Ricoh FT3113 Service manual

IMPORTANT SAFETY NOTICES

PREVENTION OF PHYS ICAL INJURY

1. Before disassembling or asse mblin g pa rts of the copie r and perip herals, make sure that the copier power cord is unplu gg ed.

2. The wall outlet should be near the copier an d easily accessible.

3. Note that some compo ne nt s of th e copier and the paper tray unit are supplied with electrical voltage even if the main switch is turned off.

4. If any adjustment or operat ion check has to be made with exterior covers off or open while the main switch is turned on, keep hands away from electrified or mechanically drive n comp on ents.

5. The inside and the met al parts of the fusing unit become extre mely ho t while the copier is operat ing . Be ca ref ul to avoid touching those components with your bare hands.

HEALTH SAFETY CONDITIONS

1. Never operate the copier without the ozon e filt er inst alle d.

2. Always replace the ozone filter with the specified one at the specifie d interval.

3. Toner and developer are non-toxic, but if you get either of them in your eyes by accident, it may cause temp ora ry e ye disco mfo rt. Try to remove with eye drops or flush with wat er as first aid. If un succe ssfu l, ge t med ical attention.

OBSERVANCE OF ELECTRICAL SAFETY STANDARDS

1. The copier and its peripheral must be installed and maintained by a customer service represen tative who has completed the training course on those models.

2. The RAM pack has a lithium battery which can explod e if hand led incorrectly, replace only with same RAM pack. Do not recharge, or burn this battery. Used RAM pack must be handle d in accordance with local regulations.

SAFETY AND ECOLOGICAL NOTES FOR DISP OS AL

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

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

3. Dispose of replaced parts in acco rda nce with local regulations.

SECTION 1

OVERALL MACHINE

INFORMATION

15 January 1992 SPECIFICATIONS

1. SPECIFICATIONS

Configuration : Desk top Copy Process: Dry electrostatic transfer system Originals: Sheet/Book Original Size: Maximum A3/11" x 17" – A077/A078 copiers

B4/10" x 14" – A076 copier

Copy Paper Size: Maximum – B4/10" x 14"

Minimum – A5 (lengthwise)/51/2" x 81/2"

Copy Paper Weight: Paper tray feed – 52 to 90 g/m2 (14 to 24 lb)

Manual feed – 52 to 157 g/m2 (14 to 42 lb)

Reproduction Ratios: 2 Enlargement and 3 Reduction

(A077/A078 copiers only)

A4 Version Letter Version

Enlargement

Full size 100% 100%

Reduction

Zoom: From 61% to 141% in 1% steps

(A077/A078 copiers only)

Copying Speed: 13 copies/minute (A4 leng th wise/81/2" x 11")

10 copies/minute (B4/10" x 14") Warm-Up Time: 30 seconds (at 20°C/68°F) First Copy Time: 9 seconds (A4 lengthwise/81/2" x 11") Copy Number Input: Quantity keys, 1 to 99 (count up) Manual Image Density

Selection:

7 steps

141% 122%

93% 82% 71%

129% 121%

93% 74% 65%

1-1

SPECIFICATIONS 15 January 1992

Automatic Reset: 1 minute standard setting; can also be set to 3

minutes or no auto reset. Automatic Start: When the Start key is pressed bef ore the copier

finishes the warm-up cycle, the copier starts

making copies as soon as the warm-up cycle is

completed. Paper Capacity: Paper tray – 250 sheets

Manual feed table – 1 sheet Toner Replenishment: Cartridge exchange (320 g/cartridge) Copy Tray Capacity: 100 sheets (B4/10" x 14" or smaller) Power Source: 110V / 60Hz/ 15 A (fo r Taiwan)

115V/ 60Hz/ 15A (for North America)

220~230V/ 50Hz/ 8A (for Europe)

220V/ 60Hz/ 8A (for Middle East)

240V/ 50Hz/ 8A (for Europe)

(Refer to the serial number plate (rating plat e) to

determine the power source required by the

machine.) Power Consumption:

Noise Emission:

Copier Only With DF Maximum 1.4 kVA 1.5 kVA Warm-up 0.60 kVA (average) 0.62 kVA (average) Copy cycle 0.81 kVA (average) 0.86 kVA (average) Stand-by 0.16 kVA (average) 0.18 kVA (average)

Copier Only With DF Maximum 58 db 60 db Warm-up Less than 40 db Less than 40 db Copy cycle Less than 55 db Less than 55 db

1-2

15 January 1992 SPECIFICATIONS

Dimensions:

Width Depth Height

Copier only

With DF

A076/A077

copiers A078 copier 830 mm (32.7") 582 mm (23.0") 503 mm (19.9") A077 copier 830 mm (32.7") 582 mm (23.0") 463 mm (18.3") A078 copier 830 mm (32.7") 582 mm (23.0") 563 mm (22.2")

830 mm (32.7") 582 mm (23.0") 403 mm (15.9")

Weight: Copier only – A076/A077 Copiers 43 kg (94.8 lb)

A078 Copier 51 kg (112.5 lb)

With DF – A077 Copier 50 kg (110.3 lb)

A078 Copier 58 kg (127.9 lb)

Optional Equipment: Document feeder

Key counter Drum anti-condensation heater Optics anti-condensation heater

• Specifications are subject to chan ge witho ut notice.

1-3

COPY PROCESSES AROUND THE DRUM 15 January 1992

2. COPY PROCESSES AROUND THE DRUM

2. EXPOSURE

1. DRUM CHARGE

3. ERASE

9. QUENCHING

4. DEVELOPMENT

8. CLEANING

7. PAPER SEPARATION

5. PRE-TRANSFER LAMP (PTL)

6. IMAGE TRANSFER

1-4

15 January 1992 COPY PROCESSES AROUND THE DRUM

1. DRUM CHARGE

In the dark, the charge corona unit gives a uniform negative charge to the organic photoconductive (OPC) drum. The charge remains on the surface of the drum because the OPC drum has a high electrical resistance in the dark.

2. EXPOSURE

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

3. ERASE

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

4. DEVELOPMENT

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

5. PRE-TRANSFER LAMP (PTL)

The PTL illuminates the drum to remove all negative charge from the exposed areas of the drum. This prevents the toner particles from being reattracted to the drum surface during paper separation and makes paper separation easier.

6. IMAGE TRANSFER

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

7. PAPER SEPARATION

A strong ac corona discharge is applied to the back side of the copy paper, reducing the negative charge on the copy paper and breaking the electrical attraction between the paper and the drum. Then, the stiffness of the copy paper causes it to separate from the drum surface. The pick-off pawls help to separate paper.

8. CLEANING

The cleaning brush removes most of the toner on the drum and loosens the remainder. Then the cleaning blade scrapes off the loosened toner.

9. QUENCHING

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

1-5

COPY PROCESS CONTROL 15 January 1992

3. COPY PROCESS CONTROL

Image Density Control

Toner Density Detection

Residual Voltage (Vr) Detection

Between Copies

Grid Voltage

1. Manual image density mode

Standard ima ge density grid voltage

+ + Manual image density

level fact or + Drum residual voltage (Vr) correction factor + Drum temperature correction factor

2. Auto imag e density mode

Standard ima ge density grid voltage +

Auto image density level factor (SP34 )

+ Drum residual voltage (Vr) correction factor + Drum temperature correction factor

Standar d I D sensor gri d voltage +

Drum wear correction factor (SP57)

Standar d I D sensor gri d voltage + Drum wear correction factor (SP57)

0 volts (Fix ed) Ex p osure lamp turns

Exposure Lamp

Voltage

Base exposure lamp voltage (Manual or

ADS mode) (SP48)

Reproduct ion ratio correction factor (A077/A078 copiers only) + Drum temperature correction factor + Drum residual voltage (Vr) correction factor

Same as image density co ntrol

off.

Developmen t Bia s

Voltage

Base bias voltage factor (Manual or

ADS mode [SP34])

Image bias voltage adjustment factor (SP37)

+ Drum residual voltage (Vr) correction factor + Drum temperature correction factor

Note: Base bias voltage at manual ID level 7 can be adjusted by SP50.

Depends on ID sensor b ias settin g (SP33)

Note: For initial 499 copies bias volt age is increased by –20 volts.

0 volts (Fixed) Full erase

–160 volt s (F ixed) +

Base bias voltage adjustment factor (SP37)

+ Drum residual voltage (Vr) correction factor + Drum temperature correction factor

Erase Lamp

Depends on paper size and reproducti on ratio.

ID sensor pattern eras e (Vsg detectio n: Full erase)

(All LEDs ON)

Full erase (All LEDs ON)

NOTE: The boxed item can be adjusted by SP mode.

