Ricoh FT 3013 Service Manual

IMPORTANT SAFETY NOTICES

PREVENTION OF PHYSICAL INJURY

1.Before disassembling or assembling parts of the copier and peripherals, make sure that the copier power cord is unplugged.

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

3.Note that the optional anti-condensation heaters are supplied with electrical voltage even if the main switch is turned off.

4.If any adjustment or operation check has to be made with exterior covers off or open while the main switch is turned on, keep hands away from electrified or mechanically driven components.

5.The inside and the metal parts of the fusing unit become extremely hot while the copier is operating. Be careful to avoid touching those components with your bare hands.

6.When the development unit, cleaning unit, drum unit, or the DF is removed from the machine, the upper unit becomes lighter. If the upper unit is released under this condition, it tends to open very abruptly. The service engineer might be injured if he is leaning over the machine at this time. Also, the machine might move due to the shock of the upper unit opening abruptly. To avoid possible injury or machine damage, hold the upper unit firmly when opening the unloaded upper unit.

7.Due to variation in the tolerance of the torsion springs, the upper unit cannot be held at an angle of 16 degrees by itself when the DF is installed. To avoid possible injury, always use the upper unit stand to keep the upper unit open.

HEALTH SAFETY CONDITIONS

1.Never operate the copier without the ozone filter installed.

2.Always replace the ozone filter at 80K copy intervals.

3.Toner and developer are non-toxic, but if you get either of them in your eyes by accident, it may cause temporary eye discomfort. Try to remove with eye drops or flush with water as first aid. If unsuccessful, get medical attention.

©1994 By Ricoh Company Ltd. All rights reserved

OBSERVANCE OF ELECTRICAL SAFETY STANDARDS

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

–CAUTION –

2.The RAM pack has a lithium battery which can explode if handled incorrectly. Replace only with same RAM pack. Do not recharge, or burn this battery. Used RAM pack must be handled in accordance with local regulations.

SAFETY AND ECOLOGICAL NOTES FOR DISPOSAL

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

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

3.Dispose of replaced parts in accordance with local regulations.

4.When keeping used lithium batteries (main control boards) in order to dispose of them later, do not store more than 100 batteries (main control boards) per sealed box. Storing larger numbers or not sealing them apart may lead to chemical reactions and heat build-up.

SECTION 1

OVERALL MACHINE

INFORMATION

24 June 1994 SPECIFICATIONS

1. SPECIFICATIONS

Configuration:	Desk top
Copy Process:	Dry electrostatic transfer system
Original Type:	Sheet/Book
Original Alignment:	Left center
Original Size:	Maximum:	A3/11" x 17" (lengthwise) – A152
		copier
		B4/10" x 14" (lengthwise) – A151
		copier
Copy Paper Size:	Maximum:	B4/10" x 14" (lengthwise)

		Minimum:
		Paper Tray: A5/51/2" x 81/2" (lengthwise)
		Bypass Feed: A6/51/2" x 81/2" (lengthwise)
Copy Paper Weight:		Paper tray feed – 64 to 90 g/m2 (17 to 24 lb)
		Bypass feed – 52 to 105 g/m2 (14 to 28 lb)
Reproduction Ratios:		2 Enlargement and 3 Reduction (A152 copier only)
			A4 Version		Letter Version
		Enlargement	141%		129%
			122%		121%
		Full size	100%		100%
			93%		93%
		Reduction	82%		74%
			71%		65%
Zoom:		From 61% to 141% in 1% steps
		(A152 copier only)
Copying Speed:		13 copies/minute (A4/81/2" x 11" lengthwise)
		10 copies/minute (B4/81/2" x 14")
Warm-Up Time:		30 seconds (at 20°C/68°F)
First Copy Time:		9 seconds (A4/81/2" x 11" lengthwise)
Copy Number Input:		Number keys, 1 to 99
Manual Image Density		7 steps
Selection:

1-1

SPECIFICATIONS	24 June 1994
Automatic Reset:	1 minute standard setting; can also be set to 3
	minutes or no automatic reset.
Energy Saver Function:	Automatic
Paper Capacity:	Paper tray – 250 sheets
	Bypass feed table – 1 sheet
Toner Replenishment:	Cartridge exchange (320 g/cartridge)
Copy Tray Capacity:	100 sheets (B4/10" x 14" or smaller)
Power Source:	110V/ 60Hz/ 15A (for Taiwan)
	115V/ 60Hz/ 15A (for North America)
	220V – 240V/ 50Hz/ 8A (for Europe)
	220V/ 60Hz/ 8A (for Middle East)
	220V/ 50Hz/ 8A (for Asia)
	(Refer to the serial number plate (rating plate) to

determine the power source required by the machine.)

Power Consumption:

Noise Emission:

	Copier Only	With DF
Maximum	1.4 kVA	1.5 kVA
Warm-up	620 VA (average)	640 VA (average)
Copy cycle	810 VA (average)	860 VA (average)
Ready	160 VA (average)	180 VA (average)
	Copier Only	With DF
Maximum	58 db	60 db
Copy cycle	Less than 55 db	Less than 55 db
Ready	Less than 39 db	Less than 39 db

Dimensions:

		Width	Depth	Height
	Copier with platen cover and	713 mm (28.1")	592 mm (23.3")	400 mm (15.7")
	copy tray
	Copier with document feeder	713 mm (28.1")	592 mm (23.3")	463 mm (18.2")
	and copy tray

1-2

24 June 1994		SPECIFICATIONS
Weight:	Copier only:	43 kg (94.8 lb)
	With DF:	50 kg (110.2 lb)
Optional Equipment:	Document feeder (A152 copier only)
(Sales items)	Key counter
Optional Equipment:	Drum anti-condensation heater
(Service items)	Optics anti-condensation heater
	Pre-transfer lamp
	Optics cooling fan (for A151 copier only)

∙ Specifications are subject to change without notice.

1-3

COPY PROCESSES AROUND THE DRUM

24 June 1994

2.COPY PROCESSES AROUND THE DRUM

2.EXPOSURE

1.DRUM CHARGE

3. ERASE

8. QUENCHING

4. DEVELOPMENT

7. CLEANING

	6. PAPER	5. IMAGE TRANSFER
	SEPARATION

1-4

24 June 1994

COPY PROCESSES AROUND THE DRUM

1. DRUM CHARGE

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

2. EXPOSURE

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

3. ERASE

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

4. DEVELOPMENT

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

5. IMAGE TRANSFER

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

6. PAPER SEPARATION

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

7. CLEANING

The cleaning blade removes any toner remaining on the drum.

8. QUENCHING

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

1-5

COPY PROCESS CONTROL 24 June 1994

3. COPY PROCESS CONTROL

	Grid Voltage	Exposure Lamp	Development Bias	Erase Lamp
		Voltage	Voltage
Image	Standard image			Depends on
		Base exposure lamp	Base bias voltage factor
Density	density grid voltage	voltage (Manual or ADS	(Manual or ADS mode	paper size
Control	(–680 V)	mode) (SP48)	[SP34])	and
				reproduction
	+	+	+
				ratio
	Drum residual voltage	VL correction factor
			Image bias voltage
	(Vr) correction factor	+	adjustment factor
	(SP67)	Reproduction ratio	(SP37)
	+	correction factor (A152
		copier only)
			+
	Auto image density
	level factor (SP34)		Drum residual voltage
			(Vr) correction factor
			Note:
			Base bias voltage at
			manual ID level 7 can be
			adjusted by SP50
Toner	Standard ID sensor	Same as image density		ID sensor
			Depends on ID sensor
Density	grid voltage	control	bias setting (SP33)	pattern erase
Detection	(–460 V)			(Vsg
	+			detection:
	Drum wear correction		Note:	Full erase)
	factor (SP57)		For initial 499 copies
			bias voltage is increased
			by –20 volts
Residual	Standard ID sensor	Same as image density	0 Volts (Fixed)	Full erase
Voltage	grid voltage	control		(All LEDs ON)
(Vr)	(–460 V)
Detection	+
	Drum wear correction
	factor (SP57)
Between	0 Volts (Fixed)	Exposure lamp turns off	–160 Volts (Fixed)	Full erase
Copies			+	(All LEDs ON)
			Image bias voltage
			adjustment factor
			(SP37)
			+
			Drum residual voltage
			(Vr) correction factor

