Directional speaker system and method

• US 10,284,994 B2
• Filed: 03/24/2017
• Issued: 05/07/2019
• Est. Priority Date: 09/26/2016
• Status: Active Grant

• Current Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Inventors: Alexandropoulos, Alexios
• Primary Examiner(s): Paul, Disler
• Application Number:
  US15/468,711
• Publication Number:
  US 20180091916A1
• Time in Patent Office: 774 Days
• Field of Search: 381 77, 381 81- 83, 381300, 381306
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: H04R 2203/12 Beamforming aspects for stereophonic sound reproduction with loudspeaker arrays
• CPC Class Codes: H04R 2499/15 Transducers incorporated in visual displaying devices, e.g. televisions, computer displays, laptops
• CPC Class Codes: H04R 29/002 Loudspeaker arrays
• CPC Class Codes: H04R 29/008 Visual indication of individual signal levels visual indication of stereophonic sound image H04S7/40
• CPC Class Codes: H04R 3/12 for distributing signals to two or more loudspeakers specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04S 3/002 Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution control circuits for electronic adaptation of the sound field H04S7/30
• CPC Class Codes: H04S 7/303 Tracking of listener position or orientation

Abstract

A directional loudspeaker system has a loudspeaker arrangement configured to generate N audio signals. A time-of-flight sensor arrangement is configured to detect a location of a user. A controller is configured to use information from the time-of-flight sensor arrangement about the location of the user to control the delay such that the N audio signals constructively interfere at the location of the user.

Claims

1. A directional loudspeaker system comprising:

a plurality of loudspeakers configured to generate N directional audio signals, wherein the N directional audio signals are such that at least one directional audio signal of the N directional audio signals has a delay with respect to at least one other directional audio signal, wherein N is an integer equal or greater than 2, wherein the N directional audio signals comprise sound waves having a common frequency in an audible frequency spectrum, wherein the plurality of loudspeakers are configured to focus the N directional audio signals at a first location, and wherein the plurality of loudspeakers are spatially separated from one another;

a time-of-flight sensor arrangement comprising a plurality of optical time-of-flight sensors, wherein each of the plurality of loudspeakers includes one of the plurality of optical time-of-flight sensors, wherein the plurality of optical time-of-flight sensors is configured to measure a plurality of distance values comprising respective distance values measured from the first location to each of the plurality of loudspeakers; and

a controller configured to use the plurality of distance values from the time-of-flight sensor arrangement to determine N−

1 delays by subtracting a result of dividing a difference between pairs of distance values by a speed of sound from an inverse of the common frequency such that the N directional audio signals constructively interfere at the first location, wherein the constructive interference generates an audio signal having an amplitude greater than the N directional audio signals and the common frequency.

2. The directional loudspeaker system according to claim 1, wherein each of the optical time-of-flight sensors comprises a single photon avalanche diode (SPAD).

3. The directional loudspeaker system according to claim 1, wherein each of the optical time-of-flight sensors comprises a field-of-view, the directional loudspeaker system having an active area in which the N directional audio signals constructively interfere, wherein at least a part of each field-of-view of each time-of-flight sensor overlies the active area.

4. The directional loudspeaker system according to claim 1, wherein the controller is configured to use information from the time-of-flight sensor arrangement to track movement of a moving object and to correspondingly control the delay such that the N directional audio signals constructively interfere at the first location as the moving object moves.

5. The directional loudspeaker system according to claim 4, wherein a content of the N directional audio signals is dependent on a position of the moving object.

6. The directional loudspeaker system according to claim 1, wherein N is such that each of the N directional audio signals is individually sub-audible.

7. The directional loudspeaker system according to claim 1, further comprising a display arrangement configured to display video content associated with the N directional audio signals.

8. The directional loudspeaker system according to claim 1, wherein the N is equal to two, wherein one of the plurality of loudspeakers is spatially separated from another of the plurality of loudspeakers.

9. A directional loudspeaker method comprising:

determining a plurality of distance values comprising respective distance values measured from a first location to each of a plurality of optical time-of-flight sensors using a time-of-flight sensor arrangement comprising the plurality of optical time-of-flight sensors, wherein each of the plurality of optical time-of-flight sensors is configured to measure a time-of-flight information between itself and the first location;

using the plurality of distance values from the time-of-flight sensor arrangement, for each of N directional audio signals comprising sound waves having a common frequency, determining N−

1 delays by subtracting a result of dividing a difference between pairs of distance values by a speed of sound from an inverse of the common frequency, wherein N is an integer equal or greater than 2;

transmitting the N directional audio signals having a common frequency in an audible frequency spectrum towards the first location, wherein the N directional audio signals are such that each audio directional signal of the N directional audio signals has one of the N−

1 delays with respect to at least one other, and wherein each of the N transmitted directional audio signals are transmitted from spatially separated locations; and

at the first location, the delay causing generation of an audio signal having an amplitude greater than the N directional audio signals and the common frequency.

