Ricoh FT6645 Service manual

SECTION 1

OVERALL MACHINE

INFORMATION

23 April 1993 SPECIFICATIONS

1. SPECIFICATIONS

Configuration: Console Copy Process: Dry electrostatic transfer system Toner Supply Control: Fuzzy Control Photoconducto r: 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

Overall

Information

Reproduction Ratios: 4 Enlargement and 6 Red uction

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%

1-1

SPECIFICATIONS 23 April 1993

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

220 ~ 240V, 50Hz/60Hz, more than 10A (f or EU and AA)

Power Consumption: A095 and A096 copiers

Copier only Full system* Warm-up 0.9 kVA 0.9 kVA Stand-by 0.25 kVA 0.25 kVA

Copying 1.2 kVA 1.3 kVA

Maximum 1.45 kVA 1.5 kVA

*Full System:

• Mainframe with dual job feeder, compact

sorter stapler and 3,500-she et la rge capa city tray

• Mainframe with dual job feeder, floor type

sorter stapler and 3,500-she et la rge capa city tray

Noise Emission:

sound pressure level: The measurements are made according to ISO7779

• Mainframe with recirculating document

handler, finisher and 3,500-sh ee t larg e capacity tray

Copier only Full system*

Copying 55 dB (A) 61 dB (A)

Full System:

• Mainframe with dual job feeder, compact

sorter stapler and 3,500-she et la rge capa city tray

• Mainframe with dual job feeder, floor type

sorter stapler and 3,500-she et la rge capa city tray

• Mainframe with recirculating document

handler, finisher and 3,500-sh ee t larg e capacity tray

1-2

23 April 1993 SPECIFICATIONS

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 cove r )

Weight: Copier only:(Without the optional platen cover

= Approximately 2 kg) A095 copier: Approximately 151 kg A096 copier: Approximately 163 kg

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

A4/LT (sideways) A3/DLT B4/LG A095 copier 45 23 27 A096 copier 55 28 35

Warm-up Time: Less than 5 minutes (20°C) First Copy Time: 3.1 seconds (A4/81/2" x 11" sideways from the

1st feed station) Copy Number Input: Numbe r keys, 1 to 999 (count up or count down) Manual Image Density

7 steps Selection:

Overall

Information

Automatic Reset: 1 minute standard se tt ing; can also be set from 1

second to 999 secon ds or no auto reset. Copy Paper Capacity: • By-pass feed table: ap pro ximat ely 50 shee ts

• Paper tray: approximately 550 sheets

• Tandem tray: approximately 500 sheets

• Large capacity tray: approximately 1500

sheets

1-3

SPECIFICATIONS 23 April 1993

Toner Replenishment: 1,100 g/cartridge Optional Equipment: • Platen cover

• Dual job feeder

• Recirculating document handler

• 20 bin sorter stapler (Floor type)

• 20 bin compact sorter stapler

• Finisher

• 3500-sheet Large capacity tray

• Receiving Tray

1-4

23 April 1993 MACHINE CONFIGURATION

2. MACHINE CONFIGURATION

2.1 COPIER OVERVIEW

There are two types of mainfra me.

A095 copier

Three 550-sheet paper trays Optional 3,500-sheet large capacity tray

Overall

Information

550 550

550

A096 copier

500 x 2 or 500 550

(3,500)

Tandem paper tray (including two 500-sheet paper tray) One 550-sheet paper t ray 1,500-sheet built-in large capa city tra y Optional 3,500-sheet large capacity tray

(3,500)

1,500

1-5

3,500-sheets large capacity tray (A380)

MACHINE CONFIGURATION 23 April 1993

2.2 SYSTEM OVERVI E W

System A

(The mainframe (A095) with du al job fee der and compa ct sorter stapler)

Dual job feeder (A376)

Compact sorter stapler (A374)

System B

(Mainframe type (A095/A096) with dual job feeder and floor type sorter stapler. The mainframe in the illustrat ion belo w is the A096.)

