Ricoh FT 6645 Diagram

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Page 1

FT6645/6655/6665

SERVICE TRAINING

MANUAL

Page 2

SECTION 1

OVERALL MACHINE

INFORMATION

Page 3

1. SPECIFICATION

Configuration: Console Copy Process: Dry electrostatic transf er 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 A5/51/2" x 81/2" (Tray)

B5/81/2" x 11" (1.5K LCT) A6/51/2" x 81/2" (By-pass)

Duplex Copying: Maximum A3/11" x 17"

Minimum A5/51/2" x 81/2" (sideways)

Copy Paper Weight: Paper tray: 52 ~ 128 g/m2, 14 ~ 34 lb

Bypass feed table: 52 ~ 157 g/m2, 14 ~ 42 lb Duplex copying: 64 ~ 104 g/m2, 17 ~ 24 lb

Reproduction Ratios: 4 Enlargement and 6 Reduction

A4/A3 Version LT/LDG Version

Enlargement 200%

141% 122% 115%

Full Size 100% 100%

Reduction 93%

82% 75% 71% 65% 50%

200% 155% 129% 121%

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

STM 1-1 FT6645/6655/6665

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Rev. 7/94

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

220 ∼ 240V, 50Hz/60Hz, more than 10A ( for EU and AA)

Power Consumptio n: FT6645(A095) and FT 6655 (A096) copiers

Copier only Full system* Warm-up 0.90 kVA 0.90 kVA Stand-by 0.25 kVA 0.25 kVA

Copying 1.20 kVA 1.30 kVA

Maximum 1.45 kVA 1.50 kVA

FT6665 (A097) copier

Copier only Full system*

120 V

machine Warm-up 1.20 kVA 1.20 kVA 1.25 kVA 1.25 kVA Stand-by 0.25 kVA 0.22 kVA 0.25 kVA 0.24 kVA

Copying 1.80 kVA 1.70 kVA 1.80 kVA 1.75 kVA

Maximum 1.80 kVA 1.70 kVA 1.80 kVA 1.75 kVA

230 V

machine

120 V

machine

230 V

machine

*Full System:

• Mainframe with dual job feeder, compact

sorter stapler and 3,50 0-sheet large capacity tray

• Mainframe with dual job feeder, floor type

sorter stapler and 3,50 0-sheet large capacity tray

• Mainfra me with recir culatin g document

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

FT6645/6655/6665 1-2 STM

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Noise Emission:

Rev. 7/94

Sound Pressure Leve l: The meas ure ments are made according to ISO7779

Copying (FT6645/6655 copiers) 55 dB (A) 62 dB (A) Copying (FT6665 copier) 60 dB (A) 64 dB (A)

Copier only Full system*

Full System:

• Mainframe with dual job feeder, compact

sorter stapler and 3,50 0-sheet large capacity tray

• Mainframe with dual job feeder, floor type

sorter stapler and 3,50 0-sheet large capacity tray

• Mainfra me with recir culatin g document

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

Dimensions: 690 x 690 x 980 (W x D x H Mainframe only)

1280 x 690 x 1020 (W x D x H Mainframe with copy tray, platen cover)

Weight: Copier only: (Without the optional platen cover

= Approximately 2 kg) FT6645 (A095) copier: Approximately (333 lbs) FT6655 (A096) copier: Approximately (360 lbs) FT6665 (A097) copier: Approximately (360 lbs)

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

A4/LT (sideways) A3/DLT B4/LG FT6645 copier 45 23 27 FT6655 copier 55 28 35 FT6665 copier 65 33 41

Warm-up Time: Less than 5 minutes (20°C) First Copy Time:

(A4/81/2" x 11" sideways

3.1 seconds FT6645/6 655 (A095 /A096 copier s)

2.7 seconds FT6665 (A097 copier)

from the 1st feed station) Copy Number Input: Number keys, 1 to 999 (count up or count down) Manual Image Density 7 steps

Selection:

STM 1-3 FT6645/6655/6665

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Rev. 7/94

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

second to 999 seconds or no auto reset.

Copy Paper Capacity: • By-pass feed table: approximately 50 sheets

• Paper tray: approximately 550 sheets

• Tandem tray: approximately 500 sheets/side,

1000 total

• Large capacity tray: approximately 1,500

sheets

• Duplex: 50 sheets

Toner Replenishment: Black Only: Cartridge exchan ge

1,100 g/cartridge, Yield 38,000 copies (6% originals)

Developer Replenishment:

Black Only: 1Kg/Bag, 120,000 copies (6% originals)

Optional Equipment: • Type 610, Platen cover

• DF60, Dual job feeder

• DH400, Recirculating document handler

• ST25, 20 bin sorter stapler (Floor type)

• ST24, 20 bin compact sorter stapler

• SR400, Finisher

• RT31, 3,500-sheet Large capacity tray

• Type B, Receiving Tray

Toner Collection

7,500cc, 120,000 copies (6% origin als)

Bottle Capacity:

FT6645/6655/6665 1-4 STM

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2. MACHINE CONFIGURATION

2.1 COPIER OVERVIEW

There are two types of mainframe.

FT6645 (A095) copier

Rev. 7/94

550 550

550

FT6655 (A096) FT6665 (A097) copiers

500 x 2 or 500 550

1,500

(3,500)

Three 550-shee t paper trays Optiona l 3,500-sheet larg e capacity t ray

Tandem pape r 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

STM 1-5 FT6645/6655/6665

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Rev. 7/94

2.2 SYSTEM OVERVIEW

System A

The mainframe FT6645 (A095) with dual job feeder and compact sorter stapler.

Compact sorter stapler ST24 (A374)

Dual job feeder DF60 (A376)

3,500-sheet s large capacity tray RT31 (A38 0)

System B

Mainframe type FT6645/6655/66 65( A0 95/A09 6/A097) with dual job feeder and floor type sorter stapler. The mainframe in the illustration below is the FT6655 (A096).

Floor type sorter stapler ST25 (A377)

Dual job feeder DF60 (A376)

3,500-sheets large capacity tray RT31(A380)

FT6645/6655/6665 1-6 STM

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System C

The mainframe FT6665/6665 (A096/A097) with recirculating document handler and finisher.

Recirculating document handler DH400 (A378)

Finisher SR400 (A379)

Rev. 10/94

3,500-sheets large capacity tray RT31 (A38 0)

NOTE: All references to (A096 copier only) now refers to (A096 and

A097 copiers).

STM 1-7 FT6645/6655/6665

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3. COPY PROCESS AROUND THE DRUM

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 propor tional 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 prod ucing an electr ical lat ent imag e on the drum surface.

The amount of charge remaining as a latent image on the drum depends on the exposure lamp intensity contr olled 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 area s dissipa tes.

FT6645/6655/6665 1-8 STM

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5. DRUM POTENTIAL SENSOR

The drum potential sensor detects the electr ical poten tial o n the drum to compensate image pro cessing elements.

6. DEVELOPMENT Positively charged toner is attracted to the negatively charged areas of the drum, thus developing the laten t image. (The positive triboele ctric char ge of the toner is caused by friction between the carrier and toner particles.)

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

1) The "breakaway" level at which toner is attracted to the drum and at which toner remains on the developm ent rollers.

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 fro m the exposed areas of the drum. This makes imag e transf er 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 particle s from the dru m surface onto the copy paper. At the same time, the copy paper is electrica lly attracted to the transfer belt.

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 neut ralizes the charge potential of the drum surface.

STM 1-9 FT6645/6655/6665

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4. MECHANICAL COMPONENT LAYOUT

14 15 16

19 20

22 23

FT6645/6655/6665 1-10 STM

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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

21. Separation Roller, Bypass

22. Registration Rollers

23. Transfer Belt

24. Vertical Transport Roller s

25. Tandem Tray (A096 copier) 550-sheet Tray (A095 copier)

26. Universal Tray

27. 1500-sheet LCT (A096 copier) 550-sheet Tray (A095 copier)

28. Toner Collection Bottle

29. Transfer Belt Cleaning Blade

30. Hot Roller

31. Pressure Roller

32. Jogger Fences

14. Erase Unit

15. Drum Potential Sensor

16. Toner Hopper

17. Development Unit

18. Pre-Transfer Lamp

19. Pick-up Roller, Bypass

20. Feed Roller, Bypass

33. Duplex Positioning Roller

34. Duplex Pick-up Roller

35. Duplex Feed Roller

36. Separation Belt

37. Junction Gate

38. Exit Rollers

39. Optics Cooling Fan

STM 1-11 FT6645/6655/6665

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5. DRIVE LAYOUT

❶

❽

❼

❻

❺

❾

❷

❸

❹

❶ Main Motor ❷ Scanner Drive Motor ❸ Fusing/Duplex Drive Motor ❹ Paper Feed Motor ❺ Toner Collection Motor ❻ Registration Clutch ❼ By-Pass Feed Motor ❽ BY-Pass Feed Clutch ❾ Development Drive Motor

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

FT6645/6655/6665 1-12 STM

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6. PAPER PATH

6.1 STANDARD COPYING

[E]

[F]

[D]

[C]

[B]

[A]

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 depen ds on which mode the opera tor has selected. For copy processing, all sheets follow the same path s from the paper feed mechanism [A] thro ugh the reg istra tion 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 furth er processing.

