Ricoh Ft7950 Service Manual

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Page 1

Penguin Series

Little/Crest/Emperor

(Machine Code: A246/A247/ A248)

Service Manual

Page 2

IMPORTANT SAFETY NOTICES

1. OVERALL MACHINE INFORMATION 1-1..........................

1.1 SPECIFICATION 1-1......................................................

1.2 MACHINE CONFIGURATION 1-6..................................

1.2.1 COPIER OVERVIEW 1-6.....................................................

1.2.2 SYSTEM OVERVIEW 1-6....................................................

1.3 COPY PROCESS AROUND THE DURM 1-8................

1.4 MECHANICAL COMPONENT LAYOUT 1-10..................

1.5 DRIVE LAYOUT 1-12.......................................................

1.6 PAPER PATH 1-13...........................................................

1.6.1 STANDARD COPYING 1-13.................................................

1.6.2 MULTIPLE 2-SIDE COPYING 1-14.......................................

1.7 ELECTRICAL COMPONENT DESCRIPTION 1-15.........

2. DETAILED SECTION DESCRIPTIONS 2-1........................

2.1 PROCESS CONTROL 2-1..............................................

2.1.1 OVERVIEW 2-1...................................................................

2.1.2 PROCESS CONTROL DATA INITIAL SETTING 2-4..........

2.1.3 LATENT IMAGE CONTROL 2-5..........................................

2.1.4 IMAGE DENSITY CONTROL 2-12........................................

2.2 DRUM UNIT 2-18..............................................................

2.2.1 OVERVIEW 2-18...................................................................

2.2.2 OPC DRUM CHARACTERISTICS 2-19................................

2.2.3 DRUM CHARGE 2-20............................................................

2.2.4 ERASE 2-23...........................................................................

2.2.5 CLEANING 2-25....................................................................

2.2.6 QUENCHING 2-30.................................................................

2.3 DRUM CLEANING AND TONER-RECYCLING 2-31.......

2.3.1 TONER TRANSPORT 2-31...................................................

2.3.2 FILTERING 2-32....................................................................

2.3.3 PUMP MECHANISM 2-33.....................................................

2.3.4 DRIVE MECHANISM 2-34.....................................................

2.3.5 TONER COLLECTION BOTTLE 2-35...................................

2.4 OPTICS 2-36....................................................................

2.4.1 OVERVIEW 2-36...................................................................

2.4.2 SCANNER DRIVE 2-37.........................................................

2.4.3 VERTICAL LENS DRIVE 2-38...............................................

2.4.4 HORIZONTAL LENS DRIVE 2-39.........................................

2.4.5 HORIZONTAL LENS POSITIONING 2-40.............................

2.4.6 3 SCANNER DRIVE 2-42......................................................

2.4.7 OPTICS CONTROL CIRCUIT 2-43.......................................

2.4.8 AUTOMATIC IMAGE DENSITY CONTROL 2-44..................

2.4.9 MANUAL IMAGE DENSITY CONTROL 2-46........................

2.4.10 UNEVEN LIGHT INTENSITY CORRECTION 2-47.............

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2.4.11 ORIGINAL SIZE DETECTION IN PLATEN MODE 2-48......

2.4.12 HALF TONE MODE 2-50.....................................................

2.5 DEVELOPMENT 2-51.......................................................

2.5.1 OVERVIEW 2-51...................................................................

2.5.2 DEVELOPMENT MECHANISM 2-52.....................................

2.5.3 DRIVE MECHANISM 2-53.....................................................

2.5.4 CROSSMIXING 2-54.............................................................

2.5.5 DEVELOPMENT BIAS 2-55..................................................

2.5.6 TONER SUPPLY 2-60...........................................................

2.6 IMAGE TRANSFER 2-64..................................................

2.6.1 PRE-TRANSFER LAMP 2-64................................................

2.6.2 IMAGE TRANSFER AND PAPER SEPARATION 2-65.........

2.6.3 IMAGE TRANSFER AND PAPER SEPARATION 2-66.........

2.6.4 TRANSFER BELT UNIT LIFT MECHANISM 2-68.................

2.6.5 PAPER TRANSPORTATION AND BELT DRIVE 2-69..........

2.6.6 TRANSFER BELT CLEANING MECHANISM 2-70...............

2.6.7 TONER COLLECTION MECHANISM 2-71...........................

2.6.8 TRANSFER ANTI-CONDENSATION HEATER 2-72.............

2.7 PAPER FEED 2-73...........................................................

2.7.1 OVERVIEW 2-73...................................................................

2.7.2 FRR FEED SYSTEM 2-74.....................................................

2.7.3 SLIP CLUTCH MECHANISM 2-76........................................

2.7.4 FRR FEED DRIVE MECHANISM 2-77..................................

2.7.5 SEPARATION ROLLER RELEASE MECHANISM 2-79........

2.7.6 PAPER RETURN MECHANISM 2-80....................................

2.7.7 PAPER SKEW PREVENTION MECHANISM 2-81................

2.7.8 PAPER LIFT MECHANISM 2-82...........................................

2.7.9 PAPER NEAR END/PAPER END DETECTION 2-85............

2.7.10 TANDEM FEED TRAY 2-86................................................

2.7.11 PAPER SIZE DETECTION 2-90..........................................

2.7.12 VERTICAL TRANSPORT MECHANISM 2-91.....................

2.7.13 TRAY POSITIONING MECHANISM 2-92............................

2.7.14 BY-PASS FEED TABLE 2-95..............................................

2.7.15 PAPER REGISTRATION 2-98.............................................

2.7.16 REGISTRATION DRIVE MECHANISM 2-99.......................

2.7.17 GUIDE PLATE RELEASE MECHANISM 2-100....................

2.8 IMAGE FUSING 2-101........................................................

2.8.1 OVERVIEW 2-101...................................................................

2.8.2 FUSING ENTRANCE GUIDE 2-102........................................

2.8.3 FUSING DRIVE MECHANISM 2-103......................................

2.8.4 FUSING LAMP CONTROL 2-104............................................

2.8.5 INVERTER AND PAPER EXIT 2-105......................................

2.8.6 INVERTER AND EXIT DRIVE MECHANISM 2-106................

2.9 DUPLEX 2-107...................................................................

2.9.1 OVERVIEW 2-107...................................................................

2.9.2 DRIVE MECHANISM 2-108.....................................................

2.9.3 DUPLEX ENTRANCE TO DUPLEX TRAY 2-109....................

2.9.4 DUPLEX STACKING 2-110.....................................................

2.9.5 DUPLEX PICK-UP ROLLER MECHANISM 2-111..................

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2.9.6 DUPLEX PAPER FEED 2-112.................................................

2.10 ENERGY STAR COMPLIANT MACHINES (ALL 2-115....

2.11 ENERGY SAVING INFORMATION 2-117........................

2.11.1 ABOUT THE ENERGY SAVING FEATURES OF 2-117.......

3. INSTALLATION PROCEDURE 3-1......................................

3.1 INSTALLATION REQUIREMENTS 3-1..........................

3.1.1 ENVIRONMENT 3-1............................................................

3.1.2 MACHINE LEVEL 3-1..........................................................

3.1.3 MINIMUM SPACE REQUIREMENTS 3-2...........................

3.1.4 POWER REQUIREMENTS 3-2...........................................

3.2 COPIER (A246/A247/A248) 3-3.....................................

3.2.1 ACCESSORY CHECK 3-3...................................................

3.2.2 INSTALLATION PROCEDURE 3-4.....................................

3.2.3 GUIDANCE ROM INSTALLATION (OPTION: 3-14...............

3.2.4 PLATEN COVER (OPTION) INSTALLATION 3-15...............

3.2.5 KEY COUNTER HOLDER INSTALLATION 3-16..................

3.2.6 ORIGINAL TRAY INSTALLATION (OPTION) 3-18...............

3.3 UNIVERSAL TRAY (TRAY 2) 3-19..................................

3.4 550 SHEETS PAPER TRAY (TRAY 3) 3-20....................

3.5 TANDEM FEED TRAY PAPER SIZE CHANGE 3-22......

3.6 DUAL JOB FEEDER (A610) 3-25....................................

3.6.1 ACCESSORY CHECK 3-25...................................................

3.6.2 INSTALLATION PROCEDURE 3-26.....................................

3.7 SORTER STAPLER (A821) 3-29.....................................

3.7.1 ACCESSORY CHECK 3-29...................................................

3.7.2 INSTALLATION PROCEDURE 3-30.....................................

3.7.3 SORTER ADAPTER INSTALLATION (OPTION) 3-34..........

3.8 20 BIN SORTER STAPLER (A658) (A246 ONLY) 3-36..

3.8.1 ACCESSORY CHECK 3-36...................................................

3.8.2 INSTALLATION PROCEDURE 3-37.....................................

3.9 LCT (A822) 3-41...............................................................

3.9.1 ACCESSORY CHECK 3-41...................................................

3.9.2 INSTALLATION PROCEDURE 3-42.....................................

3.9.3 PAPER SIZE CHANGE 3-46.................................................

3.10 TRANSPORTATION REMARKS 3-49............................

3.10.1 TONER RECYCLING TUBE CLEANING 3-49....................

3.10.2 OTHER OPERATIONS 3-49................................................

4. SERVICE TABLES 4-1.........................................................

4.1 GENERAL CAUTIONS 4-1.............................................

4.1.1 DRUM 4-1............................................................................

4.1.2 DRUM UNIT 4-1...................................................................

4.1.3 CHARGE CORONA 4-2......................................................

4.1.4 OPTICS 4-2.........................................................................

4.1.5 ERASE LAMP 4-3................................................................

4.1.6 DEVELOPMENT UNIT 4-3..................................................

4.1.7 TRANSFER BELT UNIT 4-3................................................

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4.1.8 CLEANING SECTION 4-4...................................................

4.1.9 PRE-TRANSFER LAMP 4-4................................................

4.1.10 PAPER FEED 4-4..............................................................

4.1.11 FUSING UNIT 4-4..............................................................

4.1.12 USED TONER 4-5.............................................................

4.2 SERVICE PROGRAM MODE 4-6..................................

4.2.1 SERVICE PROGRAM MODE OPERATION 4-6.................

4.2.2 SERVICE PROGRAM MODE TABLES 4-8.........................

4.2.3 INPUT CHECK 4-45..............................................................

4.2.4 OUTPUT CHECK 4-48..........................................................

4.3 USER PROGRAM 4-51....................................................

4.3.1 HOW TO ENTER AND EXIT UP MODE 4-51.......................

4.3.2 UP MODE TABLE 4-51..........................................................

4.4 TEST POINTS/DIP SWITCHES/LEDS 4-53....................

4.4.1 DIP SWITCHES 4-53.............................................................

4.4.2 TEST POINTS 4-53...............................................................

4.4.3 FUSES 4-54...........................................................................

4.4.4 LEDS 4-54.............................................................................

4.5 SPECIAL TOOLS AND LUBRICANTS 4-54.....................

4.5.1 SPECIAL TOOLS 4-54..........................................................

4.5.2 LUBRICANTS 4-54................................................................

4.6 TOUCH PANEL DISPLAY POSITION 4-55.....................

5. PREVENTIVE MAINTENANCE SCHEDULE 5-1................

5.1 PM TABLE 5-1................................................................

5.2 PM PROCEDURE 5-5....................................................

5.2.1 CLEARING PM COUNTER 5-5...........................................

5.2.2 PM PROCEDURE 5-6.........................................................

6. REPLACEMENT AND ADJUSTMENT 6-1.........................

6.1 EXTERIOR AND INNER COVER REMOVAL 6-1.........

6.1.1 FRONT COVER 6-1.............................................................

6.1.2 REAR SIDE 6-2...................................................................

6.1.3 INNER COVER 6-3..............................................................

6.1.4 RIGHT SIDE 6-6..................................................................

6.1.5 LEFT SIDE 6-7.....................................................................

6.1.6 OPERATION PANEL 6-8.....................................................

6.1.7 UPPER COVER 6-9.............................................................

6.2 PAPER FEED 6-10...........................................................

6.2.1 PAPER TRAY UNIT REMOVAL 6-10....................................

6.2.2 PAPER TRAY REMOVAL 6-13.............................................

6.2.3 PAPER FEED ROLLERS REPLACEMENT 6-16..................

6.2.4 PAPER FEED TIMING ADJUSTMENT 6-17.........................

6.2.5 PAPER FEED CLUTCH REMOVAL (1ST TRAY 6-20...........

6.2.6 REAR FENCE RETURN SENSOR REPLACEMENT 6-24....

6.2.7 REAR FENCE HP SENSOR REPLACEMENT 6-25..............

6.2.8 BOTTOM PAPER SENSOR REPLACEMENT 6-26..............

6.2.9 BY-PASS FEED TABLE REMOVAL 6-27..............................

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6.2.10 BY-PASS FEED ROLLERS REPLACEMENT 6-28.............

6.2.11 BY-PASS PAPER SIZE SENSOR REPLACEMENT 6-29...

6.2.12 BY-PASS FEED CLUTCH AND GUIDE PLATE 6-31..........

6.2.13 REGISTRATION MOTOR REMOVAL 6-33.........................

6.2.14 PAPER DUST CLEANER CLEANING 6-34........................

6.2.15 REGISTRATION SENSOR CLEANING 6-35......................

6.2.16 UNIVERSAL TRAY SIZE SWITCH REPLACEMEN 6-36....

6.2.17 550-SHEET TRAY SET SWITCH REPLACEMENT 6-37....

6.2.18 LIFT MOTOR REMOVAL 6-38............................................

6.2.19 PAPER FEED MOTOR REMOVAL 6-39.............................

6.2.20 COPIER FEED UNIT REMOVAL 6-40................................

6.2.21 BOTTOM PLATE LIFT WIRE REPLACEMENT 6-42..........

6.2.22 550 SHEETS PAPER TRAY (TRAY 3) 6-44........................

