Konica Minolta BIZHUB 750 Service Manual
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Konica Minolta BIZHUB 750 Service Manual

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See also: Function Manual , System Administrator Manual
SERVICE MANUAL
Theory of Operation
750/600

Main body

2005.08
Ver. 1.0

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Summary of Contents for Konica Minolta BIZHUB 750

  • Page 1: Main Body

    SERVICE MANUAL Theory of Operation 750/600 Main body 2005.08 Ver. 1.0...
  • Page 2 Because of possible hazards to an inexperienced person servicing this product as well as the risk of damage to the product, Konica Minolta Business Technologies, INC. (hereafter called the KMBT) strongly recommends that all servicing be performed only by KMBT- trained service technicians.

  • Page 3: Safety Warnings

    [1] MODIFICATIONS NOT AUTHORIZED BY KONICA MINOLTA BUSINESS TECHNOLOGIES, INC. Konica Minolta brand products are renowned for their high reliability. This reliability is achieved through high-quality design and a solid service network. Product design is a highly complicated and delicate process where numerous mechanical, physical, and electrical aspects have to be taken into consideration, with the aim of arriving at proper tolerances and safety factors.
  • Page 4 SAFETY AND IMPORTANT WARNING ITEMS [2] POWER PLUG SELECTION In some countries or areas, the power plug provided with the product may not fit wall outlet used in the area. In that case, it is obligation of customer engineer (hereafter called the CE) to attach appropriate power plug or power cord set in order to connect the product to the supply.
  • Page 5 SAFETY AND IMPORTANT WARNING ITEMS [3] CHECKPOINTS WHEN PERFORMING ON-SITE SERVICE Konica Minolta brand products are extensively tested before shipping, to ensure that all applicable safety standards are met, in order to protect the customer and CE from the risk of injury.
  • Page 6 SAFETY AND IMPORTANT WARNING ITEMS Connection to Power Supply WARNING • Check whether the product is grounded properly. If current leakage occurs in an ungrounded product, you may suffer electric shock while operating the product. Connect power plug to grounded wall outlet. Power Plug and Cord WARNING •...
  • Page 7 SAFETY AND IMPORTANT WARNING ITEMS Power Plug and Cord WARNING • Check whether dust is collected around the power plug and wall outlet. Using the power plug and wall outlet without removing dust may result in fire. • Do not insert the power plug into the wall outlet with a wet hand.
  • Page 8 SAFETY AND IMPORTANT WARNING ITEMS Installation Requirements Prohibited Installation Places WARNING • Do not place the product near flammable materials or vola- tile materials that may catch fire. A risk of fire exists. • Do not place the product in a place exposed to water such as rain.
  • Page 9 SAFETY AND IMPORTANT WARNING ITEMS Inspection before Servicing CAUTION • Before conducting an inspection, read all relevant docu- mentation (service manual, technical notices, etc.) and proceed with the inspection following the prescribed pro- cedure in safety clothes, using only the prescribed tools. Do not make any adjustment not described in the docu- mentation.
  • Page 10 SAFETY AND IMPORTANT WARNING ITEMS Safety Checkpoints WARNING • Check the exterior and frame for edges, burrs, and other damages. The user or CE may be injured. • Do not allow any metal parts such as clips, staples, and screws to fall into the product. They can short internal circuits and cause electric shock or fire.

  • Page 11: Handling Of Consumables

    SAFETY AND IMPORTANT WARNING ITEMS Safety Checkpoints WARNING • When replacing a lithium battery, replace it with a new lith- ium battery specified in the Parts Guide Manual. Dispose of the used lithium battery using the method specified by local authority. Improper replacement can cause explosion.
  • Page 12 SAFETY AND IMPORTANT WARNING ITEMS Handling of Consumables WARNING • Never throw the used cartridge and toner into fire. You may be burned due to dust explosion. Handling of Service Materials CAUTION • Unplug the power cord from the wall outlet. Drum cleaner (isopropyl alcohol) and roller cleaner (ace- tone-based) are highly flammable and must be handled with care.
  • Page 13 SAFETY INFORMATION SAFETY INFORMATION IMPORTANT NOTICE The Center for Devices and Radiological Health (CDRH) of the U.S. Food and Drug Admin- istration implemented regulations for laser products manufactured since August 1, 1976. Compliance is mandatory for products marketed in the United States. This copier is certified as a "Class 1"...

  • Page 14: Indication Of Warning On The Machine

    SAFETY INFORMATION INDICATION OF WARNING ON THE MACHINE Caution labels shown below are attached in some areas on/in the machine. When accessing these areas for maintenance, repair, or adjustment, special care should be taken to avoid burns and electric shock. For metric area: DO NOT INSERT your finger into...
  • Page 15 SAFETY INFORMATION For inch area: DO NOT INSERT your finger into the two EDH hinge portions; otherwise you may be injured. High voltage is present around this part. DO NOT put your hand Do not touch this part between the main body and in order to reduce the risk developing fixing unit;...
  • Page 16 MEASURES TO TAKE IN CASE OF AN ACCIDENT MEASURES TO TAKE IN CASE OF AN ACCIDENT 1. If an accident has occurred, the distributor who has been notified first must immediately take emergency measures to provide relief to affected persons and to prevent further damage.
  • Page 17 MEASURES TO TAKE IN CASE OF AN ACCIDENT Blank page S-16...

  • Page 18: Composition Of The Service Manual

    Composition of the service manual This service manual consists of the following sections and chapters: <Theory of Operation section> OUTLINE: System configuration, product specifications, unit configuration, and paper path COMPOSITION/OPERATION: Configuration of each unit, explanation of the operating system, and explanation of the control system This section gives, as information for the CE to get a full understanding of the product, a rough outline of the object and role of each function, the relationship between the electrical system and the mechanical system, and the timing of operation of each part.

  • Page 19: Notation Of The Service Manual

    Notation of the service manual A. Product name In this manual, each of the products is described as follows: (1) IC board: Standard printer (2) bizhub 750/600: Main body (3) PS-502 PostScript3 Option: PS3 Option (4) Microsoft Windows 95: Windows 95...
  • Page 20 Classification Load symbol Ex. of signal name Description Power to drive the motor CONT Drive signal DRV1 Motor DRV2 Drive signals of two kinds Drive signals (control signals) of three kinds DRV1 DRV2 DRV3 DRV A DRV A DRV B Drive signals (control signals) of four kinds Motor, phases A and B control signals DRV B...
  • Page 21 Classification Load symbol Ex. of signal name Description SG, S.GND, S_GND Signal ground Ground PG, P.GND Power ground Data carrier detection Serial input SOUT Serial output Data terminal operation available Signal ground (earth) Serial com- DSR, DSET Data set ready munication Transmission request signal Consent transmission signal...