STM 1-13 FT6645/6655/6665

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6.2 MULTIPLE 2-SIDED COPYING

a. Front Side

[B]

[A]

[D]

[C]

b. Rear Side

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 throug h the duplex feed mechanism and vertical tra nspor t rollers [C] to the registration rolle rs [D]. After that, these sheets follow the same path as standard copying from the registration rollers to the sorter.

FT6645/6655/6665 1-14 STM

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7. ELECTRICAL COMPONENT DESCRIPTION

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

NOTE: For RT31 description s, see Section 7, page 3

Symbol Name Function Index

No.

Motors

M 1 Scanner Drive Drives the 1st and 2nd scanners

(dc servo).

M 2 Exhaust Fan Rem oves the heat from around

the fusing unit. M 3 Main Drives the main unit components. 44 M 4 Development Drive Drives the development unit. 45 M 5 By-pass Feed Drives the by-pass feed rollers. 46 M 6 3rd Scanner Drive Drives the 3rd scanner (dc

stepper) M 7 Toner Bottle Drive Rotates the toner bottle to supply

toner to the toner hopper. M 8 Charge Wire Cleaner

Drive

M 9 Jogger Drives the jogger fences to

M10 Lens Horizontal Drive Shifts the lens horizontal position. 51 M11 Lens Vertical Drive Shifts the lens vertica l position. 52

Drives the main charge wire

cleaner to clean the charge wire.

square the paper stack in the

duplex tray (dc stepper).

M12 Optic Cooling Fan Removes heat from the optics

unit. M13 Fusing/Duplex Drive Drives the fusing unit, the duplex

unit, and the paper exit rollers. M14 Paper Feed Drives all feed and transport

rollers in the paper tray unit. M15 1st Lift Raises the bottom plate in the 1st

paper tray. M16 2nd Lift Raises the bottom plate in the

2nd paper tray. M17 Toner Collection Transports the collected toner to

the toner collection bottle.

STM 1-15 FT6645/6655/6665

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Rev. 7/94

Symbol Name Function Index

No.

M18 3rd Lift

(A095)

M19 Side Fence Drive

(A096/A097)

Raises the bottom plate in the 3rd

paper tray.

Opens and closes the front and

the rear side fences of the

tandem tray. M20 Rear Fence Drive

(A096/A097)

Moves the papers stacked in the

left tandem tray to the right

tandem tray. M21 LCT Motor

(A096/A097)

Lifts and lowers the LCT bottom

plate to bring paper to the feed

position and allow loading of the

paper.

Magnetic Clutches

MC1 Toner Supply Turns the toner supply roller to

supply toner to the development

unit.

MC2 Registration Drives the registration rollers. 58

127

MC3 By-pass Feed Starts paper feed from the

by-pass feed table.

MC4 Duplex Transport Drives the duplex transport rollers

to transport the paper to the

vertical transport rollers.

MC5 Duplex Feed Starts paper feed from the duplex

tray to the duplex transport rollers.

MC6 1st Feed Starts paper feed from the 1st

feed tray.

MC7 2nd Feed Starts paper feed from the 2nd

feed tray.

MC8 3rd Feed Starts paper feed from the 3rd

feed tray.

101

104

FT6645/6655/6665 1-16 STM

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Rev. 7/94

Symbol Name Function Index

No.

Switches

SW1 By-pass Table Detects if the by-pass feed table

is open or closed.

SW2 Front Door Safety Cuts the DC power line and

29 detects if the front door is open or not.

SW3 1st Tray Set

Detects if the 1st tray is set or not. 66

(A095)

SW4 2nd Paper Size Determines what size paper is in

67 the 2nd (universal) paper tray.

SW5 Toner Overflow Detects when the toner collection

75 bottle is full.

SW6 Toner Collection

Bottle Set

SW7 Lower Front Door

Safety

SW8 3rd Tray Set

Detects if the toner collection

77 bottle is set or not.

Detects if the front door is open

83 or not.

Detects if the 3rd tray is set or not. 84

(A095)

SW9 Main Provides power to the copier 122

SW10 Tray Down

Lowers the LCT bottom plate. 126

(A096/A097)

Solenoids

SOL 1 Junction Gate Moves the junction gate to direct

copies to the duplex tray or to the paper exit.

SOL 2 Duplex Positioning Controls the up- down move men t

of the positioning roller.

SOL 3 By-pass Pick-up Controls the up-down movemen t

of the pick-up roller for by-pass feed.

SOL 4 Guide Plate Opens the guide plate when a

paper misfeed occurs aro und this area.

SOL 5 Transfer Belt

Positioning

Controls the up-down move ment of the transfer belt unit.

STM 1-17 FT6645/6655/6665

Page 20

Symbol Name Function Index

No.

SOL 6 Pressure Arm Presses the paper on the duplex

tray against the duplex feed rollers.

SOL 7 Tandem Lock Locks the left tandem feed tray

and separates the right and left tandem trays.

SOL 8 1st Pick-up Controls the up-down move ment

of the pick-up roller in the 1st feed station.

SOL 9 1st Separation Roller Controls the up-down movement

of the separation roller in the 1st feed station.

SOL10 2nd Pick-up Controls the up-down movement

of the pick-up roller in the 2nd feed station.

SOL11 2nd Separation Roller Controls the up-down movemen t

of the separation roller in the 2nd feed station.

SOL12 3rd Pick-up Controls the up-down move ment

of the pick-up roller in the 3rd feed station.

100

102

103

105

SOL13 3rd Separation Roller Controls the up-down move ment

of the separation roller in the 3rd feed station.

Sensors

S 1 Scanner HP Informs the CPU when the 1st

and 2nd scanners are at the home position.

S 2 Platen Cover

Position–1

Informs the CPU that the platen cover is in the up or down position (related to APS/ARE function).

S 3 Platen Cover

Position–2

Informs the CPU that the platen cover is in the up or down position to detect if the original has been removed or not.

106

FT6645/6655/6665 1-18 STM

Page 21

Rev. 12/93

Symbol Name Function Index

No.

S 4 Lens Vertical HP Informs the CPU that the lens is

at the full-size position.

S 5 Lens Horizontal HP Informs the CPU that the lens is

at the horizontal home position .

S 6 3rd Scanner HP Informs the CPU when the 3rd

scanner is at the home position.

S 7 By-Pass Paper End Informs the CPU that there is no

paper in the by-pass feed table.

S 8 Guide Plate Position Informs the CPU if the

registration guide plate is closed or not.

S 9 Jogger HP Detects if the duplex jogger

fences are at the home position or not.

S10 Vertical Transport Detects the leading edge of the

paper to determine the paper feed timing of the next sheet.

S11 Duplex Exit Dete cts the leading edge of the

paper to determine the duplex transport clutch on timing .

S12 Duplex Entrance

Sensor

Detects the leading edge of the paper to determine the duplex

14 feed clutch off timing.

S13 Duplex Paper End Detects paper in the duplex tray. 13 S14 Duplex Transport Detects the leading edge of the

12 paper to control the jogger motor and the positioning solenoid on timing.

S15 Exit Detects misfeeds. 15 S16 Fusing Exit Detects misfeeds. 16 S17 Paper Guide Detects misfeeds. 17 S18 Auto Image Density Senses the background density

20 of the original.

S19 Original Length–2 Detects original length. 21 S20 Original Length–1 Detects original length. 22 S21 Original Width Detects original width. 23

STM 1-19 FT6645/6655/6665

Page 22

Symbol Name Function Index

No.

S22 By-Pass Paper Size Informs the CPU what size paper

26 is in the by-pass feed table.

S23 Toner Density Senses the amount of toner in

27 the black developer.

