PURPOSE: To provide attaching structure for a polygon mirror which does not exert an adverse influence on jitter characteristic, where balance is not deteriorated with time and which is easily worked and excellent in stability.
CONSTITUTION: In the polygon mirror 3 attaching structure for fixing the polygon mirror 3 on a rotating body, the polygon mirror 3 having an annular groove 4 whose cross section is rectangular is placed at a position being a specified radius from the center of rotation on the upper surface of a mirror bearing surface formed on the outer periphery of the rotating body. By providing a flat ring-like locking member 5 equipped with a projection 5b formed to be conical or semispherical downward and having plural pawls 5a on the outer periphery part, engaging the projection 5b of the locking member 5 with the annular groove 4 of the polygon mirror 3, and pressing the upper end on the inner periphery of the groove in a point contact state by the projection 5b, the polygon mirror 3 is positionally fixed.
HASHIMOTO KAZUNORI
MARUYAMA TORU
