Ricoh 6750, ft6750 Instruction Manual

SECTION 1

OVERALL MACHINE

INFORMATION

30 November 1990

1. SPECIFICATIONS

- Item - - Specifications ­Configuration : Console
Copying Process: Dry electrostatic transfer system
Original: Book/Sheet
Original Size: Maximum A3, 11" x 17"
Reproduction Ratios: 5 reduction ratios, 3 enlarg ement ratios

(One more reduction ratio and
enlargement ratio can be set by SP mode)
zoom :— from 60% to 155% in 1% steps

- A4 Version ­5R: 93%, 82%, 75%, 71%, and 65%
3E: 115%, 12 2%, and 141%

- Letter Version ­5R: 93%, 85%, 77%, 74%, and 65%

3E: 121%, 12 9%, and 155%
Reproduction Ratio Cha nge: Maximum 6.5 seconds
Warm-Up Time: Within 5 minutes (Room Temp. 200C,

680F)
Copy Paper Size: — Maximum A3, 11" x 17"

— Minimum A6, 51/2" x 81/2"

Weight: — 52 g/m2 to 157 g/m2 (14 lb

to 42 lb)

Copying Speed: 52 cpm/11" x 81/2"

53 cpm/A4 sideways

25 cpm/A3, 11" x 17"
First Copy Time: 3.6 seconds (A4 or 81/ 2 " x 11") (LCT feed)
Copy Number Input: Number keys, 1 to 999 (count up or down)

Special Functions:

•

Auto duplexing (3 modes)

•

Margin adjustment (0 to 16 mm [5/8"]

on both sides)

•

Auto image density selection (ADS)

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30 November 1990

•

Automatic paper selection (APS)

•

Automatic reduction/e nla rge ment (AMS)

•

2 single copies mode (Copies facing

pages of a bound original)

•

Cover sheet mode (with ADF or RDH)

Manual Image Density

7 steps
Selection:

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

to 3 minutes or no auto reset.

All functions canceled except cassette

selection. Quantity en te red returns to "1",

and reproduction ratio re tu rns to full size.
Paper Feed:

•

3000 sheet large capacity tray (LCT)

•

Dual 500 sheet universal cassettes

•

Manual feed table
Paper Feed System: Feed and reverse roller
Exposure System: Slit exposure, moving optics
Lens: Through lens, F5, f=215 m m
Light Source:

•

Halogen lamp (85 V, 160 W; control

range 50 to 80 volts RMS)

•

Automatic voltage change (VL Sensor)
Photoconductor: Selenium drum (F-type)
Charge System: Dual wire dc coron a
Erase: LED lamp unit (80 segments)
Development System:

•

Magnetic brush roller

•

Double roller development
Development: Automatic voltage change (The control

board monitors the sele cte d image density

level, drum temperature, and rest time.)
Toner Replenishment: Cartridge exchange (480 g/bottle)
Toner Consumption: 12,000 copies/bottle (7%/A4)
Cleaning System: Blade and brush, pre-cleaning corona
Quenching System: Photo-quenching (cold cathode tube) and

dc corona

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30 November 1990

Image Transfer: Single wire dc corona, pre-transfer lamp
Paper Separation: Dual wire ac corona and pick-off pawls
Image Fusing: Heat and pressure rollers
Fusing Lamp: Halogen lamp (820 W)
Oil Consumption: More tha n 80,0 00 copie s per oil tank

(519 cc)
Electronic Control System: 8-bit microprocessor
Copy Tray Capacity: 250 sheets (all sizes)
Self-diagnostics: 34 codes for the main copie r

8 codes for the finisher
Service Programs: 100 programs controlled from the

operatio n panel
Power Source: 110V/60Hz ⇒ 15A (for Taiwan)

115V/60Hz ⇒ 15A (for N.A.)

220V/50Hz ⇒ 8A (for EU.)

220V/60Hz ⇒ 8A (for EU.)

240V/50Hz ⇒ 8A (for EU.)
Power Consumption

(copier only)

Dimensions:

Weight:

See the following table. Numbers are in

kilowatts per hour.

Warm-up Copying Stand-by Max

0.82 1.26 0.7 1.5

Width Depth Height

Copier only with

platen cover

Full System

(DH, Finisher)

Copier Only 210kg (463lb) 220 kg (485lb)

DF, Sorter 240.5kg (530lb) 250.5 kg (552.3lb)

DH, Finisher 273 kg (601.9lb) 283 kg (623lb)

909mm (35.8") 743mm

(29.3")

1,494 mm

(58.9")

115V version: 220V version:

743mm

(29.3")

1,072 mm

940mm

(37.0")

(42.3")

1-3

14

10

9

7

30 November 1990

2. GUIDE TO COMPONENTS

2.1 INTERNAL & EXTERNAL

5

4

3

2

1

16

6

8

11

12

13

1. Left Door

Open to access the inside of th e
copier.

2. Oil Bottle

Add silicone oil to this bottle.

3. Main Switch

Switches the copier between on
and stand-by condition s.

4. Operation Panel

Operator controls and indicators
are located here.

15

5. Exposure Glass

Position originals here for cop ying .

6. Platen Cover
Lower this cover over originals for
copying.

7. Toner Bottle

Toner is supplied from this bottle.

8. Toner Bottle Holder

Install the toner bottle here.

9. Key Counter Holder

Insert the optional key cou nter here.

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30 November 1990

10. By-pass Feed table

Open to copy on to paper of
non-standard size or weight.

11. Large Capacity Tray

This tray can hold 3,000 sheets of
copy paper. (A4/81/2" x 11"
sideways)

12. Right Door
Open to access the inside of th e
copier.

13. Total Counter

Shows the total number of copies
made.

14. A3/DLT Counter

Shows the total numb er of A3/ DLT
copies made.

15. Cassette Bank

This bank can hold two 500-sheet
cassettes.

16. Paper Cassette

These two cassettes can ho ld
500-sheets of copy paper e ach .

1-5

2

1

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30 November 1990

2.2 OPERATION PANEL

2.2.1 Keys and Indicators for Basic Functions

A4/A3 Version

34567

21 171820 19

16

1. Guidance Indicator

Lights when in guidance mode.

2. Guidance Key

Press to select guidance mod e.

3. Enter Key

Use to enter or change data in
selected modes.

4. Program Indicator

Lights when the copier is in user
program mode.

5. Program key

Press to input or recall user
program.

6. Timer Indicator

Lights when the mach ine has been
turned off by the weekly timer or
automatic shut-off timer.

15

14

12

891011

7. Timer Key

Press to operate the copier after it
has been turned off by the weekly
timer or automatic shut-off timer.

8. Clear Modes Key

Press to clear the copier of
previously entered settings and
modes.

9. Start Key

Press to start copying.

10. Interrupt key

Press to make interrupt copies
during a copy run.

11. Interrupt Indicator

Lights when interrupt mo de is
selected.

12. Clear/Stop Key

Press to cancel the copy number.
While copying press to stop
copying.

1-6

LT/DLT Version

2

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30 November 1990

34567

21 171820 19

16

13. Decimal Point Key

Use to input data for selected
modes.

14. Number Keys

Use to enter the desired number of
copies. They are also used to en te r
data for selected modes.

15.Auto Image Density Key

Press to select/cancel aut oma tic
image density mode.

16. Manual Image Density Keys

Use to cancel automatic control and
manually select the image density
level.

15

14

12

11

910

8

17. Auto Paper Select Key

Press to select/cance l aut o pa pe r
select mode.

18. Select Cassette Key

Press to select a cassette for paper
feed.

19. Full Size Key

Press to make the copy image s the
same size as these of the orig ina ls.

20. Enlarge Key
Press to make enlarged copies.

21. Reduce Key

Press to make reduced cop ies.

1-7

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30 November 1990

2.2.2 Keys and Indicator for Special/Optional Functions

A4/A3 Version

56

7

8

910111213

4

3

14

1

2

1. Staple Key

Press to select one of three staple
modes. (Optional recycling
document handler and finisher are
required.)

2. Staple Indicators

Show which staple mode is
selected.

3. Sorter Key

Press to select sort or stack mode.
(Optional sorter, or finishe r and
recycling document handler are
required.)

4. Stack Indicator

Lights when in stack mode.

5. Sort Indicator

Lights when in sort mode.

6. Duplex Indicators

Show which duplex mode is
selected.

22

23 21

7. Duplex Key

Press to select one of three duplex
modes.

8. Margin Adjustment Indicator

Lights when margin adjust men t
mode is selected.

9. Margin Adjustment Key

Press to set the margin on copy.

10. Centering lndicator

Lights when cente ring mode is
selected.

11. Centering Key

Press to vertically center an original
image on a copy.

12. Size Magnification Indicator

Lights when size magnificat ion
mode is selected.

20

19

18

16

15

1-8

LT/DLT version

3

4

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30 November 1990

8

910111213 14

12

13. Size Magnification Key

Press to select size magnification
mode.

14. Zoom Up Key

Press to increase the rep rod uction
ratio in 1% steps.

15. Zoom Down Key

Press to reduce the reproduction
ratio in 1% steps.

16. Auto Reduce/Enlarge Key

Press to select auto reduce /enlarge
mode.

17. Auto Reduce/Enlarge
Indicator

Lights when auto redu ce/enlarge
mode is selected.

18. Edit Image Key

Press to select one of three edit
image modes.

22

23 21

20

19

17

151618

19. Edit Image Indicators

Show which edit image mode is
selected.

20. Series Copies Key

Press to make copies from book
originals or 2-sided originals.

21. Series Copies Indicators

Show which series copies mode is
selected.

22. Cover Insertion Key

Press to select cover insertion
mode. (Optional document feeder
and sorter, or recycling document
handler and finisher are require d. )

23. Cover Insertion Indicators

Show which cover insertion mode is
selected.

1-9

15

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30 November 1990

2.2.3 Indicator Screen

A4/A3 version

1234 5678910111213 14

1. Full Size Indicator

Lights when full size mode is se­lected.

2. Auto Paper Select Indicator

Lights when auto pap er sele ct
mode is selected.

3. Auto Reduce/Enlarge Indicator

Lights when auto redu ce/enlarge
mode is selected.

4. Paper Size Indicators
Show the size and direction of the
paper.

5. Paper Volume Indicators

When the amount of paper remain­ing in cassettes.

6, Used Toner Bottle Indicator

Lights when the use d toner bottle is
full. Call your service representative.

16

181920212223

7. Add Toner Indicator

Blinks when it is time to change the
toner bottle. When it is continuously
lit, the copier cannot be used until a
new bottle is installed.

8. Add Staple Indicator

Lights when the staple cartridge
runs out of staples.

9. Add Oil Indicator

Lights when the silicone oil level
gets too low. Add silicone oil to the
bottle.

10. Check Paper Path Indicator

Lights if there is a misfeed within
the machine.

11. Load Paper Indicator

Lights when the cassette or tray in
use runs out of paper.

1-10

LT/DLT version

15

17

18

1234 56

7

91011

8

12 1314

1920212223

30 November 1990

16

12. Copy Cycle Indicator

Displays the stage of the copy cycle
in progress.

13. Ready Indicator

Lights when the mach ine is ready to
make copies.

14. Wait Indicator

Lights when the mach ine is not
ready to copy.

15. Call Service Indicator

Lights when there is a funct ional
problem within the machine . Call
your service representative .

16. Copy Counter

(Upper) Displays the number of
copies entered.
(Lower) While copying, it sho ws the
number of copies made.

17. Auto Image Density Indica tor

Lights when the copier is
automatically controlling the image
density.

18. By-pass Feed Indicator

Lights when the by-pass feed table
is open.

19. Manual Image Density
Indicator

Shows the manually selected image
density.

20. Misfeed Location Display

Shows the location(s) of misfed
paper.

21. Magnification Ratio Indicator

Shows the selected rep rod uction
ratio.

22. Zoom Indicator

Lights when in zoom mode.

23. Special Features Indic ator

Lights when special/optional
function is selected.

1-11

DEVELOPMENT

30 November 1990

3. COPY PROCESSES AROUND THE DRUM

EXPOSURE

DRUM CHARGE

QUENCHING

CLEANING

PRE-CLEANING

PAPER SEPARATION

ERASE

PRE-TRANSFER
LAMP (PTL)

IMAGE TRANSFER

DRUM CHARGE
In the dark, the charge corona unit gives a uniform positive charge to the

selenium drum. The charge rema ins on the surface of the drum because the
photo conductive seleniu m has ele ctrical resistance in the dark.

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 elect rical
latent image on the drum surface.

ERASE
The erase lamp illuminates the areas of th e cha rge d dru m su rfa ce th at will

not be used for the copy image. The resistance of the drum in the illuminated
areas drops and the charge on those areas dissipates.

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30 November 1990

DEVELOPMENT
Negatively charged toner is attract ed to the positive ly charg ed area s of the

drum, thus developing the late nt image . (The negat ive tu rbo electric charge is
caused by friction between the carrier and toner pa rticle s.)

PRE-TRANSFER LAMP (PTL)
The PTL illuminates the drum to remove all positive charge from the exposed

areas of the drum. This prevents th e tone r particles from being reattracted to
the drum surface during paper separation and makes paper separation
easier.