6.2.23 TANDEM FEED TRAY PAPER SIZE CHANGE 6-46..........

6.3 OPTICS 6-49....................................................................

6.3.1 EXPOSURE GLASS REMOVAL 6-49...................................

6.3.2 EXPOSURE LAMP REPLACEMENT 6-50............................

6.3.3 OPTICS THERMOSWITCH REPLACEMENT 6-52...............

6.3.4 SCANNER HP SENSOR REPLACEMENT 6-53...................

6.3.5 ADS SENSOR REMOVAL 6-54.............................................

6.3.6 SCANNER DRIVE MOTOR 6-55...........................................

6.3.7 SCANNER DRIVE WIRES REPLACEMENT 6-56.................

6.3.8 THIRD SCANNER REMOVAL 6-72.......................................

6.3.9 THIRD SCANNER DRIVE MOTOR/HP SENSOR 6-73.........

6.3.10 LENS HORIZONTAL DRIVE HP SENSOR 6-75.................

6.3.11 LENS HORIZONTAL DRIVE MOTOR 6-77.........................

6.3.12 APS SENSOR ADJUSTMENT (SENSITIVITY 6-79...........

6.3.13 ARS SENSOR ADJUSTMENT 6-80....................................

6.4 TONER RECYCLING 6-81...............................................

6.4.1 TONER RECYCLING UNIT REMOVAL 6-81........................

6.4.2 TONER RECYCLING CLUTCH REPLACEMENT 6-82.........

6.5 DEVELOPMENT AND TONER SUPPLY 6-83................

6.5.1 DEVELOPMENT UNIT REMOVAL 6-83................................

6.5.2 DEVELOPER REPLACEMENT 6-85.....................................

6.5.3 DEVELOPMENT ROLLERS REPLACEMENT 6-87..............

6.5.4 TONER DENSITY SENSOR REPLACEMENT 6-89..............

6.5.5 TONER BOTTLE DRIVE MOTOR REPLACEMENT 6-90.....

6.5.6 DEVELOPMENT FILTER AND PRESSURE 6-91.................

6.5.7 DEVELOPMENT ROLLER SHAFT CLEANING 6-92............

6.6 DRUM UNIT 6-93..............................................................

6.6.1 DRUM UNIT REMOVAL AND OPC DRUM 6-93...................

6.6.2 QUENCHING LAMP REPLACEMENT 6-94..........................

6.6.3 GRID PLATE/CHARGE WIRE/WIRE CLEANER 6-95.........

6.6.4 ERASE LAMP AND DRUM POTENTIAL SENSOR 6-97......

6.6.5 CLEANING BLADE REPLACEMENT 6-98............................

6.6.6 CLEANING BRUSH REPLACEMENT 6-99...........................

6.6.7 PICK-OFF PAWL REPLACEMENT 6-100...............................

6.6.8 OZONE FILTER REPLACEMENT 6-101.................................

6.6.9 PRE-TRANSFER LAMP REMOVAL 6-102.............................

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6.7 TRANSFER BELT UNIT 6-103..........................................

6.7.1 TRANSFER BELT UNIT REMOVAL/INSTALLATION 6-103...

6.7.2 TRANSFER BELT REPLACEMENT 6-105.............................

6.7.3 CLEANING BLADE REPLACEMENT 6-107............................

6.8 FUSING UNIT 6-108...........................................................

6.8.1 FUSING UNIT REMOVAL 6-108.............................................

6.8.2 FUSING THERMISTOR REPLACEMENT 6-109.....................

6.8.3 FUSING THERMOFUSE REPLACEMENT 6-110...................

6.8.4 FUSING LAMP REPLACEMENT 6-111..................................

6.8.5 OIL SUPPLY/CLEANING ROLLER REPLACEMENT 6-113...

6.8.6 OIL SUPPLY CLEANING BRUSH REPLACEMENT 6-114.....

6.8.7 HOT ROLLER REPLACEMENT 6-115....................................

6.8.8 PRESSURE ROLLER AND BEARING 6-117..........................

6.8.9 FUSING STRIPPER PAWL REPLACEMENT 6-119...............

6.8.10 FUSING PRESSURE ADJUSTMENT 6-120.........................

6.8.11 PAPER EXIT UNIT REMOVAL 6-121....................................

6.8.12 EXIT SENSOR AND FUSING EXIT SENSOR 6-123............

6.8.13 DUPLEX PAPER GUIDE SENSOR AND 6-124....................

6.8.14 PRESSURE ROLLER CLEANING ROLLER 6-125...............

6.9 DUPLEX UNIT 6-126..........................................................

6.9.1 FEED ROLLER REPLACEMENT 6-126..................................

6.9.2 SEPARATION BELT REPLACEMENT 6-128..........................

6.9.3 DUPLEX UNIT REMOVAL 6-131............................................

6.9.4 SEPARATION CLUTCH/TRANSPORT CLUTCH 6-132.........

6.9.5 JOGGER MOTOR REPLACEMENT 6-133.............................

6.10 COPY QUALITY ADJUSTMENT 6-138............................

6.10.1 SP ADJUSTMENT MODE 6-138...........................................

6.10.2 SIDE-TO-SIDE REGISTRATION ADJUSTMENT 6-140........

6.10.3 UNEVEN EXPOSURE ADJUSTMENT 6-141........................

6.10.4 IMAGE DENSITY ADJUSTMENT 6-143...............................

6.10.5 SCANNER HEIGHT ADJUSTMENT 6-144...........................

6.10.6 APS SIZE CALIBRATION 6-145............................................

6.10.7 FUSING EXIT COVER MAGNET POSITIONING 6-146.......

7. TROUBLESHOOTING 7-1...................................................

7.1 SERVICE CALL CONDITIONS 7-1...............................

7.1.1 SUMMARY 7-1....................................................................

7.1.2 EXPOSURE 7-3...................................................................

7.1.3 SCANNER 7-5.....................................................................

7.1.4 LENS MAGNIFICATION 7-8................................................

7.1.5 OPTICS THERMISTOR 7-10.................................................

7.1.6 CHARGE CORONA UNIT 7-10.............................................

7.1.7 DEVELOPMENT 7-11............................................................

7.1.8 PROCESS CONTROL SENSORS 7-12................................

7.1.9 TRANSFER CURRENT 7-15.................................................

7.1.10 DRUM 7-15..........................................................................

7.1.11 PAPER FEED 7-16..............................................................

7.1.12 DUPLEX 7-19......................................................................

7.1.13 FUSING 7-20.......................................................................

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7.1.14 SYSTEM CONTROL 7-22...................................................

7.1.15 DUAL JOB FEEDER 7-23....................................................

7.1.16 SORTER STAPLER 7-24....................................................

7.1.17 OTHERS 7-28......................................................................

7.2 ELECTRICAL COMPONENT DEFECTS 7-30................

7.2.1 SENSORS 7-30.....................................................................

7.2.2 SWITCHES 7-34....................................................................

7.2.3 FUSES 7-35...........................................................................

POINT TO POINT DIAGRAM & ELCTRICAL

A246/A247/A248/A822 POINT TO POINT DIAGRAM

ELECTRICAL COMPONENT LAYOUT (A246/ A247/ A248 ELECTRICAL COMPONENT LAYOUT (A246/ A247/ A248

SORTER STAPLER (A821)

ELECTRICAL COMPONENT LAYOUT (A821)

Page 9



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. 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. The copier is not attached to the table. Pushing the copier too heard may cause it to drop onto the floor. While moving the copier, push the table.

7. When the main switch is tuned on, the machine will suddenly start turning to perform the developer initialization. Keep hand away from any mechanical and electrical components during this per iod.

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.

CAUTION:

The RAM board on the main control boar d has a li thi u m batt er y which can explode if replaced incorrectly. Replace the RAM board only with an identical one. Th e man u fact urer re co m men ds re pl aci ng the entire RAM board. Do not recharge or burn this battery. Used RAM board must be handled in accordance with local regulations.

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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 photoconductor according to local regulations. (These are non-toxic supplies.)

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

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

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21 September 1998 SPECIFICATION

1. OVERALL MACHINE INFORMATION

1.1 SPECIFICATION

Configuration: Console Copy Process: Dry electrostatic transfer system Toner Supply Control: Fuzzy Control Photoconductor: OPC drum Originals: Sheet/Book Original Size: Maximum A3/11" x 17" Original Alignment: Left rear corner Copy Paper Size: Maximum A3/11" x 17" (Tray & By-pass)

A4/8

Minimum A5/5

A4/8 A6/5

Duplex Copying: Maximum A3/11" x 17"

Minimum A5/5

Copy Paper Weight: Paper tray: 52 ~ 128 g/m2, 14 ~ 34 lb

By-pass feed table: 52 ~ 200 g/m2, 14 ~ 53 lb Duplex copying: 64 ~ 104 g/m2, 17 ~ 24 lb

" x 11" (Tandem LCT)

1/2

" x 8

1/2

" x 11" (Tandem LCT)

1/2

" x 8

1/2

" x 8

1/2

" (Tray)

1/2

" (By-pass)

1/2

" (Sideways)

1/2

Overall

Information

Reproduction Ratios: 4 Enlargement and 5 Reduction + Create Margin

(93%)

A4/A3 Version LT/LDG Version

200%

Enlargement

Full Size 100% 100%

Reduction

141% 122% 115%

82% 75% 71% 65% 50%

200% 155% 129% 121%

85% 77% 74% 65% 50%

1-1

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SPECIFICATION 21 September 1998

Power Source: 115 V, 60 Hz, more than 20 A (for N.A)

220 ~ 240 V, 50 Hz/60 Hz, more than 10 A (for Europe and Asia)

Power Consumption:

- A246 copier -

Copier only Full system*

Warm up 1.20 kVA 1.22 kVA

Stand-by*

Low Power mode*

0.22 kVA 0.24 kVA

0.185 kVA 0.205 kVA

Copying 1.40 kVA 1.40 kVA

Maximum 1.70 kVA 1.75 kVA

Off-mode 0.001 kVA 0.001 kVA

- A247 copier -

Copier only Full system*

Warm up 1.20 kVA 1.22 kVA

Stand-by*

Low Power mode*

0.22 kVA 0.24 kVA

0.21 kVA 0.23 kVA

Copying 1.50 kVA 1.50 kVA

Maximum 1.70 kVA 1.75 kVA

Off-mode 0.001 kVA 0.001 kVA

- A248 copier -

Copier only Full system*

Warm up 1.20 kVA 1.22 kVA

Stand-by*

Low Power mode*

Copying 1.60 kVA 1.60 kVA

Maximum 1.70 kVA 1.75 kVA

Off-mode 0.001 kVA 0.001 kVA

0.22 kVA 0.24 kVA

0.21 kVA 0.23 kVA

*1Full System:



Mainframe with dual job feeder, sorter stapler

and 3,500-sheet large capacity tray

: When the anti-condensation heaters are off.

1-2

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21 September 1998 SPECIFICATION

Noise Emission: Sound Pressure Level:

The measurements are ma de accor di ng to ISO7779

- A246 copier -

Overall

Information

Sound pressure level

Sound power level

- A247 copier -

Sound pressure level

Sound power level

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

Copier only

Stand-by Less than 34 dB (A)

Copying Less than 57 dB (A) (average)

(The measurements are made according to ISO 7779.)

Copier only

Stand-by Less than 48 dB (A)

Copying Less than 71 dB (A) (average)

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

Copier only

Stand-by Less than 34 dB (A)

Copying Less than 59 dB (A) (average)

(The measurements are made according to ISO 7779.)

- A248 copier -

Sound pressure level

Sound power level

Copier only

Stand-by Less than 51 dB (A)

Copying Less than 72 dB (A) (average)

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

Copier only

Stand-by Less than 36 dB (A)

Copying Less than 59 dB (A) (average)

(The measurements are made according to ISO 7779.)

Copier only

Stand-by Less than 54 dB (A)

Copying Less than 73 dB (A) (average)

1-3

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SPECIFICATION 21 September 1998

Dimensions:

Width Depth Height

Copier only Copier with dual job feeder, sorter stapler,

and 3,500-sheet large capacity tray Copier with dual job feeder, sorter stapler with

punch, and 3,500-sheet large capacity tray

690 mm

27.2"

1,659 mm

65.4"

1,659 mm

65.4"

698 mm

27.6"

698 mm

27.6"

698 mm

27.6"

980 mm

38.6"

1,113 mm

43.9"

1,113 mm

43.9"

Weight: Copier only: (Without the optional platen cover

= Approximately 2 kg)

Approximately 175 kg

Zoom: From 50% to 200% in 1% steps Copying Speed:

A246 copier

A247 copier 60 31 38 A248 copier 70 36 44

A4/LT (sideways) A3/DLT B4/LG

51 (A4 others) 50 (A4/in France) 50 (LT)

26 32

Warm-up Time: Less than 5 minutes (A246 copier, 20°C)

Less than 5.5 minutes (A247/A248 copier, 20°C)

First Copy Time: (A4/5

" x 11" sideways

1/2

3.1 seconds (A246 copier)

2.6 seconds (A247/A248 copiers)

from the 1st feed station) Copy Number Input: Number keys, 1 to 999 (count up or count down) Manual Image Density

9 steps

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

second to 999 seconds or no auto reset.

Copy Paper Capacity:



By-pass feed table: approximately 50 sheets



Paper tray: approximately 550 sheets



Tandem LCT tray: approximately 1,550 sheets

Toner Replacement: 1,160 g/cartridge

1-4

Page 15

21 September 1998 SPECIFICATION

Optional Equipment:



Platen cover (A528-04)



Dual job feeder (A610)



20 bin sorter stapler (Floor type) (A821-17:

Ricoh, -22: NRG, -15: Savin/Ges U.S.A. –26: Infotec)



3,500-sheet Large capacity tray (A822)



Receiving tray (A446-05)



Key Counter Bracket D (A509-03)



20 bin sorter Stapler (Floor type) with punch

(A821-57 (3 holes), -67 (2 holes): Ricoh, -62: NRG, -66: Infotec, -55: Savin/Ges U.S.A.)



