Color image forming apparatus having means for properly superimposing image colors on each other

An image forming apparatus comprising:

• scanner means for scanning each line of a predetermined color image and for generating an image data representing the predetermined color image by means of a laser beam, the predetermined color image comprising a plurality of image colors;
• an optical recording system including a rotating polygon mirror which deflects the laser beam;
• a body system including a rotating photosensitive body onto which the laser beam deflected by the rotating polygon mirror is radiated so as to form a latent image corresponding to the predetermined color image;
• buffer means for storing at least three lines of the image data, a first line of image data being stored twice;
• and
• switch means, coupled to the body system, for determining, based on a time difference between a position detecting signal and a position signal, whether or not the first line of image data is output twice to the body system, and for outputting each line of image data to said body system so that the image colors can be approximately superimposed on each other, the position detecting signal indicating that the laser beam is ready to be radiated onto the photosensitive body of the body system, the position signal indicating that the photosensitive body is located at a position where the laser beam can be properly radiated thereon, and the position detecting signal being asynchronous with the position signal.