IMAGE TRANSFER
Paper is fed to the drum surface at the prop er time so as to align the copy

paper and the develope d image on the drum surface. Then, a stron g po sitive
charge is applied to the back side of the copy pape r, pro viding 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 surfa ce.

PAPER SEPARATI ON
A strong ac corona discharge is applied to the back side of the cop y pap er,

reducing the positive cha rge on the copy paper and breakin g th e electrical
attraction betwee n the paper and the drum. Then, th e stiffness of the copy
paper causes it to separate fro m the drum surf ace . The pick-off pawls help to
separate paper which has low stiffness.

PRE-CLEANING
The pre-cleaning corona (PCC) a pplies an ac coron a with a negat ive bia s to

the drum. This removes the positive cha rge from the drum and makes the
negative charge on the toner remaining on the dru m even .

CLEANING
The cleaning brush remo ves most of the toner on the drum and loosens the

remainder. Then, the bias roller, which has a positive potential, attracts the
toner particles from the cleaning brush to keep it clean. Finally, th e clea nin g
blade scrapes off th e loosened toner.

QUENCHING
The pre-quenching corona applies a positive corona cha rge to th e selenium

drum to eliminate any negative charge remainin g from t he pre-cle aning
corona. Then, light fro m the quench ing lamp electrically neutralizes the drum .

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30 November 1990

4. COPY CYCLE

RDH/ARDF

Lamp Stabilizer

Power Pack

PQC/CB

Finisher/Sorter

Sort

Stack

Staple

Q/PTL

QL (Cathode Tube)

Cleaning Unit

Pre-Cleaning
Corona

Power

Pack-PCC

Fusing Unit

Image

Fusing

Power Pack

PQC/CB

Pre-Quenching
Charge Unit

Cleaning

Transport Unit

Power Pack-C/B

Charge Corona Unit

Drum Charge

Quenching

PCC

Paper

Separation

Paper

Transport

Separation Corona

Exposure

Image

Transfer

Transfer Corona

Erase

Development

Toner Density

Detection

PTL

Original

Feed-in

Optics Assembly

ID Sensor Pattern
VL sensor Pattern

Erase Lamp Unit

Development Unit

Image Density
Sensor

PTL

(Cold Cathode Tube)

Registration

Registration Roller

Original

Stacking

Original

Positioning

Original

Auto-ID Sensor

Power Pack-C/B

Toner Supply
Mechanism

Lamp Stabilizer

Q/PTL

1st

Paper Feed

Original

Feed-out

Original

Density

Detection

Original
Inversion

Manual

Feed Table

Large
Capacity
Tray

Inverter
Mechanism

Inversion

Duplex Transport Unit

Duplex

Transport

Fork Gate Unit

Power Pack-T/S

Delivery Tray

Duplex

Stacking

1-14

Jogger Unit

Duplex Paper

Feed

Cassette Bank

2nd

Paper Feed

3rd

Paper Feed

Cassette

Cassette

30 November 1990

5. MECHANICAL COMPONENT LAYOUT

3

2

1

28

27

26

4

5 6 7 8109

11 12 13 14 15

16

17
18
19
20

21

22

23

24

1. Inverter Unit

2. Third Mirror

3. Second Mirror

4. First Mirror

5. Exposure Lamp

6. Fusing Unit

7. Transport Unit

8. Lens

9. Cleaning Unit

10. Quenching Unit

11. Charge Corona Unit

12. Drum

13. Toner Shield Glass

14. Sixth Mirror

25

15. Erase Lamp Unit

16. Fourth Mirror

17. Fifth Mirror

18. Toner Tank

19. Manual Feed Table

20. Development Unit

21. Large Capacity Tray

22. T/ S Corona Unit

23. Jogger Unit

24. Third Cassette

25. Second Cassette

26. Duplex Delivery Tray

27. Fork Gate Unit

28. Duplex Transport Unit

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30 November 1990

6. DRIVE LAYOUT

26

25

24

23

22

27

3

4

2

1

5 6

7

8

9

10

11

12

13

21

20

19

1. Development Drive Belt

2. Development Drive Gear

3. Development Motor

4. Drum Drive Pulley

5. Drum Drive Belt

6. Main Motor

7. Fusing/Duplex Drive Gear

8. Main drive Belt

9. Exit relay Roller Drive Sprocket

10. Inverter Roller Drive Gear

11. Exit Roller Drive Gear

12. Exit Drive Chain

13. Pulse Generator Drive Pulley

18

14

17

16

14. Registration Roller Drive Belt

15. Cleaning Drive Gear

16. Registration Clutch

17. 3rd Paper Feed Drive Gear

18. Cassette Bank Drive Belt

19. LCT Bottom Plate Drive Belt

20. LCT Motor

21. Duplex Paper Feed Clutch

22. LCT Bottom Plate Drive Chains

23. Relay Roller Clutch

24. Paper Feed Drive Chain

25. Paper Feed Motor

26. 1st Paper Feed Clutch

27. Toner Supply Clutch

15

1-16

21

30 November 1990

7. ELECTRICAL COMPONENT LAYOUT

23

22

1

20

19

5

4

3

2

18

6

7

8

9

10

11

12

13

14

17

1. Fusing Lamp

2. Fusing Thermistor

3. Thermofuse

4. Fusing Exhaust Fan Motor

5. Exposure Lamp

6. Optics Thermoswitch

7. Anticondensation Heater

8. Cleaning Heater

9. Charge Fan Motor

10. Cleaning Thermoswitch

11. Cooling Blower Motor

12. Development Cooling Fan Motor

13. Vacuum Fan Motor

15

16

14. LCT Down Switch

15. Total Counter

16. Drum Heater

17. SC Cleaner Motor

18. SC Cleaner Home Position
Sensor

19. CC Cleaner Motor

20. CC Cleaner Home Position
Sensor

21. Printer Connector (RS232C)

22. Oil End Se nsor

23. Main switch

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30 November 1990

25

26

27

28

29

30

31

32

55

54
53

52

51

50

24

49

48

47

46

45

33

34
35

36

37

38
39

40

41

42

43

44

24. 4th and 5th Mirror Drive Motor

25. Junction Gate Sol.

26. Lens Drive Motor

27. Inverter Pressure Sol.

28. Main Motor

29. Pick-off Sol.

30. Registration MC

31. Paper Feed Motor

32. Development Motor

33. Toner Supply MC

34. Scanner Drive Motor

35. 1st Paper Feed MC

36. 1st Pick-up Sol.

37. Manual Feed Pick-up Sol.

38. 1st Feed Relay MC

39. Duplex Paper Feed MC

40. Cassette Bank Drive Motor

41. LCT Motor

42. Duplex Positioning Roller Sol.

43. Jogger Motor

44. Duplex Stopper Sol.

45. 2nd Feed Relay MC

46. 3rd Paper Feed MC

47. 2nd Paper Feed MC

48. 3rd Pick-up Sol.

49. 3rd Lift Motor

50. 2nd Pick-up Sol.

51. 2nd Lift Motor

52. Duplex Pick-up Sol.

53. Cleaning Sol.

54. Fork Gate Sol. 2

55. Fork Gate Sol. 1

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30 November 1990

85

84

83

82

81

86

80

56

57

58

59

60

61

62

63

64

65

66

67

68

69
70

71
72

79

78

56. Power Pack-CC/Bias

57. Power Pack-PQC/Cleaning
Bias

58. Erase Lamp

59. Bias Thermister

60. Drum Thermister

61. Registration Sensor

62. Operation Panel PCB

63. Image Density Sensor PCB

64. Pre-transter Lamp

65. Quenching Lamp

66. PTL/QL Stabilizer

67. Fusing Cooling Fan

68. Power Pack-PCC

69. Main Motor PCB

70. Optics PCB

77

73

74

75

76

71. Main PCB

72. AC Drive PCB

73. Memory Board

74. Circuit Breaker

75. Noise Filter

76. Main Transformer

77. Power Relay

78. Condition Relay

79. DC Power Supply PCB

80. Cassette Bank PCB

81. SSR PCB

82. Power Pack-T/S

83. Toner Overflow Sensor

84. Paper Feed PCB

85. Development Motor PCB

86. Paper Feed Motor PCB

1-19

105

30 November 1990

90

89

88

87

126

125

124
123

122

121

120

119

118

117

116

115

114

113

112

87. Original Width Sensor

88. Original Length Sensor

89. Auto Density Sensor

90. Fork Gate Unit Safety Switch

91. Lens Home Position Sensor

92. Scanner Home Position Sensor

93. Scanner VL Position Sensor

94. 4th/5th Mirror Home
Position Sensor

95. Duplex Entrance Sensor

96. Toner End Sensor

97. 1st Lift Sensor

98. Jogger Home Position Sensor

99. 1st Relay Sensor

100. LCT Cover Sensor

101. LCT Cover Switch

102. 1st Paper Volume

103. LCT Lower Limit Sensor

104. Paper Position Sensor

105. LCT Lower Limit Safety Switch

91

92

93

94

95

96

97

98

99

104

106

107

108

109

110

111

106. 3rd Relay Sensor

107. 2nd Paper Volume Sensor

108. 3rd Paper Volume Sensor

109. 3rd Paper End Sensor

110. 2nd Paper End Sensor

111. 3rd Paper Size Sensor

112. 2nd Paper Size Sensor

113. 2nd Relay Sensor

114. Manu al Fee d Sensor

115. 3rd Lift Sensor

116. 2nd Lift Sensor

117. 1st Paper End Sensor

118. Manual Paper End Sensor

119. Duplex Paper Sensor

120. Pulse Generator

121. Transport Unit Safety Swit ch

122. Front Door Safety Switch

123. Exit Sensor

124. Fusing Exit Sensor

125. Exit Relay Sensor

126. Inverter Exit Sensor

100

101

102

103

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30 November 1990

8. ELECTRICAL COMPONENT DESCRIPTIONS

MOTORS

NAME FUNCTION LOCATION
Main Drives the main unit components. 28
Development Drives the development unit. 32
Paper Feed Drives the feed sectio n. 31
Development
Cooling Fan
Fusing Exhaust
Fan
Fusing Cooling Removes heat from around the fusing unit. 67
Cooling Blower Prevents build up of hot air in the optics

Vacuum Fan Provides suction so paper is held firmly on

Scanner Drive Drives the scanner. (dc servo) 34
Lens Drive Positions the lens. (dc stepper) 26
4th / 5th Mirror
Drive
Jogger Drives the jogger plates to keep paper

Cleaner Motors Clean charge and separation wires. 17, 19
Charge Fan Ensures even charge on the surface of the

LCT Rises and lowers the LCT bottom plate.

Cassette Bank
Drive
Lift Motors Lift paper to the appropriate feed position. 49, 51

Blows air to the developme nt unit bottom
plate.
Removes heat from around th e fu sing unit. 4

cavity.

the transport belt.

Positions the 4th/5t h mirror assembly. (dc
stepper)

evenly stacked on the duple x t ray.

drum.

(ac motor)
Drives the 2nd/3rd paper feed sections. 40

12

11

13

24

43

9

41

MAGNETIC CLUTCHES

NAME FUNCTION LOCATION
Registration Drives the reg istra tio n rolle r 30
Paper Feed
Clutches
Feed Relay
Clutches
Duplex Paper
Feed
Toner Supply Drives toner supply roller. 33

Starts paper feed from each feed stat ion. 35, 96, 47

Drives the relay rollers. 38, 45

Feeds paper from the duplex tray. 39

1-21

30 November 1990

SOLENOIDS

NAME FUNCTION LOCATION
Cleaning Moves the clean ing blade against the drum. 53
Pick-off Moves the pick-off pawls against the drum. 29
Junction Gate Energizes to direct copies to the duple x tray. 25
Fork Gate
Solenoids

In unison, open and close the appropriate
fork gates according to pap er size.

54, 55

Duplex Pick-up Start s fee d from duplex an d aids the

stopper solenoid.

Duplex

Lowers positioning roller. 42
Positioning
Inverter Pressure Controls the inverter pressure roller. 27
Duplex Stopper Stops copy in the jogger unit. 44
Pick-up

Picks paper up from each feed sta tio n. 36, 48, 50
Solenoids
Manual Feed
Pick-up

Raises the pick-up roller when paper is fed

from the manual feed table.

52

37

SWITCHES

NAME FUNCTION LOCATION
Main Supplies power to the copier. 23
Front Door Safety Cuts ac power line. 122
Transport Unit

Cuts 24-volt lines. 121
Safety
Fork Gate Unit

Cuts 24-volt lines. 90
Safety
LCT Lower Limit

Cuts the signal line of the tray down. 105
Safety
LCT Down Lowers the LCT bottom plate. 14
LCT Cover Cuts power to the LCT when LCT cover is

101

opened.

