Ricoh AFICIO 200 Service Manual AD1

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 some components of the copier and the paper tray unit 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.If the Start key is pressed before the copier completes the warm-up period (the Start key starts blinking red and green alternatively), keep hands away from the mechanical and the electrical components as the copier starts making copies as soon as the warm-up period is completed.

6.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.

HEALTH SAFETY CONDITIONS

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

2.Always replace the ozone filters with the specified ones at the specified 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.

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.

2.The RAM board on the system control board has a lithium battery which can explode if replaced incorrectly. Replace the battery only with an identical one. The manufacturer recommends replacing the entire RAM board. Do not recharge or burn this battery. Used batteries must be handled in accordance with local regulations.

SAFETY AND ECOLOGICAL NOTES FOR DISPOSAL

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

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

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

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

LASER SAFETY

The Center for Devices and Radiological Health (CDRH) prohibits the repair of laser-based optical units in the field. The optical housing unit can only be repaired in a factory or at a location with the requisite equipment. The laser subsystem is replaceable in the field by a qualified Customer Engineer. The laser chassis is not repairable in the field. Customer engineers are therefore directed to return all chassis and laser subsystems to the factory or service depot when replacement of the optical subsystem is required.

WARNING

Use of controls, or adjustment, or performance of procedures other than those specified in this manual may result in hazardous radiation exposure.

WARNING FOR LASER UNIT

WARNING: Turn off the main switch before attempting any of the procedures in the Laser Unit section. Laser beams can seriously damage your eyes.

CAUTION MARKING:	!	INVISIBLE LASER RADIATION
		WHEN OPEN.
		AVOID DIRECT EXPOSURE TO
	DANGER	BEAM.
		>PS<
		INVISIBLE LASER RADIATION
	!	WHEN DISCONNECT OPTICAL
>P S <		FIBER CABLE.
		AVOID DIRECT EXPOSURE TO
	DANGER	BEAM.

>PS<

SECTION 1

OVERALL MACHINE

INFORMATION

1 August 1996 SPECIFICATIONS

1. SPECIFICATIONS

Configuration:	Desktop
Copy Process:	Dry electrostatic transfer system
Originals:	Sheet/Book
Original Size:	Maximum A3/11" x 17"
Copy Paper Size:	Maximum
	A3/11" x 17"
	Minimum
	A5/81/2" x 51/2" sideways (Paper tray)
	A6/51/2" x 81/2" lengthwise (By-pass)
Copy Paper Weight:	Paper tray:
	60 ~ 90 g/m2, 16 ~ 24 lb
	By-pass:
	60 ~ 157 g/m2, 16 ~ 42 lb
Reproduction Ratios:	5 Enlargement and 7 Reduction
		A4/A3 Version			LT/DLT Version
			400%		400%
			200%		200%
	Enlargement		141%		155%
			122%		129%
			115%		121%
	Full size		100%		100%
			93%		93%
			87%		85%
			82%		77%
	Reduction		71%		74%
			65%		65%
			50%		50%
			25%		25%
Zoom:	25% to 400% in 1% steps
Power Source:	120V/60 Hz:
	More than 12 A (for North America)
	220V ~ 240V/50 Hz:
	More than 7 A (for Europe)
	220V ~ 240V/60 Hz:
	More than 7 A (for Asia)

1-1

SPECIFICATIONS 1 August 1996

Power Consumption:

	Mainframe Only		Full System
	120V	220V ~ 240V	120V	220V ~ 240V
Maximum	Less than 1.1 kW	Less than 850 W	Less than 1.2 kW	Less than 1 kW
Copying	Approx. 470 W	Approx. 500 W	Approx. 500 W	Approx. 530 W
Warm-up	Approx. 1.0 kW	Approx. 750 W	Approx. 1.0 kW	Approx. 750 W
Stand-by	Approx. 130 W	Approx. 130 W	Approx. 140 W	Approx. 140 W
Auto Shut Off	Approx. 2.0 W	Approx. 2.2 W	Approx. 2.2 W	Approx. 2.4 W

NOTE: Full System: Mainframe + ADF + Paper Tray Unit + Duplex Tray + 1-bin Sorter

