Ricoh FT8982, FT680 Service Manual FT8982

IMPORTANT SAFETY NOTICES

PREVENTION OF PHYSICAL INJ URY

1. While the machine warms up, it will suddenly start turning to perform the process control data initializa tio n. Keep hands away from any mechanical and electrical components during this perio d.

2. Before disassembling or assembling parts of the copier and periph erals, make sure that the copie r and the secon d sorter power cord is unplugged.

3. The wall outlet should be near the copie r and easily acce ssible .

4. Note that some comp onen ts of the copier, the paper tray un it, and the 2nd sorter are supplied with electrical volta ge even if the main switch is turned off.

5. If any adjustment or operation check has to be made with exte rior cove rs off or open while the main switch is turned on, keep hands away from electrified or mechanically driven components.

6. The inside and the meta l pa rt s of the fusing unit become ext reme ly hot while the copier is operating. Be careful to avoid touch ing tho se components with your bare hands.

HEALTH SAFETY CONDITIONS

1. Never operate the copier without the ozone filte rs in sta lled.

2. Always replace the ozo ne filte rs wit h th e specified ones at the specified intervals.

3. Toner and developer a re non-toxic, but if you get either of them in your eyes by accident, it may cause tempo rary eye discomf ort. Try to remove with eye drops or flush with water as f irst aid . If unsu ccessful, get medical attention .

OBSERVANCE OF ELECTRICAL SAFETY S TANDARDS

1. The copier and its peripherals must be inst alle d and main ta ine d by a customer service represent at ive who has completed the training course on those models.

2. The RAM board on the main contro l board ha s a lithium battery which can explode if replaced incorrectly. Replace the battery only with an ide nt ical one. The manufacture r recomme nd s replacing the entire RAM board. Do not recharge or burn this battery. Used batteries must be handled in accordance with local regulations.

SAFETY AND ECOLOGICAL NOTES FOR DI S POSAL

1. Do not incinerate the ton er cartridge or the used tone r. Ton er du st may ignite suddenly when exposed to open flame.

2. Dispose of used toner, developer, and photoconductors according to local regulations.

3. Dispose of replaced part s in accord an ce with local regulations.

4. When keeping used lithium batteries in order to disp ose of them later, do not put more than 100 batteries per sealed box. Storing larger numb ers or not sealing them apart may lead to chemica l re act ions and heat build-up.

SECTION 1

OVERALL MACHINE

INFORMATION

31 July 1995 SPECIFICATIONS

1. SPECIFICATIONS

Main Copier

Copier

Configuration: Console Copy Process: Dry Electrostatic Transfer S yste m Originals: Sheet/Book Original Size: Maximum:

11" x 17", A3 420 x 700 mm (in moving-original scan mode, Europe version only)

Copy Paper Size: Maximum:

1st and 2nd tray 11" x 17", A3 3rd tray 81/2" x 14", B4 By-pass table in moving-original scan mode (Europe version only) 420 x 700 mm

Minimum:

Tray 51/2" x 81/2", A5 By-pass table in moving-original scan mode (Europe version only) A5

Copy Paper Weight: Standard Copying: 14 ~ 42 lb, 52 ~ 157 g/m

Duplex Copying: 17 ~ 28 lb, 64 ~ 105 g/m Tab Sheets: 90 lb index, 160 g/m

Warm Up Time: Within 8.0 minutes (room temp. 68°F, 20°C) First Copy Time: 3.8 seconds (81/2" x 11", A4, copier only)

6.9 seconds (81/2" x 11", A4, with sorter stapler)

Copying Speed: 80 copies/minute (81/2" x 11")

82 copies/ minute (A4 )

Optional Equipment: 20 Bin Sorter 1 (A591)

20 Bin Sorter 2 (A591) Large Capacity Tray (A592) Key Counter Bracket Set (A59 8 - 00) Key Counter (Procured loca lly) Key Counter Holder (Procured loca lly) Receiving Tray (spare part) Guidance ROM Kit (A603)

2 2

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SPECIFICATIONS 31 July 1995

Reproduction Ratios: See the following table:

LT/DLT version A4/A3 version

200% 200%

Enlargement

Full Size 100% 100%

Reduction

155% 141% 129% 122% 121% 115%

93% 93% 77% 82% 74% 71% 65% 65% 50% 50%

Zoom: 50 ~ 200% Copy Exit Tray Capacity: 250 Sheets Toner Replenishment : Cartridge exchange (15 00 g) Paper Feed: 1st tray (500 sheets)

2nd tray (500 sheets) 3rd tray (1,700 Sheets) By-pass tray (40 sheets) (Europ ea n versio n)

Power Source: 240 V, 20 A or more (LT/DLT version)

220, 230, 240 V, 13 A or more (A4 /A 3 version)

Power Consumption:

LT/DLT version

Copier only Full system*

Warm up less than 2.10 kW less than 2.15 kW Stand-by less than 0.50 kW less than 0.55 kW

Copying less than 2.50 kW less than 2.60 kW

Maximum less than 2.60 kW less than 2.70 kW

* Full system: Copier with document feeder, large capacity tray, and a sorter stapler.

A4/A3 version (at 230 V)

Copier only Full system*

Warm up less than 2.0 kW less than 2.05 kW Stand-by less than 0.55 kW less than 0.6 kW

Copying less than 2.4 kW less than 2.5 kW

Maximum less than 2.5 kW less than 2.6 kW

* Full system: Copier with document feeder, large capacity tray, and a sorter stapler.

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31 July 1995 SPECIFICATIONS

Dimensions:

LT/DLT version

Width Depth Height

Copier with document feeder and copy tray 1,375 mm

54.2"

Copier with document feeder and one sorter stapler

Copier with document feeder, large capacity tray, and one sorter stapler

Copier with document feeder, large capacity tray, and two sorter staplers

1,625 mm

64.0"

2,070 mm

81.5"

2,610 mm

102.8"

760 mm

30.0"

873 mm

34.4"

873 mm

34.4"

873 mm

34.4"

1,445 mm

56.9"

1,445 mm

56.9"

1,445 mm

56.9’

1,445 mm

56.9’

A4/A3 version

Width Depth Height

Copier with document feeder and copy tray 1,438 mm

56.7"

Copier with document feeder and one sorter stapler

Copier with document feeder, large capacity tray, and one sorter stapler

Copier with document feeder, large capacity tray, and two sorter staplers

1,688 mm

66.5"

2,070 mm

81.5"

2,610 mm

102.8"

760 mm

30.0"

873 mm

34.4"

873 mm

34.4"

873 mm

34.4"

1,445 mm

56.9"

1,445 mm

56.9"

1,445 mm

56.9"

1,445 mm

56.9"

Weight:

Copier with document feeder 367 kg

Copier with document feeder and one sorter stapler

Copier with document feeder, large capacity tray, and one sorter stapler

Copier with document feeder, large capacity tray, and two sorter staplers

LT\DLT version A4\A3 version

377 kg

809.1 lb 465 kg

1025.2 lb 506 kg

1115.6 lb 596 kg

1314. 0 lb

831.2 lb 475 kg

1047.2 lb 516 kg

1137.6 lb 616 kg

1358.1 lb

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SPECIFICATIONS 31 July 1995

Noise Emission:

Sound pressure level

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

Copier only Full system*

Stand-by less than 42 dB (A) less than 42 dB (A)

Copying

* Full system: Copier with document feeder, large capacity tray, and a sorter stapler.

less than 63 dB (A)

(average)

less than 64 dB (A)

(average)

Sound power level (The measurements are made according to ISO 7779.)

Copier only Full system*

Stand-by less than 58 dB (A) less than 62 dB (A)

Copying less than 74 dB (A) less than 78 dB (A)

* Full system: Copier with document feeder, large capacity tray, and a sorter stapler.

Document Feeder

Original Size:

Stack feed

mode

Maximum 11" x 17", A3 11" x 17", A3 11" x 17", A3 A2

Minimum 8

1/2" x 11", A4 51/2" x 81/2", A5 81/2" x 11", A4 B5

Single feed

mode

Duplex mode

Original Weight:

Stack feed

mode

Maximum 34 lb, 128 g/m

Minimum 14 lb, 52 g/m

Single feed

42 lb, 157 g/m

11 lb, 35 g/m

mode

Duplex mode

25 lb, 93 g/m

14 lb, 52 g/m

2 2

Feed-in Unit Capacity: 50 Shee ts (80 g/m2, 20 lb) CFF Original Stack Height:Maximum: 50 mm Original Set: First sheet on top, stack face down

Moving-Original

Scan

Moving-Original

Scan

93 52

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31 July 1995 SPECIFICATIONS

MEMO:

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COPY PROCESSES AROUND THE DRUM 31 July 1995

2. COPY PROCESSES AROUND THE DRUM

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31 July 1995 COPY PROCESSES AROUND THE DRUM

1. DRUM CHARGE In the dark, the charge corona unit gives a uniform positive charge to the selenium drum. The charge remains on the surface of the drum because the photo conductive selenium has electrical resistance in the dark.

2. EXPOSURE An image of the original is reflected to the selenium 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. DRUM POTENTIAL SENSOR The drum potential sensor detects the electric lines of force from the electric potential on the drum to compensate image processing elements.

5. DEVELOPMENT Negatively charged toner is attracted to the positively charged areas of the drum, thus developing the latent image. (The negative triboelectric charge is caused by friction between the carrier and toner particles.)

6. PRE-TRANSFER The pre-transfer corona (PTC) applies a negative dc charge and an ac charge to the drum. The dc charge increases the negative potential of the toner to improve toner transfer to paper. The ac charge decreases positive charge on the drum and makes paper separation easier. The pre-transfer lamp (PTL) also makes paper separation easier by illuminating the drum and decreasing the positive charge on the drum.

7. 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 positive charge is applied to the back side of the copy paper, providing an electrical force which causes the copy paper to be attracted to the drum’s surface. At the same time, the toner particles are pulled to the copy paper from the drum’s surface.

8. PAPER SEPARATION A strong ac corona discharge is applied to the back side of the copy paper, reducing the positive 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 which has low stiffness.

9. CLEANING The cleaning brush first removes remaining toner on the drum surface. Then, the cleaning blade which is angled against drum rotation (counter blade system) removes the rest of the toner. The flick roller mechanically removes the toner on the cleaning brush.

10. QUENCHING

Light from the quenching lamp electrically neutralizes the drum surface.

