Electronic imager using an impedance sensor grid array and method of making
First Claim
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1. An fingerprint impedance sensor, comprising:
- a plurality of substantially parallel drive lines;
a plurality of substantially parallel pickup lines oriented substantially perpendicular to the drive lines and physically separated from the drive lines by a substantially incompressible dielectric located between the drive lines and pickup lines to form a plurality of impedance sensitive crossover locations where a pickup line crosses a drive line; and
circuitry that includes a signal generator connected to the drive lines, and configured to;
sequentially activate each of the drive lines by transmitting a signal to each of the drive lines, one at a time, and grounding the remaining drive lines while the signal is being transmitted to the one activated drive line to thereby cause an electric field to radiate from the one activated drive line toward the pickup line at each of the impedance sensitive crossover locations formed by the activated drive line,for each drive line that is activated, sequentially measure an amount of the electric field on each of the pickup lines at each of the impedance sensitive crossover locations and ground the remaining pickup lines while the electric field is being measured at the one pickup line, anddistinguish between different surface features of a proximally located finger at each of one or more of the impedance sensitive crossover locations based on the amount of the electric field measured at the crossover location.
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Abstract
An novel impedance sensor is provided having a plurality of substantially parallel drive lines configured to transmit a signal into a surface of a proximally located object, and also a plurality of substantially parallel pickup lines oriented substantially perpendicular to the drive lines and separated from the pickup lines by a dielectric to form intrinsic electrode pairs that are impedance sensitive at each of the drive and pickup crossover locations.
716 Citations
14 Claims
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1. An fingerprint impedance sensor, comprising:
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a plurality of substantially parallel drive lines; a plurality of substantially parallel pickup lines oriented substantially perpendicular to the drive lines and physically separated from the drive lines by a substantially incompressible dielectric located between the drive lines and pickup lines to form a plurality of impedance sensitive crossover locations where a pickup line crosses a drive line; and circuitry that includes a signal generator connected to the drive lines, and configured to; sequentially activate each of the drive lines by transmitting a signal to each of the drive lines, one at a time, and grounding the remaining drive lines while the signal is being transmitted to the one activated drive line to thereby cause an electric field to radiate from the one activated drive line toward the pickup line at each of the impedance sensitive crossover locations formed by the activated drive line, for each drive line that is activated, sequentially measure an amount of the electric field on each of the pickup lines at each of the impedance sensitive crossover locations and ground the remaining pickup lines while the electric field is being measured at the one pickup line, and distinguish between different surface features of a proximally located finger at each of one or more of the impedance sensitive crossover locations based on the amount of the electric field measured at the crossover location. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification