Oscillating device, optical scanning device using the same, image display apparatus, and control method of the oscillating device

Provided is an oscillating device, which can adjust the oscillation angle and the phase of a movable plate easily with a simple constitution. A light scanning device acting as the oscillating device comprises a mirror element for oscillating the movable plate having a mirror film, a control circuit having a duty ratio adjusting unit and a function to change the duty ratio of the pulse voltage, so that it applies the pulse voltage thereby to drive a vertical comb of the mirror element, and an oscillation detecting unit for detecting the oscillations of the movable plate. On the bases of the movable plate oscillations detected by the oscillation detecting unit, the control circuit controls the duty ratio adjusting unit thereby to change the duty ratio of the pulse voltage. When the pulse voltage having the changed duty ratio is applied to the mirror element, the period of applying the voltage to the vertical comb at the oscillating time of the movable plate changes so that the phase and the oscillation angle of the oscillations of the movable plate change. By the feed-back control of the duty ratio according to the oscillations of the movable plate, the movable plate can be controlled to oscillate in the proper phase and at the proper oscillation angle.