Patent ID: 8059146

Claim:
An exposure device comprising: a plurality of light emitting elements; a load; a first supplying unit that supplies a driving current to one of (i) light emitting elements which are used to form an image among the plurality of light emitting elements and (ii) the load, in accordance with a modulation signal, wherein the first supplying unit supplies a bias current to another one of (i) the light emitting elements which are used to form the image and (ii) the load; a second supplying unit that supplies the bias current to light emitting elements which are not used to form the image among the plurality of light emitting elements, regardless of the modulation signal; and a third supplying unit that supplies to the respective light emitting elements a bias voltage which is common to the plurality of light emitting elements and which is obtained by averaging voltages between terminals of the plurality of light emitting elements when the plurality of light emitting elements are turned off, wherein after the bias voltage is supplied, the first supplying unit supplies the bias current, which is set based on the bias voltage, to the another one of (i) the light emitting elements which are used to form the image and (ii) the load, and after the bias voltage is supplied, the second supplying unit supplies the bias current, which is set based on the bias voltage, to the light emitting elements which are not used to form the image among the plurality of light emitting elements, regardless of the modulation signal.