Patent ID: 7227564

Claim:
An image forming apparatus capable of successively forming images on a first surface and a second surface of a transfer material and fixing the images, comprising: an image carrier; a light scanning device that forms a latent image on said image carrier by scanning a light beam based on image data and in accordance with an image clock; a horizontal synchronization signal detecting device that detects from the light beam a horizontal synchronization signal for controlling a write start position of the latent image on the image carrier; and a pulse adjusting device that sets a second number of pulses of the image clock corresponding to a distance from said horizontal synchronization signal detecting device to the write start position of the latent image during image formation on the second surface, to a number of pulses different from a first number of pulses of the image clock corresponding to a distance from said horizontal synchronization signal detecting device to the write start position of the latent image during image formation on the first surface, based on the first number of pulses of the image clock during image formation on the first surface, in accordance with an expansion/contraction ratio of the transfer material after fixing of the image on the first surface, wherein said pulse adjusting device adjusts the second number of pulses of the image clock so as to be 1/(1+X/100) of the first number of pulses of the image clock, where X represents in percentage the expansion/contraction ratio of the transfer material after fixing the image on the first surface, and is positive when the transfer material expands and negative when the transfer material contracts.