Patent ID: 6504558
Filing Date: 2003-01-07
Classification: G06K,H04N

Abstract:
An image forming apparatus comprising:a light source for emitting a light beam modulated according to an image signal applied thereto; an optical deflector for repeatedly deflecting the light beam emitted from said light source; a focusing optical system for focusing the light beam deflected by said optical deflector on a surface to be scanned to form a light spot there, the surface to be scanned being scanned repeatedly in a main-scanning direction; a photosensitive member arranged at the surface to be scanned and exposed selectively to the light spot, said photosensitive member having an image forming region and blank regions arranged at opposite ends of the image forming region in the main-scanning direction; a developing unit for causing toner to adhere to unexposed areas of said photosensitive member and developing an image; a photodetector for receiving part of the light beam emitted from said light source; an automatic power control circuit for controlling an output power of said light source on the basis of an output of said photodetector; a synchronizing signal sensor for receiving part of the light beam deflected by said optical deflector and outputting a synchronizing signal; and a drive circuit for driving said light source according to the image signal applied thereto during a period of scanning the image forming region of said photosensitive member by the light spot and for energizing said light source during periods of scanning the blank regions of said photosensitive member by the light spot thereby exposing the blank regions to prevent toner from adhering thereto, wherein said automatic power control circuit controls the output power of said light source based on a detection by said photodetector during at least one of the periods of scanning the blank regions of said photosensitive member by the light spot, and wherein said drive circuit regulates the timing of starting an operation of forming an image on said photosensitive member on the basis of the synchronizing signal.