lamp voltage (V

The machine calculates the new V detected V

, VD, VL data.

LAMP

) data to detect the VR, VD, VL data.

GRID

and V

2-10

and VL Patterns are

GRID

) data and

LAMP

data using the

15 July 1996 PROCESS CONTROL

3. VD and VL corrections Using the calculated V

GRID

and V

developed again and the new V

LAMP

data, VR, VD, and VL patterns are

, VD, and VL data are detected.

If both V

and VL data are within specifications, the new V

GRID

, V and development bias (VBB) are determined based on the new VD, VL, and V

values.

Specifications:

= –770 + VR ± 20 V

= –140 + VR ± 20 V

is outside specifications, V

If V is measured again and V The same is done for V

and V The above process continues until both V The graph on the previous page shows the example when only V outside specifications at the first V specifications after one V

GRID

is shifted one step. Then the VD pattern

is detected again.

LAMP

and VL fall within specifications.

detection and it became within

correction (V

LAMP

was

is changed 0.5V/step , V

changed 20V/step).

100

If V

if V

or VL do not fall within specifications after V the maximum or minimum level, the machine stops V uses the previous V

or V

800

at drum potential sensor calibration is outside specifications or

GRID

and V

LAMP

values during copying.

GRID

LAMP

or V

or VL correction and

are shifted to

In this case, nothing is indicated on the machine but the SC counter is incremented.

LAMP

GRID

Detailed

Descriptions

Related SC codes (see troubleshooting section for details):

Code Condition

361 Incomplete drum potential sensor calibrati on

364 Abnormal V 365 Abnormal V 366 V

abnormal

detection

Development bias is also decided by using VR as follows.

= VR + (–220)

4. ID sensor pattern potential detection

This is performed to determine ID Sensor Bias Voltage. The details are explained in the development control section (see page 2-16).

2-11

PROCESS CONTROL 15 July 1996

1.4 IMAGE DENSITY CONTROL

1.4.1 Toner Density Sensor

A: V B: V C: V

OUT

(Gain dat a) is high .

OUT

is within the specification.

OUT

(Gain dat a) is

low.

A176D531.wmf

OUT

= VIN x = 12 x

Main PCB

AGC

Gain

256

Gain

256

OUT

(12 V)

V GND

Sensor Output

TD Sensor

A176D510.wmf

Developer consists of carrier particles (iron) and toner particles (resin and carbon). Inside the development unit, developer passes through a magnetic field created by coils inside the toner density sensor. When the toner concentration changes, the voltage output by the sensor changes accordingly.

When new developer with the standard toner concentration (2.0% by weight, 20 g of toner in 1000 g of developer) is installed, developer initial setting must

be performed by using SP mode ( SP Adjustment - PAGE 1). During this setting, the output voltage (V

OUT

) from the auto gain control circuit (AGC) on the main control board PCB varies to change the output voltage from the toner density (TD) sensor. This is done by changing the gain data, see below.

OUT

= VIN x

Gain Data

If the data is high, V

256

OUT

= 12 x

becomes high, and the sensor output voltage

Gain Data

256

becomes high. As a result, the sensor characteristic becomes as illustrated by curve A. If the data is low, V

OUT

becomes low, and the sensor output voltage becomes low. As a result, the sensor characteristic shifts as illustrated by curve C.

2-12

15 July 1996 PROCESS CONTROL

By selecting the proper gain data, the sensor output is set within the targeted control le vel (V

REF

, V

REF

= 2.5 ± 0.1 V). Now, the sensor characteristic is

illustrated by curve B and the TD sensor initial setting is completed. The selected gain data is stored in memory, and V

OUT

from the auto gain

control circuit stays constant during the toner sensor detection cycle.

At every copy cycle, toner density in the developer is detected once. The sensor output voltage (V toner supply level voltage (V

) during the detection cycle is compared with the

REF

Detailed

Descriptions

2-13

A176D511.wmf

PROCESS CONTROL 15 July 1996

To stabilize toner concentration, toner supply amount (toner supply clutch on time) is controlled by referring to V

REF

and VTD. The toner supply amount is calculated at every copy. The toner supply amount is determined by using the following factors.

① ②

REF

– V

– VTD’(VTD’ = VTD of the previous copy cycle)

A176D512.wmf

By referring to these factors, the machine recognizes the difference between the current toner concentration and the target toner concentration. The machine also understands how much toner concentration has changed and predicts how much the toner supply amount will probably change. By changing the toner supply amount precisely, toner concentration (image density) is kept at a constant level. Since the toner supply clutch on time updating is under fuzzy control, the relation among V

, VTD’, V

REF

cannot be expressed by a simple algebraic

formula.

REF

Correction>

The image on the OPC drum changes due to variation of toner chargeability (influenced by the environment) even if the toner concentration is constant. The image density sensor (ID sensor) directly checks the image on the OPC drum and shifts V

REF

data (under fuzzy control) to keep the image on the

OPC drum constant, as explained in the next section.

NOTE:

1) Toner end condition is detected by the toner end sensor (see the development section for details).

2) The toner supply clutch turns on at the intervals between each copy process while image development is not performed.

2-14

15 July 1996 PROCESS CONTROL

1.4.2 Image Density Sensor Detection

[B]

[C]

Drum

[A]

bias

A176D513.wmf

and VSP are checked by the ID sensor [A]. The ID sensor is located

A176D514.wmf

underneath the drum cleaning section. There is no ID sensor pattern in the optics, however, a pattern image is made on the OPC drum by the charge corona unit [B] and the erase lamp [C].

is the ID sensor output when checking the erased drum surface.

is the ID sensor output when checking the ID sensor pattern image.

Detailed

Descriptions

To compensate for any variation in light intensity from the sensor LED, the reflectivity of both the erased drum surface and the pattern on the drum are checked.

VSP Detection

1st Series of

V Detection

is detected every time the machine starts copying.

During V

Copies (8 copies)

V Detection

detection, the development sleeve rollers do not rotate and no

2nd Series of Copies (5 copies)

Detection

V Detection

3rd Series of Copies (17 copies)

Detection

A176D515.wmf

V Detection

development bias is applied.

is detected after copying is completed if 10 or more copies have been made since V when checking V

was last detected. Since the transfer belt must be released

, a VSP check cannot be done during continuous copying.

2-15

PROCESS CONTROL 15 July 1996

①

Potential

–700 V

①

Sensor Detection

②

ID Sensor Bias Level

③

–300

IDB

= VP +300 (V)

②

4.0 V

③

ID Sensor Output

A176D517.wmf

A176D516.wmf

While developing the ID sensor pattern, ID sensor bias is applied. ID sensor bias is determined during process control data initial setting as follows:

Apply charge while grid voltage is –700 V to create the ID sensor pattern. Check the drum potential (V

) of the latent image created by the charge with

–700 V grid.

IDB

Adjust the ID sensor bias (V

IDB

= VP – (–300) (V)

+ 300 (V)

= V

Change the bias to the calculated V

adjustment sequence in the process control data initial setting and V

V are used to determine V

IDB

is not changed until the next process control data initial setting is done.