1-6

15 January 1992 MECHANICAL COMPONENT LAYOUT

4. MECHANICAL COMPONENT LAYOUT

20 21 22

23 24 25

26 27

31 32

34 35

36 37

38 39

1. 1st Semicircular Pick-up rollers

2. 1st Paper Tray

3. Registration Rollers

4. Pre-transfer Lamp (PTL)

5. Transfer and Separation Corona Unit

6. Pick-off Pawls

7. Cleaning Unit

8. Pressure Roller

9. Fusing Unit

10. Hot Roller

11. Exit Rollers

12. Copy Tray

13. Hot Roller Strippers

14. Exhaust Blower Motor

15. 3rd Mirror

16. 2nd Mirror

17. 1st Mirror

18. Ozone Filter

19. Used Toner Tank

20. Cleaning Brush

21. Cleaning Blade

22. Quenching Lamp

23. Charge Corona Unit

24. Lens

25. 6th Mirror

26. Erase Lamp

27. Drum

28. 4th Mirror

29. 5th Mirror

30. Optics Cooling Fan

31. Developer Tank

32. Toner Supply Unit

123456

33. Development Unit

34. Manual Feed Roller

35. 1st Relay Rollers

36. Manual Feed Table

37. 2nd Relay Rollers

38. 1st Paper Feed Roller

39. 1st Torque Roller

40. 2nd Feed Relay Rollers (A078 copier only)

41. 2nd Torque Roller (A078 copier only)

42. 2nd Paper Feed Roller (A078 copier only)

43. 2nd Semicircular Pick-up Rollers (A078 copier only)

44. 2nd Paper Tray (A078 copier only)

424344

1-7

ELECTRICAL COMPONENT LAYOUT 15 January 1992

5. ELECTRICAL COMPONENT LAYOUT

13 12

1. 1st Paper Tray Switch

2. Relay Sensor

3. Registration Clutch

4. Registration Sensor

5. Optics Cooling Fan Motor

6. Image Density Sensor (with drum thermistor)

7. Power Pack-TC/SC

8. Operation Panel Board

9. Erase Lamp

10. Total Counter

11. Quenching Lamp

12. Fusing Lamp

13. Front Cover Safety Switch

14. Main Switch

15. Fusing Thermoswitch

16. Exit Sensor

17. Exhaust Blower Motor

18. Optics Thermofuse

19. Auto Image Density Sensor

20. Fusing Thermistor

21. Pre-transfer Lamp

22. Exposure Lamp

23. Lens Motor (A077/A078 copiers only)

24. Scanner Home Position Sensor

25. DF Interface Board (A077/A078 copiers only)

26. Lens Home Position Sensor (A077/A078 copiers only)

27. Power Pack-CC/Grid/Bias

28. AC Drive Board

29. Fusing Triac (115 V only)

30. Scanner Motor

31. Drum Motor Board

37 38

32. Drum Motor

33. 4th/5th Mirror Home Position Sensor (A077/A078 copiers only)

34. 4th/5th Mirror Motor (A077/A078 copiers only)

35. Main Motor Capacitor

36. Key Counter (Option)

37. Main Board

38. Development Clutch Solenoid

39. Main Motor

40. Toner Supply Clutch

41. DC Power Supply Board

42. Relay Roller Clutch

43. 1st Paper Feed Clutch

44. 2nd Paper Feed Clutch (A078 copier only)

45. 2nd Paper Tray Switch (A078 copier only)

1-8

15 January 1992 ELECTRICAL COMPONENT DESCRIPTIONS

6. ELECTRICAL COMPONENT DESCRIPTIONS

Motors

SYMBOL NAME FUNCTION

Drives all the main unit components except for the

M1 Main Motor

M2 Scanner Motor Drives the scanners (1st and 2nd). (dc stepper) 30

M3 Lens Motor

M7 Drum Motor Drives the drum. (dc servo) 32

4th/5th Mirror Motor

Optics Cooling Fan Motor

Exhaust Blower Motor

optics unit, drum unit and fans. (115/220–230/240 Vac [ac synchronous])

Moves the lens position according to the selected magnification. (dc stepper) … A077/A078 copiers only

Positions the 4th/5th mirrors according to the selected magnification. (dc stepper) … A077/A078 copiers only

Prevents built up of hot air in the optics cavity. (24 Vdc)

Removes heat from around the fusing unit and moves the ozone built up around the charge section to the ozone filter. (115/220–230/240 Vac)

INDEX

NO.

Magnetic Clutch

SYMBOL NAME FUNCTION

MC1

Registration Clutch

Drives the registration rollers. 3

Magnetic Spring Clutches

SYMBOL NAME FUNCTION

MSC1

MSC2

MSC3

MSC4

Toner Supply Clutch

Relay Roller Clutch

1st Paper Feed Clutch

2nd Paper Feed Clutch

Drives the toner supply roller. 40

Drives the 1st and 2nd relay rollers. 42

Starts paper feed from the 1st paper feed station. 43 Starts paper feed from the 2nd paper feed station.