  • Page 22: Revision History

    Revision history After publication of this service manual, the parts and mechanism may be subject to change for improvement of their performance. Therefore, the descriptions given in this service manual may not coincide with the actual machine. When any change has been made to the descriptions in the service manual, a revised version will be issued with a revision mark added as required.

  • Page 23: Table Of Contents

    CONTENTS CONTENTS bizhub 750/600 OUTLINE 1. SYSTEM CONFIGURATION ............1 2.
  • Page 24 CONTENTS Theory of Operation Ver1.0 Aug.2005 10.2 Drive ............... . . 29 10.3 Operation .
  • Page 25 Theory of Operation Ver1.0 Aug.2005 CONTENTS 15.3.6 Dehumidification heater control ..........53 16.
  • Page 26 CONTENTS Theory of Operation Ver1.0 Aug.2005 21.3.4 Fusing conveyance mechanism ..........84 22.

  • Page 27: Outline

    Theory of Operation Ver1.0 Aug.2005 1. SYSTEM CONFIGURATION OUTLINE 1. SYSTEM CONFIGURATION A. System configuration [11] [12] [16] [13] [15] [14] [10] 57aat1c001na Main body 50 sheet staple flat stapling finisher (FS-504) Double sided original auto feeder (DF-604) [10] Stitch-and-fold finisher (FS-602) Volume paper feed tray (LU-401) [11] Key counter...
  • Page 28 1. SYSTEM CONFIGURATION Theory of Operation Ver1.0 Aug.2005 B. Configuration for optional device connection NOTE • For machines equipped with ZU-601/602, the function of PK-502/503/504/505 is not available when PI-501 is not equipped. • Any combination other than those listed below is not available. Combinations of finishing AC power to be connected to FS-504/FS-602...

  • Page 29: Product Specifications

    Theory of Operation Ver1.0 Aug.2005 2. PRODUCT SPECIFICATIONS 2. PRODUCT SPECIFICATIONS A. Type Type Console type (floor-mount type) Copying method Indirect electrostatic method Original stand Fixed Original alignment Left rear standard Photosensitive material Sensitizing method Laser writing Paper feed trays Four trays (1,500 sheets x1, 1,000 sheets x 1, 500 sheets x 2: 80 g/m Bypass feed (100 sheet x 1: 80 g/m LU-401 (5,000 sheet x 1: 64 g/m...
  • Page 30 2. PRODUCT SPECIFICATIONS Theory of Operation Ver1.0 Aug.2005 Magnification Fixed magnification Inch: x 1.000, x 1.214, x 1.294, x 1.545, x 2.000, x 0.785, x 0.772, x 0.647, x 0.500 Metric: x 1.000, x 1.154, x 1.224, x 1.414, x 2.000, x 0.866, x 0.816, x 0.707, x 0.500 Special magnifica- x 0.930 (can be changed between x 0.900 and x 0.999)
  • Page 31 200 g/m (thick paper) Standard specified paper Inch: Hammermill Tidal MP (75 g/m ), Whyerhaeuser Recycled Laser Copy Metric: Konica Minolta Profi (80 g/m ), Konica Minolta Original (80 g/m ), Classic White Special paper/recommended paper Thick paper: Inch:...

  • Page 32: Unit Configuration

    3. UNIT CONFIGURATION Theory of Operation Ver1.0 Aug.2005 3. UNIT CONFIGURATION [16] [15] [17] [14] [13] [12] [11] [10] 57aat1c002na Photo conductor section [10] Paper feed section (trays 3, 4) Toner supply section [11] Paper feed section (trays 1, 2) Developing unit [12] Paper reverse/exit section...

  • Page 33: Paper Path

    Theory of Operation Ver1.0 Aug.2005 4. PAPER PATH 4. PAPER PATH [10] [11] 57aat1c003na Tray 1 paper feed Straight paper exit Tray 2 paper feed ADU paper feed Tray 4 paper feed Registration conveyance Tray 3 paper feed [10] Bypass feed Reverse conveyance [11] LU paper feed...
  • Page 34 4. PAPER PATH Theory of Operation Ver1.0 Aug.2005 Blank page...

  • Page 35: Composition/Operation

    Theory of Operation Ver1.0 Aug.2005 5. OVERALL CONFIGURATION COMPOSITION/OPERATION 5. OVERALL CONFIGURATION Time chart when the power is turned ON Time (sec) Item Forward Scanner motor (M1) Reverse Exposure lamp (L1) Fusing heater lamp /1, /2 (L2, L3) Fusing heater lamp /3 (L4) Maximum density correction Gamma correction Fusing motor (M4)
  • Page 36 5. OVERALL CONFIGURATION Theory of Operation Ver1.0 Aug.2005 Power switch (SW2) ON Home position search/shading correction Thermistors /1 (TH1) and /2 (TH2) get to the Image stabilization control specified temperature Warm-up completed OS start-up completed NOTE • Each operation varies with the software DIPSW setting in the service mode and the environmental conditions.

  • Page 37: Control Block Diagram

    Theory of Operation Ver1.0 Aug.2005 5. OVERALL CONFIGURATION Control block diagram RS232C Write Section PRCB ADUDB FS/SF 57aat2c085na Image bus Other buses Parallel bus Individual signal line Clock synchronization serial bus UART bus...

