Document detection apparatus
First Claim
1. An apparatus for detecting the location of a sheet, comprising:
- a platen for supporting the sheet and providing a backing for scanning the sheet, said platen including a first optically detectable pattern having a first predetermined frequency, and a second optically detectable pattern superimposed thereon, having a second predetermined frequency, with the first predetermined frequency being harmonically unrelated to said second predetermined frequency;
a sensor, in communication with said platen, for providing data indicative of the sheet, the first optically detectable pattern and the second optically detectable pattern;
means for producing relative movement between said sheet and said sensor; and
a processor, in communication with said sensor, .for discriminating the first optically detectable pattern and second optically detectable patterns on said platen backing surface from said sheet according to the data from said sensor so as to determine the location of the sheet on said platen.
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Accused Products
Abstract
A scanning background member is provided with two or more superimposed line sets or density patterns of having frequencies unrelated to each other that can be detected by a background detection circuit of a document scanner. The multifrequency edge detection arrangement may also control various image movement and modification features that CCD or full-width array sensors may be used to produce accurate edge detection with minimum processing hardware. Detection of differing frequency density patterns or line sets on the scanning background permits the scanner to precisely determine the edges and cutout areas of a scanned original sheet, while employing minimized hardware and software processing requirements. Frequency-related or other edge detection errors that may result from image patterns, moire effects or other inherent, problematic or random sheet/image conditions may be greatly reduced if not eliminated. The edge detection system of the present invention offers improved performance over repetitive symbol and other scanning background schemes which may require greater processing hardware and software while suffering from lower edge resolution and/or higher edge detection error probabilities.
117 Citations
14 Claims
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1. An apparatus for detecting the location of a sheet, comprising:
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a platen for supporting the sheet and providing a backing for scanning the sheet, said platen including a first optically detectable pattern having a first predetermined frequency, and a second optically detectable pattern superimposed thereon, having a second predetermined frequency, with the first predetermined frequency being harmonically unrelated to said second predetermined frequency; a sensor, in communication with said platen, for providing data indicative of the sheet, the first optically detectable pattern and the second optically detectable pattern; means for producing relative movement between said sheet and said sensor; and a processor, in communication with said sensor, .for discriminating the first optically detectable pattern and second optically detectable patterns on said platen backing surface from said sheet according to the data from said sensor so as to determine the location of the sheet on said platen. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A printing machine having an apparatus for detecting the location of a sheet, comprising:
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a platen for supporting the sheet and providing a backing for a scanning the sheet, said platen including a first optically detectable pattern, having a first predetermined frequency, and a second optically detectable pattern superimposed thereon, having a second predetermined frequency, with the first predetermined frequency being harmonically unrelated to said second predetermined frequency; a sensor, in communication with said platen, for providing data indicative of the sheet, and the first optically detectable pattern and the second optically detectable pattern; means for producing relative movement between said sheet and said sensor; and a processor, in communication with said sensor, for discriminating the first optically detectable pattern and second optically detectable patterns on said platen backing surface from said sheet according to the data from said sensor so as to determine the location of the sheet on said platen. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification