OPERATION OF AN ULTRASONIC SENSOR

• US 20170328870A1
• Filed: 05/08/2017
• Published: 11/16/2017
• Est. Priority Date: 05/10/2016
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: GARLEPP, Bruno W., PERROTT, Michael H., SALVIA, James Christian
• Granted Patent: US 10,539,539 B2
• Time in Patent Office: Days
• CPC Class Codes: B06B 1/0629 Square array
• CPC Class Codes: G01N 2291/106 one or more transducer arrays
• CPC Class Codes: G01N 29/34 Generating the ultrasonic, sonic or infrasonic waves , e.g. electronic circuits specially adapted therefor
• CPC Class Codes: G10K 11/346 using phase variation
• CPC Class Codes: G11C 19/287 Organisation of a multiplicity of shift registers
• CPC Class Codes: G11C 19/38 two-dimensional, e.g. horizontal and vertical shift registers
• CPC Class Codes: H03K 17/9643 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H10N 30/302 Sensors
• CPC Class Codes: H10N 30/87 Electrodes or interconnections, e.g. leads or terminals

Abstract

In a method of using an ultrasonic sensor comprising a two-dimensional array of ultrasonic transducers, a plurality of ultrasonic signals are transmitted according to a beamforming pattern at a position of the two-dimensional array. The beamforming pattern focuses the plurality of ultrasonic signals to location above the two-dimensional array, wherein the beamforming pattern identifies ultrasonic transducers of the two-dimensional array that are activated during transmission of the ultrasonic signals, and wherein at least some ultrasonic transducers of the beamforming pattern are phase delayed with respect to other ultrasonic transducers of the beamforming pattern. At least one reflected ultrasonic signal is received at the position according to a receive pattern, wherein the receive pattern identifies at least one ultrasonic transducers of the two-dimensional array that is activated during the receiving. The transmitting and the receiving are repeated at a plurality of positions of the two-dimensional array.

Claims

1. A method of using an ultrasonic sensor comprising a two-dimensional array of ultrasonic transducers, the method comprising:

at a position of the two-dimensional array of ultrasonic transducers;

transmitting a plurality of ultrasonic signals according to a beamforming pattern, wherein the beamforming pattern focuses the plurality of ultrasonic signals to location above the two-dimensional array of ultrasonic transducers, wherein the beamforming pattern identifies ultrasonic transducers of the two-dimensional array of ultrasonic transducers that are activated during transmission of the ultrasonic signals, and wherein at least some ultrasonic transducers of the beamforming pattern are phase delayed with respect to other ultrasonic transducers of the beamforming pattern; and

receiving at least one reflected ultrasonic signal according to a receive pattern, wherein the receive pattern identifies at least one ultrasonic transducers of the two-dimensional array of ultrasonic transducers that is activated during the receiving; and

repeating the transmitting and the receiving at a plurality of positions of the two-dimensional array of ultrasonic transducers.

2. The method of claim 1, wherein the repeating the transmitting and the receiving at the plurality of positions of the two-dimensional array of ultrasonic transducers comprises:

performing the transmitting and the receiving for a subset of positions of the plurality of positions in parallel.

3. The method of claim 2, wherein positions of the subset of positions are separated by a plurality of inactive ultrasonic transducers.

4. The method of claim 1, wherein ultrasonic transducers identified by the beamforming pattern for the position are different than ultrasonic transducers identified by the receive pattern for the position.

5. The method of claim 1, further comprising:

for each position, directing received ultrasonic signals to a receive channel associated with the position.

6. The method of claim 1, further comprising:

storing the beamforming pattern in a first plurality of shift registers; and

storing the receive pattern in a second plurality of shift registers.

7. The method of claim 6, wherein the repeating the transmitting and the receiving at a plurality of positions of the two-dimensional array of ultrasonic transducers comprises:

shifting the beamforming pattern within the first plurality of shift registers; and

shifting the receive pattern within the second plurality of shift registers.

8. The method of claim 6, wherein storing the beamforming pattern in a first plurality of shift registers comprises:

storing a plurality of instances of the beamforming pattern in the first plurality of shift registers.

9. The method of claim 6, wherein storing the receive pattern in a second plurality of shift registers comprises:

storing a plurality of instances of the receive pattern in the second plurality of shift registers.