REF

correction timing>

REF

) so that it satisfies the following formula.

IDB

and detect VSP. VSG detected during

data at process control data initial setting.

After the series of copies is completed in the case that 10 or more copies have been made, V

, VSP and the current TD sensor output (VTD).

Since this V

REF

, V

REF

’, VSG, VSP and VTD cannot be expressed by a simple algebraic

REF

is updated by referring to the previous V

data updating is under fuzzy control, the relationship among

REF

formula.

’),

REF

is updated not only at the above case. But also during developer initial

V setting and during process control data initial setting.

2-16

15 July 1996 PROCESS CONTROL

1.4.3 Sensor Abnormal Conditions

a. ID sensor (V Whenever V

REF

data and toner concentration is controlled only by using TD sensor

SG,VSP

falls under 2.5 V or VSP rises over 2.5 V, the CPU fixes the

) abnormal

output.

and VSP are still detected as usual during abnormal conditions and if

output returns to normal levels (V

≥ 2.5 V, VSP ≤ 2.5 V), the CPU returns

the toner concentration control to normal mode. b. TD sensor (V Whenever V

) abnormal

rises over 4.0 V or VTD falls under 0.5 V, the CPU shifts the toner supply to the fixed supply mode. In this condition, the CPU never stops the toner supply. The fixed toner supply amount can be changed in four steps (4%, 7%, 11%, 14%) by using SP mode. The default fixed toner supply amount is 4%.

is still detected as usual during the abnormal condition and if its output

V returns to a normal level, the CPU returns the toner concentration control to normal mode.

c. Drum Potential Sensor abnormal

Detailed

Descriptions

Whenever V rises over 4.2 V or V

100

rises over 0.7 V or V

800

falls under 2.7 V, the CPU also shifts the toner

supply to the fixed supply mode, as for a TD sensor (V

100

falls under 0.1 V or whenever V

) abnormal condition.

Related SC codes. (See troubleshooting section of details.):

Code Condition

351 Abnormal V 352 Incomplete TD Sensor Initial Set t i ng 353 Abnormal VSP Detection (VSP > 2.5 V) 354 355 Abnormal V 356 Abnormal V 357 Abnormal V 358 Abnormal V 361 Incomplete Drum Potential Sensor Calibration

Abnormal V

Detection (VSG > 4.2 V)

Detection (VSG ≤ 2.5 V)

Detection (VTD > 4 V)

Detection (VTD < 0.5 V)

SP/VSG SP/VSG

Detection (VSP/V Detection (VSP/VSG < 0.025)

SG ≥

0.25)

800

2-17

DRUM UNIT 15 July 1996

2. DRUM UNIT

2.1 OVERVIEW

113 15

7. 8 6

A176D518.wmf

The drum unit consists of the components as shown in the above illustration. An organic photoconductor drum (diameter: 100 mm) is used for this model.

1. OPC Drum

2. OPC Drum Protective Shutter

3. Erase Lamp

4. Drum Potential Sensor

5. Pre-transfer Lamp

6. Pick-off Pawl

9. Cleaning Brush

10. Toner Collection Coil

11. Cleaning Blade

12. Ozone Filter

13. Cleaning Filter

14. Charge Power Pack

7. Image Density Sensor

8. Drum Thermistor

15. Quenching Lamp

16. Main Charge Corona Unit

2-18

15 July 1996 DRUM UNIT

2.2 OPC DRUM CHARACTERISTICS

An OPC has the characteristics of:

1. Being able to accept a high negative electrical charge in the dark. (The

electrical resistance of a photoconductor is high in the absence of light.)

2. Dissipating the electrical charge when exposed to light. (Exposure to light

greatly increases the conductivity of a photoconductor.)

3. Dissipating an amount of charge in direct proportion to the intensity of the

light. That is, where stronger light is directed to the photoconductor surface, a smaller voltage remains on the OPC.

4. Being less sensitive to changes in temperature (when compared to

selenium F type drums).

5. Being less sensitive to changes in rest time (light fatigue). This makes it

unnecessary to compensate development bias voltage for variations in rest time.

Detailed

Descriptions

2-19

DRUM UNIT 15 July 1996

2.3 DRUM CHARGE

2.3.1 Overview

[A]

A176D519.wmf

This copier uses a double corona wire scorotron system for drum charge. Two corona wires are required to give sufficient negative charge on the drum surface because of a rather high drum speed (330 mm/s.). The stainless steel grid plate makes the corona charge uniform and controls the amount of negative charge on the drum surface by applying the negative grid bias voltage.

The charge power pack [A] gives a constant corona current to the corona wires (–1100 µA) and bias voltage to the grid plate is automatically controlled to maintain proper image density according to the change of the OPC drum potential due to dirty grid plate and charge corona casing.

2-20

15 July 1996 DRUM UNIT

2.3.2 Air Flow Around the Dr um

[A]

[C]

Detailed

Descriptions

[B]

A176D520.wmf

The exhaust fan [A] located above the fusing unit provides an air flow to the charge corona unit to prevent uneven built-up of negative ions that can cause an uneven charge of the drum surface as shown.

An ozone filter [B] absorbs the ozone (O

) around the drum.

The exhaust fan rotates slowly during stand-by and rotates quickly during copying to keep the temperature inside the machine constant.

70 CPM machine has another fan (drum cooling fan), which is located at the right rear side of machine (front view). The drum cooling fan cools the drum unit to remove the heat from the duplex tray. To prevent foreign matters from entering the copier inside, a dust protection filter is installed in the entrance [C] of the duct.

2-21

DRUM UNIT 15 July 1996

2.3.3 Charge Wire Cleaning Mechanism

[A]

[C]

[A]

[C]

[B]

A176D521.wmf

The flow of air around the charge corona wire may deposit toner particles on the corona wires. These particles may interfere with charging and cause low density bands on copies.

The wire cleaner pads [A] automatically clean the wires to prevent such a problem.

The wire cleaner is driven by a dc motor [B]. Normally the wire cleaner [C] is located at the front end position (home position). After 5000 or more copies are made and fusing temperature is less than 100°C after the main switch is turned on, the wire cleaner motor turns on to bring the wire cleaner to the rear end and then back to the home position.

When the wire cleaner moves from the rear to the home position (black arrow in the illustration), the wire cleaner pads clean the wires.

There are no home position and return position sensors. The CPU monitors the input voltage (5 V). When the wire cleaner reaches the end, it is stopped and the motor is locked. At this time, input voltage slightly decreases (to about 4 V) and the CPU judges to rotate the motor in reverse.

2-22

15 July 1996 DRUM UNIT

2.4 ERASE

2.4.1 Overview

Detailed

Descriptions

A176D522.wmf

: Lead edge erase margin 3.5 ± 2.5 mm

: Side erase margin total of both sides 3 mm or less Lo: Original width Lc: Charged width of drum

: Lead edge erase

Es: Side erase

The erase lamp unit consists of a line of 123 LEDs extending across the full width of the drum, the width of each being about 2.5 mm. In editing mode, the appropriate LED’s turn on according to the customer’s designation.

