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US 5,294,945 AGranted
Laser beam optical scanning system and laser printing provided with the laser beam optical scanning system
AssigneeMinolta Camera Kabushiki Kaisha
InventorsKunihiko Omura, Akiyoshi Hamada, Satoru Ono, Hiromu Nakamura
Life of this patent
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Abstract
A laser source unit in which a laser diode is located at a focal point of a Fresnel lens using refraction and diffraction. The laser diode emits a laser beam in accordance with a control signal generated by a driving circuit. The laser diode is driven such that defocus on an image surface caused by a rise in the temperature of the laser diode can be kept in a tolerable degree.
Claims20
A laser beam optical scanning system comprising:
- a laser diode;
- a diffracting member for diffracting and converging a laser beam emitted from the laser diode;
- scanning means for scanning the laser beam converged by the diffracting member on a light receiving surface periodically;
- and
- driving means for driving the laser diode at a duty factor .gamma.;
- wherein the laser beam optical scanning system meets a condition indicated by the following expression:
- ##EQU11## in which expression, .DELTA..gamma. is a variation in the duty factor .gamma., K is a natural constant of the laser diode, f.sub.CO is a focal length of the diffracting member, D.sub.1 is a tolerable maximum diameter of a beam spot on the light receiving surface, D.sub.0 is a diameter of a beam spot on the light receiving surface when the laser diode emits a laser beam with a designed wavelength, and f.sub.H is a focal length of the scanning means.
4 more elements
A laser beam optical scanning system comprising:
- a laser diode;
- a diffracting member for diffracting and converging a laser beam emitted from the laser diode;
- scanning means for scanning the laser beam converged by the diffracting member on a light receiving surface with a specified scanning period T;
- and
- driving means for driving the laser diode continuously for a time a of the scanning period T and intermittently for the rest of the scanning period T;
- wherein the time a meets a condition indicated by the following expression:
- ##EQU12## in which expression, .DELTA..lambda..sub.MAX is a tolerable maximum variation in a wavelength of the laser beam emitted from the laser diode, and K is a natural constant of the laser diode.
4 more elements
A laser printer comprising:
- a photosensitive member;
- a laser diode;
- a diffracting member for diffracting and converging a laser beam emitted from the laser diode;
- scanning means for scanning the laser beam converged by the diffracting member on a surface of the photosensitive member with a specified scanning period T;
- driving means for driving the laser diode to emit a laser beam in accordance with image data for entirely a time of irradiating an image-writing area on the surface of the photosensitive member and to emit a laser beam regularly for a time a within a time of irradiating a non-image-writing area on the surface of the photosensitive member;
- and
- image forming means for developing an image recorded by the laser beam on the surface of the photosensitive member and transferring the developed image onto a sheet;
- wherein the time a of the regular emission of the laser diode is determined such that defocus on the surface of the photosensitive member will be in a tolerable degree.
5 more elements
Dependencies are inferred from the claim text.