Ultrasonic sensor

• US 7,775,110 B2
• Filed: 09/20/2007
• Issued: 08/17/2010
• Est. Priority Date: 09/22/2006
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation, Nippon Soken, Inc. (DENSO Corporation)
• Original Assignee: DENSO Corporation, Nippon Soken, Inc. (DENSO Corporation)
• Inventors: Watanabe, Kazuaki, Yoshioka, Tetsuo, Yoshida, Takahiko, Matsuoka, Hisanaga, Okuda, Yasuyuki, Sugiura, Makiko
• Primary Examiner(s): Williams; Hezron
• Assistant Examiner(s): Shah; Samir M
• Application Number:
  US11/902,366
• Publication Number:
  US 20080072675A1
• Time in Patent Office: 1,062 Days
• Field of Search: 735/84, 735/87, 735/91, 735/96, 736/17, 736/27, 736/49
• US Class Current: 73/627
• CPC Class Codes: G01H 11/08 using piezoelectric devices

Abstract

An ultrasonic sensor includes an ultrasonic detecting element, an acoustic matching member, and an oscillation damping member. The ultrasonic detecting element detects an ultrasonic wave. The acoustic matching member has a receiving surface that is adapted on a side of the certain object to be exposed to a space, in which the detected body exists. The receiving surface receives the ultrasonic wave reflected by the detected body. The acoustic matching member is made of a material having an acoustic impedance larger than that of air and smaller than that of the ultrasonic detecting element. The oscillation damping member is disposed between an attachment portion and the acoustic matching member. The attachment portion is adapted for attaching the ultrasonic sensor to the certain object. The oscillation damping member damps transmission of oscillation from the certain object to the acoustic matching member.

Claims

1. An ultrasonic sensor attached to a certain object, the sensor comprising:

an ultrasonic detecting element that detects an ultrasonic wave, which is transmitted by an ultrasonic transmitting element that transmits the ultrasonic wave, and which is reflected by a detected body;

an acoustic matching member that has a receiving surface that is adapted on a side of the certain object to be exposed to a space, in which the detected body exists, the receiving surface receiving the ultrasonic wave reflected by the detected body, the acoustic matching member transmitting the ultrasonic wave received by the receiving surface to the ultrasonic detecting element, which is attached to an opposing surface of the acoustic matching member opposite the receiving surface, the acoustic matching member being made of a material having an acoustic impedance larger than that of air and smaller than that of the ultrasonic detecting element; and

an oscillation damping member that is disposed between an attachment portion and the acoustic matching member, the attachment portion being adapted for attaching the ultrasonic sensor to the certain object, the oscillation damping member damping transmission of oscillation from the certain object to the acoustic matching member, wherein

the acoustic matching member has a contact face that contacts with the oscillation damping member, part of the contact face having one of a projection portion, which projects toward the oscillation damping member, and a recess portion, the oscillation damping member having a corresponding one of a recess portion and a projection portion, the corresponding one of the recess portion and the projection portion of the oscillation damping member having a shape for engaging with the one of the projection portion and the recess portion of the acoustic matching member.

2. The ultrasonic sensor according to claim 1, wherein the oscillation damping member is made of a material having a degree of elasticity smaller than that of the acoustic matching member.

3. The ultrasonic sensor according to claim 2, wherein the degree of elasticity of the oscillation damping member is equal to or less than 1 MPa.

4. The ultrasonic sensor according to claim 3, wherein the oscillation damping member has a contact length of equal to or less than 2 mm in a direction from the receiving surface toward the ultrasonic detecting element, the oscillation damping member being in contact with the acoustic matching member over the contact length.

5. The ultrasonic sensor according to claim 2, wherein the degree of elasticity of the oscillation damping member is equal to or less than 3 MPa.

6. The ultrasonic sensor according to claim 1, wherein the oscillation damping member is made of a material having the acoustic impedance smaller than that of the acoustic matching member.

7. The ultrasonic sensor according to claim 1, wherein the oscillation damping member is made of a silicone rubber.

8. The ultrasonic sensor according to claim 1, wherein the oscillation damping member is provided only at a vicinity of a node portion of a standing wave generated to the acoustic matching member.

9. The ultrasonic sensor according to claim 1, wherein the oscillation damping member is provided to cover the receiving surface of the acoustic matching member.

10. The ultrasonic sensor according to claim 1, wherein the acoustic matching member is fixed to the oscillation damping member by an adhesive material.

11. The ultrasonic sensor according to claim 1, wherein the oscillation damping member is provided integrally with the acoustic matching member by a two-color molding.

12. The ultrasonic sensor according to claim 11, wherein the two-color molding is performed by using an elastomer.

13. The ultrasonic sensor according to claim 1, wherein the acoustic matching member is adapted to generate a standing wave inside thereof due to the ultrasonic wave received by the receiving surface.