  • Page 38: Scanner Section

    6. SCANNER SECTION Theory of Operation Ver1.0 Aug.2005 6. SCANNER SECTION Composition Shading correction plate Exposure unit Mirror unit CCD unit 57aat2c001na Drive 57aat2c002na Scanner wire /Fr Scanner wire /Rr V-mirror unit Exposure unit Scanner motor (M11)

  • Page 39: Operation

    Theory of Operation Ver1.0 Aug.2005 6. SCANNER SECTION Operation 6.3.1 Scan/exposure lamp control A. Operation when the power is turned ON The home position varies depending on whether DF is open or closed. When DF is open, the home position is at the platen APS read position and when it is closed, the DF read position becomes the home position.
  • Page 40 6. SCANNER SECTION Theory of Operation Ver1.0 Aug.2005 (2) Shading correction After completion of the home position search [4], the exposure unit conducts shading corrections. For shading corrections, there are the following types of corrections: white correction 1 [5], white correction 2 [6], and black correction [7].
  • Page 41 Theory of Operation Ver1.0 Aug.2005 6. SCANNER SECTION B. Operation when the start button is turned ON The operation when the start button is turned ON varies depending on whether DF is open or closed. In either operation, the shading correction is carried out first. However, unlike the operation when the power is turned ON, the exposure unit proceeds to the original read operation with the exposure lamp (L1) left on, and therefore, the black correction is not conducted.
  • Page 42 6. SCANNER SECTION Theory of Operation Ver1.0 Aug.2005 • While in the manual copy When the start button is turned ON [3] while in the manual copy, the exposure unit conducts the white correction 1 [4] and the white correction 2 [5] before the exposure scan [6] is made. After completion of the exposure scan, the home position search [7] is carried out.
  • Page 43 Theory of Operation Ver1.0 Aug.2005 6. SCANNER SECTION (2) When DF is in use (when DF is closed) When the start button is turned ON [4], the exposure unit conducts the white correction 1 [5] and the white cor- rection 2 [6] before moving to the original read position [3]. The same operation is made when AE is selected. The exposure unit stops at the original read position to read the original [7].

  • Page 44: Original Size Detection Control

    6. SCANNER SECTION Theory of Operation Ver1.0 Aug.2005 6.3.2 Original size detection control A. Detection method The detection method of the original size varies with the DF mode and the platen mode. (1) DF mode See DF-604. (2) Platen mode •...

  • Page 45: Ae Control

    Theory of Operation Ver1.0 Aug.2005 6. SCANNER SECTION 6.3.3 AE control When AE is selected, the density level of the original is detected to adjust it automatically to an appropriate den- sity. The sampling area of the original density in the AE control varies with the platen mode and the DF mode. (1) AE sampling area in the platen mode •...

  • Page 46: Write Section

    7. WRITE SECTION Theory of Operation Ver1.0 Aug.2005 7. WRITE SECTION Composition Index board (INDEXB) Collimator lens unit Laser drive board (LDB) CY2 lens CY1 lens θ lens Polygon mirror 57aat2c011na Operation 7.2.1 Laser beam path 57aat2c012na Write mirror Polygon mirror CY2 lens CY1 lens Drum...

  • Page 47: Write Control

    The polygon mirror is driven by the polygon motor (M15) and the number of its rotations changes according to the process speed that varies with the type of paper. A. In the case of bizhub 750 Type of paper Process speed No.

  • Page 48: Photo Conductor Section

    8. PHOTO CONDUCTOR SECTION Theory of Operation Ver1.0 Aug.2005 8. PHOTO CONDUCTOR SECTION Composition Drum Toner control sensor board (TCSB) Suction duct Drum claw 57aat2c013na...

  • Page 49: Drive

    Theory of Operation Ver1.0 Aug.2005 8. PHOTO CONDUCTOR SECTION Drive 8.2.1 Drum drive 57aat2c014na Toner guide roller (TGR) Separation guide plate assembly Toner conveyance screw Drum Drum motor (M2) Toner recycle clutch (CL14)/toner convey- ance screw 8.2.2 Drum claw drive 57aat2c015na Drum claw oscillation cam Separation guide plate assembly...

  • Page 50: Operation

    8. PHOTO CONDUCTOR SECTION Theory of Operation Ver1.0 Aug.2005 Operation 8.3.1 Image creation control When the print start signal turns ON [1], various types of motors turn ON to make each of the units operative. At this time, the erase lamp (EL) also turns ON to start to neutralize [2] the drum. And a specified period of time after this signal is sent, a high voltage impression is made on the charging [3], the developing bias [4], the trans- fer guide [5] and the toner guide roller (TGR) [7] to form images on the drum surface by the laser irradiation and the developing.

  • Page 51: Drum Claw Control

    Theory of Operation Ver1.0 Aug.2005 8. PHOTO CONDUCTOR SECTION 8.3.2 Drum claw control A. Purpose To prevent the occurrence of a drum wrap jam, 3 drum claws are employed to prevent the drum from being wrapped with the paper. The contact and the release of contact of the drum claws onto the drum is made by turning on and off the drum claw solenoid (SD1).

  • Page 52: Image Stabilization Control

    8. PHOTO CONDUCTOR SECTION Theory of Operation Ver1.0 Aug.2005 8.3.4 Image stabilization control There are following items for the image stabilization control. For particulars, see "24. IMAGE STABILIZATION CONTROL." • Environmental decision control • Maximum density control • Gamma correction control A.

  • Page 53: Charging Section

    Theory of Operation Ver1.0 Aug.2005 9. CHARGING SECTION 9. CHARGING SECTION Composition Charge cleaning Charge cleaning Charge wire block /Up block /Lw Charge control plate Erase lamp (EL) Erase lamp (EL) Back plate 57aat2c017na Drive 57aat2c018na Charge cleaning block /Lw Charge control plate Charge cleaning block /Up Charge cleaning motor (M14)

  • Page 54: Operation

    9. CHARGING SECTION Theory of Operation Ver1.0 Aug.2005 Operation 9.3.1 Charging control A. Charge wire The high voltage unit (HV) pressurizes 24V DC to impress a minus (-) DC voltage to the charging wire for dis- charge. µ µ Charging output range: -600 A to -1200 B.

  • Page 55: Transfer/Separation Section

    Theory of Operation Ver1.0 Aug.2005 10. TRANSFER/SEPARATION SECTION 10. TRANSFER/SEPARATION SECTION 10.1 Composition Transfer charge wire Separation cleaning Transfer cleaning assembly assembly Transfer guide plate Wire guide /2 Wire guide /1 Separation charge wire Back plate Transfer exposure lamp (TSL) 57aat2c019na 10.2 Drive 57aat2c020na...

  • Page 56: Operation

    10. TRANSFER/SEPARATION SECTION Theory of Operation Ver1.0 Aug.2005 10.3 Operation 10.3.1 Transfer guide control A. Purpose To prevent the transfer guide from getting soiled, a minus (-) DC voltage is impressed from the high voltage unit (HV). Impressed voltage: -500 V B.

