Patent ID: 7079297

Claim:
An optical scanning device for deflecting incident light modulated in accordance with video data and scanning by the incident light over a scanned surface to form an image, said optical scanning device comprising: a scanning means which is rotated in a forward rotation direction and a reverse rotation direction and for deflecting said incident light in accordance with the forward rotation and the reverse rotation; and a correcting means for matching the position of the image formed by scanning by said incident light deflected in accordance with said forward rotation on said scanned surface and the position of the image formed by scanning by said incident light deflected in accordance with said reverse rotation on said scanned surface, wherein said correcting means comprises: an angle detecting means for detecting a rotation angle of said scanning means, an angle data storing means for storing a predetermined one frame's worth of angle data in a memory at each time, with respect to a reference signal instructing said rotation, detected by said angle detecting means, and a modulation controlling means for calculating a time with respect to said reference signal where said scanning means becomes a predetermined angle from said stored predetermined one frame's worth of angle data at each time and outputs a modulation instruction in accordance with said video data at the time where said predetermined angle is reached, wherein said correcting means further comprises: a phase delay storing means for storing an amount of delay of phase required until obtaining angle data from said angle detecting means, and a correcting means for replacing one frame's worth of angle data of each time detected by said angle detecting means with said one frame's worth of angle data of a time after a time in accordance with said amount of phase delay has elapsed; and wherein said correcting means further comprises: a light position measuring means, arranged detachably in a predetermined direction corresponding to a predetermined rotation angle of said scanning means, for detecting light rays deflected by said scanning means, a first angle measuring means for setting an angle so that light rays deflected by said scanning means strike said light position measuring means and measuring first angle data detected by said angle detecting means of said scanning means at a stop, a second angle measuring means for measuring second angle data detected by said angle detecting means of said scanning means when light rays deflected by said scanning means during rotation strike said light position measuring means, and a calculating means for comparing said first angle data and said second angle data and calculating an amount of delay of said phase.