Sharp AL-840 manual

SER VICE MANU AL CODE: 00ZA L840/ /B1E BASIC MANUAL DIGIT AL COPIER MODE L AL-800/840 SHARP CORPORATION This document has been published to be used for after sales service only. The contents are subject to change without notice. Parts marked with " ! " is important for maintaining the safety of the set. Be sure to replace these parts with[...]

[1] OPERATING PRINCIPLE 1. B l oc k di ag ra m CCD CPU ASIC MEMORY MEMORY ICU PWB ASIC HOST(PC) KEY AC POWER Control signal, detection signal, drive signal, control data line Image data signal line Image (light) Power line Paper path line OPERATION PWB LAMP (LED) MAIN MOTOR PRINT PWB SCANNER HOME POSITION SENSOR COPY LAMP LIGHT QUANTITY SENSOR MIRR[...]

Scanner (read) section In this section, the copy lamp (cathode ray tube, Xenon lamp) radiates light onto a document, and the reflected light is detected by the image sensor (CCD element) to convert into electrical signals (analog signals), which are sent to the MCU PWB. MCU (ICU) PWB The image data from the scanner (reading) section are converted i[...]

2. Out line o f ope rations A. Paper path and imaging Paper is fed, transported, and discharged through the path indicated with the arrow in the figure below. 1) Paper feed (Paper on the paper tray is fed to the transfer section by the paper feed roller.) 2) Image transfer (The toner image on the photoconductor is trans- ferred onto the paper by th[...]

(2) Printer mode P1) Print data (compressed data) are sent from the host. (Image data (Data 1 – 8) P2) Print data are developed by the ASIC and the line memory and converted into the full dot image data and sent to the data select section. (Image data)(VIDEO) P3) The data are sent through the data select section to the scan- ner (writing) section[...]

3. Oper at ions of each s ection A. Paper feed, paper transport section (1) Outline The paper feed tray contains about 200 (250) sheets of paper. The paper is passed to the transfer section by the paper feed roller. The paper feed operation is controlled by the paper feed roller clutch and the paper feed roller clutch solenoid. The paper feed clutc[...]

No. Parts Note Code Signal name Name Type Function/operation Active condition 1 PE SENSOR PEMP IN Paper empty detector Photo transmission sensor Detects paper on the paper tray. LOW (0V) when paper is detected. 2 Paper guide Adjust the paper width. 3 Paper feed tray Sets the print paper. (Capacity: XXX sheets) 4 Paper release lever Put this lever s[...]

(3) Operation a. Block diagram b. Operation * The main motor is a 4-phase stepping motor of 2-phase excite- ment bipolar system, which serves as the drive source of the paper feed and transport system. * The pickup solenoid operates on 24V and turns ON/OFF paper feed operation. * The following sensors are used. Paper empty sensor (transmission phot[...]

(Paper release operation) The lock lever arm is always pressed onto the paper release lever by th e sp r in g. When th e pa pe r re lea se leve r is p ul led to war d y ou , th e lock lever arm is brought into contact with the lower frame so that the paper pressure plate is fixed at the paper release position. Under this condition, a clearance is p[...]

The paper feed roller is of circular form, and double paper feed is prevented by the separate sheet. The paper feed clutch lever is provided to prevent the paper feed roller from rotating reversely. When paper feed is not performed, the paper feed clutch lever is engaged with the paper feed roller boss gear. When removing paper for paper replacemen[...]

(2) Major parts No. Parts Note Code Signal name Name Type Function/operation Active condition 1 Scanner lamp control PWB Drives the scanner lamp. Maintains the lamp light quantity at a constant level. 2 Scanner drive wire Transmits the scanner motor power to the scanner unit. 3 Scanner motor Drives the scanner unit. 4 MHPS MHPS Scanner home positio[...]

(3) Operation a. Wiring diagram * Copy lamp A cathode ray tube (Xenon lamp) is used as the light source for reading images. To maintain the lamp light quantity at constant level, the following operations are performed. The copy lamp light quantity sensor is provided in the scanner unit to detect the copy lamp light quantity. The copy lamp drive vol[...]

* 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 se[...]

No. Parts Note Code Signal name Name Type Function/operation Active condition 1 SYNC SYNC IN Laser beam sensor Bin diode Detects the laser beam position. By this signal the left image print start position is controlled. LOW (0V) when laser beam is detected. 2 No. 1 mirror 3 No. 3 mirror Leads the laser beam to the OPC drum. 4 Second cylindrical len[...]

The scanning mirror is a 6-surface mirror. Six lines are printed for one rotation of the scanning motor. Laser beams reflected by the scan- ning mirror are passed to the curved mirror by the No. 1 reflection mirror. Before reaching the curved mirror, the laser beams enter the laser beam sensor on the start position detection PWB to make horizontal [...]

(2) Image forming process diagram The operation of this section are composed of the six processes: charging, exposure, development, transfer, separation, and discharg- ing. An OPC drum is used as the photocoductor drum. Toner is of one-component. For charging, the rotation brush is used. For trans- fer, the roller is used and virtually no generatio[...]

