ROTARY POLYGON MIRROR DRIVING DEVICE

摘要

PURPOSE:To solve the deterioration of rotating accuracy or the accuracy of a bearing and to make a device this and inexpensive as for the rotary polygon mirror driving device used for a laser beam printer(LBP). CONSTITUTION:The device is provided with a rotor 13 having a rotary shaft 1 and a magnet 3 and a rotary polygon mirror 2 fixed to the rotor 13 and constituted of a bracket 16 consisting of a base plate 11 provided to be faced to the magnet 3 and the collar 15 of a bearing holding part which is outserted to the base plate 11 and which consists of resin. Besides, the collar 15 is constituted of a first cylindrical part 15a which is thinly formed on the rotor side and a second cylindrical part 15b which is thicker than the first cylindrical part 15a on the base plate side. Then, the bearing 10 supporting pivotally the shaft 1 is engaged and fixed t the first cylindrical part 15a of the collar 15. By engaging and fixing a sleeve to the thin part of the collar 15, the device can be assembled and maintained with hardly changing the accuracy of the inner diameter of the sleeve. Specially, such an effect is remarkable as for the sleeve such as the fluid bearing whose inner diameter is changed large and which affects loss or rigidity.