SENSORS

NAME FUNCTION LOCATION
Pulse Generator Supplies timing pulses to the main board. 120
Exit Detects misfeeds. 123
Exit Relay Detects misfeeds. 125
Oil End Detects the low oil condition. 22
Toner Overflow Det ect s when the used ton er bo tt le is full. 83
Toner End Detects when it is time to add toner. 96
Registration Detects misfeeds. 61

1-22

30 November 1990

NAME FUNCTION LOCATION
Manual Feed Detects when the manual feed table is open. 114
Scanner Home
Position
Lens Home
Position
4th/5th Mirror
Home Position
Paper Size

Informs the CPU when the scanner is at the

92
home position.
Informs the CPU when the lens is at the full

91
size position.
Informs the CPU when the 4th / 5th mirror

94
assembly is at the full size position.
Detects the paper size in the cassette. 111, 112

Sensors
Paper End
Sensors
Scanner VL
Position

Informs the CPU when the copy paper runs
out.
Informs the CPU when the scanner reaches
the VL pattern sensing position.

109, 110,

117

93

Relay Sensors Detects misfeeds. 99, 106,

113
Jogger Home
Position
Duplex Paper Detects whether or not paper is in the

Informs the CPU when the jogger plates are
at the home position.

98

119

duplex tray.
Duplex Entrance Misfeed detector 95
Auto Density Senses the background density of the

89

original.
Original Width Detects the original width. 87
Original Length Detects the original length. 88
Charge Cleaner
Home Position

Informs the CPU when the charge wire

cleaner has reached home po sitio n.

18, 20

Sensors
Manual Feed
Paper End

Informs the CPU that there is no paper in

the manual feed tray.

118

Fusing Exit Detects misfeeds. 124
Inverter Exit Detects misfeeds. 126
Lift Sensors Detects whether paper has been raised to

the proper paper feed position.
LCT Cover Informs the CPU when the LCT cover is

97, 115,

116
100

closed.
LCT Lower Limit Informs the CPU when the LCt bottom plate

103

reaches the lower limit position.
Paper Position Detects the paper position. 104
Paper Volume Detects the amount of paper in

LCT/cassettes.

102, 107,

108

1-23

30 November 1990

THERMISTORS

NAME FUNCTION LOCATION

Drum Monitors the temp era tu re around the drum

and controls the rest-time comp ensation.

Bias Monitors the temperature aroun d the drum

and controls developmen t rest time bia s
compensation.

Fusing Monitors the fusing temperature and turns

the fusing lamp on/off.

POWER PACKS/STABILIZER

NAME FUNCTION LOCATION
Power Pack - T/S Provides high voltage for th e T/S coronas. 82
Power Pack ­CC/Bias
Power Pack ­PQC/Cleaning
Power Pack ­PCC

Provides high voltage for the charge corona
and the development roller bias.
Provides high voltage for the quenching
corona and the cleaning bias roller.
Provides high voltage for the pre-cleaning
corona.

PTL/QL Stabilizer Provides high voltage for the quenching

and pre-transfer lamps.

60

59

2

56

57

68

66

HEATERS

NAME FUNCTION LOCATION

Drum Warms the drum when the main switch is

off.

Cleaning Warms the cleaning section when the main

switch is off.

Anticondensation Prevents moisture from forming on the

optics.

THERMOSWITCHES

NAME FUNCTION LOCATIO N

Optics Provides overheat protection in the optics

unit.

Cleaning Provides overheat pro te ctio n in the

cleaning unit.

16

8

7

6

10

1-24

30 November 1990

LAMPS

NAME FUNCTION LOCATION

Exposure Applies high intensity light to the original for

exposure.
Fusing Provides heat to the fusing unit. 1
Erase Discharges the drum outside the image

58

area. Erases lead/trail edge.
Quenching Neutralizes any charge remaining on the

65

drum surface after cleaning.
Pre-transfer Reduces charge on the drum surface

64

before transfer.

PRINTED CIRCUIT BOARDS

NAME FUNCTION LOCATION

Main Controls all copier functions both directly

71

and through other PCB s.
Optics Controls the speed of the scanner, the

70
position of the lens, and the position of the
mirrors.

Operation Panel Contro ls the LED mat rix, and mon ito rs the

62
key matrix.

Main Motor Controls the speed of the main motor. 69
Development
Motor
Paper Feed Motor Controls the speed of the paper feed drive

Controls the speed of the development
motor.

85

86
motor.

Paper Feed Interfaces with overall pap er fe ed ; rece ives

84
input from paper size and paper end
sensors.

DC Power Supply Rectifies 100 Vac input and outputs dc

79
voltages.

Image Density Detects the density of the image on the

63
drum.

Cassette Bank Interfaces with overa ll cassette bank drive. 80
AC Drive Drives the exposure lamp and the fusing

72
lamp.

Memory Controls weekly timer and memory

73
functions.

SSR Switches the LCT bottom plate up/down 81

5

1-25

30 November 1990

OTHERS

NAME FUNCTION LOCATION

Circuit Breaker G uards against voltage surges in the input

power.
Main Transformer Steps down the wall voltage to 100 Vac. 76
Thermofuse Provides back-up overheat protection in the

fusing unit.
Total Counter Keeps track of the total number of cop ies

made.
Power Relay Controls main power. 77
Condition Relay Controls the heaters on/off. 78
Noise Filter Removes electrical noise. 75
Printer Connector Used for connection to the printer

(RS 232C serial interface).

74

3

15

21

1-26

9. OVERALL MACHINE CONTROL

30 November 1990

Pulse Generator

Sensors

-Toner Overflow

-Exit

-Inverter Exit

-Duplex entrance

-Duplex Paper

-Jogger H.P.

-Toner End

-Oil End

-Image Density

Solenoids

-Fork Gate

-Inverter Return

-Junction Gate

-Duplex Positioning

-Duplex Stopper

-Duplex Pick-up

-Pick-off

-Cleaning

Magnetic Clutches

-Duplex Paper Feed

-Toner Supply

Motors

-Jogger

-Vacuum Fan

-Fusing Exhaust

-Charge Fan

-Development
Cooling Fan

-Ozon Fan

Counters

-Total

-Key

-A3/LDG

Erase Lamp
Power Packs

-PQC/Cleaning Bias

-CC/Development
Blas

Quenching Lamp
Stabilizer

ARDF/Sorter
RDH/Finisher
Menu Sheet Reader
RS232C Interface

Main PCB

Optics PCB

Main Motor

Development

Motor PCB

Paper Feed

Motor PCB

AC Drive

Operation

Panel PCB

Paper Feed

Casstte Bank

(2nd/3rd Feed)

PCB

PCB

PCB

PCB

Motors

-Scanner Drive

-Lens Drive

-4th/5th Mirror Drive

-CC Cleaner Motor

-SC Cleaner Motor
Sensors

-Scanner Home Position

-Scanner Overrun

-Lens H.P.

-4th/5th Mirror H.P.

-CC Cleaner H.P.

-SC Cleaner H.P.

Main Motor

Development

Motor

Paper Feed

Motor

Exposure Lamp
Fusing Lamp

Sensors

-Registration

-1st Relay

-Manual Feed

-Manual Feed Paper End

-Paper End

-Lift

-Paper Volume
Solenoids

-Manual Feed

-Pick-up
Magnetic Clutch

-Paper Feed

-Relay
Sensors

-Paper End (2)

-Paper Volume (2)

-Paper Size (2)

-Lift Relay (2)
Moters

-Lift (2)

Solenoids

-Pick-up (2)
Magnetic Clutch

-Paper Feed (2)

-Relay

1-27

30 November 1990

10. AC AND DC POWER DISTRI BUTI ON

AC Power

Main Motor PCB
Dev. Motor PCB

Paper Feed Motor

Optics PCB

Main PCB
Paper Feed PCB

Clutches
Motors
Solenoids
Counters
Relays

Operation Panel

Power Packs

Erase Unit

PCB

PCB

5V (VC)

24V (VM)

24V (VA)

24V (VP)

DC
Power
Supply

5V (VC)

24V (VF)

24V (VA)

AC Drive

PCB

Cassette Bank
(2nd /3rd Feed)

ARDF/RDF

Finisher

Sorter

Menu Reader

Transformer

Fusing Lamp

Exp Lamp

Drum Heater

Anticondensation

Heater

Cleaning Heater

The illustration on this page shows the electrical power dist ribution in block
form.

AC power (115/220 volts) is supplied from the wall outlet directly to the fusing
lamp and the step-down tran sfo rmer. The transformer supplies 100 volts ac
to the power supply unit, the ac drive board , the pa per ban k (2nd /3 rd pa per
feed station)and sorter.

The power supply unit produ ces fo ur 24 volts an d on e 5 volt s t o operate the
PCB’s, the clutches, the moto rs, the solenoids, the counters, th e rela ys, the
power packs and the era se unit.

1-28

SECTION 2

SECTIONAL DESCRIPTION

30 November 1990

1. DRUM

1.1 SELENIUM DRUM CHARACTERISTICS

Selenium has the following charact erist ics:

• Accepts a high positive electrical charge in the dark. (The ele ctrical

resistance of selenium is high in the abse nce of ligh t.)

• Dissipates the electrical charge when exposed to lig ht. (Exposure to light

greatly enhances the condu ctivit y of sele nium.)

• Dissipates the electrical charge in direct proportion to the intensit y of the

light.
That is, where stronger light is direct ed to the selenium surface, a smaller
voltage remains on the selenium.

The sensitivity of selenium chan ge s slight ly wit h varia tions in the surface
temperature of the drum. (Unde r cool con ditions, the drum conductivity
decreases. This will result in background or excessive image density.) As a
countermeasure, the development bias is change d to compensate for
temperature varia tio ns around the drum. Also, while the copie r is of f, the
drum heater warms the drum.

Drum sensitivity also depends on how long the drum has rested between
copy runs. The copier’s CPU compe nsa te s fo r cha ng es in dru m sensitivity
due to rest time by changing the deve lop men t bia s. This prevents variations
in image density at the beginning of copy runs.

The selenium drum used in th is mode l has hig h sen sitivity, good color
reproduction, and good rep rod uction of low contrast originals (pen cil
originals, etc.)

2-1

30 November 1990

1.2 DRUM HEATER CONTROL

AC Power

Transformer

100VAC

Thermo

Switch

Drum Heater

Anticondensation

Heater

Cleaning Heater

RA2

Main Switch

The drum heater receives 100 volts ac only when the main switch is turned
off. When the main switch is turned on, the 100 volt ac current stop s flowin g.

2-2

2. DRUM CHARGE

2.1 OVERVIEW

[B]

30 November 1990

[A]

[C]

[D]

This copier uses a dual wire corotron un it and a highly sensitive selenium
drum. The corona wires [A] generate a flow of positive ions when the charge
power pack applies a high positive volt ag e to the coron a unit. The drum
coating [B] receive s a unif orm po sitive charge as it rotates past the corona
unit.

The charge fan [C] provides a smooth flow of air to the interior of the charge
corona unit [D] to prevent un eve n build up of positive ions. (An uneven build
up of positive ions could cause uneven image density.)

2-3

30 November 1990

2.2 WIRE CLEANER

[B]

[A]

[B]

[A]

[D]

[C]

Paper dust or toner particles on the coron a wires [A ] may interfere with
charging. The wire cleaner [B] corrects this problem by automatically wiping
the charge corona wires clean. Pa ds on the wire clean er bra cket clean the
corona wires as the dc motor [C] drives th e cleaner bracket from the home
position to the rear e nd of th e coro na unit and the n back a gain.

Operation of the wire cleane r is based on copy coun t. A RAM co unter keeps
track of the number of copies made since the last time the wires were
cleaned. The CPU checks this counte r each time th e cop ier is turn ed on. If
the count is greater than 5,000 at that time , th e CPU tu rns on the clean er
motor to clean the coro na wire s. Simu ltaneously, it resets the count er to zero.
During a cleaning cycle, the clea ne r motor drives the wire cleaner toward the
rear endblock. After 30 seconds, the motor reverses to drive the wire cleaner
to the home position. Normally, the cleaner reache s the rear en dblock in
about 10 seconds, but th e mot or stays on for 20 seconds to ensure that the
cleaner moves the full distan ce. Th e mot or turns off when the cleaner
activates the home position sensor [D].

2-4

2.3 WIRE CLEANER MOTOR

30 November 1990

Optics PCB

C

P

U

Driver

Driver

( 5)

( 5)

( 5)

( 5)

( 5)

( 5)

CN306-1

CN306-4

CN306-5

CN306-6

CN306-7

CN306-2

REV

FWD

REV

FWD

5V(Vc)

CC

Cleaner

H.P.

Sensor

C C

M

SC

M

5V(Vc)

SC

Cleaner

H.P.

Sensor

Small dc motor in the corona fron t end block drives the corona wire cleaner.
When a cleaner motor is energized, the CPU supplies forward drive for 30

seconds from CN306-4. Then , it reve rses th e po larit y of the motor drive
voltage to return the coron a wire clea ne r to th e ho me position (CN306-5).
When the home position senso r t urn s o n, the CN306 -1 dro ps to zero and it
stops.

This mechanism is used also for the sepa rat ion corona wire cleaner.
If the home position sensor is not activate d with in 20 secon ds af te r reverse

drive is initiated, the CPU stops the moto r and adds 1 to the cou nt er stored in
SP mode 121. Copies can still be made and there is n o service call indica tion
on the opera tio n panel.

SP #121 SC 85: C.C. Home Position Sensor does not turns on .

