SENSOR ARRAY WITH RECEIVER BIAS ELECTRODE

• US 20150016223A1
• Filed: 07/15/2014
• Published: 01/15/2015
• Est. Priority Date: 07/15/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Dickinson, Timothy, Mathe, Lennart Karl-Axel, McCarthy, Scott, Djordjev, Kostadin Dimitrov, Oliveira, Louis Dominic, Zhou, Qubo
• Granted Patent: US 9,990,089 B2
• Time in Patent Office: Days
• US Class Current: 367/87
• CPC Class Codes: G01H 1/04 of vibrations which are transverse to direction of propagation
• CPC Class Codes: G01S 15/02 using reflection of acoustic waves G01S15/66 takes precedence
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/043 using propagating acoustic waves
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate

Abstract

A method of operation of an ultrasonic sensor array includes receiving a receiver bias voltage at a receiver bias electrode of the ultrasonic sensor array to bias piezoelectric sensor elements of the ultrasonic sensor array. The method further includes receiving a transmitter control signal at the ultrasonic sensor array to cause an ultrasonic transmitter of the ultrasonic sensor array to generate an ultrasonic wave. The method further includes generating data samples based on a reflection of the ultrasonic wave. The receiver bias voltage and the transmitter control signal are received from an integrated circuit that is coupled to the ultrasonic sensor array.

Claims

1. A method of operating an ultrasonic sensor array, the method comprising:

receiving a receiver bias voltage at a receiver bias electrode of the ultrasonic sensor array to bias piezoelectric sensor elements of the ultrasonic sensor array;

receiving a transmitter control signal at the ultrasonic sensor array to cause an ultrasonic transmitter of the ultrasonic sensor array to generate an ultrasonic wave; and

generating data samples based on a reflection of the ultrasonic wave,

wherein the receiver bias voltage and the transmitter control signal are received from an integrated circuit that is coupled to the ultrasonic sensor array,

wherein the receiver bias voltage has a hold value during a first time interval that is prior to a main burst of the ultrasonic wave,

wherein the receiver bias voltage has a block value during a second time interval associated with the main burst of the ultrasonic wave, and

wherein the receiver bias voltage has a sample value during a third time interval associated with a reflection of the ultrasonic wave.

2. The method of claim 1, wherein the receiver bias voltage has the block value during a fourth time interval associated with a bounce of the reflection of the ultrasonic wave.

3. The method of claim 2, wherein the receiver bias voltage transitions from the block value to the hold value during the fourth time interval.

4. The method of claim 1, wherein the transmitter control signal corresponds to a burst signal that is received from a resonant circuit and wherein the ultrasonic wave is generated based on the burst signal.

5. The method of claim 1, wherein the piezoelectric sensor elements include thin-film transistors (TFTs) coupled to a piezoelectric receiver layer of the ultrasonic sensor array, and wherein the piezoelectric receiver layer is coupled to the receiver bias electrode.

6. The method of claim 1, wherein the ultrasonic sensor array is integrated within a mobile device, and wherein the ultrasonic wave is substantially perpendicular to a surface of a display device of the mobile device.

7. The method of claim 1, wherein the ultrasonic wave is reflected from a stylus or a finger of a user, and wherein the block value is greater than the hold value, and wherein the hold value is greater than the sample value.

8. The method of claim 1, wherein the data samples are generated by the piezoelectric sensor elements based on the reflection of the ultrasonic wave, and wherein the data samples are accessed by the integrated circuit.

9. The method of claim 8, wherein the receiver bias voltage is received from a first terminal of the integrated circuit, wherein the data samples are accessed by the integrated circuit via a second terminal of the integrated circuit, and wherein the transmitter control signal is received from a third terminal of the integrated circuit.