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

1-6

24 June 1994

MECHANICAL COMPONENT LAYOUT

4. MECHANICAL COMPONENT LAYOUT

	16	17	18	19		20	21	22 23 24		25	26
											27
	15										28
	14
	13
											29
	12										30
11											31
	10										32
											33
	9
	8	7	6		5	4		3	2		1
1.	Semicircular Feed Rollers			12.	Hot Roller Strippers				24.	Erase Lamp
2.	Paper Tray			13.	Exhaust Blower Motor				25.	Drum
3.	Registration Rollers			14.	3rd Mirror				26.	4th Mirror
4.	Transfer and Separation			15.	2nd Mirror				27.	5th Mirror
	Corona Unit			16.	1st Mirror				28.	Optics Cooling Fan Motor
5.	Pick-off Pawl			17.	Ozone Filter					(A152 Copier only)
6.	Cleaning Unit			18.	Used Toner Tank				29.	Toner Supply Unit
7.	Pressure Roller			19.	Cleaning Blade				30.	Development Unit
8.	Fusing Unit			20.	Quenching Lamp				31.	2nd Relay Rollers
9.	Hot Roller			21.	Charge Corona Unit				32.	By-pass Feed Table
10.	Exit Rollers			22.	Lens				33.	1st Relay Rollers
11.	Copy Tray			23.	6th Mirror

1-7

ELECTRICAL COMPONENT LAYOUT 24 June 1994

5. ELECTRICAL COMPONENT LAYOUT

		23	24
	22		25
	21		26
	20		27
	19		28
			29
	18

30

31

17

16

15

32

14

13						33
						34
12
11
10
9	8	7			36	35
		6	5	38	37
			4 3	1
				2

1.Paper Tray Switch

2.Relay Sensor

3.Registration Clutch

4.Optics Cooling Fan Motor (A152 only)

5.Registration Sensor

6.Image Density Sensor

7.Power Pack-TC/SC

8.Operation Panel Board

9.Erase Lamp

10.Total Counter

11.Quenching Lamp

12.Fusing Lamp

13.Front Cover Safety Switch

14.Main Switch

15.Fusing Thermoswitch

16.Exit Sensor

17.Exhaust Blower Motor

18.Optics Thermofuse

19.Auto Image Density Sensor

20.Fusing Thermistor

21.Exposure Lamp

22.Lens Motor (A152 copier only)

23.Scanner Home Position Sensor

24.Optics Thermistor

25.Lens Home Position Sensor

(A152 copier only)

26.Power Pack-CC/Grid/Bias

27.AC Drive Board

28.Fusing Triac (115 V only)

29.Scanner Motor

30.4th/5th Mirror Home Position Sensor (A152 copier only)

31.4th/5th Mirror Motor (A152 copier only)

32.Main Motor Capacitor

33.Main Board

34.Main Motor

35.Toner Supply Clutch

36.DC Power Supply Board

37.Relay Roller Clutch

38.Paper Feed Clutch

1-8

24 June 1994 ELECTRICAL COMPONENT DESCRIPTIONS

6. ELECTRICAL COMPONENT DESCRIPTIONS

Motors

	SYMBOL	NAME	FUNCTION	INDEX
				NO.
			Drives all the main unit components except for the
	M1	Main Motor	optics unit and fans. (115/220–240 Vac [ac	34
			synchronous])
	M2	Scanner Motor	Drives the scanners (1st and 2nd). (dc stepper)	29
			Positions the lens according to the selected
	M3	Lens Motor	magnification. (dc stepper)	22
			¼ A152 copier only
		4th/5th Mirror	Positions the 4th/5th mirrors according to the
	M4		selected magnification. (dc stepper)	31
		Motor
			¼ A152 copier only
		Optics Cooling	Prevents built up of hot air in the optics cavity.
	M5		(24 Vdc)	4
		Fan Motor
			¼ A152 copier only
		Exhaust Blower	Removes heat from around the fusing unit and
	M6		moves the ozone built up around the charge	17
		Motor
			section to the ozone filter. (24 Vdc)