SC 86: C.C. Home Position Sensor do es not turns off.
SC 87: S.C. Home Position Sensor does not turns on.
SC 88: S.C. Home Position Sensor does not turns off.

2-5

30 November 1990

2.4 CHARGE CORONA POWER PACK

+24V(Vp)

Front Door Safety SW

CC/Bias P.P

CN1-1

CN1-5

DC/DC
Converter

Main PCB

Charge( 5)

5V DC

CN2-3

CN102-B18

CN2-5

TC/SC P.P.

( 24)

P-GND

CN1-2

CN1-1

The circuit operation for the charge corona begins with the input of +5 volts
(Vc) at CN2-3. This voltage powers the LED of the photocoupler.

Additionally, 24 volts (Vp) enters the power pack at CN1-1. This po wer sup ply
is used to produce the high vo lta ge corona. This voltage is interrupt ed if the
front door safety switch opens.

The charge corona turns on 543 milliseconds before the registration MC is
turned on. A LOW signal from the CP U (CN101 -B1 8) is sent to the CC/B
power pack through the TC/SC po wer pa ck.

The OFF timing of the charg e coro na powe r pack varies according to the
paper size being used.

2-6

3. OPTICS

3.1 OVERVIEW

30 November 1990

[C]

[B]

[A]

[D]

[I]

During the copy cycle, an image of the origin al is refle cted onto the surface of
the drum [I] via the optics assembly. The op tics asse mbly con sists of the
following parts:

1. First Scanner [A]:
Exposure lamp [B] (85 V, 160 W )
First mirror
AD (Auto Density) sensor fiber optics cable [C]

2. Second Scanne r [ D]:
Second mirror
Third mirror

3. Lens (F5, f = 215 mm) [E]

[E]

[F]

[G]

[H]

4. Fourth and Fifth Mirror Assembly [F]:
Fourth Mirror
Fifth Mirror

5. Sixth Mirror [G]:

6. Toner Shield Glass [H]

2-7

30 November 1990

This copier has nine stand ard reproduction ratios: five red uctions, three
enlargements and full size. In additio n, it has a zoom fun ctio n. The
reproduction ratio can be selected in one percent ste ps fro m 60% to 15 5% .

A servomotor drives the first and secon d scanners during the copy cycle.
This motor is controlled by the opt ics PCB, which changes the motor speed
depending on the reproduction ratio. Two stepper motors chan ge the posit ion
of the lens and the fourth and fifth mirror assembly to change the
reproduction ratio. The sixth mirror is fixe d.

The fiber optic cable used for the auto density sensor (ADS) is mounted on
the first scanner. The ADS collects ligh t ref lected from the original in auto
density sensing mode.

2-8

3.2 EXPOSURE LAMP CONTROL

Optics PCB

E

Feed back signal

CPU

24V

C

B

0V

0V

Trigger Pulse

CN303-2

CN303-1

CN303-4

CN303-3

CN304-4

CN303-9

CN501-2

CN501-1

CN501-4

CN501-3

CN501-9

CN501-6

AC Drive PCB

Zero
Cross
Detect

Lamp
Monitor

Lamp Control

CN503-1

CN503-2

A

CN503-3

CN503-5

D

30 November 1990

Front
Door
Safety
Switch

RA1

AC (N)

AC (H)

TH. Switch

Exposure Lamp

AC power
Zero cross
Trigger pulse
Lamp power

Feedback
signal

A

B

C

D

E

Feedback

The optics board controls and mon ito rs t he expo sure lamp circuit, instead of
the main board. The ac drive board receives 100 volts ac from the
transformer [A] and it is used for th e zero cross signal, which is sent to the
optics board [B]. The optics board sends the lamp trigger pulses to the ac
drive board from CN303-9 [C]. This lamp trig ger pulse activa te s the triac on
the ac drive board, which provides th e ac power to the exposure lamp [D].

The voltage applied to the expo sure lamp is also provided to the lamp
monitor circuit, which rectif ies and smoothes it.

The main CPU monitors the lowe st po int of th is smoot he d wave (f eedb ack
signal) which is directly proport ion al to the actu al lamp voltage, and then
changes the timing of th e trig ge r pulse in response to the feed ba ck volta ge .

If the lamp voltage is too low, the main CPU sends the trigger pulse earlier,
so that more ac power can be app lied to th e exposure lamp. This feedback
control is performed instantly; so the lamp voltage is always stable even
under fluctuating as power conditions.

The voltage applied to the expo sure lamp can be changed with SP mo de #48
and displayed with sp mode #5 1.

2-9

30 November 1990

3.3 SCANNER DRIVE

[D]

[B]

[A]

[E]

This model uses a dc servomotor [A ] to drive the first [B] and second [C]
scanners.

[C]

This first scanner is attached to the scanner drive wire by the wire clamp [D].
The second scanner is connected to the scanner drive wire by a movable
pulley [E] (the second scanner pulley).

The second scanner pulley move s the second scanner at half the velocity of
the first scanner. This maintains th e focal distance between the original and
the lens during scanning. This rela tio nship can be expressed as follows:

V1r = 2(V2r) = VD/r
where r: Reproduction

V1r: First Scanner Velocity (when the Reproduction ratio is "r")
V2r: Second Scanner Velocity (when the Reproduction ratio is "r")
VD: Drum Peripheral Velo city (30 0 mm/s)

The first scanner wire clamp also actuat es the home position sensor. The
CPU on the optics board controls both the registration and return timing.

2-10

3.4 SCANNER MOTOR CONTROL

Scanner Home Sensor

24V(VM)

30 November 1990

M-GND

Timing Pulse

Reset

5V(VC)

C-GND

Main PCB

CN307-1

CN302-5
CN302-4
CN302-7

CN302-3
CN302-2

CN302-8
CN302-9

5V

TXD

RXD

LE

S/R
RST

-2

-3

Optics CPU

Speed data

CN304-1

F

R

Optics PCB

Driver

Timer IC

PWM

CN304-2

E-A
E-B

CN308-1

CN308-3

CN301-1

CN301-2

CN301-3

CN301-4

Scanner drive

M

The scanner drive motor is a dc servomoto r. The CPU o n the op tics bo ard
controls the speed of this servomotor. The main CPU and the optics CPU
communicate through a serial interf ace bus (TXD/ RXD).

Encoder

After the main CPU sends the scann er sta rt signal to the optics CPU, the
optics CPU receives the drum speed data from the main PCB (pulse
generator).

An encoder on the servomotor has two magn et ic senso rs t hat ge nerate two
pulse signals. The optics CPU monit ors th e scan ne r spee d an d dire ctio n by
these pulse signals.

Based on the drum speed and encoder data, the optics CPU determines the
proper speed for the scan ner drive motor to obtain proper vertical
magnification. The optics CPU sends the spe ed data to the timer IC, which
controls the scanner moto r circu it.

The home position sensor informs the optics board when the first scanner is
in the home position.

2-11

30 November 1990

3.5 LENS/MIRROR POSI TI O NING

[C]

[D]

[B]

[A]

Lens Drive

The lens drive motor (stepper mot or) [A ] cha ng es th e len s posit ion according
to the selected reproduction ratio to provide the prop er ho rizontal
magnification between the lens an d the dru m’s surface.

The output gear of the lens drive motor en gage s the gears [B] of th e lens
drive pulley. The lens drive wire [C] is wrapped around the lens drive pulley
and is connected to the lens drive bracket [D]. The rotation of the lens drive
pulley moves the lens back and forth in discrete steps.

2-12

Lens Positioning

[A]

30 November 1990

[C]

[B]

[D]

[A] Lens Drive Pulley
[B] Lens Housing

The lens home position senso r [C] informs the optics PCB when the lens [D]
is at the full-size position (home position). The optics PCB determines the
lens stop position in reduct ion and enlargement modes by counting the
number of steps from the home position. When the repro duction ratio is
changed, the lens move s directly to the selected magnif icat ion position.

2-13

30 November 1990

Operation

Panel

PCB

TXD/RXD

Main PCB

Home position is checked by
moving the lens from the
enlargement side towa rds the
reduction side. So, whe n ho me
position is checked, a LO W to
HIGH to LOW signal is present
at CN307-5 of the optics board.
This occurs when the actua to r
blade enters and exits the lens
home position sensor. The lens
only references home posit ion
when going to full size (at powe r
up, when modes are cleared,
when full size is selected.) The
lens always overshoots the
selected magnification ratio
position by 40 steps to eliminate
mechanical play when go ing
from enlargement to reduction.

RXD

TXD

Optics

CPU

Reduction

Optics PCB

Driver

5V(VC)

( 5)

Home Position (100%)

40pls

40pls

40pls

24V(VM)

CN305-2
CN305-3

CN305-4
CN305-5
CN305-1.6

CN307-1

CN307-5

CN307-2

M-GND

Lens motor

M

24V(VA)

Lens H.P. sensor

Enlargement

2-14

3.6 FOURTH AND FIFTH MIRROR ASSEMBLY

[E]

[F]

30 November 1990

[B]

[D]

[C]

[A]

When the reproduction rat io is chan ged, the stepper motor [A] moves the
fourth and fifth mirror assembly [B ] usin g the wire [C] and pulleys [D]. This
provides the proper focal distance between the original and the drum.

When the fourth and fifth mirror assembly is in the full-size position, the
actuator [E] on the assembly actuates the fourth/fifth mirro r home posit ion
sensor [F]. This signal goes to the optics CPU.

2-15

30 November 1990

Fourth and Fifth Mirror Assembly Positioning

Optics PCB

Operation

PCB

TXD/RXDPanel

Main PCB

RXD

TXD

Optics

CPU

Driver

24V(VM)

CN305-8
CN305-9

CN305-10
CN305-11

M-GND

CN305-7,12

24V(VM)

M

Mirror
Motor

High

Power up

Home
Position

Signal

Low (Reduction/Enlargenent)

40pls

100% Mag Ratio

(Home Position)

Power up

100%

40pls

Away from H.P.

Reduction

Towards H.P.

( 5)

5V

CN307-1

CN307-6

CN307-2

Mirror
Sensor

The mirror home position sensor informs the optics CPU when the fourt h and
fifth mirror assembly is at the home positio n. The ho me po sitio n is
determined by a LOW to HIGH to LOW change on CN307-6 of the optics
board.

When a reproduction rat io is se lect ed , the operation panel PCB sen ds th is
information to the main board. The main board th en send s the app rop riat e
trigger signals through the serial line to the optics board.

When moving away from the home posit ion, the mirror drive pulley turns
clockwise and moves directly to the sele cte d po sitio n. However, when
moving towards the home position (pulley turns counterclockwise), the mirror
assembly overshoots the selected position once and th en returns to the
selected position. This ta kes out an y mechanical play.

2-16

30 November 1990

3.7 ORIGINAL SIZE DETECTION IN PLATE N MODE

[A]

[B]

There are seven reflective sen sors in the optics cavity for the original size
detection. Two of the m a re use d for sensing the original wid th [A] and the
other five sense the original len gt h [B ].

While the main switch is on, these sensors are active and the origin al size
data is always sent to the main cpu. Howe ver, the main CPU che cks the dat a
only twice when in platen mode.

2-17

30 November 1990

1st Check

[A]

15 cm

15cm

2nd Check

P3 P4 P5 P6 P7

1st

Original Length

Sensor

ONONONONOFFONOFFONOFF

2nd

ON

First check is done when the pla te n po sition sensor [A] turns on. This is when
the platen is positioned about 15 cm above the expo sure glass. At th is time,
only the sensor(s) locate d unde rneath the original receive the reflected light
and are on. Other sensor(s) a re of f. Through the on/off data of th e seven
sensors, the main CPU can reco gn ize th e orig inal size.

Second check is done when th e platen cover is closed. (The plate n cover
switch is on.) This is to confirm that the original size detected at the first
check is correct. At the check, all senso rs shou ld be on becau se of the white
color of the platen shee t. This d ou ble check prevents mis-detection of the
original size due to a black solid area being positioned just above a sensor.

In case the copy is made with the open plat en condition, the main CPU
decides the origina l size only th rough the data when the Print key is p resse d.
No second check can be perf orme d.

This original size detection method eliminat es the necessit y for a pre -scan
and increases the machine ’s prod uctivity.

2-18

3.8 VL DETECTION

Vsl ≈ 2.0

30 November 1990

[E]

Vsg ≈ 4.0

A: VL Position Sensor
B: VL Pattern
C: Right Scale
D: ID Sensor
E: VL Pattern Image

[D]

[C]

[B]

[A]

In order to compensate for cha ng es in th e cop y image density cau sed by
dirty optics, the main CPU checks the image density of the VL pattern when
the main switch is turned on. This is done only when the fusin g temperature
is lower than 100 °C.

After the machine idles for 30 seconds, the scanner moves un til the scanner
VL position sensor [A] tu rns on . The VL pattern [B] is located un de rne at h th e
right scale [C], about 30 mm from the scanner fu ll-return position. (At this
time, the lens also moves in th e red uction direction to prevent the scanner
guide from striking the lens.) Then, the VL patt ern is exposed.