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18192021222324

MECHANICAL COMPONENT LAYOUT 31 July 1995

3. MECHANICAL COMPONENT LAYOUT

3.1 COPIER

302928 31

121314151617

3 4

5 6

7 8 9

A171V500.wmf

1. First Mirror

2. Second Mirror

3. Third Mirror

4. Inverter Guide Plates

5. Hot Roller

6. Pressure Roller

7. Duplex Tray

8. First Tray

9. Second Tray

10. Pick-up Roller

11. Separation Roller

12. Paper Feed Roller

13. Vertical Transport Unit-Right

14. Third Tray

15. Horizontal Transport Unit

16. Pick-off Pawls 17 Transfer and Separation Corona Unit

18. Vertical Transport Unit-Left

19. Registration Rollers

20. Pre-transfer Corona Unit

21. By-pass Feed Table (Europe version only)

22. Toner Hopper

23. Development Unit

24. Drum Thermistor and Drum Potential Sensor

25. Erase Lamp

26. Fifth Mirror

27. Fourth Mirror

28. Sixth Mirror

29. Charge Corona Unit

30. Quenching Lamp

31. Cleaning Unit

32. Transport Unit

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31 July 1995 MECHANICAL COMPONENT LAYOUT

3.2 ARDF

12 34 5 6 7

1. Original Tray Extension

2. Upper Exit Rollers

10. 1st Pick-up Rollers

11. 2nd Pick-up Rollers

12131415161718

A171V509.img

3. Upper Inverter Gate

4. Lower Inverter Rollers

5. Upper Inverter Rollers

6. Switch Back Gate

7. Switch Back Tray

8. Upper Relay Roller

9. Friction Tab

12. Separation Rollers

13. Lower Relay Roller

14. Pressure Rollers

15. Transport Belt

16. Lower Inverter Gate

17. Lower Exit Rollers

18. CFF Guide

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ELECTRICAL COMPONENT DESCRIPTIONS 31 July 1995

4. ELECTRICAL COMPONENT DESCRIPTIONS

Refer to the electrical compon en t layo ut on the reverse side of the Point to Point (Water proof paper) index numbers.

4.1 COPIER

Name Function Index. No.

Motors

1st Tray Drive Drives the bottom plate in the 1st tray. 64 2nd Tray Drive Drives the bottom plate in the 2nd tray. 65 3rd Tray Drive Drives the bottom plate in the 3rd tray. 71 Charge Wire Cleaner Drives the charge corona wire cleaner. 79 Development Drives the development unit. 50 End Fence Drive Drives the duplex end fence. 128 Fusing Cooling Fan Cools fins of the de-curling roller. 57 Fusing Exhaust Fan Removes the heat in the de-curling unit. 63 Jogger Fence Drive Drives the duplex jogger fences. 129 LCT Drive Drives the bottom plate in the LCT. 150 Lens Horizontal Drive Shifts the lens horizontal position. 55 Lens Vertical Drive Shifts the lens vertical position. 58 Main Drives the main unit components. 77 Mirror Unit Drive Positions the mirror unit. 84 Optics Cooling 1 Removes the heat from the optics unit. 82 Optics Cooling 2 Removes the heat from the optics unit. 81 Scanner Drive Drive the 1st and 2nd scanners. 56 T & S Wire Cleaner Drives the transfer and separation wire cleaner. 75 Toner Supply Rotates the toner supply roller. 78 Vacuum Fan Removes the heat and dust in the machine. 53

Clutches

LCT Drive Transmits the main copier drive to the LCT feed

section.

Left Vertical Transport Unit Drive

Paper Feed - 1st Tray Drives the paper feed roller of the 1st tray. 67 Paper Feed - 2nd Tray Drives the paper feed roller of the 2nd tray. 66 Paper Feed - 3rd Tray Drives the paper feed roller of the 3rd tray. 76 Paper Feed - Duplex Drives the paper feed roller of the duplex unit. 130 Paper Feed - LCT Drives the paper feed roller of the LCT. 138 Right Vertical Transport

Unit Drive Registration Drives the registration roller. 72 Paper Feed - By-pass Drives the paper feed roller of the by-pass feed table. 51

PCBs

DC Drive Drives dc components. 115 DC Motor Drive Drives the dc motors. 125

Transmits the main copier drive to the left vertical transport unit and the 3rd trays.

Transmits the main copier drive to the right vertical transport unit and the 1st and 2nd trays.

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31 July 1995 ELECTRICAL COMPONENT DESCRIPTIONS

Name Function Index. No.

Drum Current Detection Measures the corona current. 106 Main Controls overall machine operation. 121 Motor Control Controls the dc motors. 124 Operation Unit Controls the monitor display. 127 PTL Controls the pre-transfer lamp operation. 120 Quenching Lamp Controls the quenching lamp operation. 119 Interface Interface between the main PCB and other PCBs. 114 Vacuum Motor Controls the vacuum fan motor operation. 108

Power Packs

Charge Provides power for the charge corona wire. 103 Development Bias Provides power for the development bias. 104 PTC Provides power for the pre-transfer corona wire. 107 Separation Provides power for the separation corona wire. 105 Transfer Provides power for the transfer corona wire. 126 Power Supply Unit Provides dc power to dc components. 118

Relays

Anticondensation Heater Provides power to the anticondensation heater. 112 Drum Heater 1 Provides power to the drum heater. 113 Drum Heater 2 Provides power to the drum heater. 110 Fusing SSR Provides power to the fusing lamp. 111 Relay Unit Provides ac power to ac components. 117

Sensor

Auto Response Turns on the display from the screen saver condition. 93 By-pass Table Detects when the by-pass table is opened and

indicates the display on CRT screen. Drum Potential Detects the drum surface voltage. 100 Duplex Entrance Detects misfeeds. 137 End Fence Home

Position Exit Detects misfeeds. 10 Fusing Unit Detects misfeeds. 9 Image Density Measures the density of the image on the drum. 87 Jogger Home Position Detects when the duplex side plate is at the home

Lens Horizontal Encoder Detects the lens horizontal drive motor operation. 5 Lens Horizontal Home

Position Lens Vertical Encoder Detects the lens vertical drive motor operation. 7 Lens Vertical Home

Position Lower Limit - 1st Tray Turns off the 1st tray motor when the tray reaches the

Lower Limit - 2nd Tray Turns off the 2nd tray motor when the tray reaches

Detects when the duplex end fence is at the home

position

position.

Detects when the lens is at the horizontal home

position.

Detects when the lens is at the vertical home position.

down position.

the down position.

136

131

48A

48B

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ELECTRICAL COMPONENT DESCRIPTIONS 31 July 1995

Name Function Index. No.

Lower Limit - 3rd Tray Turns off the 3rd tray motor when the tray reaches

the down position. Lower Limit - LCT Turns off the LCT motor when the tray reaches the

down position. Mirror Unit Encoder Detects the mirror drive motor operation. 37 Mirror Unit Home

Position Paper End - 1st Tray Detects the presence of paper in the 1st tray. 49A Paper End - 2nd Tray Detects the presence of paper in the 2nd tray. 49B Paper End - 3rd Tray Detects the presence of paper in the 3rd tray. 49C Paper End - By-pass

Table Paper End - Duplex Detects the presence of paper in the duplex tray. 132 Paper End - LCT Detects the presence of paper in the LCT. 141 Paper Feed - 1st Tray Turn off the 1st tray paper feed clutch. 15 Paper Feed - 2nd Tray Turn off the 2nd tray paper feed clutch. 14 Paper Feed - 3rd Tray Turns off the 3rd tray paper feed clutch. 20 Paper Feed - Duplex Turns off the duplex paper feed clutch. 133 Paper Feed - LCT Turn off the LCT paper feed clutch. 153 Paper Feed - By-pass Turn off the by-pass paper feed clutch. 36 Paper Size 1 - 1st Tray Determines what paper size is in the 1st tray. 42A Paper Size 1 - 2nd Tray Determines what paper size is in the 2nd tray. 42B Paper Size 1 - By-pass

Feed Paper Size 1 - LCT Determines what paper size is in the LCT. 142 Paper Size 2 - 1st Tray Determines what paper size is in the 1st tray. 41A Paper Size 2 - 2nd Tray Determines what paper size is in the 2nd tray. 41B Paper Size 2 - By-pass

Feed Paper Size 2 - LCT Determines what paper size is in the LCT. 143 Paper Size 3 - 1st Tray Determines what paper size is in the 1st tray. 40A Paper Size 3 - 2nd Tray Determines what paper size is in the 2nd tray. 40B Paper Size 3 - By-pass

Feed Paper Size 3 - LCT Determines what paper size is in the LCT. 144 Paper Size 4 - 1st Tray Determines what paper size is in the 1st tray. 39A Paper Size 4 - 2nd Tray Determines what paper size is in the 2nd tray. 39B Paper Size 4 - By-pass

Feed Paper Size 5 - 1st Tray Determines what paper size is in the 1st tray. 46A Paper Size 5 - 2nd Tray Determines what paper size is in the 2nd tray. 46B Paper Size 6 - 1st Tray Determines what paper size is in the 1st tray. 45A Paper Size 6 - 2nd Tray Determines what paper size is in the 2nd tray. 45B Paper Size 7 - 1st Tray Determines what paper size is in the 1st tray. 44A Paper Size 7 - 2nd Tray Determines what paper size is in the 2nd tray. 44B Paper Size 8 - 1st Tray Determines what paper size is in the 1st tray. 43A Paper Size 8 - 2nd Tray Determines what paper size is in the 2nd tray. 43B

Detects when the mirror unit is at the home position.

Detects the presence of paper in the by-pass table.

Determines what paper size is in the by-pass feed

tray. (European version only)

Determines what paper size is in the by-pass feed

tray. (European version only)

Determines what paper size is in the by-pass feed

tray. (European version only)

Determines what paper size is in the by-pass feed

tray. (European version only)

48C

146

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31 July 1995 ELECTRICAL COMPONENT DESCRIPTIONS

Name Function Index. No.

Paper Volume - 1st Tray Detects the amount of paper in the 1st tray. 38A Paper Volume - 2nd Tray Detects the amount of paper in the 2nd tray. 38B Paper Volume - 3rd Tray Detects the amount of paper in the 3rd tray. 38C Paper Volume - LCT Detects the amount of paper in the LCT. 148 Registration Sensor Detects the lead edge of paper to determine the stop

timing of a feed clutch and detects misfeeds. Return Home Position Detects when the 1st scanner is at the return position. 31 Scanner Home Position Detects when the 1st scanner is at the home position. 8 Sheet Through Home

Position Toner Cartridge Detects when a toner cartridge is in the machine. 2 Toner Coil Overload Detects the toner collection coil drive gear operation. 1 Toner Near End Detects toner near end condition. 35 Transport Detects misfeeds. 18 LCT Paper Position Detects the top sheet position in the LCT tray. 140 Upper Limit - 1st Tray Sends signal to stop lifting up the 1st tray bottom

Upper Limit - 2nd Tray Sends signal to stop lifting up the 2nd tray bottom

Upper Limit - 3rd Tray Sends signal to stop lifting up the 3rd tray bottom

Upper Limit - LCT Sends signal to stop lifting up the LCT bottom plate. 151 Duplex Exit Jam detector. 16

Detects when the 1st scanner is at the 1 sheet

through home position. (European version only)

plate.