S24 Registration Detects misfeeds and controls

28 registration clutch off-on timing.

S25 Toner End Detects toner end condition. 30 S26 Auto-Respon se Returns the display from the

34 screen saver.

S27 Drum Potential Detects the drum surface

39 potential.

S28 Image Density Detects the density of the ID

41 sensor pattern on the drum.

S29 1st Paper End Informs the CPU when the 1st

68 cassette runs out of paper.

S30 1st Paper Near End Informs the CPU when the 1st

69 cassette is in near end condition.

S31 1st Paper Feed Controls the 1st paper feed clutch

70 off/on timing and the 1st pick-up solenoid off timing.

S32 2nd Paper Near End Informs the CPU when the 2nd

cassette is in near end condition.

S33 1st Lift Detects the correct feed height of

the 1st cassette.

S34 2nd Paper End Informs the CPU when the 2nd

cassette runs out of paper.

S35 Toner Collection

Motor

Detects the toner collection motor operation.

S36 2nd Lift Detects the correct feed height of

the 2nd cassette.

S37 3rd Lift Detects the correct feed height of

the 3rd cassette.

S38 3rd Paper Near End

(A095 copier only)

Informs the CPU when the 3rd cassette is in near end condition.

S39 3rd Paper End Informs the CPU when the 3rd

cassette runs out of paper.

FT6645/6655/6665 1-20 STM

Page 23

Rev. 7/94

Symbol Name Function Index

No.

S40 3rd Paper Feed Cont rols the 3rd paper feed

clutch off/on timing and the 3rd pick-up solenoid off timing.

S41 2nd Paper Feed Controls the 2nd paper feed

clutch off/on timing and the 2nd pick-up solenoid off timing.

S42 Base Plate Down

(A096/A097)

Detects when the bottom plate is completely lowered to stop the 1st lift motor.

S43 Side Fence

Positioning

Informs the CPU when the tandem tray side fences are open.

(A096/A097)

S44 Rear Fence Return

(A096/A097)

Informs the CPU when the tandem tray rear fence is in the return position.

S45 Rear Fence HP

(A096/A097)

Informs the CPU when the tandem tray rear fence is in the home position.

S46 Left Tandem Paper

End

Informs the CPU when the left tandem tray runs out of paper.

(A096/A097)

S47 LCT Near End

(A096/A097)

S48 Tray Down

(A096/A097)

Detects the paper near end condition.

Detects when the tray is completely lowered to stop the LCT motor.

S49 Tray Paper Set

(A096/A097)

Informs the CPU when the paper is set on the LCT bottom tray.

PCBs

PCB 1 AC Drive Provides AC power to the

exposure lamp and fusing lamp.

PCB 2 Main Controls all machine functions. 109 PCB 3 Optic Control Controls all optics components. 110 PCB 4 High Voltage Control Controls the output of both power

packs and development bias.

123

124

125

108

111

STM 1-21 FT6645/6655/6665

Page 24

Rev. 7/94

Symbol Name Function Index

No.

PCB 5 Paper Feed Control Controls all components in the

paper bank.

PCB 6 DC Power Supply

Provides DC power. 113

Unit PCB 7 Guidance Controls the guidance display. 120 PCB 8 Operation Panel Controls the LED matrix, and

monitors the key matrix.

Lamps

L1 Exposure Applies high intensity light to the

original for exposure . L2 Fusing (2 in A097) Provides heat to the hot roller. 32 L3 Quenching Neutralizes any charge remaining

on the drum surface after

cleaning. L4 Erase Discharges the drum outside the

image area. L5 Pre-transfer Reduces the charge on the drum

surface before tra nsfer.

112

121

Power Packs

PP1 Transfer Provides high voltage for the

transfer belt and controls the

transfer belt positioning solenoid.

PP2 Charge Provides high voltage for the

charge corona wires, and the grid

plate. Controls QL, PTL, and

charge wire cleaner moto r

functions.

Others

TS1 Optics Thermoswitch Opens the exposure lamp circuit

if the optics unit overheats.

TF1 Fusing Thermofuse Opens the fusing lamp circuit if

the fusing unit overheats.

117

119

FT6645/6655/6665 1-22 STM

Page 25

Rev. 10/94

Symbol Name Function Index

No.

TH1 Fusing Thermistor Senses the temperatur e of the

hot roller.

TH2 Optics Thermistor Monitors the temperature of the

optics cavity.

TH3 Drum Thermistor

(Located on the ID

Monitors the temperature of the

OPC drum.

Sensor Ass’y)

H1 Transfer

Anti-Condensation

Turns on when the main switch is

off to prevent moisture from

forming on the transfer belt.

H2 Optics

Anti-Condensation

Turns on when the main switch is

off to prevent moisture from

forming on the optics.

RA1 Main Power Relay Controls main power. 107

CO1 Total Counter Keeps track of the total number

114

of copies made.

NF1 Noise Filter Removes electrical noise. 115 CB1 Circuit Breaker Provides back-up high current

116 protection for the electr ical components.

LA1 Lightening Arrestor Removes current surges from the

118 AC input lines.

FT6665 (A097) copier only (unique items)

Symbol Name Function Index

No.

Motors

M22 AC Drive Cooling

Fan

Removes heat from around the AC drive unit.

141

M23 Optic Cooling Fan-2 Removes heat from the optic unit. 142 M24 Duplex Cooling Fan Cools the paper on the duplex

143

tray to reduce the heat around the drum.

STM 1-23 FT6645/6655/6665

Page 26

Rev. 12/93

8. AC AND DC POWER DISTRIBUTION

The above illustration shows how ac power (120V/220V~240V) from the wall outlet is supplied to each component. When the copier is plugged in and the main switch is turned off, ac power is supplied to the anti-condensation heaters. When the main switch is turned on, the ac power supply to the anti-condensatio n heater s is cut off and ac power is supplied to the ac drive board. The ac drive board supplies power to the exposure and fusing lamps without voltag e step down.

The ac power is also supplied to the dc power supply board via main switch. The dc power supply board converts the wall outlet ac power into +38, +24, +12, +5, -12 volt dc.

These dc voltage are supplied to each component via the main control board, paper feed control board, and high voltage control board.

The dc voltages for all the peripherals are supplie d th rou gh the main contr ol board.

FT6645/6655/6665 1-24 STM

Page 27

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STM 1-25 FT6645/6655/6665

Page 28

Rev. 7/94

9. FT6665 (A097) COPIER UNIQUE POINTS

The following are the FT6665 (A097) copier’s main unique points compared with the other machines in the same series FT6645/6655 (A095, A096) copiers.

The copy speed of FT6665 copier is 65 CPM. To achieve this high copy speed, the paper transport and copy process speed were increased from 330 mm/sec FT6645/6655 copier to 430 mm/sec.

The paper tray and periphe ral config ura tion of the FT6 665 copier is exactly the same as the FT6655 copier.

FT6645/6655/6665 1-26 STM

Page 29

Item Unit Description Reason

Rev. 7/94

Drive Motor Main Motor Due to higher paper transport and copy

1 2 3 4 5

Exterior Right Door Printed model name is different

Optics Exposure Lamp Exposure lamp wattage is changed. Refer

Paper Feed Separation Roller torque

8 9

Duplex Brush Roller Due to higher paper transport speed, roller

Fusing Pressure Springs Due to higher copy speed, the spring

Fans AC Drive Cooling Fan Due to higher lamp power, motor speed,

16 17

Fusing/Duplex Drive Motor

Development Drive Motor

Optics Fan Filter To keep the optics cool in spite of a longer

Optics Control Board ROM on the optics control board is

limiter

Positioning Roller Arm Due to higher copy speed, the arm is

Duplex Paper End Sensor Due to higher copy speed, the pressure

Fusing Lamp Due to higher copy speed, lamp wattage

Pressure Roller

Cleaning Roller

Oil Supply Roller Cleaning

Roller (not illustrated)

Optic Cooling Fan-2 Duplex Cooling Fan

process speed

to STM page 2-31.

exposure lamp on time, a thinner filter is used.

different due to higher scanner motor speed.

Due to higher paper feed speed, torque limit is increased.

diameter is decreased (A095/A096 copier: 40mm, A097 copier: 25mm).

moved more frequently. Therefore, lighter arm is used.

arm moves more frequently. To ensur e the paper end detection, the detection mechanism on the pressure arm is replaced with reflective photo sensor.

tension is increased to maintain sufficient fusing ability.

is increased. (120V machine has two fusing lamps.)