Magnetic Clutch

	SYMBOL	NAME	FUNCTION	INDEX
				NO.
	MC1	Registration	Drives the registration rollers.	3
		Clutch

Magnetic Spring Clutches

	SYMBOL	NAME	FUNCTION	INDEX
				NO.
	MSC1	Toner Supply	Drives the toner supply roller.	35
		Clutch
	MSC2	Relay Roller	Drives the 1st and 2nd relay rollers.	37
		Clutch
	MSC3	Paper Feed	Starts paper feed.	38
		Clutch

1-9

ELECTRICAL COMPONENT DESCRIPTIONS 24 June 1994

Switches

	SYMBOL	NAME	FUNCTION	INDEX
				NO.
	SW1	Main Switch	Supplies power to the copier.	14
	SW2	Front Cover	Cuts the ac power line, when the front cover is	13
		Safety Switch	open.
	SW3	Paper Tray	Detects when the paper tray is set.	1
		Switch

Sensors

	SYMBOL	NAME	FUNCTION	INDEX
				NO.
	S1	Scanner Home	Informs the CPU when the 1st scanner is at the	23
		Position Sensor	home position.
		Lens Home	Informs the CPU when the lens is at the home
	S2		position (full size position).	25
		Position Sensor
			¼ A152 copier only
		4th/5th Mirror	Informs the CPU when 4th/5th mirrors assembly is
	S3	Home Position	at the home position (full size position).	30
		Sensor	¼ A152 copier only
	S4	Registration	1) Detects misfeeds.	5
		Sensor	2) Controls the relay roller clutch stop timing.
	S5	Exit Sensor	Detects misfeeds.	16
			1) Detects when copy paper is set on the
	S6	Relay Sensor	by-pass feed table.	2
			2) Detects misfeeds.
	S7	Image Density	Detects the density of the image on the drum to	6
		(ID) Sensor	control the toner density.
		Auto Image
	S8	Density Sensor	Senses the background density of the original.	19
		(ADS)

Printed Circuit Boards

	SYMBOL	NAME	FUNCTION	INDEX
				NO.
	PCB1	Main Board	Controls all copier functions both directly and	33
			through the other PCBs.
	PCB2	AC Drive Board	Drives the main motor, exposure lamp, fusing	27
			lamp, and quenching lamp.
	PCB3	DC Power	Converts the wall outlet ac power input to +5 volts,	36
		Supply Board	+24 volts, and a zero cross signal.
		Operation Panel	Informs the CPU of the selected modes and
	PCB4		displays the copier status and condition on the	8
		Board	panel.

1-10

24 June 1994 ELECTRICAL COMPONENT DESCRIPTIONS

Lamps

	SYMBOL	NAME	FUNCTION	INDEX
				NO.
	L1	Exposure Lamp	Applies high intensity light to the original for	21
			exposure.
	L2	Fusing Lamp	Provides heat to the hot roller.	12
	L3	Quenching Lamp	Neutralizes any charge remaining on the drum	11
			surface after cleaning.
			Discharge the drum outside of the image area.
	L4	Erase Lamp	Provides leading/trailing edge erase and side	9
			erase.

Power Packs

	SYMBOL	NAME	FUNCTION	INDEX
				NO.
	P1	Power Pack	Provides high voltage for the charge corona, grid,	26
		–CC/Grid/Bias	and development roller.
	P2	Power Pack	Provides high voltage for the transfer and	7
		–TC/SC	separation corona.

