Patent ID: 6924830

Claim:
A color imaae forming apparatus, comprising: a first image forming device including a first scanning optical device to form a first image and a first developing device to develop the first image into a first color toner image; and a second image forming device including a second scanning optical device to form a second image and a second developing device to develop the second image into a second color toner image; wherein each of the first and second optical devices comprises: a light source which emits a light beam; a deflector which deflects the light beam so as to scan an image forming surface in a main scanning direction with the light beam; a plurality of lenses provided between the deflector and the image forming surface to focus the deflected light on the image forming surface, wherein each of the plurality of lenses has a length along the main scanning direction; and a lens positioning device to position at least one lens of the plurality of lenses rotatably around an axis parallel to the length of the at least one lens to adjust a characteristic of a scan line image in an adjustment process; wherein a characteristic of a first scan line image and a characteristic of a second scan line image substantially become the same when at least one of the lenses is rotated around the axis parallel to the length of the lens; and wherein the positioning device of each of the first and second optical devices allows the respective at least one rotatable lenses to be rotatable so as to make deviations between the respective line images and the desired line smaller than 200 μm.