Patent ID: 8107148

Claim:
A curvature correction device used in an optical scanning unit that optically scans a scan target with a light beam, the optical scanning unit including a light beam emitter configured to emit the light beam, a deflection unit configured to deflect the light beam in a main scanning direction of the optical scanning unit, and a reflection mirror configured to reflect the light beam, the curvature correction device comprising: a holder configured to hold the reflection mirror in a state in which the reflection mirror is forcibly bent in a first direction; and a first pushing unit configured to push the reflection mirror held by the holder to bend the reflection mirror in a second direction opposite the first direction in which the reflection mirror is forcibly bent by the holder; a second pushing unit configured to directly push an end portion of the reflection mirror to adjust an inclination of the reflection mirror, the curvature correction device being configured to correct the curvature of the main scanning line on the surface of the scan target by adjusting an amount at which the first pushing unit pushes the reflection mirror, and the holder including a stiffness relatively larger than a stiffness of the reflection mirror, wherein the holder includes a support member extending from the holder and configured to directly support the reflection mirror and a pressing member configured to press the reflection mirror, the holder being configured to hold the reflection mirror in the forcibly bent state by pressing the reflection mirror with the pressing member at a position relatively closer to each end in a longitudinal direction of the reflection mirror than the support member, while supporting the reflection mirror with the support member at each end portion in the longitudinal direction of the reflection mirror, the reflection mirror includes a mirror face and a back face, and wherein the holder is configured so that the support member supports and is in surface contact with the mirror face of the reflection mirror while the pressing member presses the reflection mirror from a side of the back face of the reflection mirror, the first pushing unit is configured to push the reflection mirror at a position relatively closer to a middle portion in the longitudinal direction of the reflection mirror than the support member supporting the reflection mirror at the each end portion of the longitudinal direction of the reflection mirror, the first pushing unit is configured to push the reflection mirror from a side of a back face of the reflection mirror, and the second pushing unit pushes in a direction parallel to a pushing direction of the first pushing unit.