Counter

	SYMBOL	NAME	FUNCTION	INDEX
				NO.
	CO1	Total Counter	Keeps track of the total number of copies made.	10

Others

	SYMBOL	NAME	FUNCTION	INDEX
				NO.
	TH1	Fusing	Monitors the fusing temperature.	20
		Thermistor
	TH2	Optics	Monitors the optics temperature.	24
		Thermistor
	TS	Fusing	Provides back-up overheat protection in the fusing	15
		Thermoswitch	unit.
	TF	Optics	Provides back-up overheat protection around the	18
		Thermofuse	exposure lamp.
	C	Main Motor	Start capacitor.	32
		Capacitor
			Switches the fusing lamp on and off. (115 V only)
	TR	Fusing Triac	Note: In the 220V-230V/240V version, the triac	28
			is built-in the ac drive board

1-11

DRIVE LAYOUT 24 June 1994

7. DRIVE LAYOUT

G13	BP6	BP5	G10
G14	G12 TB3	G11	G23
			G9
			G8
G15			G7
G16
G17			G6

G5

G18

G19

TB1

G4

G3

G20 G21 G22

BP2

BP1G1

G2

BP4

BP3

G24

G26

G9

G25

G8

TB2

G2

G1: Main Motor Gear

G1

G2: Relay Gear

G23: Timing Belt Drive

G10 Relay gear

G8: Relay Gear

Gear

G11: Timing Belt Drive Gear

G9: Relay Gear

BP1: Timing Belt Pulley

B

BP5: Timing Belt Pulley

TB1: Timing Belt

Cleaning Unit

TB3: Timing Belt

G3: Fusing Drive Gear

A

Development Section

Fusing and Exit Unit

BP6: Timing Belt Pulley

G4: Hot Roller Gear

G12: Development Gear

G7: Relay Gear

Development Unit

G6: Relay Gear

G13: Relay Gear

G5: Exit Roller Gear

G14: Toner Supply CL Gear

Toner Supply CL			Toner Supply Unit

1-12

24 June 1994

G15: Registration CL

Gear

Registration CL

Registration Rollers

G20: Relay Gear

G17: Relay Roller CL

Gear

Relay Roller CL

G16: 2nd Relay Roller

Gear

2nd Relay Rollers

G18: Relay Gear

G19: 1st Relay Roller

Gear

1st Relay Rollers

A

Paper Feed Section

BP2: Timing Belt Pulley

G22: Relay Gear

Paper Feed Section

G21: Paper Feed CL

Gear

Paper Feed CL

Feed Rollers

DRIVE LAYOUT

B

G24: Timing Belt Drive

Gear

BP3: Timing Belt Pulley

TB2: Timing Belt

BP4: Timing Belt Pulley

G25: Relay Gear

G26: Drum Drive Gear

1-13

POWER DISTRIBUTION

24 June 1994

8. POWER DISTRIBUTION

AC Power (115V or 220V – 240V)

Anti-condensation Heaters Main SW -Drum (Option)

-Optics (Option)

Cover Safety SW

Scan

5V

Operation Panel Board

Signal

Sensors

Power Relay

24V (VA)

5V (VC) Switches

(RA401)

DF Interface Board

(A152 copier only)

Fusing Lamp	24V (VA)			Thermistors
Drive Circuit
Fusing Lamp		RAM
Exposure Lamp	24V (VA)	Pack		Solenoids
Drive Circuit				Clutches
				Power Packs
Exposure Lamp
				Lens Motor
Main Motor	24V (VA)	Main	24V (VA)	(A152 copier only)
				4th/5th Mirror Motor
Relay (RA402)		Board
Main Motor				(A152 copier only)

Quenching Lamp

Optics Cooling Fan

AC Drive Board

Motor (A152 copier only)

Document Feeder

Exhaust Blower

Motor

(Option)

5V (VC)

24V (VA)

AC power

DC Power

Image Density Sensor

DC power

5V (VC)

Supply Board

24V (VA)

Zero Cross

Scanner Motor

When this copier is plugged in and the main switch is turned off, ac power is supplied via the ac drive board to the optional anti-condensation heaters. When the front cover and/or the exit cover is open, the cover safety switch completely cuts off power to all ac and dc components. The RAM pack has a back up power supply (dc battery) for the service program mode data and misfeed job recovery.

When the main switch is turned on, the ac power supply to the anti-condensation heater is cut off and ac power is supplied to the ac drive board. The dc power supply board receives wall outlet ac power through the ac drive board.