Solenoids

Cleaning Brings the cleaning blade into contact with the drum. 54 Inverter Gate Drives the inverter gate up and down. 62 Junction Gate Drives the junction gate up and down. 61 LCT Lock Locks the LCT. 139 Pick-up - 1st Tray Lifts the pick-up roller of the 1st tray. 69 Pick-up - 2nd Tray Lifts the pick-up roller of the 2nd tray. 70 Pick-up - 3rd Tray Lifts the pick-up roller of the 3rd tray. 73 Pick-up - LCT Lifts the pick-up roller of the LCT. 149 Pick-up - By-pass Lifts the pick-up roller of the by-pass feed table. 83 Pinch Roller Brings the return pinch rollers into contact with a

paper. Duplex Pressure Plate Brings the pressure plate on papers in the duplex unit. 134 Positioning Lowers the positioning roller in the duplex unit. 135 Original Scale Moves the original scale to the sheet through position

(European version only). By-pass Gate Moves the by-pass gate to the down position. 80

Switches

1st Tray Down Lowers the 1st tray bottom plate. 47A 2nd Tray Down Lowers the 2nd tray bottom plate. 47B 3rd Tray Down Lowers the 3rd tray bottom plate. 47C LCT Down Lowers the LCT bottom plate. 147

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ELECTRICAL COMPONENT DESCRIPTIONS 31 July 1995

Name Function Index. No.

Anticondensation Turns on the tray heaters. 23 Error Reset Resets error condition. 11 LCT Cover Turns off components when the LCT top cover is

open. Left Door 1 Turns off the main motor when the left door is open. 25 Left Door 2 Turns off dc 24 volts lines when the left door is open. 24 Main Supplies power to the copier. 26 Right Door 1 Turns off dc 24 volts lines when the right door is open. 21 Right Door 2 Turns off the main motor when the right door is open. 17

Heaters

1st Tray Removes humidity from the paper in the 1st tray. 91 2nd Tray Removes humidity from the paper in the 2nd tray. 92 3rd Tray Removes humidity from the paper in the 3rd tray. 94 Anticondensation Prevents moisture from forming on the lens and

mirrors. Drum Warms the drum when it gets too cool. 95 Exposure Lamp Warms the exposure lamp when it gets too cool. 86 LCT Removes humidity from the paper in the LCT. 145

152

101

Lamps

Exposure Exposes the original with high intensity light. 85 Fusing Provides heat to the hot roller and keeps the roller at

the operating temperature. Pre-Transfer Removes excessive positive charge from the drum

surface to the transfer and separation process. Quenching Electrically neutralizes the drum surface prior to

charging. Eraser Discharges the drum outside the image area.

Provides lead/trail edge erase.

Thermistors

Drum Monitors the drum temperature. 99 Fusing Monitors the hot roller temperature. 88

Other Components

Total Counter Keeps a count of the number of copies made. 116 FL Stabilizer Stabilizes power to the exposure lamp. 109 Thermofuse Provides back-up overheat protection in the fusing

unit. Anticondensation

Thermoswitch

Turns off the anticondensation and drum heaters.

102

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31 July 1995 ELECTRICAL COMPONENT DESCRIPTIONS

4.2 ARDF

Symbol Name Function Index. No.

Motors

M1 M2 Belt Drives the transport belt. 16

M3 Inverter Drives the inverter rollers and the exit rollers. 17 M4 Job Separation Drives the job separator. 5

Circuit Boards

PCB1 DF Main Controls overall ARDF functions. 3 PCB2

Solenoids

SOL1

SOL2 Inverter Gate Opens the inverter gate. 23 SOL3

SOL4

Feed-in Drives the pick-up rollers, separation rollers

and relay rollers.

Indicator Indicates the Insert Original indicator and the

Auto Feed indicator.

Switch Back Switches the switch back gate position to

directs the original to the switch back tray or onto the exposure glass.

Moving Original Scan Gate

Sheet-through Guide

Opens the moving original scan gate (European version only).

Moves the sheet-through guide to the sheet through position (European version only).

Sensors

S1 Entrance Cover Detects if the entrance cover is open. 4 S2 Lift Detects if the transport unit is open. 14 S3 Inverter Cover Detects if the inverter cover is open. 22

S8 S9 Inverter Jam Detects paper jams in switch back operation. 18

S10

S11

S12 Exit Detects paper jams. 21

S13

Pick-up Roller H.P.

Job Separation H.P.

Job Completion Detects that last original of the first job is fed

Original Detects if the original is set on the original

Registration Sets the feed-in motor, belt motor and inverter

Inverter Registration

Inverter Entrance Sets the inverter motor and the belt motor off,

CFF Detects if the computer form is set in the CFF

Detects if the pick-up roller is in the home position.

Detects if the job separator is in the home position.

from the original table.

table.

motor off timing. Detects original misfeed.

Sets the inverter motor and the belt motor off, reversing timing. Detects original jams.

reversing timing, inverter solenoid and switch back solenoid off timing.

guide. Counts the holes lined up on the computer form.

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ELECTRICAL COMPONENT DESCRIPTIONS 31 July 1995

S14 Original Width Detects the original width. 13 S15 Timing Supplies timing pulses to the DF main board. 10

S16

Others

Oth1

Oth2

Moving Original Scan Entrance

CFF Guide Switch Detects whether the CFF guide is in the rear

Sheet Feed Clutch

Detects when the original is set on the moving original scan entrance (European version only).

end position or not (European version only). Drives the sheet feed rollers (European

version only).

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31 July 1995 DRIVE LAYOUT

5. DRIVE LAYOUT

A171V510.img

A171V511.img

A171V508.img

A171V506.img

A171V507.img

1. Main Motor

2. Development Drive Motor

A171V512.img

A : Development Unit B : Cleaning Unit C : Relay Transport Unit (to LCT & By-pass Table) D : Fusing Unit E : Vertical Transport Unit-Right F : Duplex Unit G: Vertical Transport Unit-Lef t

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PAPER PATH 31 July 1995

6. PAPER PATH

6.1 SINGLE SIDED COPY – COPY FACE DOWN

6.2 DUPLEX MODE (1ST SIDE)

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A171V502.wmf

31 July 1995 PAPER PATH

6.3 DUPLEX MODE (2ND SIDE)

6.4 IMAGE OVERLAY MODE (1 ST SIDE)

A171V503.wmf

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A171V504.wmf

PAPER PATH 31 July 1995

6.5 IMAGE OVERLAY MODE (2ND SIDE )

A171V505.wmf

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SECTION 2

DETAILED SECTION

DESCRIPTIONS

Drum Current Detection PCB

31 July 1995 PROCESS CONTROL

1. PROCESS CONTROL

1.1 OVERVIEW

The characteristics of each unit which is relat ed to the cop y ima ge reproduction are changed by various factors. To get stable images over long periods and in continuous copy run s, th ese chara cteristic changes have to be compensated. The following figure and table show how these facto rs are compensated on this copier.

Potential Sensor

Toner Supply

Development Bias

Exposure Lamp

PTC

Main PCB

Transfer Corona

Charge Corona

ID Sensor

Separation Corona

: Sensing Item : Controlled Item

A171D522.wmf

2-1

PROCESS CONTROL 31 July 1995

Section Characteristics Causes of Change Compensation Method

Drum Charge Potential Repeat Stress

Temperature Humidity

Sensitivity Repeat Stress

Temperature Humidity

Residual Voltage

Charge Corona

Exposure Lamp Intensity Repeat Stress Measure the drum potential of a part

Development Amount of

Charge Potential Dirtiness

Mirror Reflectivity Lens Clearness

Toner Charge

Repeat Stress Temperature Humidity

Temperature Humidity

Dirtiness

Repeat Stress Temperature Humidity

Measure the drum potential of a part that was not exposed (Dark Potential) with the potential sensor and adjust the charge corona output.

Measure the drum potential of a part that was exposed (Light Potential) and adjust the exposure lamp voltage.

Measure the drum potential of a part that was erased by the erase lamp (residual voltage) and adjust the development bias, light potential, and dark potential

Measure the drum potential of a part that was not exposed (dark potential) and adjust the charge corona output.

that was exposed (light potential) and adjust the exposure lamp voltage.

Measure the reflected light intensity of the ID sensor pattern and adjust the toner density in the development unit.

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31 July 1995 PROCESS CONTROL

1.2 IMAGE CONTROL

1.2.1 Latent Image Control

Charge

Exposure

Black White

Erase

Potential Sensor

Drum

A171D507.wmf

The figure shows the change s of the drum potential durin g the copy process. V0: The drum potentia l just af te r charging 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 t he expo sure of the

erase lamp.

2-3

PROCESS CONTROL 31 July 1995

Drum Potential

LightOriginal DensityDark

A171D519.wmf

The above figure shows the relatio nsh ip be twe en the drum pote nt ial and th e original density (exposing ligh t intensity). To get constant copy quality, this relationship must be maintained.

Since this relationship tends to change to the one rep resented by the dotted line by various factors, compensations are required as follows:

A decrease in dark voltage (Vd) is compensated for by increasing the charge corona output. A increase in light voltage (VL) is compensated for by increasing the exposu re lamp voltage. Since the resid ual vo lta ge (V r ) increase cannot be compen sat ed for by increasing the lamp voltage , it is compensated by increasing the development bias voltage and changing the Vd and VL standard value.

1.2.2 Image Density Control

To maintain constant copy image density, the ID sensor dete cts the toner amount of the ID sensor pattern. From this, it is understood that drum potential is stabilized with the above compe nsa tions. According to the detection results, the ton er density in the development unit is controlled so that the toner amount on the sensor pattern is constant.

The following sections explain the details of these compensations.

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31 July 1995 PROCESS CONTROL

1.3 PROCESS CONTROL DATA INITIALIZATIO N

The following flow chart shows all t he st eps tha t will be performed whenever the main switch is turned on while the hot roller temperature is below 100°C. This initializes all the process control set tings.

Main SW On (Fusing Temp. < 100°C)

Drum Potential Sensor Calibration (Fusing Temp . = 160°C)

Drum Conditioning Start (Fusing Temp . = 160 ° C)

• Exposure lamp ON

Vsg Adjustment

Lamp Intensity Sensor Calibration

Charge Corona Current Adjustment

Vr Measurement

• Lens position shift

• Exposure lamp OFF

• Scanner moves to return position (Vd Pattern)

• Exposure lamp ON

Vd Correction

• Exposure lamp OFF

• Scanner returns to home position (VL Pattern)

• Exposure lamp ON

VL1 Correction

• Exposure lamp OFF

V01 Detection

• Scanner moves to re tu rn po sitio n (ADS Pat te rn)

• Exposure lamp ON

ADS Adjustment

2-5

TRIG 1 (800V)

TRIG 2 (100V)

PWM

Sensor

PROCESS CONTROL 31 July 1995

1.3.1 Drum Potential Sensor Calibration

[A]

A171D585.img

Potential Sensor

Bias P.P.

Case

Sensor

Output

Amp.

Drum

A171D512.wmf

RA2

RA1

Drum Current Detection PCB

Relay

Main PCB

A171D511.wmf

The drum potential sensor [A] is locat ed just ab ove the deve lop men t un it. The sensor has a detector which detect s the elect ric lin es of force from the electric potential on the drum. The output of th e sensor de pe nds of th e number of electric lines of force.

Since the output of the sensor is affected by enviro nme nt al conditions, such as temperature and humidity, the sensor output is calibrated du ring proce ss control data initialization.

