CX PARTS CATALOG

DIAGRAM 400
Laser Scanning Unit

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Important Note

The laser scanning assembly contains a semiconductor laser, which produces a wide beam that becomes focused by a collimating lens. The resultant narrow beam is directed at a rotating six-sided mirror, mounted directly to the scanning motor. The scanner housing contains a large glass prism and a flat mirror to reflect the moving beam at constant size and shape onto the OPC drum located inside the toner cartridge. Resolution in the horizontal direction is determined by the embedded formatter or external video controller, which has absolute control of when the laser beam is turned on and off along each scan line.

Since the paper and drum always rotate at a fixed 8 ppm speed, the RPM rate of the scanning motor determines the vertical distance between scan lines and, therefore, vertical resolution. The faster the scanner motor turns, the more scan lines are created and the higher the resolution will be. Consequently, the only difference among the 240, 300, 400, and 415 dpi versions is the scanner motor.

The voltage to the laser must be adjusted with a trim pot on the DC controller to maintain the proper print intensity. Too high a voltage will destroy the semiconductor laser, too low a voltage will produce light print. A special tool exists (Part Number TKN-0198) to measure the laser beam intensity. Some other useful, related tools are also available: a Laser Driver tool (RY9-0002-000); and a Laser Shorting Connector (RY9-0003-000).

When changing resolutions, the DC controller must also be changed, as it contains a time base for measuring the RPM rate of the scanner motor. If the scanner and DC controller are mismatched, the DC controller will turn off the scanner motor and shut down the printer.

SCANNERS, DC CONTROLLERS, AND LASER UNITS MUST BE MATCHED, CALIBRATED AND ALIGNED.

If you need to change a scanner or a laser unit or a DC controller and do not have the special knowledge and/or tools for adjusting the laser beam intensity, we recommend ordering these three items together: a DC controller, scanner and laser unit combined and pre-adjusted by The Printer Works. Canon did not create or publish part numbers for the laser and scanner combined into a whole assembly. Instead, only the individual part numbers are used. Our technicians can explain the installation and mechanical adjustment procedures. Alternatively, just pack up the printer and ship it to us and we will be happy to make sure that everything is installed and tuned to the correct specifications.

All CX and CXD printers use the same scanner assemblies. Early versions were made of metal, but most were molded in plastic. All Apple, Canon, HP, QMS and most other OEMs used the 300 dpi scanner motor. Federal Express used a 415 dpi motor, which can be modified by companies like The Printer Works to turn at the 300 dpi rate for compatibility with standard video controllers, such as the QMS JetScript.