Title:
SCANNING OPTICAL DEVICE EQUIPPED WITH SCANNING SPOT DETECTOR
Document Type and Number:
Japanese Patent JPH02306213
Kind Code:
A
Abstract:
PURPOSE:To obtain a scanning optical device equipped with a scanning spot detector to accurately and stably detect a convergent condition in an arbitrary scanning position in an effective scanning area by utilizing a still ghost image having a character generated in approximately the same position regardless of the rotary position of a rotary polygon mirror. CONSTITUTION:A laser beam from a semiconductor laser 1 receives an conver gent work only in a subscanning direction by a cylindrical lens 3 and linearly image-formed on a mirror surface 4a of a rotary polygon mirror 4. A reflected beam on the mirror surface 4a passes an f-theta lens 5, a spot Ps is formed on a medium surface 6 to be scanned, and a scanning is executed at an equal speed along with the rotation of the polygon mirror 4. The beam to form the spot Ps is diffused and reflected on the medium surface 6 to be scanned, and one part in it forms a ghost image Pg on an element 7 for detecting a ghost image arranged outside the effective scanning area on a scanning line. From the information of the spot diameter and intensity of the ghost image Pg, the focusing condition or convergent condition of the scanning beam spot Ps is decided.
Inventors:
SUZUKI MASAYUKI
Application Number:
JP12736089A
Publication Date:
December 19, 1990
Filing Date:
May 21, 1989
Export Citation:
Assignee:
CANON KK
International Classes:
G02B26/10; B41J2/44; G02B27/00; (IPC1-7): G02B26/10; G03G15/04
Attorney, Agent or Firm:
Kato Kazuo