Patent ID: 8810622

Claim:
A light scanning apparatus, comprising: a light source configured to emit a light beam; a beam splitter configured to split the light beam emitted from the light source into a first light beam and a second light beam; a rotary polygon mirror configured to deflect the first light beam split by the beam splitter to scan a photosensitive member with the first light beam; a motor configured to rotate the rotary polygon mirror; a first lens configured to guide the first light beam deflected by the rotary polygon mirror to the photosensitive member; an optical sensor configured to receive the second light beam reflected by the beam splitter; a second lens disposed on a line segment which connects the beam splitter and the optical sensor on an opposite side of the first lens with respect to the light beam which enters the beam splitter so that the second light beam split by the beam splitter enters the second lens, the second lens being configured to guide the entered second light beam to the optical sensor; and an optical box on which the beam splitter, the first lens, the rotary polygon mirror, the motor, the optical sensor, and the second lens are disposed, wherein the optical box comprises a wall standing from a bottom surface of the optical box between a region in which the rotary polygon mirror and the motor are disposed and a region in which the second lens is disposed, wherein a height of the wall from the bottom surface of the optical box is higher than a height from the bottom surface of the optical box to the rotary polygon mirror, wherein the beam splitter is mounted on the bottom surface of the optical box, wherein one end of the beam splitter in a direction parallel to the bottom surface is disposed in a position adjacent to the wall and in contact with the wall, and wherein the wall and the beam splitter separate the region in which the second lens is disposed from the region in which the rotary polygon mirror and the motor are disposed.