PHOTOSCANNER,申请号JP19900221352-传众专利搜索

PHOTOSCANNER

申请公布号：JPH04104216(A)

申请号：JP19900221352

申请日期：1990.08.24

申请公布日期：1992.04.06

申请人：

HITACHI KOKI CO LTD;HITACHI LTD

发明人：MOCHIZUKI KENJI;SAITO SUSUMU;NISHINO SHINICHI;KIKUCHI TAKAHIRO;ARIMOTO AKIRA

分类号：G02B26/12;G02B26/10;G02B27/00;G03G15/04;H04N1/04

主分类号：G02B26/12

摘要：PURPOSE:To vary the diameter of a recording dot by a simple function over a wide range by inserting a refractive index member into an optical path of a converged or diverged beam and varying the diameter of a beam spot on a scanned medium. CONSTITUTION:The beam 7 projected by a light source 1 is collimated by a collimator lens 2 into a parallel beam, which is reduced by a cylindrical lens 3 only in a scanning vertical direction to form a line image nearby the reflecting surface of a rotary polygon mirror 4; and an Ftheta lens 5 is an anamorphic aspherical lens. The scanning direction is so arranged that an infinite distance point and a photosensitive drum surface are in optically conjugate relation; and the vertical scanning direction is so arranged that the periphery of the reflecting surface of the rotary polygon mirror and photosensitive drum surface are in optically conjugate relation. The line image nearby the reflecting surface of the rotary polygon mirror is formed on the photosensitive drum surface. Namely, the parallel plane plate 8 is interposed between the cylindrical lens 3 and rotary polygon mirror 4. The diameter of the beam spot is switched according to the recording dot density switching command of the controller of a laser printer, etc. Consequently, the scanning spot diameter is easily varied and print dot density varies over a wide range.