Micromechanical ultrasonic transducers and display
An apparatus may include a one- or two-dimensional array of micromechanical ultrasonic transducer (PMUT) elements positioned below, beside, with, on, or above a backplane of a visual display. The backplane may be a thin-film transistor (TFT) backplane. The array of PMUT elements may be a piezoelectric micromechanical ultrasonic transducer (PMUT) array or a capacitive micromechanical ultrasonic transducer (CMUT) array. The PMUT array may be configurable to operate in modes corresponding to multiple frequency ranges. When operating in the low-frequency mode, the apparatus may be capable of gesture detection. A high-frequency mode may include a fingerprint sensor mode or a stylus detection mode.
1. A display device, comprising:
a substrate;
a display coupled to the substrate;
a piezoelectric micromechanical ultrasonic transducer (PMUT) array proximate the display, wherein at least a portion of the PMUT array resides on the substrate;
a plurality of thin-film transistors (TFTs), at least a first array of the TFTs residing on the substrate and including circuitry for controlling the display and at least a second array of the TFTs residing on the substrate and including circuitry for controlling at least a portion of the PMUT array; and
a control system.
2. The display device of claim 1 , wherein the control system is capable of:
making a determination whether to operate at least a portion of the PMUT array in at least one of a low-frequency mode or a high-frequency mode; and
controlling at least a portion of the PMUT array to operate in at least one of the low-frequency mode or the high-frequency mode, according to the determination.
3. The display device of claim 2 , further including an interface system, wherein the determination is made, at least in part, according to input received from the interface system.
4. The display device of claim 2 , wherein the low-frequency mode corresponds to a frequency range of approximately 50 kHz to 200 kHz.
5. The display device of claim 2 , wherein the low-frequency mode corresponds to a gesture detection mode, wherein free-space gestures near the display may be detected.
6. The display device of claim 2 , wherein the high-frequency mode corresponds to a frequency range of approximately 1 MHz to 25 MHz.
7. The display device of claim 2 , wherein the high-frequency mode corresponds to a fingerprint sensor mode or a stylus detection mode.
8. The display device of claim 7 , wherein the control system is capable of performing an authentication process based, at least in part, on fingerprint data acquired while the PMUT array operates in the fingerprint sensor mode.
9. The display device of claim 8 , further including a memory system, wherein the authentication process involves:
providing a prompt, via the display, to place at least one finger on a surface of the display device;
receiving, via at least a portion of the PMUT array, at least one fingerprint image;
determining received fingerprint data corresponding to the at least one fingerprint image; and
comparing the received fingerprint data with stored fingerprint data in the memory system.
10. The display device of claim 2 , wherein the control system is capable of:
making a determination whether to operate at least a portion of the PMUT array in the high-frequency mode, the low-frequency mode or a medium-frequency mode; and
controlling at least a portion of the PMUT array to operate in the high-frequency mode, the low-frequency mode or the medium-frequency mode, according to the determination.
11. The display device of claim 10 , wherein the display device is capable of providing touch sensor functionality when the control system is controlling at least a portion of the PMUT array to operate in the medium-frequency mode.
12. The display device of claim 10 , wherein the medium-frequency mode corresponds to a frequency range of approximately 200 kHz to 1 MHz.
13. The display device of claim 2 , wherein the control system is capable of controlling first PMUT elements of the PMUT array to operate in the low-frequency mode and second PMUT elements of the PMUT array to operate in the high-frequency mode.
14. The display device of claim 2 , wherein the control system is capable of controlling a PMUT element of the PMUT array to operate in the low-frequency mode and to operate in the high-frequency mode.
15. The display device of claim 1 , wherein the PMUT array is a piezoelectric micromechanical ultrasonic transducer (pMUT) array or a capacitive micromechanical ultrasonic transducer (cMUT) array.
16. The display device of claim 1 , wherein the control system is capable of addressing at least a portion of the PMUT array for at least one of wavefront beam forming, beam steering, receive-side beam forming, or selective readout of returned signals.
17. The display device of claim 16 , wherein the control system is capable of addressing at least a portion of the PMUT array to produce wavefronts of a substantially planar, spherical or cylindrical shape.
18. The display device of claim 16 , wherein the control system is capable of addressing at least a portion of the PMUT array to produce constructive or destructive interference in at least one location.
19. The display device of claim 1 , wherein the control system is capable of exciting PMUT elements of the PMUT array and detecting responses via the same PMUT elements.
20. The display device of claim 1 , wherein the control system is capable of controlling a first PMUT element of the PMUT array as an acoustic transmitter and a second PMUT element of the PMUT array as an acoustic receiver.
21. The display device of claim 1 , wherein at least a portion of the PMUT array is an active matrix PMUT array.
22. The display device of claim 21 , wherein the active matrix PMUT array includes drive circuitry and sense circuitry.
23. The display device of claim 21 , wherein the active matrix PMUT array includes at least one of row and column addressing circuitry, multiplexer circuitry, demultiplexer circuitry, local amplification circuitry or analog-to-digital conversion circuitry.
24. The display device of claim 1 , wherein at least a portion of the PMUT array is disposed behind only a part of the display.
25. The display device of claim 1 , wherein at least a portion of the PMUT array is disposed in a peripheral area of the display.
26. The display device of claim 1 , wherein the control system is capable of controlling a portion of the PMUT array that is disposed in the peripheral area of the display for at least one of fingerprint sensor functionality, signature pad functionality, stylus detection functionality, gesture detection functionality or button functionality.
27. The display device of claim 1 , wherein at least a portion of the PMUT array is disposed behind substantially all of the display.
28. The display device of claim 1 , wherein the substrate is a glass substrate.
29. The display device of claim 1 , wherein the circuitry for controlling at least a portion of the PMUT array and the circuitry for controlling the display are capable of sharing a flex cable.
30. The display device of claim 1 , further comprising:
a cover glass;
electrodes disposed on the cover glass, the electrodes configured for topside electrical connections to circuitry for controlling at least a portion of the PMUT array.
31. The display device of claim 30 , wherein the electrodes are configured for connections with circuitry for at least one PMUT element that is disposed on a periphery of the display.
32. The display device of claim 1 , wherein a single PMUT element of the PMUT array corresponds with a single pixel of the display.