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US 5,671,069 AGranted
Pixel clock generator
AssigneeFuji Xerox Co., Ltd.
InventorKouichi Kodama
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AssigneeFuji Xerox Co., Ltd.
InventorKouichi Kodama
Estimating the term…
A pixel clock generator in which the frequency of a pixel clock signal is changed over for every scanning face prior to start of image record scanning, comprises a first scanning time detection circuit for detecting scanning period of time from the start of image scanning to the end of the image scanning; a reference clock signal generation circuit for generating a reference clock signal to make the frequency of the reference clock signal variable; a number-of-pixel-clocks setting circuit for setting the number of pixel clocks corresponding to forecast scanning time; a second scanning time detection circuit for counting the pixel clocks generated based the reference clock signal by the number set by the number-of-pixel-clocks setting circuit to detect the scanning time corresponding to the forecast scanning time; a comparison circuit for comparing the time detected by the first scanning time detection circuit with the time detected by the second scanning time detection circuit to obtain a comparison result; a correction data storage circuit for storing data for correcting the second scanning time for every scanning face; a renewal circuit for renewing the correction data of the correction data storage circuit according to the result of the comparison result; and a correction circuit to perform variable control by correcting the frequency of the reference clock signal outputted from the reference clock signal generator according to the data renewed by the renewal circuit.
A pixel clock generator in which the frequency of a pixel clock signal is changed over for every scanning face prior to start of image record scanning, said generator comprising:
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Detection, control or error compensation of scanning velocity or position: in main scanning direction, e.g. synchronisation of line start or…
Using oscillating or rotating mirrors: for the main-scan only
Scanning arrangements , i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing…:…
Arrangements for positioning elements within a head: positioning method
Term ended 5 Apr 2015 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to a pixel clock generator for a copying machine, a laser printer, or the like, and particularly to a pixel clock generator in which it is possible to correct the displacement of pixels in the scanning direction caused by variations in the scanning period, in the work accuracy and in the rotational speed of an optical deflector for a copying machine, a laser printer, or the like.
2. Description of the Related Art
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate (an) embodiment(s) of the invention and, together with the description, serve to explain the objects, advantages and principles of the invention. In the drawings,
FIG. 1 is a block diagram showing the schematic configuration of a pixel clock generator according to an embodiment of the present invention;
FIGS. 2A to 2M are time charts showing the operation of the pixel clock generator of FIG. 1;
Referring to the drawings, an embodiment of the present invention will be described below in detail.
FIG. 1 is a block diagram showing the schematic configuration of an embodiment of the pixel clock generator according to the present invention, and FIGS. 2A to 2M are time charts showing the circuit operation of the pixel clock generator.
In FIG. 1, a rotary polyhedron mirror 1 is rotated by an electric motor 2 to scan a laser beam 28 emitted from a laser oscillator 21. Detecting the laser beam, an optical sensor 3 supplies the laser beam detection signal to an amplifier 4 which amplifies this detection signal to output a rectangular scanning start detection signal (hereinafter referred to as "SOS signal") (a). When an optical sensor 6 detects the laser beam, the detection output of the optical sensor 6 is amplified by an amplifier 7 so as to provide scanning end detection signal (hereinafter referred to as "EOS signal") (b).