Patent ID: 7777776
Filing Date: 2010-08-17
Classification: H04N

Abstract:
1. An image forming apparatus having a scanning optical device for scanning an image carrier with a laser beam emitted from a laser beam source by a polygon minor based on input image data so as to form an electrostatic latent image on the image carrier, the image forming apparatus comprising: a storing unit configured to store, so that pixels are formed at a constant interval in each of a plurality of divided segments in a scanning direction of the laser beam, frequency data of a clock signal for modulating the image data associated with each of the divided segments and data of a plurality of modulation points for modulating the frequency while the laser beam scans the image carrier once; a frequency modulation unit configured to modulate a frequency of the clock signal based on the frequency data and the data of the modulation points; and a laser beam source driving unit configured to emit the laser beam from the laser beam source based on the input image data and the signal, the frequency of which is modulated by the frequency modulation unit, wherein the storing unit stores the data of the plurality of modulation points so that a modulation point of the frequency while a first scan line is formed does not overlap with a modulation point of the frequency while a second scan line adjacent to the first scan line is formed, in a direction perpendicular to a scanning direction of the laser beam; and wherein the frequency modulation unit modulates the frequency based on the data of the modulation points different between the first scan line and the second scan line.