Patent ID: 7777774

Claim:
An optical scanning device configured to deflect a beam, to converge the deflected beam, and to direct the deflected beam toward a scanning surface, so that an optical scanning of the scanning surface is performed by an optical spot formed on the scanning surface by the deflected beam, said optical scanning device comprising: a beam separating device configured to separate a part of the beam before the beam is incident on the scanning surface and to direct the part of the beam toward a detection surface that is optically equivalent to the scanning surface, wherein a scan line bending state on said detection surface, which is equivalent to a scan line bending occurring on the scanning surface, is detected; a scanning position detection device configured to detect a position of a scanning line on said detection surface; and a beam deflection control device disposed on a light path of the beam before the beam is incident on the scanning surface and including a plurality of beam deflection control units continuously arranged in a main scanning direction, the beam deflection control device including a plurality of electrodes, each of the plurality of beam deflection control units including a liquid crystal film, at least two of the plurality of electrodes, the at least two of the plurality of electrodes corresponding to the liquid crystal film, and a driver unit configured to control the liquid crystal film independent of a remainder of the plurality of electrodes, wherein said beam separating device comprises said beam deflection control device, a beam deflection amount provided to the beam by the beam deflection control device is controlled to control a scanning characteristic of the optical scanning, and said scanning position detection device includes a number of optical sensors, which number equals a number of the plurality of beam deflection control units, said optical sensors being disposed at positions corresponding to positions of respective beam deflection control units and detecting subscanning-directional positions of optical spots.