(3) Major parts a. Photoconductor section No. Parts Note Name Type Function/operation 1 OPC drum OPC Forms latent electrostatic images. 2 OPC drum earth electrode Connects the OPC drum aluminum layer and the earth (high voltage PWB). 3 Main charger electrode Connects the main charger output (high voltage PWB) and the main charger brush. 4 Discharge[...]

b. Development section No. Parts Note Name Type Function/operation 1 Developing roller Attaches toner to the latent electrostatic images on the OPC drum to convert it into a visible image. 2 Developing doctor Controls toner quantity on the developing roller and charges toner. 3 Developing bias electrode Connects the developing roller and the bias v[...]

c. Transfer/separation section No. Parts Note Name Function/operation 1 Transfer roller Transfers toner images on the OPC drum onto the paper. 2 Transfer roller electrode Connects the transfer roller and the transfer voltage output (high voltage PWB). 3 Pressure spring Applies pressure to the transfer roller, paper, and the OPC drum to improve tran[...]

(4) System diagram (5) Operation a. Wiring diagram DC-200V DC-310V DC+500V DC-850V AC600V(P-P) DC +3.5KV AC600V(P-P) DC – 850V DC +200V DC – 310V – 310V/+ 200V selection MCU PWB Scanning mirror Laser beam Laser unit No. 1 - 4 mirror Main charger brush Discharge brush Separation electrode Photoconductor drum Transfer charger roller Developing [...]

b. Major parts functions and operations 1 Developing roller 5 Toner seal 9 Discharge brush 2 Doctor 6 Transfer charger roller 10 Main charger brush 3 Toner stirring plate 7 Separation electrode 11 Toner seal 4 Toner supply roller 8 Phot conductor drum 12 Discharge (Earth) sheet <1> Photoconductor drum unit The photoconductor surface is charge[...]

c. Actual image forming process Step 1 (Cleaning, charging): Residual toner on the OPC drum is stirred and negative charges are dis- tributed evenly on the OPC drum. (The OPC drum is evenly charged.) The main charger brush is of roller shape and is rotating. The main charger brush stirrs residual toner and paper dust on the OPC drum. At the same ti[...]

Step 3 (Development): Toner is attached to the latent electrostatic images formed on the OPC drum. Toner enters between the developing roller and the doctor, and a thin layer of toner (a certain fixed amount) is formed on the developing roller by a pressure applied to the doctor. Toner is negatively charged by friction when passing between the deve[...]

The positive charges are attracted to the OPC drum which is nega- tively charged, and put on the paper transported between the transfer roller and the OPC drum. The paper, therefore, is charged positively. The negative charged toner on the OPC drum is attracted to the paper which is positively charged and visible images of toner are transferred ont[...]

d. OPC drum surface potential <1> OPC drum surface potential shift in printing <2> OPC drum surface potential and developing bias voltage during developing -310V -850V OPC drum surface potential (-V) Charging/ cleaning Laser beams Dark area potential Toner attraction potential Light area potential Exposure Residual toner collection/ Dev[...]

E. Fusing/paper exit section (1) Outline Toner attracted to the paper in the transfer section is fused by heat and pressure of the heat roller. The heat roller is of thin aluminum roller which is high heat conductivity, minimizing the warm up time. The heat roller surface temperature is detected by the fusing temperature sensor to maintain the fusi[...]

(3) Operation a. Wiring diagram b. Operation The heater lamp ON/OFF is controlled by the detection signal (volt- age value) from the thermistor to maintain the heat roller surface temperature at the optimum level. The heat roller surface temperature is controlled to 160/155 ˚C in the print mode and to 80 ˚C in the pre-heat mode. As a protective m[...]

F. Drive section (1) Outline The main motor drives the paper feed section, the transport section, the image process section, and the fusing section . The main motor drive circuit is built in the high voltage power PWB. (2) Major parts No. Parts Note Code Name Type Function, operation 1 MM Main motor Stepping motor (+24V) Drives the paper feed secti[...]

G. Electrical section (1) Block diagram a. Major sections operations and functions MCU (PCU) PWB The CPU controls the engine, and the ASIC performs image process. Image data (analog signals) from the scanner (reading) section are converted into digital signals by the A/D convertor and image process (area separation, filter process, gamma correction[...]

ICU PWB Print data from the host (PC) are developed by the ASIC and the line memory (DRAM) to converted into full dot image data, which are then outputted to the data select section in the MCU PWB. The machine status data from the MCU PWB are outputted tot he host (PC). In addition. the ASIC controls the parallel I/F. Operation PWB Status data from[...]

q COPYRIGHT  1998 BY SHARP CORPORATION All rights reserved. Printed in Japan. No part of this publication may be reproduced, stored in a retrieval system, or transmitted. In any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission of the publisher. SHARP CORPORATION Printing Reprog[...]