| 摘要 |
PROBLEM TO BE SOLVED: To reduce the number of parts and to minituarize a unit by constituting a cover for protecting a laser scanning optical unit so as to be commonly used as a heat radiating plate for cooling a polygon motor control substrate IC. SOLUTION: A laser beam passing through a toroidal lens 2 is reflected by a polygon mirror 3 which is rotation-driven by a polygon motor 4 and scanned. The laser beam reflected by the polygon mirror 3 is converged by an Fθlens 5 and focused on a photosensitive material. A laser light source 1, the toroidal lens 2, the polygon motor 4 and the Fθlens 5 are held by a chassis 6. Then, the control substrate 7a controlling the polygon motor 4 is placed at the outside of the chassis 6, a sheet metal cover 8a for protecting the chassis 6 is adhesively fitted to IC9 of the control substrate 7a and the cover 8a and the control substrate 7a are fixed by a screw. The cover 8a also plays a role for cooling IC9 of the control substrate 7a.
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