Noise Emission:

		Mainframe Only	Full System
1.	Sound Power Level
	Copying	61.5 dB(A)	64.5 dB(A)
	Stand-by	30.0 dB(A)	30.0 dB(A)
2.	Sound Pressure Level at the Operator Position
	Copying	47.5 dB(A)	52.0 dB(A)
	Stand-by	17.5 dB(A)	17.5 dB(A)

NOTE: The above measurements were made in accordance with ISO 7779. Full System: Mainframe + ADF + Paper Tray Unit + Duplex Tray + 1-bin Sorter

Dimensions (W x D x H): 550 x 580 x 652 mm (21.7" x 22.9" x 25.7") Measurement Conditions

1)With by-pass feed table closed

2)Without the optional paper tray unit

3)Without the ADF

	Weight:	Less than 57 kg (126 lb)
	Copying Speed in Multicopy mode (copies/minute):
		A4 sideways/	A3/11" x 17"	B4/81/2" x 14"
		11" x 81/2"
	No optional memory	15	9	10
	With 4MB or 8MB	20	11	12
	optional memory
	Warm-up Time	Less than 30 seconds (20°C, 68°F): 115V
		machine
		Less then 35 seconds (20°C, 68°F): 230V

machine

1-2

1 August 1996							SPECIFICATIONS
First Copy Time:			Less than 9.8 s (from 1st paper tray to face down
			copy tray)
			Less than 8.8 s (from 1st paper tray to face up
			copy tray)
Copy Number Input:			Ten-key pad, 1 to 99 (count up or count down)
Manual Image Density:			7 steps
Automatic Reset:			60 s is the standard setting; it can be changed
			with a UP mode.
Auto Shut Off			15 min. is the standard setting; it can be
			changed with a UP mode.
Copy Paper Capacity:			Paper Tray: 250 sheets
			Optional Paper Tray Unit: 500 sheets x 2
			Bypass: 100 sheets (A4, B5, A5, B6, 8.5 x 11",
				5.5 x 8.5")
				10 sheets (A3, B4, 11 x 17", 8 x 13")
				1 sheet (non-standard sizes)
Toner Replenishment:			Cartridge exchange (216 g/cartridge)
Toner Yield:			8 k copies (A4 sideways, 6% full black, 1 to 1
			copying, ADS mode)
Optional Equipment:			∙	Platen cover
			∙	Auto document feeder
			∙ Paper tray unit with two paper trays
			∙	1-bin sorter
			∙	Duplex unit
			∙	Key counter
			∙	Tray heater
			∙ Optical anti-condensation heater
Copy Tray Capacity			Face down mode: 500 sheets
			Face up mode:			100 sheets
Memory Capacity:
			Standard (4 MB)			Optional 4 MB	Optional 8 MB
Multi duplex copy				X		O	O
Sort, Rotate Sort		A4, LT		O		O	O
		B4, LG		X		O	O
		A3, DLT		X		O	O
Number of pages		A4 6%		35		99	99
		ITU-T#4		15		45	75
						X: Not AvailableO: Available

1-3

MACHINE CONFIGURATION

1 August 1996

2. MACHINE CONFIGURATION

A

D

B

E

C

F

A193V501.wmf

Version	Item	Machine Code	No.
Copier	Copier	A193	E
	ADF (Option)	A628	D
	Paper Tray Unit (Option)	G697	F
	Duplex Unit (Option)	G694	C
	1-bin Sorter (Option)	A629	B
	Platen Cover (Option)	A645
	Memory 4MB (Option)	A642-01
	Memory 8MB (Option)	A642-02
Fax	Fax Controller (Option)	A639-01 (115V),
		-02(230V),
		-03(France), -04 (TWN)
	Telephone (Option)	H160	A
	ISDN (Option)	A644-01(115V),
		-02(230V)
	HDD (Option)	A641
	Memory Card (Option)	H130-54
	Function Card (Option)	H130-52
	Page Memory (Option)	A640
Printer	Printer Controller (Option)	A643-00 (115V),
		-01(230V)
	PS Option (Option)	A643-02
	HDD (Option)	A643-03