Dual job feeder (A376)

Floor type sorter stapler (A377)

1-6

3,500-sheets large capacity tray (A380)

23 April 1993 MACHINE CONFIGURATION

System C

(The mainframe (A096) with recircu lating document handler and fin isher)

Finisher (A379)

Recirculating document hand ler (A3 78 )

Overall

Information

1-7

COPY PROCESS AROUND THE DRUM 23 April 1993

3. COPY PROCESS AROUND THE DRUM

1. OPC DRUM

The organic photo conductive (OPC) drum (10 0 mm diame te r) has hig h resistance in the dark and low resistance under light.

2. DRUM CHARGE

In the dark, the charge corona unit gives a uniform negative ch arg e to the OPC drum. The charge remains on the surfa ce of the drum. The amo unt of negative charge on the drum is propo rtio na l to the ne gative grid bias voltage applied to the grid plat e on the charg e coro na unit .

3. EXPOSURE

An image of the original is reflected to the OPC drum surfa ce via th e optics section. The charge on the drum su rfa ce is dissipated in direct proportion to the intensity of the reflected light, thus producing an electrical late nt ima ge on the drum surface.

The amount of charge remainin g as a laten t imag e on the drum depe nds on the exposure lamp intensity controlled by the exposure lamp voltage.

4. ERASE

The erase lamp illuminates the areas of th e cha rge d dru m su rfa ce th at will not be used for the copy image. The resistance of drum in the illuminated areas drops and the charge on those areas dissipates.

1-8

23 April 1993 COPY PROCESS AROUND THE DRUM

5. DRUM POTENTIAL SENSOR

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

6. DEVELOPMENT Positively charged toner is attra cte d to the negat ively charged areas of the drum, thus developing the latent ima ge. (The posit ive trib oe lect ric charg e of the toner is caused by friction between the carrier and toner particle s.)

The development bias volt ag e ap plied to the developmen t rolle r shaft controls two things:

1) The threshold level if tone r is attracted to the drum or toner remain s on the development ro ller.

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

The higher the negative develo pme nt bias volt ag e is, th e less toner is attracted to the dru m surface.

7. PRE-TRANSFER LAMP (PTL)

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

8. IMAGE TRANSFER

Paper is fed to the drum surface at the prop er timing so as to align the copy paper and the develope d image on the drum surface. Then, a neg at ive charge is applied to the reverse side of the copy paper by th e transfer belt, producing an electrical force which pulls the toner particles from the drum surface onto the copy paper. At the same time, the copy paper is electrically attracted to the tra nsf er be lt.

Overall

Information

9. PAPER SEPARATION

Paper separates from the OP C drum by th e ele ctrica l att raction between the paper and the transfer belt. The pick-o ff pawls help to separate the paper from the drum.

10. CLEANING

The cleaning brush remo ves toner remaining on the dru m after image transfer and the clean ing blade scrapes off all the rema ining toner.

11. QUENCHING

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

1-9

MECHANICAL COMPONENT LAYOUT 23 April 1993

4. MECHANICAL COMPONENT LAYOUT

14 15 16 17

19 20

1-10

23 April 1993 MECHANICAL COMPONENT LAYOUT

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

22. Registration Rollers

23. Transfer Belt

24. Vertical Transport Rollers

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 Bott le

29. Transfer Belt Cleaning Blade

30. Hot Roller

31. Pressure Roller

32. Jogger Fences

Overall

Information

14. Erase Unit

15. Drum Potential Sensor

16. Toner Hopper

17. Development Unit

18. Pre-Transfer Lamp

19. Pick-up Roller

20. Feed Roller

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

1-11

DRIVE LAYOUT 23 April 1993

5. DRIVE LAYOUT

❾

❽

❼

❻

❺

❶

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

1-12

23 April 1993 PAPER PATH

6. PAPER PATH

6.1 STANDARD COPYING

[F]

[D]

[C]

[B]

Overall

Information

[E]

Paper feed begins from the exte rior LCT, by-pa ss fee d ta ble or pap er fe ed stations in the paper tray unit . The copy pa pe r the n follows on e of two path s inside the copier. The path fo llowe d depe nd s on which mode the operator has selected. For copy processing, all sheets follow the same pat hs fro m t he paper feed mechanism [A] through the registration rollers [B ], transfer belt [C], and fusing unit [D] . Af ter that, copies are delivere d to the sorter bins [E] or proof tray [F], however, 2 sided copie s are diverted for further processing.

