Patent ID: 8593495

Claim:
An image forming apparatus comprising: a photosensitive member; a plurality of light-emitting portions configured to output beams; a scanning unit configured to deflect the beams so that the beams scan the photosensitive member; a detecting unit configured to receive the beam or beams deflected by the scanning unit and generate a detection signal; and a control unit configured to cause the plurality of light-emitting portions to output the beams to generate the detection signal, and based on the detection signal generated by the detecting unit, control output timing of the beams from the plurality of light-emitting portions, the control unit performing a light quantity control in which a quantity of the beam emitted from each of the plurality of light-emitting portions is controlled based on the generated detection signal, wherein the control unit is further configured to: select a first mode in which at least two light-emitting portions among the plurality of light-emitting portions output the beams for detection by the detection unit, and a second mode in which one light-emitting portion among the plurality of light-emitting portions outputs the beam for detection by the detection unit; and select the first mode prior to performing the light quantity control and control a value of drive current so that the value of drive current supplied to at least two light-emitting portions in a case where the first mode is selected is smaller than the value of drive current supplied to one light-emitting portion in a case where the second mode is selected.