| 摘要 |
PROBLEM TO BE SOLVED: To prevent movement caused by a thermal expansion difference and the occurrence of vibration caused by the movement by forming a rotary shaft, a polygon mirror, a mirror fixing member fixing the polygon mirror and a rotating driving magnet of aluminum allay. SOLUTION: A hollow rotary shaft 5, the polygon mirror 7 and the mirror fixing member 8 out of members forming a rotary body 10 are formed of the aluminum alloy. Also, the rotating driving magnet 9 out of the members forming the rotary body 10 is formed of an aluminium manganese magnet. Thus, temperature at the inside of a housing space 3 becomes high to >=90 deg.C caused by the heat generation of a motor part and the temperature rising of the inside of a copying machine when the rotary body 10 rotates. Though the hollow rotary shaft 5, the polygon mirror 7, the mirror fixing member 8 and the rotating driving magnet 9 or the like forming the rotary body 10 are respectively thermally expanded, the thermal expansion difference is not caused at the respective members 5, 7, 8 and 9 at the time of high temperature or is made very small even in the case that it is caused. |