The ID sensor [D] checks the reflectivity of the VL patt ern ima ge and the ID
sensor pattern image [E ] on the drum surf ace in the same way. The CPU
receives two voltage values dire ctly from the ID sensor: the value for t he bare
drum (Vsg) and the value for the pattern image (Vsl). The main CPU stores
Vdat (Vdat = Vsl/Vsg) in memory an d comp are s it with the VL reference
value (Vref). Vref was sto red in memory by SP mode #67 at machine
installation when the light intensity was adjusted.

2-19

30 November 1990

(Vref Setting: SP mod e #6 7)
When SP mode #67 is set, the scann er move s t o th e VL pat te rn po sitio n. The

main CPU collects both Vsl and Vsg data and store s t hese values in memory
as the VL reference (Vref = Vsl/ Vsg ). This Vre f is st ore d in memo ry unt il the
next Vref setting is performed.

NOTE: P erform Vref setting after adju stin g the ligh t intensity or Vsg.

When the Vdat value is monitore d, a fixed bias (80 volts) is app lied to th e
development rollers; however, when Vref is set by SP mode #67, the
development bias is automatically shifted to 50 volts. This 30 volt differen ce
corresponds to one half step of the manual ID level.

If Vdat is less than Vref, th e exposure lamp voltage is increase d 2 volts. If
Vdat is greater than Vref, the volta ge is decrea sed 1 volt.

Vref ≥ Vdat Dark copy image (2 volts is incr ea se d.)
Vref < Vdat Light copy image (1 volt is decreased.)

At VL detection, the scan ne r moves to the VL sen sor position two times: The
first scan checks Vsl and Vsg for VL det ect ion and the second scan monitors
changes in the exposure lamp ligh t int en sity fo r ADS compensation.

2-20

4. ERASE

30 November 1990

El

A

B

Lo

Lc

Es

ON
OFF
ON

Es

g

4.1 OVERVIEW

A: Lead Edge Erase Margin
B: Side Margins --- 2 ± 2 mm each (For full-size copies the total of

both side margins is less than 4 mm.)
Lo: Original Image Width
Lc: Charged Width on the Drum
El: Lead Edge Erase
Es: Side Erase
R: Paper Lead Edge Registration --- 0 ± 2 mm
A+R: Lead Edge Blank Margin --- 3.5 ± 2.5 mm

The erase unit consists of a PCB with 10 registe rs a nd a row of 80 LEDs
mounted in a plastic casing. The LEDs emit light in the yellow-gre en part of
the spectrum.

The erase lamp performs th e fo llowing functions: lead ed ge erase, side
erase, trail edge erase, ima ge dens ity pa tt ern [g], and the editing fu nct ions.
Trail edge erase begins after the trailing edge of the copy paper; therefore,
the trailing edge will not appear on the copy.

2-21

30 November 1990

4.2 LEAD EDGE AND TRAILING EDGE ERASE

The entire bank of erase lamp s turns on to erase the drum before and after
the image area. Leading edge erase overlaps the paper an d the image
slightly. The leading edge marg in he lps pre ven t fusing jams by making it
easier for the stripper pawls to separate the paper from the hot roller. Trailing
edge erase turns on about 2 mm after the trailing edge of the copy paper.

The width of the lead edg e marg in can be ad just ed by SP mod e #4 1.

Mode No. Function Data

41 Lead Edge

Erase Margin

Adjustment

During image density detection cycles (once eve ry ten cycles), th e cen ter
block of erase lamps turns of f lon g en ou gh for th e sensor pattern to be devel­oped [g].

Adjusts the

lead edge

margin

0 - 15 8

Factory

Setting

Comments

0.6mm per
step (max.

-4.8mm to
+4.2mm)

4.3 SIDE ERASE

Side erase overlaps the imag e sligh tly on eith er side . The CP U calcula tes the
side erase margins from the pap er size and the selected reproduction ratio.
As the paper is fed to the cen te r o f th e dru m , th e LEDs for side erase turn on
in pairs. The erase lamp is not used for side era se with A3 or 11 x 17 paper.
For these paper sizes, side erase occurs due to the end block covers of the
charge corona.

The CPU adjusts the side erase margin to be as near as possible to th e
actual image size, even wh en using the zoom function. Howe ver, since the
erase lamp LEDs will not work in precise one millimeter int erva ls, the side
erase margin varies slightly depend ing on th e rep rod uction ratio.

SP 27 increase the side margin s by 5 mm.
Also, the position of the entire erase lamp unit can be adjusted by turning an

adjustment screw at th e rear side of the unit.
This adjustment is neccessary wh en the side era se margins are uneven.

2-22

4.4 EDGE ERASE FUNCTION

Edqe

Paper

size

A3
11"

B4

10"

8-1/2"

A4

8"
B5
A5

5-1/2"

B6

A6

Erase

1-3

78-80

1-6

78-80

74-80

1-13

68-80

1-15

66-80

1-16

65-80

1-20

61-80

1-26

55-80

1-27

54-80

1-28

53-80

1-30

51-80

1

80

1-7

5 mm
(0.2")

) 3.5mm

)4.7
)3.5
)4.5
)3

)5
)4.1

)3.5

)4
)4.85
)4

)2.5

79 -80

77-80

1-8

73-80

1-8

73-80

1-15

66-80

1-17

64-80

1-18

63-80

1-22

59-80

1-27

54-80

1-28

53-80

1-29

52-80

1-31

50-80

1-2

1-4

10 mm

(0.4")

)8.5mm
)9.7

)11
)9.5
)8
)10
)9.1

)8.5

)9
)9.85
)9
)7.5

1-3

78-80

1-6

75-80

1-9

72-80

1-10
71-80

1-17

64-80
1-19

62-80

1-20
61-80

1-24

57-80
1-28

53-80

1-29

52-80

1-30

51-80

1-32

49-80

15 mm

(0.6")

)13.5mm
)14.7

)13.5
)14.5

)13

)15
)14.1

)13.5
)14
)14.85

)14

)12.5

30 November 1990

20 mm

(0.8")

1-4

)18.5mm

77-80

1-8

)22.2

73-80

1-11

)18.5

70-80

1-12

)19.5

69-80

1-19

)18

62-80

1-21

)20

60-80

1-22

)19.1

59-80

1-26

)21

55-80

1-29

)19

52-80

1-30

)19.85

51-80

1-31

)19

50-80

1-33

)17.5

48-80

The edge erase function erases a border around the copy. The border is
adjustable in 4 steps using SP mode #38. These borders are approximately
5, 10, 15, and 20 millimeters wide, but vary slightly according to paper size
and the selected repro duction ratio. The table shows the ON/OFF condition
of the erase lamp LEDs for the various paper sizes. The factory setting is 10
millimeters.

2-23

30 November 1990

4.5 ERASE LAMP CIRCUIT

LED

23456

IC 1

GND SI L R CK E VCC SO

78

9

LED

10 11 12

GND SI L R CK E VCC SO

CN37-F
CN37-6
CN37-A
CN37-1
CN37-5
CN37-2
CN37-3

CN37-4

IC 2

13

14

5V(VC)
C-GND
CLOCK

ENABLE
LATCH

ERASE DATA

15 16

B-GND
5V(VB)

73

LED

GND SI L R CK E VCC

CN102-B1
CN102-A16
CN102-B17

CN102-B18
CN102-A18

CN102-A17

This copier uses 80 LEDs in the era se lamp unit. The large number of LEDs
allows precise control of the side erase margins.

Shift register drivers contro l the LEDs. Init ially, the ENAB LE signal (LOW
active) sets all shift registers t o OFF. Th en the main board sends ERASE
DATA to the shift registers fro m CN1 02-A17.

74 75 76 77 78 79 80

IC 10

ERASE UNIT

MAIN BOARD PCB

After the ENABLE sign al goes ba ck to HIG H, th e shift registers start
accepting data. The dat a bit fo r LE D 1 is set at each CLOCK pulse. If the
data line is HIGH at the time of the CLOCK pulse, the shift regist er is set to
turn the LED on; if it is LOW, the shift register is set to keep the LED off. The
data in the shift registers is shifted right one positio n each clock pulse; so, it
takes 80 CLOCK pulses to set the shift registers for all the LE Ds.

After all data bits have been sent, th e main boa rd sen ds th e LATCH sig nal to
turn on the erase lamp unit. Simultaneously, the shift registers turn on all
LEDs for which data bits have been set.

To turn off the erase lamp unit, the ENABLE signal is reset to LOW.

2-24

5. DEVELOPMENT

5.1 OVERVIEW

[D]

[E]

30 November 1990

[C]

This copier uses a double roller develop men t (DRD) system. This system
differs from single roller develo pment system in that (1) it develop s the image
in a narrower area, (2) it develops the image twice, and (3) the relative speed
of each development roller ag ain st the drum is reduced. Also, finer toner and
developer (smaller particle size) are used . Both DRD system and new
supplies improve the image, especially of thin horizont al line s, th e tra iling
edges of the half-tone areas, and black cross points.

When the main board sends the trigg er sign al to the development motor
PCB, the development mot or (dc motor) is energized. When it turns on, the
agitators [A], paddle roller [B] and two development rollers [C] start turning.
The paddle roller picks up developer in it s paddles and transports it to the
lower development roller. Internal permanent magnets in the development
rollers attract the develo pe r to th e development roller sleeve. The turning
sleeve of the lower deve lop ment roller carries the developer t o th e up pe r
development roller. The upper de velo pment roller carries the developer past
the doctor blade [D]. The do cto r b lad e trims the developer to the desired
thickness and creates backsp ill to th e cross mixing me cha nism.
The development rollers con tin ue to turn, carrying the developer to the
selenium drum [E]. When the developer brush contacts the drum surface, the
positively charged areas of the drum surface attract and hold the negatively
charged toner. In th is wa y, th e latent image is developed.

[A]

The development roller is given a posit ive bia s to pre ven t the toner from
being attracted to the non-imag e are as on the drum surf ace that may have a
slight residual positive charge.

After turning another 100 degrees, the developer is released to the
development unit.

2-25

30 November 1990

5.2 DRIVE MECHANISM

[B]

[C]

[A]

[A]: Development Drive Ge ar
[B]: Auger Gear
[C]: Development Roller Gears

The gears of the develop ment unit and the toner agit at or ge ar are driven by
the development drive gear [A] when the development motor turns. The
rotation is transmitted as follows:

[A] ⇒ [B] ⇒ [C]

The above gears are helical gears. Helical gears are more quiet than normal
gears. The teeth of the de velo pment drive gear are chamfere d so th at they
smoothly engage with the develo pment roller gears [C] when the unit is
installed.

2-26

5.3 CROSSMIXING

[E]

[C]

30 November 1990

[A]

[D]

[B]

[F]

[B]

[D]

[A]

[E]

[C]

[F]

This copier uses a standard cross-mixing mechanism to keep the toner and
developer evenly mixed . It also he lps ag ita te the developer to prevent
developer clumps from forming and help s creat e th e turbo electric charge.

The developer on the tu rning development roller is split int o two parts by the
doctor blade [A]. The part tha t stays on the development roller [B] forms the
magnetic brush and develops the latent image on the drum. The part that is
trimmed off by the doctor blade goes to the backspill plate [C].

As the developer slides down the backspill plate to the agit ator [D], the mixing
vanes [E] move it slightly to ward the rear of the unit. Part of the developer
falls into the auger inlet and is transp ort ed to the fro nt of the unit by th e auge r
[F].

The agitator moves th e de velo pe r slig ht ly t o th e fro nt as it turns, so the
developer stays level in th e de velo pment unit.

2-27

30 November 1990

5.4 IMAGE DENSITY CONTROL

Image density is contro lled in two ways: 1) by changing the streng th of th e
bias voltage applied to the develop ment roller sleeve, and 2) by changing the
strength of the volta ge app lied to th e exposure lamp.

Applying a bias voltage to the development sleeve reduce s the pot en tia l
between the develo pment roller and the drum, which redu ces the amount of
toner transferred; so, the stronger the bia s volta ge , the lighter the copy
image. Similarly, increasing th e volt ag e to the expo sure lamp causes an
increase in light intensity, which also results in lighter copies.

The control method is dif fe rent depending on whether the image density is
selected manually or the automatic ID system is used .

Manual Image Density Control

LIGHT<--------------------------------------------------------------> DARK

ID Level 7 6 5 4 3 2 1
V1:Bias 350 320 290 290 260 260 260
V2: Lamp
Voltage

Vo+4.5 Vo+3.5 Vo+2.5 Vo V o– 1 Vo–3.5 Vo–5

Vo = 50 to 80 volts ac
When image density is set manually, the de velo pment bias (base level) and

the exposure lamp voltag e vary as shown in the above table. The lamp
voltage at ID level 4 (Vo) can be adjust ed wit h SP mode #48.

2-28

Auto Image Density Control

Leading edge of original

30 November 1990

14 mm

Exposure Lamp

36 mm

Fiber Optic Cable

When automatic image density cont rol is se lect ed , the exp osure lamp voltage
is set at position 4. Image density is contro lled only by cha ng ing the bias
voltage.

At the start of the copy cycle the original sensing mechan ism measures the
background density of the origin al imag e. It does this by measuring the
strength of the light reflected fro m a 36 mm strip. This strip sta rts 14 mm from
the leading edge of the original. A fiber optic cable pipes the reflected light to
a photodiode on th e main board. The photod iod e is t he inpu t element of the
auto ID circuit.