The dc power supply board converts the wall outlet ac power input to +5 volts, +24 volts, and a zero cross signal, all of which are supplied to the main board.

1-14

24 June 1994

POWER DISTRIBUTION

The main board supplies dc power to all copier dc components. All sensors, switches, thermistors, and the DF interface board (option) operate on +5 volts. The operation panel operates on +5 volts supplied by the main board.

All other dc components including the power relay (RA401) and the main motor relay (RA402) operate on +24 volts.

When the main board receives power, it activates the power relay (RA401) which then supplies ac power to the fusing lamp drive circuit, and the exposure lamp drive circuit on the ac drive board. The fusing lamp drive circuit receives a trigger signal from the main board and the fusing lamp lights. The exposure lamp does not turn on until the main board sends a trigger pulse to the exposure lamp drive circuit.

When the Start key is pressed, the main board energizes the main motor relay (RA402). Then, the main motor and the quenching lamp turn on.

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

1-15

SECTION 2

DETAILED SECTION

DESCRIPTIONS

24 June 1994

DRUM

1. DRUM

1.1 DRUM CHARACTERISTICS

An organic photoconductor (OPC) drum is used in this model.

The OPC drum has the characteristics of:

1.Being able to accept a high negative electrical charge in the dark. (The electrical resistance of a photoconductor is high in the absence of light.)

2.Dissipating the electrical charge when exposed to light. (Exposure to light greatly increases the conductivity of a photoconductor.)

3.Dissipating an amount of charge in direct proportion to the intensity of the light. That is, where stronger light is directed to the photoconductor surface, a smaller voltage remains on the drum.

4.Being less sensitive to changes in temperature (when compared to selenium F type drums).

5.During the drum’s life, drum residual voltage gradually increases and the photoconductive surface becomes worn.

Therefore, some compensation for these characteristics is required.

2-1

DRUM	24 June 1994

1.2 DRUM UNIT

[E]

[A]

[G]

[F]

[C]

[D]

[B]

[C] [D]

The drum unit [A] consists of an OPC drum [B], ID sensor board [C] and a pick-off pawl [D]. When the drum, the pick-off pawl, or the ID sensor is replaced or cleaned, the drum unit must be removed from the copier. Therefore, the drum has a coupling device which is connected to the drum drive gear [E]. The ID sensor connector [F] is used for the ID sensor.

The main motor provides rotation directly to the drum through a series of gears.

The pick-off pawl [D] is always in contact with the drum surface.

2-2

24 June 1994 DRUM CHARGE

2. DRUM CHARGE

2.1 OVERVIEW	[C]

[A]

[B]

[D]

[D]

[A]

This copier uses a double wire scorotron and a highly sensitive OPC drum [A]. The corona wires [B] generate a corona of negative ions when the

CC/Grid/Bias power pack [C] applies a high voltage. The CC/Grid/Bias power pack also applies a negative high voltage to a stainless steel grid plate [D].

This insures that the drum coating receives a uniform negative charge as it rotates past the corona unit.

The exhaust fan, located above the copy exit, causes a flow of air from the upper area of the development unit through the charge corona unit. This prevents an uneven build-up of negative ions that can cause uneven image density. The exhaust fan runs at half speed when in the stand-by condition and at full speed while copying.

The exhaust fan has an ozone filter (active carbon) which adsorbs ozone (O3) generated by the charge corona. The ozone filter decreases in efficiency over time as it adsorbs ozone. The ozone filter should be replaced at every 80K copies.

The flow of air around the charge corona wires may deposit paper dust or toner particles on the corona wire. These particles may interfere with charging and cause low density bands on copies. The wire cleaner cleans the corona wire when the operator slides the corona unit out and in.

2-3

DRUM CHARGE

24 June 1994

2.2 CHARGE CORONA WIRE CLEANER MECHANISM

[B]

[A]

[D][C]

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

The cleaner pad bracket [B] rotates when the charge unit is fully extended and the bracket is pulled up against the rear endblock [C]. This moves the pads against the corona wires (see illustration). If the charge unit is not fully extended, the pads do not touch the corona wires.