1-4

1 August 1996

PAPER PATH

3. PAPER PATH

Optional 1-bin Sorter

Face Up	Face
	Down Tray
Tray

Optional

Duplex

Tray

Paper

Tray

Optional

Paper

Tray Unit

A193V005.wmf

1-5

MECHANICAL COMPONENT LAYOUT

1 August 1996

4. MECHANICAL COMPONENT LAYOUT

35 1

34

33

32

31

30

29

28

27

2	3	4	5	6	7	8	9	10	11
									12

13

14

15

16

17

18 19

20

A193V502.wmf

26	25	24	23	22	21

1-6

1 August 1996 MECHANICAL COMPONENT LAYOUT

1.	2nd Mirror		22.	Transfer Roller
2.	1st Mirror		23.	Separation Brush
3.	DF Exposure Glass		24.	Transport Vacuum Fan
4.	Xenon Lamp		25.	Pressure Roller
5.	Exposure Glass		26.	Hot Roller
6.	Original Width Sensors		27.	Fusing Exit Roller
7.	1st Mirror		28.	Left Vertical Door/Face Up
8.	Barrel Toroidal Lens (BTL)			Tray
9.	Original Length Sensors		29.	Junction Gate
10.		Lens	30.	Hot Roller Strippers
11.		SBU Board	31.	Left Vertical Roller
12.		Scanner Motor	32.	Lower Exit Sensor
13.		F-theta Mirror	33.	Polygonal Mirror Motor
14.		2nd Mirror (Laser Unit)	34.	3rd Mirror
15. PCU			35.	Face Down Tray
16.		Toner Bottle
17.		By-pass Feed Roller
18.		By-pass Table
19.		Relay Rollers
20.		Paper Feed Rollers
21.		Bottom Plate

1-7

ELECTRICAL COMPONENT DESCRIPTIONS

1 August 1996

5. ELECTRICAL COMPONENT DESCRIPTIONS

Refer to the electrical component layout and the point-to-point diagram on the waterproof paper in the pocket for the locations of these components.

	Symbol	Index	Description	Note
		No.
	Printed Circuit Boards
			High Voltage Supply	Supplies high voltage to the drum charge
	PCB1	54	Board	roller, development roller, transfer roller, and
				discharge brush.
	PCB2	50	Lamp Stabilizer	Provides dc power for the exposure lamp.
	PCB3	58	PSU	Provides dc power to the system and ac
				power to the fusing lamp.
	PCB4	61	LD Unit	Controls the laser diode.
	PCB5	62	Operation Panel	Controls the touch panel display and LED
				matrix, and monitors the key matrix.
	PCB6	51	SBU	Contains the CCD, and outputs a video
				signal to the BICU board.
	PCB7	55	IOCSS	Controls the mechanical parts of the printer.
	PCB8	52	BICU	Controls all copier functions both directly or
				through other control boards.
	PCB9	53	MSU	Compressed the image data, stores the
				data, and applies the image editing.
	Motors
	M1	45	Main	Drives the main body components.
	M2	36	Scanner Drive	Drives the 1st and 2nd scanners (dc stepper
				motor).
	M3	47	Transport Vacuum	Aids paper transportation from the transfer
			Fan	roller to the fusing unit.
	M4	49	Polygonal Mirror	Turns the polygonal mirror.
	M5	37	Toner Supply	Rotates the toner bottle to supply toner to
				the toner supply unit.
	M6	35	Exhaust Fan	Removes heat from around the fusing unit.
	Sensors
	S1	33	Upper Exit	Detects misfeeds.
	S2	31	Lower Exit	Detects misfeeds.
	S3	28	Left Vertical Door	Cuts the +5 and +24 Vdc power lines.
	S4	27	Left Door	Detects whether the left door is open or
				closed.
			Relay	Detects the leading edge of paper from the
	S5	17		paper tray and duplex unit to determine the
				stop timing of the paper feed clutch and
				duplex feed motor. Also detects misfeeds.
	S6	10	PCU	Detects when a new PCU is installed.
	S7	29	Fusing Exit	Detects misfeeds.