Guidance ROM KIT Type U (A870)



Editing sheet (spare part)



Original Tray type F (A430-07)



Sorter Adapter type L (A902-19)



20 bin sorter stapler (Hunging type) (A658)

(A246 copier only)

When the 20 bi n sorter stapler (A658) is installed onto A246 copier, sorter adapter type L is required.

Overall

Information

1-5

Page 16

MACHINE CONFIGURATION 21 September 1998

1.2 MACHINE CONFIGURATION

1.2.1 COPIER OVERVIEW

- A246/A247/A248 copiers -



Tandem LCT

(including two 1,550-sheet LCT



Two 550-sheet paper trays



Optional 3,500-sheet large capacity tray

1,550 x 2 550

550

(3,500)

A246V500.WMF

1.2.2 SYSTEM OVERVIEW

Hunging S/S

S/S with Punch

S/S

DJF

Original Tray

Tandem LCT

Hunging Sorter Stapler (A658)

Floor type Sorter Stapler (A821-17, -15, -22, -26) Floor type Sorter Stapler with Punch (A821-57, -67, -55, -62, -66)

1-6

Universal

Fixed

3,500 sheets

LCT

A246V501.WMF

Page 17

21 September 1998 MACHINE CONFI GURATION

MEMO

Overall

Information

1-7

Page 18

COPY PROCESS AROUND THE DURM 21 September 1998

1.3 COPY PROCESS AROUND THE DURM

A246V502.WMF

1. OPC DRUM

The organic photo conductive (OPC) drum (100 mm diameter) has high resistance in the dark and low resistance under light.

2. DRUM CHARGE

In the dark, the charge corona unit gives a uniform negative charge to the OPC drum. The charge remains on the surface of the drum. The amount of negative charge on the drum is proportional to the negative grid bias voltage applied to the grid plate on the charge corona unit.

3. EXPOSURE

An image of the original is reflected to the OPC drum surface via the optics section. 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.

The amount of charge remaining as a latent image on the drum depends on the exposure lamp intensity controlled by the exposure lamp voltage.

4. ERASE

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

1-8

Page 19

21 September 1998 COPY PROCESS AROUND THE DURM

5. DRUM POTENTIAL SENSOR

The drum potential sensor detects the electric potential on the drum to compensate image processing elements.

6. DEVELOPMENT

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

The development bias voltage applied to the development roller shaft controls two things:

1) The threshold level if toner is attracted to the drum or toner remains on the development roller.

2) The amount of toner to be attracted to the drum.

The higher the negative development bias voltage is, the less toner is attracted to the drum surface.

7. PRE-TRANSFER LAMP (PTL)

The PTL illuminates the drum to remove almost all the negative charge from the exposed areas of the drum. This makes image transfer easier.

Overall

Information

8. IMAGE TRANSFER

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

9. PAPER SEPARATION

Paper separates from the OPC drum by the electrical attraction between the paper and the transfer belt. The pick-off pawls help to separate the paper from the drum.

10. CLEANING

The cleaning brush removes toner remaining on the drum after image transfer and the cleaning blade scrapes off all the remaining toner.

11. QUENCHING

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

1-9

Page 20

MECHANICAL COMPONENT LAYOUT 21 September 1998

1.4 MECHANICAL COMPONENT LAYOUT

34567891011

39 38

13 14

15 16 17 18

19 20

34 33 32 31 30 29 41 40 2323

A246V503.WMF

1-10

A246V504.WMF

Page 21

21 September 1998 MECHANICAL COMPONENT LAYOUT

1. 3rd Mirror

2. 2nd Mirror

3. 1st Mirror

4. Exposure Lamp

5. Lens

6. Cleaning Brush

7. Cleaning Blade

8. Quenching Lamp

9. Charge Corona Unit

10. OPC Drum

11. 6th Mirror

12. 4th Mirror

13. 5th Mirror

14. Erase Unit

15. Drum Potential Sensor

22. Registration Rollers

23. Transfer Belt

24. Vertical Transport Rollers

25. Tandem LCT Tray

26. Universal Tray (550-sheet)

27. 550-sheet Tray

28. Toner Collection Bottle

29. Transfer Belt Cleaning Blade

30. Hot Roller

31. Pressure Roller

32. Jogger Fences

33. Duplex Positioning Roller

34. Duplex Pick-up Roller

35. Duplex Feed Roller

36. Separation Belt

Overall

Information

16. Toner Hopper

17. Development Unit

18. Pre-Transfer Lamp

19. Pick-up Roller

20. Feed Roller

21. Separation Roller

37. Junction Gate

38. Exit Rollers

39. Optics Cooling Fan

40. Transfer Belt Cleaning Bias Roller

41. Transfer Belt Bias Roller Blade

1-11

Page 22

DRIVE LAYOUT 21 September 1998

1.5 DRIVE LAYOUT

917















4 5







A246V505.WMF



Main Motor



Scanner Drive Motor



Fusing/Duplex Drive Motor



Paper Feed Motor



Toner Collection Motor



Registration Motor



By-pass Feed Motor



By-pass Feed Clutch



Development Drive Motor

1. To OPC Drum

2. To Scanner Unit

3. To Transfer Belt Unit

4. To Paper Exit Unit

5. To Fusing Unit

6. To Duplex Unit

7. To Cleaning Unit

8. To Paper Feed Units

9. To Toner Hopper

10. To Development Unit

1-12

Page 23

21 September 1998 PAPER PATH

1.6 PAPER PATH

1.6.1 STANDARD COPYING

[D]

[F]

[E]

[C]

[B]

[A]

Overall

Information

[A]

A246V506.WMF

Paper feed begins from the exterior LCT, by-pass feed table or paper feed stations in the paper tray unit. The copy paper then follows one of two paths inside the copier. The path followed depends on which mode the operator has selected. For copy processing, all sheets follow the same paths from the paper feed mechanism [A] through the registration rollers [B], transfer belt [C], and fusing unit [D]. After that, copies are delivered to the sorter bins [E] or proof tray [F], however, 2 sided copies are diverted for further processing.

1-13

Page 24

PAPER PATH 21 September 1998

1.6.2 MULTIPLE 2-SIDE COPYING

a. Front Side

b. Rear Side

[B]

[A]

[D]

[C]

A246V507.WMF

A246V508.WMF

In this mode the junction gate [A] directs sheets exiting the fusing unit to the duplex tray entrance. After that, all sheets follow the path through the duplex entrance rollers [B].

After all front side copying is fed, the sheets on the duplex tray are fed in order from the bottom to the top and follow the path through the duplex feed mechanism and vertical transport rollers [C] to the registration rollers [D]. After that, these sheets follow the same path as standard copying from the registration rollers to the sorter.

1-14

Page 25

21 September 1998 ELECTRICAL COMPONENT DESCRIPTIO N

1.7 ELECTRICAL COMPONENT DESCRIPTION

Refer to the electrical component layout on the reverse side of the point-to-point diagram for the location of the components using the symbols and index numbers.

Symbol Name Function Index No.

Motors

M1 Scanner Drives the 1st and 2nd scanners. 5 M2 3rd Scanner Drives the 3rd scanner. 11 M3 Lens Horizontal Shifts the lens vertical position. 10 M4 Lens Vertical Shifts the lens horizontal position. 19 M5 Main Drives the main unit components. 120 M6 Development Dr ives the development unit. 121

M7 M8

M9 M10 M11 M12 M13 M14 M15

M16 By-pass Feed Drives the by-pass feed rollers. 124 M17 Registration Drives the r eg istr ation rollers. 123

M18 M19

M20 Optics Cooling Fan Removes heat from the optics unit. 21 M21

M22 M23 M24

Toner Bottle Charge Wire

Cleaner Fusing/Duplex Drives the f using unit, the duplex unit,

Toner Collection Toner Recycle Drives the air pump to send recycled Paper Feed Drives all feed and transport rollers in the 1st Lift 2nd Lift Raises the bottom plate in the 2nd paper 3rd Lift Raises and lowers the bottom plat e in the

Rear Fence Moves the paper stack in the left tandem Jogger

Optics Board Cooling Fan

Drum Cooling Fan Cools the drum unit to removes heat Duplex Cooling Fan Exhaust Fan Removes heat from around the fusing

Rotates the toner bottle to supply toner to toner hopper.

Drives the charge wire cleaner to clean the charge wire.

and the exit rollers. Transports the collected toner in the

toner recycle unit for toner recycle. toner to the development unit. paper tray unit.

Raises the bottom plate in the 1st paper tray.

tray. 3rd paper tray.

tray to the right tandem tray. Drives the jogger fences to square the

paper stack in the duplex unit.

Removes heat from around the optics board.

from around the duplex unit. Cools the paper on the duplex tray to

reduce the heat around the drum. unit.

133

30 119 126 129

118 106 114 104

Overall

Information

1-15

Page 26

ELECTRICAL COMPONENT DESCRIPTION 21 Sept ember 1998

Symbol Name Function Index No.

Magnetic Clutches

MC1

Toner Supply

Turns the toner supply roller to supply toner to the development unit.

122

MC2 Toner Recycling Dr ives the toner recycling unit. 125 MC3 1st Feed Starts paper feed from tray 1. 75 MC4 2nd Feed Starts paper feed from tray 2. 79 MC5 3rd Feed Starts paper feed from tray 3. 82 MC6 By-pass Feed Starts paper feed from the by-pass table. 64

Duplex Transport Drives the duplex transport rollers to

MC7

transport the paper to the vertical

transport rollers.

MC8

Duplex Feed Starts paper feed out of the duplex tray

to the duplex transport rollers.

Switches

SW1 Main Provides power to the copier. 117 SW2

SW3 SW4

Front Door Safety Cuts the power line and detects is the

front door is opened or not.

Toner Collection Bottle

2nd Paper Size

Detects if the toner collection bottle is set or not.

Determines what size paper is in the 2nd paper tray.

115 128 100

SW5 3rd Tray Set Detects if the 3rd tray is set or not. 99 SW6

By-pass Table Detects if by-pass feed table is open or

closed.

Solenoids

SOL1 SOL2 SOL3 SOL4 SOL5 SOL6 SOL7 SOL8

SOL9

SOL10

Transfer Belt Positioning

Controls the up-down movement of the transfer belt unit.

1st Pick-up Controls the up-down movement of the

pick-up roller in tray 1.

2nd Pick-up

Controls the up-down movement of the pick-up roller in tray 2.

3rd Pick-up Controls the up-down movement of the

pick-up roller in tray 3.

By-pass Pick-up Contr ols the up-down movement of the

pick-up roller for by-pass feed.

1st Separation Roller

2nd Separation Roller

3rd Separation Roller

Right Tandem Lock

Controls the up-down movement of the separation roller in tray 1.

Controls the up-down movement of the separation roller in tray 2.

Controls the up-down movement of the separation roller in tray 3.

Locks the right tandem tray during transporting the paper from right tray to left tray.

Left Tandem Lock Locks the left tandem tray so that it can

be separated from the right tandem tray.

101

1-16

Page 27

21 September 1998 ELECTRICAL COMPONENT DESCRIPTIO N

Symbol Name Function Index No.

SOL11 SOL12 SOL13 SOL14 SOL15 SOL13

Front Side Fence Rear Side Fence Contr ols the open and close movement Duplex Positioning Controls the up-down movement of the Pressure Arm Guide Plate Opens the guide plate when a paper Junction Gate Moves the junction gate to direct copies

Controls the open and close movement of the front side fence.

of the rear side fence. positioning roller.

Presses the paper on the duplex tray against the duplex feed rollers.

misfeed occurs around this area. to the duplex tray or to the paper exit.

Sensors

S1 S2 S3 S4

Scanner HP Informs the CPU when the 1st and 2nd

scanners are at the home position.

3 rd Scanner HP

Informs the CPU when the 3rd scanner is at the home position.

Lens Vertical HP Informs the CPU when the lens is at the

full-size position.

Lens Horizontal HP Informs the CPU when the lens is at the

horizontal home position.

2 9 7

S5 APS Detects original size. 20 S6

Auto Image Density

Senses the background density of the original.

6 S7 Drum Potential Det ects the drum surface potential. 31 S8

Toner Density Image Density Detects the density of the ID sensor

Detects the amount of toner in the developer.

pattern on the drum.

37 32

S10 Toner Near End Detects the toner end condition. 36

1st Paper Feed Controls the 1st paper feed clutch off/on

S11

timing and the 1st pick-up solenoid off

timing.

2nd Paper Feed Controls the 2nd paper feed clutch off/on

S12

timing and the 2nd pick-up solenoid off

timing.

3rd Paper Feed

S13

Controls the 3rd paper feed clutch off/on timing and the 3rd pick-up solenoid off

timing.

S14 S15 S16 S17

1st Lift Detects when the paper in tray 1 is at the

correct height for paper feed.

2nd Lift

Detects when the paper in tray 2 is at the correct height for paper feed.

3rd Lift Detect s when the paper in tray 3 is at the

correct height for paper feed.

1st Paper End Informs the CPU when tray 1 runs out of

paper.

93 80 85 92

Overall

Information

1-17

Page 28

ELECTRICAL COMPONENT DESCRIPTION 21 Sept ember 1998

Symbol Name Function Index No.

S18 S19 S20 S21 S22 S23

S24

2nd Paper End 3rd Paper End Informs the CPU when tray 3 runs out of By-pass Paper End Informs the CPU that there is no paper in 1st Paper Near End 2nd Paper Near

End 3rd Paper Near End Informs the CPU when the paper in tray

Right Tray Down

Informs the CPU when tray 2 runs out of paper.

paper. the by-pass feed table.

Informs the CPU when the paper in tray 1 is almost finished.

Informs the CPU when the paper in tray 2 is almost finished.

3 is almost finished. Informs the CPU when the bottom plate

is completely lowered, to stop the 1st tray

90 88 65 53 77 86

lift motor.

S25 S26 S27 S28 S29 S30 S31 S32

Right Tray Paper Detects whether there is paper in the

right tandem tray.

Front Side Fence Open

Front Side Fence Close

Rear Side Fence Open

Rear Side Fence Close

Informs the CPU when the front side fence is open.

