| 摘要 |
PURPOSE:To obtain an inexpensive photoscanner of simple constitution which obtains distortion-free pictures at a center scanning part and an end part by providing plural light sources at different optical distances to a lens, and driving those light sources selectively according to the angle of deflection of a beam. CONSTITUTION:Light sources 1a and 1b are installed facing a half-mirror 10 so that the optical axes of light beams passed through the half-mirror 10 are coincident with each other. The light beam from the 1st light source 1a and the light beam from the 2nd light source 1b are converged by a converging lens 2 to be projected and reflected light from it is projected upon a photosensitive drum 5. The light beams from the 1st and the 2nd light sources are scanned on the photosensitive drum 5 alternately, and image forming positions of those light beams are as shown by solid lines LA, LB1, and LB2 in a figure. Then, when theta1 and theta2 are as shown by an equation I , errors epsilonA and epsilonB between the image forming positions and the scanning surface of the photosensitive drum 5 are minimized as shown by an equaition II, and the beam spot diameter on the photosensitive drum 5 is made uniform. |