The drum current detection board ha s two rela y contacts. Usually RA2 grounds the drum. However, during the initialization, the main PCB turns RA1 on and RA2 off and applies the deve lopment bias to the drum shaft.

By measuring the outputs of the drum potentia l sensor when +100 V and +800V are applied to the drum, the sensor output is calibra ted auto mat ically.

2-6

31 July 1995 PROCESS CONTROL

1.3.2 Drum Conditioning

When the fusing temp erature reaches 160°C, th e mach ine starts the drum conditioning proce ss. In this mode, all the coronas and lamps around the drum are activated and drum sensitivit y is sta bilize d, as in cont inu ou s copy runs.

1.3.3 Vsg Adjustment

During drum conditioning, the ID sensor checks th e bare dru m’s reflectivity and calibrates the ou tp ut of the ID sensor to +4 V.

1.3.4 Lamp Intensity Sensor Calibration

Main PCB

PWM

FL Stabilizer

A171D569.img

The exposure lamp intensity is monit ored by the main PCB through the fibe r optics cable. A photodiode on the main PCB con vert s the light inte nsity to a dc voltage. The main PCB sen ds a PWM sign al with a 100% duty cycle to the FL stabilizer and checks the monitored voltage, adjusting it to +3 V. This +3 V is used as the light intensity standard.

2-7

MainPCB

Potential S.

PROCESS CONTROL 31 July 1995

1.3.5 Charge Corona Current Adjustment

Id Set

Drum Current Detect PCB

A11D502.wmf

The charge corona current is measu red and adju ste d au to mat ically by the drum current detect PCB.

The charge corona current flows to the drum current dete ct PCB through the drum and the drum shaft. The drum sha ft is gro unde d by the dru m current detect PCB usually. However, during the process control data initialization, the main PCB activates the corona current circuit in the drum current detection PCB which converts the drum curre nt to a voltag e and sep ara te s it into ac and dc component outputs. Then, the main PCB read s the m t hro ug h A/D converters as digital da ta. The main PCB adjusts the coro na current by controlling the PWM signal to the charge corona power pack.

When the auto drum current adjustment mode is selected by th e SP mode, the drum current dete ct PCB is used to measure and adjust oth er corona outputs in the same way.

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31 July 1995 PROCESS CONTROL

1.3.6 Vr Measurement

Drum Potential

Dark

Original Density

Light

A171D510.wmf

The drum residual voltage (Vr) tends to in crea se du ring the drums life due to electrical fatigue. The resid ual vo lta ge cannot be red uce d eve n if the exposure lamp voltage is increase d. Therefore, the Vr chan ge has to be compensated by other means.

The main PCB checks the drum pot en tial just after the erase lamp exposure, by the drum potential se nso r d urin g drum conditioning. The dru m pot en tia l is in fact Vr. This measured Vr is used as the sta ndard for the following other compensations.

1. Vd Correction

2. VL1 Correction

2-9

Original Density

PROCESS CONTROL 31 July 1995

1.3.7 Vd Corr ection

Drum Potential

Exposure Glass

Vd Pattern

Dark

Light

A171D508.wmf

A171D520.wmf

The drum potential just after the bla ck pat te rn (Vd Pat te rn) is expo sed (Vd: Dark Potential) tends to lowe r d urin g 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 return posit ion and the Vd pattern (Black) stuck on the bottom side of the exposure glass bracket is exposed on the drum.

The main PCB measures Vd thro ug h the drum potential senso r and adju st it to a target value by adjusting the charge power pack output.

On the other hand, there is a change of the drum resid ua l voltage (Vr), so that the target Vd voltage is compensated as follows:

Target Vd Value: Vd = Vr + 770 V - 20 M NOTE: M is the sett ing for the Latent Image Adj. in the SP mode.

The adjusted charge powe r pack ou tput control value (PWM value) is kept in memory until the next initialization.

If the target value cann ot be ach ieve d within the charge power pack ou tp ut control range, the copie r indica tes the system error on the CRT screen. The copier tries the Vd check again af ter the error reset. Even if the secon d Vd adjustment fails, no SC condition is displayed. The previous power pack output control data will be used in this case.

2-10

Original Density

31 July 1995 PROCESS CONTROL

1.3.8 VL Corr ection

VL Pattern

Drum

Light

A171D521.wmf

A171D508.wmf

Potential

Dark

Dirty optics and/or exposure lamp det erio ration decreases the intensit y of th e light that reaches the drum. In additio n to this, the drum sen sitivit y also changes during the drum’s life. These fa ctors change the drum potential just after white pattern exposure (VL: Light Potential).

To check the actual VL, the first scanner moves to the home position and the VL pattern (White) stuck on the bottom side of the exposure glass bracket is exposed on the drum.

The main PCB measures the VL through the drum potential sen sor an d adjusts it to a target value by ad justing the exposure lamp output.

The residual voltage cha ng e also aff ects VL, so that V L ’s target voltage is compensated as follows:

Target Value of VL: VL1 = Vr + 50 – 10 N -15 M (volt) NOTE: N is the setting fo r th e exposure lamp adjustment in the SP mod e.

M is the setting for th e Latent Image Ad j. in th e SP mode.

The adjusted exposure lamp out pu t con tro l value (PWM value) is kept in memory until the next initialization.

If the target value cann ot be ach ieve d within the exposure lamp out pu t control range, the copie r indica tes the system error on the CRT screen. The copier tries the VL check again after the SC reset. Even if the secon d VL adjustment fails, no SC condition is displa yed. The previous exposure lamp output control data will be used in this case.

2-11

Light

PROCESS CONTROL 31 July 1995

1.3.9 V01 Measuring

Drum Potential

Dark

Original Density

A171D513.wmf

Since the ID sensor pattern on the drum is made by the erase lamp and charge corona (except for B4 /81/2" x 14" copy mode due to the len s horizo ntal movement. See toner density detection and supply section for details), the sensor pattern density varies with drum potential just after the charg e coro na (V0) is applied.

To measure the toner density prop erly, the deve lop men t bias for the ID sensor pattern is corrected by mea surin g th e actua l drum po te nt ial afte r t he charge corona.

During the process control data initializatio n, the drum pote ntial af te r the charge corona is applied when the drum sensitivit y is stabilize d (V 01) will be measured and used to det ermine the bias voltage for th e ID sensor pattern development in continu ou s copy run . The details will be explained in the toner density detectio n sect ion.

2-12

Exposure Glass

31 July 1995 PROCESS CONTROL

1.3.10 ADS Adjustment

ADS Pattern

A171D508.wmf

A171D570.img

The ADS pattern is locate d un derneath the exposure gla ss bracke t. During the process control data initializa tion, the ADS reference voltage is adjust ed .

When the first scanner is moved to the return posit ion for the Vd adjustment, the main PCB checks the ADS voltage throu gh the ADS fib er op tics cab le. The measured voltage is calibrat ed to th e sta nd ard voltage (3 V) as the reference for the auto image density control.

2-13

Original Density

PROCESS CONTROL 31 July 1995

1.4 COMPENSATIONS DURING COPY CYCLE

During continuous copying , th e drum sensitivity changes due to the elect rical fatigue. The drum sensitivity also changes during rest time.

The following compensations are used for the drum sensitivity cha nges in th e copy cycle:

VL Pattern

VBB

Drum Potential

A171D508.wmf

Dark

Light

A171D510.wmf

1.4.1 VL Compe nsa tion

The drum light potential (VL) is changed du ring the copy cycle. To get constant image qua lity in con tinuous copy runs, the develop ment base bias is compensated during the copy cycle.

At the beginning of each original scanning, the VL sensor pattern is developed on the drum. The main PCB mon ito rs t he drum potential (VL2) of the latent image of the VL sensor pattern throu gh the drum pote nt ial sen sor, and adjusts the develop men t ba se bias. See development bias section for de ta ils.

Development Base Bia s:

VBB = VL2 + 280 – ∆ V + 10 N – 15 M

∆ V = VL2 – Vr (Maximum ∆ V = 210, Minimum ∆ V = 110)

NOTE: N is the setting fo r th e exposure lamp adjustment in the SP mod e.

M is the setting for th e Latent Image Ad j. in SP mo de .

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31 July 1995 PROCESS CONTROL

1.4.2 V02 Measuring

Start key

Charge Corona

Exposure Lamp

Scanner

Drum Potential Sensor

F R

V02 VL2 VL2 VL2 VL2 VL2 VL2 VL2 VL2

A171D523.wmf

During the process control data initializatio n, V 01 is measured to determine the development bias for t he ID sensor pattern in continuous cop y runs. This bias cannot be used for the initial part of the copy run (less than 10 copies) due to the different drum potential after the charg e coro na is applied.

Whenever the Start ke y is pressed, the drum potential a ft er the charge corona is measured at the beg inn ing of the copy run (V 02).

V02 is used to determine the developmen t bia s vo lta ge for the ID sen sor pattern which is made at the first copy.

The details will be explained in the Image Density Control section.

2-15

DRUM 31 July 1995

2. DRUM

2.1 OVERVIEW

[E]

[A]

[C]

[B]

A171D514.wmf

[F]

A171D579.img

This model uses an FO-type drum made by applyin g an uret ha ne re sin coating [A] on an F-type dru m [B]. This coating provides a long life an d minimize the white line problems on the half-tone areas.

[D]

For the F-type drum, the charge carrying layer [C] is made by the dru m conditioning. Since th e FO-t ype drums are coated after the charge carrying layer has been made, it is not nece ssary to perform the drum conditio nin g at the new drum installation.

When drum temperature drops below th e permissible level, extre me sensitivity changes occur. Additio nally, th e te mpe rat ure changes can cause condensation. To maintain a constant drum temperature, a drum heater [D] (100 V 140 W) which is controlled by a thermistor [E] and two thermoswitches [F] is used.

2-16

Drum Thermistor

31 July 1995 DRUM

2.2 DRUM HEATER CONTROL

160°C

Drum Heater

65°C

Drum Thermistor

A/D Converter

Drum Heater 1

Drum Heater 2

Relay PCB

Drum Heater 1

Drum Heater 2

Main PCB

A171D509.wmf

The drum thermistor monitors the drum surface temp era tu re. When the measured temperat ure reaches 41°C, the main PCB determines that the copier is ready to make copies.

When the main switch is off, the drum heater relays (RA353 and RA354) are off, so that the drum heater is controlled by the 65°C thermoswitch. The thermoswitch is on at 50°C and off at 65°C.

When the main switch is on, RA35 4 is o n and bypasses the 65°C thermoswitch from the drum heater control circuit . RA3 53 turn s on or off according to the temp era ture detected by the drum t he rmisto r.

The drum surface temperature is controlle d betwe en 41°C and 50°C. To minimize the power consumpt ion , RA353 is turned on to bypass the dru m

heater during the copy cycle.

2-17

DRUM CHARGE 31 July 1995

3. DRUM CHARGE

3.1 CHARGE CORONA UNIT

A171D505.wmf

[A]

A171D580.img

This copier uses a dual carbon coa te d tungsten wire corotron for t he drum charge. The corona wire ge nerates a corona of positive ions when the charge power pack [A] applies a high voltage.