2-29

30 November 1990

500

400

Bias Voltage

(V1)

300

200

530

500

470

440

410

380

350

320

290

Auto
ID
Input
Voltage

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Auto ID Peak Hold Input Voltage

Leading edge of original

14 mm

Forward scan

36 mm

Peak hold

Auto ID data

Vod/Vod (ref.)

The CPU checks the voltage output by the auto ID circuit. This circuit ha s a
peak hold function. The peak hold volt ag e corre spo nd s to the maximu m
reflectivity of the origina l. Based on the peak hold voltage, the CPU
determines the proper bias ba se leve l and send s a 5 -bit con tro l sig nal t o th e
power pack. The power pack then applie s the prop er bia s to th e de velo pment
roller.

During ADS 1 voltage adjust ment at SP mode #56, the scanner moves to the
VL pattern position aft er the volt ag e is aut oma tica lly se t to 3.0 volts at the
pure white original. At this time, the main CPU checks the reflected light from
the VL pattern through the fib er op tic cab le an d kee ps this va lue in memory
as the Vsl reference fo r the ADS. At the second scan of every VL det ect ion,
the main CPU also monitors th e Vsl da ta through the fiber optic cable an d
compare it with the Vsl referen ce da ta .

If the Vsl data voltage diff ers fro m it s refe rence, the main CPU compensates
the ADS reference voltage automatically.

2-30

30 November 1990

Bias Compensation Factors

As discussed previously, the bia s base level is set either by the automatic
image density system or by the operator through the image density keys. The
CPU increases the base bias level as ne cessa ry t o compen sat e for the rest
time between copy runs and the drum temperature, both of which affect drum
sensitivity.

1) Rest Time Compensation

10 ∼ 20°C

# of copies

Rest Time

0 ∼ 3 min
3 ∼ 50 min
50 min ∼ 2 hr

123

Same as previous copy
3030000
30 30 30 0 0

Copies

4 ∼ 56 ∼ 10

>2 hr 60 3 0 30 30 0

20 ∼ 45°C

# of copies

Rest Time

0 ∼ 10 sec
10 sec ∼ 3 min
3 ∼ 50 min
50 min ∼ 2 hr

123

Same as previous copy
30 30 30 0 0
60 60 30 30 0
90 60 60 30 30

Copies

4 ∼ 56 ∼ 10

>2 hr 12090906030

Note: Figures are in + Vdc.

The drum sensitivity often drops slightly ove r the first few cycles of a cop y
run. This is because the light fro m t he expo sure lamp fatigues the drum
slightly, and it takes a few co pie s f or th e selenium to restabilize. The amo un t
that the sensitivity drops depen ds on the rest time between copy runs (the
longer the rest time, the greate r the change . Se e above tab le).

The time at which each copy cycle is completed is stored in RAM. The CPU
references this time data in RA M to dete rmine the proper rest time bias
compensation leve l fo r th e ne xt copy cycle even after the main switch ha s
been turned OFF and ON after a copy cycle.

2-31

45°C

30 November 1990

The copier increases the bias at the beginning of each copy run to prevent
variations in the image density of the first few copies produced.

If the drum temperature is less than 10°Celsiu s, no rest time compe nsation is
applied.

2) Drum Temperature Compensation
The CC/Bias power pack monitors drum tempera tu re th rou gh a thermisto r

(TH-1). The power pack increases or d ecre ase s the bias volt ag e to
compensate for variatio ns in drum sensitivity that are induced by tempe rat ure
changes in the drum cavity. At 30°Celsius (base temperature), no drum
temperature compen sat ion is perfo rmed. For each 1°C rise in drum
temperature, the deve lop ment bias is decreased 6V. For each 1C fall in drum
temperature, the deve lop men t bia s is incre ase d 6V until 1 5°C. Belo w 15°C,
the development bia s is incre ase d 14 V for each 1°C fall.

Bias
[V]

100

90

0

–90

–100

15°C 30°C

2-32

Bias For ID Sensing

30 November 1990

500

400

Bias
(Vt)

300

200

100

Scanner On

Development
Bias

1st Copy

I.D. Check

290 290

1234567891011

260 260 260 260 260 260 260 260

* Auto ID
* Rest Time 5 Min
* Drum Temp 30 C

Copy Cycle

40ms

290ms

ID Sensor Pattern For Image

o

Forward Scan

(Selected Bias)

11th Copy
I.D. Check

In order to develop the ID senso r pat te rn con sistently, the CPU applies a
fixed base bias level to the de velopment roller at the beginn ing of the first
copy after power-up , an d then once every ten copy cycles. Fixed base bias is
factory set at 470 volts dc (a dju sted by SP #33). Compensation for drum
cavity temperature and drum rest time is added to the fixe d base bia s.

The CPU applies the ID sensor fixed base bias to the deve lopment roller
about 40 milliseconds before the scanner starts forward scan. Just afte r the
sensor pattern is deve loped, the CPU changes the bias out pu t to the level
selected by the ID keys or auto ID system. The bias output remains at this
level until the scanner start s the re tu rn scan .

Toner concentrat ion can be in crea sed or decreased by changing the ID fixed
base bias. Higher fixed base bias will cause the sensor pattern to be
developed lighter. The CPU th en senses that the toner level is low and
therefore adds more tone r. This resu lts in da rker cop ies as to ne r
concentration is increased.

SP #33 0 1 2 3
ID fixed base bias: 470V 380V 440V 500V

2-33

30 November 1990

5.5 BIAS CONTROL CIRCUIT

Drum

Thermistor

5Vc

ID Sensor

Board

CN2-6

CN101

-A2

CN102-B8

TC/SC P.P

Bias 5[ 5]
[ 24]PQC/

PTL Trigger

Bias 4[ 5]

Bias 3[ 5]

Bias 2[ 5]

Bias 1[ 5]

Main PCB

+5V(Vc)

CN1-3

CN1-11

CN1-4

CN101-A18

CN1-10

CN101-B19

CN1-9

CN101-A19

CN1-8

CN101-B20

CN1-7

CN101-A20

CN1-6

CN1-1

CC/Bias P.P

DC/DC

Converter

+24V

GND

CN1-2

Thermistor

CN1-12

Output

B

C

Front Door
Safety Switch

Bias

5Vc

TH1

ID Sensor

Board

+24V(Vp)

The CPU sends a bias trigger sign al th rou gh the TC/ SC power pa ck to tu rn
on the developer bias power pack. The main board also monitors the
selected image density level and the copie r re st time , an d it sen ds a 5- bit
bias output control signal to the bias power pack to control the bias output
according to the image density level position and the copier’s rest time. (See
the table on the following page.)

After receiving the 5-bit signa l, th e po wer pa ck out puts the proper bias
voltage. This voltage is furthe r compe nsated by the bias thermistor on the ID
sensor board.

The bias voltage for ID Sensor Pattern (Vb (sp)) and the actual bias voltage
(Vb) is displayed on the guidance display with SP mode #59. The displayed
value does not include the compensation factor of the bias thermistor (drum
temperature compen sat ion ).

2-34

5-Bit Bias Control Signal

BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 Bias Output

00000 50
00001 80
00010 110
00011 140
00100 170
00101 200
00110 230
00111 260
01000 290
01001 320
01010 350
01011 380
01100 410
01101 440
01110 470
01111 500
10000 530
10001 560
10010 590
10011 620
10100 650
10101 680
10110 710

30 November 1990

NOTE: SP34 shifts the bias und er all con ditions. There are four sett ings: 0,

60, 120, and – 60

2-35

[E]

30 November 1990

6. TONER DENSITY DETECTION AND SUPPLY

6.1 TONER SUPPLY

[A]

[D]

The toner supply drive gear [A ] turns when the developme nt motor is on. The
toner supply clutch [B] applie s t he rotation from the toner supply drive gear t o
the toner supply roller gear [C], wh ich drive s the agit at or gear [D]. Toner
catches in the grooves on the tone r supp ly roller [E ]. Then, as the grooves
turn past the openin g, the ton er dro ps into the development unit .

The teeth on both the toner supply drive gear and the toner supply roller gear
are chamfered.

[C]

[B]

2-36

6.2 BOTTLE DRIVE MECHANISM

[G]

[D]

[B]

30 November 1990

[C]

[A]

[E]

[F]

For easy access, the toner bot tle is just inside the fron t cove r. The bot tle is
positioned horizontally.

The bottle drive mechanism tra nsp orts toner from the bottle to the toner tan k.
A worm gear [A] on the front end of the toner supply roller [B] drives this
mechanism.

When the toner supply roller turns, the worm gear turns th e toner bot tle [C]
via the worm wheel, the bott le drive gear, and the bottle gear. The toner
bottle has a spiral groove that helps move toner to th e to ne r in let .

To prevent toner from sca tt ering when the toner bottle is lowered, a rack [D]
and pinion [E] system closes the toner shutter [F].

At the toner inlet se ctio n, the toner agitator [G] has a spira l sh ape to move
the toner to the toner tank cavity.

2-37

30 November 1990

6.3 TONER DENSITY DETECTION

[ D ]

[ I ]

[ A ]

[ E ]

[ C ]

[ F ]

[ H ][ G ]

[ B ]

A: ID Sensor Pattern
B: ID Sensor
C: Original
D: Full Erase
E: ID Check
F: Edge Erase (copy cycle)
G: Insufficient Toner Condition
H: Sufficient Toner Condition
I: Sensor Pattern Image

The main CPU checks the image de nsity of the sensor pattern at th e
beginning of the first copy cycle (after the main switch is turne d on) and at
every tenth copy cycle.

After the sensor pattern [A] is developed, the image den sity sensor [B] (a
photosensor) checks its refle ctivit y. If the refle cted light is too strong, the CPU
determines that the toner densit y is too low. It th en add s toner to the
development unit.

Toner is not added all at once. The CPU ene rgize s t he ton er sup ply clutch to
add a selected amount of to ne r over th e ne xt 10 cycle s.

2-38

6.4 TONER DENSITY CONTROL

Low image density

High image density

30 November 1990

LED

ON

VSG

LED
ON

VSP

Image Density Sensor

CN102-A1

CN102-A8

CN102-B1

VR1

Main PCB

5V(VC)

CN101-A18

[ 24]

ANO

CPU

PA5

The image density senso r checks the density of the sensor patt ern image
once every 10 copy cycles. The CPU receives two voltage values directly
from the sensor: the value for the bare drum (Vsg) and th e valu e for the
sensor pattern imag e (Vsp ). These two values are then compa red to
determine whether or not more ton er sho uld be added.

1. Vsp ≤ 1/10 of Vsg ........ High image density (no toner added)

2. Vsp > 1/10 of Vsg ........ Low image density (toner is added)

(V)

VSG = 4.0 ± 0.2

VSG

VSP

+24V(VA)

MC

Toner Supply

Clutch

1/10 VSG = 0.4

0

Sensor

Bare

pattern

drum

1/10 VSG

(T)

0

When the image density is too low (Vsp ≥ 2.5 volt s), th e CPU chang es fro m
the detect mode to fixed tone r supp ly mode . It will be recove red wh en VSP
becomes less than 2.5 volts automat ically. If Vsg beco mes less th an 2.5
volts, the CPU determines that the sense d data is abnormal, then the CPU
changes from the dete ct mod e to fixed toner supply mode. However, toner
supply is re-established if Vsg become s greater than 2.5 volts. In eith er case
the service call indicator will blink.

SP mode #54 turns on the LED sen sor manually and adjust Vsg
automatically at 4±0.1V.

SP mode #55 displays Vsp and Vsg voltage values.

2-39

30 November 1990

6.5 TONER SUPPLY AMOUNT

This copier has two different ways of controlling the amount of toner supplied.
Normally, the detect supply mode system is used to control toner supply.
However, a fixed supply syste m ca n also be sele cted using SP #30.

SP #30 0 1
Toner supply mode Detect Fixed

Toner supply starts 43 pulses afte r the expo sure lamp turns off. Toner is
supplied at this time to prevent toner scattering on th e copies. The amount of
toner added depe nd s on th e size of copy paper being used.

Exposure
Lamp

ON

OFF

43pls

Toner Supply
Clutch

15%
30%

45%
60%

320msec

160msec

320msec

160msec

320msec

160msec

320msec

160msec

Paper
Size

Paper
Size

8 1/2 x 11,A4

>

< 8 1/2 x 11,A4

=

2-40

30 November 1990

Detect Supply Mode

If while the detect supply mode (SP#30 set to zero) an insufficient toner
condition is detected (Vsp > 1 /10 Vsg ), toner is supplied during each copy
cycle for the next ten copies.

The toner supply amou nt is set wit h SP #31 . The ton er supply at each Vsp
level is controlled in accorda nce with the following table.

