Patent ID: 8004735

Claim:
An optical scanning device, comprising: a polygon scanner that includes: a polygon mirror that reflects a light beam emitted from a light source, a bearing that rotatably supports the polygon mirror, a polygon motor that rotates the polygon mirror, and a scanner board on which a component of the polygon motor is mounted; an optical housing in which the polygon scanner is mounted; and a scanner-unit attachment portion to which the polygon scanner is attached, the scanner-unit attachment portion including a convex portion protruded from a bottom plate of the optical housing, the convex portion being formed in a shape of a wall which is continuous without forming any chasm along a circumferential portion of the scanner board, and the convex portion surrounding the polygon mirror from a planar direction of the scanner board, wherein the scanner board makes a tight contact with an upper surface of the convex portion in direct contact with each other, and a bottom portion of the polygon scanner is covered and sealed by the convex portion and the bottom plate of the optical housing in a closed space formed by the scanner-unit attachment portion.