2-23

DRUM UNIT 15 July 1996

2.4.2 Lead Edge and Trail Edge Erase

The entire line of LEDs turns on when the main motor turns on. They stay on until the erase margin slightly overlaps the lead edge of the original image on the drum (lead edge erase margin). It prevents the shadow of the original lead edge from appearing on the copy paper. This lead erase margin is also necessary for the lead edge of the copy paper to separate from the hot roller. The width of the lead edge erase margin can be adjusted by SP mode ( SP Adjustment - PAGE 3).

When the scanner reaches the return position, the charge corona, the grid bias, and the exposure lamp turn off. However, the charged area on the drum surface is a little longer than the actual original length in order to have the entire latent image of the original. The entire line of LEDs turn on when the trail edge of the latent image has passed under the erase lamp unit. This prevents developing unnecessary parts of the drum surface, reducing toner consumption and drum cleaning load. The LEDs stay on to erase the lead edge of the latent image in the next copy cycle. After the final copy, the erase lamps turn off at the same time as the main motor.

2.4.3 Side Erase

Based on the combination of copy paper size and the reproduction ratio data, the LEDs turn on in blocks. This prevents the shadow of the original side edge and unexposed front and rear sides of the drum surface in reduction mode from being developed. This reduces toner consumption and drum cleaning load.

In the DJF mode, the horizontal original standard position on the exposure glass is 5 mm away from the rear scale. In the RDH mode, the horizontal center of the original is aligned with the center of the exposure glass. On the other hand, the horizontal original standard position on the exposure glass in the platen cover mode is the rear scale edge. To erase the shadow made by the edge of the rear scale in platen cover mode, one more LED at the front side turns on. This is in addition to the LED’s on in DJF and RDH modes.

2-24

15 July 1996 DRUM UNIT

2.5 CLEANING

2.5.1 Overview

[C]

[D]

A176D523.wmf

[A]

[B]

Detailed

Descriptions

4 mm

A176D524.wmf

This copier uses the counter blade system for drum cleaning. The blade [A] is angled against drum rotation. This counter blade system has the following advantages:

•

Less wearing of the cleaning blade edge.

•

High cleaning efficiency.

Due to the high efficiency of this cleaning system, the pre-cleaning corona and cleaning bias are not used for this copier.

The cleaning brush [B] is used to support the cleaning blade. The brush collects toner from the drum surface and scraped by the cleaning blade. Toner on the cleaning brush is scraped off by the mylar [C] and falls to the toner collection coil [D]. Toner is transported to the toner collection bottle by the toner collection coil.

To remove the accumulated toner at the edge of the cleaning blade, the drum turns in reverse for about 4 mm at the end of every copy job. The accumulated toner is removed by the cleaning brush by this action.

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DRUM UNIT 15 July 1996

2.5.2 Drive Mechanism

[C]

[A]

[E]

[B]

[D]

A176D525.wmf

The drive force from the main motor is transmitted to the cleaning unit drive gear via the timing belt [A] and the cleaning unit coupling [B]. The cleaning unit drive gear [C] then transmits the force to the front side through the cleaning brush [D]. The force at the front side is used for the toner collection coil gear [E].

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15 July 1996 DRUM UNIT

2.5.3 Cleaning Blade Pressure Mechanism and Side-to-Side Movement

[C]

[A]

[D]

Detailed

Descriptions

[B]

A176D526.wmf

The spring [A] always pushes the cleaning blade against the OPC drum. The cleaning blade pressure can be manually released by pushing up the release lever [B]. To prevent cleaning blade deformation during the transportation, the release lever is locked in the pressure release (upper) position.

The pin [C] at the rear end of the cleaning blade holder touches the cam gear [D] which gives a side-to-side movement to the blade. This movement helps to disperse accumulated toner to prevent early blade edge deterioration.

2-27

DRUM UNIT 15 July 1996

2.5.4 Toner Collection Mechanism

[E]

[D]

[B]

[G]

[F]

[A]

[C]

A176D527.wmf

Toner collected by the cleaning unit is transported to the toner collection bottle [A] through the toner collection tubes. Three helical coils are used for toner transport.

One coil [B] is driven by the main motor via drive belts and the other coil [C] is driven by an independent toner collection drive motor [D].

The actuator disk [E] on the toner collection drive motor monitors the proper rotation of the toner collection coil [C] to prevent the coil from being damaged by toner clogged in the collection tube. The main PCB monitors the sensor output and increases the motor speed if the sensor monitors that the toner collection motor rotates at a speed lower than normal. Also, the CPU will display an SC 342 if no signal changes (ON → OFF) are detected for more than 2.55 seconds while the toner collection motor is turning.

When the toner collection bottle [A] become full, the toner pressure in the bottle increases and presses the gear [F] against the toner overflow switch [G]. After the toner overflow switch is activated, the finishing of the copy job, or up to 100 continuous copies, is allowed, then copying is prohibited and the service call "full toner collection bottle" indication is displayed on the LCD.

This condition can be cleared by de-actuating the toner overflow switch while de-actuating then actuating the toner collection bottle switch ([C] in next page).

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15 July 1996 DRUM UNIT

[B]

[A]

A176D528.wmf

[C]

Detailed

Descriptions

A176D529.wmf

2.5.5 Pick-off mechanism

The pick-off pawls are always in contact with the drum surface with weak spring pressure. They move side to side during the copy cycle. This movement is made via a shaft [A] and an eccentric cam [B].

2.5.6 Toner Collection Bottle Set Detection

The toner collection bottle set switch [C] prohibits machine operation by indicating SC343 while the toner collection bottle is not set.

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DRUM UNIT 15 July 1996

2.6 QUENCHING

[A]

A176D530.wmf

In preparation for the next copy cycle, light from the quenching lamp (QL) [A] neutralizes any charge remaining on the drum.

The quenching lamp consists of a line of 16 LEDs extending across the full width of the drum.

Yellow colored LEDs are used for QL to reduce ultra violet light which would cause light fatigue on the OPC drum.

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15 July 1996 OPTICS

3. OPTICS

3.1 OVERVIEW

[E]

[A]

[B]

[D]

A176D532.wmf

The optics unit reflects an image of the original on the exposure glass onto the OPC drum. This forms a latent electrical image of the original.

Detailed

Descriptions

[C]

On this model a halogen lamp (85 V 200 W: A175 copier, 225 W: others) is used for the exposure lamp [A]. Lamp surface is frosted to ensure even exposure.

Six mirrors are used to make the optics unit smaller and obtain the wide reproduction ratio range (50 ~ 200%).

The lens [B] is driven by two stepping motors for (1) vertical direction (parallel to the paper feed direction) and (2) horizontal direction movements.