… A078 copier only

Solenoid

SYMBOL NAME FUNCTION

SOL1

Development Clutch Solenoid

Transmits the main motor drive to the development drive gears.

INDEX

NO.

INDEX

NO.

INDEX

NO.

1-9

ELECTRICAL COMPONENT DESCRIPTIONS 15 January 1992

Switches

SYMBOL NAME FUNCTION

SW1 Main Switch Supplies power to the copier. 14 SW2

SW3

SW4

Front Cover Safety Switch

1st Paper Tray Switch

2nd Paper Tray Switch

Cuts the ac power line, when the front cover is open.

Detects when the 1st paper tray is set. 1 Detects when the 2nd paper tray is set.

… A078 copier only

INDEX

NO.

Sensors

SYMBOL NAME FUNCTION

S4 S5 Exit Sensor Detects misfeeds. 16

S6 Relay Sensor

Scanner Home Position Sensor

Lens Home Position Sensor

4th/5th Mirror Home Position Sensor

Registration Sensor

Image Density (ID) Sensor

Auto Image Density Sensor (ADS)

Informs the CPU when the 1st scanner is at the home position.

Informs the CPU when the lens is at the home position (full size position). … A077/A078 copiers only

Informs the CPU when 4th/5th mirrors assembly is at the home position (full size position). … A077/A078 copiers only

1) Detects misfeeds.

2) Controls the relay roller clutch stop timing.

1) Detects when the copy paper is set in the manual feed table.

2) Detects misfeeds. Detects the density of the image on the drum to

control the toner density.

Senses the background density of the original. 19

INDEX

NO.

Printed Circuit Boards

SYMBOL NAME FUNCTION

PCB1 Main Board

PCB2 AC Drive Board

PCB3

PCB4

PCB5

DC Power Supply Board

DF Interface Board

Operation Panel Board

Controls all copier functions both directly and through the other PCBs.

Drives all ac motors, the exposure lamp, fusing lamp, quenching lamp, exhaust blower motor.

1) Steps down the wall voltage to 28 Vac.

2) Rectifies 28Vac input and outputs dc voltages. (30 volts, 24 volts, 5 volts)

Interfaces between the copier main board and DF. … A077/A078 copiers only

Informs the CPU of the selected modes and displays the situations on the panel.

1-10

INDEX

NO.

15 January 1992 ELECTRICAL COMPONENT DESCRIPTIONS

SYMBOL NAME FUNCTION

PCB6

Drum Motor Board

Controls the drum motor speed. 31

Lamps

SYMBOL NAME FUNCTION

L1 Exposure Lamp L2 Fusing Lamp Provides heat to the hot roller. 12 L3 Quenching Lamp

L4 Erase Lamp

Pre-transfer Lamp

Applies high intensity light to the original for exposure.

Neutralizes any charge remaining on the drum surface after cleaning.

Discharge the drum outside of the image area. Provides leading/trailing edge and side erases.

Reduces charge on the drum surface before transfer.

Power Packs

SYMBOL NAME FUNCTION

Power Pack –CC/Grid/Bias

Power Pack –TC/SC

Provides high voltage for the charge corona, grid, and the development roller bias.

Provides high voltage for the transfer and separation corona.

INDEX

NO.

INDEX

NO.

INDEX

NO.

Heaters

SYMBOL NAME FUNCTION

Drum Anticondensation Heater (Option)

Optics Anticondensation Heater (Option)

Prevents moisture around the drum. When the main switch is turned on (off) the heater turns off (on).

Prevents moisture from forming on the optics. When the main switch is turned on (off) the heater turns off (on).

Counters

SYMBOL NAME FUNCTION

CO1 Total Counter Keeps track of the total number of copies made. 10 CO2

Key Counter (Option)

Used for control of authorized use. Copier will not operate until installed.

1-11

INDEX

NO.

N/A

INDEX

NO.

ELECTRICAL COMPONENT DESCRIPTIONS 15 January 1992

Others

SYMBOL NAME FUNCTION

TH1 TH2 Drum Thermistor Monitors the temperature around the drum. 6

TR Fusing Triac

Fusing Thermistor

Fusing Thermoswitch

Optics Thermofuse

Main Motor Capacitor

Monitors the fusing temperature. 20

Provides back-up overheat protection in the fusing unit.

Provides back-up overheat protection around the exposure lamp.

Start capacitor. 35 Switches the fusing lamp on and off. (115 V only)

Note: In the 220V-230V/240V version, the triac

is built-in the ac drive board

INDEX

NO.