  • Page 57: Wire Cleaning Control

    Theory of Operation Ver1.0 Aug.2005 10. TRANSFER/SEPARATION SECTION 10.3.4 Wire cleaning control A. Purpose To prevent the deterioration of the discharge characteristics caused by soil adhered to the transfer wire and the separation wire, the wire is cleaned periodically. B. Timing •...

  • Page 58: Developing Unit

    11. DEVELOPING UNIT Theory of Operation Ver1.0 Aug.2005 11. DEVELOPING UNIT 11.1 Composition Developer regulation blade Developer Agitator plate 57aat2c022na 11.2 Drive 57aat2c023na Gear for the agitator screw Coupling for developing drive Gear for the agitator plate Developing input gear Gear for the developing roller Developing idler gear Developing motor (M3)

  • Page 59: Operation

    Theory of Operation Ver1.0 Aug.2005 11. DEVELOPING UNIT 11.3 Operation 11.3.1 Conveyance of developer Developer in the developing unit is supplied to the developing roller [3] by the agitator plate [2]. And developer that adheres to the developing roller is kept at a fixed thickness by the developer regulation blade [5]. Developer that remains on the developing roller is returned to the agitator screw [1].

  • Page 60: Developing Suction Control

    11. DEVELOPING UNIT Theory of Operation Ver1.0 Aug.2005 B. Timing To prevent unnecessary carriers from adhering to the drum, the developing bias turns ON a specified period of time after a print start signal is sent, and it turns OFF a specified period of time after the trailing edge of the last paper is detected by the paper leading edge sensor (PS43).

  • Page 61: Toner Supply Section

    Theory of Operation Ver1.0 Aug.2005 12. TONER SUPPLY SECTION 12. TONER SUPPLY SECTION 12.1 Composition Toner bottle Toner hopper Agitator plate Toner remaining sensor (PZS) 57aat2e002na 12.2 Drive 57aat2e003na Front Toner bottle motor (M13) Toner supply motor (M12) Toner bottle Toner conveyance screw Toner conveyance screw Rear...

  • Page 62: Operation

    12. TONER SUPPLY SECTION Theory of Operation Ver1.0 Aug.2005 12.3 Operation 12.3.1 Toner remaining detection control A. Toner remaining detection control The toner remaining in the toner hopper is detected by the toner remaining sensor (PZS). When the toner remaining in the toner hopper gets below the specified amount, a toner supply signal is output to the printer control board (PRCB).

  • Page 63: Toner Conveyance Control

    Theory of Operation Ver1.0 Aug.2005 12. TONER SUPPLY SECTION 12.3.3 Toner conveyance control A. Purpose To convey toner in the toner bottle to the toner hopper. B. Operation The toner bottle set to the toner supply section is rotated when the toner bottle motor (M13) turns ON. When the toner bottle rotates, toner is guided to the exit [1] of the bottle along the spiral groove carved on the surface of the toner bottle.

  • Page 64: Cleaning/Toner Recycle Section

    13. CLEANING/TONER RECYCLE SECTION Theory of Operation Ver1.0 Aug.2005 13. CLEANING/TONER RECYCLE SECTION 13.1 Composition Toner recycle pipe Cleaning blade Toner guide roller (TGR) 57aat2c029na 13.2 Drive 57aat2c030na Drum Toner recycle clutch (CL14) / toner conveyance screw Toner conveyance screw Drum motor (M2) Toner guide roller (TGR)

  • Page 65: Operation

    Theory of Operation Ver1.0 Aug.2005 13. CLEANING/TONER RECYCLE SECTION 13.3 Operation 13.3.1 Toner guide roller control A. Operation To improve the cleaning performance of toner, a fixed voltage is impressed on the toner guide roller (TGR) [1]. A voltage impressed on the TGR is sent to the cleaner power supply shaft /Rr [3] from the high power unit (HV) to be supplied to TGR [1] through the power supply pin [2].

  • Page 66: Paper Feed Section (Trays 1 And 2)

    14. PAPER FEED SECTION (trays 1 and 2) Theory of Operation Ver1.0 Aug.2005 14. PAPER FEED SECTION (trays 1 and 2) 14.1 Composition Horizontal conveyance section Pre-registration roller Tray /1 Lift plate Tray /2 Pick-up roller Feed roller Separation roller Feed roller Pre-registration roller Horizontal conveyance section...

  • Page 67: Drive

    Theory of Operation Ver1.0 Aug.2005 14. PAPER FEED SECTION (trays 1 and 2) 14.2 Drive 14.2.1 Paper feed drive [11] [12] [13] [14] [15] [16] [6] [7] [9] [10] [17] 57aat2c033na Paper feed motor (M1) [10] Pre-registration clutch /1 (CL4), /2 (CL6) Separation clutch /1 (CL21), /2 (CL22) [11] Coupling shaft /1...

  • Page 68: Tray Lift Drive

    14. PAPER FEED SECTION (trays 1 and 2) Theory of Operation Ver1.0 Aug.2005 14.2.2 Tray lift drive 57aat2c034na Paper lift motor /1 (M16) Lift wire Paper lift motor /2 (M17) Lift plate Lift wire...

  • Page 69: Operation

    Theory of Operation Ver1.0 Aug.2005 14. PAPER FEED SECTION (trays 1 and 2) 14.3 Operation 14.3.1 Up/down control A. Up operation The paper lift motors /1 (M16) and /2 (M17) cause the lift wires to be taken up by the pulley to raise the lift plate. B.

  • Page 70: Paper Feed Control

    14. PAPER FEED SECTION (trays 1 and 2) Theory of Operation Ver1.0 Aug.2005 14.3.2 Paper feed control A. Pick-up control The up operation of the lift plate causes the paper and the pick-up roller come into contact. At this time, the pick-up roller pressurizes the paper by its own weight.
  • Page 71 Theory of Operation Ver1.0 Aug.2005 14. PAPER FEED SECTION (trays 1 and 2) B. Separation mechanism The separation roller [4] is driven in the direction opposite [2] to the paper conveyance [10] through the torque limiter [1]. However, it is pressed against the feed roller [8] by the working pressure generated by the pressure [9] of the spring [3] and the torque of the torque limiter.
  • Page 72 14. PAPER FEED SECTION (trays 1 and 2) Theory of Operation Ver1.0 Aug.2005 C. Paper loop mechanism Paper that passed through the feed roller [5] and the separation roller [3] is sent out to the pre-registration roller [7]. The paper thus sent out presses the actuator [1] to turn ON the paper feed sensors /1 (PS1) and /2 (PS7) [6]. By stopping the paper feed roller a specified period of time after PS1 and PS7 turn ON, the paper forms a loop [2] short of the pre-registration roller to correct the skew of paper.