To correct focal length change in reduction and enlargement modes, the third scanner unit [C] (4th and 5th mirrors) position is changed by a stepping motor.

The toner shielding filter [D] is green (a green filter partly absorbs red light) to improve red original duplication.

The optic anti-condensation heater [E] (located on the optic base plate) turns on while main switch is turned off to prevent the moisture from forming on the optics.

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OPTICS 15 July 1996

3.2 SCANNER DRIVE

[C]

[A]

[B]

[D]

[E]

A176D533.wmf

A dc servo motor is used as the scanner drive motor [A]. Scanner drive speed is 330 mm/s (A175 coper) or 430 mm/s (others). during scanning, and 1,950 mm/s (50/51, 60 CPM versions) or 2,670 mm/s (70 CPM version) when the scanner goes back.

The scanner drive motor drives the first [B] and second scanners [C] using two scanner drive wires via the timing belt [D] and the scanner drive shaft [E]. The second scanner speed is half of the first scanner speed.

The scanner drive wire is not directly wound around the pulley on the scanner drive motor.

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15 July 1996 OPTICS

3.3 VERTICAL LENS DRIVE

[B]

[A]

Detailed

Descriptions

Enlarge

HP (100%)

Reduce

steps30 303030

A176D535.wmf

A176D534.wmf

(Enlarge → HP) (Reduce → HP)

(Enlarge → Enlarge) (Reduce → Reduce) (Enlarge → Reduce)

(Reduce → Enlarge)

The lens vertical drive motor [A] changes the lens vertical position in accordance with the selected reproduction ratio.

A stepping motor (approx. 0.095 mm/step) is used to drive the lens through the lens drive belt. The maximum lens vertical shift distance is 290 mm (from the position at 50% to the position at 200%).

The lens vertical home position sensor [B] detects the lens vertical position for full size mode. The optic control PCB keeps track of the lens position based on the number of pulses sent to the lens vertical drive motor.

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OPTICS 15 July 1996

3.4 HORIZONTAL LENS DRIVE

[A]

A176D536.wmf

steps

Enlarge

Reduce

A176D537.wmf

The original horizontal position on the exposure glass varies depending on the mode (such as platen, DJF and RDH modes) for easy original handling. However, the center is the standard position for paper feed.

Therefore, the lens horizontal position has to be changed according to paper size, reproduction ratio, original feed modes and the edit modes (centering, margin adjust, etc.).

A stepping motor (approx. 0.07 mm/step) is used to drive the lens through the lens drive belt.

The lens horizontal home position sensor [A] is used to detect the lens horizontal position for A4/LT sideways, in full size and platen mode.

The other positions are determined by counting the number of motor drive pulses.

Since this model has a horizontal lens drive mechanism, side-to-side registration adjustment for each feed station can be done easily by using SP

mode ( SP Adjustment - PAGE 4).

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15 July 1996 OPTICS

3.5 HORIZONTAL LENS POSITIONING

3.5.1 For Original Position

Platen DJF

Copy Paper

RDH (Cente r)

Horizontal

Lens Position

[A]

[C]

[B]

Detailed

Descriptions

A176D538.wmf

A176D539.wmf

There are three standard original positions for the platen, DJF and RDH modes.

In platen mode, the original is aligned with both the rear [A] and the left [B] original scales (rear left corner [C] is the standard position).

In RDH mode, the original position is the center of the left scale [B]. In DJF mode, the original position is 5 mm to front of the platen mode original

position to maintain the original transport path (5 mm from the rear scale). The above figure shows the lens horizontal positions for each original mode

when identical size paper is used.

3.5.2 For Paper Size

Original Rear Edge

Lens Position

Copy Paper

Horizontal

A176D540.wmf

To keep high paper feed performance, the center is assigned as the paper feed standard position. Therefore, the lens horizontal position is changed according to the paper size.

The figure shows the lens horizontal position for each paper size in full size mode.

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OPTICS 15 July 1996

3.5.3 For Reproduction Rati o

Original Rear Edge

Original

200%

100%

50%

100%

3rd Scanner Position

200%

Copy Paper

A176D541.wmf

When the reproduction ratio is changed, the vertical position of the lens is changed. At the same time, the total focal length has to be changed to adjust the image focusing. For this focal length change, the horizontal position of the 3rd scanner is also adjusted. The maximum 3rd mirror shift distance is 50 mm (from the position at 100% to the position at 50, 200%).

The figure shows the lens horizontal position for 50, 100 and 200%.

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15 July 1996 OPTICS

3.6 3RD SCANNER DRIVE

[B]

[A]

Detailed

Descriptions

A176D542.wmf

(Initialize)

(Reduce/Enl arge → HP)

(Reduce/Enl arge → Reduce/Enl ar ge) (Reduce/Enl ar ge → Reduce/Enl ar ge)

(Reduce/Enl ar ge → Enlarge/Redu ce)

40 steps

A176D543.wmf

To compensate the focus for reproduction and lens position changes, the 3rd scanner (4th and 5th mirrors) position is changed.

A stepping motor [A] (approx. 0.095 mm/step) is used for the 3rd scanner drive.

The 3rd scanner home position sensor [B] is used to detect the unit position for full size mode. The optic control PCB keeps track of the unit position based on the number of motor drive pulses.

2-37

OPTICS 15 July 1996

3.7 OPTICS CONTROL CIRCUIT

Sensors

Encoder

Data

Main Control Board

Bus

Main CPU

Exposure Lamp

Optics Control Board

Optics Control CPU

AC Drive Board

Optic Thermistor

A176D544.wmf

Scanner Drive

Horizontal Lens Drive

Vertical Lens Drive

3rd Scanner Drive

Optic Cooling Fan

The optic control board communicates with the main board through a data bus. The optics control board monitors all the sensor signals, encoder output, thermistor output and controls all motors in the optics.

At the programmed time, the main CPU sends a scanner start signal to the optics control CPU.

The CPU generates a pulse-width modulation (PWM) signal. The PWM signal goes to a driver circuit, which sends drive pulses to the scanner drive motor.

An encoder in the scanner drive motor generates pulse signals. A speed/direction control circuit monitors the scanner speed and the direction of the signals, and uses this data to regulate the motor speed.

The home position sensor monitors the position of the scanner. When the main switch is turned on, the main CPU confirms the position of the scanner by moving the scanner out of the home position and back again. This data is sent to the optics control CPU.

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15 July 1996 OPTICS

3.8 AUTOMATIC IMAGE DENSITY CONTROL SYSTEM (ADS)

[B]

[A]

Detailed

Descriptions

A176D545.wmf

In ADS mode the original background density is sensed by the ADS sensor [A] and the main CPU determines an appropriate development bias voltage for the original to prevent dirty backgrounds from appearing on copies.

The ADS sensor board is mounted on the rear side of the optics side plate. The sensor board is covered by the sensor housing cover which has a small hole to direct the reflected light from the original to the ADS sensor.