The pads move away from the wires when the charge unit is fully inserted and the cleaning bracket is pushed against the front endblock [D].

After copier installation the key operator should be instructed to use this mechanism when copies have white streaks.

2-4

24 June 1994

DRUM CHARGE

2.3 CHARGE CORONA CIRCUIT

VA [24]	CN119-7	CN1-1	C	Charge Corona
	CN119-6	CN1-2
VC [5]
CC Trig [▼24]	CN119-5	CN1-3	Power Pack -
			CC/Grid/Bias G
				Grid
	CN119-3	CN1-5	(P1)
Grid Trig (PWM) [▲0→0/5]
	CN119-1	CN1-7	B
GND [0]
				Development
				Bias
Main Board (PCB 1)		t2
			PWM Duty cycle
		t1
			=t2/t1 x 100 (%)

The main board supplies +24 volts to the CC/Grid/Bias power pack at CN1-1 as the power supply source. After the Start key is pressed the CPU drops

CN1-3 from +24 volts to 0 volts. This energizes the charge corona circuit within the CC/Grid/Bias power pack, which applies a high negative voltage of approximately –7.0 K volts to the charge corona wires. The corona wires then generate a negative corona charge.

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

The grid trigger pulse applied to CN1-5 is a pulse width modulated signal (PWM signal). This signal is not only a trigger signal, it also changes the voltage level of the grid. As the width of the pulse applied increases, the voltage of the grid also increases.

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DRUM CHARGE

24 June 1994

2.4 GRID VOLTAGE CORRECTION

To maintain good copy quality over the drum’s life, the grid voltage is changed by the following:

∙Drum residual voltage correction (Vr correction)

∙Drum wear correction

2.4.1Drum Residual Voltage Correction (Vr correction)

During the drum’s life, the drum may fatigue electrically and residual voltage

(Vr) on the drum may gradually increase. When this happens, the corona charged voltage on the drum is not discharged enough in the quenching and exposure processes. Even if the development bias is applied in the development process, the background area of the original on the drum may attract some toner. This may cause dirty background on copies. The Vr correction prevents this phenomenon as follows:

A pattern (Vr pattern) is developed on the drum every 1,000 copies and its reflectivity is detected by the ID sensor to measure the residual voltage. This is called residual voltage detection. (If the reflectivity is low, the residual voltage will be high.) When the Vr pattern is developed, all blocks of the erase lamp turn on, and the development bias voltage is 0 volt.

The CPU determines what level of Vr correction is necessary depending on the output (Vr ratio [L]) from the ID sensor.

L = VsgVrp x 100 (%)

Vrp: ID sensor output for Vr pattern

Vsg: ID sensor output for bare drum

The current Vr ratio is displayed by SP67.

The CPU increases the development bias voltage depending on the Vr ratio to prevent dirty background on copies, (See page 2-30 for more information.)

The CPU also increases the grid voltage to ensure proper image density depending on the Vr ratio. (See page 2-8.)

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DRUM CHARGE

2.4.2 Drum Wear Correction

During the drum’s life, the photoconductive surface of the drum becomes worn by contact with the cleaning blade and developer on the development roller. This effects ability of the drum to hold a charge. This characteristic especially affects developing of the ID sensor pattern. The ID sensor pattern developed on the drum becomes lighter causing higher toner concentration in the developer. The drum wear correction is made to prevent this phenomenon and is as follows:

The CPU keeps track of the drum motor rotation time that corresponds to the wear of the photoconductive layer. The grid voltage for the toner density detection increases at set interval. The grid voltage for the residual voltage (Vr) detection also increases at the same interval. (See page 2-9.) The drum motor rotation time is displayed by SP57.

2.5 GRID VOLTAGE FOR IMAGE DENSITY CONTROL

The main board controls the grid voltage for the copy image through the CC/Grid/Bias power pack. As the grid voltage for the image density control becomes less, the copy image becomes lighter and vice versa.