1-8

1 August 1996			ELECTRICAL COMPONENT DESCRIPTIONS
Symbol	Index	Description	Note
	No.
S8	9	Charge Roller H.P	Informs the CPU when the drum charge
			roller is at home position.
S9	14	Upper Tray Paper	Informs the CPU when the upper paper tray
		End	runs out of paper.
S10	15	Lower Tray Paper	Informs the CPU when the lower paper tray
		End	runs out of paper.
S11	16	By-pass Feed Paper	Informs the CPU when there is no paper in
		End	the by-pass tray.
		Registration	Detects the leading edge of the copy paper
S12	12		to determine the stop timing of the paper
			feed clutch, and detects misfeeds.
S13	11	By-pass Feed Paper	Detects the width of the paper in the by-pass
		Width	feed table.
S14	59	Humidity	Monitors the humidity around the PCU.
S15	4	Original Width	Detects the width of the original. This is one
			of the APS (Auto Paper Select) sensors.
S16	5	Original Length-1	Detects the length of the original. This is one
			of the APS (Auto Paper Select) sensors.
S17	6	Original Length-2	Detects the length of the original. This is one
			of the APS (Auto Paper Select) sensors.
		Platen Cover	Informs the CPU whether the platen cover is
S18	3		up or down (related to APS/ARE functions).
			ARE: Auto Reduce and Enlarge
S19	1	Scanner H.P.	Informs the CPU when the 1st and 2nd
			scanners are at the home position.
S20	23	Toner Density (TD)	Detects the amount of toner inside the
			development unit.
Switches
SW1	21	AC	Supplies power to the copier.
SW2	32	Main	Supplies power to operate the machine.
SW3	13	Right Vertical Guide	Cuts the +5 and +24 Vdc power lines.
SW4	20	Upper Paper Size	Determines what size of paper is in the
			upper paper tray.
SW5	19	Lower Paper Size	Determines what size of paper is in the lower
			paper tray.
		Front Door Safety	Cuts the +5VLD and +24V dc power lines
SW6	26		and detects whether the front cover is open
			or not.
Magnetic Clutches
MC1	46	Charge Roller Contact	Controls the touch and release movement of
			the drum charge roller.
MC2	42	Upper Relay	Drives the upper relay rollers.
MC3	43	Lower Relay	Drives the lower relay rollers.
MC4	40	By-pass Feed	Starts paper feed from the by-pass feed
			table.
MC5	41	Upper Paper Feed	Starts paper feed from the upper paper tray.

1-9

ELECTRICAL COMPONENT DESCRIPTIONS				1 August 1996
Symbol	Index	Description		Note
	No.
MC6	44	Lower Paper Feed		Starts paper feed from the lower paper tray.
MC7	39	Registration		Drives the registration rollers.
MC8	38	Development		Drives the development roller.
Solenoids
SOL1	48	Junction Gate		Moves the junction gate to direct copies to
				the face up or face down copy tray.
Lamps
L1	60	Quenching		Neutralizes any charge remaining on the
				drum surface after cleaning.
L2	2	Scanner		Applies light to the original for exposure.
L3	8	Fusing		Provides heat to the hot roller.
Heaters
		Tray (option)		Turns on when the main switch is off to keep
H1	18			paper in the paper tray dry. Tray heaters are
				also available for the optional paper feed unit.
H2	34	Anti-condensation		Turns on when the main switch is off to
		(option)		prevent moisture from accumulating.
Thermistors
TH1	24	Charge Roller		Monitors the temperature of the drum charge
				roller.
TH2	22	Fusing		Monitors the temperature of the hot roller.
Thermofuses
TF1	7	Fusing		Provides back-up overheat protection in the
				fusing unit.
Counters
CO1	25	Total		Keeps track of the total number of copies
				made.
CO2	---	Key		Used for control of authorized use. The
		(option)		copier will not operate until it is installed.
Others
		Laser		Detects the laser beam at the start of the
LSD1	30	Synchronization		main scan.
		Detector
NF	56	Noise Filter		Removes electrical noise from the AC input
		(230V machine only)		line.
CB	57	Circuit Breaker		Guards against voltage surges in the AC
		(230V machine only)		input line.

