Image forming apparatus

摘要

An image forming apparatus controls a semiconductor laser such that first and second light beams among multiple light beams are successively incident on a BD sensor and measures the time interval between BD signals that correspond to the first and second light beams and are output from the BD sensor. Two light emitting elements that output two light beams for which the ratio between the light powers of two light beams detected by the detection unit falls within a predetermined range are set as light emitting elements that are to emit the first and second light beams when the time interval is to be measured. This suppresses measurement errors when measuring the interval between light beams emitted from two light emitting elements and improves correction accuracy for the image writing start positions of the light emitting elements.

主权项

1. An image forming apparatus that exposes a photosensitive member using a plurality of light beams, the image forming apparatus comprising:
a light source that includes a plurality of light emitting elements that each emit a light beam, the light source including at least three light emitting elements; a deflection unit configured to deflect the plurality of light beams emitted from the plurality of light emitting elements, such that the plurality of light beams scan the photosensitive member; a detection unit that is provided on a scanning path of the plurality of light beams deflected by the deflection unit, and is configured to output a detection signal indicating that a light beam deflected by the deflection unit has been detected due to the light beam being incident on the detection unit; a measurement unit configured to control the light source such that a first and second light beam are successively incident on the detection unit, and to measure a time interval between detection signals that are output from the detection unit and corresponds to the first and second light beams; and a control unit configured to, according to the time interval measured by the measurement unit, control relative emission timings for light beams from the plurality of light emitting elements that are based on image data, wherein among the plurality of light emitting elements, two light emitting elements are set as light emitting elements that are to emit the first and second light beams, the two light emitting elements outputting two light beams for which a ratio between light powers of the two light beams detected by the detection unit falls within a predetermined range, and wherein the image forming apparatus further comprises: a storage unit configured to store information indicating the first and second light beams that are to be used at a time of the measurement performed by the measurement unit and that are selected in advance based on light power measurement results when the light beams emitted from the plurality of light emitting elements are incident on the detection unit; and a setting unit configured to, in accordance with the information stored in the storage unit, set the two light emitting elements that are to emit the first and second light beams.