The grid voltage is based on the standard grid voltage and correction factors as follows:

Grid Voltage = Standard image density grid voltage (–680 volts [SP60 = 4])

+

Vr correction factor

+

Auto image density level factor (SP34)

2.5.1 Standard Image Density Grid Voltage

The standard image density grid voltage (SP60) is set at the factory and the setting is different for each machine. The setting of SP60 is described on the SP mode data sheet located inside the inner cover of the machine.

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DRUM CHARGE 24 June 1994

2.5.2 Drum Residual Voltage (Vr) Correction Factor

Vr ratio (L) (%) (SP67)	Change of grid voltage (volts)
100 to 84	±0
83 to 58	–40
57 to 41	–80
40 to 28	–120
27 to 0	–160

L = Vrp/Vsg x 100 (%)

Vrp: ID sensor output for Vr pattern

Vsg: ID sensor output for bare drum

During the drum’s life, drum residual voltage (Vr) may gradually increase. Vr correction compensates for the residual voltage on the drum. The Vr correction is done every 1000 copies. The CPU increases the development bias voltage and the grid voltage. The above table shows how the grid voltage changes depending on the Vr ratio.

2.5.3 Auto Image Density Level Factor (SP34)

Auto image density level	Data (SP34)	Change of grid voltage (volts)
Normal	0 *	±0
Darker	1	–40
Lighter	2	±0

* Factory setting

The grid voltage and the exposure lamp voltage are constant regardless of the output from the auto image density sensor. Only the development bias voltage varies depending on the output from the auto image density sensor.

But only when the auto image density level data in SP34 is set to darker, the grid voltage is changed –40 volts as shown in the above table. When it is set to lighter, the grid voltage does not change. However, the development bias voltage is corrected.

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24 June 1994

DRUM CHARGE

2.6GRID VOLTAGE FOR TONER DENSITY DETECTION AND RESIDUAL VOLTAGE (Vr) DETECTION

The guid voltage is the same for both toner density detection and residual voltage correction.

Grid voltage = Standard ID sensor grid voltage (–460 volts [SP62=4])

+

Drum wear correction factor (SP57)

Drum Wear Correction Factor (SP57)

Main motor rotation time (SP57)	Change of grid voltage (volts)
0 to 2H	±0
2 to 65H	–20
65 to 112H	–40
112 to 157H	–60
More than 157H	–80

The grid voltage for toner density detection is the same as it is for the residual voltage (Vr) detection. However, the development bias voltage is different. (See page 2-30 and 2-35.)

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OPTICS

24 June 1994

3. OPTICS

3.1 OVERVIEW

[B]

[A]

[E]

[H]

[F]

[J]

[C]

[D]

[G]

[I]

During the copy cycle, an image of the original is reflected onto the drum surface through the optics assembly as follows.

Light Path:

Exposure Lamp [A] → Original → First Mirror [B] → Second Mirror [C]

→Third Mirror [D] → Lens [E] → Fourth Mirror [F]→ Fifth Mirror [G]

→Sixth Mirror [H] → Drum [I]

This copier has six standard reproduction ratios (A152 copier only), three reduction ratios, two enlargement ratios, and full size. It also has a zoom function. The operator can change the reproduction ratio in one percent steps from 61% to 141%.

Stepper motors are used to change the positions of the lens and mirrors (A152 copier only). Separate motors are used because the wide range of reproduction ratios makes it mechanically difficult for one motor to position both the lens and mirrors. A stepper motor is also used to drive the scanner. This motor changes the scanner speed according to the reproduction ratio.

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24 June 1994

OPTICS

The CPU monitors the temperature around the optics cavity through a thermistor which is located at the upper left rear side of the copier frame. When the temperature reaches 45°C, the optics cooling fan [J] (A152 copier only) starts rotating to draw cool air into the optics cavity. However, A151 copier is not equipped with a cooling fan. The machine will stop if the optics cavity overheats. (See page 6-52.) In this case, the Energy Saver indicator blinks and the Start key turns red.

The air flows from the right to the left, and exhausts through the vents in the left side of the upper cover. This fan operates until the temperature drops below 45°C.

The thermofuse provides back-up overheat protection. It opens at 128°C and removes ac power to the exposure lamp.

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