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Document reading apparatus and an image formation apparatus

  • US 20060203306A1
  • Filed: 02/21/2006
  • Published: 09/14/2006
  • Est. Priority Date: 02/28/2005
  • Status: Active Grant
First Claim
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1. A document reading apparatus, comprising:

  • a scanner for scanning a document;

    a power supply unit for providing operating voltages to the scanner in a waiting mode for reading the document, and suspending the operating voltages in a pause mode;

    an input unit for inputting operation directions to the scanner;

    an energy-saving control unit for switching the power supply unit to the pause mode if there is no operation direction being issued and the waiting mode lasts a predetermined period, and for switching the power supply unit to the waiting mode if there is an operation direction being issued during the pause mode; and

    a clock unit for counting time and for generating time data;

    wherein the scanner includes an image sensor for converting image light reflected from the document into an image signal;

    an optical unit for projecting the image light of the document onto the image sensor;

    an image signal processing unit for converting the image signal into digital image data;

    a reference white plate;

    an output compensation unit for updating digital conversion parameters including an image signal amplification gain of the image signal processing unit so that the image data of the reference white plate projected onto the image sensor by the optical unit and converted by the image signal processing unit may become a proper value; and

    an output compensation control unit for controlling the output compensation, wherein the time data of the clock unit are read when an operating voltage for reading the document is provided pursuant to the power supply unit being switched to the waiting mode;

    whether an elapsed time from the last operation time held in a non-volatile memory is equal to or greater than a predetermined value is determined;

    if the determination is affirmative, the digital conversion parameters are updated by the output compensation unit, the updated digital conversion parameters are stored in the non-volatile memory, and the last operation time is replaced with the present time data; and

    if the determination is negative, the digital conversion parameters stored in the non-volatile memory are loaded in the image signal processing unit.

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