Finger biometric sensor with sensor electronics distributed over thin film and monocrystalline substrates and related methods

• US 20050110103A1
• Filed: 09/24/2004
• Published: 05/26/2005
• Est. Priority Date: 09/24/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: AuthenTec Incorporated (Apple Inc.)
• Inventors: Setlak, Dale R.
• Granted Patent: US 7,616,786 B2
• Time in Patent Office: Days
• US Class Current: 257/414
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing

Abstract

A finger biometric sensor may include a thin film substrate, a thin film transistor (TFT) layer on the thin film substrate, and an array of electric field sensing electrodes adjacent the TFT layer for receiving a finger adjacent thereto. The TFT layer may include a plurality of TFTs defining a respective TFT amplifier stage for each electric field sensing electrode. The sensor may further include a finger excitation electrode adjacent the array of electric field sensing electrodes, and at least one integrated circuit adjacent the thin film substrate. The integrated circuit may include a monocrystalline substrate and processing circuitry adjacent the monocrystalline substrate and connected to the TFT amplifier stages.

Claims

1. A finger biometric sensor comprising:

a thin film substrate;

a thin film transistor (TFT) layer on said thin film substrate;

an array of electric field sensing electrodes adjacent said TFT layer for receiving a finger adjacent thereto;

said TFT layer comprising a plurality of TFTs defining a respective TFT amplifier stage for each electric field sensing electrode;

a finger excitation electrode for applying an electric field to the finger; and

at least one integrated circuit adjacent said thin film substrate comprising

a monocrystalline substrate, and

processing circuitry adjacent said monocrystalline substrate and connected to said TFT amplifier stages.

2. The finger biometric sensor of claim 1 wherein said TFT layer further comprises a plurality of TFT switching circuits each connected between the output of a respective TFT amplifier stage and said processing circuitry;

said at least one integrated circuit further comprising an addressing circuit adjacent said monocrystalline substrate for selectively operating said TFT switching circuits.

3. The finger biometric sensor of claim 2 wherein said addressing circuit selectively operates said TFT switching elements to provide time domain multiplexing.

4. The finger biometric sensor of claim 2 wherein said addressing circuit selectively operates said TFT switching elements to provide frequency domain multiplexing.

5. The finger biometric sensor of claim 2 wherein said TFT switching elements are arranged in rows and columns;

and wherein said addressing circuit sequentially operates at least one of rows and columns of said TFT switching circuits.

6. The finger biometric sensor of claim 1 wherein each TFT amplifier stage comprises a differential TFT pair;

and wherein said at least one integrated circuit further comprises a plurality of gain amplifier stages adjacent said monocrystalline substrate each connected between a respective TFT amplifier stage and said processing circuitry.

7. The finger biometric sensor of claim 6 wherein each gain amplifier stage is connected in a feedback loop to its respective TFT amplifier stage.

8. The finger biometric sensor of claim 1 wherein said at least one integrated circuit further comprises an excitation drive amplifier adjacent said monocrystalline substrate for driving said finger excitation electrode with an alternating current (AC) signal.

9. The finger biometric sensor of claim 1 wherein said at least one integrated circuit further comprises an addressing circuit for selectively operating said TFT amplifier stages.

10. The finger biometric sensor of claim 1 further comprising a respective shield electrode associated with each of said electric field sensing electrodes for shielding each electric field sensing electrode from adjacent field sensing electrodes.

11. The finger biometric sensor of claim 10 wherein each TFT amplifier stage drives said shield electrode for its respective electric field sensing electrode.

12. The finger biometric sensor of claim 1 wherein said processing circuitry comprises:

a demodulator for demodulating signals from said TFT amplifier stages; and

an analog-to-digital converter (ADC) downstream from said demodulator.

13. The finger biometric sensor of claim 1 wherein said array of electric field sensing electrodes generate finger biometric data based upon a sliding finger placement.

14. The finger biometric sensor of claim 1 wherein said array of electric field sensing electrodes generate finger biometric data based upon a stationary fingerprint placement.

15. A finger biometric sensor comprising:

a thin film substrate;

a thin film transistor (TFT) layer on said thin film substrate;

an array of electric field sensing electrodes for receiving a finger adjacent thereto;

said TFT layer comprising a plurality of TFTs defining a respective TFT amplifier stage for each electric field sensing electrode, and a plurality of TFT switching circuits each connected between the output of a respective TFT amplifier stage and said processing circuitry;

a finger excitation electrode for applying an electric field to the finger; and

at least one integrated circuit adjacent said thin film substrate comprising

a monocrystalline substrate,

an addressing circuit adjacent said monocrystalline substrate for selectively operating said TFT switching circuits,

an excitation drive amplifier adjacent said monocrystalline substrate for driving said finger excitation electrode with an alternating current (AC) signal, and

processing circuitry adjacent said monocrystalline substrate and connected to said TFT amplifier stages.

16. The finger biometric sensor of claim 15 wherein said addressing circuit selectively operates said TFT switching elements to provide time domain multiplexing.

17. The finger biometric sensor of claim 15 wherein said addressing circuit selectively operates said TFT switching elements to provide frequency domain multiplexing.

18. The finger biometric sensor of claim 15 wherein said TFT switching elements are arranged in rows and columns;

and wherein said addressing circuit sequentially operates at least one of rows and columns of said TFT switching circuits.

19. The finger biometric sensor of claim 15 wherein each TFT amplifier stage comprises a differential TFT pair;

and wherein said at least one integrated circuit further comprises a plurality of gain amplifier stages adjacent said monocrystalline substrate each connected between a respective TFT amplifier stage and said processing circuitry.