The ADS sensor standard voltage is adjusted to 2.7 V when process control data initial setting is performed. The exposure lamp turns on with ID level 4 at the home position and the light reflected by the ADS pattern [B] (white painted) reaches the ADS sensor. The main CPU adjusts the ADS gain data automatically to make the output 2.7 V. This gain data is stored in the RAM board.

2-39

OPTICS 15 July 1996

90 mm

20 mm

ADS Sensor Output

[V]

Peak hold

A = M = 1.0 (m = 50 ~ 100)

M = B =

ADS Original Voltage

9.7

(mm)

100

8.25

(m = 101 ~ 200)

x 100 (mm)

m m: reproduction ratio

(50 ~ 200)

A176D546.wmf

For the first scanning of an original in ADS mode, the CPU starts sampling of the ADS sensor output while exposing the ADS pattern at the scanner home position. Then the CPU stores the maximum ADS sensor output as a reference voltage. This means that every ADS check cycle, the first scanning for the original, the ADS reference voltage is renewed by the latest exposure light reflected by the ADS pattern.

In the full size mode, the CPU samples the ADS sensor output when the scanner scans the original from 9.7 mm to 18 mm from the left scale edge. The CPU takes the maximum ADS sensor output during the sampling period and compares it with the ADS reference voltage to determine the proper development bias voltage. (See development bias control section for details.)

The sampling length of ADS sensor output for the original differs depending on the reproduction ratio because the scanner speed is different.

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15 July 1996 OPTICS

3.9 MANUAL IMAGE DENSITY CONTROL

When the image density is set manually, the voltage applied to the exposure lamp changes as shown in the table below.

Lighter Darker

–90 Dev. Bias Voltage (negative)

Exposure Lamp Voltage

V V

LAMP

LAMP LAMP

LAMP

VBB –60

+4.5 +3.0

+0.5

LAMP

–1.5 –3.5

Detailed

Descriptions

LAMP

–5.5

76 4 21

A176D547.wmf

: Exposure lamp voltage at ID level 4.

This value is determined at process control data initial setting.

: Development bias (negative) voltage at ID level 4.

This value is determined at process control data initial setting.

Manual ID Position

2-41

OPTICS 15 July 1996

3.10 UNEVEN LIGHT INTENSITY CORRECTION

[D]

A176D548.wmf

exposure intensity

original

illumination

Shading plate

distribution

[A] [B]

[C]

A176D549.wmf

The entire exposure lamp surface is frosted to ensure even exposure. To compensate for reduced light at the edge of the lens, a shading plate is

placed in front of the lens. The shading plate is fixed to the lens unit. The shading plate compensates the light intensity when the lens horizontal position is shifted ([A] to [C]).

Also three shading mylars [D] intercept any diffused reflected light from outside the light path.

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15 July 1996 OPTICS

3.11 ORIGINAL SIZE DETECTION IN PLATEN MODE

[B]

[C]

Detailed

Descriptions

[A]

A176D551.wmf

[E]

[D]

A176D550.wmf

There are three reflective sensors (APS sensors) in the optics cavity for the original size detection. Original width Sensor [A] is used for sensing the original width and Original Length Sensor-1 [B] and Original Length Sensor-2 [C] sense the original length.

Inside each APS sensor, there is an LED [D] and three photoelectric devices [E]. The light generated by the LED is broken up in three beams and each beam scans a different point of the exposure glass. If the original or platen cover is present over the scanning point, the beam is reflected and each reflected beam exposes a photoelectric device and activates it.

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 opened.

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OPTICS 15 July 1996

[A]

A176D552.wmf

Original Size Length Sensor 1 Length Sensor 2 Width Sensor

A4/A3 versionLT/DLT version123456789

A3 11 x 7 OOOOOOOOO B4 10 x 14 XOOOOOOOO

—8

F4 8 x 13 XXOOOOOOX A4-L 8 B5-L — XXXOOOOXX A5-L 5 B6-L — XXXXOOXXX A6-L — XXXXXOXXX A4-S 11 x 8 B5-S — XXXXOOOOO A5-S 8 A6-S — XXXXXXXXX

1/2

x 14 XOO—O—OO X

1/2

x 11 XXXOOOOOX

1/2

x 8

x 5

1/2

XXXOOOXXX

XXXOOOOOO

XXXXXOOXX

NOTE:

-L: Lengthwise

-S: Sideways Sensors #4 and #6 are not used for LT/DLT version machines.

The check is done when the platen position sensor [A] turns on. This is when the platen is positioned about 15 cm above the exposure glass. At this time, only the sensor(s) located underneath the original receive the reflected light and are on. Other sensor(s) are off. Through the on/off data of the nine (seven for LT/DLT version machine) sensors, the main CPU can recognize the original size.

In case the copy is made with the platen open, the main CPU decides the original size only through the data when the Print key is pressed.

This original size detection method eliminates the necessity for a pre-scan and increases the machine’s productivity.

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15 July 1996 OPTICS

3.12 HALF TONE MODE

Detailed

Descriptions

A176D553.wmf

This machine has a half tone mode. In this mode, which can be select in the operation panel, the charge corona grid voltage is decreased by 200 V but the charge corona grid voltage might blank out low density areas of the original. To correct this, the exposure lamp voltage is decreased by 3 V. As a result, the image density is lowered for picture or half tone original.

2-45

DEVELOPMENT 15 July 1996

4. DEVELOPMENT

4.1 OVERVIEW

[C]

[B]

[D]

[A]

A176D554.wmf

This copier uses a double roller (diameter 20 mm each) development (DRD) system. This system differs from single roller development systems in that (1) it develops the image in a narrower area, (2) it develops the image twice, and (3) the relative speed of each development roller against the drum is reduced. Also, finer toner (Approx. 9 µm) and developer (Approx. 70 µm) are used. Both the DRD system and new supplies improve the image quality, especially of thin horizontal lines, the trailing edges of the half-tone areas, and black cross points.

The paddle roller [A] picks up developer in its paddles and transports it to the upper development roller [B]. Internal permanent magnets in the development rollers attract the developer to the development roller sleeve. The upper development roller carries the developer past the doctor blade [C]. The doctor blade trims the developer to the desired thickness and creates backspill to the cross mixing mechanism.

The development rollers continues to turn, carrying the developer to the OPC drum [D]. When the developer brush contacts the drum surface, the negatively charged areas of the drum surface attract and hold the positively charged toner. In this way, the latent image is developed.

The development roller is given a negative bias to prevent the toner form being attracted to the non-image areas on the drum surface that may have a slight residual negative charge.

After turning another 100 degrees, the developer is returned to the paddle roller [A].

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15 July 1996 DEVELOPMENT

4.2 DRIVE MECHANISM

[D]

[C]

[E]

[A]

[B]

A176D555.wmf

The gears of the development unit are driven by the development drive gear [A] when the development motor [B] (dc servomotor) turns.

The gears of the toner hopper are driven by the toner supply roller drive gear [C] when the toner supply clutch [D] activates.