Due to higher copy speed, higher cleaning ability is required. So, the contact pressure between the pressure roller and the cleaning roller was increased. To facilitate servicing, the cleaning roller can be replaced. (Cleaning roller unit is replaced for A095/A096 copiers.)

Due to the higher fusing roller rotation speed, the oil supply roller tends to collect foreign material. Thus, a cleaning roller has been added.

etc. the machine generates more heat. Therefore, three new fans are added.

STM 1-27 FT6645/6655/6665

Page 30

Rev. 10/94

Item Unit Description Reason

19 20

Others DC Power Supply Unit

(120V machine only)

DC Harness Connectors for new fans are added.

Paper Guides To ensure the correct paper trans port, the

AC Drive Board Since one fusing lamp was added, the AC

Since fans are added and motor speed is increased, the DC power supply unit is improved.

guides are added.

Drive Board was modified. (120V machine only)

FT6645/6655/6665 1-28 STM

Page 31

SECTION 2

DETAILED SECTION

DESCRIPTIONS

Page 32

1. PROCESS CONTROL

VL Pattern

Toner Supply Control

(Fuzzy Control)

1.1 OVERVIEW

Original Scale

Image Density Control (Fuzzy Control)

Latent Image Control

Latent image Control

Exposure Control

Charge Control

Temperature Sensor

Paper

D Pattern

Lamp Voltage

Grid Voltage

ID Sensor

VL Pattern

ADS Pattern

VD Pattern

Erase Lamp

Drum Potential Sensor

Original

Toner Supply On time

Development. Bias

TD Sensor

Image Density Control

Exposure Glass

Main PCB

This model uses two process control methods. One compensates for variation in the drum potentia l (latent ima ge contr ol) and the othe r controls the toner concentration and toner supply amount (image density control).

STM 2-1 FT6645/6655/6665

Page 33

1.1.1 Latent Image Control

Erase Drum

QL Charge

Exposure

Black White

Potential Sensor

The figure shows the changes of the drum potential during the copy process. Vo: The drum potential just after chargin g the drum . VD (Dark Potential): The drum potential just after exposing the black

pattern (VD pattern)

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

pattern (VL pattern)

VR (Residual Voltage): The drum potential just after exposur e by the

erase lamp.

After long usage following installation or a PM, drum pote ntial will gradua lly increase due to the following factors:

Dirty optics or exposure lamp deterioration Dirty charge corona wire, grid plate and corona casing. 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 developme nt bias voltage.

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

FT6645/6655/6665 2-2 STM

Page 34

1.1.2 Image Density Control

Rev. 12/93

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 concent rat ion in the developer at a constant level. However, the imag e on the OPC drum varies due to the variation of toner chargeability (influenced by the environment, humidity) even if the toner concentration is constant. The ID sensor compensation causes toner concentration to change 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 Toner supply level data (VREF) of the TD sensor

STM 2-3 FT6645/6655/6665

Page 35

Rev. 4/15/94

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 or Timer On (Fusing Tem p. < 100°C)

Charge wire cleaning (if mor e than 5 K copies are made since last cleaning

Drum Potential Sensor Calibration

①

Drum Conditioning Start (F using Temp. = 180°C)

VSG Adjustment

VR Measurement

VD/VL/VR Correction

TD Sensor Detection

②

ID Sensor Detection/Correction

③

ADS Adjustment

① : See Latent Image Control section (P age 2-5) for details. ② : See Image Density Contr ol section (Page 2-1 2) for details. ③: See Optics section (Page 2-39) for details.

FT6645/6655/6665 2-4 STM

Page 36

1.3 LATENT IMAGE CONTROL

Case

Sensor

1.3.1 Drum Potential Sensor Calibration

Rev. 4/15/94

Output

[A]

Drum

Amp.

[B]

High Voltage Control Board

Main PCB

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 depend s 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 (hot rolle r temp era ture is less than 100°C at main switch/timer turn on).

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

By measuring the output of the drum poten tial 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 .) To prevent toner attraction during potential sensor calibration an equivelent bias voltage (-100V and -800V) is applied to the development roller s.

STM 2-5 FT6645/6655/6665

Page 37

Rev. 4/15/94

Light

1.3.2 Drum Conditioning

When the fusing temperatu re 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 (VR ) are stabilized, as in continuous copy runs.

1.3.3 VSG Adjustment

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

1.3.4 VR Measurement

New Drum Used Drum

Drum Potential

Dark

Original Density

The solid line in the figure above shows the relationship between the drum potential and the original density. To get constant copy quality thr oughout the drum’s life, this relationship must be maintained.

Since this relationship tends to change to the one represented by the dotted line, compensations are req uired. Factors causing this change are changes in the optics section, in the charge section and in drum sensitivity.

The residual voltage (VR) cannot be co mpe nsate d even if the exposure lamp voltage is increased. Therefore, the VR change has to be compensated by other means.

After the drum conditioning the main control board turns on the erase lamps. Then the dru m potential is checked by the potential sensor. This measured drum potential is in fact VR. This VR is used as the standard for the VD and VL corrections.

NOTE: In the figure above, the residual voltage (VR ) for the new drum is

0V. Actually, there is some residual voltage even on the new drum.

FT6645/6655/6665 2-6 STM

Page 38

1.3.5 VD Correction

[-V]

VD Exposure Glass

VD Pattern

Drum Potential

VD Compensated

–770

After many copies

New Drum

Dark

Original Density

Light

The drum potential, just after the black patter n (VD 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 VD, the first scanner moves to the home position and the VD pattern (Black) located on the bottom side of the exposure glass bracket is exposed on the drum.

The main control board measures VD through the drum potential sensor and adjusts it to a target value by adjusting the grid bias voltage (V GRI D ).

On the other hand, there is a change of the drum residua l voltage (VR), so that the target VD voltage is compensated as follows:

Target VD Value: VD = VR + (–770)

The adjusted grid bias voltage (VGRID) is kept in memory until the next process control data initial setting.

STM 2-7 FT6645/6655/6665

Page 39

1.3.6 VL Correction

[-V]

Exposure Glass

VL Pattern

Drum Potential

–770

Dark LightOriginal Density

Dirty optics and/or exposure lamp deterio ration decreases the intensit y of the light that reaches the drum. In additio n to this, the drum sensitivit y also changes during the drum’s life. These factors change the drum potential just after white pattern exposu re (V L : Light Potential).

–140

Only VD Compensated

VD and VL

Compensated

New Drum

To check the actual VL, the first scanner moves under the VL pattern (White) located underneath the original scale. The pattern is exposed on the drum.

The main control board measures VL through the drum potential sensor and adjusts it to a target value by adjusting the exposure lamp voltage (VLAMP).

The residual voltage (VR) change also affects VL, so that VL’s target voltage is compensated as follows:

Target VL Value: VL = VR + (–140) The adjusted exposure lamp voltage (VLAMP) is stored in memo ry until the

next process control data initial setting.

FT6645/6655/6665 2-8 STM

Page 40

1.3.7 VR Correction

New Drum

Light

[-V]

Drum

VD and VL Compensated

Potential

–770

Development Bia s (VBB)

–140

Dark

Original Density

Potentials (VR, VD, VL) are monitored by the drum potentia l sensor. (T his is done only when the fusing temperatu re is less than 100°C when the machine is turned on.) During the check cycle, the VD and VL patterns are exposed and the drum potential on the areas of each pattern is checked by the potential sensor.

Compare the curve of the VD and VL compensated drum potential with the curve of the new drum. They are parallel but the compensat ed poten tial is still higher (VR) than the new drum potential. To prevent dirty backgrounds due to increased residual poten tial, develo pment bias (VBB) is applied as follows:

VBB= VR + (–220)

The adjusted development bias (VBB) is stored in memory until the next process control initial setting.

STM 2-9 FT6645/6655/6665

Page 41

New VL

Rev. 4/15/94

1.3.8 Initial Setting Sequence

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

Scanner Motor

Exposure Lamp

Potential Sensor Output

forward reverse

V800

V100

1. Potential sensor calibration

VD New VD

New VR

2. VR’, VD’, VL’ potential detection

Latent Image Control

3. VD, VL correction

for the purpose of ADS sensor correction

4. ID sensor pattern potential detection

1. Potential sensor calibr ation (Fusing Temp < 100° C) By measuring the output of the drum potential sensor when –100 V and –800 V are applied to the drum, the sensor output (V100 and V800) is calibrated automatically (See page 2-5 for details).