1-12

G23

G27

G29

G28: Relay Gear

15 January 1992 DRIVE LAYOUT

7. DRIVE LAYOUT

G22

TB2 G21 G20 G19

G18 G17 G16

G15 G14

G13 G12

G11

G24

G10

G25

TB3 BP6G26BP5BP4BP3

G28

G30 G31

G32

G33

G34

G1: Main Motor Gear

G2: Timing Belt Drive Gear

BP1: Timing Belt Pulley

TB1: Timing Belt

G26 Relay gear

G25: Timing Belt Drive Gear

BP4: Timing Belt Pulley

TB2: Timing Belt

Development Section

BP3: Timing Belt Pulley

G24: Development CL Gear

Development CL

BP2

TB1 BP1

G34: Relay Gear

G27: Cleaning Drive Gear

Cleaning Unit

G33: Fusing Drive Gear

Fusing and Exit Unit

G29: Hot Roller Gear

G30: Relay Gear

G31: Relay Gear

G32: Exit Roller Gear

Development Unit

G23: Relay Gear

G22: Toner Supply CL Gear

Toner Supply CL

1-13

Toner Supply Unit

G14: Relay Gear

G13: Relay Gear

G12: Relay Gear

G8: Relay Gear

2nd Torque Roller

G10: Relay Gear

DRIVE LAYOUT 15 January 1992

Paper Feed Section

BP2: Timing Belt Pulley

G3: Registration CL Gear

Registration CL

Registration Rollers

G21: Relay Gear

G20: Relay Roller CL Gear

Relay Roller CL

2nd Relay Rollers G19: Relay Gear

G18: 1st Relay Roller Gear

1st Relay Rollers

G4: Relay Gear

1st Paper Feed Section

G5: 1st Paper Feed CL Gear

1st Paper Feed CL

1st Pick-up Rollers G17: 1st Pick-up Roller Gear

G15: Relay Gear

G16: 1st Paper Feed Roller Gear

1st Paper Feed Roller

1st Torque Roller

2nd Paper Feed Section

G6: 2nd Paper Feed CL Gear

2nd Paper Feed CL

2nd Pick-up Rollers G7: 2nd Pick-up Roller Gear

BP6: Drum Motor Pulley

TB3: Timing Belt

BP5: Drum Drive Pulley

Drum

G9: 2nd Paper Feed Roller Gear

2nd Paper Feed Roller

G11: 2nd Feed Relay Roller Gear

2nd Feed Relay Rollers

1-14

15 January 1992 POWER DISTRIBUTION

8. POWER DISTRIBUTION

AC Power (115V or 220~230V/240V)

Exhaust Blower Motor (L)

Fusing Lamp

Exposure Lamp

Main Motor Quenching Lamp Exhaust Blower Motor (H)

Document Feeder

(Option)

Drum Motor Board (Drum Motor)

24V (VA)

Main SW

Cover Safety SW

Power Relay

(RA401)

Fusing Lamp Drive Circuit

Exposure Lamp Drive Circuit

Main Motor

Relay (RA402)

AC Drive Board

DC Power Supply Board

24V (VA)

30V (VM) 24V (VA)

5V (VC) Zero Cross

RAM Pack

Main

Board

Anti-condensation Heaters

-Drum (Option)

-Optics (Option)

Scan Signal

5V (VC)

24V (VA)

30V (VM)

9V (VB)

Operation Panel Board Sensors

Switches Drum Motor Board (Encoder)

DF Interface Board (A077/A078 copiers only)

Thermistors Solenoids

Clutches Power Packs Lens Motor (A077/A078 copiers only)

4th/5th Mirror Motor (A078 copier only)

Optics Cooling Fan Motors

Image Density Sensor

Scanner Motor

AC power DC power

When this copier is plugged in and the main switch is turned off , ac power is supplied via the ac drive board to the anti-condensation heate rs. Whe n the front cover and/or the exit cove r is open, the cover safety switch complete ly cuts off power to all ac and dc components. The RAM pack has a back up power supply (dc battery) for the service program mode data and misfee d job recovery.

When the main switch is turned on, the ac power sup ply to the anti-condensation heat er is cut of f an d ac power is supp lied to the ac drive board. The dc power supply board receives wall outlet ac power through the ac drive board.

The dc power supply board converts th e wall outle t ac po wer inp ut to +5 volts, +24 volts, +30 volts and a zero cro ss signal.

1-15

POWER DISTRIBUTION 15 January 1992

The +24 volts is supplied to both the main board and the drum motor board. The +5 volts, +30 volts and th e zero cross sig na l are sup plied to the main board.