10. The method of claim 1, wherein the ultrasonic sensor array includes the ultrasonic transmitter.

11. An apparatus comprising:

piezoelectric sensor elements of an ultrasonic sensor array;

a receiver bias electrode, wherein the receiver bias electrode is configured to receive a receiver bias voltage to bias the piezoelectric sensor elements of the ultrasonic sensor array; and

an ultrasonic transmitter configured to receive a transmitter control signal to cause the ultrasonic transmitter to generate an ultrasonic wave,

wherein the receiver bias voltage and the transmitter control signal are received from an integrated circuit that is coupled to the ultrasonic sensor array,

wherein the ultrasonic sensor array is configured to generate data samples based on a reflection of the ultrasonic wave,

wherein the receiver bias voltage has a hold value during a first time interval that is prior to a main burst of the ultrasonic wave,

wherein the receiver bias voltage has a block value during a second time interval associated with the main burst of the ultrasonic wave, and

wherein the receiver bias voltage has a sample value during a third time interval associated with a reflection of the ultrasonic wave.

12. The apparatus of claim 11, wherein the receiver bias electrode includes a metal layer that is adjacent to a piezoelectric receiver layer, and wherein the piezoelectric receiver layer is coupled to the piezoelectric sensor elements.

13. The apparatus of claim 11, wherein the receiver bias electrode is configured to couple the receiver bias voltage to each of the piezoelectric sensor elements.

14. The apparatus of claim 11, wherein the integrated circuit is an application-specific integrated circuit (ASIC) that is configured to drive the ultrasonic sensor array.

15. The apparatus of claim 14, wherein the ultrasonic sensor array is responsive to a resonant circuit that is controlled by the ASIC, and wherein the resonant circuit includes inductors.

16. The apparatus of claim 14, further comprising one or more multiplexers (MUXs) of the ultrasonic sensor array, wherein the one or more MUXs are configured to provide the data samples to the ASIC.

17. The apparatus of claim 16, wherein the one or more MUXs are further configured to provide the data samples to the ASIC based on a second plurality of enable signals received from a row-read state machine of the ASIC.

18. The apparatus of claim 11, further comprising a display device, wherein the ultrasonic sensor array is integrated within the display device.

19. The apparatus of claim 18, further comprising a mobile device, wherein the mobile device includes the display device.

20. The apparatus of claim 11, further comprising a substrate, wherein the piezoelectric sensor elements are formed on the substrate.

21. The apparatus of claim 11, further comprising a resonant circuit coupled between the ultrasonic transmitter and the integrated circuit, wherein the transmitter control signal corresponds to a burst signal that is received from the integrated circuit via the resonant circuit, and wherein the ultrasonic wave is generated based on the burst signal.

22. The apparatus of claim 11, wherein the piezoelectric sensor elements include a thin film transistor (TFT) pixel circuit that includes a diode that is responsive to a diode bias signal.

23. The apparatus of claim 22, wherein the TFT pixel circuit further includes a first transistor, and wherein the first transistor is responsive to the receiver bias voltage via capacitive coupling.

24. The apparatus of claim 23, wherein a gate terminal of the first transistor is capacitively coupled to the receiver bias electrode via a capacitor.

25. The apparatus of claim 23, wherein the ultrasonic sensor array further includes a piezoelectric receiver layer that is configured to generate a surface charge based on the reflection of the ultrasonic wave, and wherein the TFT pixel circuit is configured to generate a signal based on the surface charge using the diode and the first transistor.

26. The apparatus of claim 23, wherein the TFT pixel circuit further includes a second transistor, wherein the second transistor is responsive to the signal to generate a data output signal of the TFT pixel circuit.

27. An apparatus comprising:

means for biasing piezoelectric sensor elements of an ultrasonic sensor array using a receiver bias voltage;

means for generating an ultrasonic wave based on a transmitter control signal received at the ultrasonic sensor array; and

means for generating data samples based on a reflection of the ultrasonic wave,

wherein the receiver bias voltage and the transmitter control signal are received from an integrated circuit that is coupled to the ultrasonic sensor array,

wherein the receiver bias voltage has a hold value during a first time interval that is prior to a main burst of the ultrasonic wave,

wherein the receiver bias voltage has a block value during a second time interval associated with the main burst of the ultrasonic wave, and

wherein the receiver bias voltage has a sample value during a third time interval associated with a reflection of the ultrasonic wave.

28. The apparatus of claim 27, wherein the means for biasing the piezoelectric sensor elements includes a receiver bias electrode, wherein the means for generating the ultrasonic wave includes an ultrasonic transmitter, and wherein the means for generating the data samples includes piezoelectric sensor elements.