2. VR, VD, VL potential detection (Fusing Temp ≥ 180°C) After about 30 seconds of drum conditio ning, VD and VL patterns are generated by using the previous grid bias voltage (VGRID) data and exposure lamp voltage (VLAMP) data to detect the VR, VD, VL data.

The machine calculates the new VGRID and VLA MP data using the detected VR, VD, VL data.

NOTE: The lens moves as VD & V L are checked. This allows each

pattern to be placed on the drum in alignment with the potential sensor.

FT6645/6655/6665 2-10 STM

Page 42

3. VD and VL corrections Using the calculated VGRID and VLAMP data, VR, VD, and VL patterns are developed again and the new VR, VD, and VL data are detecte d.

If both VD and VL data are within specifications, the new VGRID, VLAMP and development bias (VBB) are determined based on the new VD, VL, and VR values.

Specifications:

VD = –770 + VR ± 20 V VL = –140 + VR ± 20 V

If VD is outside specifications, VGRID is shifted one step (20V/step) . Then the VD pattern is measured again and VD is detected again. The same is done for VL and VLAMP.

The above process continues until both VD and VL fall within specifications. The graph on the previous page shows the example when only VL was outside specifications at the first VL detection and came within specifications after one VL correction (VLAMP is changed 0.5V/ste p , VGRID is changed 20V/step).

If V100 or V800 at drum potential sensor calibration is outside specifications or if VD or VL do not fall within specifications after VGRID or VLA MP are shifted to the maximum or minimum level, the machine stops VD or VL correction and uses the previous VGRID and VLAMP values during copying.

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

Related SC codes (see FSM troubleshooting section page 6-1 and 6-11):

Code Condition

361 Incomplete drum potential sensor calibration 364 Abnormal VD detection 365 Abnormal VL detection

Development bias is also decided by using VR as follows. VBB = VR + (–220)

4. ID sensor pattern potentia l detection This is performed to determin e ID Sensor Bias Voltage. The details ar e explained in the development control section (see page 2-16).

STM 2-11 FT6645/6655/6665

Page 43

1.4 IMAGE DENSITY CONTROL

VD (12 V)

GND

Sensor Output

1.4.1 Toner Density Sensor

A: VOUT (Gain data) is high.

OUT is within the specification.

B: V

OUT (Gain data) is low.

Sensor Output

(V)

REF

Developer consists of carrier par ticles (iro n) 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.

C: V

VOUT = VIN x

New Developer

1234

Toner Weight %

= 12 x

VIN

Main PCB

VOUT

AGC

Gain

256

Gain

256

TD Sensor

<Toner Density Sensor Initial Setting> When new developer with the standard toner concentration (2.0% by weight,

20 g of toner in 1000 g of develope r) is installed, developer initial setting must

be performed by using SP mode (

SP Adjustment – PAGE 1).

During this setting, the output voltage (VOUT) from the auto gain control circuit (AGC) on the main control board PCB varies to change the sensor output voltage from the tone r density (T D) sensor . This is done by changing the gain data, see below.

VOUT = VIN x

Gain Data

256

= 12 x

Gain Data

256

If the gain data is high, VOUT becomes high, and the sensor output voltage becomes high. As a result, the sensor characteristic becomes as illustrated by curve A. If the data is low, VOUT becomes low, and the sensor output voltage becom es low. As a result, the sensor characteristic shif ts as illustrated by curve C.

FT6645/6655/6665 2-12 STM

Page 44

By selecting the proper gain data, the sensor output is set within the targeted control level (VREF, VREF = 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.

Every copy cycle, toner density in the developer is detected. The sensor output voltage (VTD) during the detection cycle is compared with the toner supply level voltage (VREF).

VTD ≥ VREF: Add more toner

VTD < VREF: Add little toner

Sensor

Output (V)

VREF

12345

Toner Weight %

STM 2-13 FT6645/6655/6665

Page 45

To stabilize toner concentra tion, toner supply amount (to ner supp ly clutch on time) is controlled by referring to VREF and VTD. The toner supply amount is calculated at every copy. The toner supply amount is determined by using the following factors.

① VREF – VTD ② VREF – VTD’(VTD’ = VTD of the previous copy cycle)

VTD’

Previous Copy Last Copy Next Copy

VREF

By referring to these factors, the machine recognizes the difference between the current toner concen tration (VTD) and the target toner concentration (VREF). 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 amoun t precisely, toner concentra tion (image density) is kept at a constant level. Since the toner supply clutch on time updating is under fuzzy control, the relation among VTD, VTD’, VREF cannot be expressed by a simple algebra ic formula.

VTD

The image on the OPC drum changes due to variation of toner chargeability (influenced by the environm ent) even if the toner concentration is constant. The image density sensor (ID sensor) directly checks the image on the OPC drum and shifts VREF 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 being performe d.

FT6645/6655/6665 2-14 STM

Page 46

1.4.2 Image Density Sensor Detection

VSG Detection

3rd Series of Copies (17 copies)

[B]

[C]

[A]

Drum

Bias

LED

4 V

LED

VSG and VSP are checked by the ID sensor [A]. The ID sensor is located underneath the dru m cleaning section. There is no ID sensor pattern in the optics. A pattern image is made on the OPC drum by the charge corona unit [B] and the erase lamp [C].

VSG is the ID sensor output when checking the erased drum surface. VSP is the ID sensor output when checking the ID sensor pattern image.

To compensate for any variatio n 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

12345678 910111213 1415 29

Detection

1st Series of Copies (8 copies)

2nd Series of Copies (5

copies)

V Detection

SP Detection

VSP Detection

V Detection

VSG is detected every time the machine starts copying. During VSG detectio n, t he develop men t sleeve rollers do not rotate and no development bias is applied.

VSP is detected after copying is completed if 10 or more copies have been made since VSP was last detected. Since the transfer belt must be released when checking VSP, a VSP check cannot be done during contin uous copying .

STM 2-15 FT6645/6655/6665

Page 47

1.4.2.a ID Sensor Bias –700 V

Bias

While developing the ID sensor pattern, ID sensor bias is applied. ID sensor bias is determined during proce ss control data initial setting as follo ws:

1. Apply charge while grid voltage is –700 V to create the ID sensor patte rn.

2. Check the drum potential (VP) of the ID sensor pattern.

3. Adjust the ID sensor bias (VIDB) so that it satisfies the following formula.

VIDB = VP – (–300) (V)

= VP + 300 (V)

4. Change the bias to the calculated VIDB and detect VSP. VSG (detected

during V SG adjustment sequence in the process control data initial setting) and VSP are used to determine VREF data at process control data initial setting. VIDB is not changed until the next process contro l data initial setting is done.

After the series of copies is completed in the case that 10 or more copies have been made, VREF is updated by referring to the previous VREF (VREF’), VSG, VSP and the current TD sensor output (VTD).

Since this VREF data updating is under fuzzy control, the relationship among VREF, VREF’, VSG, VSP and VTD cannot be expressed by a simple algebraic formula.

VREF is updated not only in the case above, but also during developer initial setting and during process control data initial setting.

FT6645/6655/6665 2-16 STM

Page 48

Rev. 4/15/94

1.4.3 Sensor Abnormal Conditions

a. ID sensor (VSG,VSP) abnormal Whenever VSG falls under 2.5 V or VSP rises over 2.5 V, the CPU fixes the

VREF data and toner concentration is controlled only by using TD sensor output. This is the detect mode of toner supply.

VSG and VSP are still detected as usual during abnormal conditions and if output returns to normal levels (VSG ≥ 2.5 V, VSP ≤ 2.5 V), the CPU returns the toner concentration control to normal mode.

b. TD sensor (VTD) abnormal Whenever VTD 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 amo unt can be changed in four steps (4%, 7%, 11%, 14%) by using SP mode. The default fixed toner supply amount is 4%.

VTD is still detected as usual during the abnormal condition and if its output returns to a normal level, the CPU returns the toner concentration control to normal mode.

c. Drum Potential Sensor abnormal Whenever V100 rises over 0.7 V or V100 falls under 0.1 V or whenever V800

rises over 4.2 V or V800 falls under 2.7 V, the CPU also shifts the toner supply to the fixed supply mode, as for a TD sensor (VTD) abnormal condition.

For following SC codes, no code is indicated on the op panel but the SC counter is incremented .

