Patent ID: 7312808
Filing Date: 2007-12-25
Classification: G02B,G03G

Abstract:
1. An image forming apparatus comprising: a photosensitive member; a scanning unit that exposes and scans a surface of the photosensitive member by emitting a light beam, the scanning unit including a unit frame that has a base section having an opening and an outer peripheral wall surrounding a rim of the base section; a deflector that is disposed on an upper surface side of the base section and deflects the light beam toward the outer peripheral wall; a first reflection optical element that is disposed with the opening being interposed between the first reflection optical element and the deflector and reflects the light beam, which has been deflected by the deflector and travels toward the outer peripheral wall, toward a position below the base section; and a second reflection optical element that is disposed on a lower surface side of the base section and reflects the light beam, which travels after having been reflected by the first reflection optical element and passed through the opening, toward the photosensitive member; wherein an angle between the light beam entering the first reflection optical element and the light beam reflected from the first reflection optical element toward the second reflection optical element is an acute angle; and a relationship of a<b and another relationship of c<b are satisfied, given that an optical path length from a reflection surface of the deflector to a reflection surface of the first reflection optical element is taken as “a”; another optical path length from the reflection surface of the first reflection optical element to a reflection surface of the second reflection optical element is taken as “b”; and still another optical path length from the reflection surface of the second reflection optical element to the surface of the photosensitive member is taken as “c.”