1-10

1 August 1996

DRIVE LAYOUT

6. DRIVE LAYOUT

1

2

3

10

9

8

7

4

A193V503.wmf

6 5

1.	Scanner Drive Motor	6.	Lower Paper Feed Clutch
2.	Development Clutch	7.	Lower Relay Clutch
3.	Charge Roller Contact	8.	Upper Relay Clutch
4.	Main Motor	9.	Upper Paper Feed Clutch
5.	Registration Clutch	10.	By-pass Feed Clutch

1-11

COPY PROCESS

1 August 1996

7. COPY PROCESS

7.1 OVERVIEW

1

A193V505.wmf

Pow er Pack

-1750 V
8	2

3

-90 V	-140 V
	-900 V
	4
	7

-600 V

6			5

	+2 kV	+15 μA
			Pow er Pack
			A193V506.wmf

1-12

1 August 1996

COPY PROCESS

1. EXPOSURE

A xenon lamp exposes the original. Light reflected from the original passes to the CCD, where it is converted into an analog data signal. This data is converted to a digital signal, processed, and stored in the memory. At the time of printing, the data is retrieved and sent to the laser diode. For multi-copy runs, the original is scanned once only and stored to the memory.

2. DRUM CHARGE

In the dark, the charge roller gives a negative charge to the organic photo-conductive (OPC) drum. The charge remains on the surface of the drum because the OPC layer has a high electrical resistance in the dark.

3. LASER EXPOSURE

The processed data scanned from the original is retrieved from the memory and transferred to the drum by a laser beam, which forms an electrical latent image on the drum surface. The amount of charge remaining as a latent image on the drum depends on the laser beam intensity, which is controlled by the BICU board.

4. DEVELOPMENT

The magnetic developer brush on the development rollers comes in contact with the latent image on the drum surface. Toner particles are electrostatically attracted to the areas of the drum surface where the laser reduced the negative charge on the drum.

5. IMAGE TRANSFER

Paper is fed to the area between the drum surface and the transfer roller at the proper time for aligning the copy paper and the developed image on the drum surface. Then, the transfer roller applies a high positive charge to the reverse side of paper. This positive charge produces an electrical force which pulls the toner particles from the drum surface on to the paper. At the same time, the paper is electrically attracted to the transfer roller.

6. PAPER SEPARATION

Paper separates from the drum as a result of the electrical attraction between the paper and the transfer roller. The discharge brush helps separate the paper from the drum.

7. CLEANING

The cleaning blade removes any toner remaining on the drum surface after the image is transferred to the paper.

8. QUENCHING

The light from the quenching lamp electrically neutralizes the charge on the drum surface.

1-13

BOARD STRUCTURE			1 August 1996
8. BOARD STRUCTURE
8.1 OVERVIEW
Scanner
Motor		Flat Cable	S B U
Scanner Sensors
		Harness	LD Unit
DF Motor
	IOCSS	BICU	Polygon
			Mirror
		Harness
DF Sensors,			Motor
Solenoids
Laser Printer		Laser Synchronization
		Signal = Optical Cable
Sensors, Solenoids,
Motors, Clutches
High Voltage Supply		MSU	Additional
			Memory
Peripheral Sensors,
Motors, Solenoids,
Clutches
Operation	Harness
Panel
		Flat Cable
	Fax Controller	Mother Board

Printer

Controller

Standard Option

A193V504.wmf

1-14

1 August 1996

BOARD STRUCTURE

8.2 DESCRIPTION

1. BICU (Base Engine and Image Control Unit)

This is the main board. It controls the following functions:

∙Engine sequence

∙Scanner, laser printer engine

∙Timing control for peripherals

∙Image processing, video control

∙Operation control

∙Corresponding application boards

∙Machine control, system control

2. IOCSS (I/O and Customer Support System Unit)

The IOCSS board handles the following functions:

∙Drive control for the sensors, motors, solenoids of the printer and scanner

∙PWM control for the high voltage control board

∙Serial interfaces with peripherals

∙Circuit for fusing control

3. SBU (Sensor Board Unit)

The SBU deals with the analog signals from the CCD and converts them into digital signals.