The main board supplies dc p owe r to all copier dc components except for th e drum motor. All sensors (except for the ID sensor), switches, thermisto rs, th e drum motor encoder, plus the DF interface board operate on +5 volts. The image density sensor as well as the operatio n pane l operates on +9 volts, supplied by the main board. The scann er mot or op era te s on +30 volts. All other dc components including the power relay (RA401) and th e main motor relay (RA402) operate on +2 4 volt s. The document feeder has a separate dc power supply.

When the main board receives power, it act ivat es the power rela y (RA 401) which then supplies ac power to the fusin g lamp drive circuit, and the exposure lamp drive circuit on the ac drive board. The exhaust blower motor begins rotating at low speed. The fusing lamp drive circuit receives a trigger signal from the main board an d the fusing lamp lights. The exp osure lamp does not turn on until the main boa rd send a trigger pulse to the exp osu re lamp drive circuit.

When the Start key is pressed, the main bo ard ene rgize s the main mot or relay (RA402). Then, the main motor and the quenching lamp turn on an d th e exhaust blower starts rotating at high speed.

When the main switch is turned off, power is cut off to the main board and to RA401, and the optional drum and optics anti-condensation heaters are turned on.

1-16

SECTION 2

DETAILED SECTION

DESCRIPTIONS

15 January 1992 DRUM

1. DRUM

1.1 DRUM CHARACTERISTICS

The drum has the characteristics o f:

1. Being able to accept a high negative electrical charge in the dark. (Th e electrical resistance of a photocon ductor is high in the absence of light.)

2. Dissipating the electrical charge when exposed to light. (Exposure to light greatly increases the conduct ivity of a photo con du cto r.)

3. Dissipating an amount of charge in dire ct pro po rtio n to the inte nsity of the light. That is, where stronger light is directed to the photoconductor surface, a smaller voltage remains on the drum.

4. Under low temperatures, drum photose nsit ivity dro ps an d residua l volta ge increases. This makes it necessary t o monitor the drum temperature and some compensation is require d.

5. During the drum’s life, drum residu al volt ag e gra du ally increases and the photoconductive surface becomes worn. Therefore, some compen sat ion for these characteristics is required.

2-1

DRUM 15 January 1992

1.2 DRUM UNIT

[F]

[E]

[B]

[G]

[A]

[C]

[D]

An organic photoconductor (OPC) dru m [A] is used in this mode l. A drum unit [B] holds the drum and preve nts stress on the drum. The drum

unit consists of an OPC drum, ID sensor bo ard [C] an d pick-o ff pawls [D] . When the drum, the pick-off pawls, or the ID sensor is replaced or clean ed, the drum unit must be removed from the copier.

The drum is driven by an independent drum motor [E] thro ugh a timing belt [F] and the drum drive pulley [G].

The pick-off pawls are always in contact with the drum surface. The ID sensor board consists of the ID sen sor and th e dru m the rmisto r.

2-2

Drum Motor (M7)

15 January 1992 DRUM

1.3 DRUM MOTOR CONTROL

Main Board (PCB 1)

VC [5]

ON signal [▼5]

GND [0]

DC Power Supply Board (PCB 1)

VA [24]

GND [0]

CN131-3 CN131-2

CN131-1

CN204-3 CN204-1

CN801-1 CN801-2 CN801-3

CN802-3 CN802-1

▼24]

[

24 V

5 V

GND [0]

Drum Motor Board (PCB 1)

CN803-1 CN803-2

CN804-3 CN804-2 CN804-1

Encoder

The drum motor is a dc servomotor. The drum motor board controls the speed of this servomotor.

When the Start key is pressed, the main bo ard send s an "ON sig nal" to the drum motor board (CN131-2) to energize the drum motor.

The encoder on the servomotor has a phot oin te rrupter that generates a series of pulse signals. The drum mot or board monitors these pulse signals to regulate the motor speed (10 0 mm/se con d).

2-3

DRUM CHARGE 15 January 1992

2. DRUM CHARGE

2.1 OVERVIEW

[A]

[B]

[D]

[A]

This copier uses a double wire scorotro n and a highly sensitive OPC drum [A]. The corona wires [B] ge ne rat e a corona of negative ions when the CC/Grid/Bias power pack [C] applies a high voltage. The CC/Grid/Bias power pack also applies a negative high volta ge to a stainless steel grid plate [D]. This insures that the drum coating receives a uniform negative charg e as it rotates pa st the corona unit.