Informs the CPU when the front side fence is close.

Informs the CPU when the rear side fence is open.

Informs the CPU when the rear side fence is close.

Rear Fence HP Informs the CPU when the tandem tray

rear fence is in the home position.

Rear Fence Return Informs the CPU when the tandem tray

rear fence is in the return position.

Left Tandem Paper Informs the CPU when the left tandem

tray runs out the paper.

50 58 57 48 47 59 51

56 S33 Paper Guide Detect s the misfeeds. 61 S34

Duplex Entrance

Detects the leading edge of the paper to determine duplex feed clutch off timing.

Duplex Transport Detects the leading edge of the paper to

S35

control the jogger motor and the

positioning solenoid on timing.

Duplex Exit

S36

Detects the leading edge of the paper to determine duplex transport clutch on

timing.

S37 Duplex Paper End Detects the paper in the duplex tray. 46 S38

S39

Jogger HP Detects if the duplex jogger fences at the

home position or not.

Vertical Transport

Detects the leading edge of the paper to determine the paper feed timing of next

sheet.

S40

Guide Plate Position

Detects whether the registration guide plate is closed.

1-18

Page 29

21 September 1998 ELECTRICAL COMPONENT DESCRIPTIO N

Symbol Name Function Index No.

S41

Registration

Detects misfeeds and controls the registration roller on-off timing.

70 S42 Fusing Exit Detects misfeeds. 72

S43 Exit Detects misfeeds. 73 S44

S45

S46

S47

Auto Response Toner Overflow Detects when the toner collection bottle Original Length

(LT version only) Platen Cover

Position 1 (Option)

Returns the display from the screen saver.

is full. Detects the original length.

Inform the CPU that the platen cover is in the up or down position (related to

127

APS/ARE function).

S48

Platen Cover Position 2 (Option)

Inform the CPU that the platen cover is in the up or down position to detect if the

original has been removed or not.

PCBs

PCB1 Main Controls all machine functions. 107 PCB2

AC Drive Provides ac power to the fusing lamp and

exposure lamp.

102

PCB3 DC Power Supply Provides dc power. 110 PCB4 Optic Control Controls all optics components. 105

PCB5 PCB6

PCB7

Paper Feed Control Controls all components in the paper

bank.

Operation Panel Control

Left Operation Panel

Controls LEDs and LCD on the operation panel.

Interfaces the LEDs, keys, and the auto response sensor on the left operation

109

panel.

PCB8 PCB9

Right Operation Panel

By-pass Paper Size Inform the CPU what size of the paper is

Interfaces the LEDs and keys on the right operation panel.

in the by-pass feed table.

Overall

Information

Lamps

Exposure Lamp Applies high intensity light to the original

for exposure.

L2 Fusing Lamps Provide heat t o the hot roller. 24 L3

L4 L5

Quenching Neutralizes any charge remaining on the

drum surface after cleaning.

Erase

Discharge the drum outside of the image area.

Pre-transfer Reduce the charge on the drum surface

before transfer.

1-19

Page 30

ELECTRICAL COMPONENT DESCRIPTION 21 Sept ember 1998

Symbol Name Function Index No.

Power Packs

Charge

PP1

Provides high voltage for the charge corona wires and the grid plate. Interfaces the QL, PTL, and charge wire

cleaner motor control signals.

Development Provides hig h volt age for the

PP2

development unit. Interfaces the transfer p.p. and the

108

charge p.p. signals.

Transfer Provides high voltage for the transfer

PP3

belt. Interfaces the transfer belt positioning

solenoid control signal.

Heaters

Optic Anti-condensation

Turns on when the main switch is off to prevent moisture from forming on the

optics.

Transfer Anti-condensation

Turns on when the main switch is off to prevent moisture from forming on the

134

optics.

H3 H4

Upper Tray Turns on when the main switch is off to

keep paper dry in the paper tray.

Lower Tray

Turns on when the main switch is off to keep paper dry in the paper tray.

131 130

Thermistors

TH1

Optic

Monitors the temperature of the optics cavity.

TH2 Fusing Detects the temperature of the hot roller. 25 TH3

Drum Monitors the temperature of the OPC

drum.

Others

CB1 CO1 CO2

LA1

LCD1

Circuit Breaker Provides back-up high current protection

for the electrical components.

Total Counter Keeps track of the total number of copies

made.

Key Counter

Keeps track of the total number of copies made when the key counter is set.

Lightening Arrestor Removes current surges from the ac

input lines.

LCD Displays the operation menus and

messages. NF1 Noise Filter Remove the electrical noise. 112 RA1 Main Power Relay Contro ls main power. 103

TF1

Fusing Thermofuse Opens the fusing lamp circuit if the fusing

unit overheats.

113 132

116

1-20

Page 31

21 September 1998 ELECTRICAL COMPONENT DESCRIPTIO N

Symbol Name Function Index No.

TR1 TS1

Transformer (220 V version only)

Optics Thermoswitch

Makes power for the exposure lamp.

Opens the exposure lamp circuit if the

optics unit overheats.

111

Overall

Information

1-21

Page 32

21 September 1998 PROCESS CONTROL

2. DETAILED SECTION DESCRIPTIONS

2.1 PROCESS CONTROL

2.1.1 OVERVIEW

Ori

inal Scale

Image Density Control (Fuzzy Control)

Latent Image Control

VD Pattern VL Pattern

Latent Image Control

Exposure Control

Charge Control

Drum Thermistor

Lamp Voltage

Grid Voltage

Paper

ADS Pattern

VD Pattern

Erase Lamp

Drum Potential Sensor

Detailed

Descriptions

Pattern

Original Exposure Glass

Toner Supply On Time

Development Bias

TD Sensor

ID Sensor

Image Density Control

(Fuzzy Control)

Toner Supply Control

Main PCB

A246D529.WMF

This model uses two process control methods. One compensates for variation in the drum potential (latent image control) and the other controls the toner concentration and toner supply amount (image density control).

2-1

Page 33

PROCESS CONTROL 21 September 1998

Latent Image Control

Charge

Exposure

Black White

Erase

A246D550.WMF

The figure shows drum potential changes during the copy process.

VO: The drum potential just after charging the drum. VD (Dark Potential): The drum potential just after exposing the black

pattern (VD pattern)

VL (Light Potential): The drum potential just after exposing the white

pattern (VL pattern)

Potential Sensor

Drum

VR (Residual Voltage): The drum potential just after the exposure to the

erase lamp.

After long usage following installation or a PM, drum potential will gradually increase due to the following factors:



Dirty optics or exposure lamp deterioration



A dirty charge corona casing and grid plate



A change in drum sensitivity

In this copier, the drum potential sensor detects the change in drum potential and controls the following items to maintain good copy quality:



The grid-bias voltage



The exposure lamp voltage



The development bias voltage.

A drum thermistor detects the drum temperature and acquires data. The thermistor uses this data to control the above voltages. It is impossible to explain this process simply because it is controlled by methods developed in our laboratories using an artificial neural network.

2-2

Page 34

21 September 1998 PROCESS CONTROL

Image Density Control

The following sensors control image density:



Toner Density sensor (TD sensor)



Image Density sensor (ID sensor)

Data from the TD sensor maintains the toner concentration in the developer at a constant level. However, the image on the OPC drum varies due to the variation in toner chargeability (influenced by the environment), even if the toner concentration is constant. Toner concentration changes to maintain the image density on the OPC drum because of compensation by the ID sensor.

The following items are controlled to maintain a constant copy image density:



Toner supply clutch on time



Toner supply level data (V

) of the TD sensor

REF

Detailed

Descriptions

2-3

Page 35

PROCESS CONTROL 21 September 1998

2.1.2 PROCESS CONTROL DATA INITIAL SETTING

The following flow chart shows the steps performed when turning on the machine while the hot roller temperature is below 100°C. This initializes all the process control settings.

Main SW ON (Fusing Temp. < 100C

Charge wire cleaning (if more than 5 k copies are made since last cleanin

Drum Potential Sensor Calibration

Drum Conditioning Start (Fusing Temp. = 180°C



VSG Adjustment

Transfer belt voltage detection

VR Measurement

VD/VL Correction

)

TD Sensor Detection



ID Sensor Detection/Correction



ADS Adjustment

See Latent Image Control section



e 2-5) for details.

(Pa See Image Density Control section



(Page 2-12) for deteails. See Optics section (Page 2-44) for details.



A246D551.WMF

2-4

Page 36

21 September 1998 PROCESS CONTROL

2.1.3 LATENT IMAGE CONTROL

Drum Potential Sensor Calibration

[A]

Case Sensor

Output

Amp.

Detailed

Descriptions

Drum

[B]

A246D554.WMF

Main PCB

A246D552.WMF

The potential sensor [A] for the drum is just above the development unit. The sensor has a detector that detects the strength of the electric field from the electric potential on the drum. The output of the sensor depends on the strength of the electric field.

Since environmental conditions affect sensor output, such as temperature and humidity, the sensor output is calibrated during process control data initialization.

The High Voltage Control PCB [B] has two relay contacts. Usually RA602 grounds the drum. However, during the initial setting, the main PCB turns RA601 on and RA602 off and applies the voltage to the drum shaft.

By measuring the output of the drum potential sensor when –100 V and –800 V are applied to the drum, the sensor output is calibrated automatically. (The machine recognizes the relationship between actual drum potential and the potential sensor output.)

2-5

Page 37

PROCESS CONTROL 21 September 1998

Drum Conditioning

When the fusing temperature reaches 180°C, the machine starts the drum conditioning process. In this mode, the main motor, main charge corona, erase lamp and development bias are activated for about 30 seconds and drum sensitivity and residual voltage (VR) are stabilized, as in continuous copy runs.

VSG Adjustment

During drum conditioning, the ID sensor checks the reflectivity of the bare drum and calibrates the output of the ID sensor to 4  0.2 V.

VR Measurement

[-V]

New Drum Used Drum

Drum Potential

Original Density

LightDark

A246D561.WMF

The above figure shows the relationship between the drum potential and the original density. This relationship must persist to maintain copy quality.

Since this relationship tends to change to the one represented by the dotted line by various factors, some compensation is necessary.

Increasing the exposure lamp voltage cannot compensate for the residual voltage (VR). Therefore, other means are required to compensate for VR change.

The main control board checks the drum potential just after the erase lamp exposure with the drum potential sensor, after drum conditioning. This measured drum potential is in fact VR. This VR is the standard for the VD and VL corrections.

NOTE:

In the figure above, the residual voltage (VR) for the new drum is 0 V. Actually, there is some residual voltage even on a new drum.

2-6

Page 38

21 September 1998 PROCESS CONTROL

VD Correction

Exposure

[-V]

Pattern

Glass

A246D566.WMF

Drum Potential

-770

New Drum

Original Density

VD Compensated

After many copies

LightDark

A246D568.WMF

The drum potential just after the black pattern (VD Pattern) is exposed (VD: Dark Potential) tends to lower during drum life due to a decrease in the capacity of the drum to carry a charge.

Detailed

Descriptions

To check the actual VD, the first scanner moves to the home position, exposing the VD pattern (Black) stuck on the bottom side of the exposure glass bracket on the drum.

The main control board measures VD using the drum potential sensor and adjusts it to a target value by adjusting the grid-bias voltage (V

GRID

On the other hand, the drum residual voltage (VR) changes to compensate for the target VD voltage in the following manner:

Target VD Value: VD = VR + (–770) The adjusted grid-bias voltage (V

) remains in memory until the next process

GRID

control data initialization.

2-7

Page 39

PROCESS CONTROL 21 September 1998

VL Correction

[-V]

Drum Potential

-770

-140

Exposure

Glass

A246D566.WMF

VL Pattern

Original Density

Only VD Compensated

VD and VL Compensated

LightDark

A246D594.WMF

New Drum

Dirty optics and/or exposure lamp deterioration decreases the intensity of the light that reaches the drum. In addition to this, the drum sensitivity also changes during the life of the drum. These factors change the drum potential just after white pattern exposure (VL: Light Potential).

To check the actual VL, the lens moves to the VL pattern check position. This exposes the VL pattern (White) stuck underneath the original scale on the drum.

The main control board measures VL using the drum potential sensor and adjusts it to a target value by adjusting the exposure lamp voltage (V

LAMP

The residual voltage (VR) change also affects VL, to compensate for the target voltage of VL in the following manner:

Target VL Value: VL = VR + (–140)

The adjusted exposure lamp voltage (V

) is stored in memory until the next

LAMP

initial setting of the process control data.

2-8

Page 40

21 September 1998 PROCESS CONTROL

VR Correction

[-V]

Drum Potential

-770

-140

Development Bias (VBB)

VD and VL Compensated

New Drum

Detailed

Descriptions

Dark Light

Original Density

A246D602.WMF

The potential sensor monitors potentials (VR, VD, and VL). During the check cycle, the VD and VL patterns are exposed. The potential sensor checks the drum potential in the area exposed by each pattern.

Compare the curve of the VD and VL compensated drum potential with the curve of the new drum, they are parallel but the compensated potential is still higher (VR) than the new drum potential. To prevent dirty backgrounds due to increased residual potential, development bias (VBB) is applied as follows:

VBB = VR + (–220)

2-9

Page 41

PROCESS CONTROL 21 September 1998

Initial Setting Sequence

The following graph shows the sequence of events during the initial setting of the process control data.

For the purpose of ADS sensor correction

Exposure Lamp

Potential Sensor Output

800

100

1. Potential sensor

2. VR’, VD’, VL’

Latent Image Control

potential

New V

3. V

New V

D, VL

correction

4. ID sensor pattern potential

A246D604.WMF

1. Potential sensor calibration Measuring the output of the drum potential sensor when applying –100 V and – 800 V to the drum, automatically calibrates the sensor output (V

100

and V

See page 2-5 for details.

800

2. VR, VD, VL potential detection After about 30 seconds of drum conditioning, VD and VL Patterns are developed by using the previous grid-bias voltage (V lamp voltage (V

The machine calculates the new V

) data to detect the VR, VD, VL data.

