| 摘要 |
PROBLEM TO BE SOLVED: To reduce the thickness of a closed vessel without reducing its natural vibration to improve heat dissipation property by using magnesium as a constituting material to form the closed vessel, where a polygon mirror, a motor, and a driving circuit are sealed, by an extrusion forming method and using a material having a high heat conductivity. SOLUTION: A polygon mirror unit 6 integrated with a substrate is positioned in a prescribed position of an optical housing 2 by a positioning member 12. A unit chamber 4 forms a closed space by a part of the enclosure of the optical housing 2, a unit chamber cover 8, and a window glass 10. Since the unit chamber 4 is sealed up and cannot let the heat directly get away to the outside by the convection of air, the heat must be transmitted to their outer wall surfaces by heat conduction and gets away from these surfaces to the outside thereafter. Then an article molded by injection of magnesium is used as the optical housing 2, and the heat dissipation property is improved because its thickness can be made thinner than the minimum thickness obtained by using aluminum. |
