Patent ID: 7466472

Claim:
An image forming apparatus for obtaining an image by scanning with modulated light modulated in timing of a predetermined timing signal base on input image information, comprising: a part of adjusting, upon predetermined mark image measurement, the timing signal, for obtaining a required correction amount for a scan magnification of the modulated light, in particular in a measurement range of the predetermined mark image measurement; a part of adjusting, upon regular image forming operation, the timing signal, for obtaining the required correction amount for the scan magnification of the modulated light, in particular in the entire scanning range of the modulated light for regular image forming operation; a first adjusting part measuring the scan magnification of the modulated light, obtaining the required correction amount of the scan magnification of the modulated light by comparing the measured value with a reference value, and adjusting the timing signal with the required correction amount of the scan magnification of the modulated light, in prior to actual image forming operation; and a second adjusting part forming a predetermined mark image with the use of the predetermined timing signal having undergone the adjustment by said first adjusting part and measuring the predetermined mark image, correcting the required correction amount for the scan magnification of the modulated light, by comparing the measured value with a reference value; and further adjusting the timing signal, wherein: upon the predetermined mark image forming operation, the timing signal is adjusted in such a manner that the required correction amount for the scan magnification of the modulated light may be obtained in particular in the measurement range of the predetermined mark measurement; and upon the regular image forming operation, the timing signal is adjusted in such a manner that the required correction amount for the scan magnification of the modulated light may be obtained in particular in the predetermined scanning range of the modulated light for the regular image forming operation.