Patent ID: 9335652
Filing Date: 2016-05-10
CPC Classification: G03G

Claim Text:
1. An optical writing device comprising: a plurality of light-emitting points; a plurality of drive units for supplying drive currents to the plurality of light-emitting points respectively; a photodetector for outputting signals indicating quantities of light entering thereto from the respective light-emitting points; a gain switch unit for outputting photodetection signals obtained by amplifying the signals output from the photodetector in regard to the respective light-emitting points with gains preset for the respective light-emitting points; and a control unit for controlling the drive units such that the photodetection signals output from the gain switch unit in regard to the respective light-emitting points coincide with a value substantially equal to a predetermined reference value, wherein the gains for the respective light-emitting points are preset based on the distances between the photodetector and the respective light-emitting points; wherein the gain switch unit comprises at least one capacitor; and wherein the control unit is configured to set the gains for the respective light-emitting points preliminarily in the gain switch unit by determining a charge time on the capacitor for each of the light-emitting points based on the photodetection signal in regard to each of the light-emitting points.