Patent ID: 8723902

Claim:
A polygon motor unit to be mounted in a predetermined housing, the housing having a plurality of lenses arranged therein comprising: a polygon mirror which is driven and rotated and deflects light irradiated to the circumferential surface thereof to scan a predetermined target; a polygon motor which includes a shaft portion and rotates the polygon mirror; a plate-shaped board which includes a first surface and a second surface opposite to the first surface, the polygon mirror and the polygon motor being mounted on the first surface; a plate-shaped thermally conductive member which includes a positioning portion for setting a reference position with respect to the housing, a third surface facing the second surface and a projection projecting from the third surface toward the second surface and configured to position the board with respect to the reference position by coming into contact with the second surface; and an elastic member which is made of a thermally conductive material and arranged between the second surface and the third surface and comes into contact with the second surface and the third surface with a restoring force, wherein the elastic member is arranged between the second surface and the third surface near a position on the board where the shaft portion is arranged; the shaft portion penetrates the board from the first surface to the second surface and projects toward the third surface; the thermally conductive member includes a bearing hole formed in the third surface to face the shaft portion; and the elastic member is arranged between the second surface and the third surface to surround the bearing hole.