Color image reading apparatus with white balance system for controlling the intensity of a light source illuminating a color document
First Claim
1. A color image reading apparatus comprising:
- a light source, the intensity of light produced thereby varying in accordance with the amount of power supplied thereto;
reading means for photoelectrically reading a color document illuminated by said light source a plurality of times and for generating a plurality of color component signals representing the color document a different one of said plurality of color component signals being generated during each reading of said color document;
a reference area which can be illuminated by said light source;
means for causing said reading means to read said reference area illuminated by said light source prior to reading the color document to generate a plurality of reference color component signals; and
means for controlling the amount of power supplied to said light source during each reading of said color document by said reading means in accordance with the plurality of reference color component signals generated by said reading means.
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Accused Products
Abstract
In a color image reading apparatus, a CCD line image sensor reads a color document illuminated by a light source three times in succession through red, green and blue filters to produce red, green and blue color component signals. Prior to reading the color document, the line sensor reads a standard reference area illuminated by the light source to produce red, green and blue reference color component signals. The intensity of the light source is adjusted so that the level of the reference color component signals is equal to a predetermined value. Red, green and blue control signals corresponding to the light intensities at which the levels of the red, green and blue reference color component signals are equal to the predetermined value are stored. These stored control signals are used to control the intensity of the light source while the line sensor reads the document to produce the red, green and blue color component signals. The standard reference area may be a white area, or may be made up of separate red, green and blue areas.
41 Citations
9 Claims
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1. A color image reading apparatus comprising:
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a light source, the intensity of light produced thereby varying in accordance with the amount of power supplied thereto; reading means for photoelectrically reading a color document illuminated by said light source a plurality of times and for generating a plurality of color component signals representing the color document a different one of said plurality of color component signals being generated during each reading of said color document; a reference area which can be illuminated by said light source; means for causing said reading means to read said reference area illuminated by said light source prior to reading the color document to generate a plurality of reference color component signals; and means for controlling the amount of power supplied to said light source during each reading of said color document by said reading means in accordance with the plurality of reference color component signals generated by said reading means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification