Patent ID: 7710625

Claim:
A light scanning apparatus which makes a light beam scan along a main scanning direction on an effective scanning region which has a predetermined width, comprising: a light source which emits the light beam; a deflector which includes an oscillation mirror which oscillates about an oscillatory axis which is orthogonal or approximately orthogonal to the main scanning direction, deflects the light beam emitted from the light source using the oscillation mirror, and makes the light beam scan a second scanning range which contains but extends beyond a first scanning range which corresponds to the effective scanning region; a detector which detects the scanning light beam which moves through a position which is outside the first scanning range but is within the second scanning range, and outputs a signal; and a controller which controls a mirror drive signal fed to the oscillation mirror based on the output signal from the detector and accordingly adjusts an amplitude of the oscillation mirror, wherein the controller detects a change of the amplitude of the oscillation mirror in accordance with the output signal and stops driving the oscillation mirror when the change of the amplitude of the oscillation mirror exceeds a value determined in advance.