Multicolor image forming apparatus and method
AssigneeFuji Xerox Co., Ltd.
InventorHiromasa Kanno
Life of this patent
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Abstract
The multicolor image forming apparatus according to the present invention comprises openings near the edge of the laser beam scanning start side, near the center, and near the edge of the laser beam scanning end side, on the photoconductor belt. The multicolor image forming apparatus measures time intervals from the horizontal synchronizing signal to the detection of the scanning start-side opening, the center opening, and the scanning end-side opening, respectively. The multicolor image forming apparatus calculates the function indicating the scanning speed at time t along the surface of the photoconductor, to correct the function indicating an image clock frequency at time t.
Claims14
A multicolor image forming apparatus comprising:
- a photoconductor;
- a plurality of laser beam scanners for scanning a plurality of laser beams on a surface of said photoconductor to form a plurality of monochromatic images;
- a multicolor image forming means for forming a multicolor image on said surface of said photoconductor by overlapping said plurality of monochromatic images;
- a scanning speed measuring means for measuring scanning speeds of said plurality of laser beams along said surface of said photoconductor;
- image clock-frequency correcting means for correction image clock frequencies for said plurality of laser beams based on said scanning speeds;
- and
- a plurality of laser beam drivers for driving said plurality of laser beams at said image clock frequencies;
- wherein
- said photoconductor has a second opening provided near a position in which the laser beam is incident substantially at right angles, a first opening provided on a scanning start side of said second opening, and a third opening provided on a scanning end side of said second opening;
- and
- said scanning-speed measuring means has a plurality set of first, second and third opening detectors that detect corresponding laser beams passing through the first, second and third openings.
A multicolor image forming method for forming a multicolor image by overlapping a plurality of monochromatic images one upon another, said plurality of monochromatic images being obtained by scanning a plurality of laser beams on a surface of photoconductor, comprising the steps of:
- measuring a scanning speed of each laser beam alone said surface of said photoconductor;
- correcting an image clock frequency based on a measured scanning speed:
- and driving each laser beam at a corrected image clock frequency;
- wherein
- said photoconductor has a second opening provided near a position in which the laser beam is incident substantially at right angles, a first opening provided on a scanning start side of said second opening, and a third opening provided on a scanning end side of said second opening, and
- the step of measuring a scanning speed of each laser beam along said surface of said photoconductor comprises the steps of detecting the laser beam passing through first, second and third openings provided for each of said laser beam scanners.
A multicolor image forming method for forming a multicolor image by overlapping a plurality of monochromatic images one upon another, said plurality of monochromatic images being obtained by scanning a plurality of laser beams on a surface of photoconductor, comprising the steps of:
- measuring a scanning speed of each laser beam along said surface of said photo conductor;
- correcting an image clock frequency based on a measured scanning speed;
- and
- driving each laser beam at a corrected image clock frequency;
- wherein the step of measuring a scanning speed of each laser beam along said surface of said photoconductor comprises the steps of:
- counting three time differences in detection time between a start of scanning of said laser beam and corresponding detection of said three openings;
- calculating said scanning speed of said laser beam along said surface of said photoconductor based on said three time differences;
- and
- determining a clock frequency to compensate for difference between a calculated scanning speed and a scanning speed as intended in design.
Dependencies are inferred from the claim text.