[C]

[D]

The exhaust fan, located abo ve the cop y exit, causes a flow of air from the upper area of the deve lop ment unit through the charg e coro na unit . This prevents an uneven bu ild-u p of negative ions that can cause uneven image density. The exhaust fan runs at half spe ed when in the st and-by condition and at full speed while copying.

The exhaust fan has an ozo ne filte r (a ctive ca rbo n) which adsorbs ozone (O3) generated by the coro na charge. The ozone filter decre ases in efficiency over time as it adsorbs ozone. The ozone filter should be replaced at every 80000 copies.

The flow of air around the charge corona wires may deposit paper dust or toner particles on the corona wire . The se pa rticle s may interfere with charging and cause low density ba nd s on cop ies. The wire clea ne r clean s the corona wire when the op era to r slides the corona unit out and in.

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15 January 1992 DRUM CHARGE

2.2 CHARGE CORONA WIRE CLEANE R MECHANI S M

[B]

[A]

[D]

[C]

Pads [A] above and below th e charge corona wires clean the wires as th e charge unit is manually slid in and out.

The cleaner pad bracket [B ] rotates when the charge unit is fully e xte nd ed and the bracket is pulled up against the rear en dblock [C]. This moves the pads against the corona wires (see illustra tion). If the charge unit is not fu lly extended, the pads do not tou ch th e corona wires.

The pads move away from the wires when the charg e unit is f ully inse rted and the cleaning bracket is pushed against the front endblock [D].

After copier installa tio n the key operator should be instru cted to use this mechanism when copies exhibit low ima ge den sity band s.

2-5

Power Pack CC/Grid/Bias (P1)

Charge Corona

Development Bias

DRUM CHARGE 15 January 1992

2.3 CHARGE CORONA CIRCUIT

VA [24]

VC [5]

CC Trig [▼24]

Grid Trig (PWM) [▲0→0/5]

Grid FB

GND [0]

Main Board (PCB 1)

1350

Timing Pulse

(1pulse=4msec)

Start Key

Charge Corona and Grid Voltage

200

CN119-8 CN119-7 CN119-6 CN119-5 CN119-4 CN119-3 CN119-2 CN119-1

1500

1589 1782

Toner Density Detection Cycle

CN1-1 CN1-2 CN1-3 CN1-4 CN1-5 CN1-6 CN1-7 CN1-8

2000 2500 3000

Image Area

Grid

(Pulse)

The main board supplies +24 volt s to th e CC/G rid/Bias power pack at CN1-1 as the power supply source. About 2.5 seconds after th e Start key is pressed (during the toner d en sity detection cycle about 1.8 second s), th e CPU drops CN1-3 from +24 volts to 0 volts. This energizes the charge coron a circuit within the CC/Grid/Bias power pack, which applies a high nega tive volta ge of approximately –7.0 K volts to th e cha rge corona wires. The corona wires then generate a negative corona charge.

The grid plate limits the cha rge voltage to ensure that the charge does not fluctuate and that an even charge is applied to the drum surfa ce.

The grid trigger pulse applied to CN1-5 is a pulse width modulated signal (PWM signal). This signal is not only a trigger signal, it also chan ges the voltage level of the grid. As the width of the pulse ap plie d incre ases, the voltage of the grid also incre ases. The CPU monitors the grid volta ge at CN119-2 and controls the width of the grid trigger pulses based on th is feedback.

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15 January 1992 DRUM CHARGE

2.4 GRID VOLTAGE CORRECTION

To maintain good copy quality ove r the drum’s life , th e grid volta ge is changed by the following:

• Drum residual voltage correction (Vr correction)

• Drum temperature correction

• Drum wear correction

2.4.1 Drum Resi dual Volta ge Corr ec tion (Vr corr ection)

During the drum’s life, the dru m may fat igu e electrically and residual voltage (Vr) on the drum may gradually increase. When this happens, the corona charged voltage on th e dru m is not disch arged enough in the quenching an d exposure processes. Even if the development bia s is applie d in th e development process, the background area of th e orig inal on the drum may attract some toner. This may cause dirty background on copies. The Vr correction prevents this ph enomenon as follows:

A pattern (Vr pattern) is develope d on the drum eve ry 100 0 cop ies and its reflectivity is detected by the ID sen sor to measu re th e resid ua l volta ge . This is called residual voltage detect ion . (If the reflectivity is low, the residual voltage will be high.) When the Vr pattern is developed, all blocks of the erase lamp turn on, and th e de velo pment bias voltage is 0 volt.

The CPU determines what level of Vr co rrect ion is necessa ry dep en din g on the output (Vr ratio [L]) from the ID sensor.

