Patent ID: 6046835
Filing Date: 2000-04-04
Classification: B41J,G02B,H04N

Abstract:
A scanning optical apparatus comprising:light source means;an optical deflector for deflecting a light beam emitted by said light source means;optical means for causing the light beam emitted by said light source means to be obliquely incident on a deflection surface of said optical deflector within a sub scanning section; andan imaging optical system for forming an image of the light beam deflectively reflected by said optical deflector on a surface to be scanned, said imaging optical system having a sub-scanning-direction lateral magnification which changes in accordance with a distance away from an on-axis position to an off-axis position along a main scanning direction,wherein letting .beta. be the sub-scanning-direction lateral magnification of said imaging optical system at the on-axis position, .beta.' the sub-scanning-direction lateral magnification at the off-axis position, dZ an image height displacement of an on-axis light beam upon elevation of an atmospheric temperature, dZ' an image height displacement difference between the on-axis light beam and an off-axis light beam upon elevation of the atmospheric temperature, and .DELTA.dZ' a correction residual of the difference dZ', when the correction residual .DELTA.dZ' is given by:.DELTA.dZ'=.vertline.dZ'-(.beta.'/.beta.-1).multidot.dZ.vertline.the following condition is satisfied:.DELTA.dZ'.ltoreq.20 (.mu.m).