  • Page 73: Paper Empty Detection Control

    Theory of Operation Ver1.0 Aug.2005 14. PAPER FEED SECTION (trays 1 and 2) [3] [4] [5] Paper feed motor (M1) Paper feed clutches /1, /2 (CL3, 5) Pre-registration clutches /1, /2 (CL4, 6) Separation clutches /1, /2 (CL21, 22) Paper feed sensors /1, /2 (PS1, 7) 57aat2c039na Print start signal Assist of the conveyance of the 1st sheet of paper...
  • Page 74 14. PAPER FEED SECTION (trays 1 and 2) Theory of Operation Ver1.0 Aug.2005 Paper feed motor (M1) Horizontal conveyance clutch /Lt (CL15) Horizontal conveyance clutch /Rt (CL16) Horizontal conveyance sensor /Lt (PS5) Horizontal conveyance sensor /Rt (PS6) Registration sensor (PS44) 57aat2c040na Print start signal Detection of the trailing edge of the 1st sheet of paper...

  • Page 75: Paper Feed Section (Trays 3 And 4)

    Theory of Operation Ver1.0 Aug.2005 15. PAPER FEED SECTION (trays 3 and 4) 15. PAPER FEED SECTION (trays 3 and 4) 15.1 Composition Pre-registration roller Pick-up roller Lift plate Feed roller Dehumidification Separation roller Dehumidification 57aat2c041na heater /1 (HTR1) heater /2 (HTR2)

  • Page 76: Drive

    15. PAPER FEED SECTION (trays 3 and 4) Theory of Operation Ver1.0 Aug.2005 15.2 Drive 15.2.1 Paper feed drive [9] [10] [11] [12] [13] 57aat2c042na Coupling shaft /3 Pick-up roller Belt Feed roller Coupling shaft /4 [10] Paper feed clutch /3 (CL7), /4 (CL9) Paper feed motor (M1) [11] Coupling...

  • Page 77: Tray Lift Drive

    Theory of Operation Ver1.0 Aug.2005 15. PAPER FEED SECTION (trays 3 and 4) 15.2.2 Tray lift drive 57aat2c043na Paper lift motor /3 (M18) Lift plate Paper lift motor /4 (M19) Lift wire Lift wire...

  • Page 78: Operation

    15. PAPER FEED SECTION (trays 3 and 4) Theory of Operation Ver1.0 Aug.2005 15.3 Operation 15.3.1 Up/down control A. Up operation The paper lift motors /3 (M18) and /4 (M19) cause the lift wires to be taken up by the pulley to raise the lift plate. B.

  • Page 79: Paper Size Detection Control

    Theory of Operation Ver1.0 Aug.2005 15. PAPER FEED SECTION (trays 3 and 4) 15.3.3 Paper size detection control A. Size detection in the main scan direction The size detection of paper in the main scan direction is made according to the position of the guide plate con- nected to the paper size VR/1 (VR3) and /2 (VR4).

  • Page 80: Bypass Tray

    16. BYPASS TRAY Theory of Operation Ver1.0 Aug.2005 16. BYPASS TRAY 16.1 Composition Paper feed roller Pick-up roller Separation roller Lift plate 57aat2c045na...

  • Page 81: Drive

    Theory of Operation Ver1.0 Aug.2005 16. BYPASS TRAY 16.2 Drive 16.2.1 Paper feed drive 57aat2c046na Separation roller Paper feed roller Belt Pick-up roller Loop motor (M6) 16.2.2 Tray lift drive 57aat2c047na Lift plate Bypass tray lift motor (M20)

  • Page 82: Operation

    16. BYPASS TRAY Theory of Operation Ver1.0 Aug.2005 16.3 Operation 16.3.1 Up/down control A. Up operation The bypass tray lift motor (M20) drives the fan-shaped gear to bring up the lift plate. B. Down operation The bypass tray lift motor (M20) drives the fan-shaped gear to bring down the lift plate. C.

  • Page 83: Paper Feed Control

    Theory of Operation Ver1.0 Aug.2005 16. BYPASS TRAY 16.3.3 Paper feed control A. Pick-up control The up operation of the lift plate causes the paper and the pick-up roller to come into contact. At this time, the pick-up roller pressurizes the paper by its own weight. When a print start signal [1] turns ON [2] the loop motor (M6), the pick-up roller that pressurized the paper rotates and pick up the paper to convey it to the paper feed roller.

  • Page 84: Paper Empty Detection Control

    16. BYPASS TRAY Theory of Operation Ver1.0 Aug.2005 B. Separation mechanism The separation roller [4] is driven in the direction opposite [1] to the paper conveyance [8] through the torque lim- iter [6]. However, it is pressed against the feed roller [10] by the working pressure generated by the pressure [9] of the spring [5] and the torque of the torque limiter.

  • Page 85: Vertical Conveyance Section

    Theory of Operation Ver1.0 Aug.2005 17. VERTICAL CONVEYANCE SECTION 17. VERTICAL CONVEYANCE SECTION 17.1 Composition Vertical conveyance sensor /1 (PS25) Vertical conveyance roller /1 Vertical conveyance sensor /2 (PS26) Vertical conveyance door Vertical conveyance roller /2 Vertical conveyance sensor /3 (PS27) Vertical conveyance sensor /4 (PS28) Vertical conveyance roller /3 57aat2c050na...

  • Page 86: Drive

    17. VERTICAL CONVEYANCE SECTION Theory of Operation Ver1.0 Aug.2005 17.2 Drive 57aat2c051na Vertical conveyance roller /1 Belt Vertical conveyance clutch /1 (CL11) Vertical conveyance roller /3 Vertical conveyance clutch /2 (CL12) Paper feed motor (M1) Vertical conveyance roller /2...

