Color-sensitive currency verifier
First Claim
1. A color-sensitive currency verifier, comprising:
- (a) a plurality of narrowband light sources arranged to project light onto a test area of a specimen bill placed in said currency verifier for verification, each of said light sources emitting light of a unique wavelength when energized;
(b) means for sequentially energizing said light sources, said energizing means including means for energizing one of said light sources to project light of one of said wavelengths onto a predetermined reference area of the bill indicative of bill condition;
(c) a single broadband photodetector optically coupled to said plurality of light sources and operative to produce output signals proportionate to the intensity of light received respectively from said light sources;
(d) color balance means coupled to said light sources and said photodetector for balancing the relative output intensities of said light sources in response to output signals produced by said photodetector;
(e) means for activating said color balance means for a color balancing interval prior to examination of said specimen bill; and
(f) circuit means coupled to said photodetector for determining the authenticity of the specimen bill, said circuit means including(1) means for generating a first reference signal proportionate to the intensity of light received from said reference area;
(2) means operative during a test interval for normalizing output signals produced by said photodetector with respect to a scale factor based upon said first reference signal, whereby test signals produced by said photodetector are normalized with respect to the condition of said specimen bill; and
(3) means for determining the authenticity of the specimen bill based upon said normalized signals,wherein one light source is a reference light source of fixed intensity and the remaining light sources have variable intensity;
said photodetector generates a balancing reference output signal in response to light received from said reference light source during said color balancing interval; and
in which said color balance means includes means for automatically adjusting the intensities of said remaining light sources during said color balancing interval until their corresponding photodetector output signals match said balancing reference output signal.
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Accused Products
Abstract
A color-sensitive currency verifier operating with a plurality of narrowband light sources optically coupled to a single broadband photodetector and including means for automatically balancing the color outputs of the various light sources. Color balancing is accomplished just prior to the examination of a specimen bill. The data samples are taken under the control of a microprocessor and used to authenticate the specimen bill both on the basis of pattern and color information stored in memory. Multiple data samples from a single target area are divided to compensate for soiling condition of the bill, and further compensation for condition of the bill is provided by adjusting the conversion scale factor of an A/D converter on the basis of data samples taken from a reference target area on the surface of the specimen bill before test or data samples are taken.
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Citations
20 Claims
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1. A color-sensitive currency verifier, comprising:
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(a) a plurality of narrowband light sources arranged to project light onto a test area of a specimen bill placed in said currency verifier for verification, each of said light sources emitting light of a unique wavelength when energized; (b) means for sequentially energizing said light sources, said energizing means including means for energizing one of said light sources to project light of one of said wavelengths onto a predetermined reference area of the bill indicative of bill condition; (c) a single broadband photodetector optically coupled to said plurality of light sources and operative to produce output signals proportionate to the intensity of light received respectively from said light sources; (d) color balance means coupled to said light sources and said photodetector for balancing the relative output intensities of said light sources in response to output signals produced by said photodetector; (e) means for activating said color balance means for a color balancing interval prior to examination of said specimen bill; and (f) circuit means coupled to said photodetector for determining the authenticity of the specimen bill, said circuit means including (1) means for generating a first reference signal proportionate to the intensity of light received from said reference area; (2) means operative during a test interval for normalizing output signals produced by said photodetector with respect to a scale factor based upon said first reference signal, whereby test signals produced by said photodetector are normalized with respect to the condition of said specimen bill; and (3) means for determining the authenticity of the specimen bill based upon said normalized signals, wherein one light source is a reference light source of fixed intensity and the remaining light sources have variable intensity;
said photodetector generates a balancing reference output signal in response to light received from said reference light source during said color balancing interval; and
in which said color balance means includes means for automatically adjusting the intensities of said remaining light sources during said color balancing interval until their corresponding photodetector output signals match said balancing reference output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A color-sensitive currency verifer, comprising:
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(a) means for illuminating a specimen bill placed in said currency verifier for verification, said illuminating means including (1) first means for sequentially projecting light of first and second wavelengths onto a reference area; and (2) second means for sequentially projecting light of said first and second wavelengths onto a test area; (b) detection means for detecting light received from said reference and test areas, said detection means including means for generating analog signals proportionate to the intensity of light of the respective wavelengths received from said reference and test areas, said analog signals including a pair of inference signals corresponding to said reference area and a pair of test signals corresponding to said test area; (c) circuit means operative during a test-signal conversion interval for producing a third reference signal proportionate to the greater of said analog reference signals; (d) a variable-reference A/D converter having a signal input coupled to said detection means and a reference input coupled to said circuit means, whereby said A/D converter converts said analog test signals to digital test numbers based upon said third reference signal during said test-signal conversion interval; and (e) digital means for determining the authenticity of the specimen bill based upon said digital test numbers. - View Dependent Claims (10, 11, 12, 13)
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14. A color-sensitive currency verifier, comprising:
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(a) projecting means for sequentially projecting light of first and second wavelengths onto a test area of a specimen bill placed in said currency verifier for verification, said projecting means including means for projecting light of one of said wavelengths onto a reference area of the bill before said sequential projection of light is performed; (b) detection means coupled to said projecting means for detecting light received from said test area, said detection means including means for generating first and second test signals respectively proportionate to the intensity of light of said first and second wavelengths received from said test area, said detection means further including means for detecting light received from said reference area and for generating a first reference signal proportionate to the intensity of light received from said reference area; (c) means for determining a scale factor based upon said first reference signal; (d) means for generating first and second normalized signals respectively proportionate to said first and second test signals by said scale factor, whereby said first and second normalized signals are normalized with respect to the condition of said specimen bill; and (e) means for determining the authenticity of the specimen bill based upon the difference between said first and second normalized signals. - View Dependent Claims (15, 16, 17, 18)
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19. A color-sensitive currency verifier, comprising:
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(a) projecting means for sequentially projecting light of first and second wavelengths onto a test area of a specimen bill placed in said currency verifier for verification, said projecting means including means for projecting light of one of said wavelengths onto a predetermined reference area of the bill indicative of bill condition; (b) detection means coupled to said projecting means for detecting light received from said test area and said reference area, said detection means including (1) means for generating a reference signal proportionate to the intensity of light received from said reference area; and (2) means for generating first and second test signals respectively proportionate to the intensity of light of said first and second wavelengths received from said test area; (c) variable-gain means for generating first and second normalized signals respectively proportionate to said first and second test signals, said variable-gain means including a gain control input; (d) processing means for deriving a gain control signal from said reference signal, said processing means having an output coupled to said gain control input, whereby the gain of said variable-gain means is varied in response to the condition of the bill; and (e) means for determining the authenticity of the specimen bill based upon the difference between said first and second normalized signals. - View Dependent Claims (20)
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Specification