LIGHT SCANNING UNIT AND IMAGE FORMING APPARATUS USING THE SAME

摘要

A light scanning unit includes: a light source generating and irradiating at least one beam corresponding to an image signal; a beam deflector deflecting and scanning the beam irradiated by the light source; and an f-theta lens forming an image from the beam deflected by the beam deflector onto a surface to be scanned, the f-theta lens being provided as one lens and satisfies the following equation (2): $\begin{array}{cc}-0.2<\frac{\mathrm{SAG}1+\mathrm{SAG}2}{d_2}<0.2& \left(2\right)\end{array}$ where SAG 1 is Z value of an incident surface of the f-theta lens, which faces the beam deflector, SAG 2 is Z value of the exit surface of the f-theta lens, which faces the surface to be scanned, based on an XYZ coordinate system in which a main scanning plane is a Y-Z plane and a sub-scanning plane is an X-Z plane, and d₂ is a center thickness of the f-theta lens.