Patent ID: 7595812

Claim:
An image forming apparatus, comprising: a light source configured to emit a light beam in a main scanning direction according to image data for forming an image; a control unit configured to control the light source by variably controlling a cycle of a pixel clock for each pixel in the main scanning direction; a plurality of detectors configured to detect the light beam emitted from the light source in the main scanning direction; a correcting unit configured to correct an image position and image magnification in the main scanning direction by changing the cycle of the pixel clock for each pixel based on detection results of each of the detectors, wherein the correcting unit is configured to correct the image position and the image magnification in the main scanning direction by dividing the main scanning direction into a plurality of areas based on a position of each of the detectors, and changing the cycle of the pixel clock for each pixel in each of the areas independently, and the detectors are arranged at positions corresponding to boundaries between the areas in the main scanning direction; a unit configured to change a number of the areas; an area setting changing unit configured to change positions of the boundaries based on the detection results of the detectors; and a light beam scanning device, wherein the area setting changing unit is configured to change a setting of the areas when the light beam scanning device is replaced.