4. MSU (Memory Super-charger Unit)

The MSU stores and compresses the image data. It also does image editing on the data if requested by the user. An extra 4 MB or 8 MB of memory can be added (see below).

5. Additional Memory (Option)

This is an additional image memory board for the MSU.

6. LD Unit

This is the laser diode drive circuit board.

7. Mother Board

This is the printer control board as well as the BICU interface board. It receives the signals from the printer control board and sends signals to the printer control board.

1-15

SECTION 2

DETAILED SECTION DESCRIPTIONS

1 August 1996

SCANNING

1. SCANNING

1.1OVERVIEW

[E][A]

A193D001.wmf

[G]

[F] [D]

[C]

[B]

The original is illuminated by the exposure lamp (a xenon lamp in this model) [A]. The image is reflected onto a CCD (charge coupled device) [B] via the 1st, 2nd, 3rd mirrors, and lens [C].

The 1st scanner [D] consists of the exposure lamp, a reflector [E], and the 1st mirror [F].

The exposure lamp is energized by a dc supply to avoid uneven light intensity as the 1st scanner moves in the sub scan direction. The entire exposure lamp surface is frosted to ensure even exposure in the main scan direction.

The light reflected by the reflector is of almost equal intensity, to reduce shadows on pasted originals.

An optics anti-condensation heater [G] is available as an option. It can be installed on the left side of the inner cover. It turns on whenever the power cord is plugged in.

2-1

SCANNING 1 August 1996

	1.2 SCANNER DRIVE	[H]
	[B]	[G]
		[A]

[E]

[D]

[G]	[F]	[C]
	[E]
		A193D546.wmf

A stepper motor is used to drive the scanner. The 1st and 2nd scanners [A,B] are driven by this scanner drive motor [C] through the timing belt [D], scanner drive pulley [E], scanner drive shaft [F], and two scanner wires [G].

– Book mode –

The scanner drive board controls and operates the scanner drive motor. In full size mode, the 1st scanner speed is 90 mm/s during scanning. The 2nd scanner speed is half that of the 1st scanner.

In reduction or enlargement mode, the scanning speed depends on the magnification ratio (M: 0.25 to 4.00). The returning speed is always the same, whether in full size or magnification mode. The image length change in the sub scan direction is done by changing the scanner drive motor speed, and in the main scan direction it is done by image processing on the BICU board.

Magnification in the sub-scan direction can be adjusted by changing the scanner drive motor speed using SP4-101. Magnification in the main scan direction can be adjusted using SP4-008.

– ADF mode –

The scanners are always kept at their home position (the scanner H.P sensor [H] detects the 1st scanner) to scan the original. The ADF motor feeds the original through the ADF. In reduction/enlargement mode, the image length change in the sub-scan direction is done by changing the ADF motor speed. Magnification in the main scan direction is done in the BICU board, like for book mode.

Magnification in the sub-scan direction can be adjusted by changing the ADF motor speed using SP6-007. In the main scan direction, it can be adjusted with SP4-008, like for book mode.

2-2

1 August 1996

SCANNING

1.3ORIGINAL SIZE DETECTION IN PLATEN MODE

[B]

[C]

A193D526.wmf

[A]

A193D003.wmf

In the optics cavity for original size detection, there are four reflective sensors in the 115V machines, and six reflective sensors in the 230V machines. The Original Width Sensors [A] detect the original width, and the Original Length Sensors [B] detect the original length. These are the APS (Auto Paper Select) sensors. Each APS sensor is a reflective photosensor.

While the main switch is on, these sensors are active and the original size data is always sent to the CPU. However, the CPU checks the data only when the platen cover is opened.

The original size data is taken by the main CPU when the platen cover sensor [C] is activated. This is when the platen is positioned about 15 cm above the exposure glass. At this time, only the sensor(s) located underneath the original receive the reflected light and switch on. The other sensor(s) are off. The main CPU can recognize the original size from the on/off signals from the APS sensors.

