Image forming apparatus and optical scanning apparatus

An optical scanning apparatus provided in an image forming apparatus including a first photosensitive member and a second photosensitive member, the optical scanning apparatus comprising:

• a first light source configured to emit a first light beam to expose the first photosensitive member to the first light beam;
• a second light source configured to emit a second light beam to expose the second photosensitive member to the second light beam;
• a deflection unit including:
• a rotary polygon mirror configured to deflect the first light beam so that the first light beam scans the first photosensitive member, and to deflect the second light beam so that the second light beam scans the second photosensitive member;
• a motor configured to rotate the rotary polygon mirror;
• a drive unit configured to drive the motor;
• and a board on which the motor and the drive unit are mounted;
• first optical elements including a first lens and a mirror configured to guide the first light beam deflected by the rotary polygon mirror to the first photosensitive member, wherein the first light beam deflected by the rotary polygon mirror enters the first lens first in the first optical elements;
• second optical elements, including a second lens and a mirror, configured to guide the second light beam deflected by the rotary polygon mirror to the second photosensitive member, wherein the second light beam deflected by the rotary polygon mirror enters the second lens first in the second optical elements, the second lens being disposed opposite to the first lens with respect to the rotary polygon mirror;
• an optical box, to which the first light source and the second light source are attached, configured to contain the deflection unit, the first lens, and the second lens so that the deflection unit is located between the first lens and the second lens;
• and
• a temperature detecting element provided between the deflection unit and a side wall of the optical box on a side, on which the first light source and the second light source are not disposed, opposite to a side on which the first light source and the second light source are disposed with respect to the deflection unit in a direction perpendicular to a rotation axis of the rotary polygon mirror and an optical axis of the first lens, and between the first lens and the second lens in an optical axis direction of the first lens, the temperature detecting element being configured to detect an internal temperature of the optical box.

An image forming apparatus, comprising:

• four photosensitive members including a first photosensitive member, a second photosensitive member, a third photosensitive member, and a fourth photosensitive member, each of the four photosensitive members bearing a toner image, and each of the four photosensitive members corresponding to a different one of four toners including yellow toner, cyan toner, magenta toner, and black toner;
• a light scanning apparatus comprising:
• a first light source configured to emit a first light beam;
• a second light source configured to emit a second light beam;
• a third light source configured to emit a third light beam;
• a fourth light source configured to emit a fourth light beam;
• a deflection unit including:
• a rotary polygon mirror configured to deflect the first light beam, the second light beam, the third light beam, and the fourth light beam so that the first light beam scans the first photosensitive member, the second light beam scans the second photosensitive member, the third light beam scans the third photosensitive member, and the fourth light beam scans the fourth photosensitive member;
• a motor configured to rotate the rotary polygon mirror;
• a drive unit configured to drive the motor;
• and a board on which the motor and the drive unit are mounted;
• a first lens which the first light beam and the third light beam deflected by the rotary polygon mirror enter first, the first lens being included in a plurality of optical elements configured to guide the first light beam, the second light beam, the third light beam, and the fourth light beam to the first photosensitive member, the second photosensitive member, the third photosensitive member, and the fourth photosensitive member, respectively;
• a second lens which the second light beam and the fourth light beam deflected by the rotary polygon mirror enter first, the second lens being included in the plurality of optical elements and being disposed opposite to the first lens with respect to the rotary polygon mirror;
• an optical box, to which the first light source, the second light source, the third light source, and the fourth light source are attached, configured to contain the deflection unit, the first lens, and the second lens so that the deflection unit is located between the first lens and the second lens;
• and
• a temperature detecting element provided between the deflection unit and a side wall of the optical box on a side opposite to a side on which the first light source, the second light source, the third light source, and the fourth light source are disposed with respect to the deflection unit in a direction perpendicular to a rotation axis of the rotary polygon mirror and an optical axis of the first lens, and between the first lens and the second lens in an optical axis direction of the first lens, the temperature detecting element being configured to detect an internal temperature of the optical box;
• wherein the image forming apparatus further comprises:
• a transfer unit configured to transfer toner images on the four photosensitive members onto a sheet;
• and
• a control unit configured to correct a misregistration among the toner images to be transferred onto the sheet based on a detection result of the temperature detecting element.

A light scanning apparatus attached to an image forming apparatus comprising four photosensitive members including a first photosensitive member, a second photosensitive member, a third photosensitive member, and a fourth photosensitive member, each of the four photosensitive members bearing a toner image, and each of the four photosensitive members corresponding to a different one of four toners including yellow toner, cyan toner, magenta toner, and black toner, the light scanning apparatus comprising:

• a first light source configured to emit a first light beam;
• a second light source configured to emit a second light beam;
• a third light source configured to emit a third light beam;
• a fourth light source configured to emit a fourth light beam;
• a deflection unit including:
• a rotary polygon mirror configured to deflect the first light beam, the second light beam, the third light beam, and the fourth light beam so that the first light beam scans the first photosensitive member, the second light beam scans the second photosensitive member, the third light beam scans the third photosensitive member, and the fourth light beam scans the fourth photosensitive member;
• a motor configured to rotate the rotary polygon mirror;
• a drive unit configured to drive the motor;
• and a board on which the motor and the drive unit are mounted;
• a first lens which the first light beam and the third light beam deflected by the rotary polygon mirror enter first, the first lens being included in a plurality of optical elements configured to guide the first light beam, the second light beam, the third light beam, and the fourth light beam to the first photosensitive member, the second photosensitive member, the third photosensitive member, and the fourth photosensitive member, respectively;
• a second lens which the second light beam and the fourth light beam deflected by the rotary polygon mirror enter first, the second lens being included in the plurality of optical elements and being disposed opposite to the first lens with respect to the rotary polygon mirror;
• an optical box, to which the first light source, the second light source, the third light source, and the fourth light source are attached, configured to contain the deflection unit, the first lens, and the second lens so that the deflection unit is located between the first lens and the second lens;
• and
• a temperature detecting element provided between the deflection unit and a side wall of the optical box on a side opposite to a side on which the first light source, the second light source, the third light source, and the fourth light source are disposed with respect to the deflection unit in a direction perpendicular to a rotation axis of the rotary polygon mirror and an optical axis of the first lens, and between the first lens and the second lens in an optical axis direction of the first lens, the temperature detecting element being configured to detect an internal temperature of the optical box.