[A]

1-13

PAPER PATH 23 April 1993

6.2 MULTIPLE 2-SIDED CO PYING

a. Front Side

[B]

[A]

[D]

[C]

b. Rear Side

In this mode the junction gat e [A ] directs sheets exiting th e fu sing unit to the duplex tray entrance. Aft er that, all sheets follo w the pat h th rou gh the dup lex entrance rollers [B].

After all front side cop ying is comp let ed , the sheets on the duple x tray are fed in order from the bottom to the top and follow the path throu gh the duplex feed mechanism and vertical transport rollers [C] to the registration rollers [D]. After that , th ese sheets follow the same pat h as sta nd ard copying from the registration rollers to the sorter.

1-14

23 April 1993 ELECTRICAL COMPONENT DESCRIPTION

7. ELECTRICAL COMPONENT DESCRIPTION

Refer to the electrical compone nt layou t on the reverse side of the att ach ed Point to Point for symbols and ind ex numbers.

Symbol Name Function Index

No.

Motors

Overall

Information

M 1 Scanner Drive Drives the 1st and 2nd scanne rs

(dc servo).

M 2 Exhaust Fan Removes 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 Horizont al Drive Shifts the lens horizontal position. 51 M11 Lens Vertica l Drive Shifts the lens vertical position . 52

Drives the main charge wire

cleaner to clean the charge wire.

square the paper stack in th e

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 Lif t Raises the bottom pla te in the

2nd paper tray. M17 Toner Colle ction Transport s the collect ed toner to

the toner collection bott le.

1-15

ELECTRICAL COMPONENT DESCRIPTION 23 April 1993

Symbol Name Function Index

No.

M18 3rd Lift

(A095 copier only)

M19 Side Fen ce Drive

(A096 copier only)

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 copier only)

Moves the papers stacked in the

left tandem tray to the right

tandem tray. M21 LCT Motor

(A096 copier only)

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 tra nsport rollers

to transport the paper to the

vertical transport rollers.

MC5 Duplex Feed S tarts pa per fee d from the duplex

tray to the duplex transport rollers.

MC6 1st Feed Starts paper fee d 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

1-16

23 April 1993 ELECTRICAL COMPONENT DESCRIPTION

Symbol Name Function Index

No.

Switches

SW1 By-pass Table Detects if the by-pass feed tab le

is open or closed.

SW2 Front Door Safety Cuts the ac power line and

detects if the front door is open or

not.

SW3 1st Tray Set

Detects if the 1st tray is set or no t. 66

(A095 copier only)

SW4 2nd Paper Size Determines what size paper is in

the 2nd (universal) paper tray.

SW5 Toner Overflow Detects when the toner collection

bottle is full.

SW6 Toner Collection

Bottle Set

SW7 Lower Front Door

Safety

SW8 3rd Tray Set

Detects if the toner collection

bottle is set or not.

Detects if the front door is open

or not.

Detects if the 3rd tray is set or no t. 84

(A095 copier only)

Overall

Information

SW9 Main Provides power to the copier 122

SW10 Tray Down

Lowers the LCT bottom plate. 126

(A096 copier only)

Solenoids

SOL 1 Junction Gate Moves the junction gate to dire ct

copies to the duplex t ray or to the

paper exit.

SOL 2 Duplex Positioning Controls the up-down move ment

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 around this

area.

SOL 5 Transfer Belt

Positioning

Controls the up-down movement

of the transfer belt un it.

1-17

ELECTRICAL COMPONENT DESCRIPTION 23 April 1993

Symbol Name Function Index

No.

SOL 6 Pressure Arm Presses the paper on the duplex

tray against the duple x fee d

rollers.

SOL 7 Tandem Lock Locks the left tandem feed tray

and separates the righ t an d lef t

tandem trays.

SOL 8 1st Pick-up Controls the up-down movemen t

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-do wn movement

of the pick-up roller in the 2nd

feed station.

SOL11 2nd Separat ion Roller Controls the up-down movement

of the separation roller in the 2nd

feed station.

