| 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-&thetas; lens forming an image from the beam deflected by the beam deflector onto a surface to be scanned, the f-&thetas; lens being provided as one lens and satisfies the following equation (2): - 0.2 < SAG 1 + SAG 2 d 2 < 0.2 ( 2 ) where SAG 1 is Z value of an incident surface of the f-&thetas; lens, which faces the beam deflector, SAG 2 is Z value of the exit surface of the f-&thetas; 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-&thetas; lens.
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