If the copy is made with the platen fully open, the main CPU decides the original size from the sensor outputs when the Start key is pressed.

2-3

SCANNING								1 August 1996
Original Size			Length Sensors					Width
								Sensors
A4/A3 version	LT/DLT version	L1		L2	L3		L4	S1	S2
A3	11" x 17"	O		O	O		O	O	O
B4	10" x 14"	O		O	O		O	O	X
F4	81/2" x 14" (8" x 13")	O		O	O		X	X	X
A4–L	81/2" x 11"	O		O	X		X	X	X
B5–L	—	O		X	X		X	X	X
A4–S	11" x 81/2"	X		X	X		X	O	O
B5–S	—	X		X	X		X	O	X

O: ON X: OFF

NOTE: The length sensors L3 and L4 are used only for 230V machines.

For other combinations, "CANNOT DETECT ORIG. SIZE" will be indicated on the operation panel display.

The above table shows the outputs of the sensors for each original size. This original size detection method eliminates the necessity for a pre-scan and increases the machine’s productivity.

However, if the by-pass feeder is used, note that the machine assumes that the copy paper is lengthwise. For example, if A4 sideways paper is placed on the by-pass tray, the machine assumes it is A3 paper and scans the full A3 area, disregarding the original size sensors. This can cause excess toner to be transferred to the transfer roller, so users should be instructed to always set the paper lengthwise on the by-pass tray. This problem occurs for the first page only. The registration sensor detects the length of the first page, and will assume that the following sheets of copy paper are the same length.

Original size detection using the ADF is described in the manual for the ADF.

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1 August 1996

IMAGE PROCESSING

2. IMAGE PROCESSING

2.1OVERVIEW

			C D	S B U
			C
					Fax Controller
			L D		TX
	D r u m	LD Driver	Controller		IPU
			(GAVD)		M S U
					FCI
					Printer
		L D D R	BICU	RX	Controller
			Fax
			Controller
					A193D501.wmf

The CCD generates an analog video signal. The SBU (Sensor Board Unit) converts the analog signal to an 8-bit digital signal, then it sends the digital signal to the BICU (Base-engine and Image Control Unit) board.

The BICU board can be divided into three image processing blocks; the IPU (Image Processing Unit), FCI (Fine Character Image), and LD controller (GAVD)

∙IPU: Auto shading, filtering, magnification, γ correction, and gradation processing

∙FCI: Smoothing (binary picture processing mode only)

∙LD controller: LD print timing control and laser power PWM control

Finally, the BICU board sends the video data to the LD drive board at the correct time.

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IMAGE PROCESSING

1 August 1996

2.2SBU (SENSOR BOARD UNIT)

	Amp .	SBU	BICU
O D D	Z/C
C C D
E V E N	Z/C
		A/D	IPU
	A G C	Vin
	Reference	ref
	Controller
	Analog
	Processing IC

Z/C: Zero Clamp

AGC: Automatic Gain Control Circuit

A193D502.wmf

The CCD converts the light reflected from the original into an analog signal. The CCD line has 5,000 pixels and the resolution is 400 dpi (15.7 lines/mm).

The CCD has two output lines, for odd and even pixels, to the analog processing IC. The analog processing IC performs the following operations on the signals from the CCD:

1) Z/C (Zero Clamp):

Adjusts the black level reference for even pixels to match the odd pixels.

2) Signal Composition:

Analog signals for odd and even pixels from the CCD are merged by a switching device.

3) Signal Amplification

The analog signal is amplified by operational amplifiers in the AGC circuit. The maximum gains of the operational amplifiers are controlled by the CPU on the BICU board.

After the above processing, the analog signals are converted to 8-bit signals by the A/D converter. This will give a value for each pixel on a scale of 256 grades. Then, the digitized image data goes to the BICU board.

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1 August 1996

IMAGE PROCESSING

2.3AUTO IMAGE DENSITY (ADS)

[A]

Sub scan direction

A193D004.wmf

This mode prevents the background of an original from appearing on copies.

