JP2009065380A - Ultrasonic sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic sensor whose manufacturing step can be simplified and which can be made compact. <P>SOLUTION: The ultrasonic sensor includes: a hollow-shaped main body part 11; a vibrating part 12 provided at one end of the main body part 11 to transmit and receive an ultrasonic wave; a directivity adjusting part 14 for adjusting the directivity of the ultrasonic wave; and a piezoelectric element 13 disposed in the vibrating part 12 inside the main body part 11, wherein the directivity adjusting part 14 is provided on the opposite side from the side at which the piezoelectric element 13 is disposed in the vibrating part 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic sensor, and more particularly to an ultrasonic sensor having directivity.

  The ultrasonic sensor performs sensing using ultrasonic waves. The ultrasonic sensor intermittently transmits an ultrasonic pulse signal from a piezoelectric element, and detects an object by receiving a reflected wave from an obstacle present around the piezoelectric element.

  Of this type of ultrasonic sensor, an ultrasonic sensor used for in-vehicle use is attached to a vehicle bumper or the like in order to monitor the periphery of the vehicle. For this reason, in order to reliably detect obstacles around the vehicle, the directivity of the ultrasonic sensor is widened in the horizontal direction with respect to the road surface, and the ultrasonic sensor is designed not to detect the road surface in the direction perpendicular to the road surface. It is necessary to narrow the directivity.

  Patent Document 1 describes an ultrasonic sensor having directivity for in-vehicle use. The ultrasonic sensor described in Patent Document 1 will be described with reference to FIG.

A thick part 62 a and a thin part 62 b are provided on the bottom 62 of the case body 61 having the hollow part 64. The thin part 62b has a substantially crescent shape, and is provided on both sides of the thick part 62a. A piezoelectric element 63 is fixed to the inner surface of the thick portion 62a. The case body 61 is formed with a thick portion 62a and a thin portion 62b on the bottom portion 62, thereby providing a direction in which the thin portion 62b is provided rather than the inner diameter X of the case body 61 in the direction in which the thick portion 62a is provided. The case body 61 has a longer inner diameter Y. In the ultrasonic sensor 60, the directivity of ultrasonic waves can be adjusted by the shape of the case body 61.
JP 2000-32594 A

  However, in the ultrasonic sensor described in Patent Document 1, in order to adjust the directivity, the shape of the case body 61 needs to have an inner diameter Y longer than the inner diameter X. For this reason, the process which forms the case body 61 becomes complicated. Even when the case body 61 is downsized until the inner diameter X becomes substantially the same as the diameter of the piezoelectric element, the case body 61 needs to be formed in a size including the inner diameter Y in the hollow portion 64. For this reason, there is a limit to miniaturization of the ultrasonic sensor. Further, when the case body 61 is downsized, it is difficult to assemble the piezoelectric element 63 at an appropriate position in the hollow portion 64.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an ultrasonic sensor that can simplify the manufacturing process and can be miniaturized.

  In order to solve the above problems, the present invention is characterized by having the following parts.

The ultrasonic sensor according to the invention of claim 1 is:
A hollow body (11);
A vibration part (12) provided at one end of the main body part (11) for transmitting and receiving ultrasonic waves;
A directivity adjusting unit (14) for adjusting the directivity of the ultrasonic wave;
An ultrasonic sensor having a piezoelectric element (13) disposed in the vibration section (12) inside the main body section (11),
The directivity adjusting part (14) is provided on the vibration part (12) on the opposite side of the piezoelectric element (13).

The invention according to claim 2
The ultrasonic sensor according to claim 1,
The directivity adjusting portion (14) is formed by providing a thickness to the vibrating portion (12).

The invention described in claim 3
The ultrasonic sensor according to claim 1 or 2,

The directivity adjusting section (14) is provided outside a region facing the piezoelectric element (12).

The invention according to claim 4
The ultrasonic sensor according to any one of claims 1 to 3,
The main body (11) has a cylindrical shape.

  In addition, the said reference code is a reference to the last, and description of a claim is not limited by this.

  ADVANTAGE OF THE INVENTION According to this invention, a manufacturing process can be simplified and the ultrasonic sensor which can aim at size reduction can be provided.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  1 and 2 are diagrams for explaining the basic configuration of the present invention. FIG. 1 is a perspective view of the ultrasonic sensor according to the present invention as viewed from above. FIG. 2 is an ultrasonic wave according to the present invention. It is the perspective view seen from the lower part of a sensor.