Related SC codes. (See FSM troubleshooting section pages 6-1 and 6-8 thru 6-11):

Code Condition

351 Abnormal VSG Detection (VSG > 4.2 V) 352 Incomplete TD Sensor Initial Setting 353 Abnormal VSP Detection (VSP > 2.5 V) 354 Abnormal VSG Detection (VSG ≤ 2.5 V) 355 Abnormal VTD Detection (VTD > 4 V) 356 Abnormal VTD Detection (VTD < 0.5 V) 357 Abnormal VSP Detection (VSP/VSG ≥ 25%) 358 Abnormal VSP/VSG Detection (VSP/VSG < 2.5%) 361 Incomplete Drum Potential Sensor Calibration

STM 2-17 FT6645/6655/6665

Page 49

2. DRUM UNIT

2.1 OVERVIEW

7/8

The drum unit consists of the components as shown in the above illustrat ion. 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

7. Image Density Sensor

8. Drum Thermistor

9. Cleaning Brush

10. Toner Collection Coil

11. Cleaning Blade

12. Ozone Filter

13. Cleaning Filter

14. Charge Power Pack

15. Quenching Lamp

16. Main Charge Corona Unit

FT6645/6655/6665 2-18 STM

Page 50

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 electrica l charge when expose d to light. (Exp osur e to light

greatly increases the condu ctivity of a photocond uctor .)

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 remain s 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.

STM 2-19 FT6645/6655/6665

Page 51

Rev. 9/94

2.3 DRUM CHARGE

2.3.1 Overview

[A]

This copier uses a double corona wire scorotron system for drum charge. Two corona wires are require d to give sufficient negat ive charge on the dru m surface because of a rather high drum speed (330 mm/sec.) A095/A096 and (430mm/sec.) A097. The stainless steel grid plate makes the corona charge uniform and controls the amo unt of negat ive 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 also supplies the bias voltage to the grid plate. The grid bias is automatically controlled to maintain proper image density according to changes of the OPC drum potential due to dirt build up on the grid plate and charge corona casing.

FT6645/6655/6665 2-20 STM

Page 52

2.3.2 Air Flow Around the Drum

[B]

[A]

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 (O3) around the drum. The exhaust fan rotates slowly during stand -by and rot ates quickly during

copying to keep the temperatur e inside t he machin e constant .

STM 2-21 FT6645/6655/6665

Page 53

2.3.3 Charge Wire Cleaning Mechanism

[A]

[C]

[A]

[C]

[B]

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 preve nt 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 (hom e position). After 5000 or more copies are made and fusing temper atur e is less than 100°C after the main switch is turned on, the wire cleaner moto r turn s 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 ar row in the illustration), the wire cleaner pads clean the wires.

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

FT6645/6655/6665 2-22 STM

Page 54

2.4 ERASE

SE LE

2.4.1 Overview

LOES

LE: Lead edge erase margin 3.5 ± 2.5 mm SE: Side erase margin total of both sides 3 mm or less Lo: Original width Lc: Charged width of drum EL: Lead edge erase Es: Side erase

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

STM 2-23 FT6645/6655/6665

Page 55

2.4.2 Lead Edge and Trail Edge Erase

The entire line of LEDs turns on when the main motor turns o n. 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 appearin g 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 mode: PAGE 3). When the scanner reaches the return position, the charge corona, the grid

bias, and the exposure lamp turn off. However , the ch arg ed 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 pre vents developing unnecessary parts of the drum surface, red ucing 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 rea r sides of the drum surf ace in reductio n 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.

In the platen cover mode, the horizontal original standard position on the exposure glass is the left 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.

FT6645/6655/6665 2-24 STM

Page 56

2.5 CLEANING

[C]

2.5.1 Overview

[D]

[A]

[B]

4 mm

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, a pre-cleaning coro na and cleaning bias system 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 the cleaning blade scapes off any remaining toner and dro ps it into the cleaning brush. Toner on the cleaning brush is scraped off by the mylar [C] and falls to the toner collection coil [D]. Toner is transporte d to the toner collectio n bottle by the toner collection coil.

To remove the accumulate d 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 then removed by the cleaning brush.

STM 2-25 FT6645/6655/6665

Page 57

2.5.2 Drive Mechanism

[C]

[E]

[B]

[D]

The drive force from the main mot or is transm itted to the cleanin g unit drive gear via the timing belt [A] and the cleaning unit coupling [B]. The cleaning unit drive gear [C] then transmits the for ce to the front side t hro ugh the cleaning brush [D]. The force at the front side is used for the toner collection coil gear [E].

[A]

FT6645/6655/6665 2-26 STM

Page 58

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

[C]

[A]

[D]

[B]

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 transportatio n, 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.

STM 2-27 FT6645/6655/6665

Page 59

Rev. 12/93

[A]

[C]

2.5.4 Toner Collection Mechanism

[H]

[B]

[E]

[D]

[G]

[F]

Toner collected by the cleaning unit is transpor ted to the toner collection bottle [A] through the toner collectio n tubes. Thr ee helical coils are used for toner transport.

One coil [B] is driven by the main motor via drive belts, the second [H] is driven by the cleaning brush and the third coil [C] is driven by an independent toner collection drive motor [D].

The actuator disk [E] on the toner collection drive moto r 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] becomes full, the tone r pressu re in the bottle increases and presses the gear [F] against the toner overflow switch [G]. After the toner overflow switch is activated, 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 (item [D] on next page).

FT6645/6655/6665 2-28 STM

Page 60

Rev. 10/94

[B]

[C]

[A]

[D]

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 Pre-Transfer Lamp (PTL)

After the latent image is developed but before the image is transfer red to the copy paper, the drum surface is illuminated by the pre-transfer lamp [C]. This illumination reduces the nega tive poten tial on the drum surface. This prevents toner part icles from being re-a ttracted to the negatively charged drum during the paper separation process. It also makes transfer and paper separation easier.

The Pre-Transfer lamp consists of a line of LEDs extending across the full width of the drum.

Red illuminating LEDs are used to reduce ultra violet light which would cause light fatique on the OPC drum.

2.5.7 Toner Collection Bottle Set Detection

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

STM 2-29 FT6645/6655/6665

Page 61

Rev. 10/94

2.6 QUENCHING

[A]

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

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

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

FT6645/6655/6665 2-30 STM

Page 62

Rev. 7/94

[D]

3. OPTICS

3.1 OVERVIEW

[A]

[B]

[E]

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.

[C]

To increase the copy speed from 55cpm to 65 cpm, not only the paper transport speed but also the copy process speed (scanner motor speed A095/A096: 330mm/sec., A097: 430mm/sec.) is increased. To compensate for this, stronger exposure light is required. Therefore, the wattage of the exposure lamp is changed.

On these models a halogen lamp is used for the exposure lamp [A]. (A095/A096: 85V, 200 W; A097: 85V, 225W). The 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 reduct ion a nd enlar gem ent mod es, t he third scanner unit [C] (4th and 5th mirror s) positio n 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 when the main switch is turned off to prevent the moisture from forming on the optics.

STM 2-31 FT6645/6655/6665

Page 63

[C]

Rev. 7/94

3.2 SCANNER DRIVE

[A]

[D]

[B]

[E]

A dc servo motor is used as the scanner drive motor [A]. Scanner drive speed is 330 mm/sec. (A095/A096 copiers) and 430mm/sec. (A097 copier) during forward scannin g, and 1950 mm /sec. when the scanne r returns to home.

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 moves at one half the speed of the first scanner.

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

FT6645/6655/6665 2-32 STM

Page 64

3.3 VERTICAL LENS DRIVE

[A]

Rev. 4/15/94

[B]

HP (100%)

ReduceEnlarge

(Enlarge → HP) (Reduce → HP)

(Enlarge → Enlarge) (Reduce → Reduce)

(Enlarge → Reduce)

(Reduce → Enlarge)

steps30 30 30 30

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

A stepping motor (approx. 0.095 mm/step) and drive belt are used to drive the lens. 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 vertica l 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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3.4 HORIZONTAL LENS DRIVE

[A]

Enlarge

steps

Reduce

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 adjust men t for each feed statio n can be done easily by using SP mode ( SP Adjustment mode: PAGE 4).

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Page 66

3.5 HORIZONTAL LENS POSITIONING

3.5.1 For Original Position

Platen DJF

100%

[A]

[C]

143.5

RDH (Center)

Horizontal

2.5

Lens Position

Copy Paper

[B]

There are three stand ard original positio ns 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 tra nspor t path (5 mm from the rea r sca le). 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

100%

Lens Position

Horizontal

Copy Paper

To keep high paper feed perfor mance, 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.

