Patent ID: 7190383

Claim:
A misalignment detector in an image forming apparatus in which a latent image is formed on an image carrier by using a plurality of laser beams, the misalignment detector detects a position-shift of each laser beam, comprising: a two-dimensional image sensor configured to read a position detection pattern that is formed on an image carrier; a light source that outputs light; a synthesizing unit configured to refract input light from the light source and to pass the light of the light source so as to illuminate the position detection pattern, and collects and reflects a light reflected from the position detection pattern; and a focusing unit that focuses the light reflected from the synthesizing unit on the image sensor; an adding unit that adds up image data of the two-dimensional image sensor in any one of the main scanning direction and the secondary scanning direction; and a peak-position detector that detects a peak position in one-dimensional data that is output by the adding unit, wherein the position detection pattern includes a plurality of lines that are parallel to each other.