Patent ID: 7652786

Claim:
An image forming apparatus comprising: a latent image carrier rotated in a subscan direction; a light source for emitting a light beam; an optical scanner operative to deflectively scan the light beam from the light source along a main scan direction substantially perpendicular to the subscan direction and to irradiate the scanned beam on said latent image carrier; and a controller which controls the light source and the optical scanner thereby forming a latent image on the latent image carrier, wherein the optical scanner includes a fine adjustment mechanism which has a mirror plane which is pivotally movable along the subscan direction with an axis in the main scan direction and deflects the light beam from the light source or the scanned beam along the subscan direction, wherein the controller controls a position of the mirror plane along the subscan direction and stops the mirror plane along the subscan direction while scanning the light beam along the main scanning direction thereby adjusting the scanned beam for its position on the latent image carrier with respect to the subscan direction, wherein the optical scanner comprises: an inner movable member having a deflector mirror plane as the mirror plane for reflecting the light beam from the light source; an outer movable member for pivotally supporting the inner movable member about a first axis; a support member for pivotally supporting the outer movable member about a second axis different from the first axis; and a mirror driver section for driving the inner movable member into pivotal motion about the first axis and the outer movable member into pivotal motion about the second axis, wherein the controller controls the mirror driver section to drive the deflector mirror plane into reciprocal oscillation about a main-scan deflection axis defined by either one of the first axis and the second axis thereby scanning the light beam from the light source along the main scan direction, wherein the controller controls the mirror driver section to drive the deflector mirror plane into pivotal motion about a fine adjustment axis defined by the other axis before starting the reciprocal oscillation and to stop the pivotal motion of the deflector mirror plane about the fine adjustment axis during the reciprocal oscillation, thereby adjusting the scanned beam for its position on the latent image carrier with respect to the subscan direction, wherein the mirror driver section drives the deflector mirror plane into pivotal motion about the main-scan deflection axis in a resonant mode, and wherein the mirror driver section positions the deflector mirror plane by pivotally moving the same about the fine adjustment axis in a non-resonant mode.