Patent attributes
Disclosed is an image forming apparatus capable of keeping an oscillation angle of an oscillating mirror at a constant value based on control of a drive frequency. In this image forming apparatus, a semiconductor laser emits a light beam, and an oscillating mirror reflects the light beam emitted from the semiconductor laser, onto a target surface in a scanning manner. An oscillating-mirror drive circuit unit supplies a drive signal having a feature that a drive voltage varies based on a drive frequency, to the oscillating mirror, to reciprocatingly oscillate the oscillating mirror within a given angular range. A voltage-variation detection circuit detects a variation amount of the drive voltage, and a drive-frequency generation circuit alters the drive frequency depending on the variation amount of the drive voltage detected by the voltage-variation detection circuit.
