Acoustic Wave Sensor

• US 20080291784A1
• Filed: 07/27/2005
• Published: 11/27/2008
• Est. Priority Date: 07/27/2004
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Asahi Matsushita Electric Works Ltd. (Panasonic Holdings Corporation)
• Inventors: Yamanaka, Hiroshi, Watabe, Yoshifumi, Kawada, Hiroshi, Honda, Yoshiaki, Sawada, Kazuo, Kitada, Kousaku, Goto, Hiromichi, Ohtsuka, Tomoo
• Granted Patent: US 8,254,209 B2
• Time in Patent Office: Days
• US Class Current: 367/99
• CPC Class Codes: B06B 1/02 making use of electrical energy B06B1/18, B06B1/20 take precedence
• CPC Class Codes: G01H 11/06 by electric means
• CPC Class Codes: G01L 9/0025 with acoustic surface waves
• CPC Class Codes: G01S 3/808 using transducers spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
• CPC Class Codes: G01S 7/524 Transmitters
• CPC Class Codes: G01S 7/526 Receivers

Abstract

In an acoustic wave sensor for detecting a distance to an object and an orientation where the object is located with using acoustic waves, an acoustic wave generating device generating an acoustic wave by applying thermal impact to the air with no mechanical vibration is used as a wave transmitting device, and an electric capacitance microphone converting variation of pressure due to acoustic wave to variation of an electric signal is used as each wave receiving device. Therefore, dead zone caused by reverberation component included in the acoustic wave transmitted from the wave transmitting device and dead zone caused by reverberation component included in wave receiving signals outputted from the wave receiving devices can be shortened and angular sensitivity of the acoustic wave sensor can be increased, in comparison with a conventional acoustic wave sensor using piezoelectric devices as the wave transmitting device and the wave receiving devices.

Claims

1. An acoustic wave sensor comprising:

a wave transmitter having a wave transmitting device which can transmit acoustic wave and a driving circuit for driving the wave transmitting device; and

a wave receiver having wave receiving devices directly receive acoustic wave transmitted from the wave transmitter or receive acoustic wave transmitted from the wave transmitter and reflected by an object, and convert received acoustic wave to wave receiving signals of electric signals, thereby at least one of a distance to the wave transmitter or the object and an orientation where the wave transmitter or the object is located can be detected;

wherein

the wave transmitting device is constituted by an acoustic wave generator generating the acoustic wave by applying thermal impacts to air.

5. The acoustic wave sensor in accordance with claim 1, wherein

the acoustic wave generating device comprises a heating conductor of a thin film, and generates an acoustic wave by applying thermal impact to air due to temperature change of the heating conductor corresponding to energization to the heating conductor.

6. The acoustic wave sensor in accordance with claim 5, wherein

the acoustic wave generating device comprises a base substrate, a heating conductor layer serving as the heating conductor formed on at least a surface of the base substrate, and a thermal insulation layer disposed between the base substrate and the heating conductor layer.

7. The acoustic wave sensor in accordance with claim 1, wherein

the acoustic wave generating device has a pair of electrodes facing each other in an air, and generates an acoustic wave by applying thermal impact to the air due to generation of spark discharge between the electrodes by applying a predetermined voltage between the electrodes.

8. The acoustic wave sensor in accordance with claim 1, wherein

the wave receiver comprises a plurality of wave receiving devices arranged on the same plane, and has a function for detecting an orientation from which acoustic waves arrive at the wave receiver on basis of a phase difference of wave receiving signals outputted from the wave receiving devices and an arrangement of the wave receiving devices.

2. An acoustic wave sensor comprising:

a wave transmitter having a wave transmitting device which can transmit acoustic wave and a driving circuit for driving the wave transmitting device; and

a wave receiver having wave receiving devices directly receive acoustic wave transmitted from the wave transmitter or receive acoustic wave transmitted from the wave transmitter and reflected by an object, and convert received acoustic wave to wave receiving signals of electric signals, thereby at least one of a distance to the wave transmitter or the object and an orientation where the wave transmitter or the object is located can be detected;

wherein

each of the wave receiving devices is constituted by an electrical capacitance microphone converting variation of pressure due to acoustic pressure of the acoustic wave to variation of electric signal.

