Image forming apparatus and laser drive control method therein

Abstract

An image forming apparatus for forming an image by modulating laser light in correspondence with an image signal. A pulsewidth modulation signal is generated in correspondence with input image data. A laser drive control circuit has a photosensor PD which detects laser light emitted from a laser diode LD and generates a detection current, a resistor which generates a detection voltage corresponding to the detection current outputted from the photosensor PD, a buffer in which the generated detection voltage is inputted, an amplifier which amplifies an output from the buffer, and a constant current source and a switch to add a predetermined current to the detection current for compensation for reduction of output voltage due to offset voltages of the buffer and the amplifier. Control data for controlling maximum and minimum pulsewidths in the pulsewidth modulation signal are obtained based on the detection voltage, and generation of the pulsewidth modulation signal is controlled.

Dependencies are inferred from the claim text.