Patent ID: 8384752

Claim:
An optical scanning unit included in an image forming apparatus having at least one latent image carrier, the optical scanning apparatus comprising: at least one light emitter to emit a light beam; a rotary deflector to deflect and scan the light beam, said light beam emitted from the at least one light emitter, onto a surface of the at least one latent image carrier; and at least one inclination adjustment unit to adjust an inclination of a scan line corresponding to the light beam relative to a reference scan line on the at least one latent image carrier, wherein a controller is included in the image forming apparatus and is externally connected to the optical scanning unit, the controller being configured to change at least one of a linear velocity of the at least one latent image carrier and a rotation speed of the rotary deflector so as to change a ratio between the linear velocity of the at least one latent image carrier and a scan speed of the light beam for scanning the surface of the at least one latent image carrier, and the controller controlling the at least one inclination adjustment unit based on the ratio between the scan speed of the light beam and the linear velocity of the at least one latent image carrier to keep the scan line from inclining relative to the reference scan line, wherein the inclination of the scan line is adjusted by controlling a rotational angle of a stepping motor in the at least one inclination adjustment unit in accordance with the ratio of the linear velocity of the at least one latent image carrier and the scan speed of the light beam for scanning the surface of the at least one latent image carrier, and when the rotational angle of the stepping motor is controlled based on an obtained inclination adjustment amount, an up-and-down screw mounted on a rotation shaft of the stepping motor moves up and down, and one end portion of inclination adjustment unit on a side of the stepping motor is moved.