9. The acoustic wave sensor in accordance with claim 2, wherein

the acoustic wave generating device comprises a heating conductor of a thin film, and generates an acoustic wave by applying thermal impact to air due to temperature change of the heating conductor corresponding to energization to the heating conductor.

12. The acoustic wave sensor in accordance with claim 2, wherein

the acoustic wave generating device has a pair of electrodes facing each other in an air, and generates an acoustic wave by applying thermal impact to the air due to generation of spark discharge between the electrodes by applying a predetermined voltage between the electrodes.

15. The acoustic wave sensor in accordance with claim 2, wherein

the wave receiver comprises a plurality of wave receiving devices arranged on the same plane, and has a function for detecting an orientation from which acoustic waves arrive at the wave receiver on basis of a phase difference of wave receiving signals outputted from the wave receiving devices and an arrangement of the wave receiving devices.

3. An acoustic wave sensor comprising:

a wave transmitter having a wave transmitting device which can transmit acoustic wave and a driving circuit for driving the wave transmitting device; and

a wave receiver having wave receiving devices directly receive acoustic wave transmitted from the wave transmitter or receive acoustic wave transmitted from the wave transmitter and reflected by an object, and convert received acoustic wave to wave receiving signals of electric signals, thereby at least one of a distance to the wave transmitter or the object and an orientation where the wave transmitter or the object is located can be detected;

wherein

a Q factor of resonance characteristic of the wave transmitting device is equal to or smaller than 10.

10. The acoustic wave sensor in accordance with claim 3, wherein

the acoustic wave generating device comprises a heating conductor of a thin film, and generates an acoustic wave by applying thermal impact to air due to temperature change of the heating conductor corresponding to energization to the heating conductor.

13. The acoustic wave sensor in accordance with claim 3, wherein

the acoustic wave generating device has a pair of electrodes facing each other in an air, and generates an acoustic wave by applying thermal impact to the air due to generation of spark discharge between the electrodes by applying a predetermined voltage between the electrodes.

16. The acoustic wave sensor in accordance with claim 3, wherein

the wave receiver comprises a plurality of wave receiving devices arranged on the same plane, and has a function for detecting an orientation from which acoustic waves arrive at the wave receiver on basis of a phase difference of wave receiving signals outputted from the wave receiving devices and an arrangement of the wave receiving devices.

4. An acoustic wave sensor comprising:

a wave transmitter having a wave transmitting device which can transmit acoustic wave and a driving circuit for driving the wave transmitting device; and

a wave receiver having wave receiving devices directly receive acoustic wave transmitted from the wave transmitter or receive acoustic wave transmitted from the wave transmitter and reflected by an object, and convert received acoustic wave to wave receiving signals of electric signals, thereby at least one of a distance to the wave transmitter or the object and an orientation where the wave transmitter or the object is located can be detected;

wherein

a Q factor of resonance characteristic of each wave receiving device is equal to or smaller than 10.

11. The acoustic wave sensor in accordance with claim 4, wherein

the acoustic wave generating device comprises a heating conductor of a thin film, and generates an acoustic wave by applying thermal impact to air due to temperature change of the heating conductor corresponding to energization to the heating conductor.

14. The acoustic wave sensor in accordance with claim 4, wherein

the acoustic wave generating device has a pair of electrodes facing each other in an air, and generates an acoustic wave by applying thermal impact to the air due to generation of spark discharge between the electrodes by applying a predetermined voltage between the electrodes.

17. The acoustic wave sensor in accordance with claim 4, wherein

the wave receiver comprises a plurality of wave receiving devices arranged on the same plane, and has a function for detecting an orientation from which acoustic waves arrive at the wave receiver on basis of a phase difference of wave receiving signals outputted from the wave receiving devices and an arrangement of the wave receiving devices.