Patent ID: 9658559
Date: 2017-05-23
CPC Classifications: B41J,G02B,G03G,H04N

Claim:
1. An image forming apparatus comprising: a light source including a plurality of light-emitting portions each of which outputs a light beam for exposing a photosensitive member; a light reception unit configured to receive a light beam individually output by the plurality of light-emitting portions, and output a detection signal corresponding to a light quantity of the received light beam; a deflection unit configured to deflect the light beam so as to scan on the photosensitive member; a drive unit configured to perform switch-driving of the plurality of light-emitting portions by supplying a drive current to each of the plurality of light-emitting portions in accordance with image data in an image period in which the light beam deflected by the deflection unit scans on the photosensitive member in order to form an image on the photosensitive member, and supply a drive current for controlling a light quantity of the plurality of light-emitting portions in a first section of a non-image period in which the light beam deflected by the deflection unit does not scan on the photosensitive member, the image period and the non-image period constituting a scan cycle; a determination unit configured to determine a value of the drive current for performing switch-driving of the plurality of light-emitting portions, based on the detection signal output by the light reception unit with respect to the light beam that is individually output by the plurality of light-emitting portions during the non-image period; and a generation unit configured to generate image data in a second section of the non-image period, wherein the determination unit is further configured to determine a value of a bias current caused to flow through at least the plurality of light-emitting portions regardless of image data during the image period by determining a value of a first drive current for setting a light quantity of a light beam incident on the light reception unit during the non-image period to a first target light quantity, and determining a value of a second drive current for setting a light quantity of the light beam incident on the light receiving unit to a second target light quantity that is different from the first target light quantity, and the determination unit further determines the value of the drive current for performing switch-driving of the plurality of light-emitting portions, based on the image data, the drive current corresponding to the first drive current and the bias current, upon the image data being generated by the generation unit in the second section of the non-image period, wherein the determination unit further includes a subtraction unit configured to subtract the value of the bias current from the value of the first drive current, and a correction unit configured to determine the value of the drive current by correcting a subtraction result of the subtraction unit, using a correction coefficient corresponding to a sensitivity of the photosensitive member, upon the value of the bias current being determined in the first section of the non-image period, the subtraction unit determines the value of the drive current for performing switch-driving of the plurality of light-emitting portions, by subtracting the value of the bias current from the value of the first drive current, and the correction unit determines the value of the drive current corrected using the correction coefficient in the second section of the non-image period.