The output of the charge power pack is determined by the CPU based on the process control data.

The charge power pack has a leakage sensor. If a leak (short circuit) is sensed, the outp ut is interrupted.

2-18

31 July 1995 DRUM CHARGE

3.2 CORONA UNIT VENTILATION

A171D578.img

If ozone produced by the corona charge stays in the charge corona area, it may cause uneven corona charg ing to the drum. To prevent th is, ozone is vacuumed out by the vacuum fan through the duct and tone r filt er in the transport unit, th en chan ge d to oxyge n by the ozone filter before blown out of the copier.

2-19

DRUM CHARGE 31 July 1995

3.3 CORONA WIRE CLEANER

A171D577.img

Paper dust, or toner particles on the charge corona wires may interfere with charging and cause an uneven charge on the drum. The wire cleane r prevents this problem by auto matically wiping the charge corona wires clea n. Once every 5000 copies, the wire clean er is activa te d whe n the main swit ch is turned on. The hot roller temperature must be less than 100°C for th e wire cleaner to be activated.

When the dc motor in the fro nt end block tu rns on , it drive s t he clean er bracket from the home positio n to the re ar end of the corona unit and then back again.

2-20

Charge Corona P.P.

31 July 1995 DRUM CHARGE

3.4 CHARGE CORONA POWER PACK

24 V

Door SW

DC Power Supply

Main PCB

DC Drive PCB

Drum Current Detect PCB

GND

PWM TRIG

A171D506.wmf

The main PCB sends a PWM (Pulse Width Modulation) signal to the charge corona power pack. According to the PWM ratio, the dc power p ack outputs a high dc voltage to the charg e corona wires. The main PCB determin es the PWM ratio based on the process contro l dat a.

There is a safety relay (RA303) on the dc drive board which is activated by a signal from the main PCB. In case of the SC conditions rela te d to the high voltage devices and the abnormal exposure lamp on, the main PCB turns the RA303 to cut the power of dc 24 V to the power pack thro ugh its con ta ct.

2-21

ERASE 31 July 1995

4. ERASE

4.1 OVERVIEW

[A]

A171D573.img

The electrical charge of the area that does not require any image will be removed by the erase lamp unit [A].

This reduces toner consump tio n, and the load of the cleaning un it. The erase lamp unit consists of 90 yellow-gre en LEDs. This redu ces dru m

light fatigue and allows precise control of the light width. The erase lamp unit is controlle d by th e main PCB based on factors such as

the reproduction ratio , pape r size, SP mode sett ings, and the image editing settings.

The maximum erase margin error in the image editing mode is 6 mm.

2-22

VL Pattern

31 July 1995 ERASE

4.2 ERASE LAMP CIRCUIT

Main PCB

Erase Lamp Unit

DC Power Supply

A171D504.wmf

The main PCB sends the serial bit data to the erase lamp un it with the clock signal. The latch signal ho lds th e ON/OFF condition of the LEDs.

The following charts show the era se lamp cont rol timin g.

1. When the ID sensor patt ern is not made. (A4/LT, Full Size, and 3rd Feed Mo de)

Start Main Motor ON Regist Trail Edge Main Motor OFF

All ON

VL Pattern

All ON

2. When the ID sensor patt ern is made. (A4/LT, Full Size, and 3rd Feed Mo de)

Start Main Motor ON Regist Trail Edge Main Motor OFF

All ON

ID PatternV02

NOTE: 1. Depen ds on the paper feed stat ion.

2. Depends on the paper size.

3. Will be changed in Margin Adjustme nt and Imag e Ed itin g Mod e.

2-23

All ON

A171D517.wmf

OPTICS 31 July 1995

5. OPTICS

5.1 OVERVIEW

[A]

[C]

[B]

A171D587.img

The optics unit reflects an ima ge of th e orig inal on the exposure glass ont o the selenium drum. This forms a lat ent electrical image of the original.

On this model, to minimize power consu mpt ion, a fluorescent lamp is used for the exposure lamp [A].

Six high reflection mirrors are used to make the optics unit smaller and obtain a the wide reproductio n rat io range (50 – 200%).

The lens [B] is driven by two stepper mot ors fo r (1) ve rtica l direction (parallel to the paper feed direction) and (2) horizontal direction movements.

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

The exposure glass has a special coat ing on one side to minimize the static electricity which may be produce d by th e original using the document feeder. The coated side is marked and shou ld fa ce up .

2-24

31 July 1995 OPTICS

5.2 SCANNER DRIVE

[C]

[D]

[A]

[B]

A171D576.img

A dc servo motor is used as the scanne r d rive mot or [A]. The scanner drive motor drives first [B] and second scanner [C] using four

scanner drive wires. The second scanner spe ed is half of the first scanner speed.

The first and second scanners are supported by the front and rear guide rails [D]. To minimize the friction between the scanners and guide ra ils, the pla y of the scanner movement is minimized by high wire tension.

2-25

OPTICS 31 July 1995

5.3 SCANNER POSITION SE NSO RS

[A]

[B]

A171D586.img

There are two scanner posit ion sensors located at the front side of the opt ics unit.

The scanner home position sensor [A ] is used to dete ct th e home po sitio n at the machine initializat ion and during the scan cycle.

The scanner return position senso r [ B] is used to det ect the scanner po sitio n for the process control data in itia lizat ion (Vd and ADS data). The return position sensor is not used during no rmal cop ying .

2-26

31 July 1995 OPTICS

5.4 VERTICAL LENS DRIVE

[B]

[C]

[A]

A171D581.img

The lens vertical drive motor [A] changes the lens vert ical po sitio n in accordance with the selected reproduction ra tio .

A stepper motor (Approx. 1. 8° (0. 05 mm)/ste p) is u sed to drive the lens through the lens drive belt.

The lens vertical home position sensor [B ] de te cts th e len s vertica l position for full size mode. The motor con trol PCB keeps track of the len s posit ion based on the number of pulses sent to the lens vertical drive motor.

The lens vertical drive encoder [C] installe d on the drive pulley is used to detect if the vertical lens base locks.

2-27

OPTICS 31 July 1995

5.5 HORIZONTAL LENS DRIVE

[B]

[A]

A171D582.img

The original horizontal position on the exposure glass varies in modes (such as platen, ADF, and CFF modes) for easy original handling. On the other hand, the cente r is the standard position of th e pa per feed.

Therefore, the len s horizontal position has to be change d according to paper size, reproduction ratio, and the original modes.

A stepper motor (approx. 7. 5° (0. 35 mm)/ste p) is u sed to drive the lens through the lens drive wire.

The lens horizontal home posit ion sensor [A] is used to detect the le ns horizontal position for A4/LT sidewa ys, full size, an d ADF mode.

The other positions are determined by countin g the numbe r of mot or drive pulses.

The lens horizontal drive encoder [B ] installed on the drive pulley is used to detect if the horizonta l le ns ba se locks.

2-28

31 July 1995 OPTICS

5.6 HORIZONTAL LENS POSI TIONING

5.6.1 For Or igi nal Posi tion

Lens Position

Copy Paper

There are three standard origin al po sitio ns fo r t he plat en , ADF, and CFF modes.

ADF mode original position is 5 mm to rea r of th e platen mode original position to maintain the original transp ort path (5 mm from th e front scale).

Horizontal

Original Front Edge

Platen

A171D516.wmf

CFF mode original position is 17.7 mm (5 + 12.7 mm) to rear of the platen mode original position. This is to main tain the traction hole part transport path (12.7 mm) in ADF.

The above figure shows the lens horizo nt al po sitio ns fo r each origin al mode when the identical size paper is used.

5.6.2 For Pa per Size

Copy Paper

Lens Position

A171D503.wmf

Horizontal

Original Front Edge

To keep the high paper fee d pe rfo rmance, the center is assigned as the paper feed standard posit ion. Therefore, the lens horizontal position is changed according to the paper size.

The figure shows the lens horizon tal p osit ion for ea ch pa per size in full size mode.

2-29

Horizontal

Original Front Edge

OPTICS 31 July 1995

5.6.3 For Reproducti on Ratio

Copy Paper

Lens Position

Vertical

A151D515.wmf

When the reproduction ratio is changed, the vertical position of the lens is changed. At the same time , th e to ta l focal length has to be changed to adjust the image focusing. For t his fo cal length change, the horizo ntal position of the lens is also adjusted.

The figure shows the lens horizontal position for 50, 10 0 an d 200%.

2-30

31 July 1995 OPTICS

5.7 MIRROR UNIT DRIVE

[A]

A171D567.img

To compensate the focus change at the reproductio n change, the mirror unit (4th and 5th mirrors) position is changed.

A stepper motor (Approx. 7.5° (0. 1 mm)/step ) is used for the mirror unit drive. A mirror unit home position sensor [A] is used to dete ct the un it position for

full size mode. The motor control PCB keeps track of the unit position based on the number of motor drive pulses.

2-31

Vertical Drive

OPTICS 31 July 1995

5.8 MOTOR DRIVE CIRCUIT

Sensors Encoders

Main PCB

Serial Interface

Motor Control PCB

DC Motor Drive PCB

Scanner Drive

Encoder

A171D518.wmf

Horizontal Drive

Mirror Unit Drive

The motor control PCB communicat es with the main PCB through the serial interface lines. The motor control PCB monitors all the sensor signals and controls the motors through the dc motor drive PCB.

The development mot or an d th e main motor are also be controlled by the dc motor control PCB.

2-32

31 July 1995 OPTICS

5.9 EXPOSURE LAMP UNIT

[C]

A171D568.img

[A]

[B]

A171D584.img

[D]

This copier uses a fluorescent lamp [A ] (100 V 84 W). This has the following advantages:

• Low power consumption

• There is no bright point and it is easy to get even luminescence

• A narrow light wave band allows more accurate focusing for various

kinds of originals

• High-speed scanner operation vibration resistance

• Omni-direction al lumin escence reduces original shadow

Since low fluorescent tu be temperature will result in delayed lighting and intensity variation, a tube-t ype heate r (3 8 V 60 W) [B] is u sed to main ta in the fluorescent tube te mp erature at approximately 4 0°C.

The lamp unit has a thermister [C] to monitor the lamp temp era tu re and a thermofuse [D] (139°C) for saf ety.

2-33

OPTICS 31 July 1995

5.10 EXPOSURE LAMP CONTROL

[C]

PWM

[B]

[A]

A171D572.img

Exposure lamp intensity must be stab ilized durin g the cop y cycle to get a constant latent ima ge on th e dru m. The main PCB [A] monitors and main ta ins the light intensity through a fiber optics cable [B] . Acco rdin g to the measured value, a lamp power signal (PWM signal) is sent to th e flu orescent lamp stabilizer [C].

The PWM signal output is determined base d on the stan da rd valu e (+3 V at PWM 100% duty cycle) which is set at the process control data initialization (see the Process Control Section for details).