SP #31 ( Display ) 0: 30%* 1: 15% 2: 45% 3: 60%
Vsp < 1/10 Vsg Sufficient Toner Condition
1/10 Vsg < Vsp < 1/8 Vsg 7% 3.5% 11.5% 15%
1/8 Vsg < Vsp < 1/5 Vsg 30% 15% 45% 60%
1/5 Vsg < Vsp < 1/4 Vsg 45% 30% 45% 60%
1/4 Vsg < Vsp < 1.5 V 60% 60% 60% 60%

1.5 V < Vsp < 2.5 V 100% 100% 100% 100%

*: Factory setting

Fixed Supply Mode

In the fixed supply mode (SP #30 set to 1), a fixed amount of ton er is add ed
every copy cycle as determined by setting of SP #32. There is no overtoning
detection mechanism.

SP #32 ( Display ) 0: 7%* 1: 4% 2: 11% 3: 14%

*: Factory setting

2-41

30 November 1990

6.6 TONER END DETECTION

Sufficient Toner Condition:

[C]

[B]

[D]

[E]

[A]

Toner End Condition:

[D]

Toner End Senso r

[D]

The toner end detection mecha nism actuates the toner end sensor [A] whe n
the toner tank is almost empty (60 to 100 grams remaining).

In the first figure, there is enough toner in the toner tank. The toner re sists the
movement of the to ne r agit ator [B] and the drive spring [C] stre tches. As a
result the flat surface of the ton er ag ita to r ca m [D] do es not align with the flat
section of the agitator gear [E], and the actuator is held in the toner end
sensor slit.

The second figure shows what happens if there is no t en ough toner in the
tank. In this case, the toner does not resist the movement of the agitator;
therefore, the ag itator gear spring forces the flat surface of the agitator drive
cam to align with the flat surfa ce of the toner agitator gea r. Whe n the flat
section comes to the act ua to r, a spring pulls the actuator out of the ton er en d
sensor and the sensor sends a toner en d sign al to the CPU. This starts the
toner end run, allowing 50 cop ies to be mad e be fore the Start key turns red.

2-42

30 November 1990

6.7 TONER OVERFLOW SENSOR CI RCUI T

GND

+5V

Tr.

CN101-A10

OSC

Freq.
Detection

Toner Overflow Sensor

Rectifier

The toner overflow sen sor sign als the CPU when the toner collect ion bot tle is
full.

[ 5]

Main PCB

A tiny tuning fork is used as th e sensing element for the to ne r overflow
sensor. This tuning fork is a damping element in a multivibrator circuit. As
long as there is nothing in contact with the tuning fork, the oscillating
frequency of the circuit stays LOW an d th e transistor stays off.

When toner presses against the tu nin g fo rk, the resist an ce of the
piezoelectric elemen ts th at are in contact with the tuning fork changes and
the oscillating frequency incre ase s. The frequency detection circuit passe s
the higher frequency signal to the rectifier which activates the switching
transistor. The transisto r se nds a LOW sign al to CN101-A10 on the main
board.

When the CPU receives this LOW signal, it signals the copier to stop, lights
the Used Toner Bottle indicator, and blinks the Service Call ind icator. Also, a
message instructing the custo mer to call for service is displayed on the
guidance display.

2-43

30 November 1990

7. IMAGE TRANSFER/PAPER SEPARATION

7.1 PRE-TRANSFER LAMP (PTL)

[A]

After the latent image is developed but before the ima ge is tra nsf erred to the
copy paper, the drum surface is illuminated by the pre -tra nsf er lamp [A]. This
illumination reduces the posit ive pote nt ial on the drum surf ace. This is to
prevent the toner particles transferred to the paper surface fro m b ein g
reattracted to the positively charged drum during the paper separat ion
process. It also makes image transfer and paper separation easier.

2-44

7.2 IMAGE TRANSFER

30 November 1990

[A]

[B]

The registration rollers [A] feed th e cop y paper th rou gh the tran sfe r ent rance
guide to the transfe r se ctio n. A high positive voltage is applied to th e transfer
corona wire [B], and the coron a wire generates positive ions. These positive
ions are applied to the reve rse side of the paper, and the pape r is
electrostatically attracted to the drum surface. This is due to the relationship
between the following three attractive fo rces:

A1: Paper and Toner
The attraction between the positively charged paper [C] and the
negatively charged toner.

A2: Paper and Drum (Aluminum core)
The attraction between the positively charged paper and the negative
countercharge on the aluminum core of the drum.

A3: Toner and Drum (Selenium layer)
The attraction between the positive ly charg ed drum and the negative ly
charged toner.

2-45

30 November 1990

Since the positive force ap plie d to the reverse side of the paper by th e
transfer corona is much gre ater than the strength of the posit ive ions on the
drum surface, A1 is greater than A3, and A2 is greate r t han A3.

A1 > A3
⇒ Transfer occurs

A2 > A3

[A2]

[A3]

[A1]

[C]

2-46

7.3 PAPER SEPARATION

30 November 1990

A1 > A2 > A3 ⇒ Separation occurs

After image transf er, the pap er is fed to th e separation section. This pro cess
separates the paper from the drum while holdin g the toner on the paper
surface.

Ac and dc currents are applied to th e separation corona wire, and the corona
wire generates ions. These posit ive ions are applied to the reverse side of the
paper, breaking the attractive forces A2 and A3; however, A1 is not broken.
The paper separates from the drum ta king the toner with it.

2-47

30 November 1990

7.4 TRANSFER/SEPARATION CO RONA P OWE R PACK

24V(VP)

Front Door

Main PCB

TC/SC

[ 5]

Trigger

SC Shift
Trigger

[ 5]

5V(Vc)

CN102-B17

CN102-A17

Front Door
Safety Switch

Safety Switch

CN2-1
CN2-3

CN2-7

CN2-8

CN2-2

TC/SC Power Pack

DC/DC
Converter

DC/AC
Inverter
and
DC/DC
Converter

T

5.78K(Vdc)

6.2K (Vac)

+465(Vdc)

S

The power pack has a dc-to-dc conve rte r and a dc-to-ac inverter.
The dc-to-dc converte r chan ges +24 volts (Vp) to 5.78 kilovolts dc for the

transfer corona. The inverter changes +24 volts (Vp) to 6.2 kilovolts ac with a
slight negative dc bias for the separation corona . Bo th coronas turn on when
the CPU applies a LOW at CN102-B17.

The main board sends a LOW trigg er sign al to the TC/SC power pack when
the lead edge of the paper turns on the regist rat ion sensor. The TC/SC power
pack turns off 328 millisecond s aft er the trailing edge of the copy pape r
deactuates the registration sensor.

Registration
Sensor

TC/SC
P.P.

328msec

2-48

30 November 1990

The separation corona curren t is n ot always con sta nt . It has two levels-- a
lead edge level and the normal level. The normal separation corona current
has an ac value of about 200 micro-amperes with little dc component.
However, at the leading edge, the dc value is reduced fro m abo ut –10
micro-amperes to a dc component of abo ut –30 micro-amp eres. This helps
the leading edge of the paper separate from the drum. This is accomplished
by the CPU supplying a LOW signal at CN102 -A1 7 to the TC/SC po wer pack.
(The above values for the dru m cu rren ts are the ore tical calculations for total
drum current.)

Normally, the lead edge separatio n corona current is applied to the first 10
millimeters of the copy paper. Howeve r, you can sele ct a marg in of 7 or 13
millimeters using SP mode #37.

SP #37

Ddc Timing

0: N

(10 mm)

1: Fast

(7 mm)

2: Late

(13 mm)

2-49

[E]

30 November 1990

7.5 PICK-OFF MECHANISM

[F]

[I]

[L]

[G]

[K]

[B]

[H]

[D]

[C]

[A]

Touch-and-Release Mechanism

The pick-off solenoid [A] energize s ju st af ter t he re gist rat ion rollers turn on.
The pick-off lever [B] rotat es cou nt erclockwise (rear view) and pushes the
pawl shaft pin [C]. The pawl sha ft [D] th en rota te s clockwise an d the pick-o ff
pawls [E] touch the drum. The pawl spring s [ F] hold th e pick-o ff pawls on the
shaft and prevent them from touching the drum too strongly. When the
leading edge of the pap er pa sses th e pick-off area and just before it rea ches
the fusing unit, the pick-off solenoid turns off. Th e pick-o ff shaft spring [G]
then rotates the pick-off lever to move th e pick-o ff pawls away from the drum.

[J]

Side-to-Side Movement

The pick-off pawls do not always contact th e dru m in the same pla ce bu t
instead move slightly to the sid e on each copy cycle.
The pick-off pawl shaft [H] and the cam ride r [ I] are join ed by a one-way
bearing [J]. Each time th e pick-off pawl solenoid turns on, th e on e-way
bearing causes the cam rider to turn together with the pick-off pawl shaft. As
the cam rider turns, it and the pawl shaft are forced to move laterally by a
cam [K]. When the pawl shaft rotates the pawls away fro m the drum,
however, the cam rider does not tu rn.
Pawl lateral movement is 0. 1 to 0.2 millimete r per copy cycle. After moving
about 8 millimeters, the cam ride r p asse s the lobe of th e cam an d the pawl
shaft is returned to its start position by the pawl shaft spring [G].

2-50

7.6 PICK-OFF TIMING

Registration Start Signal

Resistration
Clutch

Pick-off
Solenoid

30 November 1990

612 msec

When the registration rollers start rotating, the CPU simultaneously supplies
a LOW signal at CN101-A11. This L OW sign al en erg izes th e pick-off
solenoid.

The CPU waits 612 milliseconds until the lea d edge of th e paper re ach es th e
pick-off area before turning of f th e pick-o ff solen oid.

24V

Main PCB

CN101-A11

Pick-off SOL [ 24]

Pick-off
SOL

2-51

30 November 1990

7.7 PRE-TRANSFER LAMP AND QUENCHING LAMP
CIRCUIT

Main PCB

PTL/QL
Trigger [ 5]

CN101-A2

CN2-6

TC/SC P.P.

CN1-7

24V(Vp)

CN2-1

CN2-2
CN1-10

CN1-2

P-GND

CN1-1

CN1-3

Front Door Safety Switch

Stabilizer

24V(Vp)

5V

DC/AC
Inverter

P-GND

CN1-4

430V(Vac)

QL

430V(Vac)

PTL

When the main motor is energized, the main board outputs a LOW signal at
CN101-A2 to energize the sta bilize r p owe r pack. This LOW signal is routed
through the TC/SC power pack to the stabilizer.

The stabilizer has a dc-to-ac inverter which change s +24 volt s (Vp) to high
voltage ac (approximately 430 volts ac).

2-52

8. DRUM CLEANING

8.1 OPERATION

[C]

30 November 1990

[E]

[F]

[G]

[A]

Drum cleaning is accomplished by the pre-cleaning coron a (PCC) [A],
cleaning brush [B], an d clea ning blade [C].

As the surface of the drum enters the clean ing unit , th e PCC applies an ac
charge. This loosens the toner on the drum.

In earlier models, the cleaning blad e remo ved most of the toner, but in this
model the cleaning brush remove s the bulk of the ton er (ab ou t 90%). This is
because the brush uses electric potential as well as mechanical action to
remove the toner. The cleaning brush has a positive charge that attracts the
negative toner.

[B]

[D]

After picking up the toner, the cleaning brush turns inside the cleaning unit.
Just inside the unit, it brush es ag ain st a be ater bar [D]. The beater bar
dislodges paper dust but is not effective in removing the negatively charge d
toner.

Next the cleaning brush brushes against the bias roller [E]. The bias rolle r,
which has a charge of +300 volts, attracts the toner from the cleaning brush.
The bias roller blade [F] scrapes the toner from the bia s roller and the toner
drops on the toner collection coil [G]. The cleaning blad e removes the
remaining toner (about 10 %). The to ner co llect ion coil t ran spo rts th e use d
toner to the rear of the machine where it falls into the used tone r bo tt le.

2-53

30 November 1990

8.2 PRE-CLEANING CORONA AND BIAS ROLLER

[C]

[B]

[A]

The pre-cleaning coro na [A] app lies an ac volta ge to th e drum and any toner
remaining on the drum’s surface. This is to reduce th e positive charg e of the
drum surface. A negative bias is used beca use ton er more re adily a ccep ts a
negative charge, and a negative charg e is more sta ble than a positive charge.

The cleaning brush [B ] is cond uctive and contacts both the drum and the bias
roller [C] within the cleaning unit. The bias rolle r has a positive dc volta ge
(300 volts) applied to it. This enables the cleaning brush to remove toner from
the drum efficiently and deposit it in the cleaning unit.

2-54

8.3 DRIVE MECHANISM

[D]

[F]

30 November 1990

[A]

[C]

[E]

[G]

[B]

The cleaning unit is driven by the main motor. Mechanical drive is transmitt ed
to each part as follows:

Main Motor [A] ⇒ Registration Roller Drive Belt [B] ⇒ Gears [C] ⇒
Cleaning Brush [D] ⇒ Toner Collection Coil [E] ⇒ Bias Roller Gear [F]

A groove cam [G] inside th e to ne r collection coil gear moves the cleaning
blade from side to side as lon g as mech an ical drive is applie d. This lo ose ns
toner build-up between the clean ing blad e and th e dru m.

