| 摘要 |
PURPOSE:To satisfactorily correct a curve of a scanning line, and to contrive to obtain an inclination correcting function which follows up a scan, by allowing plural luminous fluxes to be made incident on an optical deflector in a state that they are not parallel to each other, and also, reflecting them even times in the optical deflector, and emitting them. CONSTITUTION:At the time of scanning simultaneously on a medium to be scanned, by two luminous fluxes, they are allowed to be made incident so as to become off-axis luminous fluxes against an image forming lens 5, and by constituting the image forming lens 5 of an (f)-theta lens system consisting of a concave lens 51 and a convex lens 52, the image forming performance on the medium to be scanned is maintained satisfactorily. Also, by using a roof polygon mirror provided with plural pieces of pair of reflecting surfaces for crossing each other at 90 deg., the inclination of an optical deflector which follows up a scan is corrected satisfactorily. Also, a scanning line curve on the medium to be scanned, which is generated at the time when the luminous flux is made incident diagonally on the optical deflector which is reflected it even times appears in the direction reverse to a curve generated at the time when the image forming lens has been used outside of the axis, therefore, the scanning line curve on the medium to be scanned is offset and corrected. In such a way, the inclination which follows up a scan and the scanning line curve on the medium to be scanned can be corrected satisfactorily. |
