Image forming apparatus, optical scanning apparatus, and auto light power control method

An auto light power control method of an image forming apparatus including a light source having a plurality of light-emitting portions, a rotating polygonal mirror that deflects a beam that is emitted from the light source and has a plurality of mirror planes, and a photosensitive member which is exposed by the beam in an image period which is included in one scanning cycle of the beam the one scanning cycle comprising the image period during which exposure of the photosensitive member is performed based on an inputted image data and a non-image period during which the exposure of the photosensitive member is not performed, the method comprising:

• a step of selecting a light-emitting portion from among the plurality of light-emitting portions, the selected light-emitting portion being used to emit the beam during the image period;
• a step of detecting a light power of the beam emitted from any of the plurality of light-emitting portions;
• and
• a step of making the selected light-emitting portion emit the beam during the non-image period and executing auto light power control for the selected light-emitting portion in accordance with the detection result of the beam obtained by the detection step,
• wherein the step of making and executing does not execute the auto light power control for at least one of non-selected light-emitting portions from among the plurality of light-emitting portions.

An optical scanning apparatus, comprising:

• a light source having a plurality of light-emitting portions;
• a rotating polygonal mirror that deflects a beam that is emitted from the light source to expose a photosensitive member in an image period that is included in one scanning cycle of the beam, the one scanning cycle comprising the image period during which exposure of the photosensitive member is performed based on an inputted image data and a non-image period during which the exposure of the photosensitive member is not performed the rotating polygonal mirror having a plurality of mirror planes;
• a selection unit which selects a light-emitting portion from among the plurality of light-emitting portions, the selected light-emitting portion being used to emit the beam during the image period;
• a detection unit which detects a light power of the beam emitted from any of the plurality of light-emitting portions;
• and
• a control unit which makes the selected light-emitting portion emit the beam during the non-image period and executes the auto light power control for the selected light-emitting portion in accordance with the detection result of the beam obtained by the detection unit,
• wherein the control unit does not execute the auto light power control for at least one of non-selected light-emitting portions from among the plurality of light-emitting portions.