The copier scans the auto image density detection area [A] as shown in the diagram. This corresponds to a few mm at one end of the main scan line. As the scanner scans down the page, the IPU on the BICU detects the peak white level for each scan line. The IPU determines the reference value for the A/D conversion for a particular scan line using the peak white level for that scan line. Then, the IPU sends the reference value data to the reference controller on the SBU.

When an original with a gray background is scanned, the density of the gray area is the peak white level density. Therefore, the original background will not appear on copies. Because peak level data is taken for each scan line, ADS corrects for any changes in background density down the page.

As with previous digital copiers, the user can select manual image density when selecting auto image density mode, and the machine will use both settings when processing the original.

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IMAGE PROCESSING

1 August 1996

2.4IPU (IMAGE PROCESSING UNIT)

2.4.1 Overview

		BICU
S B U	+	Tx
		Fax controller
	IPU	CP U BUS
M S U		CPU
	+
	+
L D	G A V D	FCI
Unit			1 bit
	+	+	Data
		+	8 bit
Printer			Data
	Rx
controller
	Fax Controller

A193D527.wmf

The image data from the SBU goes to the IPU (Image Processing Unit) IC on the BICU board, which carries out the following processes on the image data:

1.Auto shading

2.Filtering (MTF and smoothing)

3.Magnification

4.γ correction

5.Grayscale processing

6.Binary picture processing

7.Error diffusion

8.Dithering

9.Video path control

10.Test pattern generation

The image data then goes to either the LD controller (GAVD) or the FCI depending on the selected copy modes.

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1 August 1996

IMAGE PROCESSING

2.4.2 Image Processing Path

SBU

Text mode			ADS and Auto		IPU
			Shading
Text/Photo
m o d e	Photo mode

	MTF	Smoothing
	Correction
		Main Scan
		Magnification/
		Reduction
		γ Correction
		(Scanner)

Grayscale

Processing

Dithering Error Diffusion

Binary Picture

Processing

Line Width

Correction

Image Compression/ M S U

Fax Controller Decompression, Image

Rotation/Adjust Image

Printer

Video Path Controller

Controller

FCI

Edge Smoothing

Line Width Correction

Laser Diode Power

Modulation

γ Correction (Printer)

BICU

L D D R

A193D506.wmf

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IMAGE PROCESSING

1 August 1996

2.4.3 Auto Shading

A193D517.wmf

As with the previous digital copiers, there are two auto shading methods. One is black level correction and the other is white level correction. Auto shading corrects errors in the signal level for each pixel.

1) Black Level Correction

The CPU reads the black dummy data from one end of the CCD signal (64 pixels at the end are blacked off) and takes the average of the black dummy data. Then, the CPU deletes the black level value from each image pixel.

2) White Level Correction

Before scanning the original, the machine reads a reference waveform from the white plate. The average of the white video level for each pixel is stored as the white shading data in the FIFO memory in the IPU chip.

The video signal information for each pixel obtained during image scanning is corrected by the IPU chip.

In book mode, auto shading is done at the beginning of each scan.

In ADF mode, auto shading is done at a specific time interval. This interval can be set with SP4-913 (the default setting is 30 seconds). The machine waits until the end of the page before doing the auto shading.

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1 August 1996

IMAGE PROCESSING

2.4.4 Filtering and Main Scan Magnification/Reduction

1. Overview

After auto shading, the image data is processed by both filtering and main scan magnification. However, to reduce the occurrence of moire in the image, the processing order is different depending on the reproduction ratio, as follows.

1) Reduction and Full size

Main Scan Reduction → Filtering 2) Enlargement

Filtering → Main Scan Magnification

2. Filtering

There are two software filters for enhancing the desired image qualities of the selected original mode: the MTF filter and the smoothing filter.

The MTF filter emphasizes sharpness and is used in Text and Text/Photo modes. The smoothing filter is used in Photo mode.

The relationships between the coefficient of the filter and the filter strengths are as follows. Note that these relationships are for copier mode only. Fax mode has its own unique table. (Refer to the fax section.)

The filter strengths for each mode can be adjusted with SP4-407.

NOTE: Never select "1." Abnormal images may result.

A193D503.wmf

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