Fully-addressable sensor array for acoustic imaging systems

• US 10,133,904 B2
• Filed: 08/10/2015
• Issued: 11/20/2018
• Est. Priority Date: 09/30/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Yazdandoost, Mohammad Yeke, Bussat, Jean-Marie
• Primary Examiner(s): Joseph, Dennis
• Application Number:
  US14/822,614
• Publication Number:
  US 20160092714A1
• Time in Patent Office: 1,198 Days
• CPC Class Codes: G06F 1/1626 with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
• CPC Class Codes: G06F 1/1684 Constructional details or arrangements related to integrated I/O peripherals not covered by groups G06F1/1635 - G06F1/1675
• CPC Class Codes: G06F 21/00 Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
• CPC Class Codes: G06F 21/32 using biometric data, e.g. fingerprints, iris scans or voiceprints
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: Y04S 40/20 Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Abstract

An acoustic imaging system can contain a plurality of individual acoustic elements that each contain an acoustic transducer, drive circuitry, and low voltage sense and/or read circuitry. In many embodiments both the drive circuitry and the read circuitry can be independently addressable. For example, if the individual acoustic elements are arranged into rows and columns, each acoustic element can include row/column drive circuit enable switches and row/column read circuit enable switches.

Claims

1. A fingerprint imaging system comprising:

a high voltage source;

a low-voltage sense circuit; and

an array of acoustic elements, each acoustic element comprising;

a piezoelectric transducer comprising;

a drive/sense lead; and

a ground lead coupled to a circuit ground;

a pair of row/column drive selection switches coupled in series and configured to couple the drive/sense lead of the piezoelectric transducer to the high-voltage source when the acoustic element is operated in a high-voltage drive mode; and

a pair row/column sense selection switches coupled in series and configured to;

couple the drive/sense lead of the piezoelectric transducer to the low-voltage sense circuit when the acoustic element is operated in a low-voltage sense mode; and

decouple the drive/sense lead of the piezoelectric transducer from the low-voltage sense circuit when the acoustic element is operated in the high-voltage drive mode.

2. The fingerprint imaging system of claim 1, wherein each acoustic element of the array of acoustic elements are coupled to a bottom surface of a substrate.

3. The fingerprint imaging system of claim 2, wherein the substrate is formed with one of the group consisting of glass, sapphire, and metal.

4. The fingerprint imaging system of claim 1, wherein each piezoelectric transducer of each acoustic element is formed from a material configured to expand and contract in response to the high-voltage signal.

5. The fingerprint imaging system of claim 1, wherein the high voltage source is configured to output a signal with a direct current bias of approximately 100 volts.

6. The fingerprint imaging system of claim 5, wherein the low-voltage sense circuit is coupled to a low voltage source configured output less than 10 volts.

7. The fingerprint imaging system of claim 1, wherein the high voltage source comprises a common electrode coupled to each acoustic element of the array of acoustic elements.

8. The fingerprint imaging system of claim 1, wherein the voltage sense circuit comprises a common electrode coupled to each piezoelectric transducer of each acoustic element of the array of acoustic elements.

9. The fingerprint imaging system of claim 8, wherein the common electrode comprises a conductive plate.

10. A method of driving an acoustic element of a fingerprint imaging sensor comprising an addressable drive circuit, the method comprising:

opening each of a row sense select switch and column sense select switch that are coupled in series to disconnect a drive lead of the acoustic element from a low-voltage sense circuit;

closing each of a row drive select switch and column drive select switch in series to connect the drive lead the acoustic element to a high-voltage source through the addressable drive circuit; and

driving the acoustic element with a high-voltage signal generated by the high-voltage source;

wherein;

a ground lead of the acoustic element is coupled to a circuit ground.

11. The method of claim 10, wherein the acoustic element comprises an piezoelectric transducer formed from a material configured to expand and contract in response to the high-voltage signal.

12. The method of claim 10, wherein the high-voltage source is configured to output approximately 100 volts.

13. The method of claim 12, wherein the low-voltage sense circuit is coupled to a low voltage source configured to output approximately 3.3 volts.

14. The method of claim 10, wherein the acoustic element is coupled to a bottom surface of a substrate.

15. The method of claim 14, wherein the substrate is formed with one of the group consisting of glass, sapphire, and metal.

16. A method of reading an acoustic element of a fingerprint imaging sensor comprising an addressable read circuit and an addressable drive circuit, the method comprising:

opening each of a row sense select switch and column sense select switch that are coupled in series to disconnect a sense/drive lead of the acoustic element from a low-voltage sense circuit;

closing each of a row drive select switch and column drive select switch that are coupled in series to connect the sense/drive lead of the acoustic element to a high-voltage source through the addressable drive circuit;

opening each of the row drive select switch and column drive select switch to decouple the acoustic element from the high-voltage source;

enabling each of the row sense select switch and column sense select switch to couple the acoustic element to the addressable read circuit; and

obtaining an electrical signal from the acoustic element with the addressable read circuit;

wherein;

a ground lead of the acoustic element is coupled to a circuit ground.

17. The method of claim 16, wherein the acoustic element comprises an piezoelectric transducer formed from a material configured to generate an electrical signal in response to mechanical pressure.

18. The method of claim 16, wherein the high-voltage drive circuit is configured to output a voltage signal having a direct current bias of approximately 100 volts.

19. The method of claim 16, wherein the low-voltage sense circuit is coupled to a low voltage source configured to output approximately 3.3 volts.