| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a scanning optical device forming an image of high accuracy by detecting out-of-focus information in a main scanning direction of light imaged on a surface to be scanned at high accuracy outside an image forming range. <P>SOLUTION: The scanning optical system includes a writing start position detection means 8 for detecting a writing start position for image information by using light flux from a light source means 1 deflected by a deflection means 5 and a third optical system 91A for detecting light collection position for light flux making incidence on the surface to be scanned by using the light flux making incidence outside the image forming range of the surface to be scanned. In this case, the third optical system 91A includes a light flux restriction means 9a for restricting the incident light flux, a focusing optical element 91b and an optical detection section 9c. The light source means 1 carries out light emission at least at two timings among the timings for the deflected light flux making incidence on the focusing optical element 91b by driving the deflection means 5. The light detection section 9c detects the incident positions of the light flux making incidence when the light source means 1 emits light at least at two timings and the derives focusing position of the light flux making incidence on the surface to be scanned. <P>COPYRIGHT: (C)2012,JPO&INPIT |
