Method and apparatus for beam displacement in a light beam scanner
AssigneeEastman Kodak Company
InventorsMark M. Meyers, James K. Lee, Badhri Narayan, James E. Roddy
Life of this patent
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Abstract
A method and apparatus is provided for line scanning a beam receiving member, wherein a scanning beam is angularly or laterally displaced to compensate for scan line spacing error. The beam is displaced according to error arising from variation (flutter) in the relative motion of the beam and the beam receiving member, or according to error arising from movement of the receiving member while the scanning beam travels to a start of scan position, or both. Embodiments of beam displacement means include a refracting tilt plate, a reflecting tilt plate, a diffracting tilt plate, and a tilt prism.
Claims25
A method for beam scanning of a scan receiving member, comprising the steps of:
- directing a light beam upon means operable by selective orientation for displacing the beam;
- deflecting the light beam so as to effect repeated line scanning of the scan receiving member;
- providing spacing between sequential scan lines, the spacing being subject to error;
- determining the scan line spacing error;
- and
- selectably orienting the beam displacement means in accordance with the determination of the scan line spacing error so as to displace the light beam to compensate for such error.
A method for scan line exposure of a photosensitive member, comprising the steps of:
- directing a laser beam upon means operable by selective orientation for displacing the laser beam;
- deflecting the laser beam so as to effect repeated line scanning of the photosensitive member;
- selectably modulating the laser beam to effect plural line scan exposures of the photosensitive medium;
- providing relative motion in the cross-scan direction between the photosensitive medium and the laser beam to effect spacing between sequential scan line exposures, the spacing being subject to error;
- determining the error in the spacing;
- generating an error correction signal;
- and
- selectably orienting the beam displacement means in accordance with the error correction signal so as to displace the laser beam to compensate for such error.
Apparatus for scanning a light beam upon a scan receiving member, comprising:
- means for generating a light beam;
- means for displacing the light beam, the means being operable by selective orientation thereof;
- means for deflecting the light beam so as to effect plural line scanning of the scan receiving member;
- means for providing spacing between sequential scan lines;
- means for determining scan line spacing error;
- and
- means for selectably orienting the beam displacing means in accordance with the determination of the scan line spacing error so as to displace the light beam to compensate for such error.
Apparatus for scan line exposure of a photosensitive member, comprising:
- means for generating a laser beam;
- means for displacing the laser beam operable by selective orientation thereof;
- means for modulating the laser beam so as to effect exposure of the photosensitive member during selected ones of the line scans;
- means for deflecting the modulated laser beam so as to effect plural line scanning of the photosensitive member;
- means for providing relative motion in the cross-scan direction between the photosensitive member and the laser beam so as to effect a spacing of the scan line exposures, the exposure spacing being subject to error;
- means for determining the spacing error and for generating a spacing error correction signal;
- and
- means for selectably orienting the beam displacement means in accordance with the error correction signal so as to displace the light beam to compensate for the exposure spacing error.
Dependencies are inferred from the claim text.