Patent ID: 7365764
Filing Date: 2008-04-29
Classification: G02B,H04N

Abstract:
1. A scanning optical apparatus, comprising; a light source; a deflecting element for deflecting and scanning a beam emitted from said light source; an imaging optical element for imaging the beam deflected by a deflection surface of said deflecting element as a spot image on a scanned surface; a sensor for synchronous detection, for detecting the beam deflected by the deflection surface of said deflecting element as a synchronization signal for determining an image writing beginning position of the beam on the scanned surface; and an optical element for synchronous detection, arranged in an optical path between the deflecting surface of said deflecting element and said sensor for synchronous detection, wherein the beam deflected by the deflection surface of said deflecting element is directed to said sensor for synchronous detection without passing through said imaging optical element, wherein an optical axis of said optical element for synchronous detection and a principal ray of the beam deflected by the deflection surface of said deflecting element in entering said sensor for synchronous detection are coincident with each other, and wherein an irradiated position detecting means is arranged on only one side of an image writing end position of the beam, taking the optical axis of said imaging optical element as a center, so that with respect to an irradiated position of the beam deflected by the deflection surface of said deflecting element and imaged by said imaging optical element on the scanned surface, said irradiated position detecting means detects the irradiated position of the beam on the scanned surface in a main scanning direction; and wherein a correction to magnification of the imaged beam in the main scanning direction is determined based on a position signal from said irradiation position detecting means.