  The ultrasonic sensor 10 includes a main body part 11, a vibration part 12, a piezoelectric element 13, a directivity adjustment part 14, and the like.

  The main body 11 has a bottomed cylindrical shape made of a metal material such as aluminum, and includes a hollow portion 15 having one end opened. The vibration part 12 is a vibration plate that forms the bottom of the main body part 11, and is provided at one end opposite to the opening side to transmit and receive ultrasonic waves. The piezoelectric element 13 is fixed inside the hollow portion 15 on the vibrating portion 12 with a conductive adhesive or the like. The directivity adjusting unit 14 is disposed on the vibration unit 12 on the side opposite to the side where the piezoelectric element 13 is disposed, and adjusts the directivity of the ultrasonic wave transmitted from the ultrasonic sensor 10.

  In the ultrasonic sensor 10 of the present invention, the propagation of the vibration of the vibration unit 12 generated by the piezoelectric element 13 is suppressed by the directivity adjustment unit 14 so that the transmitted ultrasonic wave has directivity.

  The directivity adjusting unit 14 will be described in detail below.

  The ultrasonic sensor 10 of the present invention utilizes ultrasonic characteristics that the directivity becomes sharper as the area of the vibration surface is larger with respect to the wavelength. In the ultrasonic sensor 10, the directivity adjustment unit 14 provided in the vibration unit 12 forms a region for suppressing the propagation of vibration of the vibration unit 12 to adjust the vibration area, and is transmitted from the ultrasonic sensor 10. Adjust the directivity of ultrasound.

  The directivity adjusting unit 14 is formed by providing a thickness to the vibrating unit 12 as shown in FIGS. 2 and 3C. The directivity adjusting unit 14 may be formed integrally with the vibrating unit 12, for example. The directivity adjusting unit 14 is formed separately from the vibrating unit 12 and may be attached to the vibrating unit 12. Moreover, the main body part 11 and the vibration part 12 are integrally formed, and the directivity adjusting part 14 may be attached to the vibration part 12 integrally formed with the main body part 11.

  In the ultrasonic sensor 10, vibration transmitted from the piezoelectric element 13 to the vibration unit 12 is attenuated by the directivity adjustment unit 14 formed by providing the vibration unit 12 with a thickness. The ultrasonic sensor 10 transmits the vibration propagated from the piezoelectric element 13 as an ultrasonic wave in a region where the directivity adjustment unit 14 of the vibration unit 12 is not provided.

  As described above, the ultrasonic sensor 10 according to the present invention is provided with the directivity adjusting unit 14 to attenuate the vibration transmitted from the piezoelectric element 13 to the vibrating unit 12, and the piezoelectric element 13 to the vibrating unit 12. A vibration propagation region for propagating the propagated vibration as it is is formed. That is, in the ultrasonic sensor 10 of the present invention, the directivity adjustment unit 14 is added from the outside of the main body unit 11 to form a vibration attenuation region and a vibration propagation region, and the vibration area in the vibration unit 12 is adjusted to be super The sound wave has directivity.

  For this reason, according to the ultrasonic sensor 10 of the present invention, it is not necessary to process the shapes of the main body 11 and the vibrating part 12 for the purpose of imparting directivity to the ultrasonic wave, and the piezoelectric element 13 is simply arranged in the vibrating part 12. The directivity adjusting unit 14 may be provided on the opposite side to the installation side. In addition, since the ultrasonic sensor 10 does not need to process the shapes of the main body 11 and the vibration part 12, for example, it can be downsized to an extent that the inner diameter of the main body 11 is substantially the same as the diameter of the piezoelectric element 13. is there.

As described above, according to the present invention, it is possible to provide an ultrasonic sensor capable of simplifying the manufacturing process and reducing the size.
(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a diagram illustrating the ultrasonic sensor according to the first embodiment, and FIG. 3A is a diagram of the ultrasonic sensor viewed from the bottom when the vibration part of the ultrasonic sensor is the bottom surface. FIG. 3B is a diagram for explaining a vibration propagation region of the ultrasonic sensor. FIG. 3C is an AA cross-sectional view for schematically explaining the internal structure of the ultrasonic sensor.

