Control circuit, image forming apparatus, and control method

A control circuit for an image forming apparatus includes a plurality of beam sources each configured to emit a beam, a photodetector configured to detect an intensity of the beam emitted from the plurality of beam sources, a processor configured to measure a slope efficiency of each beam source by controlling each beam source to emit the beam with different drive currents, and acquiring the intensity of each beam detected by the photodetector, and while a job is performed by the image forming apparatus, detect a current flowing in each beam source, determine an adjustment amount of a drive current for each beam source so that the beam source emits the beam at a predetermined output, based on the detected current and the measured slope efficiency, and adjust the drive current with the determined adjustment amount.