The above gears are helical gears. Helical gears are more quiet than normal gears. The teeth of the development drive gear are chamfered so that they smoothly engage with the development roller gear [E] when the unit is installed.

Detailed

Descriptions

2-47

DEVELOPMENT 15 July 1996

4.3 CROSSMIXING

[A]

[B]

A176D556.wmf

[C]

[B]

[A]

[E]

[F] [D]

[C]

[E]

[F]

[D]

A176D557.wmf

This copier uses a standard cross-mixing mechanism to keep the toner and developer evenly mixed. It also helps agitate the developer to prevent developer clumps from forming and helps create the triboelectric charge.

The developer on the turning development rollers [A] is split into two parts by the doctor blade [B]. The part that stays on the development rollers forms the magnetic brush and develops the latent image on the drum. The part that is trimmed off by the doctor blade goes to the backspill plate [C].

As the developer slides down the backspill plate to the agitator [D], the mixing vanes [E] move it slightly toward the rear of the unit. Part of the developer falls into the auger inlet and is transported to the front of the unit by the auger [F].

The agitator moves the developer slightly to the front as it turns, so the developer stays level in the development unit.

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15 July 1996 DEVELOPMENT

4.4 DEVELOPMENT BI AS

4.4.1 Overview

[A]

[B]

[C]

Detailed

Descriptions

A176D558.wmf

The high voltage control Board [A] applies the negative development bias to the lower sleeve roller through the receptacle [B] and the lower sleeve roller shaft [C]. Then the bias is applied to the upper sleeve roller through the rear sleeve roller holder made of conductive resin.

The development bias prevents toner from being attracted to the background area of the non-image area on the OPC drum where there is residual voltage. Also, the development bias is used to adjust image density according to the conditions the customer selected.

2-49

DEVELOPMENT 15 July 1996

4.4.2 Bias Control In Copy Cycle

The bias output is determined by five factors. The total bias is described as;

ADS Mode: V

= VBB + VBU + V

Manual ID Mode: VB = VBB + VBU + V

BMG BMG

+ V + V

BA BM

VB: Total bias

: Base bias

: ADS Compensation

: User Tool mode ID Selection Compensation

BMG

V V

1) Base Bias (V

: Magnification Compensation

: Manual ID Selection Compensation

)

Drum Potential

Dark

Original Density

Light

A176D559.wmf

As explained in the process control section, the base bias for development is determined by the residual voltage (V

) measured in process control data

initial setting.

= VR + (–220)

–300

Dark

)

1.02 V

ADS

(V)

2.3 Light

A176D560.wmf

2) ADS Compensation (V

V (negative)

According to the original background density, the bias is compensated. The compensation value is determined with the voltage measured by the ADS sensor (ADS sensor output: V

= 234 x (V

NOTE:

ADS

–2.3)

has a limited range from 0 V to –300 V.

ADS

) as follows:

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15 July 1996 DEVELOPMENT

3) Manual ID Selection Position Compensation (VBM)

According to the manual ID selection position, the bias is compensated as follows:

Exposure Lamp Voltage

V (negative)

LAMP LAMP

LAMP

LAMP LAMP LAMP

+4.5

+3.0

+0.5

→

–1.5 –3.5 –5.5

–90 –60

Lighter

Darker

56341

Detailed

Descriptions

Manual ID Position

A176D561.wmf

LAMP

: Exposure lamp voltage at ID level 4. This value is determined at

process control data initial setting.

4) User Tool Mode ID Selection Compensation (V

)

In the User Tool mode, the image density level can be selected from five steps. The V

is determined by the User Tool ID position setting as follows:

Lighter Darker

–90

V (negative)

–60

+60 +90

User Tool ID Position

A176D562.wmf

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DEVELOPMENT 15 July 1996

5) Magnification Compensation (V

BMG

Dev. Bias Voltage (negative)

is determined by the selected reproduction ratio as follows:

–100

–60

–40 –30 –20

81%

62%

50%

BMG

116%

115%80%61%

)

122%

123%

142%

141% 160%

A176D563.wmf

161%

4.4.3 Bias Control Out of Copy Cycle

To hold the toner on the sleeve rollers while the development sleeve rollers are rotating without image development, a constant –300 V bias is applied.

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15 July 1996 DEVELOPMENT

4.4.4 ID Sensor Pattern Bias

Potential

①

–700 V

①

Sensor Detection

②

ID Sensor

②

Bias Level

③

–300

IDB

= VP +300 (V)

4.0 V

ID Sensor

③

Output

A176D564.wmf

A172D565.wmf

While developing the ID sensor pattern, ID sensor bias is applied. ID sensor bias is determined during process control initial setting as follows:

Detailed

Descriptions

A charge is applied while grid voltage is –700 V to create the ID sensor pattern.

The drum potential (V The ID sensor bias (V

IDB

= VP – (–300)

= V

+ 300 (V)

) of the ID sensor pattern is checked.

IDB

) is adjusted so that it satisfies the following formula:

2-53

DEVELOPMENT 15 July 1996

4.5 TONER SUPPLY

4.5.1 Toner Supply Mechanism

[A]

[B]

[E]

[B]

[F]

[C]

[D]

[F]

A176D566.wmf

When the toner supply clutch [A] turns on, the agitator [B] moves the toner from front to rear and sends the toner to the toner supply roller.

The toner supply clutch [A] located inside the development motor [C] applies the rotation from the development motor to the toner supply roller gear [D], which drives the agitator gear [E]. Toner is caught in the grooves on the toner supply roller [F]. Then, as the grooves turn past the opening, the toner falls into the development unit.

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15 July 1996 DEVELOPMENT

4.5.2 Toner End Detection

Detailed

Descriptions

[A]

A176D567.wmf

The toner end sensor [A] detects if sufficient toner remains in the toner hopper or not. The toner end sensor monitors toner end condition once when the toner supply clutch turns on. When there is little toner inside the toner hopper and toner pressure on the toner end sensor becomes low, the toner end sensor outputs a pulse signal for each (one detection per one copy).

The toner near end indication is displayed on the LCD after receiving the pulse signal 150 times (If no pulse signal is output twice continually, the pulse count is canceled).

Fifty copies are allowed after entering toner near end condition. After fifty copies are made in toner near end condition, the machine enters the toner end condition and copying is prohibited.

When the main switch is turned off and on, or the front door is opened and closed, the machine drives toner supply mechanism and monitors the toner end sensor output. If the toner end sensor does not output the pulse signal twice continually, the toner end condition is canceled.

2-55

DEVELOPMENT 15 July 1996

4.5.3 Toner Supply Control

By using an SP mode ( SP Adjustment - PAGE 7), the following 3 of toner supply controls can be selected.

Auto Process Control Mode

•

Detect Mode

•

Fixed Mode

•

1) Auto Process Control Mode Originals have various image proportions and image densities. For the best toner supply control, it is necessary to link the amount of toner supplied on each copy cycle to the amount of toner consumed for each copy.

Fuzzy control

is used in this model to provide this kind of toner supply

control.