STM 2-35 FT6645/6655/6665

Page 67

Copy Paper

50%

Rev. 4/15/94

3.5.3 For Reproduction Ratio

Original Rear Edge

100% 50%

Original

200%

100%

200%

3rd Scanner Position

When the reproduction ratio is changed, the vert ical 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 vertical 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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Page 68

3.6 3RD SCANNER DRIVE

[B]

[A]

(Initialize)

(Reduce/Enlarge → HP)

(Reduce/Enlarge → Reduce/Enlarge)

(Reduce/Enlarge →Enlarge/Reduce)

40 steps 40 steps

To compensate the focus for repr oduction 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 positio n based on the number of motor drive pulses.

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Page 69

3.7 OPTICS CONTROL CIRCUIT

Optic Thermisto r

Scanner Drive

Horizontal Lens Drive

Vertical Lens Drive

3rd Scanner Drive

Optic Cooling Fan

Main Control Board

Main CPU

Sensors

Data Bus

Optics Control Board

Optics Control CPU

M M M M

Encoder

Exposure Lamp

AC Drive Board

The optic control board communicates with the main board through a data bus. The optics control board monitors all th e sensor signals, encoder output, thermistor outp ut 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.

The optics thermistor senses the temperature of the optics cavity and controls the on/off operation of the optics fan.

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Page 70

3.8 AUTOMATIC IMAGE DENSITY CONTROL SYSTEM (ADS)

[B]

[A]

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 adjust s the ADS gain data automatically to make the output 2.7 V. This gain data is stored in the RAM board.

STM 2-39 FT6645/6655/6665

Page 71

Rev. 12/93

90 mm

20 mm

[V]

9.7

A =

(mm)

M = 1.0 (m = 50 ~ 100)

M = B =

(m = 101 ~ 200)

100

8.25

x 100 (mm)

m m: reproduction ratio

(50 ~ 200)

ADS Sensor Output

ADS Original Voltage

Peak hold

In the full size mo de, the CPU samples the ADS sensor output when the scanner scans the original from 9.7 mm to 18 mm [B] from the left scale edge. The CPU takes the maximum ADS sensor output during this sampling period and compares it with the stor ed ADS refe ren ce voltage to deter mine the proper developm ent bias voltage. (See developm ent bias control section for additional details.)

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

FT6645/6655/6665 2-40 STM

Page 72

Darker

Rev. 4/15/94

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.

Dev. Bias Voltage VBM (negative)

Exposure Lamp Voltage

V VBB –60

LAMP +4.5

LAMP +3.0

VLAMP +0 .5

LAMP –1.5

LAMP –3.5

V V

LAMP –5.5

BB –90

VBB

LAMP

Lighter

VLAMP: Exposure lamp voltage at ID level 4.

This value is determined at process control data initial setting.

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

This value is determined at process control data initial setting.

Manual ID Position

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Page 73

3.10 UNEVEN LIGHT INTENSITY CORRECTION

[D]

original

Shading plate

[D]

exposure intensity

illumination distribution

[A] [B] [C]

The entire exposure lamp surface is fr osted to ensure even exposur e. 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 compensat es the light intensity when the lens horizo ntal position is shifted ([A] to [C]).

Also three shading mylars [D] intercept any d iffuse d reflect ed light from outside the light path.

FT6645/6655/6665 2-42 STM

Page 74

3.11 ORIGINAL SIZE DETECTION IN PLATEN MODE

[E]

[B]

[D]

[C]

[A]

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.

STM 2-43 FT6645/6655/6665

Page 75

Rev. 4/15/94

[A]

Width Sensor Length Sensor 2 Length Sensor 1

9 8 7 6* 5 4* X2* 3 2 1 X1*

11 x 17 O O O 1 O 1 O O O O O

1/2 x 14 1OO1O1OOO1O

8 8

1/2 x 11 1OO1O1O111O

11 x 8

1/2 OOO1O1O111O

1/2 x 81/2 1111O1O111O

5 8

1/2 x 51/2 1OO111O111O

NOTE: -1: Active -0: Inactive

*Sensors #4 and #6 are not used for LT/DLT version machines. Their values are always 1. Sensors #X2 and X1 are not used for LT/DLT version m achin es.

Their values are always ø.

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 produ ctivity.

FT6645/6655/6665 2-44 STM

Page 76

4. DEVELOPMENT

4.1 OVERVIEW

[C]

[D]

[A] This copier uses a double roller (diamet er 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 edge s of the half-tone areas, and black cross points.

[B]

The paddle roller [A] picks up developer in its paddles and transpor ts 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 rolle rs continues to turn, carrying the developer to the OPC drum [D]. When the developer brush contacts the drum surfa ce, t he negatively charged areas of the drum surface attract and hold the positively charged toner. In this way, the latent image is developed.

The development rolle r 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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Page 77

4.2 DRIVE MECHANISM

[C]

[D]

[A]

[B]

[E]

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 nor mal 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.

FT6645/6655/6665 2-46 STM

Page 78

4.3 CROSSMIXING

[D]

[C]

[A]

[B]

[C]

[E]

[F]

[E]

[F]

[D]

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 deve lopm ent rolle rs form s the magnetic brush and develops the laten t image on t he drum. The par t th at 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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Page 79

4.4 DEVELOPMENT BIAS

4.4.1 Overview

[A]

[B]

[C]

The high voltage control board [A] applies the negative development bias to the lower sleeve roller through the recepta cle [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 conduct ive 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.

FT6645/6655/6665 2-48 STM

Page 80

4.4.2 Bias Control In Copy Cycle

VL Light

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

ADS Mode: VB = VBB + VBU + VBMG + VBA Manua l ID Mode: VB = VBB + VBU + VBMG+ VBM

VB: Total bias VBB: Base bias VBA: ADS Compensation VBU: User Tool mode ID Selection Compensation VBMG: Magnificat ion Compe nsatio n VBM: Manual ID Selection Compensation

1) Base Bias (VBB)

[V]

Drum Potential

Dark

Original Density

As explained in the process control section, the base bias for develo pme nt is determined by the residual volta ge (VR ) measured in process control data initial setting.

VBB = VR + (–220)

2) ADS Compensation (V BA)

VBA (negative)

–300

1.02 V

122.7

1 2 2.3

Dark V

ADS (V) Light

According to the original background density, the bias is compensated. The compensation value is determ ined with the voltage measur ed by the ADS sensor (ADS sensor output: VADS) as follows:

VBA = 234 x (VADS –2.3)

NOTE: VBA has a limited range from 0 V to –300 V.

STM 2-49 FT6645/6655/6665

Page 81

Darker

Rev. 4/15/94

3) Manual ID Select ion Posit ion Comp en sation (VBM)

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

BB –90

VBB

LAMP

Lighter

Dev. Bias Voltage VBM (negative)

Exposure Lamp Voltage

V VBB –60

LAMP +4.5

LAMP +3.0

VLAMP +0 .5

LAMP –1.5

LAMP –3.5

V V

LAMP –5.5

Manual ID Position

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

process control data initial setting.

4) User Tool Mode ID Selection Compensation (VBU)

In the User Tool mode, the image density level can be selected from five steps. The VBU is determined by the User Tool ID position setting as follows:

VBU (negative)

Lighter Darker

–60 –30

54321

+30

+60

FT6645/6655/6665 2-50 STM

User Tool ID Position

Page 82

5) Magnific ati on Comp ens ati on (VBMG)

142%

VBMG is determined by the selected reproduction ratio as follows:

–100

Dev. Bias Voltage (negative)

–60 –40

–30

–20

50%

62%

81%

116%

115%80%61%

122%

123%

141% 160%

161%

4.4.3 Bias Control Out of Copy Cycle

To hold the toner on the sleeve rollers while the developme nt sleeve roller s are rotating without imag e developm ent , a consta nt –300 V bias is applied.

STM 2-51 FT6645/6655/6665

Page 83

4.4.4 ID Sensor Pattern Bias

–700 V

Bias

While developing the ID sensor pattern, ID sensor bias is applied. ID sensor bias is determined during proce ss control data initial setting as follo ws:

1. Apply charge while grid voltage is -700V to create t he ID sensor patte rn.

2. Check the drum potential (VP) of the ID sensor pattern.

3. Adjust the ID sensor bias (VIDB) so that it satisfies the following formula. VIDB = VP – (–300)

= VP + 300 (V)

4. Change the bias to the calculated VIDB and detect VSP. VSG (detected

FT6645/6655/6665 2-52 STM

Page 84

4.5 TONER SUPPLY

[E]

[F]

4.5.1 Toner Supply Mechanism

[A]

[B]

[F]

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

The toner supply magnetic clutch [A] located in the development motor assembly [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 tu rn past the opening, the toner falls into the developm ent unit.