2-34

26 mm

31 July 1995 OPTICS

5.11 AUTO IMAGE DENSITY CONTROL

50 mm

A171D571.img

26 mm

50 mm

166 mm

A171D501.wmf

The original background density is read th rou gh a fibe r opt ics cable on the exposure lamp unit. The sample d strip is at the leading edge of the original and the size depends on the scan ne r sp eed (reproduction ratio).

The fiber optics cable cond uct s t he lig ht to a ph ot od iode on the main PCB. The photodiode then convert s the density to the ADS volt ag e. The CPU compares it with the standard ADS value (+3 V), which is set at the process control data initializatio n by che cking density of the white pat te rn unde rne at h the left exposure gla ss holder and adjust the develop men t bias accordingly. Detailed bias control is described in the deve lop ment bias section.

2-35

OPTICS 31 July 1995

5.12 UNEVEN LIGHT INTENSITY CORRECTION

[B]

A171D575.img

[A]

[C]

A171D583.img

The slit plate [A] corrects the uneve n ligh t int en sity at the ends and cent er of the fluorescent lamp [B] and even ly distrib utes light reflected from the orig ina l.

To compensate for reduced light at the lens edges, the shad ing plat e [C] is located in front of th e len s. Additionally, the shading plate compensates the light intensity when the lens horizo nt al position is shifted.

2-36

31 July 1995 OPTICS

5.13 ANTI-CONDENSATION HEATER

[B]

[A]

A171D566.img

To prevent condensatio n in the op tics unit, a 40 W anti-condensation heater [A] is installed at the bo tt om of the lens unit. The anti-condensation heater is controlle d by a thermo switch [B] (On at 17°C, Off at 25°C) under the following cond itio ns:

1. The main switch is off.

2. The main switch is on, fusing lamp of f in sta nd -by mod e.

3. Machine off condition in wee kly timer mode.

The anti-condensation heat er ha s a thermofuse (169°C).

5.14 OPTICS COOLI NG FAN

[B]

The light intensity will be decre ased if the fluorescent lamp temperature becomes too high. The optics coolin g fa n [A] blows in cool air from outside through an air filter [B]. Air f rom th e fan also passes through th e 6t h mirror slit [C] to the drum area. This prevents th e optics area from being contaminated by scattered toner in th e dru m u nit .

[A]

[C]

A171D5747.img

2-37

[D]

[A]

DEVELOPMENT 31 July 1995

6. DEVELOPMENT

6.1 OVERVIEW

[E]

[C]

[F]

[G]

[B]

A171D594.img

This copier uses a double roller (diamet er 20 mm each) develo pment system. This system differs from single roller development system in that (1) it develops the image in a narrow are a an d (2) it de velops the image twice. Also, fine toner and develop er (smaller particle size) are used. As a result, the image quality, especially of thin lines, the trailing edge of half-tone areas, and black solid areas are improved.

A dc motor is used to drive the development unit. The developer is supplied to th e de velo pe r guide [A] upper side by the

paddle roller [B]. The magnet of the upper develop men t rolle r [ C] attracts the developer to the roller surface.

The doctor blade [D] trims the de veloper to the desired thickness an d crea tes back spill to the cross mixing mechanism [E]. The de velo pe r is transferred to the lower development roller [F] and then retu rne d to the agit at or rolle r [G] area via a paddle roller.

The development rollers are given a positive bias to prevent the toner fro m being attracted to the non-image area s, on the drum surf ace , th at may have a slight residual positive charge . The bias volt ag e is det ermin ed base d on the factors checked by the pro cess control system.

2-38

Upper/Lower Dev. Roller [D]

31 July 1995 DEVELOPMENT

6.2 DRIVE MECHANISM

[G]

[E]

[F]

[A]

[D]

[B]

[C]

A171D606.img

All the development unit parts, except the toner supply brush, are driven by the development drive motor (dc motor).

The toner supply brush is driven by the ton er sup ply motor. The development mot or drive s t he deve lop ment drive gear through two

timing belts. The rotation is transferre d as follows:

Idle Gear [C]

Timing Belt [E]

Toner Mixing Vane

Development Drive Gear [A]

Auger Drive Gear [B]

Drive Gear [F]

Idle Gear

Paddle Roller [G]

Since reversed toner mixing vane rota tion could damage something, a one-way clutch is installed to the mixing vane drive gear.

2-39

DEVELOPMENT 31 July 1995

6.3 CROSS MIXING

[A]

[E]

[C]

[D]

[B]

A171D600.img

This copier uses a standard cross-mixing mechan ism to kee p the toner and developer evenly mixed. It also help s agitate the developer t o pre ven t developer clumps from forming, and help s cre at e th e triboelectric charge.

The developer on the turning upper de velo pment roller is split into two parts by the doctor blade. The part trimmed by the doctor blade goes to the backspill plate [A].

As the developer slides down th e ba ckspill plate to the agitator [ B] , th e mixing vanes [C] move it slightly toward the rear of the unit.

Part of the developer falls into the auger inle t [D] and is transported to the front of the unit by the auger [E].

The agitator moves the developer slightly to the fron t as it tu rns, so the developer stays level in the develop men t un it.

2-40

Drum Current Detection PCB

TRIG 1 (800V)

TRIG 2 (100V)

PWM Sensor

Main PCB

31 July 1995 DEVELOPMENT

6.4 DEVELOPMENT BIAS

6.4.1 Bias Power Pack

Potential Sensor

Bias P.P.

RA2

RA1

Relay

A171D529.wmf

A171D525.wmf

PWM Duty Cycle = t2/t1 x 100 (%) Output = 10 x PWM Duty Cycle (V)

TRIG1 TRIG2 OUTPUT (V)

L H +800

H L +100

L L depends on the PWM signal

HH 0

The bias power pack has three input termina ls. Two of the m are use d as th e output selector as shown in the table . When both terminals are low, the output can be controlled by the other input terminal which receives the PWM signal from the main PCB.

+800 and +100 V are used to calib rate the drum potential se nso r in the process control data initializa tio n.

2-41

DEVELOPMENT 31 July 1995

6.4.2 Bia s Control In Copy Cycle

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

VB = VBB + VBA + VBADJ + VBS (ADS Mode) VB = VBB + VBM (Manua l ID Mode)

1) Base Bias (VBB)

Drum Potential

Dark

Original Density

VBB

Light

A171D528.wmf

As explained in the process control section, the base bias for development is determined by the drum light potential (VL) measured in each original scan. The base bias is also affecte d by th e exposure lamp adjustment setting in the SP mode.

VBB = VL2 + 280 – ∆ V + 10 N – 15 M

∆ V = VL2 – Vr (Maxim um ∆ V = 210, Minimum ∆ V = 110)

NOTE: N = Number of th e lamp adjustment setting in SP mod e.

M = Number of the La tent Image Adj. in SP mo de .

2-42

31 July 1995 DEVELOPMENT

2) ADS Compensation (VBA)

Dark

ADS voltage (V)

Light

A171D524.wmf

According to the original backgro un d density, the bias is compensated. The compensation value is dete rmine d with the volta ge measu red by the ADS sensor (ADS Voltage) as follows:

VBA = – 295 {VADS (A0/A1) – 2.80 } A0: Initial Exposure Sensor Output A1: Current Exposure Sensor Output

If the exposure lamp ou tput is changed, the valu e of VADS is also changed. To compensate for this cha ng e, VADS (A0/A1) is use d inst ea d of VADS.

NOTE: VBA + VBADJ have a limited range fro m 0 V to +260 V.

3) VBADJ

SP setting -7

SP setting +7

VBADJ = 30 M (- 7 ≤ M ≤ + 7)

Darker

ADS Voltage

Light

A171D680.wmf

VBA + VBADJ can be adjusted using SP mode (ADS Sensor Adjustment) to absorb the tolerance of the ADS pattern in the factory. In this mode, VBA + VBADJ can be lowered below 0 V for t est ing in the factory.

NOTE: Do not adjust the setting of VBADJ in the field. Adjust the setting of

VBS in the filed.

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ID Selection

DEVELOPMENT 31 July 1995

4) Manual ID Selection Position Compensa tion (VBM)

120

–60

–120

–180

A171D532.wmf

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

VBM = 60 x M – 240 (When M = 1 to 6)

60 x M – 360 (When M = 7)

NOTE: M = Manual ID selection position. M ranges from 1 (darkest) to 7

(lightest). When manual ID is set to 7 (lightest), th e cha rge coron a outp ut is lowered by 10% PWM duty cycle.

5) SP Mode ID Selection Compensation (V BS)

In the SP mode, the image density level in the ADS mod e can be selected from four steps. The VBS is determined by the SP setting as follows:

Selected level VBS (V)

L +60 N 0 (Default) H –60

VH –120

2-44

VL Pattern

Outside

31 July 1995 DEVELOPMENT

6.4.3 Bia s for the ID Sensor Patte rn

A3/11" x 17"

Lens Position

B4/81/2" x 14"

A4/8

1/2" x 11"

Exposure Glass

A171D530.wmf

ID Sensor Pattern

The lens horizontal position is diffe ren t in th e use d pape r size on this mode . On the other hand, the ID sensor position is fixed at one positio n. Th ere fore, the ID sensor pattern on th e ba ck sid e of the expo sure glass bracket will be positioned on the drum only when B4/81/2" x 14" size paper is used .

The sensor pattern on the drum is made for each paper size as follows (100%):

Paper Size Pattern (Black)

A4/A5/8

1/2" x 11"/51/2" x 81/2" Outside image of exposure glass (no light)

B4/8

1/2" x 14" ID sensor pattern on the exposure glass bracket

A3/11" x 17" Exposure lamp off (no light)

The ID sensor bias (VBP) is determined using the following base voltage in every case.

VBP = –360 + V01

V01, which is explained in the process control section, is used fo r the VBP calculation as the drum pote ntial after the charge coro na value .

The VBP can be changed by the SP mode (Toner Densit y Correct ion). The following compensation will be applied to the above VBP.

Setting LNHVH

(V) –60 0 +60 +120

2-45

Default: H (+60 V)

[B]

TONER DENSITY DETECTION AND SUPPLY 31 July 1995

7. TONER DENSITY DETECTION AND SUPPLY

7.1 TONER SUPPLY MECHANISM

[A]

[B]

[D]

[C]

A171D593.img

The main PCB monitors the ID sensor pattern density on the drum through the ID sensor once every ten copies and turns on the toner su pply mo to r when the pattern density is low (if Vsp/Vsg ≥ 1/13).

The toner supply motor [A] tu rns the to ner su pply ro ller [B ] fo r a certain period based on the paper size and the supply amount set by SP mo de.

A brush roller with low rotation torq ue and that can supp ly large amounts of toner even with low operation spe ed, is u sed for th e tone r supp ly roller.

Toner mixing vanes [C] turn slowly while contacting the inne r wall surfa ce of the toner tank whenever the development mot or is turning. This prevents toner blockages, and sup plies toner to the toner agita to r [ D].