LAMP

and V

GRID

data using the detected VR,

LAMP

) data and exposure

GRID

VD, and VL data.

2-10

Page 42

21 September 1998 PROCESS CONTROL

3. VD and VL corrections Using the calculated V

GRID

and V

data, the VR, VD, and VL patterns are

LAMP

redeveloped thereby determining the new VR, VD, and VL data. If both VD and VL data are within specifications, the new VD, VL, and VR values determine the new V

GRID

, V

and development bias (VBB).

LAMP

Specifications:

VD = –770 + VR  20 V VL = –140 + VR  20 V

If VD is outside specifications, V measured and VD is detected again. The same is done for VL and V

is shifted one step. Then the VD pattern is re-

GRID

LAMP

. The above process continues until both VD and VL fall within specifications. The graph on the previous page shows an example of when only VL was outside the specifications at the first VL detection. It came within specifications after one V correction by changing V

0.5 V/step, and V

LAMP

by 20 V/step.

GRID

Detailed

Descriptions

The machine stops VD/VL correction and uses the previous V

GRID

and V

LAMP

values during copying in the following instances:



If V

100

or V

at the calibration of the drum potential sensor is outside

800

specifications.



If VD or VL does not fall within specifications after shifting V

GRID

or V

LAMP

their maximum and/or minimum levels.

In this case, the machine indicates nothing, but the SC counter increments. Related SC codes (see troubleshooting section for details):

Code Condition

361 Incomplete drum potential sensor calibration 364 Abnormal VD detection 365 Abnormal VL detection 366 VR abnormal

Utilizing VR in the following manner can also determine the development bias:

VBB = VR + (–220)

4. The ID sensor pattern for potential detection

This determines the ID Sensor Bias Voltage. The development control section explains this subject in more detail (see page 2-16).

2-11

Page 43

PROCESS CONTROL 21 September 1998

2.1.4 IMAGE DENSITY CONTROL

Toner Density Sensor

OUT

A: V B: V C: V

(Gain data) is high.

OUT

is within the specification.

OUT

(Gain data) is

low

OUT IN X

V=V

= 12 x

Main PCB

AGC

Gain

256

Gain

256

OUT

(12 V)

GND

Sensor Output

TD Sensor

A246D606.WMF

A246D531.WMF

Developer consists of carrier particles (iron) and toner particles (resin and carbon). Inside the development unit, developer passes through a magnetic field created by coils inside the toner density sensor. When the toner concentration changes, the voltage output by the sensor changes accordingly.

When installing new developer with the standard toner concentration (2.0% by weight, 20 g of toner in 1,000 g of developer), the initial setting for the developer must be performed by using an SP mode (SP1-2-1).

During this setting, the output voltage (V

) from the auto gain control circuit

OUT

(AGC) on the main control board PCB varies to change the output voltage from the toner density (TD) sensor. Changing the gain data does this:

V= V x

OUT IN

Gain Data

256



12 x

Gain Data

256

If the data is large, V results in the sensor sensitivity illustrated by curve A. If the data is small, V

and the sensor output voltage also become large. This

OUT

becomes small, and the sensor output voltage becomes small. As a result, the sensor sensitivity shifts as illustrated by curve C.

2-12

Page 44

21 September 1998 PROCESS CONTROL

By selecting the proper gain data, the sensor output is set within the targeted control level (V

REF

, V

= 2.5  0.1 V). Now, curve B shows the sensor

REF

characteristic and the TD sensor initial setting is complete. The selected gain data is stored in memory, and V

from the auto-gain control

OUT

circuit stays constant during the detection cycle for the toner sensor.

Toner density detection in the developer occurs once in every copy cycle. The sensor output voltage (VTD) during the detection cycle is compared with the toner supply level voltage (V

REF

Detailed

Descriptions

2-13

A246D609.WMF

Page 45

PROCESS CONTROL 21 September 1998

To stabilize toner concentration, the toner supply (toner supply clutch ON period) is controlled by using V

and VTD data.

REF

The toner supply is calculated after each copy. The following factors determine the remaining toner supply:

 

V V

– V

REF REF

– VTD’(VTD’ = VTD of the previous copy cycle)

A246D512.WMF

By referring to these factors, the machine recognizes the difference between the current and target toner concentration. The machine also understands how much the toner concentration changed and can predict how much the toner supply amount will probably change. Precision changes in the toner supply maintain the toner concentration (image density). Since updating the toner supply clutch ON period is under fuzzy control, the relation among VTD, VTD’, V

cannot be expressed by a simple algebraic

REF

formula.

Correction>

REF

The image on the OPC drum changes du e to the variation in toner chargeability (influenced by the environment) even if the toner concentration is constant. The image density sensor (ID sensor) directly checks the image on the OPC drum and shifts V

data (under fuzzy control) to keep the image on the OPC drum

REF

constant, as explained in the next section.

NOTE:

1) The toner end sensor detects the toner end condition (see the development section for details).

2) The toner supply clutch turns on at intervals between each copy process, while image development is not occurring.

2-14

Page 46

21 September 1998 PROCESS CONTROL

Image Density Sensor Detection

[B]

[C]

Drum

[A]

Bias

A246D514.WMF

A246D513.WMF

The ID sensor [A] checks VSG and VSP. The ID sensor is located underneath the drum cleaning section. There is no ID sensor pattern in the optics; however, the charge corona unit [B] and the erase lamp [C] make a pattern image on the OPC drum.

Detailed

Descriptions

VSG is the ID sensor output when checking the erased drum surface. VSP is the ID sensor output when checking the ID sensor pattern image.

To compensate for any variation in light intensity from the sensor LED, the reflectivity of both the erased drum surface and the pattern on the drum are checked.

VSP Detection

V Detection

1st Series of Copies (8 copies)

2nd Series of Copies (5 copies)

V Detection

VSP Detection

V Detection

3rd Series of copies (17 copies)

Detection

V Detection

A246D515.WMF

VSG is detected every time the machine starts copying. During VSG detection, the development sleeve rollers do not rotate and development bias is not applied. If 10 or more copies are made, the copier will re-detect VSP. Since the transfer belt must be released when checking VSP, the machine cannot check the VSP during continuous copying.

2-15

Page 47

PROCESS CONTROL 21 September 1998



Potential

Sensor Detection



ID Sensor

Bias Level

4.0 V



ID Sensor

Output

–800



IDB

= VP + 300 (V)



–300

A246D516.WMF



A246D517.WMF

While developing the ID sensor pattern, ID sensor bias is applied. ID sensor bias is determined during process control data initialization as follows:

Apply charge while the grid voltage is –800 V to create the ID sensor pattern. Check the drum potential (VP) of the latent image created by the charge with –800

V grid. Adjust the ID sensor bias (V

= VP – (–300) (V)

IDB

) so that it satisfies the following formula:

IDB

= VP + 300 (V)

Change the bias to the calculated V

and detect VSP. The VSG value detected

IDB

during its adjustment sequence during process control data initialization and the VSP determine the V

data. The V

REF

does not change until the next initial

IDB

setting for the process control data.

After the series of copies is completed, when 10 or more copies were made, V is updated by referring to the previous V

Correction Timing>

REF

’), VSG, VSP and the current TD

REF

sensor output (VTD). Since this V

’, VSG, VSP and VTD cannot be expressed in a simple algebraic for mula.

REF

The V

is not only updated in the above case, but also during the initial setting

REF

data updating is under fuzzy control, the relationship among V

REF

for the developer and during process control data initialization.

2-16

REF

Page 48

21 September 1998 PROCESS CONTROL

Sensor Abnormal Conditions

a) ID sensor (VSG, VSP) abnormal

Whenever V data and the TD sensor output controls the toner concentration.

Normal detection of VSG and VSP occurs, as usual, during abnormal conditions. If output returns to normal levels (VSG  2.5 V, VSP  2.5 V), the CPU returns the toner concentration control to normal mode.

b) TD sensor (V

Whenever V to the fixed supply mode. In this condition, the CPU never stops the toner supply. The fixed toner supply can be changed in four steps (4%, 7%, 11%, and 14%) by using an SP mode. The default fixed toner supply is 4%.

Detection of VTD still occurs, as usual, during abnormal conditions. If its output returns to a normal level, the CPU returns the toner concentration control to normal mode.

falls under 2.5 V or VSP rises over 2.5 V, the CPU fixes the V

) abnormal

rises over 4.0 V or falls under 0.5 V, the CPU shifts the toner supply

REF

Detailed

Descriptions

c) Drum Potential Sensor abnormal

The CPU shifts the toner supply to fixed supply mode, when the TD sensor (VTD) detects an abnormal condition, in the following cases:



rises over 0.7 V or falls under 0.1 V

100

rises over 4.2 V or falls under 2.7 V

800

Related SC codes. (See troubleshooting section of details.):

Code Condition

351 352 Incomplete TD Sensor Initial Setting 353 354 355 356 358 361 Incomplete Drum Potential Sensor Calibration

Abnormal V

Abnormal V Abnormal V Abnormal V Abnormal V Abnormal V

Detection (VSG  4.2 V)

Detection (VSP  2.5 V)

Detection (VSG  2.5 V)

Detection (VTD  4.7 V)

Detection (VTD  0.5 V)

TD SP/VSG

Detection (VSP/VSG  0.025 V)

2-17

Page 49

DRUM UNIT 21 September 1998

2.2 DRUM UNIT

2.2.1 OVERVIEW

11 10

1514

7, 8 62

A246D518.WMF

The drum unit consists of the components as shown in the above illustration. This model uses an organic photoconductor drum (diameter: 100 mm).

1. OPC Drum

2. Paper Guide Spurs (60/70 cpm only)

3. Erase Lamp

4. Drum Potential Sensor

5. Pre-transfer Lamp

6. Pick-off Pawl

7. Image Density Sensor

8. Drum Thermistor

9. Cleaning Brush

10. Toner Collection Coil

11. Cleaning Blade

12. Ozone Filter

13. Cleaning Filter

14. Charge Power Pack

15. Quenching Lamp

16. Main Charge Corona Unit

2-18

Page 50

21 September 1998 DRUM UNIT

2.2.2 OPC DRUM CHARACTERISTICS

An OPC has the following characteristics:

1) Accepts a high negative electrical charge in the dark. (The electrical resistance of a photoconductor is higher with the absence of light.)

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

3) Dissipates an amount of charge in direct proportion to the intensity of the light. That is, the stronger the light focused on the photoconductor surface is, the smaller the voltage remaining on the OPC.

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

5) Less sensitive to changes in rest time (light fatigue). This makes it unnecessary to compensate for the development bias voltage resulting from variations in the rest time.

Detailed

Descriptions

2-19

Page 51

DRUM UNIT 21 September 1998

2.2.3 DRUM CHARGE

Overview

[A]

A246D519.WMF

This copier uses a double corona wire scorotron system for the drum charge. Two corona wires are required to give sufficient negative charge on the drum surface because of a rather high drum speed (50/51 cpm machine: 330 mm/seconds, 60 and 70 cpm machines: 430 mm/seconds.). The stainless steel grid plate makes the corona charge uniform and controls the amount of negative charge on the drum surface by applying negative grid-bias voltage.

The charge power pack [A] supplies constant current to the corona wires (–1,200



A). Bias voltage supplied to the grid plate is automatically controlled to maintain proper image density even if the OPC drum potential changes due to a dirty grid plate or the charge corona casing.

2-20

Page 52

21 September 1998 DRUM UNIT

Air Flow Around the Drum

[A]

[C]

[E]

[D]

[B]

A246D520.WMF

The exhaust fan [A] located above the fusing unit provides an airflow to the charge corona unit to prevent uneven build-up of negative ions that can cause an uneven charge on the drum surface as shown.

An ozone filter [B] absorbs the ozone (O3) around the drum. The exhaust fan rotates slowly during stand-by and rotates quickly during copying

to keep the temperature inside the machine constant.

Detailed

Descriptions

There is another fan (the drum-cooling fan [C]), which is located on the right rear side of the machine (front view). The drum-cooling fan cools the drum unit to remove the heat from the duplex tray. The drum has 12 holes in each drum flange [D]. Air flows into the drum, through the holes in the drum flange. To prevent foreign matter from entering the inside of the copier, there is a dust protection filter in the entrance [E] of the duct.

2-21

Page 53

DRUM UNIT 21 September 1998

Charge Wire Cleaning Mechanism

[A]

[C]

[A]

[C]

[B]

A246D521.WMF

The flow of air around the charge corona wire may deposit toner particles on the corona wires. These particles may interfere with charging and cause low-density bands on copies.

The wire cleaner pads [A] automatically clean the wires to prevent such a problem. A DC motor [B] drives the wire cleaner. Normally the wire cleaner [C] is in the front-

end position (home position). After 5,000 copies and when the fusing temperature is less than 100°C after the main switch is turned on, the wire cleaner motor brings the wire cleaner to the rear end and then back to the home position.

When the wire cleaner moves from the rear to the home position (black arrow in the illustration), the wire cleaner pads clean the wires.

There are no home-position and return-position sensors. The CPU monitors the input voltage (5 V). When the wire cleaner reaches the end, it is stopped and the motor locks. At this time, input voltage slightly decreases (to about 4 V) and the CPU determines when to reverse the motor.

2-22

Page 54

21 September 1998 DRUM UNIT

2.2.4 ERASE

Overview

Detailed

Descriptions

A246D522.WMF

LE: Lead edge erase margin 3.5  2.5 mm SE: Side erase margin total of both sides 3 mm or less LO: Original width LC: Charged width of drum EL: Lead edge erase ES: Side erase

The erase lamp unit consists of a line of 123 LEDs extending across the full width of the drum, the width of each being about 2.5 mm. In editing mode, the customer determines the active LEDs.

2-23

Page 55

DRUM UNIT 21 September 1998

Lead Edge and Trail Edge Erase

The entire line of LEDs turns on when the main motor turns on. They stay on until the erase margin slightly overlaps the leading edge of the original image on the drum (leading edge erase margin). It prevents the shadow of the original leading edge from appearing on the copy paper. This lead erase margin is also necessary for the leading edge of the copy paper to separate from the hot roller. An SP mode can adjust the width of the leading edge erase margin (SP1-2-4).

