Shear-poled curved piezoelectric material

Patent metadata

Field	Value
Publication number	US-10949030-B2
Application number	US-201816123757-A
Country	US
Kind code	B2
Filing date	Sep 6, 2018
Priority date	Sep 26, 2017
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

Acoustic transducers can be formed form piezoelectric materials including one or more curved (non-linear) segments. The piezoelectric material can be shear poled such that a poling direction of the piezoelectric material can follow the curvature of the piezoelectric material. The piezoelectric material can also have a unidirectional poling direction. In some examples, the piezoelectric material can be a closed ring with a circular or partially circular shape. A shear poling process for a piezoelectric material with curves can include shear poling segments of the piezoelectric material with one or more sets of poling electrodes. The poling electrodes of a respective one of the one or more sets of poling electrodes can be coupled to the same side of the piezoelectric material.

First claim

What is claimed is:

1. A piezoelectric material comprising:
a curved segment, the curved segment coupled to a plurality of electrodes;
wherein a direction of shear poling by the plurality of electrodes in the curved segment follows a single shear poling direction along a curvature of the curved segment when an opposite voltage is applied to each of a pair of electrodes in the plurality of electrodes, the electrodes in the pair being on a same curved side of the piezoelectric material.

2. The piezoelectric material of claim 1 , wherein the piezoelectric material, when excited, generates a threshold percentage of total energy in a selected shear mode.

3. The piezoelectric material of claim 1 , wherein the direction of shear poling is within a threshold amount of a line tangential to the curvature of the curved segment.

4. The piezoelectric material of claim 1 , wherein the piezoelectric material comprises a closed ring shape.

5. The piezoelectric material of claim 1 , wherein the piezoelectric material comprises a circular or a partially circular shape.

6. The piezoelectric material of claim 1 , wherein the piezoelectric material comprises a plurality of elbow shaped segments.

7. The piezoelectric material of claim 1 , wherein the piezoelectric material comprises a first curved segment, a second curved segment and a linear segment, wherein the first curved segment and the second curved segment are connected by the linear segment, the linear segment having a length greater than a length of the first curved segment or a length of the second curved segment.

8. The piezoelectric material of claim 1 , wherein the plurality of electrodes are configured to have a relative position between the plurality of electrodes and the piezoelectric material adjusted by moving the curved piezoelectric material or by moving the plurality of electrodes.

9. An acoustic touch-sensitive device comprising:
a cover glass; and
one or more piezoelectric transducers coupled to the cover glass, wherein the one or more piezoelectric transducers are shear-poled to generate shear acoustic waves in the cover glass;
wherein at least one of the one or more piezoelectric transducers comprises a curved segment and a direction of shear poling in the curved segment follows a single direction of shear poling along a curvature of the curved segment when opposite voltages are applied to each of a pair of electrodes coupled to the curved segment, the electrodes in the pair being on a same curved side of the transducer.

10. The acoustic touch-sensitive device of claim 9 , wherein the one or more piezoelectric transducers comprises a ring-shaped piezoelectric material.

11. The acoustic touch-sensitive device of claim 10 , wherein a circumference of the ring-shaped piezoelectric material is within a threshold of a circumference of the cover glass.

12. The acoustic touch-sensitive device of claim 9 , wherein the one or more piezoelectric transducers comprises four curved piezoelectric transducers disposed at four corners of the cover glass and four linear piezoelectric transducers disposed along edges of the cover glass between the curved piezoelectric transducers.

13. The acoustic touch-sensitive device of claim 9 , wherein the plurality of electrodes are configured to have a relative position between the plurality of electrodes and the piezoelectric material adjusted by moving the curved piezoelectric material or by moving the plurality of electrodes.

14. A method of shear poling a curved piezoelectric material, the method comprising:
shear poling a plurality of segments of the curved piezoelectric material in a single direction along a curvature of a curved segments including poling one or more first segments of the plurality of segments of the curved piezoelectric material during a first time period including applying an opposite voltage to each of a first pair of electrodes coupled to a same curved side of the piezoelectric material and shear poling one or more second segments of the plurality of segments of the curved piezoelectric during a second time period including applying the opposite voltages to each of a second pair of electrodes coupled to a same curved side of the piezoelectric material.

15. The method of claim 14 , wherein poling the one or more first segments comprises applying a first voltage across two respective electrodes disposed on a first surface of the curved piezoelectric material on opposite ends of a respective first segment.

16. The method of claim 15 , wherein poling the one or more first segments comprises applying a second voltage across two respective electrodes disposed on a second surface of the curved piezoelectric material on opposite ends of the respective first segment.

17. The method of claim 14 , further comprising:
coupling a first plurality of poling electrodes to a first surface of the curved piezoelectric material.

18. The method of claim 17 , further comprising:
coupling a second plurality of poling electrodes to a second surface of the curved piezoelectric material, the first surface and the second surface on opposite sides of the curved piezoelectric material.

19. The method of claim 17 , further comprising:
activating a first subset of the first plurality of poling electrodes by coupling the first subset of the first plurality of poling electrodes to a voltage source;
deactivating a second subset of the first plurality of poling electrodes by decoupling the second subset of the first plurality of poling electrodes from the voltage source.

20. The method of claim 17 , further comprising:
adjusting a relative position between the first plurality of poling electrodes and the curved piezoelectric material by moving the curved piezoelectric material or by moving the first plurality of poling electrodes.

21. The method of claim 17 , wherein the first plurality of poling electrodes have a first spacing for linear segments of the curved piezoelectric material and a second spacing for curved segments of the curved piezoelectric material.

Assignees

• Apple Inc

Inventors

• Khajeh Ehsan
• Tucker Aaron Scott
• King Brian Michael
• Yip Marcus

Classifications

• G06F3/0436 Primary

  in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate · CPC title

• G06F3/04166

  Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving (Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184) · CPC title

• G06F1/3262

  Power saving in digitizer or tablet · CPC title

• Y02D10/00

  Energy efficient computing, e.g. low power processors, power management or thermal management · CPC title

• G06F2203/04104

  Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger · CPC title