Provided is a light scanning apparatus including a deflecting unit, and a first optical system for guiding a light flux deflected by the deflecting unit to a surface to be scanned. A width of the light flux immediately before entering the deflecting unit is smaller than that of a deflecting surface of the deflecting unit in a main scanning cross section. Only a part of the light flux incident on the deflecting unit reaches a plurality of image heights on the surface via the deflecting surface in the main scanning cross section. A distance between an on-axis image height and an image height closest to the on-axis image height on one side and that between the on-axis image height and an image height closest to the on-axis image height on the other side, with respect to the on-axis image height among the plurality of image heights are appropriately set.

A mirror fastener fastens a first end portion of a mirror to a first mirror support portion of a housing. A second mirror support portion includes a pair of partitioning surfaces and a concave surface. The pair of partitioning surfaces oppose an end surface of a second end portion of the mirror while an interval is provided between the pair of partitioning surfaces and the end surface. The concave surface is formed between the pair of partitioning surfaces and opposes the end surface of the second end portion while an interval larger than the interval between the pair of partitioning surfaces and the end surface is provided between the concave surface and the end surface. An adhesive bonds the end surface of the second end portion and the pair of partitioning surfaces.

The optical scanning device comprises a semiconductor laser, which serves as a light source for exposing the surface of the photosensitive body; a polygon mirror, which deflects the light from the semiconductor laser in the main scanning direction; and a cylindrical lens, which is positioned between the semiconductor laser and the polygon mirror and deflects the light from the semiconductor laser in the sub-scanning direction to irradiate the polygon mirror.

The cylindrical lens includes an incident surface, through which light from the semiconductor laser enters, and an exit surface, through which the incident light exits. The curvature direction of the incident surface in the main scanning direction and the curvature direction of the exit surface in the main scanning direction are formed to be different from each other.

A scanning optical device includes a light source, an optical deflector, a scanning optical system, a frame, and a leaf spring. The optical deflector includes a polygon mirror rotatable about a rotation axis extending in a first direction perpendicular to a main scanning direction. The scanning optical system includes a scan lens. The scan lens includes a lens portion and a flange extending in the main scanning direction from an end of the lens portion in the main scanning direction. The frame includes a contact wall positioned further away, than the flange, from the rotation axis in a second direction perpendicular to the main scanning direction and the first direction. The leaf spring includes a base and a first arm configured to hold the contact wall and the flange in combination with the base and bias the flange toward the contact wall.

The optical scanning device comprises a light source, a polygon mirror 15, an f lens 19, and a BD sensor. The f lens is configured such that the region emitting light from the light source to expose the surface of the photosensitive body and the region emitting light from the light source to reach the BD sensor are continuous.

The light emitted from the light source discharges static electricity from areas outside both ends of the actual printing region in the main scanning direction on the photosensitive surface.

The f lens includes: a first region that transmits light reaching the actual printing region; a second region provided at both longitudinal ends of the first region; and a third region provided at both longitudinal ends of the second region. The light reaching the BD sensor from the polygon mirror is configured to pass through the third region.

An optical scanning apparatus includes a semiconductor laser, a coupling lens, a polygon mirror, a motor, an optical scanning system including a first scanning lens with an optical surface, a housing, a cover, and a partition with an opening closed with the first scanning lens. Shifting amounts of a focus position of a beam with respect to a reference imaging plane in a main scanning direction are in relations A<0 and A<B<C, where A mm and B mm are shifting amounts when the semiconductor laser, the coupling lens, and the optical scanning system are at a normal ambient temperature and at an upper-limit ambient temperature, respectively, and C mm is a shifting amount when the semiconductor laser and the coupling lens are at the normal ambient temperature and the first scanning lens is at a first temperature.

An optical scanning device comprises a component fixer including a one-end fixer that fixes one end of an optical component and an other-end fixer that fixes an other end of the optical component, wherein the one-end fixer includes a one-end positioner that positions an other surface of the one end and at least one one-end side protruding portion that supports the other surface in an inclined state with respect to a horizontal plane, the other-end fixer includes an other-end positioner that positions the other surface of the other end and at least two other-end side protruding portions that support the other surface in an inclined state with respect to the horizontal plane, and an other-end adhesive fixer fixes the other end to the other-end positioner and includes portions at which the other surface is fixed to the at least two other-end side protruding portions.