Fuzzy Control 1

According to data of the TD sensor, the CPU checks the following at every copy cycle:

1. The results of toner supply control (TD sensor output) in the previous copy cycle.

kinds

2. How quickly the toner density is changing. Then the CPU decides the most suitable toner supply amount (toner supply clutch on time) for the next copy cycle by using fuzzy logic.

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15 July 1996 DEVELOPMENT

Fuzzy Control 2

The image on the OPC drum changes due to variations in toner chargeability (influenced by the environment) even if toner concentration is constant. The ID sensor directly checks the image on the OPC drum and shifts

REF

the V

data under fuzzy control to keep the image on the OPC drum

constant.

NOTE:

The toner supply amount is changed at every copy cycle. The target toner density sensor output is updated under the following conditions:

1. During toner density sensor initial setting

2. During process control data initial setting

3. After the copy job is completed in case that 10 or more copies have been made since the last update.

(Refer to section 2.1.4 "Image Density Control" for details.)

2) Detect Mode In this mode, only the TD sensor is used to control the toner concentration (V

REF

data is fixed). The machine performs only fuzzy control 1. In ID sensor abnormal condition, the machine automatically enters this mode.

3) Fixed Mode In this mode, a fixed amount of toner is supplied every copy cycle as determined (4%, 7%, 11%, 14%) by SP mode ( SP Adjustment -

PAGE 7). There is no overtoning detection mechanism. In TD sensor abnormal condition or Drum Potential sensor abnormal condition, the machine automatically enter this mode.

Detailed

Descriptions

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DEVELOPMENT 15 July 1996

4.5.4 Bottle Drive Mechanism

[C]

[D]

[E]

[A]

[B]

A176D568.wmf

For easy access, the toner bottle is just inside the front cover. The bottle is positioned horizontally.

The bottle drive mechanism transports toner from the bottle to the toner hopper [A]. A worm gear [B] on the bottle drive motor drives this mechanism.

The toner bottle has a spiral groove [C] that helps move the toner to the toner hopper.

To prevent toner from scattering when the toner bottle is removed from the holder, toner shutter [D] which covers the hole [E] is installed on the toner bottle.

When the toner is set on the holder and the lever is lowered, the toner shutter [D] opens to supply toner to the toner hopper.

The bottle drive motor turns on 0.7 seconds when the toner end sensor turns on five times continually.

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15 July 1996 IMAGE TRANSFER

5. IMAGE TRANSFER

5.1 PRE-TRANSFER LAMP

Detailed

Descriptions

[A]

A176D569.wmf

The pre-transfer lamp [A] located in the drum unit is used to prevent incomplete toner transfer.

After the latent image is developed but before the image is transferred to the copy paper, the drum surface is illuminated by the pre-transfer lamp. This illumination reduces the negative potential on the drum surface charged by the main charge corona and partially discharged by the exposure. This makes image transfer easier.

The pre-transfer lamp is turned on and off by the charge power pack at the same time as when the main motor turns on and off.

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IMAGE TRANSFER 15 July 1996

5.2 IMAGE TRANSFER AND PAPER SEPARATION OVERVIEW

[A]

[B]

[F]

[E]

[C]

[D]

A176D570.wmf

This model uses a unique transfer belt unit instead of the transfer and separation corona unit. The transfer belt unit consists of the following parts:

[A] Transfer belt

A belt (length: 321 mm) with high electrical resistance which holds a high negative electrical potential and attracts the toner on the OPC drum onto the paper. Also the electrical potential attracts the paper itself and helps paper separation from the OPC drum.

[B] Transfer bias roller

Applies transfer voltage to the transfer belt.

[C] Transfer belt lift lever (driven by a solenoid)

Lifts the transfer belt to contact the transfer belt with the OPC drum.

[D] Transfer power pack

Generates the constant transfer current.

[E] Transfer belt cleaning blade

Removes toner attached on the transfer belt to prevent the rear side of the paper from being stained.

[F] Discharge plate

Discharges the remaining negative charge on the transfer belt and feeds it back to the transfer power pack to control the transfer current and keep it constant.

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15 July 1996 IMAGE TRANSFER

5.3 IMAGE TRANSFER AND PAPER SEPARATION

MECHANISM

The registration rollers [A] starts feeding the paper [B] to the gap between the OPC drum [C] and the transfer belt [D] in proper timing.

Immediately when the leading edge of the paper reaches the gap between the transfer belt and the OPC drum, the transfer belt lift lever [E] raises the transfer belt to contact the transfer belt and the OPC drum. The lift lever is driven by a solenoid.

[D]

[C]

[E]

[A]

Detailed

Descriptions

[B]

A176D571.wmf

Then a negative transfer bias is applied to the transfer bias roller [F] and attracts the positively charged toner [G] on the OPC drum. It also attracts the paper and separates the paper from the OPC drum.

A176D572.wmf

–800 V

[F]

[G]

A176D573.wmf

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IMAGE TRANSFER 15 July 1996

After the image transfer is completed, the charge on the transfer belt holds the paper to the transfer belt. After separating the paper from the transfer belt, the transfer belt is discharged by the discharge plate [A].

[A]

[B]

A176D574.wmf

The transfer power pack [B] inside the transfer belt unit

[B]

monitors the current fed back from the discharge plate to adjust the transfer current. This way, the current stays constant even if the paper, environmental conditions, and the transfer belt surface

[A]

resistance are changed.

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A176D575.img

15 July 1996 IMAGE TRANSFER

5.4 TRANSFER BELT UNIT LIFT MECHANISM

[C]

[E]

Detailed

Descriptions

[E]

[A]

[B]

[F]

[D]

A176D576.wmf

The transfer belt lift solenoid [A] located inside the transfer belt unit turns on to raise the transfer belt to contact the OPC drum at the appropriate timing. The front lever [B] and the rear lever [C] are connected to the solenoid by links [D] and push up the stays [E] when the solenoid turns on. The support spring [F] helps the solenoid to raise the transfer belt. The solenoid turns off after the copy job is finished. The transfer belt must be released from the OPC drum for the following reasons:

1. To prevent the ID sensor pattern on the OPC drum from being rubbed by the transfer belt because the transfer belt is located between the development unit and the ID sensor.

2. To decrease the load to the transfer belt cleaning blade, it is better to

keep toner on the non-image area (for example V

, VL, ID sensor pattern developed during process control data initial setting) from being transferred onto the transfer belt.

3. To prevent change of OPC drum characteristics by the influence of additives inside the rubber belt.

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IMAGE TRANSFER 15 July 1996

5.5 PAPER TRANSPORTATION AND BELT DRIVE

MECHANISM

[C]

[A]

[E]

[B]

[F]

A176D577.wmf

[F]

[D]

[E]

[D]

A176D578.wmf

The transfer belt is driven by the main drive motor [A] through belt and gears. Since the transfer belt electrically attracts the paper [B], the transport fan is not required.