  • Page 87: Operation

    Theory of Operation Ver1.0 Aug.2005 17. VERTICAL CONVEYANCE SECTION 17.3 Operation 17.3.1 Conveyance control A. Outline of the operation In the vertical conveyance section, the vertical conveyance roller /1, /2 and /3 conveys paper supplied from the trays 2, 3 and 4 to the loop roller. Paper fed from the tray 1 is also conveyed to the loop roller through the vertical conveyance section.
  • Page 88 17. VERTICAL CONVEYANCE SECTION Theory of Operation Ver1.0 Aug.2005 D. Vertical conveyance of the tray 3 paper (1) Conveyance of small size paper The vertical conveyance clutch /2 (CL12) turns ON [2] a specified period of time after a print start signal [1] is sent.
  • Page 89 Theory of Operation Ver1.0 Aug.2005 17. VERTICAL CONVEYANCE SECTION (2) Conveyance of large size paper The vertical conveyance of the 1st sheet of paper is the same as the conveyance of the small size paper. How- ever, in the same manner as with the vertical conveyance clutch /1 (CL11), the vertical conveyance clutch /2 (CL12) turns OFF a specified period of time after the registration sensor (PS44) detects the leading edge of the paper and turns ON [5].

  • Page 90: Registration Section

    18. REGISTRATION SECTION Theory of Operation Ver1.0 Aug.2005 18. REGISTRATION SECTION 18.1 Composition Pre-transfer roller /Lw Pre-transfer roller /Up Centering sensor (PS66) Registration roller 57aat2c055na...

  • Page 91: Drive

    Theory of Operation Ver1.0 Aug.2005 18. REGISTRATION SECTION 18.2 Drive 18.2.1 Registration drive 57aat2c056na Registration clutch /1 (CL1) Registration roller Front Pre-transfer roller /Lw Registration motor (M5) Pre-transfer roller /Up 18.2.2 Loop roller drive 57aat2c057na Loop roller Loop motor (M6) Belt...

  • Page 92: Operation

    18. REGISTRATION SECTION Theory of Operation Ver1.0 Aug.2005 18.3 Operation 18.3.1 Loop control A. Registration path When paper supplied from the trays 1 to 4 [2], LU [1], the bypass tray [14] and ADU [5] hits against the registra- tion roller [7], a loop [12] is formed until the roller provided just in front of the registration roller on each convey- ance path turns OFF.
  • Page 93 Theory of Operation Ver1.0 Aug.2005 18. REGISTRATION SECTION B. Registration operation (1) While in the paper feed from the trays 1 to 4, LU and ADU A specified period of time after the print start signal [1] is sent, the loop motor (M6) turns ON to drive [2] the loop roller and the ADU pre-registration roller at a high process speed.

  • Page 94: Paper Mis-Centering Correction Control

    18. REGISTRATION SECTION Theory of Operation Ver1.0 Aug.2005 18.3.2 Paper mis-centering correction control To detect the mis-centering of paper after the registration, the paper leading edge sensor (PS43) and the center- ing sensor (PS66) are provided at the exit of the registration roller. PS43 detects the positional information in the sub scan direction and PS66 detects it in the main scan direction.

  • Page 95: Horizontal Conveyance Section

    Theory of Operation Ver1.0 Aug.2005 19. HORIZONTAL CONVEYANCE SECTION 19. HORIZONTAL CONVEYANCE SECTION 19.1 Composition Transfer/sepa- ration suction Thick paper support belt fan (FM3) Conveyance belt 57aat2c060na 19.2 Drive 57aat2c061na Registration motor (M5) Thick paper support belt Front Conveyance belt...

  • Page 96: Operation

    19. HORIZONTAL CONVEYANCE SECTION Theory of Operation Ver1.0 Aug.2005 19.3 Operation 19.3.1 Conveyance control A. Conveyance suction The duct [3] provided at the center of the conveyance section sucks paper passing through the conveyance section to convey it. The suction opening [4] is provided at the lower section of each conveyance belt [2] and the suction is made by the transfer/separation suction fan (FM3) [1] connected to the duct.
  • Page 97 Theory of Operation Ver1.0 Aug.2005 19. HORIZONTAL CONVEYANCE SECTION B. Duct path The duct [3] in the conveyance section [2] is connected to the transfer/separation suction fan (FM3) [1] at the lower section of the conveyance section. FM3 sucks through the duct and discharges the exhaust into the main body.

  • Page 98: Thick Paper Support Mechanism

    19. HORIZONTAL CONVEYANCE SECTION Theory of Operation Ver1.0 Aug.2005 19.3.2 Thick paper support mechanism In order to support the conveyance of the thick paper, the thick paper support belt [11] is provided. The thick paper support belt is normally [3] set at the same position in height as the conveyance belt [2]. When the set lever [5] is changed over to the thick paper mode side [4] by the manual operation, the edge of the thick paper support belt is raised.

  • Page 99: Adu

    Theory of Operation Ver1.0 Aug.2005 20. ADU 20. ADU 20.1 Composition ADU conveyance roller /1 ADU conveyance roller /2 Reverse/exit gate pre-registration roller Reverse/exit roller ADU conveyance roller /4 ADU gate ADU conveyance roller /3 ADU reverse roller 57aat2c065na...

  • Page 100: Drive

    20. ADU Theory of Operation Ver1.0 Aug.2005 20.2 Drive 20.2.1 ADU conveyance roller drive 57aat2c066na Registration motor (M5) ADU conveyance roller /1 ADU deceleration clutch (CL2) ADU conveyance roller /2 ADU conveyance clutch (CL13) ADU conveyance roller /3 Front ADU conveyance roller /4 20.2.2 ADU reverse roller drive 57aat2c067na...

  • Page 101: Adu Pre-Registration Roller Drive

    Theory of Operation Ver1.0 Aug.2005 20. ADU 20.2.3 ADU pre-registration roller drive 57aat2c068na ADU pre-registration roller Loop motor (M6) 20.2.4 Reverse/exit roller drive 57aat2c069na Reverse/exit roller Reverse/exit motor (M8) Front...

  • Page 102: Operation

    20. ADU Theory of Operation Ver1.0 Aug.2005 20.3 Operation 20.3.1 Conveyance control A. Conveyance path While in the double sided print mode, paper that has been printed on the front side passes through the reverse/ exit switching gate [5], and then it is conveyed to the ADU reverse roller [1] through the underside of the reverse/ exit gate [4], the reverse/exit roller [3] and the ADU gate [2].
  • Page 103 Theory of Operation Ver1.0 Aug.2005 20. ADU B. Pre-registration control In the double sided print mode, when the ADU pre-registration sensor (PS50) detects the leading edge of paper and turns ON [2], the ADU deceleration clutch (CL2) turns OFF a specified period of time after this to shut off the drive force of the registration motor (M5) that has been transmitted to the ADU pre-registration roller 13 and 14.

