Apparatus with ultrasonic fingerprint sensor and one or more resonators, and related systems and methods

Patent metadata

Field	Value
Publication number	US-12333846-B2
Application number	US-202318513144-A
Country	US
Kind code	B2
Filing date	Nov 17, 2023
Priority date	Sep 17, 2021
Publication date	Jun 17, 2025
Grant date	Jun 17, 2025

Abstract

Some disclosed implementations include an ultrasonic sensor stack and an acoustic resonator. The acoustic resonator may be configured to enhance ultrasonic waves transmitted by the ultrasonic sensor stack in an ultrasonic frequency range that is suitable for ultrasonic fingerprint sensors. In some examples, the acoustic resonator may include one or more low-impedance layers residing between a first higher-impedance layer and a second higher-impedance layer. Each of the one or more low-impedance layers may have a lower acoustic impedance than an acoustic impedance of the first higher-impedance layer or an acoustic impedance of the second higher-impedance layer. At least one low-impedance layer may have a thickness corresponding to a multiple of a half wavelength at a peak frequency of the acoustic resonator. The peak frequency may be within a frequency range from 1 MHz. to 20 MHz.

First claim

The invention claimed is:

1. An apparatus, comprising:
an ultrasonic sensor stack; and
an acoustic resonator, comprising:
a first higher-impedance layer;
a second higher-impedance layer; and
one or more low-impedance layers residing between the first higher-impedance layer and the second higher-impedance layer, each of the one or more low-impedance layers having a lower acoustic impedance than an acoustic impedance of the first higher-impedance layer or an acoustic impedance of the second higher-impedance layer, at least one of the one or more low-impedance layers having a thickness corresponding to a multiple of a quarter wavelength at a peak frequency of the acoustic resonator.

2. The apparatus of claim 1 , wherein at least one of the first higher-impedance layer or the second higher-impedance layer has a thickness corresponding to a multiple of a quarter wavelength at the peak frequency of the acoustic resonator.

3. The apparatus of claim 1 , wherein at least one of the first higher-impedance layer or the second higher-impedance layer has a thickness corresponding to less than one-eighth of a wavelength at the peak frequency of the acoustic resonator.

4. The apparatus of claim 1 , wherein the ultrasonic sensor stack resides adjacent to the second higher-impedance layer.

5. The apparatus of claim 1 , wherein the one or more low-impedance layers comprise:
a first low-impedance layer having a thickness corresponding to a multiple of a quarter wavelength at the peak frequency of the acoustic resonator; and
a second low-impedance layer residing adjacent to the second higher-impedance layer, the second low-impedance layer having a thickness corresponding to a multiple of a half wavelength at the peak frequency of the acoustic resonator.

6. The apparatus of claim 5 , wherein the one or more low-impedance layers further comprise:
a third low-impedance layer residing between the first low-impedance layer and the first higher-impedance layer;
a fourth low-impedance layer residing between the first low-impedance layer and the third low-impedance layer;
a fifth low-impedance layer residing between the second low-impedance layer and the second higher-impedance layer;
a sixth low-impedance layer residing between the fifth low-impedance layer and the second higher-impedance layer; and
a seventh low-impedance layer residing between the sixth low-impedance layer and the second higher-impedance layer, wherein the third low-impedance layer, the fourth low-impedance layer, the fifth low-impedance layer, the sixth low-impedance layer and the seventh low-impedance layer each have a thickness corresponding to a multiple of the quarter wavelength at the peak frequency.

7. The apparatus of claim 6 , wherein the first low-impedance layer, the third low-impedance layer, the fifth low-impedance layer and the seventh low-impedance layer each have a lower acoustic impedance than the acoustic impedance of the second low-impedance layer, the fourth low-impedance layer or the sixth low-impedance layer.

8. The apparatus of claim 1 , wherein at least one of the first higher-impedance layer or the second higher-impedance layer comprises glass.

9. The apparatus of claim 1 , wherein at least one of the first higher-impedance layer or the second higher-impedance layer comprises metal.

