Electronic imager using an impedance sensor grid array and method of making
First Claim
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1. A fingerprint impedance sensor, comprising:
- a plurality of substantially parallel drive lines configured to transmit a signal to a proximally located finger having fingerprint features to be sensed;
a plurality of substantially parallel pickup lines configured to receive a resultant signal and oriented substantially perpendicular to the drive lines and physically separated from the drive lines on a different layer by a dielectric having a substantially fixed thickness and located between the drive lines and pickup lines to form a two dimensional array of intrinsic electrode pairs about the drive and pickup crossover locations to define an active sensing area where the fingerprint features are sensed;
active circuitry including one of a plurality of buffers and a plurality of analog switches that multiplex the plurality of pickup lines into one or more differential amplifiers, wherein each buffer or switch receives the resultant signal from corresponding selected pickup lines, and a plurality of switches configured to shut down power simultaneously or switch to a low impedance all other pickup lines that are not selected, wherein the active circuit is located substantially peripheral to the active sensing area about the beginning or end of the pickup lines; and
a drive circuit located substantially peripheral to the active sensing area about the beginning or end of a drive line;
wherein the drive lines and pickup lines are configured to make the pickup crossover locations within the active sensing area sensitive to proximal electric fields and to detect signals proportional to impedance differences between the ridge and valley features of a proximally located finger for purposes of acquiring a fingerprint image; and
wherein the drive lines and pickup lines are configured on a single flexible dielectric substrate that is folded back to back with the single flexible dielectric substrate interior to a fold in such a way that the single flexible dielectric substrate becomes an insulating layer separating the drive and pickup lines.
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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.
720 Citations
30 Claims
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1. A fingerprint impedance sensor, comprising:
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a plurality of substantially parallel drive lines configured to transmit a signal to a proximally located finger having fingerprint features to be sensed; a plurality of substantially parallel pickup lines configured to receive a resultant signal and oriented substantially perpendicular to the drive lines and physically separated from the drive lines on a different layer by a dielectric having a substantially fixed thickness and located between the drive lines and pickup lines to form a two dimensional array of intrinsic electrode pairs about the drive and pickup crossover locations to define an active sensing area where the fingerprint features are sensed; active circuitry including one of a plurality of buffers and a plurality of analog switches that multiplex the plurality of pickup lines into one or more differential amplifiers, wherein each buffer or switch receives the resultant signal from corresponding selected pickup lines, and a plurality of switches configured to shut down power simultaneously or switch to a low impedance all other pickup lines that are not selected, wherein the active circuit is located substantially peripheral to the active sensing area about the beginning or end of the pickup lines; and a drive circuit located substantially peripheral to the active sensing area about the beginning or end of a drive line; wherein the drive lines and pickup lines are configured to make the pickup crossover locations within the active sensing area sensitive to proximal electric fields and to detect signals proportional to impedance differences between the ridge and valley features of a proximally located finger for purposes of acquiring a fingerprint image; and wherein the drive lines and pickup lines are configured on a single flexible dielectric substrate that is folded back to back with the single flexible dielectric substrate interior to a fold in such a way that the single flexible dielectric substrate becomes an insulating layer separating the drive and pickup lines. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification
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Current AssigneeIDEX Biometrics ASA
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Original AssigneePicofield Technologies, Inc.
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InventorsBenkley, Fred G. III
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Primary Examiner(s)NGUYEN, LUONG TRUNG
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Application NumberUS12/688,790Publication NumberTime in Patent Office1,187 DaysField of SearchNoneUS Class Current348/294CPC Class CodesG06V 40/1306 non-optical, e.g. ultrasoni...