  • Page 104: Fusing Section

    21. FUSING SECTION Theory of Operation Ver1.0 Aug.2005 21. FUSING SECTION 21.1 Composition Fusing roller /Up Fusing claw /Up Fusing roller /Lw Fusing heater lamp /2 (L3) Fusing heater lamp /1 (L2) Decurler roller Cleaning web Fusing heater lamp /3 (L4) Fusing claw /Lw 57aat2e005na...

  • Page 105: Drive

    Theory of Operation Ver1.0 Aug.2005 21. FUSING SECTION 21.2 Drive 21.2.1 Fusing drive 57aat2e006na Fusing motor (M4) Fusing exit roller Fusing roller /Lw Fusing roller /Up Decurler roller Fusing input gear 21.2.2 Cleaning web drive 57aat2e007na Web solenoid (SD2) Cleaning web wind-up shaft Ratchet mechanism Cleaning web unwinding shaft Front...

  • Page 106: Reverse/Exit Switching Gate Drive

    21. FUSING SECTION Theory of Operation Ver1.0 Aug.2005 21.2.3 Reverse/exit switching gate drive 57aat2c087na Reverse/exit switching gate Reverse/exit solenoid...

  • Page 107: Operation

    Theory of Operation Ver1.0 Aug.2005 21. FUSING SECTION 21.3 Operation 21.3.1 Web solenoid control A. Cleaning web mechanism Turning ON and OFF the web solenoid (SD2) [1] rotates in the ratchet mechanism section [2]. The drive force thus generated is transmitted to the cleaning web wind-up shaft [3] through the gear to wind up the cleaning web.

  • Page 108: Fusing Temperature Control

    21. FUSING SECTION Theory of Operation Ver1.0 Aug.2005 21.3.2 Fusing temperature control The heating of the fusing roller /Up is made by the fusing heater lamp/1 (L2) and /2(L3) and the heating of the fusing roller /Lw by the heater lamp/3 (L4). The surface temperature of the fusing roller /Up is detected by the thermistors /1 (TH1) [2] and /2 (TH2) [1].

  • Page 109: Protection Against Abnormality

    Theory of Operation Ver1.0 Aug.2005 21. FUSING SECTION 21.3.3 Protection against abnormality When the temperature detected by the thermostats /3 (TS3) [1] gets to 180 ± 7°C, the AC power line to the fus- ing heater lamp/1 (L2) and /2 (L3) is cut off to turn off L2 and L3. When the temperature to detect the thermostat /4 (TS4) [2] reaches 110 ±10°C, the AC power line to the fusing heater lamp/3 (L4) is cut off to turn L4 OFF.

  • Page 110: Fusing Conveyance Mechanism

    21. FUSING SECTION Theory of Operation Ver1.0 Aug.2005 21.3.4 Fusing conveyance mechanism A. Decurler roller Paper guided by the reverse/exit switching gate [4] passes through between the decurler roller [2] and the restriction shaft [3] for decurl. 57aat2c088na Fusing exit roller Restriction shaft Decurler roller Reverse/exit switching gate...

  • Page 111: Reverse/Exit Section

    Theory of Operation Ver1.0 Aug.2005 22. REVERSE/EXIT SECTION 22. REVERSE/EXIT SECTION 22.1 Composition Reverse/exit switching gate Paper exit conveyance roller Main body paper exit roller Main body paper exit roller Fusing Reverse/exit Decurler exit roller Paper exit conveyance roller gate roller 57aat2c072na 22.2 Drive...

  • Page 112: Operation

    22. REVERSE/EXIT SECTION Theory of Operation Ver1.0 Aug.2005 22.3 Operation 22.3.1 Conveyance control A. Reverse/exit switching gate The reverse/exit switching gate is turned ON and OFF by the reverse/exit solenoid (SD7) to switch the convey- ance path for paper exited from the fusing exit roller over to either the straight paper exit or the reverse paper exit.
  • Page 113 Theory of Operation Ver1.0 Aug.2005 22. REVERSE/EXIT SECTION (2) Reverse paper exit While in the reverse paper exit and the ADU paper feed, the reverse/exit switching gate [9] is opened when the reverse/exit solenoid (SD7) turns OFF. Paper exited from the fusing exit roller [2] is conveyed to the reverse/exit gate [6] of ADU by the decurler roller [3] passing through the underside of the reverse/exit switching gate.

  • Page 114: Interface Section

    23. INTERFACE SECTION Theory of Operation Ver1.0 Aug.2005 23. INTERFACE SECTION 23.1 Composition Serial port (RS-232C) Compact flash card Serial port (RS-232C) RJ45 Ethernet connector Serial port (RS-232C) USB port (USB TypeB) 57aat2c076na 23.2 Operation 23.2.1 Interface specifications Item Specifications/mechanism Serial port (RS-232C) For service of system control board Compact flash card...

  • Page 115: Image Stabilization Control

    The following shows the operation flow of the image stabilization control when the power switch (SW2) is turned ON. However, this flow indicates an example in bizhub 750 in which the warm-up is made for 180 sec. in the prescribed environment.
  • Page 116 24. IMAGE STABILIZATION CONTROL Theory of Operation Ver1.0 Aug.2005 C. Maximum density correction (1) Purpose • According to "24.2.2 Image stabilization control flow while in the print and after completion of the print.." (2) Execution timing • After completion of the preliminary rotation of the drum D.

  • Page 117: Image Stabilization Control Flow While In The Print And After Completion Of The Print

    Theory of Operation Ver1.0 Aug.2005 24. IMAGE STABILIZATION CONTROL 24.2.2 Image stabilization control flow while in the print and after completion of the print. The following shows the flow of the image stabilization controls taken while in the print and after completion of the print.
  • Page 118 24. IMAGE STABILIZATION CONTROL Theory of Operation Ver1.0 Aug.2005 B. Black belt creation control (1) Purpose To stabilize the load on the cleaning blade, coat the entire drum image area with toner before cleaning the clean- ing blade. (2) Method Create a black belt of 0.5 mm in width on the drum corresponding to the position about 20 mm from the leading edge of the preceding paper.
  • Page 119 Theory of Operation Ver1.0 Aug.2005 24. IMAGE STABILIZATION CONTROL Gamma correction control (1) Purpose To maintain the image at a fixed gradation without being negatively affected by the environmental condition and the number of prints. (2) Method • Create multiple toner patches on the drum while changing the laser PWM. At this time, create patches with the number of rotations of the developing roller decided at the maximum density control.

