Patent ID: 7499204

Claim:
An optical scanning apparatus that forms a latent image upon a photosensitive member, the apparatus comprising: a rotational polygonal mirror that is provided with a plurality of reflective surfaces that deflect a light beam in a main scanning direction; a resonant driving type mirror that deflects the light beam in a sub-scanning direction so as to reduce the influence of surface inclination in the reflective surfaces of said rotational polygonal mirror relative to the rotational axis of said rotational polygonal mirror; and a driving signal supply unit that supplies a driving signal of a frequency less than the resonance frequency of said resonant driving type mirror to said resonant driving type mirror in a first section, in order to bring the deflection angle of said resonant driving type mirror to a first target deflection angle, keeps the deflection angle of said resonant driving type mirror at the first target deflection angle in a second section, and supplies a driving signal of a frequency less than the resonance frequency of said resonant driving type mirror to said resonant driving type mirror in a third section, in order to bring the deflection angle of said resonant driving type mirror to a second target deflection angle, the first section being a section in which the latent image is not formed, the second section being a section that follows the first section and in which the latent image is formed, and the third section being a section that follows the second section and in which the latent image is not formed, and the sections being included in the light beam deflection cycle of said rotational polygonal mirror.