Optical scanning apparatus

An optical scanning apparatus comprising:

• a light deflector that includes a rotary polygon mirror and is configured to deflect a light beam emitted from a light source;
• and
• an optical box that includes a bottom surface that supports the light deflector and a top surface that faces the bottom surface, wherein the optical box includes an aperture through which the light beam reflected by the light deflector can be emitted;
• wherein the top surface of the optical box is constituted by a single lid, and the top surface includes a first surface and a second surface provided at different positions in a direction from the aperture to the rotary polygon mirror,
• wherein the first surface is disposed closer to the rotary polygon mirror than the second surface in the direction directed from the aperture to the rotary polygon mirror,
• wherein the first surface is disposed closer to the rotary polygon mirror than the second surface in a rotation axis direction of the rotary polygon mirror and is disposed closer to the bottom surface than an edge portion of the light deflector positioned farthest from the bottom surface,
• wherein the top surface of the optical box includes a convex portion that is provided at the same position as the rotary polygon mirror in the direction from the aperture to the rotary polygon mirror in such a way as to protrude in a direction away from the bottom surface in the rotation axis direction of the rotary polygon mirror,
• wherein a third surface of the convex portion located at a remotest position from the bottom surface is positioned farther from the bottom surface than the first surface in the rotation axis direction of the rotary polygon mirror, and
• wherein a lower edge portion of the convex portion that is adjacent to the rotary polygon mirror is disposed outside a circumscribed circle of the rotary polygon mirror.