  • Page 120: Image Processing

    25. IMAGE PROCESSING Theory of Operation Ver1.0 Aug.2005 25. IMAGE PROCESSING 25.1 Image processing in the scanner section A. Shading correction B. AE correction C. Area discrimination D. Brightness/density conversion E. Filter /magnification and contraction F. Density gamma (conversion) G. Tilt adjustment H.

  • Page 121: Ae Processing

    Theory of Operation Ver1.0 Aug.2005 25. IMAGE PROCESSING 25.1.2 AE processing The AE control selects automatically a density suitable for the original density and the copy is made properly. A. Sampling area (1) While in the platen mode • While in the normal copy 57aat2c077na 30 mm 10 mm...

  • Page 122: Area Discrimination

    25. IMAGE PROCESSING Theory of Operation Ver1.0 Aug.2005 25.1.3 Area discrimination To make a copy of the original under the appropriate condition (to make an appropriate filter processing), check the read section to see if it is a character or a dot picture, and use the results in the image processing section at the later stage.

  • Page 123: Image Processing In The Write Section

    Theory of Operation Ver1.0 Aug.2005 25. IMAGE PROCESSING 25.2 Image processing in the write section A. Elongation/rotation B. 1dotPWM C. Frequency conversion 25.2.1 Elongation/rotation When outputting images from the memory, elongate the compressed data to restore them to their original state. Rotate the image in the direction of 90 degrees or 180 degrees as required.

  • Page 124: Others

    26. OTHERS Theory of Operation Ver1.0 Aug.2005 26. OTHERS 26.1 Fan control 26.1.1 Composition [10] [11] [12] [13] [14] [15] 57aat2e012na Developing suction fan (FM4) Cleaner cooling fan (FM5) Developing cooling fan (FM12) [10] Polygon cooling fan (FM2) Power supply cooling fan /1 (FM16) [11] Scanner cooling fan (FM9) Power supply cooling fan /2 (FM15)

  • Page 125: Operation

    Theory of Operation Ver1.0 Aug.2005 26. OTHERS 26.1.2 Operation A. Cooling fan /1 (FM1) control (1) Purpose To exhaust around the drum and the fusing section. (2) ON timing • While in the warm-up, turns ON (rotates at a low speed) in accord with the drum motor (M2). •...
  • Page 126 26. OTHERS Theory of Operation Ver1.0 Aug.2005 E. Cleaner cooling fan (FM5) control (1) Purpose To cool down around the cleaning section. (2) ON timing Turns ON a specified period of time after the power switch (SW2) turns ON. (3) OFF timing Not to turn OFF until the power switch (SW2) is turned OFF.
  • Page 127 Theory of Operation Ver1.0 Aug.2005 26. OTHERS (3) OFF timing Turns OFF in accord with the turn OFF of the exposure lamp (L1). ADU cooling fan (FM10) control (1) Purpose To cool down around the ADU reverse motor (M9) and the ADU reverse section. (2) ON timing Turns ON in accord with the turn ON of the ADU reverse motor (M9).
  • Page 128 26. OTHERS Theory of Operation Ver1.0 Aug.2005 N. CPU cooling fan (FM20) control (1) Purpose To cool down the system control board (SCB) with suction. (2) ON timing • While in the print, rotates at a high speed. • While in the idle, and while in the low power mode and the normal sleep mode, changes over between the high speed rotation and the low speed rotation according to the temperature detected by the CPU.

  • Page 129: Counter Control

    Theory of Operation Ver1.0 Aug.2005 26. OTHERS 26.2 Counter control 26.2.1 Composition PRCB LCDB CNT1 CNT2 PS37 57aat2c080na 26.2.2 Operation A. Paper exit counter Item Specifications/mechanism • Total counter (CNT1) Displays the cumulative number of prints in all print modes. •...
  • Page 130 26. OTHERS Theory of Operation Ver1.0 Aug.2005 B. Coin vendor The following shows the specifications of the connecting connector. Connector Pin No. Signal name Description Output timing Type of signal Paper feed Output from the start L output while in Open collector output motor (M1) button being turned...

  • Page 131: Parts That Operate When The Power Switch Is Turned On

    Theory of Operation Ver1.0 Aug.2005 26. OTHERS 26.3 Parts that operate when the power switch is turned ON 26.3.1 Parts that operate when the power cord is plugged into the power outlet. A. Composition CBR1 Coil/2 DCPS1 CBR2 57aat2e013na B. Operation When the dehumidification heater switch (SW3) is turned ON, when the power cord is plugged into the power outlet, the dehumidification heaters /1 (HTR1) and /2 (HTR2), and the dehumidification heater (HTR101) of LU are turned ON.

  • Page 132: Parts That Operate When The Main Power Switch (Sw1) Is Turned On

    26. OTHERS Theory of Operation Ver1.0 Aug.2005 26.3.2 Parts that operate when the main power switch (SW1) is turned ON A. Composition Coil/1 EU only CBR1 Coil/2 DCPS1 CBR2 12VDC PRCB DCPS2 5VDC 57aat2e014na B. Operation Turning on the main power switch (SW1) supplies the AC power source to the DC power sources /1 (DCPS1) and /2 (DCPS2).

  • Page 133: Parts That Operate When The Power Switch (Sw2) Is Turned On

    Theory of Operation Ver1.0 Aug.2005 26. OTHERS 26.3.3 Parts that operate when the power switch (SW2) is turned ON A. Composition DCPS1 CBR1 5VDC 12VDC 24VDC Coil/2 CBR2 PRCB 57aat2e015na B. Operation When the power switch (SW2) is turned ON with the main power switch (SW1) ON, the DC power source /1 (DCPS1) supplies the 24V DC power source system for the drive of various types of load in addition to the power source systems that have been supplied so far.
  • Page 134 26. OTHERS Theory of Operation Ver1.0 Aug.2005 Blank page...

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