2-46

Start Key

31 July 1995 TONER DENSITY DETECTION AND SUPPLY

7.2 TONER DENSITY DETECTION

7.2.1 ID Sensor Patte rn Production

Main SW ON

Counter A Counter B

Drum sensitivity varies from copy to copy. Especially, drum rest time affe cts drum sensitivity.

To compensate the sensitivity changes in the copy run, the ID sensor development timing and development bias is controlled using two copy counters.

ID Sensor Pattern

Start Key

A171D531.wmf

Counter A: Counts the copy number. Resets when th e Start key is pressed.

Counter B: Counts the copy number. Resets if the accu mulated number is 10 or above when the Start key is pressed, or when the ID sensor pattern is made.

NOTE: Both count ers are reset when the main switch is turned on or the

doors are opened.

The ID sensor pattern is made in the following conditions:

1) At the leading edge of the first copy cycle aft er th e main switch is turned on or when the do ors are ope ne d.

2) If A ≥ 10 At the trailing edge of the copy cycle when; A = 10n (n: any numeric number)

3) If A < 10 When the last copy is finishe d and B ≥ 10, then the pattern is developed at th e lea ding edge of the next copy cycle .

2-47

TONER DENSITY DETECTION AND SUPPLY 31 July 1995

7.2.2 Toner Density Detection

A171D533.wmf

Low image density

Bare drum

Sensor pattern

High image density

A171D534.wmf

The ID sensor measures th e de nsit y of the ID sensor pattern developed on the drum. The main PCB receives two values of the sensor out pu t, the value for the sensor pattern (Vsp ) and the value for the bare drum (Vsg).

Toner will be supplied under the following conditio n:

Vsp/Vsg ≥ 1/13

2-48

31 July 1995 TONER DENSITY DETECTION AND SUPPLY

7.2.3 ID Sensor Abnor ma l Conditi ons

a. Vsp Abnormal

If the measured Vsp is 1.4 V (when Vsg = 4 V) or more and this condition is detected five times in a row, a system error condition will be indicat ed on the CRT and the 7% fixed toner supply control will be used for the rest of the copy run.

b. Vsg Abnormal

If the measured Vsg during ID sensor pattern detection is 2.5 V or less and this condition is detected five times in a row, a system error condition will be indicated on the CRT and the 7% fixed toner supply control will be used for the rest of the copy run.

If both abnormal values return to normal du ring the copy run , th e toner supply control will also be returned to normal.

7.3 TONER SUPPLY AMOUNT

Vsp (V)

(at Vsg = 4.0 V)

0.3 ≤ Vsp < 0.4

0.4 ≤ Vsp < 0.5

0.5 ≤ Vsp

The toner supply ratio is determin ed base d on the supp ly amou nt dat a in SP mode and Vsp values as shown in the above table.

The table shows the amount for the A3 /DL T mode . Whe n smalle r pap er is used, the supply amount becomes half.

The toner supply roller turns for a period based on the selected supply ratio.

Toner Supply Amount Data in SP Mode

15% 30% 45% 60%

7 151530 15 30 45 45 30 45 60 60

2-49

TONER DENSITY DETECTION AND SUPPLY 31 July 1995

7.4 TONER CARTRIDGE

[A]

A171D607.img

[B]

A171D588.img

When the toner cartridge is set, the toner cartridge senso r [A] is de-actua ted. The main PCB monitors the toner cartridge sensor signal and detects if the cartridge is replaced at th e toner end condition. The main PCB inhibits copying if there is no toner cartridge.

The toner cartridge is also used as the use d tone r collect ion tank. The copy image becomes poor if the collected toner is re - used . To prevent accidental re-used of the collected toner, a sprin g pla te lo ck mecha nism [B] is installed. The lock allows the toner cartridge shutter to be pulled and return ed only once.

2-50

[E]

31 July 1995 TONER DENSITY DETECTION AND SUPPLY

7.5 TONER END DETECTION

7.5.1 Toner Near End Detection

[C]

[B]

[A]

[D]

A171D601.img

Toner near end is detected by measu ring physica l amount of toner remaining in the toner tank by the following mechanism.

The toner near end feele r [A] has a magnet [B] and is installed on the toner mixing vane drive shaft [C]. The toner near end sensor [D] is located underneath the to ne r t an k (outside) and has the sensor act uator [E] with a magnet. When the toner tank has enough toner, the toner near end feeler does not lower due to the resistance of toner.

When the remaining to ne r amount in the toner tank become s b elo w approximately 250 grams, the ne ar en d fe ele r lo wers and repulses the sensor actuator by the magnet ’s re pulsion force. This actuates the toner near end sensor. When the main PCB se nse s the ton er ne ar en d sen sor actuation three times in a row, the toner near end con dition is displayed on the CRT screen to let the operator know to replace the toner cartridge. In the toner near end condition, copies can be mad e until th e tone r end is dete cte d by th e ID sensor.

2-51

TONER DENSITY DETECTION AND SUPPLY 31 July 1995

7.5.2 Toner End Detection

When little toner remains in the toner tank, the amou nt of toner su pplied to the development unit decreases, and the image of the ID senso r p at te rn ge ts lighter.

When the Main PCB detects the low ID sensor pattern density con dition (Vsp/Vsg ≥ 1/9) more than three times in a row during the toner near en d condition (physical check), or when main PCB coun ts 2000 or more copies made since the toner near end con dition, the toner end cond ition is displayed on the CRT screen and copying is inhibited until t he ton er cart ridg e is replaced.

Copy

Near End

Yes

Copy from

Near End condition < 2

(N.E~)

Toner End

Yes

Vsp / Vsg ≥ 1/9 3 times

Yes

A171D500.wmf

2-52

31 July 1995 IMAGE TRANSFER AND PAPER SEPARATION

8. IMAGE TRANSFER AND PAPER SEPARATION

8.1 PRE-TRANSFER DISCHARGE

[A]

[B]

A171D605.img

The pre-transfer corona (PTC) [A ] an d pre -tra nsf er lamp (PTL) [B] are used to prevent incomplet e toner transfer and pick-off pa wl ma rks on th e copy.

To prevent incomplete ton er tra nsfer, the PTC reduces drum potentia l by applying an ac corona. The PTC also applies a dc negative charge at the same time to keep the toner potential negative.

The PTL further reduce s the drum po te ntial. Since the PTC gave a negat ive charge not only to the tone r but also to the non image (no toner) are a on the drum, PTL reduces the negative charg e on the drum which may att ract copy paper and cause pick-off pawl marks.

2-53

IMAGE TRANSFER AND PAPER SEPARATION 31 July 1995

8.2 IMAGE TRANSFER

[A]

[B]

A171D595.img

The copy paper is fed from the regist ration section to the tran sfe r a nd separation section through the guide mylar [A] which ho lds th e copy paper so that the paper sticks to the drum surface.

The transfer corona [B] ap plie s a posit ive cha rge from the back side of the copy paper to attract the negatively charged toner image from the drum to the copy paper.

2-54

31 July 1995 IMAGE TRANSFER AND PAPER SEPARATION

8.3 PAPER SEPARATION

[A]

A171D602.img

To break the attractio n be twe en the pap er an d th e drum, the separation corona applies an ac corona to the back side of the paper. The stiffne ss of the paper then causes it to separat e fro m t he drum. The pick-off pawls [A] which are installed on the cleaning unit assist paper separation.

Two corona wires are used to improve separation by widening the discharge area. Also, a larger coron a curre nt is applied at the leading edg e of the pape r for the same purpose.

2-55

IMAGE TRANSFER AND PAPER SEPARATION 31 July 1995

8.4 TC/SC WIRE CLEANER

A171D609.img

The transfer and separation corona unit has the wire cleaners to remove paper dust and/or toner particles which may get on the coron a wires.

Once every 5000 copies, the wire clean ers are activa te d whe n the main switch is on. The hot roller temperature must be less tha n 100°C for the wire cleaner to be activated.

2-56

31 July 1995 IMAGE TRANSFER AND PAPER SEPARATION

8.5 PICK-OFF PAWLS

A171D603.img

[A]

A171D589.img

The pick-off pawls assist the paper separation process. The pick-off pawls are kept normally in conta ct with the drum.

When the transport unit is lowered, the pick off pawls are released from the drum.

The pick-off pawl shaft is cont acted to the cam gear [A] which is locate d at the front side and drive n by th e drum flange gear. The cam gea r gives side-to-side movement to th e pick-off pawl shaft to preven t to ne r f rom accumulating on the pick-off pawls.

2-57

IMAGE TRANSFER AND PAPER SEPARATION 31 July 1995

8.6 TRANSPORT UNIT

A171D608.img

Four transport belts are used to transport the copied pa pe r to the fusing section. The vacuum fan sucks t he air t hro ug h the holes on the transport unit to hold the paper on the transport belts.

The transport unit is pushed up and locke d int o positio n by th e fro nt and rear guide rollers. Turning th e tra nsport unit release lever t o th e lef t releases the lock and lowers the unit to clear paper jams.

If ozone produced by the corona charges stays in the drum a rea , it may cause uneven corona charg ing or affect drum sensitivity causin g po or image problems.

The vacuum fan sucks the ozone through the air duct and transports it to the ozone filter. Ozone is changed to oxygen by the filter and blown outside the copier.

2-58

31 July 1995 CLEANING

9. CLEANING

9.1 OVERVIEW

[B]

[C]

[A]

A171D590.img

This copier uses the counter blade syste m for drum cleaning. The blade is angled against drum rotat ion. This counter blade system has the following advantages:

• Less wearing of the cleaning blade edge.

• High cleaning efficiency.

Due to the high efficie ncy of this cleaning system, the PCC and clea nin g bias are not used for this copier.

The cleaning brush is used to support the cleaning blade. A looped-type brush is used for better efficie ncy. The brush collects toner from the drum surf ace and scra ped by the cleaning blade. The flick bar [A] and th e flick rolle r [B] me cha nica lly re move ton er on the cleaning brush. Tone r is tra nsp orted to the toner cartridge by the ton er collection coil [C].

To remove the accumulated toner at the edge of th e cleaning blade, the dru m turns in reverse for about 20 mm at the end of every copy job. The accumulated toner is removed by the cleaning brush by this action. All the driven gears except the drum drive gear have one-way clutches to prevent reverse rotat ion durin g this operation.

2-59

CLEANING 31 July 1995

9.2 DRIVE MECHANISM

[B]

[A]

[C]

[E]

[G]

[D]

[F]

A171D599.img

The drive force from the main motor is tran smitted to the cleaning unit drive gear via the timing belt [A] an d th e cleaning unit coupling [B ]. The cleaning unit drive gear then transmits the force to th e fro nt side through the cleaning brush [C] and flick roller [D]. The force at th e fro nt side is used for the blade cam gear [E] and toner collection coil gea r [ F].

There is a one-way clutch in the tra nsp ort unit drive gear [G] to prevent the drive parts in the cleaning unit from receiving the reverse rotation force.

2-60

31 July 1995 CLEANING

9.3 CLEANING BLADE PRESSURE MECHANISM

[A]

[B]

[C]

[D]

A171D592.img

When the cleaning sole no id [A ] is e ne rgize d, the solenoid arm lowers the pressure arm [B]. This frees the pre ssure release lever [C] and the blade spring [D] applies pressure to th e cleaning blade.