Vrp

L =

x 100 (%)

Vsg

Vrp: ID sensor outp ut for Vr pattern

Vsg: ID sensor output for bare drum The current Vr ratio is disp laye d by SP67. The CPU increases the development bias voltage depending on the Vr ratio

to prevent dirty backgrou nd on copies, (See page 2-33 for more informatio n. ) The CPU also increases the grid volta ge to ensure prop er imag e de nsit y depending on the Vr ratio. (See page 2-11.)

Because the grid voltag e is increased, the charge volta ge on th e dru m ’s surface is also increased. To compe nsate for the charge voltage increase, the exposure lamp voltage is also incre ased. (See page 2-21.)

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DRUM CHARGE 15 January 1992

2.4.2 Drum Temperature Correction

During a low drum temperature condition, the drum’s residual voltage increases and drum photosen sitivity drops due to the characterist ics of th e drum. This may cause dirty background on copies. A drum temperature correct ion is made to compe nsa te for th is phe nomenon as follows:

A drum thermistor on the ID sensor board mon itors the temperature around the drum. When the drum temperature is less than 20°C, the CPU increases the development bia s vo lta ge to pre vent dirty background on copies. (S ee page 2-33.) The CPU also increases th e grid voltage to ensure proper image density. (See page 2-11.) The exp osu re lamp voltage is also increased to compensate for the drum p hoto sensitivity drop. (See page 2-20.) Whe n the drum temperature is 20°C or higher, the drum te mpe rat ure correct ion is not made.

2.4.3 Drum Wear Correction

During the drum’s life, the photoco nd uct ive surf ace of the drum becomes worn by contact with the cleaning brush. This effects ability of the drum to hold a charge. This characte ristic esp ecially affects developing of th e ID sensor pattern. The ID sensor pattern developed on th e dru m b eco mes lighter causing high er to ne r co nce ntration in the developer. The drum wear correction is made to prevent this phenomenon and is as follows:

The CPU keeps track of the drum motor ro ta tio n time that corre sponds to the wear of the photoconductive layer. The grid voltage for the toner density detection increases at set int erval. The grid voltage for the residu al volt ag e (Vr) detection also increase s at th e same interval. (See page 2-12.) The dru m motor rotation time is displayed by SP57.

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15 January 1992 DRUM CHARGE

2.5 GRID VOLTAGE FOR IMAGE DENSITY CONTROL

The main board controls the grid volt age fo r a copy imag e th rou gh the CC/Grid/Bias power pack. As the grid volta ge beco mes less, the copy imag e becomes lighter and vice versa. The grid voltage is based on the stand ard image grid voltage (Vg) and various correction fact ors.

The method of control is different dependin g on whethe r the ima ge density is manually selected, or the auto imag e de nsit y mode is used.

The grid voltage for non-image areas (betwee n cop ies) is 0 volt (Fixed ). The grid voltage while cop ying consists of the following facto rs:

1. Manual image density mode

Grid voltage = Standard image density grid voltage

(Vg = –680 volts [SP60=4])

Manual image density level factor

Drum residual voltage (Vr) correction factor

Drum temperature correction factor

2. Auto image density mode

Grid voltage = Standard image density grid voltage

(Vg = –680 volts [SP60=4])

Auto image density level fact or (SP 34 )

Drum residual voltage (Vr) correction factor

Drum temperature correction factor

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DRUM CHARGE 15 January 1992

2.5.1 Manua l Image Density Level Factor

Darker Lighter

Manual ID level 1 2 3 4 5 6 7

Change of grid voltage (volts) ±0 ±0 ±0 ±0 ±0 +50 +50

The grid voltage does not change for manual image density levels 1 through

5. However, the exposure lamp volt ag e an d th e de velo pme nt bias volt ag e does vary depending on the manual imag e de nsit y le vel. (See page 2-1 9 and 2-31.)

The grid voltage at the manual image density level 6 is the same as the one at level 7, however, the exp osure lamp voltage and the deve lop ment bias voltage are different. (See page 2-19 and 2-31.)

2.5.2 Auto Ima ge Dens ity Level Factor (SP34)

Auto image density level Data (SP34) Change of grid voltage (volts)

Normal 0 ±0

Darker 1 –50 Lighter 2 ±0

The grid voltage and the expo sure la mp volt ag e are co nst an t reg ardless of the output from the auto image de nsit y senso r. Only the development bias voltage varies depending on the output from the auto image density sen sor.

When the auto image densit y le vel data is set to lighter, the chang e of the grid voltage is 0 volt. However, th e de velo pme nt bias volt ag e is chan ged –4 0 volts.

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