When the scanner reaches the return position, the charge corona, the grid bias, and the exposure lamp turn off. However, the charged area on the drum surface is a little longer than the original length in order to capture the entire latent image of the original. The entire line of LEDs turns on when the trail edge of the latent image passes under the erase lamp unit. This prevents developing unnecessary parts of the drum surface; thereby reducing toner consumption and drum cleaning load. The LEDs remain on, erasing the leading edge of the latent image in the next copy cycle. After the final copy, the erase lamps turn off at the same time as the main motor.

Side Erase

Based on the combination of copy paper size and the reproduction ratio data, the LEDs turn on in blocks. This prevents the shadow of the original side edge and unexposed front and rear sides of the drum surface in reduction mode from being developed. This reduces toner consumption and drum cleaning load.

In the DJF mode, the horizontal original standard position on the exposure glass is 5 mm away from the rear scale. On the other hand, the horizontal original standard position on the exposure glass in the platen cover mode is the rear scale edge. One more LED at the front side turns on to erase the shadow made by the edge of the rear scale in platen cover mode. This is in addition to the LEDs that are on in DJF mode.

2-24

Page 56

21 September 1998 DRUM UNIT

2.2.5 CLEANING

Overview

[A]

4 mm

[C]

A246D523.WMF

[B]

Detailed

Descriptions

[D]

A246D524.WMF

This copier uses the counter blade system for drum cleaning. The blade [A] is angled against the drum rotation. This counter blade system has the following advantages:



Causes less wear on the cleaning blade edge.



Has a high cleaning efficiency.

Due to the high efficiency of this cleaning system, this copier does not use the precleaning corona and cleaning bias.

The cleaning brush [B] supports the cleaning blade. The brush collects toner from the drum surface and the cleaning blade scrapes the toner off the brush. Toner on the cleaning brush is scraped off by the mylar [C] and falls to the toner collection coil [D]. The toner collection coil transports the toner to the toner recycle unit.

To remove the accumulated toner at the edge of the cleaning blade, the drum reverses about 4 mm at the end of every copy job. The cleaning brush removes the accumulated toner by this action.

2-25

Page 57

DRUM UNIT 21 September 1998

Drive Mechanism

[C]

[A]

[E]

[B]

[E]

[D]

A246D525.WMF

The timing belt [A] and the cleaning unit coupling [B] transmit drive from the drum motor to the cleaning unit drive gear. The cleaning unit drive gear [C] then transmits the drive to the front through the cleaning brush [D]. The gear at the front drives the toner collection coil gear [E].

2-26

Page 58

21 September 1998 DRUM UNIT

Toner Collection Mechanism

[C]

[A]

[B]

A246D527.WMF

The toner collection tube [A] transports toner collected by the cleaning unit to the toner recycle unit.

Drive belts [C] from the main motor drive the toner transport coil [B].

Detailed

Descriptions

2-27

Page 59

DRUM UNIT 21 September 1998

Cleaning Blade Pressure Mechanism and Side-to Side Movement

[C]

[A]

[D]

[B]

A246D526.WMF

The spring [A] always pushes the cleaning blade against the drum. Pushing up the release lever [B] manually releases the cleaning blade pressure. To prevent cleaning blade deformation during transportation, the release lever must be locked in the pressure release (upper) position.

The pin [C] at the rear end of the cleaning blade holder touches the cam gear [D], which moves the blade from side to side. This movement helps to disperse accumulated toner, preventing early wear of the blade edge.

2-28

Page 60

21 September 1998 DRUM UNIT

Pick-off Mechanism

[A]

Detailed

Descriptions

[B]

A246D528.WMF

The pick-off pawls are always in contact with the drum surface because of weak spring pressure. They move from side to side during the copy cycle to prevent drum wear at any particular location. A shaft [A] and a cam [B] create this movement.

2-29

Page 61

DRUM UNIT 21 September 1998

2.2.6 QUENCHING

[A]

A246D530.WMF

In preparation for the next copy cycle, light from the quenching lamp [A] neutralizes any charge remaining on the drum.

The quenching lamp consists of a line of 16 LEDs extending across the full width of the drum.

2-30

Page 62

21 September 1998 DRUM CLEANING AND TONER-RECYCLING

2.3 DRUM CLEANING AND TONER-RECYCLING

2.3.1 TONER TRANSPORT

[A]

[E]

[B]

[F]

[D]

[C]

A246D500.WMF

The toner transport tube transports the toner collected by the drum cleaning [A] and transfer belt [B] units to the toner-recycling unit [C]. The toner transport coil [D] transports the toner. The main motor [E], using timing belts, pulleys, and gears, drives the transport coil. To ensure good toner flow, a fin [F] breaks up the toner that drops from the tube of the drum-cleaning unit.

Detailed

Descriptions

2-31

Page 63

DRUM CLEANING AND TONER-RECYCLING 21 September 1998

2.3.2 FILTERING

[D]

[A]

A246D501.WMF

[D]

[B]

[D]

[B]

[C]

A246D502.WMF

[D]

[E]

A246D503.WMF

A246D504.WMF

The toner collected by the toner transport coil is delivered to the filtering unit [A]. The filtering unit consists of a mesh filter [B] and agitation bar [C]. The re-usable toner passes through the holes in the mesh filter. The agitation bar in the mesh filter prevents the holes in the mesh filter from being blocked. When the coil rotates, the ball [D] stays in t he groove in the toner exit coil, and prevents the toner from blocking the holes in the mesh filter.

The unusable material (blocked toner and paper dust) does not pass though the holes in the mesh filter. It exits from the mesh filter and drops into the opening [E], which leads to the toner collection bottle.

2-32

Page 64

21 September 1998 DRUM CLEANING AND TONER-RECYCLING

2.3.3 PUMP MECHANISM

[A]

[F]

[B]

[E]

A246D505.WMF

[B]

[D]

[C]

Detailed

Descriptions

[D]

[C]

[D]

[C]

A246D506.WMF

The screw in the toner-recycling unit delivers the re-usable toner to the screwpump unit [B] when the toner-recycling clutch [A] is activated. The screw-pump consists of a rotor [C] and stator [D]. The rotor turns inside the stator, and the screw-pump transports the toner as shown. The toner recycle motor [E] pushes air into the screw-pump, blowing the toner from the screw-pump into the development unit ([E] on the next page) through the toner-recycling tube [F]. The toner hopper has two air pressure release filters ([F] on the next page) because of the amount of air sent to the toner hopper. When the toner supply clutch remains on for 9.3 seconds or the copying time reaches 60 seconds, whichever comes first, the toner-recycling clut ch turns on for 2 seconds. The air pump motor turns on for 6 seconds at the same time as the toner-recycling clutch.

2-33

Page 65

DRUM CLEANING AND TONER-RECYCLING 21 September 1998

2.3.4 DRIVE MECHANISM

[F]

[E]

[A]

[B]

[D]

[C]

A246D507.WMF

The toner-collection motor [B] drives the exit coil [A] for the toner using gears. The toner-recycling clutch [C] and gears drive the pump-unit. The toner recycle motor [D] supplies air. When the tone r-collection motor locks, the LCD displays an SC345 (tonercollection motor abnormal) message. If the toner recycle motor disconnects for more than one second, the LCD displays an SC346 (toner recycle motor disconnected) error message.

2-34

Page 66

21 September 1998 DRUM CLEANING AND TONER-RECYCLING

2.3.5 TONER COLLECTION BOTTLE

[A]

[B]

Detailed

Descriptions

A246D508.WMF

The set switch [A] for the toner collection bottle detects whether it is set properly. The operation panel indicates when the bottle is not set correctly. The toner overflow sensor [B] detects when the toner collection bottle becomes full. In this condition, the copy job can end, or make up to 100 continuous copies. Then copying is disabled and the LCD displays the service call “full toner collection bottle”. De-actuating and then actuating the set switch for the toner collection bottle can clear this condition.

2-35

Page 67

OPTICS 21 September 1998

2.4 OPTICS

2.4.1 OVERVIEW

[A] [B] [C]

[E]

[D]

A246D532.WMF

The optics unit reflects an image of the original from the exposure glass onto the OPC drum. This forms a latent electrical image of the original.

This model utilizes a halogen lamp (85 V 200 W: A246 copier, 225 W: others) for the exposure lamp [A]. The lamp surface is frosted to ensure even exposure.

Six mirrors are used to make the optics unit smaller and obtain a wide reproduction range ratio (50 ~ 200%).

Two stepper motors drive the lens [B] (1) vertically (parallel to the paper feed direction) and (2) horizontally.

A stepper motor changes the position of the third scanner unit [C] (4th and 5

mirrors) to correct the focal length changes during reduction and enlargement modes.

The toner shielding filter [D] is green (a green filter partly absorbs red light) to improve duplication for red originals.

The optic anti-condensation heater [E] (located on the optic base plate) turns on while the main switch is off to prevent moisture from forming on the optical equipment.

2-36

Page 68

21 September 1998 OPTICS

2.4.2 SCANNER DRIVE

[A]

[B]

[D]

[C]

[E]

A246D533.WMF

The scanner drive motor [A] is a DC servomotor. The scanner drive speed is 330 mm/second (50/51-CPM version) or 430 mm/second (other versions) during scanning. When the scanner goes back, scanner drive speed is 1,950 mm/second (50/51, 60-CPM versions). For the 70-CPM version, the scanner drive speed changes in relation to the paper size.

Detailed

Descriptions

Paper size

DLT  X  B4 B4  X  A4 lengthwise A4 lengthwise  X  LT sideways LT sideways  X  B5 sideways B5 sideways  X  A5 sideways A5 sideways  X

A248 copiers scanner return speed

(mm/seconds)

1,580 1,650 2,000 2,000 1,900 1,550

X: Paper size

The scanner drive motor drives the first [B] and second scanners [C] using two scanner drive wires via the timing belt [D] and the scanner drive shaft [E]. The second scanner speed is half the speed of the first scanner.

2-37

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OPTICS 21 September 1998

(

)

2.4.3 VERTICAL LENS DRIVE

- EU and Asia - - U.S.A. -

[B]

[A]

[B]

[A]

A246D614.WMF

A246D534.WMF

Home position

(100%)

Enlarge Reduce

(Enlarge  home position)

(Reduce  home position)

(Enlarge  Enlarge) (Reduce  Reduce)

Enlarge  Reduce

(Reduce  Enlarge)

30 30 30 30 steps

A246D535.WMF

The vertical drive motor [A] for the lens changes its vertical position in accordance with the selected reproduction ratio.

A stepper motor (approx. 0.095 mm/step) shifts the lens using a drive belt. The maximum vertical-shift distance for the lens is 290 mm (from its position at 50% to 200%). The vertical HP sensor [B] detects the vertical position of the lens in fullsize mode. The optics control PCB keeps track of its position by the number of pulses sent to the vertical drive motor.

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21 September 1998 OPTICS

2.4.4 HORIZONTAL LENS DRIVE

- EU and Asia - - U.S.A.-

Detailed

Descriptions

[A]

A246D615.WMF

Enlarge

Home position

Reduce

[A]

A246D536.WMF

40 steps

A246D537.WMF

The original horizontal position on the exposure glass varies depending on the mode (such as platen or DJF modes) to make it easier to handle the original. However, the central paper feed is the standard position for paper.

Therefore, the horizontal position of the lens must change according to the paper size, reproduction ratio and original feed and edit modes (centering, margin adjust, etc.).

A stepper motor (approx. 0.07 mm/step) moves the lens using the drive belt. The horizontal HP sensor [A] for the lens detects its horizontal position for A4/LT sideways original, in full-size and platen modes.

The other positions are determined by counting the number of motor drive pulses. Since this model has a horizontal lens drive mechanism, side-to-side registration

adjustment for each feed station can be done easily using an SP mode (SP1-1-1 Side to Side Registration Adj.).

2-39

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OPTICS 21 September 1998

2.4.5 HORIZONTAL LENS POSITIONING

For Original Position

[A]

Copy Paper

Center

Horizontal

Lens Position

[C]

[B]

A246D538.WMF

A246D539.WMF

There are two standard positions for the original in platen and DJF modes. In platen mode, the original aligns with both the rear [A] and the left [B] original

alignment scales (rear left corner [C] is the standard position). In DJF mode, the original position is 5 mm in front of the platen-mode original

position to maintain the original transport path (5 mm from the rear scale). The above figure shows the horizontal lens positions in each mode when using one

paper size.

For Paper Size

Original Rear Edge

Lens Position

Copy Paper

Horizontal

A246D540.WMF

To maintain high paper feed performance, the central paper feed is the standard position for paper. Consequently, the horizontal lens position changes according to the paper size.

The figure shows the lens horizontal position for each paper size in full-size mode.

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21 September 1998 OPTICS

For Reproduction Ratio

50%100%200%

50%

100%200%

3rd Scanner Position

Copy Paper

A246D541.WMF

When the reproduction ratio changes, so does the vertical position of the lens. At the same time, the total focal length must shift to adjust the focus of the image. To change the focal length, the vertical position of the 3rd scanner adjusts to a maximum distance of 50 mm (from its position at 100% to the position at 50 or 200%).

Detailed

Descriptions

The figure shows the lens horizontal position at 50, 100 and 200%.

2-41

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OPTICS 21 September 1998

(

)

2.4.6 3RD SCANNER DRIVE

[B]

[A]

A246D542.WMF

(Initialize)

(Reduce/Enlarge

(Reduce/Enlarge  Reduce/Enlarge)

Reduce/Enlarge  Reduce/Enlarge

(Reduce/Enlarge  Enlarge/Reduce)

40 steps40 steps

A246D543.WMF



For the focus to compensate for reproduction and lens position changes, the 3rd scanner (4th and 5th mirrors) position is changed.

