The present invention relates to a drive motor for rotating a multi-faceted mirror, and more particularly, to a drive motor for rotating a multi-faceted mirror, which is used to change the path of a laser beam in a laser printer or a laser scanner.
An optical data processing device such as a laser printer or a laser scanner has been developed to process optical data on a large scale. The optical data processing device for printing or scanning a large amount of data at high speed is comprised of a laser 1 with excellent convergence, a high-speed beam deflector 2, rotating a multi-faceted mirror 3, and a drive motor 4 for rotating the multi-faceted mirror 3, as shown in FIG. 1.
FIG. 2 is a simplified view of a bearing portion of a conventional drive motor for rotating a multi-faceted mirror. As shown in FIG. 2, a pair of upper and lower ball bearings 40 are disposed between a bearing housing 10 and a shaft 30 fixed to a rotor 41 of the motor. The reference numeral 11 denotes a bearing cover.
There are no problems during printing or scanning with drive motors having ball bearings 40 installed therein, as long as the printer or scanner operates at a low speed. However, significant problems occur when the printer or scanner operates at a high speed. That is, if printing or scanning is performed by rotating the multi-faceted mirror 3 at above speeds of 20,000 RPM, there is significant shaking and noise in the ball bearings 40, which are contact-type bearings.