Scanner (reading) section

Scanner (writing) section

Fusing/paper exit section

Paper feed section

Image process section

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 into digital signals and subject to image process (correction, etc.), and converted into dot image data and outputted to the scanner (writing) section.

During printing, the dot image data from the ICU PWB are outputted to the scanner (writing) section directly. The engine status data are outputted to the ICU PWB.

The loads (motor, solenoid, etc.) are controlled according to the sen- sor/detector signal.

The above operation is performed by the CPU, ASIC, and memory.

The operations of this section are composed of five processes; ex- posure, development, transfer, separation, and discharge.

The OPC drum is used as the photoconductor drum, and one-com- ponent toner is employed.

For charging, the rotation brush is employed. For transfer, the roller is employed to eliminate ozone generation. In addition, t is compact.

The high voltage required in this section is supplied by the high voltage PWB.

Fusing/paper exit section

Toner is fused to the paper in the fusing/paper exit section using heat and pressure.

The heat roller surface temperature is detected by the fusing temperature sensor to maintain the constant fusing temperature (155 ˚C).

The heater lamp is driven by the power PWB unit.

ICU PWB

Print data (compressed data) sent from the host are developed and converted into dot image data and outputted to the scanner (writing) section. The engine status data sent from the MCU (PCU) PWB are outputted to the host (PC).

Scanner (writing) section

In this section, the dot image data sent from the MCU PWB are converted into laser beams (ON/OFF), which is scanned to form latent electrostatic images on the OPC drum.

Paper feed section

The paper feed roller feeds paper to the transfer section.

The paper feed operation is controlled by the paper fed roller clutch and the paper feed roller clutch solenoid.

Image process

This section is composed of the photoconductor section, the develop- ing section, and the transfer/separation section. The images formed by laser beams in the scanner (writing) section are formed into latent electrostatic images on the photoconductor and converted into visible images by toner development.

Operation PWB

The operation PWB displays various information and supplied the key operation signals to the MCU (PCU) PWB.

High voltage power PWB

The high voltage power PWB outputs the high voltage for the main charger, the developing bias, and the transfer charger. In addition, the main motor drive circuit is built into the PWB.

Main motor.

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 into the high voltage power PWB.

Copy lamp control PWB

The copy lamp light quantity is controlled to provide necessary light quantity even though the conditions of the scanner (reading) section are changed.

The copy lamp drive voltage is controlled by the output level of the light quantity sensor in the scanner (reading) section.

Power PWB

The power PWB outputs the DC power voltages (+24V, +5V, +3.3V, +12V), and drives the heater lamp.

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Sharp AL-840 Scanner read section, Fusing/paper exit section, Scanner writing section, Paper feed section, Image process