ULTRASONIC SENSOR WITH BONDED PIEZOELECTRIC LAYER

• US 20140352440A1
• Filed: 06/02/2014
• Published: 12/04/2014
• Est. Priority Date: 06/03/2013
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Buchan, Nicholas Ian, Burns, David William, Djordjev, Kostadin Dimitrov, Kitchens, Jack Conway II, Fennell, Leonard Eugene, Gojevic, Stephen Michael, Schneider, John Keith, Bennett, Nathaniel Robert, Lavery, Kristopher Andrew
• Granted Patent: US 10,036,734 B2
• Time in Patent Office: Days
• US Class Current: 73/632
• CPC Class Codes: G01N 29/22 Details , e.g. general constructional or apparatus details
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: H10N 30/03 Assembling devices that include piezoelectric or electrostrictive parts
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

This disclosure provides systems, methods and apparatus related to an ultrasonic sensor for detecting ultrasonic energy. In some implementations, the ultrasonic sensor includes a piezoelectric receiver layer bonded with an adhesive to an array of pixel circuits disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit. Methods of forming ultrasonic sensors include bonding piezoelectric receiver layers to TFT arrays.

Claims

1. An apparatus comprising:

an ultrasonic transmitter for generating ultrasonic energy;

a platen; and

an ultrasonic receiver for detecting ultrasonic energy including;

an array of thin film transistor (TFT) pixel circuits disposed on a TFT substrate;

a piezoelectric receiver layer having first and second opposing surfaces, the first surface bonded with an adhesive to the TFT substrate; and

a receiver bias electrode overlying the second surface of the piezoelectric receiver layer, wherein the piezoelectric receiver layer is in electrical communication with the TFT pixel circuits.

2. The apparatus of claim 1, further comprising a spacer layer bonded between the platen and the ultrasonic receiver.

3. The apparatus of claim 1, wherein the piezoelectric receiver layer is disposed between the platen and the TFT substrate and the ultrasonic transmitter is on the opposite side of the TFT substrate as the piezoelectric receiver layer.

4. The apparatus of claim 1, wherein the piezoelectric receiver layer is disposed between the platen and the TFT substrate and the ultrasonic transmitter is on the same side of the TFT substrate as the piezoelectric receiver layer.

5. The apparatus of claim 1, wherein the TFT substrate is disposed between the platen and the piezoelectric receiver layer and the ultrasonic transmitter is on the opposite side of the TFT substrate as the piezoelectric receiver layer.

6. The apparatus of claim 1, wherein the TFT substrate is disposed between the platen and the piezoelectric receiver layer and the ultrasonic transmitter is on the same side of the TFT substrate as the piezoelectric receiver layer.

7. The apparatus of claim 1, further comprising a protective cap on the opposite side of the TFT substrate as the platen and bonded to the TFT substrate.

8. The apparatus of claim 1, further comprising a flexible printed circuit bonded to the TFT substrate.

9. The apparatus of claim 1, wherein the receiver bias electrode is disposed on a flexible printed circuit.

10. The apparatus of claim 1, wherein the ultrasonic transmitter includes a piezoelectric transmitter layer having first and second opposing surfaces, a first transmitter electrode overlying the first surface and a second transmitter electrode overlying the second surface.

11. The apparatus of claim 10, wherein the one of the first and second transmitter electrodes is disposed on a flexible printed circuit.

12. An apparatus comprising:

an ultrasonic receiver for detecting ultrasonic energy including;

an array of thin film transistor (TFT) pixel circuits disposed on a TFT substrate;

a piezoelectric layer having first and second opposing surfaces, the first surface bonded with an adhesive to the TFT substrate; and

a receiver bias electrode overlying the second surface of the piezoelectric layer;

wherein the piezoelectric layer is in electrical communication with the TFT pixel circuits.

13. The apparatus of claim 12, wherein the adhesive has a lateral resistivity of at least 1 MΩ

-cm.

14. The apparatus of claim 12, wherein the adhesive is selected from an anisotropic conductive film (ACF) and (3-Aminopropyl)triethoxysilane (APTES).

15. The apparatus of claim 12, wherein the adhesive has a thickness of no more than about 10 μ

m.

16. The apparatus of claim 12, further comprising a flexible printed circuit (FPC) overlying the second surface of the piezoelectric layer, wherein the FPC includes the receiver bias electrode.

17. The apparatus of claim 16, wherein the FPC is bonded to one or more conductive pads on the TFT substrate.

18. An apparatus comprising:

an array of thin film transistor (TFT) pixel circuits disposed on a TFT substrate;

an ultrasonic transmitter for generating ultrasonic energy including a piezoelectric transmitter layer;

an ultrasonic receiver for detecting ultrasonic energy including a piezoelectric receiver layer having first and second opposing surfaces, the first surface bonded with an adhesive to the TFT substrate; and

a piezoelectric layer wrapped around the TFT substrate, wherein the piezoelectric layer forms the piezoelectric transmitter layer and the piezoelectric receiver layer.

19. The apparatus of claim 18, further comprising a platen and wherein the piezoelectric receiver layer is disposed between the TFT substrate and the platen.

20. The apparatus of claim 18, further comprising a platen and wherein the piezoelectric transmitter layer is disposed between the TFT substrate and the platen.

21. A method comprising:

providing a thin film transistor (TFT) substrate;

providing a piezoelectric receiver;

providing a piezoelectric transmitter;

providing a flexible printed circuit (FPC); and

assembling the TFT substrate, piezoelectric receiver, piezoelectric transmitter, and the FPC to form an ultrasonic sensor.

22. The method of claim 21, further comprising providing a spacer layer and assembling the spacer layer with the TFT substrate, the piezoelectric receiver, the piezoelectric transmitter, and the FPC to form the ultrasonic sensor.

23. The method of claim 21, further comprising providing a backside cap and assembling the backside cap with the TFT substrate, the piezoelectric receiver, the piezoelectric transmitter, and the FPC to form the ultrasonic sensor.

24. The method of claim 21, wherein assembling the TFT substrate, the piezoelectric receiver, the piezoelectric transmitter, and the FPC includes:

bonding the piezoelectric receiver to the TFT substrate;

bonding the FPC to the TFT substrate;

electrically connecting a receiver bias electrode of the piezoelectric receiver;

bonding the piezoelectric transmitter; and

electrically connecting transmitter electrodes of the piezoelectric transmitter.

25. The method of claim 24, further comprising bonding a spacer layer to the piezoelectric receiver.

26. The method of claim 24, further comprising bonding a backside cap.