Patent ID: 8199179
Filing Date: 2012-06-12
Classification: G02B,H04N

Abstract:
1. A scanning unit that scans a scanning target surface by using light fluxes, the scanning unit comprising: a light source having a plurality of surface-emitting lasers each emitting a light beam; a coupling lens that receives the light beams from the light source and renders the light beams as substantially parallel light; an aperture that receives the parallel light and defines a diameter of the parallel light thereby obtaining a diameter-defined parallel light; an image forming lens that receives the diameter-defined parallel light and forms an image in a sub-scanning direction; and an optical deflector that is arranged close to a focal point of the image forming lens, and that receives light beams of the image and deflects the light beams for scanning a target surface, wherein a focal length of the image forming lens in the sub-scanning direction is smaller than an optical path length between the image forming lens and the aperture, and a beam diameter in the sub-scanning direction is equal to or smaller than a beam diameter in the main scanning direction but greater than a distance between adjacent scanning lines.