10. The method of claim 1, further comprising:

for each position, generating a pixel of an image based on the at least one reflected ultrasonic signal.

11. The method of claim 10, further comprising:

generating the image based on the pixel generated at each position.

12. An ultrasonic sensor comprising:

a two-dimensional array of ultrasonic transducers;

a first plurality of shift registers for storing a beamforming pattern of a beamforming space, wherein the beamforming pattern identifies ultrasonic transducers of the two-dimensional array of ultrasonic transducers that are activated during a transmit operation for transmitting a plurality of ultrasonic signals, wherein the beamforming pattern focuses the plurality of ultrasonic signals to a location above the two-dimensional array of ultrasonic transducers, and wherein at least some ultrasonic transducers of the beamforming pattern are phase delayed with respect to other ultrasonic transducers of the beamforming pattern;

a second plurality of shift registers for storing a receive pattern of the beamforming space, wherein the receive pattern identifies at least one ultrasonic transducers of the two-dimensional array of ultrasonic transducers that is activated during a receive operation for receiving at least one reflected ultrasonic signal; and

an array controller configured to control activation of ultrasonic transducers during the transmit operation according to the beamforming pattern and during the receive operation according to the receive pattern, the array controller configured to shift a position of the beamforming pattern within the first plurality of shift registers and to shift a position of the receive pattern within the second plurality of shift registers, such that the beamforming pattern and the receive pattern moves within and relative to the two-dimensional array of ultrasonic transducers, the array controller configured to repeat the transmit operation and the receive operation at a plurality of positions of the two-dimensional array of ultrasonic transducers.

13. The ultrasonic sensor of claim 12, wherein the ultrasonic transducers are Piezoelectric Micromachined Ultrasonic Transducer (PMUT) devices.

14. The ultrasonic sensor of claim 13, wherein the PMUT devices comprise an interior support structure.

15. The ultrasonic sensor of claim 12, further comprising:

a signal generator configured to generate the plurality of ultrasonic signals, wherein each ultrasonic signal of the plurality of ultrasonic signals has a different phase delay relative to other ultrasonic signals of the plurality of ultrasonic signals.

16. The ultrasonic sensor of claim 12, wherein the first plurality of shift registers is configured to store a plurality of instances of the beamforming pattern corresponding to a subset of positions of the plurality of positions of the two-dimensional array of ultrasonic transducers, such that the transmit operation is performed at each position of the subset of positions in parallel.

17. The ultrasonic sensor of claim 16, wherein the second plurality of shift registers is configured to store a plurality of instances of the receive pattern corresponding to the subset of positions of the plurality of positions of the two-dimensional array of ultrasonic transducers, such that the receive operation is performed at each position of the subset of positions in parallel.

18. The ultrasonic sensor of claim 12, further comprising:

a plurality of receive channel inputs, where each receive channel input of the plurality of receive channel inputs is associated with a sub-array of ultrasonic transducers of the two-dimensional array of ultrasonic transducers.

19. The ultrasonic sensor of claim 18, further comprising:

switches at boundary regions between adjacent sub-arrays, wherein the switches are controlled to direct a received signal for an ultrasonic transducer to a receive channel of an associated sub-array of ultrasonic transducers during the receive operation.

20. A non-transitory computer-readable storage medium comprising instructions which when executed on one or more data processors, cause the one or more data processors to perform a method of using an ultrasonic sensor comprising a two-dimensional array of ultrasonic transducers, the method comprising:

at a position of the two-dimensional array of ultrasonic transducers;

transmitting a plurality of ultrasonic signals according to a beamforming pattern, wherein the beamforming pattern focuses the plurality of ultrasonic signals to a location above the two-dimensional array of ultrasonic transducers, wherein the beamforming pattern identifies ultrasonic transducers of the two-dimensional array of ultrasonic transducers that are activated during transmission of the ultrasonic signals, and wherein at least some ultrasonic transducers of the beamforming pattern are phase delayed with respect to other ultrasonic transducers of the beamforming pattern; and

receiving at least one reflected ultrasonic signal according to a receive pattern, wherein the receive pattern identifies at least one ultrasonic transducers of the two-dimensional array of ultrasonic transducers that is activated during the receiving; and

repeating the transmitting and the receiving at a plurality of positions of the two-dimensional array of ultrasonic transducers, wherein the transmitting and the receiving for a subset of positions of the plurality of positions are performed in parallel.