[B]

[C]

[D]

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Page 85

4.5.1a Toner Density Detection

Developer consists of carrier par ticles (iro n) and toner particles (resin and carbon). Toner concentration is measured by the toner density sensor. Inside the developer unit, developer passes through a magnetic field created by coils inside the toner density sensor (A). When the toner concentration falls, the voltage output by the toner density sensor changes accordingly and the toner supply clutch is activated.

New developer has a standard toner concen tration of 2% by weight, 20g of toner within the 1000g of developer. When new developer is installed, developer initial setting must be perfor med.

[A]

FT6645/6655/6665 2-54 STM

Page 86

4.5.2 Toner End Detection

[A]

The toner end sensor [A] detects if sufficient toner rema ins in the toner hopper. The toner end sensor monitors the toner end condition each time 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 copy cycle (one detection pulse per 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 the 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 opene d and closed, the machine drives the toner supply mech anism 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.

STM 2-55 FT6645/6655/6665

Page 87

Rev. 4/15/94

4.5.3 Toner Supply Control

By using an SP mode ( Adjustment mode: PAGE 7), the following 3 kinds

of toner supply controls can be selected.

• Auto Process Control Mode

• De tect Mod e

• Fixed Mod e

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.

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.

FT6645/6655/6665 2-56 STM

Page 88

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 the VREF 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 outp ut is upda ted unde r the following conditions:

1. During toner density sensor initial settin g

2. During process control data initial settin g

3. After the copy job is completed when 10 or more copies have been made since the last update. (VSP check)

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

Rev. 4/15/94

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

( Adjustment mode:

PAGE 7). There is no overtoning detection mechanism. In TD sensor abnormal condition or Drum Potential sensor abnormal

condition the machine automatically enters this mode.

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Page 89

4.5.4 Bottle Drive Mechanism

[C]

[D]

[E]

[A]

[B]

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

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

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 re move d 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 for 0.7 seconds when the toner end sensor turns on twice continually.

FT6645/6655/6665 2-58 STM

Page 90

5. IMAGE TRANSFER

5.1 PRE-TRANSFER LAMP

[A]

The pre-tran sfer 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 transfer red to the copy paper, the drum surface is illuminated by the pre-transfer lamp. This illumination reduces the nega tive potential on the drum surface char ged 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.

STM 2-59 FT6645/6655/6665

Page 91

5.2 IMAGE TRANSFER AND PAPER SEPARATION

OVERVIEW

[E]

[A]

[D]

[B]

[F]

[C]

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 pote ntial and attr acts 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 consta nt transfer current.

[E] Transfer belt cleaning blade

Removes toner attach ed on the transf er belt to p reve nt the rear side of the paper from being stained.

[F] Discharge plate

Helps paper separation from the transfer belt by discharging the remaining nega tive charg e on the transfer belt.

FT6645/6655/6665 2-60 STM

Page 92

5.3 IMAGE TRANSFER AND PAPER SEPARATION

[A]

–1.3 K~ –1.8KV

MECHANISM

The registration rollers [A] start 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 OPC drum. The lift lever is driven by a solenoid

[D]

[C]

[A]

[B]

Then a negative transfer bias –1.5 K ~ –2.0 KV is applied to the transfer bias roller [F] and attracts the positively charged toner [G] from the OPC drum. It also attracts the paper and separates the paper from the OPC drum.

[E]

–800 V

[F]

[G]

–1.5 K ~ 2.0 KV

STM 2-61 FT6645/6655/6665

Page 93

Rev. 4/15/94

[B]

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 tran sfer belt is discharged to ground by the discharge plate [A].

The transfer power pack [B] inside the transfer belt unit monitors the current fed back from the discharge plate to adjust the transfer curre nt. This way, the current stays constant even if the paper, environm ental conditions, and the transfer belt surface resistance are changed.

[A]

[B]

[A]

FT6645/6655/6665 2-62 STM

Page 94

5.4 TRANSFER BELT UNIT LIFT MECHANISM

[E]

[C]

[E]

[A]

[F]

[D]

[B]

The transfer belt lift solenoid [A] located inside the tra nsfer 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 soleno id to raise the transf er 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 patt ern on the OPC drum from being rubbed by the transfer belt becau se the transfer belt is located between the development unit and the ID sensor.

2. To decrease the load to the tran sfer belt cleaning b lade. It is better to have toner from non-image areas removed by the drum’s cleaning system than by the transfer belt’s cleanin g system (for example Vd , VL, and ID patterns ).

3. To prevent chang e of OPC drum characte ristics by the influence of additives inside the rubber belt.

STM 2-63 FT6645/6655/6665

Page 95

5.5 PAPER TRANSPORTATION AND BELT DRIVE

[E] [E]

MECHANISM

[C]

[A]

[F]

[B]

[F]

[D]

The transfer belt is driven by the main drive motor [A] through belt and gears. Since the transfer belt electr ically attr acts the paper [B], the transpo rt fan is not required.

The charge on the transfer belt is discharged by the discharge plate to reduce paper attra ction and paper is separated by the paper st iffne ss 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.

FT6645/6655/6665 2-64 STM

Page 96

5.6 TRANSFER BELT CLEANING MECHANISM

[D]

[A]

[B]

[C]

Some toner may adhere t o transf er belt when pape r 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 adher ed tone r must be rem oved 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 clea ning. The surface of the transfer belt is coated to make it smooth and so prevent the cleanin g blade from being flipped by the transfer belt.

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 rub s the seal so that the seal [D] removes the toner or paper dust on the cleaning blade edge.

STM 2-65 FT6645/6655/6665

Page 97

5.7 TONER COLLECTION MECHANISM

[B]

[A]

Rev. 4/15/94

Through idle gears [A], transfer belt drive is transmitted to the toner collection coil [B]. The toner collection coil transports the collecte d toner to the toner collection bottle. See page 2-28 for details.

FT6645/6655/6665 2-66 STM

Page 98

6. PAPER FEED

Rev. 7/94

6.1 OVERVIEW

[A]

[B]

[A]

[B]

[C]

This model has three drawer tra y paper feed stations. The following table shows the configuration of each feed station of the A095, A096 and A097 copiers.

Feed station FT6645 (A095 copier) FT6655/6665 (A096/A097) copiers

1st 550 sheets tray 500 + 500 sheets tandem feed tray

2nd 550 sheets universal tray 550 sheets universal tray

3rd 550 sheets tray 1500 sheets built-in LCT

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.

STM 2-67 FT6645/6655/6665

Page 99

6.2 FRR FEED SYSTEM

[A]

[B]

[C]

This copier uses an FRR paper feed system using thr ee roller s.

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 separ atio n roller s [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 Separati o n Rollers

There is a one-way bearing inside the feed roller so it can turn only in one direction. The separa tion rolle r 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.

FT6645/6655/6665 2-68 STM

Page 100

[B]

[A]

F3 F1

[B]

[A]

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 rolle r [B] and the paper (F 2) is greate r 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 (F 3), becomes less than F1 because the friction between the two sheets is small. So, the separation roller starts tu rning clockwise and drives the second sheet back to the tray.

STM 2-69 FT6645/6655/6665

Ricoh FT 6645 Diagram

Specifications and Main Features

Frequently Asked Questions

User Manual

3.1 OVERVIEW

3.2 SCANNER DRIVE

3.3 VERTICAL LENS DRIVE

3.4 HORIZONTAL LENS DRIVE

3.5 HORIZONTAL LENS POSITIONING

3.6 3RD SCANNER DRIVE

3.7 OPTICS CONTROL CIRCUIT

3.8 AUTOMATIC IMAGE DENSITY CONTROL SYSTEM (ADS)

3.9 MANUAL IMAGE DENSITY CONTROL

4.1 OVERVIEW

4.2 DRIVE MECHANISM

4.3 CROSSMIXING

4.4 DEVELOPMENT BIAS

4.5 TONER SUPPLY

5.1 PRE-TRANSFER LAMP

5.4 TRANSFER BELT UNIT LIFT MECHANISM

5.6 TRANSFER BELT CLEANING MECHANISM

5.7 TONER COLLECTION MECHANISM

6.1 OVERVIEW

6.2 FRR FEED SYSTEM