Fingerprint detector using ridge resistance sensing array
First Claim
1. A fingerprint detector comprising:
- sensing array means for translating a skin resistance of a fingertip into a sample trajectory signal as the fingertip is moved relative to the sensing array means, said sample trajectory signal being produced by a curvilinear trajectory formed by ridges and valleys of the fingertip and representing electrical conductance changes in the skin resistance of the fingertip associated with a profile of its ridges and valleys, said sensing array means including at least one sensor positioned for contacting the fingertip and allowing relative movement between the fingertip and the sensor, said sensor producing said sample trajectory signal corresponding to the skin resistance of the ridges and valleys as the fingertip and the sensing array means are moved relative to one another;
sampling means, coupled to said sensing array means, for quantizing said sample trajectory signal; and
processing means, coupled to said sampling means, for comparing said sample trajectory signal with a reference trajectory signal and producing a verification signal related to a probability that the fingertip generated both the sample trajectory signal and the reference trajectory signal.
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Abstract
A fingerprint detector that uses a skin resistance sensing array for producing a sample trajectory signal when a fingertip is moved across the sensing array surface. The sample trajectory signal represents the electrical conductance changes in the resistance of ridges and valleys of the fingertip. The fingerprint detector also includes a sampling circuit coupled to a processor. In addition, a technique is disclosed for detecting and verifying a fingerprint by moving a fingertip relative to the skin resistance sensing array. The sample trajectory signal produced is translated into a digital signal by the sampling circuit. The processor receives the digital sample trajectory signal for comparison with a known reference trajectory signal. The processor produces a verification signal if a threshold probability that the same fingertip generated both signals is exceeded. The reference trajectory signal is stored in a memory integrated into the device, or is provided from an external storage device through a data interface.
134 Citations
20 Claims
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1. A fingerprint detector comprising:
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sensing array means for translating a skin resistance of a fingertip into a sample trajectory signal as the fingertip is moved relative to the sensing array means, said sample trajectory signal being produced by a curvilinear trajectory formed by ridges and valleys of the fingertip and representing electrical conductance changes in the skin resistance of the fingertip associated with a profile of its ridges and valleys, said sensing array means including at least one sensor positioned for contacting the fingertip and allowing relative movement between the fingertip and the sensor, said sensor producing said sample trajectory signal corresponding to the skin resistance of the ridges and valleys as the fingertip and the sensing array means are moved relative to one another; sampling means, coupled to said sensing array means, for quantizing said sample trajectory signal; and processing means, coupled to said sampling means, for comparing said sample trajectory signal with a reference trajectory signal and producing a verification signal related to a probability that the fingertip generated both the sample trajectory signal and the reference trajectory signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A fingerprint detector comprising:
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(a) a skin resistance sensing array for contacting a fingertip and translating a skin resistance of ridges and valleys of the fingertip into a sample trajectory signal as the fingertip and the skin resistance sensing array are moved relative to one another, said sample trajectory signal being produced by a curvilinear trajectory formed by ridges and valleys of the fingertip and representing electrical conductance changes in the skin resistance of the fingertip associated with a profile of its ridges and valleys with respect to time, said skin resistance sensing array including; (i) an insulating layer having a first side and a second side; (ii) a conducting layer formed on said first side of said insulating layer having a top surface opposed to said first side, said conducting layer having a plurality of holes for exposing said insulating layer; (iii) an array of conducting wires extending from said second side of said insulating layer and through said holes, each conducting wire being centered within each said hole; and
said array of conducting wires being flushly aligned with the top surface of said conducting layer;(b) a multiplexer coupled to said skin resistance sensing array for selectively switching between each conducting wire of said skin resistance sensing array; (c) an analog to digital converter coupled to said multiplexer for generating a digital bit stream representing said sample trajectory signal; and (d) a processor coupled to said analog to digital converter for comparing said sample trajectory signal with a reference trajectory signal and producing a verification signal related to a probability that the fingertip generated both the sample trajectory signal and the reference trajectory signal. - View Dependent Claims (14, 15, 16)
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17. A method for detecting and verifying a fingerprint, said method comprising the steps of:
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providing a skin resistance sensing array; moving a fingertip relative to the skin resistance sensing array, said skin resistance sensing array translating skin resistance of a fingertip into a sample trajectory signal, said sample trajectory signal being produced by a curvilinear trajectory formed by ridges and valleys of the fingertip and representing electrical conductance changes in the skin resistance of the fingertip associated with a profile of its ridges and valleys; correlating said sample trajectory signal with a reference trajectory signal; and producing a verification signal related to the probability that the fingertip generated both the sample trajectory signal and the reference trajectory signal. - View Dependent Claims (18, 19, 20)
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Specification