Claims
- 1. A light scanning device for an electrophotographic printing machine including light deflecting means for deflecting in a scanning mode a light beam outputted by a light source, and an optical system for image-forming said light beam deflected by said light deflecting means, said device comprising:
- means for modulating said light beam in accordance with an image signal;
- image recording means, onto which said light beam is directed by said optical system for recording an image based on said light beam;
- means which is inserted into said optical path at one of convergent and divergent portions of said light beam, for changing a beam spot diameter on said image recording means, said means for changing being a plane-parallel plate.
- 2. A light scanning device as claimed in claim 1, in which a plurality of refractive members are provided in correspondence to different beam spot diameters to be switched.
- 3. A light scanning device as claimed in claim 1, which further comprises a drive unit for moving said refractive member into and out of said optical path.
- 4. An electrophotographic printing machine comprising:
- means for inserting, in response to a print dot density switching instruction from a control unit, a refractive member into the optical path of one of a convergent and a divergent laser beam from a laser beam source to change a beam spot diameter thereof; and
- means for changing the modulating frequency of a modulating means provided for said laser beam source, and means for changing the speed of rotation of a rotary polygon mirror, thereby to change a print dot density.
- 5. An electrophotographic printing machine comprising:
- a plurality of refractive members, each having a unique refractive index; and
- means for modulating a light beam in accordance with an image signal;
- means for inserting, in response to a print dot density switching instruction from a control unit, one of said plurality of refractive members into an optical path of said light beam to change a beam spot diameter on a scanning medium.
- 6. An electrophotographic printing machine comprising:
- means for modulating a light beam in accordance with an image signal;
- a control unit for issuing a plurality of switching instructions each for setting the beam spot diameter of beam spots formed by said light beam to a different value; and
- an inserter responsive to said switching instructions from said control unit for inserting a refractive member having a refractive index selected by each switching instruction.
- 7. A light scanning device as claimed in claim 1, in which said light beam in an optical path between said light source and said light deflecting means one of converges and diverges in a direction perpendicular to the scanning direction and said beam spot diameter on said scanning medium changes in the direction perpendicular to said scanning direction by said refractive member.
- 8. A light scanning device as claimed in claim 1, in which said light beam in an optical path between said light source and said scanning medium one of converges and diverges only in a direction perpendicular to the scanning direction and said beam spot diameter on said scanning medium changes only in the direction perpendicular to said scanning direction by said refractive member.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2-221352 |
Aug 1990 |
JPX |
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Parent Case Info
This is a continuation of application Ser. No. 07/744,722 filed Aug. 14, 1991 abandoned.
US Referenced Citations (10)
Foreign Referenced Citations (5)
Number |
Date |
Country |
57-164759 |
Oct 1982 |
JPX |
58-40742 |
Sep 1983 |
JPX |
61-66465 |
Apr 1986 |
JPX |
62-275214 |
Nov 1987 |
JPX |
63-31270 |
Feb 1988 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
744722 |
Aug 1991 |
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