Sharp Digital Copier, AL-840, AL-800 service manual Scanner writing section, Block diagram

Page 13

*CCD unit

Images (light) is converted into an electrical signal (analog signal) by the CCD.

The image signal read by the CCD is converted into a digital signal b the A/D convertor in the MCU PWB and outputted to the ASIC, where the image is processed.

*Scanner motor

The scanner unit is driven by the scanner drive motor.

*Scanner home position sensor

The scanner home position sensor senses the scanner position. The copy image position control is performed by the sensing timing of this sensor.

*Zooming

Zooming is performed by changing the copy magnification ratio in the sub scanning direction or changing the scanning speed.

The copy magnification ratio in the main scanning direction is changed by the software in the ASIC.

C. Scanner (writing) section

(1) Outline

In this section, the dot image data sent from the MCU PWB are converted into laser beams (ON/OFF), which are scanned to form latent electrostatic images on the OPC drum. It is composed of the laser beam generating section (where dot image data signals are converted into laser beams (ON/OFF)), the laser beam correction section, the laser beam scanning section, and the laser beam detect- ing section. The major parts and their functions are described in the following.

(2) Block diagram

Scanning motor drive signal (PMD, PMCLK)

MCU

VIDEO

Laser diode

Laser

Collimator

No. 1

cylinder

(PCU)

 

control circuit

diode

lens

 

lens

 

 

 

 

 

SYNC

Laser beam

No. 2

No. 1

Motor

reflection mirror

reflection

 

 

sensor

mirror

 

 

(curved mirror)

mirror

 

 

 

 

Drum

No. 2 cylinder lens

No. 3 reflection mirror

Signal

Laser beam

(3) Major parts

2)

1) SYNC

3)

8)

7)

4)

6)5)

1 – 12

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Contents Model AL-800/840 Operating Principle High voltage power PWB Fusing/paper exit sectionPower PWB Scanner read sectionPaper path and imaging Copy modeImage process and data flow Printer mode Data Flow DiagramOutline Paper feed, paper transport sectionMajor parts PUSPUS PE Sensor PempPIN Sensor Paper SizeOperation Paper release operation Scanner reading section CCD CCD OUT MhpsCCD SensorAsic IC8 Mcupcu PWB Wiring diagramScanner writing section Block diagramMcupcu PWB LSU PWB SyncICU PWB Image process section Image forming process diagram OPC Photoconductor sectionDevelopment section Transfer/separation section CPU IC5 System diagramDeveloping unit Photoconductor drum unitTransfer charger roller Separation electrodeActual image forming process Paper Transfer roller Residual toner OPC drum OPC drum surface potential OPC drum surface potential and developing biasModel Fusing/paper exit sectionRTH Hlon HLL AC PowerComp AMP CN2Drive section Wiring diagramAsic CPU IC5 MEN MMT0 MMT1Major sections operations and functions Electrical sectionPower PWB High voltage power PWBCopy lamp control PWB Operation PWB Copyright 1998 by Sharp Corporation
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