10. The method according to claim 9, wherein transmitting the N directional audio signals comprises generating the N directional audio signals using a plurality of loudspeakers that are spatially separated.

11. The method according to claim 9, further comprising using information from the time-of-flight sensor arrangement to track movement of a moving object and to correspondingly control the delay such that the N directional audio signals constructively interfere at the first location of as the moving object moves.

12. The method according to claim 9, wherein N is such that each of the N directional audio signals is individually sub-audible.

13. The method according to claim 9, further comprising displaying video content associated with the N directional audio signals.

14. The method according to claim 9, wherein a content of the N directional audio signals is dependent on a position of a moving object.

15. The method according to claim 9, wherein the N is equal to two, wherein transmitting the N directional audio signals comprises transmitting from a first speaker location and a second speaker location that are spatially separated from each other.

16. A directional loudspeaker system comprising:

a first directional loudspeaker configured to directionally transmit a first sub-audible sound wave in an audible frequency spectrum from a first location towards a second location;

a second directional loudspeaker configured to directionally transmit a second sub-audible sound wave in the audible frequency spectrum from a third location towards the second location, wherein the first location and the third location are spatially separated;

a first optical time-of-flight sensor configured to determine a first distance between the first location and the second location;

a second optical time-of-flight sensor configured to determine a second distance between the third location and the second location, the first distance being different from the second distance; and

a controller configured to generate a phase difference between the first sub-audible sound wave and the second sub-audible sound wave that are being emitted so that the first sub-audible sound wave and the second sub-audible sound wave constructively interfere at the second location using a difference between the first distance and the second distance, wherein the constructive interference generates an audio signal having an amplitude greater than the first sub-audible sound wave and the second sub-audible sound wave.

17. The directional loudspeaker system according to in claim 16, wherein each of the first and the second optical time-of-flight sensors comprises a field-of-view, the directional loudspeaker system having an active area in which the first and the second sub-audible sound waves constructively interfere, wherein at least a part of each field-of-view of each of the first and the second optical time-of-flight sensors overlies the active area.

18. The directional loudspeaker system according to claim 16, wherein the controller is configured to use information from the first and the second optical time-of-flight sensors to track movement of a moving object and to correspondingly control a phase difference between the first and the second sub-audible sound waves such that the first and the second sub-audible sound waves constructively interfere at the first location as the moving object moves.

19. The directional loudspeaker system according to claim 16, further comprising a display configured to display video content associated with the first and the second sub-audible sound waves.

20. The directional loudspeaker system according to claim 16, wherein each of the first and the second optical time-of-flight sensors comprises a single photon avalanche diode (SPAD).

21. The directional loudspeaker system according to in claim 16, wherein the controller is configured to generate the phase difference so that the first sub-audible sound wave and the second sub-audible sound wave are configured to reach the first location with no phase difference.

22. A method of transmitting audio, the method comprising:

determining a first distance between a first speaker position and a first hearing position using a first optical sensor at the first speaker position;

determining a second distance between the first speaker position and a second hearing position using the first optical sensor at the first speaker position;

determining a third distance between a second speaker position and the first hearing position using a second optical sensor at the second speaker position;

determining a fourth distance between the second speaker position and the second hearing position using the second optical sensor at the second speaker position;

directionally transmitting a first sub-audible audio signal from a first speaker location to a first hearing position;

directionally transmitting a second sub-audible audio signal from the first speaker location to a second hearing position;

based on a difference between the first and the third distances, directionally transmitting a third sub-audible audio signal from a second speaker location to the first hearing position, wherein the first sub-audible audio signal and the third sub-audible audio signal have a first frequency, wherein the first sub-audible audio signal and the third sub-audible audio signal constructively interfere at the first hearing position, wherein the constructive interference at the first hearing position generates a first audible audio signal having an amplitude greater than the first and the third sub-audible audio signals and the first frequency; and

based on a difference between the second and the fourth distances, directionally transmitting a fourth sub-audible audio signal from the second speaker location to the second hearing position, wherein the second sub-audible audio signal and the fourth sub-audible audio signal have a second frequency, wherein the second sub-audible audio signal and the fourth sub-audible audio signal constructively interfere at the second hearing position wherein the constructive interference at the second hearing position generates a second audible audio signal having an amplitude greater than the second and the fourth sub-audible audio signals and the second frequency.

23. The method according to claim 22, wherein the first, the second, the third, and the fourth sub-audible audio signals are simultaneously transmitted.

24. The method according to claim 22, wherein the first sub-audible audio signal and the third sub-audible audio signal have a first phase difference so as reach the first hearing position at the same time with no phase difference, and wherein the second sub-audible audio signal and the fourth sub-audible audio signal have a second phase difference so as to reach the second hearing position at the same time with no phase difference.