Color image forming apparatus

An electrophotographic color image forming apparatus to develop an electrostatic latent image with a developer to form an image, the apparatus comprising:

• a photoconductor to bear the electrostatic latent image to be developed with the developer;
• and
• an optical writing device to expose the photoconductor,
• the optical writing device including:
• a light-emitting element to irradiate the photoconductor with light;
• a light emission control element to control light emission of the light-emitting element;
• a deflector element that is a multifaceted reflector disposed on an emission light path of the light from the light-emitting element, the reflector to he rotated by a signal inputted from an external device and deflect the light with which a surface of the reflector is irradiated to scan the photoconductor with the light in one direction;
• a synchronization detection element to detect a write start timing of the electrostatic latent image with the light with which the photoconductor is irradiated;
• a memory that stores an execution condition for correcting a color shift between a plurality of colors and a color shift correction value for correcting the color shift, the memory that stores a first light amount of the light-emitting element when the color shift is corrected;
• and
• processing circuitry configured to correct the color shift by adjusting the write start timing from when the synchronization detection element detects light to when light emission control by the light emission control element according to image data is started, and to correct a detection shift generated when a light amount of light incident on the synchronization detection element fluctuates,
• the processing circuitry configured to calculate a detection shift correction value of the detection shift of the synchronization detection element, using the first light amount and a second light amount determined as a lighting condition of the light-emitting element, and add the detection shift correction value to the color shift correction value.