2-55

30 November 1990

8.4 CLEANING BLADE

[F]

[I]

[D]

[C]

[G]

[E]

[B]

[A]

[H]

The cleaning pressure mechanism is shown above. When the cleaning
solenoid [A] is energized , it tu rns the cleaning solenoid lever [B] clockwise
(rear view). Due to the pull of the cleaning blad e pressure spring [C], the
pressure arm [D] also turns clockwise and push es th e cleaning blade lever
[E] up. The cleaning blade holder then rotate s a nd the cle an ing blad e [F]
presses against the drum. Blade pre ssure is limited by the pressure spring [I].

The cleaning blade is mou nt ed on th e bla de bracke t with a single swivel
screw [G] at its exact center. With this typ e of mo unting, the blade sets
parallel and applies even pressure automat ically. Also since pressu re is
transmitted to the cen ter, a single pressure spring is used.

The blade scraper [H] is moun te d in contact with the bottom side of the
cleaning blade. Wh en pressure is applied to the cleaning blade, it is forced
forward and bends at its outer edge. When pressure is relea sed from the
blade, it snaps back to its original position. Simultaneously, the mylar of the
blade scraper scrapes of f th e excess toner and paper dust from th e ed ge of
the blade. This helps to mainta in ef ficie nt clean ing . The blade pressure is
released when there is n o key inp ut for 1 minute, 10 seconds afte r a pap er
misfeed occurs, or when the safety switches open.

2-56

8.5 CLEANING SOLENOID CI RCUI T

30 November 1990

Main PCB

Cleaning
Solenoid[ 24]

CN101-B7

SOL

24V(Va)

When the Start key is pressed, the CPU o utpu ts a low sign al at CN101-B7 to
energize the cleaning solen oid . The ma in mot or tu rns on 200 millisecon ds
later. The CPU turns off the cleaning solenoid 1 minute after the main motor
is turned off to clean the edge of the cleaning blade.

10 sec (1)

Main Motor

12 pls (3)

5 sec

Cleaning

Solenoid

(2)

The CPU keeps track of the total numb er of copie s. Eve ry 1 00 copies it does
the following:
(1) 10 seconds after copying finishes and the main moto r comes to a
complete stop, the CPU instruct s the main mot or to brief ly turn on again and
rotate in the reverse direct ion . (This a lso occu rs 10 seco nd s aft er th e front
door is opened or 10 seconds after a paper misfee d occu rs.)
(2) Five Seconds after the main motor shuts off again, the cleaning solenoid
de-energizes, energizes, and de-energizes again to clean the edge of the
cleaning blade twice.
(3) Finally, the main motor turns on again an d rot at es fo rward for 12 pulses.
Toner that has accumulat ed on th e dru m su rfa ce directly behind the cleanin g
blade is thus moved past the clean ing blade. The CPU counter is then rese t
to 0.

NOTE: The actual number of copies made between cleaning cycle may

exceed 100 if continuo us cop ying is in progress. The above
sequence also occurs 10 secon ds af ter the front door is opened or
10 seconds after a paper misfeed occu rs.

2-57

30 November 1990

8.6 PRE-CLEANING CORONA CIRCUIT

24V (Vp) P-GND

Front Door Safety Switch

Main PCB

PCC [ 5]

5V (Vc)

CN101B3

CN2-4

TC/SC P.P.

CN1-8
CN1-9

( 24)

CN1-4

PCC P.P.

CN1-2
CN1-1

DC/DC
Inverter

CN1-3

4.25KVac

-450Vdc

The PCC power pack receives 24 volts (Vp) from the TC/SC power pack. To
energize the PCC power pack, the main bo ard supp lies a LO W sig nal a t
CN101-B3 to the PCC power pack thro ugh the TC/SC power pack, which in
turn applies a LOW signal at CN1-4 to energize the PCC power pack.

The PCC power pack energizes at the same time th at the main motor turns
on and de-energizes 570 milliseconds after the registra tio n sen sor turns of f.

PCC

Main Motor

Registration
Sensor

PCC P.P.

570msec

2-58

8.7 CLEANING HEATER

Cleaning
Heater

30 November 1990

AC Power

Transformer

100VAC

Thermo

Switch

Drum Heater

Anticondensation

Heater

Cleaning Heater

RA2

Main Switch

The rapid temperat ure change (from cold to the opera tin g temperature) may
cause the crack of the clea nin g blade edge. To prevent this, the clean ing
heater (18W) is installed to keep the temperat ure of the drum area always
above 25°C. It is turned on while the main swit ch is turn ed off . The
thermoswitch located at the rear side of the cleaning casing cut the 100 V ac
power when the temperature reaches 50°C to prevent the toner from being
melted.

2-59

30 November 1990

9. QUENCHING

9.1 OPERATION

[B]

[A]

The pre-quenching coro na (PQC) [A ] ap plie s a posit ive dc corona (5 kilovolts)
to neutralize the negative charge re main ing on the dru m’s su rfa ce fro m the
pre-cleaning corona. Simult an eously, the quenching lamp [B] neutralizes any
remaining positive cha rge on th e drum. Both a lamp and a dc corona are
required because the quench ing lamp is less effective against negative
charges than positive charges.

The quenching lamp also stabilize s the drum sen sitivit y f rom th e first cycle by
pre-illuminating the drum.

This machine uses a cold catho de tub e as th e qu en chin g lamp. The cold
cathode tube (ac 430 volts, 1.3 watt s) consumes less power, releases less
heat, and is brighter. Also, its effective light is in the most sensitive range of
the drum. A plastic filter prevents toner from being deposited on the lamp.

2-60

9.2 PRE-QUENCHING CORONA CI RCUI T

5VDC

5K(VDC)

+24V

30 November 1990

Main PCB

PQC/QL[ 5]

CN2-3

CN101-A2

T/S P.P.

CN1-6

CN2-6

GND (p)

PQC/Cleaning Bias P.P.

CN1-1

CN1-3

CN1-2

DC/DC

Circuit operation begins with the applicatio n of +24 volt s to CN1-1 on the
PQC power pack. This is the power source for th e hig h-vo ltage (dc 5
kilovolts) corona.

PQC

When the Start key is pressed, the CPU energizes the PQC power pa ck
through the TC/SC power pack by supplying a LOW at CN101-A2. This turns
on the LED, and the phot otransistor energizes the pre-q ue nch ing corona
(PQC). The PQC turns off when the main motor is turned off.

2-61

30 November 1990

10. PAPER FEED

10.1 OVERVIEW

[G]

[F]

[E] [D]

[C]

[H]

[B]

This copier has three paper feed stat ion s. The large capacity tray (3,000
sheets) is installed at the first stat ion [A], and two cassettes (500 sheets
each) can be set at the second and third statio ns [B]. When the manual feed
table is used [C], paper is feed throu gh the first fe ed stat ion .

All paper feed stations use the FRR system: a pick-up roller [D] , a paper feed
roller [E] and a reverse roller [F]. Rotation of the pick-up roller drives the top
sheet of paper to the fee d and reverse rollers. Then, the feed and reve rse
rollers take over the paper drive. If more th an one shee t is fed by the pick-up
roller, the reverse roller rotat es in th e op posite direction and prevents all but
the top sheet from passing throu gh to the reg istra tion/relay rollers [G,H].

[A]

2-62

10.2 PAPER LIFT MECHANISM

[C]

[B]

30 November 1990

[E]

[A]

[D]

(1st Paper Feed Station - LCT)
The bottom plate of the LCT is raised and lowered by the tra y motor

(reversible ac motor) [A] and the drive chain s [B] . When the main switch is on
and the tray cover is closed, the tray motor rot ates clockwise and raises the
bottom plate until the top sheet push es up the pick-up roller [C]. (The lift
sensor is deactuated and the CPU turns off the tray motor.)

If the tray down switch [D] is pre ssed or all p ap er run s o ut , th e tray motor
rotates counterclockwise to lowe r the botto m plate. However, it is not be
lowered all the way down at this time. When the tray paper positio n sen sor
[E] turns on, the tray motor sto ps on ce. At this p oin t, the botto m plate (or the
top sheet of the paper) is positioned about 5cm below from th e top. This
gives enough space for th e cust omer to replenish about 500 she ets of paper.
If the tray down switch is the n pre ssed again, the bottom plat e move s down
and stops once again when the top sheet of the paper just passes the paper
position sensor. In this way, the botto m plate is lowered 5cm at each press of
the tray down switch. This allows the users to re ple nish pap er in con ven ient
amounts and at the same posit ion.

2-63

[E]

[F]

30 November 1990

[B]

[C]

[A]

[D]

[F]

[B]

[C]

[D]

(2nd and 3rd Paper Feed Stations - Cassettes)
When the cassette is inserted into the copier, the cassette actuator pin [A] is

pushed down by the casset te . The lift motor unit then mecha nica lly p ivot s
clockwise at point [B] so that the lif t gear [C] engages with the sector gear [D].

Simultaneously, the paper size act uato r plate actuates the paper size sensor.
The CPU then detects tha t a casse tte has been inserted and turns on the lift
motor. The lift motor raises t he bot to m plat e until th e to p sheet push es up the
pick-up roller.

When the paper pushes up the pick-up roller [E], the lift senso r [F] is
de-actuated and the CPU turns off the lift motor.

2-64

10.3 PAPER VOLUME DETECTION

30 November 1990

[A]

[B]

1
2
3
4
5

Paper
Volume

(Approx.)

Indicator

3000
2400

2400
1800

1800
1200

1200

600

600

1

(1st Paper Feed Station - LCT)
Five paper volume sensors are locat ed vertica lly at th e rear side of the LCT

[A]. An actuat or [B ] on the bottom plate sha ft activates a sensor
corresponding to the position of the bottom plate. Paper feed PCB info rms
the CPU of the paper volume base d on wh ich of sensors turns on.

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30 November 1990

[A]

[B]

[A]

5
4
3

2
1

1
2
3
4
5

[C]

Paper
Volume

(Approx.)

Indicator

500
400

400
300

300
200

200
100

100

1

0

(2nd and 3rd Paper Feed Stations - Cassettes)
Paper volume is monitored by five photo int erru ptors [A]. These sensors

detect, in five increments of ap pro ximately 100 sheets each, how much paper
is in the cassette. As pape r lea ves from the cassette, the bo tt om plate [B]
must rise to maintain the level of the top shee t. The more the botto m plate
rises, the greater number of photointe rrup to rs are de-act ivat ed by the paper
volume actuator at the rear end of the bottom plate shaft. As each
photointerruptor is de-activated, the CPU turns off its corresponding Paper
Volume indicator [C].

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10.4 PAPER FEED DRIVE

[F]

[A]

30 November 1990

[B]

[C]

[D]

[E]

[G]

(1st Paper Feed Station - LCT)
The pick-up rollers [A] and the feed rollers [B] are driven by the paper feed

motor [C], which is controlled by the paper feed motor PCB.
The main board sends a pape r fee d sign al to the paper feed control board,

which then energizes the paper feed clutch [D]. The clut ch gear’s rotation is
transferred to the feed roller sha ft.

The pick-up roller rotates in the same direction as the feed roller. This is
accomplished throu gh the id le gear [E].

The paper feed motor drives the separation rollers [F] via the paper feed
drive chain [G] and the appropria te gears.

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30 November 1990

[A]

[B]

[D]

[C]

[E]

(2nd and 3rd Feed Stations - Cassettes)
The pick-up rollers [A] and the feed rolle rs [ B] are drive n by th e casse tte bank

motor [C].
The main board sends a pape r fee d sign al to the cassette bank board, which

then energizes the paper feed clutch [D]. The clu tch gear’s rota tio n is
transferred to the feed roller sha ft.

The pick-up roller rotates in the same direction as the feed roller. This is
accomplished throu gh the id le gear [E].

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10.5 MANUAL FEED

30 November 1990

[A]

[B]

[C]

In manual feed mode, up to 50 she ets (normal weight) can be loaded on the
manual feed table and fed into the copier without a cassette. Manual feed
mode uses the rollers of the first feed station.

When the manual feed table is opened, the manual feed sensor [A] sends a
low signal to the CPU. The CPU then shifts to manual feed mode. The
actuator [B] of the first cassette paper end sensor stays in the same position,
but the CPU detects a paper end condition in the manual feed table and
lights the Add Paper indicator.

When paper is inserted into the manual feed table, the manual feed paper
end sensor is actuated. The CPU then turn s off the Add Paper indicator.

In manual feed mode, the manual fe ed solen oid [C] lifts the pick-up roller.
This solenoid has a longer stroke because the pick-up roller must be lifted
higher when the man ual feed table is used.

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[A]

30 November 1990

Pick-up Roller Up/Down Movement

[B]

[A]: 1st Pick-up Solenoid
[B]: Manual Feed Solenoid

Pick-up Roller Up/Down Movement
When the leading edge of the paper passes between the feed roller and

separation roller, the CPU energizes the solenoid. The pick- up roller is then
lifted to its upper position which is out of paper path.

This copier has three pick-up rollers an d use s four so len oid s. Three of them
are used for each paper feed station. The other solenoid is for the manual
feed.

After the trailing edge of the paper passes under the pick-up roller, the
pick-up roller drops onto the paper sta ck in prep aration for the next copy
cycle.

The same mechanism is used for 2n d an d 3rd paper feed stations.

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