| 摘要 |
PURPOSE:To uniformly correct a scanning speed and to obtain excellent distortion characteristics and image plane flatness on a light convergence surface over a wide field angle range by interposing a troidal lens and a cylindrical mirror in the optical path from a deflector to the surface of a photosensitive body. CONSTITUTION:The scanning speed is a main scanning direction is corrected by the troidal lens 13 and cylindrical mirror 20 uniformly from the center of a scanning area to both its end parts. Further, the troidal lens 13 which is installed in the optical path of reflection from a polygon mirror 10 corrects a surface tilt error by setting the respective reflecting surfaces of the polygon mirror 10 and the convergence surface of the photosensitive body 30 in conjugate relation on section perpendicular to the deflection surface. Consequently, the scanning speed by the cylindrical mirror 10 is corrected uniformly from the center of the scanning area to both end parts and the excellent distortion characteristics and image plane flatness are obtained on the convergence surface over a wide field angle range. |