SOL12 3rd Pick-up Controls th e up -do wn movement

of the pick-up roller in the 3rd

feed station.

100

102

103

105

SOL13 3rd Separa tio n Rolle r Controls the up-down move men t

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 th e original

has been removed or not.

106

1-18

23 April 1993 ELECTRICAL COMPONENT DESCRIPTION

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 th e CPU that there is no

paper in the by-pass feed tab le.

S 8 Guide Plate Position I nforms th e CPU if the

registration guid e pla te is closed

or not.

S 9 Jogger HP Detects if the duplex jogg er

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 Detects the leading edge of the

paper to determine the duplex

transport clutch on timing .

Overall

Information

S12 Duplex Entrance

Sensor

Detects the leading edge of the

paper to determine the duplex

feed clutch off timing.

S13 Duplex Paper End Detects paper in the duplex tray. 13 S14 Duplex Transport Detects the lea din g ed ge of th e

14 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 ba ckgro un d de nsit y

20 of the original.

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

1-19

ELECTRICAL COMPONENT DESCRIPTION 23 April 1993

Symbol Name Function Index

No.

S22 By-Pass Paper Size Informs the CPU what size pape r

26 is in the by-pass feed table.

S23 Toner Density Senses the amount of toner in th e

27 black developer.

S24 Registration Detects misfeeds and controls

28 registration clutch off-on timing.

S25 Toner End Detects toner end cond itio n. 30 S26 Auto-Response Returns the display fro m 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 fe ed heig ht 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 co llect ion motor operation.

S36 2nd Lift Detects the correct fe ed heig ht of

the 2nd cassette.

S37 3rd Lift Detects th e 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.

1-20

23 April 1993 ELECTRICAL COMPONENT DESCRIPTION

Symbol Name Function Index

No.

S40 3rd Paper Feed Controls 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 copier only)

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 copier only)

S44 Rear Fence Return

(A096 copier only)

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

S45 Rear Fence HP

(A096 copier only)

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 copier only)

Overall

Information

S47 LCT Near End

(A096 copier only)

S48 Tray Down

(A096 copier only)

Detects the paper nea r e nd condition.

Detects when the tra y is completely lowered to stop the LCT motor.

S49 Tray Paper Set

(A096 copier only)

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 fun ctio ns. 109 PCB 3 Optic Control Controls all optics components. 110 PCB 4 High Voltage Con tro l Controls the output of both power

packs and development bias.

123

124

125

108

111

1-21

ELECTRICAL COMPONENT DESCRIPTION 23 April 1993

Symbol Name Function Index

No.

PCB 5 Paper Feed Cont rol Controls all components in the

paper bank.

PCB 6 DC Power Supply

Provides DC power. 113

Unit PCB 7 Guidance Controls the guidance displa y. 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 Provides heat to the hot roller. 32 L3 Quenching Neutralizes any charge remaining

on the drum surface after

cleaning. L4 Erase Discharg es th e drum outside the

image area. L5 Pre-transfer Reduces the charge on the dru m

surface before transfer.

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 motor

functions.

Others

TS1 Optics Thermoswitch Opens the exposure lamp circuit

if the optics unit overheats.

TF1 Fusing Thermofuse Opens the fu sing lamp circuit if

the fusing unit overhe at s.

TH1 Fusing Thermistor Senses the temperat ure of the

hot roller.

117

119

1-22

23 April 1993 ELECTRICAL COMPONENT DESCRIPTION

Symbol Name Function Index

No.

TH2 Optics Thermistor Monitors the temperature of the

optics cavity.

TH3 Drum Thermistor

(Located on the ID

Monitors the tempe rature 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 of

114

copies made.

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

116 protection for the electrica l components.

Overall

Information

LA1 Lightening Arrestor Removes current surg es fro m the

AC input lines.