The 3rd scanner drive uses a stepper motor [A] (approx. 0.095 mm/step). The 3rd scanner HP sensor [B] detects the unit position for ful l- si z e mode. The

optics control PCB keeps track of the unit position from the number of motor drive pulses.

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21 September 1998 OPTICS

2.4.7 OPTICS CONTROL CIRCUIT

Sensors

Encoder

Data

Main Control Board

Bus

Main

CPU

Exposure Lamp

Optics Control Board

Optics Control CPU

AC Drive Board

Optic Thermistor

A246D544.WMF

Scanner Drive

Horizontal Lens Drive

Vertical Lens Drive

Scanner Drive

Optic Cooling Fan

The optics control board communicates with the main board through a data bus. It monitors all the sensor signals, encoder and thermistor output and controls all the motors for optics.

Detailed

Descriptions

At the programmed time, the main CPU sends a scanner start signal to the optics control CPU.

The CPU generates a pulse-width modulation (PWM) signal. The PWM signal goes to a driver circuit, which sends drive pulses to the scanner drive motor.

An encoder in the scanner drive motor generates pulse signals. A speed/direction control circuit monitors the scanner speed and the direction of the signals, and uses this data to regulate the motor speed.

The HP sensor monitors the position of the scanner. After turning on the copier, the main CPU confirms the scanner position by moving the scanner out of the home position and back again. This data is sent to the optics control CPU.

2-43

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OPTICS 21 September 1998

2.4.8 AUTOMATIC IMAGE DENSITY CONTROL SYSTEM (ADS)

[B]

[A]

A246D545.WMF

In ADS mode, the ADS sensor [A] detects the density of the original background [A]. The main CPU determines an appropriate development bias voltage for the original to prevent dirty backgrounds from appearing on copies.

The ADS sensor board is on the rear side of the optics side plate. The sensor housing cover, which has a small hole to direct the reflected light from the original to the ADS sensor, covers the sensor board.

The machine adjusts the ADS sensor standard voltage to 2.7 V when process control data initialization is performed. The exposure lamp turns on with ID level 4 at the home position and the light reflected by the ADS pattern [B] (white painted) reaches the ADS sensor. The main CPU adjusts the ADS gain data automatically to make the output 2.7 V. The RAM board stores this data.

2-44

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21 September 1998 OPTICS

9.7

(mm)

90 mm

M=1.0 (m=50~100)

(m=101~200)

100

20 mm

8.25 x100 (mm)

m: reproduction ratio (50~200)

[V]

ADS Original Voltage

Detailed

Descriptions

ADS Sensor Output

Peak hold

A246D546.WMF

For the first scanning of an original in ADS mode, the CPU starts sampling the ADS sensor output while exposing the ADS pattern at the scanner home position. Then the CPU stores the maximum ADS sensor output as a reference voltage. This means that during every ADS check cycle the ADS reference voltage is renewed. It is renewed by the latest exposure light reflected from the ADS pattern when the original is first scanned.

In the full-size mode, the CPU takes samples from the ADS sensor output when the scanner scans the original from 9.7 mm to 18 mm from the left scale edge. The CPU takes the maximum ADS sensor output during the sampling period and compares it with the ADS reference voltage to determine the correct developmentbias voltage. (See development bias control section for details.)

The sampling length of ADS sensor output for the original differs depending on the reproduction ratio because scanner speed differs.

2-45

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OPTICS 21 September 1998

2.4.9 MANUAL IMAGE DENSITY CONTROL

When the image density is set manually, the voltage applied to the exposure lamp changes as shown in the table below.

Lighter Darker

–150

GRID

Grid Bias Voltage (negative)

Exposure Lamp Voltage

V V

GRID

LAMP LAMP

LAMP

–90 –60

GRID

+5.0 +4.0

+2.0

LAMP

GRID

–0.5

LAMP

–1.5

LAMP

–3.5

LAMP

–5.5

LAMP

–7.5

LAMP

9 8

7 6 5 4 3 2 1

Manual ID Position

A246D547.WMF

: Exposure lamp voltage at ID level 5.

The initial setting for the process control data determines this value.

: Grid bias (negative) voltage at ID level 5.

This value is determined at the initial setting of the process control data.

2-46

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21 September 1998 OPTICS

2.4.10 UNEVEN LIGHT INTENSITY CORRECTION

Exposure intensity

Original

Illustration

Shading plate

distribution

Detailed

Descriptions

[A] [B] [C]

A246D549.WMF

- EU and Asia - - U.S.A. -

[D]

A246D662.WMF

A246D548.WMF

The entire surface of the exposure lamp is frosted to ensure even exposure. A shading plate in front of the lens compensates for the reduced light at the edge

of the lens. The shading plate is fixed to the lens unit. The shading plate compensates for the light intensity when the horizontal lens position shifts (from [A] to [C]).

Also, the shading mylars [D] intercept any diffused reflected light from outside the light path.

2-47

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OPTICS 21 September 1998

2.4.11 ORIGINAL SIZE DETECTION IN PLATEN MODE

[D]

[C]

[A]

A246D509.WMF

[B]

A246D511.WMF

[H]

[E]

[J]

[G]

[I]

[F]

A246D510.WMF

A246D669.WMF

The APS sensor [A] in the optics cavity detects the size of the original by scanning it on the exposure glass.

The APS sensor emits two beams of light onto the exposure glass. The APS sensor receives the reflected light from the exposure glass. The machine measures the period from when the APS sensor detects the start plate [B] until it detects the original. It does this for each beam. When the period for beam 1 [C] is longer than for beam 2 [D], the original is lengthwise. Otherwise, it is sideways. The results from beam 1 determine the size of the original. The beam from the LED [E] goes to the partially reflecting mirror [G]. This mirror sends the beam to the spinning mirror [H], then to the exposure glass. The exposure glass reflects the image back to the spinning mirror [H], which sends it to the lens [I] and finally it reaches the light receiving element [F]. The rotating the spinning mirror creates beam arcs. The spinning mirror has two mirrors at different angles to emit two beams every rotation. SP mode 2-3-2 displays the size detected by the APS sensor. SP modes 2-3-3 and 2-3-4 display the pulses and counts detected by APS beam 1 and 2. There is also a reflective sensor [J] in the optics cavity for Inch version copiers. It distinguishes original size LG (8 (8

" x 11"), or F (8

1/2

" x 13") from LT (8

1/2

" x 11").

1/2

" x 14") from LT

1/2

2-48

Page 80

21 September 1998 OPTICS

Beam 1

standard

Beam 2

standard

Beam 1 tolerance

(Metric ver.)

Beam 1 tolerance

(Inch ver.)

A3 505 518 110 — 11" x 7" 845 843 — 77 8 k 1,079 1,067 89 — B4 1,280 1,258 71 — 10" x 14" 1,341 1,317 — 122 8

" x 11" 2,161 2, 096 57 standard

1/2

A4L 2,300 2,227 standard — 8" x 10" 2,466 2,384 — 144 16 k-L 2,661 2,567 99 — B5L 2,993 2,878 156 — A5L 3,983 3,792 194 — 5

1/2

" x 8

" 4, 254 4, 037 — 208

1/2

B6L 4,709 4,438 240 — A6L 5,940 5,411 438 — 11" x 8

" 845 1,669 77 116

1/2

A4S 1,490 2,031 473 — 16 k-S 2,388 2,713 243 — B5S 2,936 3,184 195 — A5S 4,028 4,174 170 — 8

1/2

" x 5

" 4, 246 4, 376 — 162

1/2

B6S 4,554 4,664 150 — A6S 5,097 5,411 134 —

Detailed

Descriptions

L: Lengthwise S: Sideways

NOTE:

" x 13" and 8

1/2

" x 14" tolerance values are the same as 8

1/2

" x 11".

1/2

Check the APS sensor condition using the above table. The tolerance is the standard after APS size calibration (SP1-10-1). After APS size calibration and the correct placement of the original on the ex posure gl ass, if the dat a from bea m 1 is not within the tolerance, the APS sensor is deemed defective.

2-49

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OPTICS 21 September 1998

2.4.12 HALF TONE MODE

A246D553.WMF

This machine has a half-ton e mo de. In thi s mode, selected in the operation panel , the grid voltage for the charge corona is decreased by 200 V. However, this voltage may blank out low-density areas of the original. Decreasing the exposure lamp voltage by 3V corrects this problem. Consequently, this process lowers the image density for picture and half-tone originals.

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21 September 1998 DEVELOPMENT

2.5 DEVELOPMENT

2.5.1 OVERVIEW

[L]

[G]

[F]

[B]

[L]

[C]

[J]

Detailed

Descriptions

[A]

A246D622.WMF



Paddle Roller [A]



Upper Development Roller [B]



Lower Development Roller [C]



Toner Density Sensor [D]



Developer Agitator [E]



Toner Auger [F]

[E][D]

     

[H]

[I]

A246D640.WMF

Development Filter [G] Toner Supply Motor [H] Toner End Sensor [I] Toner Agitator [J] Toner Supply Roller [K] Toner Hopper [L]

[K]

This copier uses a double roller development (DRD) system. Each roller has a diameter of 20 mm.

This system differs from single roller development systems in that: (1) It develops the image in a narrower area (2) It develops the image twice (3) There is a reduction in the relative speed for each development roller touching

the drum

In addition, this machine uses fine toner (about 7.5 m) and developer (about 70



m). Both the DRD system and the new consumables (developer and toner) improve the image quality, especially of thin horizontal lines, the trailing edges of the half-tone areas, and black cross points.

The machine contains a toner-recycling system. The toner-recycling motor carries the recycled toner to the toner hopper [L] and mixes it with new toner using the toner agitator [J]. (The “Drum Cleaning and Toner-recycling section” describes the toner-recycling system.)

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DEVELOPMENT 21 September 1998

2.5.2 DEVELOPMENT MECHANISM

[C]

[B]

[D]

[A]

A246D643.WMF

The paddle roller [A] picks up developer and transports it to the upper-development roller [B]. Internal permanent magnets in the development rollers attract the developer to the development roller sleeve. The upper development roller carries the developer past the doctor blade [C]. Th e doctor blade tri ms the dev eloper to the desired thickness and creates backspill for the cross-mixing mechanism.

The development rollers continue to turn, carrying the developer to the OPC drum [D]. When the developer brush comes in contact with the drum surface, the negatively charged areas of the drum surface attract and hold the positively charged toner. In this way, the latent image is developed.

The development roller has a negative bias to prevent the toner from attracting to the non-image areas on the drum surface that may have a slight residual negative charge.

After turning another 100 degrees, the developer returns to the paddle roller [A].

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21 September 1998 DEVELOPMENT

2.5.3 DRIVE MECHANISM

[C]

[D]

[E]

[A]

[B]

A246D555.WMF

The development drive gear [A] drives the gears of the development unit when the development motor [B] (a DC servomotor) turns.

The drive gear [C] for the toner supply roller drives the gears of the toner hopper when the toner supply clutch [D] activates.

The above gears are helical gears. Helical gears are quieter than normal gears. The teeth of the development drive gear are chamfered, beveled symmetrically, so that they smoothly engage the development roller gear [E] during installation.

Detailed

Descriptions

2-53

Page 85

DEVELOPMENT 21 September 1998

2.5.4 CROSSMIXING

[C][B]

[E]

[F]

[A]

[D]

[E]

A246D556.WMF

[C]

[B]

[F]

[A]

A246D557.WMF

[D]

This copier uses a standard cross-mixing mechanism to keep the toner and developer evenly mix ed. It also helps agitate the developer to prev ent developer clumps from forming and helps create the triboelectric charge, an electric charge generated by friction.

The developer on the turning development rollers [A] is split into two parts by the doctor blade [B]. The part that stays on the development rollers forms the magnetic brush and develops the latent image on the drum. The part that the doctor blade trims off goes to the backspill plate [C].

As the developer slides down the backspill plate to the agitato r [D], the mixing vanes [E] move it slightly toward the rear of the unit. Part of the developer falls into the auger inlet and the auger [F] transmits it to the front of the unit.

The agitator moves the developer slightly to the front as it turns, so the developer stays level in the development unit.

2-54

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21 September 1998 DEVELOPMENT

2.5.5 DEVELOPMENT BIAS

Overview

[B] [C]

Detailed

Descriptions

[A]

A246D558.WMF

The high voltage control Board [A] applies the negative development bias to both the lower sleeve roller and upper sleeve roller through the receptacles [B] and the sleeve roller shaft [C].

The development bias prevents toner from attracting to the background of the nonimage area on the OPC drum where there is residual voltage. In addition, the development bias adjusts image density according to the conditions the customer selected.

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DEVELOPMENT 21 September 1998

Bias Control In Copy Cycle

Five factors determine the bias output: The total bias is:

ADS Mode: V

= VBB + VBU + V

Manual ID Mode: VB = VBB + VBU + V

BMG

+ V

BMG

VB: Total bias VBB: Base bias VBA: ADS Compensation VBU: User Tool mode ID Selection Compensation V

: Magnification Compensation

BMG

1) Base Bias (VBB)

Drum Potential

Dark

Original density

A246D559.WMF

Light

As explained in the process control section, the residual voltage (VR) measured during process control data initialization determines the base bias for development.

= VR + (–220)

2) ADS Compensation (V

)

V (negative)

–300

Dark

122.3

1.02 V

ADS

(V) Light

A246D560.WMF

According to the original background density, the bias is compensated. The compensation value is determined with the voltage measured by the ADS sensor (ADS sensor output: V

= 234 x (V

NOTE:

has a limited range from 0V to –300V.

) as follows:

ADS

–2.3)

ADS

2-56

Page 88

21 September 1998 DEVELOPMENT

(neg

)

3) Manual ID Selection Position Compensation (VBM) This machine does not shift the bias according to the manual ID selection position.

The grid voltage and exposure lamp voltage shift to control the image density. Refer to the optics section.