The charge on the transfer belt is discharged by the discharge plate to reduce paper attraction and paper is separated by the paper stiffness above the transfer belt drive roller [C] where the transfer belt is turning.

The tapered parts [D] at both sides of the roller [E] help keep the transfer belt [F] at the center position.

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15 July 1996 IMAGE TRANSFER

5.6 TRANSFER BELT CLEANING MECHANISM

[D]

[A]

A176D579.wmf

[B]

A176D580.wmf

[C]

A176D581.wmf

Some toner may adhere to transfer belt when paper jams occur, or when the by-pass feed table side fences are set in the wrong position causing the erase lamp to miss some toner. The adhered toner must be removed to prevent the rear side of the copy paper from being stained. The cleaning blade [A] scrapes off any toner remaining on the transfer belt. A counter blade system is used for the transfer belt cleaning. The surface of the transfer belt is coated to make it smooth and so prevent the cleaning blade from being flipped by the transfer belt.

Detailed

Descriptions

The lever [B] on the front end of the cleaning blade releases the cleaning blade when the transfer belt unit is lowered and the lever is pushed by the transfer belt unit support prop. (The transfer belt unit is lowered when the lever [C] is turned anti-clockwise)

When the cleaning blade is released, the edge of the cleaning blade rubs the seal so that the seal [D] removes the toner or paper dust on the cleaning blade edge.

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IMAGE TRANSFER 15 July 1996

5.7 TONER COLLECTION MECHANISM

[B]

[A]

A176D582.wmf

Through idle gears [A], transfer belt drive is transmitted to the toner collection coil [B]. The toner collection coil transports the collected toner to the toner collection bottle. See section 2.2.5 for details.

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15 July 1996 PAPER FEED

6. PAPER FEED

6.1 OVERVIEW

[B]

[A]

[B]

[C]

A176D583.wmf

This model has three or four drawer tray paper feed stations. The following table shows the configuration of each feed stations of the copiers.

Feed station A175 copier A176/177 copiers A191/A192 copiers

1st

2nd

3rd 550 sheets tray 1500 sheets built-in L CT 550 sheets tray 4th 550 sheets tray — 550 sheets tray

550 sheets tra y 500 + 500 sheets

tandem feed tray

550 sheets uni versal tray 550 sheets universal

tray

500 + 500 sheets tandem feed tra y

550 sheets univ ersal tray

Detailed

Descriptions

Paper can also be fed using the by-pass feed table which has an independent feed mechanism. The by-pass feed table can hold 50 sheets of paper.

All feed stations use an FRR feed system. Rotation of the pick-up roller [A] drives the top sheets of paper from each tray to the feed [B] and the separation [C] rollers. The feed and separation rollers then take over paper drive. If more than one sheet is fed by the pick-up roller, the separation rollers rotates in the opposite direction and prevents all but the top sheet from passing through to the registration rollers.

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PAPER FEED 15 July 1996

6.2 FRR FEED SYSTEM

[B]

[A]

[C]

A184D584.img

This copier uses an FRR paper feed system using three rollers.

6.2.1 Pick-up Roller

The pick-up roller [A] is not in contact with the paper stack before it starts feeding paper. Shortly after the Start key is pressed, the pick-up roller drops down and feeds the top sheet between the feed [B] and the separation rollers [C]. At almost the same time that the paper’s leading edge arrives at the feed roller, the pick-up roller lifts off the paper stack so that it does not interfere with the operation of the feed and separation rollers. The feed and separation rollers then take over the paper feed process.

6.2.2 Feed and Separation Rollers

There is a one-way bearing inside the feed roller so it can turn only in one direction. The separation roller is driven in the opposite direction to the feed roller. The separation roller, however, is driven through a slip clutch (torque limiter clutch) which allows it to turn in either direction depending on the friction between the rollers. The separation roller solenoid keeps the separation roller in contact with the feed roller.

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15 July 1996 PAPER FEED

[B]

[A]

F3 F1

[B]

[A]

A76D585.img

The direction in which the separation roller [A] turns depends on the frictional forces acting on it. The slip clutch applies a constant clockwise force (F1). When there is a single sheet of paper being driven between the rollers, the force of friction between the feed roller [B] and the paper (F2) is greater than F1. So, the separation roller turns counterclockwise.

If two or more sheets are fed between the rollers, the forward force on the second sheet (F3), becomes less than F1 because the friction between the two sheets is small. So, the separation roller starts turning clockwise and drives the second sheet back to the tray.

Detailed

Descriptions

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PAPER FEED 15 July 1996

6.3 SLIP CLUTCH MECHANISM

A176D586.wmf

[A]

[G]

[D]

[B]

[E]

[F]

[C]

A176D587.img

The slip clutch [A] consists of the input hub [B] and the output hub [C] which is the case of the clutch as well. The magnetic ring [D] and the steel spacers [E] are fitted onto the input hub. The ferrite ring [F] is fitted into the output hub. Ferrite powder [G] packed between the magnetic ring and the ferrite ring [F] generates a constant torque due to magnetic force. The input hub and the output hub slip when the rotational force exceeds the constant torque.

This type of slip clutch does not require lubrication.

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15 July 1996 PAPER FEED

6.4 FRR FEED DRIVE MECHANISM

[D]

[K]

[C]

[L]

[J]

Detailed

Descriptions

[B]

[A]

A176D588.wmf

[D]

[G]

[F]

[B]

[E]

[H]

[I]

A176D589.wmf

The rotation of the paper feed motor [A] is transmitted to the gear [B] via the timing belt [C], and then transmitted to the separation roller via the feed clutch gear [D], gear [E], gear [F] and gear [G].

If the paper feed station is not selected, the separation roller solenoid [H] de-activates and the separation roller [I] rotates freely in the reverse direction of paper feeding.

Gear [B] also transmits the drive to the vertical transport roller [J] via gear [D], idle gear [K] and gear [L].

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PAPER FEED 15 July 1996

[A]

[F]

[D]

[B]

[C]

[E]

[G]

A176D589-2.wmf

[I]

[H]

A176D590.wmf

When the paper feed station is selected and the start key is pressed, the feed clutch [A], separation roller solenoid [B], and the pick-up solenoid [C] turn on at once.

When the feed clutch [A] activates to rotate the feed roller [D], the feed roller and the pick-up roller [E] turn together because they are linked by the idle gear [F].

When the separation roller solenoid [B] turns on, the separation roller [G] contacts the feed roller [D] then rotates together with the feed roller in spite of the separation roller’s drive in the opposite direction due to the torque limiter function in the separation roller [G].

When the pick-up solenoid [C] activates, the pick-up roller [E] lowers to make contact with the top sheet of the paper stack and send it to the feed and separation rollers. When the paper feed sensor [H] detects the leading edge of the paper [I], the pick-up solenoid de-energizes to lift the pick-up roller and the paper feed clutch de-energizes at a certain time to wait until it is ready to feed to the registration roller.

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Ricoh FT7650, FT660 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

IMPORTANT SAFETY NOTICES