118

1-23

SECTION 2

DETAILED SECTION

DESCRIPTIONS

VL Pattern

Original

Toner Supply On time Development. Bias

TD Sensor

Image Density Control

23 April 1993 PROCESS CONTROL

1. PROCESS CONTROL

1.1 OVERVIEW

Original Scale

Image Density Control (Fuzzy Control)

Latent Image Control

ADS Pattern

VD Pattern

Latent image Control

Exposure Control

Charge Control

Temperature Sensor

Main PCB

Lamp Voltage

Grid Voltage

Paper

VD Pattern

ID Sensor

VL Pattern

Erase Lamp

Drum Potential Sensor

(Fuzzy Control)

Toner Supply Control

Exposure Glass

Detailed

Descriptions

This model uses two process control methods. One compensates for variation in the drum potential (latent image control) and the othe r con tro ls the toner concentratio n an d tone r supply a mou nt (image density control).

2-1

Erase

PROCESS CONTROL 23 April 1993

1.1.1 Latent Image Control

Charge

Exposure

Black White

Potential Sensor

Drum

The figure shows the changes of the drum pote nt ial du ring the copy process. Vo: The drum potential just afte r charg ing the drum. VD (Dark Potential): The drum potential just after exposing the black

pattern (VD pattern)

VL (Light Potential): The drum potential ju st af ter exposing the white

pattern (VL pattern)

VR (Residual Voltage ): The drum potential just after t he expo sure of the

erase lamp.

After long usage following installation or a PM, drum potentia l will gra dually increase due to the following factors:

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

In this copier, th e change in drum potential is detected by the drum potentia l sensor and the following it ems are cont rolle d to maint ain goo d cop y quality.

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

A drum thermistor detects the drum tempera ture an d this data is also use d to control the above voltages. It is impossible to explain simply because it is controlled by methods developed in our laboratories using an artificia l n eural network.

2-2

23 April 1993 PROCESS CONTROL

1.1.2 Image Density Control

Image density is controlled by the following sensors:

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

Data from the TD sensor is used to keep the toner con centration in the developer at a constant level. However, the image on the OPC drum varies due to the variation of toner charge ab ility (inf luenced by the environment) even if the toner concentration is constant. By the ID sensor compensation, toner concentratio n is change d to keep the ima ge den sity on the OPC dru m constant.

The following items are contro lled to main ta in a con sta nt copy imag e density:

Toner supply clutch on time

Detailed

Descriptions

Toner supply level data (VREF) of the TD sensor

2-3

PROCESS CONTROL 23 April 1993

1.2 PROCESS CONTROL DATA INITI AL SE TTI NG

The following flow chart shows all the steps that will be perf orme d whene ver the machine is turned on while the hot ro ller te mpe rature is below 100°C. This initializes all the process control sett ings.

Main SW On (Fusing Temp. < 100°C)

Charge wire cleaning (if more than 5 K copie s are mad e since last cleaning

Drum Potential Sensor Calibration

①

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

VSG Adjustment

VR Measurement

VD/VL Correction

TD Sensor Detection

②

ID Sensor Detection/Correctio n

③

ADS Adjustment

① : See Latent Image Control section (Page 2-5) for details. ② : See Image Density Control section (Pa ge 2-12 ) for deta ils. ③: See Optics section (Page 2-3 9) for details.

2-4

23 April 1993 PROCESS CONTROL

1.3 LATENT IMAGE CONTROL

1.3.1 Drum Potential Sensor Calibra tion

[A]

RA601

-100 V

RA602

-800 V

Drum

[B]

Case

Sensor

Output

Amp.

Detailed

Descriptions

Main PCB

The drum potential se nso r [ A] is located just above the development unit. The sensor has a detector which dete cts th e stre ngth of the ele ctric field from the electric potential on the drum. The output of the sensor depends on the strength of the electric field.

Since the output of the sensor is affected by environmental conditions, such as temperature and humidity, the sensor outp ut is calibrat ed durin g pro cess control data initial setting.

The High Voltage Contro l PCB [B] has two relay contacts. Usually RA 602 grounds the drum. However, during the initial setting, th e main PCB tu rns RA601 on and RA602 off an d ap plie s t he volta ge to th e drum shaft.

By measuring the output of the drum po te ntial sensor when –100 V and –800 V are applied to the drum, the sensor output is calibrated auto mat ically. (The machine recognize s t he re lat ionship between actua l drum po te ntial and the potent ial sensor output.)

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