14. The ultrasonic sensor according to claim 1, wherein the acoustic matching member is made of a polycarbonate based resin.

15. The ultrasonic sensor according to claim 14, wherein at least the receiving surface of the acoustic matching member is coated with a metallic deposition.

16. The ultrasonic sensor according to claim 1, wherein the acoustic matching member has the acoustic impedance, which increases in a direction from the receiving surface toward the opposing surface.

17. The ultrasonic sensor according to claim 16, wherein:

the acoustic matching member is made of a resin material and of a filler, which is added to the resin material; and

an additional amount of the tiller added to the resin material increases in the direction from the receiving surface toward the opposing surface.

18. The ultrasonic sensor according to claim 16, wherein the acoustic matching member is formed by laminating a plurality of resin based materials, each of which has a different acoustic impedance from each other, the plurality of resin based materials being laminated onto one another in an ascending order of the acoustic impedance in the direction from the receiving surface toward the opposing surface.

19. The ultrasonic sensor according to claim 1, wherein the acoustic matching member has a distance between opposing side edges of the receiving surface, the distance being equal to or less than a half of the wavelength of the ultrasonic wave transmitting in air.

20. The ultrasonic sensor according to claim 1, wherein the acoustic matching member is provided integrally with the oscillation damping member by a rubber based material.

21. The ultrasonic sensor according to claim 1, wherein the receiving surface has an area larger than an area of a surface of the ultrasonic detecting element, the surface of the ultrasonic detecting element being in contact with the opposing surface.

22. The ultrasonic sensor according to claim 1, wherein the ultrasonic detecting element has a surface, through which the ultrasonic detecting element is attached to the opposing surface, part of the surface of the ultrasonic detecting element being provided outside an outer edge of the opposing surface.

23. The ultrasonic sensor according to claim 1, wherein the ultrasonic detecting element is made of a lead zirconate titanate based material.

24. The ultrasonic sensor according to claim 1, further comprising a coating layer that covers at least a part of the receiving surface and covers a surface of the oscillation damping member, the surface of the oscillation damping member being exposed to the space, in which the detected body exists.

25. The ultrasonic sensor according to claim 24, wherein the coating layer is made of a material having a degree of elasticity smaller than that of the acoustic matching member.

26. The ultrasonic sensor according to claim 24, wherein:

the coating layer has the degree of elasticity equal to or less than 1/10 of the degree of elasticity of the acoustic matching member; and

the coating layer has a thickness equal to or less than 0.1 mm.

27. The ultrasonic sensor according to claim 24, wherein the coating layer is adapted to have a resonance frequency substantially equal to that of the acoustic matching member.

28. The ultrasonic sensor according to claim 24, wherein:

the coating layer has a degree of elasticity equal to or less than a degree of elasticity of the oscillation damping member; and

the coating layer covers an entire surface of the acoustic matching member.

29. The ultrasonic sensor according to claim 1, wherein the certain object is a vehicle.

30. The ultrasonic sensor according to claim 29, wherein the attachment portion is provided to one of a head lamp cover, a rear lamp cover, a turn signal cover, a back lamp cover, a door mirror, and a bumper of the vehicle.

31. An ultrasonic sensor attached to a certain object, the sensor comprising:

an ultrasonic detecting element that detects an ultrasonic wave, which is transmitted by an ultrasonic transmitting element that transmits the ultrasonic wave, and which is reflected by a detected body;

an acoustic matching member that has a receiving surface that is adapted on a side of the certain object to be exposed to a space, in which the detected body exists, the receiving surface receiving the ultrasonic wave reflected by the detected body, the acoustic matching member transmitting the ultrasonic wave received by the receiving surface to the ultrasonic detecting element, which is attached to an opposing surface of the acoustic matching member opposite the receiving surface, the acoustic matching member being made of a material having an acoustic impedance larger than that of air and smaller than that of the ultrasonic detecting element; and

an oscillation damping member that is disposed between an attachment portion and the acoustic matching member, the attachment portion being adapted for attaching the ultrasonic sensor to the certain object, the oscillation damping member damping transmission of oscillation from the certain object to the acoustic matching member, wherein

the acoustic matching member is one of a plurality of acoustic matching members;

the ultrasonic detecting element is one of a plurality of ultrasonic detecting elements for making a pair with a corresponding one of the plurality of acoustic matching members;

a plurality of pairs of the acoustic matching member and the ultrasonic detecting element is arranged in an array; and

the oscillation damping member is adapted between each of the acoustic matching members and is also adapted between each of the acoustic matching members and the attachment portion.

32. The ultrasonic sensor according to claim 31, wherein the acoustic matching members are arranged such that a distance between a center portion of one of the acoustic matching members and a center portion of a corresponding one of the acoustic matching members is equal to or substantially equal to a half of a wavelength of the ultrasonic wave transmitting in air.