Optical scanning device and image forming apparatus

An optical scanning apparatus comprising:

• a light source;
• a deflector configured to scanningly deflect a beam emitted from said light source;
• a scanning lens configured to image the beam deflected by said deflector on a surface to be scanned;
• a casing accommodating said light source, said deflector and said scanning lens;
• and
• an elastic member urging said scanning lens toward said casing in a direction of an optical axis,
• wherein said scanning lens is provided with an abutment surface at a beam emergent side of said scanning lens, said abutment surface abutting to said casing, and
• wherein a free end portion of said elastic member and a top surface of said scanning lens limit movement of said scanning lens in a direction opposite a assembling direction of said scanning lens, and
• wherein in a state that said scanning lens contacts a positioning portion of said casing with respect to the assembling direction, a gap is provided between the free end portion of said elastic member and the top surface of said scanning lens with respect to the assembling direction.

An optical scanning apparatus comprising:

• a light source;
• a deflector configured to scanningly deflect a beam emitted from said light source, said deflector including a rotatable polygonal mirror;
• a first optical system including at least one lens and configured to direct the beam to a reflecting surface of said rotatable polygonal mirror;
• a second optical system including at least one lens, said second optical system being configured to image the beam deflected by said deflector on a surface to be scanned;
• and
• a casing holding at least said first optical system and said second optical system;
• wherein said casing is provided with positioning portions provided at positions opposing said first optical system and said second optical system with respect to assembling directions of said lenses, respectively, and configured to position said lenses, said casing is provided with limiting portions at positions opposing said first and second optical systems with respect to the directions opposite the assembling directions, respectively, and configured to limit movement of the lenses of said first and optical systems;
• wherein the lenses of said first and second optical systems are provided with engaging portions engaged with limiting portions, respectively, and
• wherein a moving direction of the beam on the surface to be scanned by movement of said lens of said first optical system away from said positioning portion is opposite a moving direction of the beam on the surface to be scanned by a movement of said lens of said second optical system away from said positioning portion.