| 摘要 |
PROBLEM TO BE SOLVED: To easily exchange a polygon mirror even in such constitution that the polygon mirror is pressed and fixed on a mirror placing surface by a mirror pressing member. SOLUTION: In this device 1, in the case of detaching the polygon mirror 30 after the mirror 30 is pressed and fixed on a rotor by the mirror pressing member 50, the member 50 is fit in the engaging groove of the cylinder part 250 of a rotor main body 25, so that the mirror 30 is not easily detached. A narrow cutting scheduled part 506 is previously formed on the member 50. In the cutting scheduled part 506, the ring part 500 of the member 50 floats from the upper end face of the mirror 30 and does not come in contact with the cylinder part 250, whereby the member 50 is easily cut by inserting a nipper in the part 506. |