20. The finger biometric sensor of claim 19 wherein each gain amplifier stage is connected in a feedback loop to its respective TFT amplifier stage.

21. The finger biometric sensor of claim 15 further comprising a respective shield electrode associated with each of said electric field sensing electrodes for shielding each electric field sensing electrode from adjacent field sensing electrodes.

22. The finger biometric sensor of claim 15 wherein said array of electric field sensing electrodes generate finger biometric data based upon a sliding finger placement.

23. The finger biometric sensor of claim 15 wherein said array of electric field sensing electrodes generate finger biometric data based upon a stationary fingerprint placement.

24. A finger biometric sensor comprising:

a thin film substrate;

a thin film transistor (TFT) layer on said thin film substrate;

an array of electric field sensing electrodes adjacent said TFT layer for receiving a finger adjacent thereto;

said TFT layer comprising a plurality of TFTs defining a respective TFT amplifier stage for each electric field sensing electrode, and each TFT amplifier stage comprising a differential TFT pair; and

at least one integrated circuit adjacent said thin film substrate comprising

a monocrystalline substrate,

processing circuitry adjacent said monocrystalline substrate, and

a plurality of gain amplifier stages adjacent said monocrystalline substrate each connected between a respective TFT amplifier stage and said processing circuitry.

25. The finger biometric sensor of claim 24 wherein said TFT layer further comprises a plurality of TFT switching circuits each connected between the output of a respective TFT amplifier stage and said processing circuitry;

said at least one integrated circuit further comprising an addressing circuit adjacent said monocrystalline substrate for selectively operating said TFT switching circuits.

26. The finger biometric sensor of claim 25 wherein said addressing circuit selectively operates said TFT switching elements to provide time domain multiplexing.

27. The finger biometric sensor of claim 25 wherein said addressing circuit selectively operates said TFT switching elements to provide frequency domain multiplexing.

28. The finger biometric sensor of claim 25 wherein said TFT switching elements are arranged in rows and columns;

and wherein said addressing circuit sequentially operates at least one of rows and columns of said TFT switching circuits.

29. The finger biometric sensor of claim 24 wherein each gain amplifier stage is connected in a feedback loop to its respective TFT amplifier stage.

30. The finger biometric sensor of claim 24 further comprising a respective shield electrode associated with each of said electric field sensing electrodes for shielding each electric field sensing electrode from adjacent field sensing electrodes.

31. The finger biometric sensor of claim 24 wherein said array of electric field sensing electrodes generate finger biometric data based upon a sliding finger placement.

32. The finger biometric sensor of claim 24 wherein said array of electric field sensing electrodes generate finger biometric data based upon a stationary fingerprint placement.

33. The finger biometric sensor of claim 24 further comprising a finger excitation electrode for applying an electric field to the finger;

and wherein said at least one integrated circuit further comprises an excitation drive amplifier adjacent said monocrystalline substrate for driving said finger excitation electrode with an alternating current (AC) signal.

34. A method for making a finger biometric sensor comprising:

forming a thin film transistor (TFT) layer on a thin film substrate, the TFT layer comprising a plurality of TFTs defining a plurality of TFT amplifier stages;

forming an array of electric field sensing electrodes adjacent the TFT layer for receiving a finger adjacent thereto, each electric field sensing electrodes being associated with a respective TFT amplifier stage;

forming a finger excitation electrode for applying an electric field to the finger;

positioning at least one integrated circuit adjacent the thin film substrate, the at least one integrated circuit comprising a monocrystalline substrate processing circuitry adjacent the monocrystalline substrate; and

connecting the processing circuitry to the TFT amplifier stages.

35. The method of claim 34 wherein the TFT layer further comprises a plurality of TFT switching circuits each connected between the output of a respective TFT amplifier stage and the processing circuitry;

and wherein the at least one integrated circuit further comprises an addressing circuit adjacent the monocrystalline substrate for selectively operating the TFT switching circuits.

36. The method of claim 35 wherein the addressing circuit selectively operates the TFT switching elements to provide time domain multiplexing.

37. The method of claim 35 wherein the addressing circuit selectively operates the TFT switching elements to provide frequency domain multiplexing.

38. The method of claim 35 wherein the TFT switching elements are arranged in rows and columns;

and wherein the addressing circuit sequentially operates at least one of rows and columns of the TFT switching circuits.

39. The method of claim 34 wherein each TFT amplifier stage comprises a differential TFT pair;

wherein the at least one integrated circuit further comprises a plurality of gain amplifier stages adjacent the monocrystalline substrate, and further comprising connecting each gain amplifier stage between a respective TFT amplifier stage and the processing circuitry.

40. The method of claim 39 wherein connecting each gain amplifier stage comprises connecting each gain amplifying stage connected in a feedback loop to its respective TFT amplifier stage.

41. The method of claim 34 wherein the at least one integrated circuit further comprises an excitation drive amplifier adjacent the monocrystalline substrate for driving the finger excitation electrode with an alternating current (AC) signal.

42. The method of claim 34 further comprising forming a respective shield electrode for shielding each electric field sensing electrode from adjacent field sensing electrodes.

43. The method of claim 34 wherein the array of electric field sensing electrodes are for generating finger biometric data based upon a sliding finger placement.

44. The method of claim 34 wherein the array of electric field sensing electrodes are for generating finger biometric data based upon a stationary fingerprint placement.