Method and apparatus for isolating ultrasonic touch sensor from reflections in a device housing

Patent metadata

Field	Value
Publication number	US-10877606-B2
Application number	US-201916390911-A
Country	US
Kind code	B2
Filing date	Apr 22, 2019
Priority date	Apr 22, 2019
Publication date	Dec 29, 2020
Grant date	Dec 29, 2020

Abstract

Acoustic touch sensing system architectures and methods for acoustic touch sensing can be used to detect a position of an object touching a surface. Acoustic touch sensing can utilize transducers (e.g., piezoelectric) to simultaneously transmit ultrasonic waves along a surface and through a thickness of a material. The location of the object can be determined based on the amount of time elapsing between the transmission of the waves and receipt of the reflected waves. In some examples, an acoustic touch sensing system can be insensitive to water contact on the device surface, and thus acoustic touch sensing can be used for touch sensing in devices that may become wet or fully submerged in water. In some examples, techniques such as isolation and absorption of acoustic energy can be used to mitigate acoustic energy reflected by portions of the electronic device and interfere with the acoustic touch sensing operation.

First claim

What is claimed is:

1. An electronic device, comprising:
a front cover material;
a transducer assembly coupled to an edge portion of the front cover material by a first adhesive layer;
a second adhesive layer coupled between the transducer assembly and a first surface of a housing of the electronic device, wherein the second adhesive layer provides a seal around a perimeter of the front cover material and provides an acoustic isolation between the transducer assembly and the housing based on an impedance mismatch between the second adhesive layer and the housing; and
an absorption layer disposed on a second surface of the housing, different from the first surface of the housing, wherein the absorption layer is disposed intersecting a wave propagation direction of an acoustic wave produced by the transducer assembly.

2. The electronic device of claim 1 , wherein the second adhesive layer is a foam pressure sensitive adhesive.

3. The electronic device of claim 1 , wherein the first adhesive layer has a first shear modulus, and the second adhesive layer has a second shear modulus, wherein a ratio between the first shear modulus and the second shear modulus is at least about 100:1.

4. The electronic device of claim 1 , wherein the transducer assembly has a third shear modulus and the second adhesive layer has a second shear modulus, wherein a ratio between the third shear modulus and the second shear modulus is at least about 250:1.

5. The electronic device of claim 1 , wherein the transducer assembly has a third shear modulus and the second adhesive layer has a second shear modulus, wherein a ratio between the third shear modulus and the second shear modulus is at least about 1000:1.

6. The electronic device of claim 1 , wherein the housing has a fourth shear modulus and the second adhesive layer has a second shear modulus, wherein a ratio between the fourth shear modulus and the second shear modulus is at least about 250:1.

7. The electronic device of claim 1 , wherein the transducer housing has a fourth shear modulus and the second adhesive layer has a second shear modulus, wherein a ratio between the fourth shear modulus and the second shear modulus is at least about 120.

8. The electronic device of claim 1 , wherein the second adhesive layer has a shear modulus of at most about 0.02 gigapascals.

9. An electronic device, comprising:
a front cover material;
a transducer assembly coupled to an edge portion of the front cover material by a first adhesive layer;
a second adhesive layer coupled between the transducer assembly and a first surface of a housing of the electronic device; and
an absorption layer disposed upon a second, inner surface of the housing, wherein the absorption layer is disposed intersecting a wave propagation direction of an acoustic wave produced by the transducer assembly.

10. The electronic device of claim 9 , wherein the absorption layer comprises a soft epoxy and particles of a high shear modulus material.

11. The electronic device of claim 10 , wherein the high shear modulus material comprises tungsten.

12. An electronic device, comprising:
a front cover material;
a transducer assembly coupled to an edge portion of the front cover material by a first adhesive layer;
an acoustic isolation means for providing isolation between the transducer assembly and a first surface of a housing of the electronic device, wherein the acoustic isolation means provides a seal around a perimeter of the front cover material and the acoustic isolation is based on an impedance mismatch between the acoustic isolation means and the housing; and
an acoustic absorption means for intersecting a wave propagation direction of an acoustic wave produced by the transducer assembly at a second surface of the housing, different from the first surface of the housing.

13. The electronic device of claim 12 , wherein the acoustic isolation means is a foam pressure sensitive adhesive.

14. The electronic device of claim 12 , wherein the first adhesive layer has a first shear modulus, and the acoustic isolation means has a second shear modulus, wherein a ratio between the first shear modulus and the second shear modulus is at least about 100:1.

15. The electronic device of claim 12 , wherein the transducer assembly has a third shear modulus and the acoustic isolation means has a second shear modulus, wherein a ratio between the third shear modulus and the second shear modulus is at least about 250:1.

16. The electronic device of claim 12 , wherein the transducer assembly has a third shear modulus and the acoustic isolation means has a second shear modulus, wherein a ratio between the third shear modulus and the second shear modulus is at least about 1000:1.

17. The electronic device of claim 12 , wherein the housing has a fourth shear modulus and the acoustic isolation means has a second shear modulus, wherein a ratio between the fourth shear modulus and the second shear modulus is at least about 250:1.

18. The electronic device of claim 12 , wherein the transducer housing has a fourth shear modulus and the acoustic isolation means has a second shear modulus, wherein a ratio between the fourth shear modulus and the second shear modulus is at least about 120:1.

19. The electronic device of claim 12 , wherein the acoustic isolation means has a shear modulus of at most about 0.02 gigapascals.

20. The electronic device of claim 1 , wherein the housing has a fourth shear modulus and the second adhesive layer has a second shear modulus, wherein a ratio between the fourth shear modulus and the second shear modulus is at least about 200:1.

Assignees

• Apple Inc

Inventors

• Khajeh Ehsan
• Al-Okaily Ala'A
• King Brian Michael
• Mak George Ho Yin
• Datta Supratik

Classifications

• G06F3/043

  using propagating acoustic waves · CPC title

• G06F3/0436 Primary

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