4) User Tool Mode ID Selection Compensation (VBU) In User Tool mode, there are 7 selectable steps for the image density level. The

User Tool ID position setting determines the VBU as follows:

hter Darker

–90

ative

–60 –30

7654321

Detailed

Descriptions

+30 +60 +90

User Tool ID Position

A246D562.WMF

2-57

Page 89

DEVELOPMENT 21 September 1998

5) Magnification Compensation (V

BMG

)

The selected reproduction ratio determines V

–100

Dev. Bias Voltage (negative)

–60 –40

–30 –20

50% 61%

62%

80%

81%

116%

115%

as follows:

BMG

123% 142% 161%

122% 141% 160%

A246D563.WMF

Bias Control Out of Copy Cycle

To hold the toner on the sleeve rollers while they are rotating without image development, “VB + (–60 V)” is applied.

2-58

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21 September 1998 DEVELOPMENT

ID Sensor Pattern Bias



Potential

Sensor Detection



ID Sensor

Bias Level

4.0 V



ID Sensor

Output

–800



Detailed

IDB

= VP + 300 (V)

Descriptions



–300

A246D564.WMF



A246D565.WMF

While developing the ID sensor pattern, ID sensor bias is applied. ID sensor bias is determined during the process control initial setting as follows:

A charge is applied while grid voltage is –800 V to create the ID sensor pattern. The drum potential (VP) of the ID sensor pattern is checked. The ID sensor bias (V

= VP – (–300)

IDB

) is adjusted to satisfy the following formula:

IDB

= VP + 300 (V)

VP Auto Shift (SP1-16-1)

The triboelectric charge generated on the toner and carrier become greater in accordance with the copy quantity and is stabilized 450 minutes later after the developer initial setting. The value of the VP is compensated as shown in the table.

Period of the development motor rotation after developer initial setting

Added value to VP value +40 V +30 V +20 V 0 V

0 ~ 420 420 ~ 430 430 ~ 440 450 ~

2-59

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DEVELOPMENT 21 September 1998

2.5.6 TONER SUPPLY

Toner Supply Mechanism

[B]

A246D644.WMF

[F]

[B]

[A]

[C]

[E]

[D]

[F]

[G]

A246D645.WMF

When the toner supply clutch [A] turns on, the agitator [B] mixes the recycled toner transported by the air tube [G] with new toner. Then it moves the toner from the front to the rear and sends it to the toner supply roller.

The toner supply clutch [A] located inside the development motor [C] applies the rotation from the development motor to the toner supply roller gear [D], which drives the agitator gear [E]. The grooves on the toner supply roller [F] catch the toner. Then, as the grooves turn past the opening, the toner falls into the development unit.

2-60

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21 September 1998 DEVELOPMENT

Toner End Detection

[A]

Detailed

Descriptions

A246D567.WMF

The toner end sensor [A] detects if sufficient toner remains in the toner hopper. The toner end sensor monitors the toner end-condition when the toner supply clutch turns on. When there is only a little toner inside the toner hopper and toner pressure on the toner end sensor is low, the toner end sensor outputs a pulse signal for each copy (one detection per one copy).

The LCD displays the toner near end indication after receiving the pulse signal 150 times. If a pulse signal is not output twice continually, the pulse count is canceled.

Fifty copies are allowed after entering toner near-end condition. After fifty copies are made in toner near-end condition, the machine enters the toner end-condition and copying is prohibited.

After turning the main switch off and on, or opening and closing the front door, the machine drives the toner supply mechanism and monitors the toner end sensor output. If the toner end sensor does not output the pulse signal twice continually, the toner end condition is canceled.

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DEVELOPMENT 21 September 1998

Bottle Drive Mechanism

[D]

[C]

[A]

[B]

A246D646.WMF

[A]

A246D647.WMF

The drive mechanism for the bottle transports toner from the bottle to the toner supply unit [A]. A worm gear [B] on the toner-supply motor [C] drives this mechanism. The toner bottle [D] has a spiral groove that helps move toner to the supply unit.

When the toner bottle holder is opened, the shutter hook [E] moves the toner shutter, which closes the toner supply unit and prevents the toner in the toner holder from spilling out.

[E]

The drive motor for the bottle turns on after 1.1 seconds when the toner end sensor turns on five times continually.

2-62

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21 September 1998 DEVELOPMENT

Toner Supply Control

By using an SP mode (SP1-13-1), 3 kinds of toner-supply controls are available:



Auto Process Control Mode



Detect Mode



Fixed Mode

1) Auto Process Control Mode

Originals have various image proportions and image densities. To control the toner supply in the best manner, it is necessary to link the amount of toner supplied on each copy cycle to the amount of toner consumed for each copy. This model uses

Fuzzy Control

Fuzzy Control 1

According to the TD sensor data, the CPU checks the following at every copy cycle:

1. The results from the toner supply control process (TD sensor output) in the previous copy cycle.

2. How quickly the toner density is changing. Then the CPU decides the appropriate amount of toner (toner supply clutch ON period) for the next copy cycle by using Fuzzy Logic.

to provide this kind of toner supply control.

Detailed

Descriptions

Fuzzy Control 2

The image on the OPC drum changes due to variations in toner chargeability (influenced by the environment) even if toner concentration is constant. The ID sensor directly checks the image on the OPC drum and shifts the V data under fuzzy control to keep the image on the OPC drum constant.

NOTE:

The toner supply amount changes every copy cycle. The target toner density sensor output is updated under the following conditions:

1) During toner density sensor initialization

2) During process control data initialization

3) After the copy job is completed in case that 10 or more copies have been made since the last update. (Refer to section 2.1.4 “Image Density Control” for details.)

2) Detect Mode In this mode, only the TD sensor controls the toner concentration (V

REF

fixed). The machine only performs Fuzzy Control 1. When the ID sensor detects an abnormal condition, the machine automatically enters this mode.

3) Fixed Mode In this mode, the SP mode determines the fixed amount of toner (4%, 7%, 11%, 14%) supplied every copy cycle (SP1-13-3). There is no over-toning detection mechanism. When the TD sensor or Drum Potential sensor detect an abnormal condition, the machine automaticall y enters this mode.

REF

data is

2-63

Page 95

IMAGE TRANSFER

2.6 IMAGE TRANSFER

2.6.1 PRE-TRANSFER LAMP

21 September 1998

[A]

A246D569.WMF

The pre-transfer lamp [A] located in the drum unit prevents incomplete toner transfer.

The pre-transfer lamp illuminates the drum surface after developing the latent image but before trans ferring the image to the copy paper. This illumination reduces the negative potential on the drum surface, charged by the main charge corona and partially discharged by the exposure. This makes image transfer easier.

The pre-transfer lamp is turned on and off by the charge power pack at the same time as when the main motor turns on and off.

2-64

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21 September 1998

IMAGE TRANSFER

2.6.2 IMAGE TRANSFER AND PAPER SEPARATION OVERVIEW

[A]

[B]

[E]

[C]

[F]

[D]

A246D570.WMF

This model uses a transfer belt unit consisting of the following parts: [A]: Transfer belt

A belt (length: 321 mm) with high electrical resistance which holds a high negative electrical potential and attracts the toner on the OPC drum onto the paper. Also the electrical potential attracts the paper itself and helps paper separation from the OPC drum.

[B]: Transfer bias roller

Applies transfer voltage to the transfer belt.

Detailed

Descriptions

[C]: Transfer belt lift lever (driven by a solenoid)

Lifts the transfer belt to contact the transfer belt with the OPC drum.

[D]: Transfer power pack

Generates the constant transfer current.

[E]: Transfer belt cleaning blade

Removes toner attached on the transfer belt to prevent stains on the rear side of the paper.

[F]: Transfer belt cleaning bias roller and bias roller blade

Even if the toner is not removed completely by the transfer belt cleaning blade, the toner is attracted to the negative charged cleaning bias roller. The bias roller blade scrapes off the toner on the cleaning bias roller.

2-65

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IMAGE TRANSFER

21 September 1998

2.6.3 IMAGE TRANSFER AND PAPER SEPARATION MECHANISM

[C]

[D]

[A]

[B]

[A]

A246D571.WMF

The registration rollers [A] start feeding the paper [B] into the gap between the OPC drum [C] and the transfer belt [D] at the proper time.

[E]

A246D572.WMF

When the leading edge of the paper reaches the gap between the transfer belt and the OPC drum, the transfer belt lift lever [E] immediately raises the transfer belt into contact with the transfer belt and the OPC drum. A solenoid drives the lift lever.

[F]

[G]

A246D573.WMF

Then a negative transfer bias is applied to the transfer bias roller [F] and attracts the positively charged toner [G] on the OPC drum. It also attracts the paper and separates the paper from the OPC drum.

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Page 98

21 September 1998

A246D574.WMF

[A]

It + I1 = I

IMAGE TRANSFER

After the image transfer is completed, the charge on the transfer belt holds the paper on the transfer belt. After separating the paper from the transfer belt, the transfer belt drive roller [A] discharges the transfer belt.

Detailed

Descriptions

[C]

[D]

[B]

[A]

[E]

The transfer power pack [B] inside the transfer belt unit monitors the current (

A246D575.WMF

) fed back from the drive rollers at each end of the transfer belt to adjust the transfer current.

Then, the power pack adjusts it to maintain a constant current through the drum

(

), even if the paper, environmental conditions, or transfer belt surface resistance

change. 4/5 of the voltage for the transfer belt bias roller is applied to the transfer belt

cleaning bias roller [C] through the cleaning bias terminal [D] from the power pack. The grounding terminal [E] grounds the transfer belt drive roller.

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Page 99

IMAGE TRANSFER

2.6.4 TRANSFER BELT UNIT LIFT MECHANISM

[C]

[A]

[E]

[B]

[F]

21 September 1998

[E]

[D]

A246D576.WMF

The transfer belt lift solenoid [A] located inside the transfer belt unit turns on to raise the transfer belt into contact with the OPC drum at the appropriate time. Links [D] connect the front lever [B] and the rear lever [C] to the solenoid and push up the stays [E] when the solenoid turns on. The support spring [F] helps the solenoid to raise the transfer belt. The solenoid turns off after the copy job is finished. The transfer belt must be released from the OPC drum for the following reasons:

1. To prevent the ID sensor pattern on the OPC drum from being rubbed by the

transfer belt because the transfer belt is located between the development unit and the ID sensor.

2. To decrease the load sent to the transfer belt-cleaning blade, it is better to keep

toner on the non-image area (for example VD, VL, ID sensor pattern developed during process control data initialization) from being transferred onto the transfer belt.

3. To prevent changes to OPC drum characteristics influenced by additives inside

the rubber belt.

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21 September 1998

IMAGE TRANSFER

2.6.5 PAPER TRANSPORTATION AND BELT DRIVE MECHANISM

[B]

A246D577.WMF

[C]

[A]

Detailed

Descriptions

[F]

[E]

[D]

A246D578.WMF

The main drive motor [A] drives the transfer belt through the belt and gears. Since the transfer belt electrically attracts the paper [B], the transport fan is not required.

At the turn in the transfer belt, the belt is discharged by the transfer belt drive roller [C] to reduce paper attraction, and the paper separates from the belt as a result of its own stiffness.

The tapered parts [D] at both sides of the roller [E] help keep the transfer belt [F] in the center, so that it does not run off the rollers.

2-69

Ricoh Ft7950 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

TABLE OF CONTENTS

IMPORTANT SAFETY NOTICES

1. OVERALL MACHINE INFORMATION

1.1 SPECIFICATION

1.2 MACHINE CONFIGURATION

1.2.1 COPIER OVERVIEW

1.2.2 SYSTEM OVERVIEW

1.3 COPY PROCESS AROUND THE DURM

1.4 MECHANICAL COMPONENT LAYOUT

1.5 DRIVE LAYOUT

1.6 PAPER PATH

1.6.1 STANDARD COPYING

1.6.2 MULTIPLE 2-SIDE COPYING

1.7 ELECTRICAL COMPONENT DESCRIPTION

2. DETAILED SECTION DESCRIPTIONS

2.1 PROCESS CONTROL

2.1.1 OVERVIEW

2.1.2 PROCESS CONTROL DATA INITIAL SETTING

2.1.3 LATENT IMAGE CONTROL

2.1.4 IMAGE DENSITY CONTROL

2.2 DRUM UNIT

2.2.1 OVERVIEW

2.2.2 OPC DRUM CHARACTERISTICS

2.2.3 DRUM CHARGE

2.2.4 ERASE

2.2.5 CLEANING

2.2.6 QUENCHING

2.3 DRUM CLEANING AND TONER-RECYCLING

2.3.1 TONER TRANSPORT

2.3.2 FILTERING

2.3.3 PUMP MECHANISM

2.3.4 DRIVE MECHANISM

2.3.5 TONER COLLECTION BOTTLE

2.4 OPTICS

2.4.1 OVERVIEW

2.4.2 SCANNER DRIVE

2.4.3 VERTICAL LENS DRIVE

2.4.4 HORIZONTAL LENS DRIVE

2.4.5 HORIZONTAL LENS POSITIONING

2.4.7 OPTICS CONTROL CIRCUIT

2.4.8 AUTOMATIC IMAGE DENSITY CONTROL SYSTEM (ADS)

2.4.9 MANUAL IMAGE DENSITY CONTROL

2.4.10 UNEVEN LIGHT INTENSITY CORRECTION

2.4.11 ORIGINAL SIZE DETECTION IN PLATEN MODE

2.4.12 HALF TONE MODE

2.5 DEVELOPMENT

2.5.1 OVERVIEW

2.5.2 DEVELOPMENT MECHANISM

2.5.3 DRIVE MECHANISM

2.5.4 CROSSMIXING

2.5.5 DEVELOPMENT BIAS

2.5.6 TONER SUPPLY

2.6 IMAGE TRANSFER

2.6.1 PRE-TRANSFER LAMP

2.6.2 IMAGE TRANSFER AND PAPER SEPARATION OVERVIEW

2.6.3 IMAGE TRANSFER AND PAPER SEPARATION MECHANISM

2.6.4 TRANSFER BELT UNIT LIFT MECHANISM

2.6.5 PAPER TRANSPORTATION AND BELT DRIVE MECHANISM