To ensure cleaning blade op era tion, +38 V is applied to the sole no id fo r 0 .3 seconds as initial activation, then +24 V is applied.

2-61

CLEANING 31 July 1995

9.4 CLEANING BLADE SIDE-TO-SIDE MOVEMENT

[A]

[B]

A171D596.img

The cleaning blade is held on th e clea ning blade holder with a shoulde r screw [A] at its center so that the cleaning pressure is evenly applied to the drum surface.

The cleaning blade holder touches the cam gear [B] which gives a side-to-side movement to th e blade. This movement preven ts th e cleaning blade from being damaged.

2-62

31 July 1995 CLEANING

9.5 TONER COLLECTION MECHANISM

[B]

[A]

A171D597.img

Toner collected by the clea ning unit is transported to the ton er cart ridge through the toner collection tubes. Three helical coils are used for the tone r transport.

A magnetic disk torque limiter [A] is used on the toner collectio n coil drive mechanism to prevent th e coil fro m being damaged by toner clogge d in th e collection tube. The toner collection coil drive gear [B] has two actuat ors fo r the coil overload sensor. The main PCB mon ito rs t he sensor output and display an SC code if no signal changes are det ect ed for more tha n 3 seconds while the development motor is turning.

2-63

CLEANING 31 July 1995

9.6 TONER SCATTERING PREV ENTI O N

[A]

[B]

A171D591.img

The cleaning unit has two air o ut let s covered by the cleaning filter on its back side. The vacuum fan draws th e air fro m t he clean ing unit through the cleaning filters [A] and the toner filter [B] located above the transport section. This prevents the toner in the cleaning unit from be ing scattered to the drum area.

2-64

31 July 1995 CLEANING

9.7 CLEANING SOLENOID CIRCUIT

Main PCB

Scan 2

Cleaning Sol

Scan 2

DC Drive PCB

Interface PCB

Overload Sensor

A171D527.wmf

The main PCB energizes RA301 an d 30 3 fo r 0 .3 secon ds to supply +38 V for the cleaning blade so len oid at the initial solenoid activation. The RA301 and 303 are then turned of f an d +24 V is sup plie d to the cleaning solenoid.

The main PCB sends a pulse signal t o th e coil ove rload sensor through the interface PCB. When the overload sensor is actuated, the pulse signal is returned to the main PCB. The main PCB is monitoring this signal change for toner collection coil blocking.

2-65

CLEANING 31 July 1995

9.8 CLEANING BLADE SOLENOID CONTROL

A171D598.img

Start Key

Cleaning Sol.

[A]

[B]

Main MotorFR

[B]

A171D526.wmf

The main motor turns in reverse fo r 4 0 pulses at the end of every copy job. At this time, the cleaning solen oid is kept on to clean off the to ner o n th e cleaning blade edge. When the drum te mpe rature is more than 49°C [A], the toner on the cleanin g blade edge may soften and clog due to heat. To prevent this, the clea ning blade is released from the drum at the start of the drum reverse rotation. The bla de touches the drum again while drum is still turning in reverse (due to inertia) to clean the edge of the blad e.

The cleaning solenoid off timing [B] is determined based on th e accu mulated number of copies as follows:

Accumulated copy number Off Timing

≥ 100 copies

< 100 copies

15 seconds after the main motor off

5 minutes after the main motor off

This is to minimize toner scattering in the machine. The cleaning solenoid is turne d off when the main switch is off or the front

doors are opened.

2-66

31 July 1995 QUENCHING

10. QUENCHING

[B]

[A]

A171D604.img

To neutralize any charges re main ing on the drum, a cold cathode flu orescent lamp [A] (CFL) is used as the quenchin g device.

When the main PCB sends a trigger signal to the the CFL stabilizer [B] , an ac power (ac 480 V/5 mA) is supplied to the CFL.

2-67

PAPER FEED 31 July 1995

11. PAPER FEED

11.1 OVERVIEW

[E]

[D]

[A] [B]

[C]

A171D535.wmf

A171D536.img

This machine feeds paper from three trays. (Ca pacity: 1st tray [A]: 500, 2nd tray [B]: 500, 3rd tray [C]: 1700).

In addition to the copier paper feed stat ion s, th ere is one LCT ([D] : cap acit y:

3000) feed station also , th e by-pass feed table station [E] is equipped to the

European ARDF/SS version machine Paper is positioned at the center of the trays. This copier uses an FRR (Feed + Reverse Roller) paper feed system which

uses three rollers: pick-up roller, feed roller, and separat ion roller. A slip clutch is used as a torque limiting device for th e separation roller.

One anticondensation switch for all tray heat ers is insta lled on this copie r. A tray heater is installed on each tray and turns on when the anticondensatio n switch is on while the main switch is off.

2-68

[C]

31 July 1995 PAPER FEED

11.2 PAPER FEED AND SEPARATIO N

[A]

[D]

[B]

A171D616.img

While the main motor is rotating, the paper feed clutch gear [A] is being driven from the main motor drive and is always rotatin g. The sep ara tio n rolle r shaft [B] is turning in the directio n ind icat ed by the arrow in th e illust rat ion . The separation roller drive n by th e separation roller shaft is p reve nted from turning in the paper feed direction by the built-in torque limiter [C]. The separation roller uses a frict ion mechanism to overcome the to rque and stop the roller. The separation roller shaft speed is reduced by the low rotatio nal drive ratio of the drive gear [D] ag ain st the feed clutch gear. This reduces the main motor load.

2-69

[D]

PAPER FEED 31 July 1995

[B]

[A]

[C]

[E]

[F]

[G]

A171D623.img

Using the paper feed trigger signal from the main control board the pa per feed clutch [A] turns on and paper fee d rolle r shaf t [B ] be gin s to tu rn. A one-way clutch drives the paper feed roller [C]. The pick-up rolle r [D] rot at es via an idler gear. Then, paper feed begin s. A one-way clutch allows the separation roller shaft to drive at high spee d in the dire ctio n ind icated by the white arrows in the illustration. This is because the hig h rot ation al drive ratio of the drive gear [E] against the feed clutch gear. Howeve r, as th e separation roller [F] rotates in contact with the paper feed roller, the sepa rat ion roller rotates in the directio n of the black arrow.

Paper is fed by the operatio n de scribed above. The paper feed senso r [ G] senses the paper and the pick-up solen oid activates. The pick-up roller is then lifted up to its upper position wh ich is out of the pa pe r pat h. Simultaneously, the paper feed clutch tempo rarily turns of f.

This process of turning off the paper feed clutch as paper reaches t he paper feed sensor is called pre-registration and is necessary due to the high copy speed. The paper waits at that poin t un til th e pro per t ime, and the n the clut ch turns on again to feed the paper to the following transport relay rolle rs.

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31 July 1995 PAPER FEED

11.3 FRR OPERATION

A171D654.img

The direction in which the separa tio n rolle r turns depends on the frictional forces acting on it. The magnetic torque limiter app lies a constant clockwise force [F1]. When there is a single sheet of paper being driven between the rollers, the force of the friction between the feed roller and paper [F2 ] is greater than F1. So, the separa tion roller turns counter clockwise.

If 2 or more sheets are fed between the rollers, the forwa rd fo rce on the second sheet [F3] become s less tha n F1 be cau se the friction between th e two sheets is small. So, the separation roller starts turning clockwise and drives the second sheet back to the tray.

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A171D537.wmf

[F]

PAPER FEED 31 July 1995

11.4 SLIP CLUTCH MECHANISM

[A]

[G] [D]

[B]

[C]

[E]

A171D538.img

The slip clutch [A] consists of the inp ut hub [B] and the out pu t hub [C] which is the case of the clutch as well. The magnetic ring [D] and the steel spacers [E] are fitted onto the input hub. The ferrit e ring [F] is f itt ed into the out put hub. Ferrite powder [G] pa cked between the magnetic ring and the ferrit e ring [F] generates a constant torque due to magn etic force. The input hub and the output hub slip when the rotational force exceeds the constant torque.

This type slip clutch does not require lubrica tion.

2-72

3 mm

31 July 1995 PAPER FEED

11.5 PAPER RETURN MECHANISM

[C]

[A]

[B]

A171D624.img

[C]

[E]

[F]

[D]

A171D633.img

The paper feed clutch [A] turn s on and the pape r fee d rolle r shaf t tu rns in th e direction indicated by the arrow in th e illust ration. The swing lever [B] is raised by spring tension until it contacts the stopper [C] . In this condition, paper fee d be gins.

When the clutch turns off, the swing arm remains in the raised positio n. The separation roller [D] and feed roller [E ] can rotate in the direction of paper return until the swing lever meets the inside stay [F]. Then, the separation roller and feed roller stop rotating. This operation returns paper between the reverse and feed rollers to the tray to prevent paper damage when th e tra y unit is pulled out.

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PAPER FEED 31 July 1995

11.6 PAPER END DETECTION

[B]

[A]

1st, 2nd, and 3rd Trays

A171D617.img

[B]

LCT

A171D615.img

The paper end sensor [A] is installed at the rear of the tra y bottom plate. The paper end condition is detected by the photo -int errupter and feeler [B]. When there is no paper remaining in the tray, the feeler rises from the tra y botto m hole to deactuat e th e ph oto-interrupters f or the LCT, and to actuate the photo-interrupter for the 1st, 2nd, and 3rd Trays.

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[A]

31 July 1995 PAPER FEED

11.7 PAPER VOLUME DETECTIO N

[A]

A171D655.img

Each tray uses a pulse generator [A] to determine the quan tity of paper in the tray. The amount of pape r present is based on the number of pu lses generated between the time the tray starts moving up and the time the uppe r limit sensor turns off.

2-75

[A]

PAPER FEED 31 July 1995

11.8 PAPER TRAY DRIVE MECHANISM

11.8.1 1st, 2nd, and 3rd Trays

[C]

[B]

[E]

[F]

A171D620.img

[D]

1st, 2nd, and 3rd Trays

A171D628.img

[H]

[G]

A171D629.img

Drive from a reversible motor [A] is transmitt ed trou gh a worm gea r [B] to the drive pulley [C] shaft. The tray wires ha ve met al be ads on th em. These bea ds are inserted in the slots at the ends of the tray support bracket [D] of th e bottom plate, so, when the wire pulley turn s (counte rclockwise , rear view), the beads on the wires drive the tray suppo rt bra cket and the tray moves upward. The tray goes up until the upper limit sen sor [E] is actuated by the top sheet pushing up the pick-up roller [ F].

To lower the tray, the pulley turns clockwise until the lower limit senso r [G] is actuated by th e act uator of the bottom plate [H].

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Ricoh FT8982, FT680 Service Manual FT8982

Specifications and Main Features

Frequently Asked Questions

User Manual

PREVENTION OF PHYSICAL INJ URY

HEALTH SAFETY CONDITIONS

OBSERVANCE OF ELECTRICAL SAFETY S TANDARDS