| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical scanner capable of achieving miniaturization without deteriorating layout properties or scanning accuracy. <P>SOLUTION: A polygon mirror 2104 has a tetrahedral mirror as a rotary polyhedron in which an angle formed between a surface 1 and a surface 2 is 90°, an angle formed between a surface 2 and a surface 3 is 89.6°, an angle formed between a surface 3 and a surface 4 is 90.4° and an angle formed between a surface 4 and a surface 1 is 90°. In this case, an optical scanner can securely identify a deflection and reflection face on which light for scanning an effective scanning region of photoreceptor drum is reflected. Consequently, even if a synchronization detection sensor is not always disposed corresponding to all of the photoreceptor drums, write-in start timing to a photoreceptor drum in which a synchronization detection sensor is not disposed can be accurately determined. <P>COPYRIGHT: (C)2013,JPO&INPIT |