10. The apparatus of claim 1 , wherein at least one of the first higher-impedance layer or the second higher-impedance layer comprises a plurality of layers having a thickness corresponding to a multiple of a quarter wavelength at the peak frequency of the acoustic resonator.

11. The apparatus of claim 10 , wherein the plurality of layers includes at least a first layer and a second layer, the first layer having a first acoustic impedance that is higher than a second acoustic impedance of the second layer.

12. The apparatus of claim 1 , further comprising a display stack.

13. The apparatus of claim 1 , wherein the apparatus is a mobile device that includes the ultrasonic sensor stack and the acoustic resonator.

14. An apparatus, comprising:
ultrasonic sensor means; and
an acoustic resonator, comprising:
a first higher-impedance layer;
a second higher-impedance layer; and
one or more low-impedance layers residing between the first higher-impedance layer and the second higher-impedance layer, each of the one or more low-impedance layers having a lower acoustic impedance than an acoustic impedance of the first higher-impedance layer or an acoustic impedance of the second higher-impedance layer, at least one of the one or more low-impedance layers having a thickness corresponding to a multiple of a quarter wavelength at a peak frequency of the acoustic resonator.

15. The apparatus of claim 14 , wherein at least one of the first higher-impedance layer or the second higher-impedance layer has a thickness corresponding to a multiple of a quarter wavelength at the peak frequency of the acoustic resonator.

16. The apparatus of claim 14 , wherein at least one of the first higher-impedance layer or the second higher-impedance layer has a thickness corresponding to less than one-eighth of a wavelength at the peak frequency of the acoustic resonator.

17. The apparatus of claim 14 , wherein the ultrasonic sensor means resides adjacent to the second higher-impedance layer.

18. The apparatus of claim 17 , wherein the one or more low-impedance layers comprise:
a first low-impedance layer having a thickness corresponding to a multiple of a quarter wavelength at the peak frequency of the acoustic resonator; and
a second low-impedance layer residing adjacent to the second higher-impedance layer, the second low-impedance layer having a thickness corresponding to a multiple of a half wavelength at the peak frequency.

19. The apparatus of claim 18 , wherein the one or more low-impedance layers further comprise:
a third low-impedance layer residing between the first low-impedance layer and the first higher-impedance layer;
a fourth low-impedance layer residing between the first low-impedance layer and the third low-impedance layer;
a fifth low-impedance layer residing between the second low-impedance layer and the second higher-impedance layer;
a sixth low-impedance layer residing between the fifth low-impedance layer and the second higher-impedance layer; and
a seventh low-impedance layer residing between the sixth low-impedance layer and the second higher-impedance layer, wherein the third low-impedance layer, the fourth low-impedance layer, the fifth low-impedance layer, the sixth low-impedance layer and the seventh low-impedance layer each have a thickness corresponding to a multiple of the quarter wavelength at the peak frequency.

20. The apparatus of claim 19 , wherein the first low-impedance layer, the third low-impedance layer, the fifth low-impedance layer and the seventh low-impedance layer each have a lower acoustic impedance than the acoustic impedance of the second low-impedance layer, the fourth low-impedance layer or the sixth low-impedance layer.

Assignees

• Qualcomm Inc

Inventors

• Strohmann Jessica Liu
• Panchawagh Hrishikesh Vijaykumar
• Kuo Nai-Kuei
• Lu Yipeng
• Lopez Ali
• Djordjev Kostadin Dimitrov

Classifications

• G06F21/32

  using biometric data, e.g. fingerprints, iris scans or voiceprints · CPC title

• H03H9/17

  having a single resonator (crystal tuning forks H03H9/21) · CPC title

• G06V40/1365

  Matching; Classification · CPC title

• G06V40/1306 Primary

  non-optical, e.g. ultrasonic or capacitive sensing · CPC title

• G06F21/75

  by inhibiting the analysis of circuitry or operation · CPC title