  In the ultrasonic sensor 10 of the present embodiment, a pair of directivity adjustment units 14 are arranged along the outer periphery of the piezoelectric element 13. In the ultrasonic sensor 10, the vibration attenuation region 16 and the vibration propagation region 17 are formed by forming the directivity adjusting unit 14 in the vibration unit 12. Strictly speaking, the vibration generated by the piezoelectric element 13 is also propagated from the vibration attenuation region 16, but is sufficiently smaller than the vibration propagated from the vibration propagation region 16. Does not consider this vibration.

  Here, in FIG. 3A, when the X-axis direction on the paper surface is the horizontal direction with respect to the road surface, and the Y-direction on the paper surface is the vertical direction with respect to the road surface, the vibration propagation region 17 is long in the Y direction and short in the X direction. For this reason, the ultrasonic wave transmitted from the vibration propagation region 17 in the ultrasonic sensor 10 has a wider directivity in the X direction than in the Y direction.

  Therefore, when the ultrasonic sensor 10 is used for in-vehicle use, if the X direction is arranged so as to be horizontal with the road surface, the directivity in the road surface and the horizontal direction is widened, and the directivity in the road surface and the vertical direction is narrowed. can do. Therefore, the ultrasonic sensor 10 can accurately detect an obstacle around the vehicle body without detecting the road surface.

  The directivity adjusting unit 14 may form a thickness in the vibrating unit 12 by forming a step, for example, or may be formed by providing the vibrating unit 12 with a thickness by an inclined surface. The directivity adjusting unit 14 may be formed of, for example, the same metal material as that of the main body unit 11. The directivity adjusting unit 14 may be formed of resin or the like.

  The directivity adjusting unit 14 according to the present embodiment only needs to attenuate the vibration propagated from the piezoelectric element 13 to the vibrating unit 12 and suppress the vibration propagated from the vibrating unit 12. It is not limited to this. In addition, the directivity adjusting unit 14 according to the present embodiment only needs to be able to adjust the directivity of the ultrasonic wave transmitted from the vibration propagation region 17 so as to have a wider directivity in the X direction than in the Y direction. Therefore, the arrangement position of the directivity adjustment unit 14 in the vibration unit 12 is not limited to the present embodiment.

  Next, the vibration propagation region 17 will be described with reference to FIG.

  The vibration propagation region 17 is formed by a substantially circular region 17b and a pair of substantially rectangular regions 17a extending from the region 17b in the Y direction. The vibration propagation region 17 includes the region 17b and the pair of regions 17a, so that the length Y1 of the vibration propagation region 17 is longer than the length X1. Therefore, the ultrasonic wave transmitted from the vibration propagation region 17 is an ultrasonic wave having a narrow directivity in the Y direction.

  FIG. 4 shows the directivity characteristics of the ultrasonic sensor 10 of this embodiment. It can be seen from the directivity shown in FIG. 4 that the ultrasonic sensor 10 of this example has a wide directivity in the X direction compared to the Y direction.

  Next, referring back to FIG. 3, an outline of the internal structure of the ultrasonic sensor 10 of the present embodiment will be described with reference to FIG.

  In the ultrasonic sensor 10, a terminal T <b> 1 is connected to the piezoelectric element 13, and a terminal T <b> 2 is connected to the main body 11. The piezoelectric element 13 is fixed to the main body 11 with a conductive adhesive 18. In the ultrasonic sensor 10, the piezoelectric element 13 is vibrated by applying an alternating voltage to both ends of the terminal T <b> 1 and the terminal T <b> 2, and ultrasonic pulse signals are intermittently transmitted from the vibration unit 12. In this embodiment, since the directivity adjusting unit 14 is provided outside the main body 11, the degree of freedom of wiring when the terminals T1 and T2 are provided can be increased.

  As described above, according to the present embodiment, since the directivity adjusting unit 14 is provided on the vibration unit 12 on the side opposite to the side where the piezoelectric element 13 is disposed, the shapes of the main body unit 11 and the vibration unit 12 are reduced. There is no need to process. Further, according to the present embodiment, it is not necessary to make a complicated adjustment of the arrangement position of the piezoelectric element 13 in the arrangement work of the piezoelectric element 13 in the hollow portion 15. Therefore, according to the present embodiment, the ultrasonic sensor manufacturing process can be simplified. Further, according to the present embodiment, since it is not necessary to process the inside of the main body portion 11, the main body portion 11 can be downsized to the extent that the inner diameter of the main body portion 11 is substantially the same as the diameter of the piezoelectric element 13.

Moreover, according to the present Example, since the directivity adjustment part 14 is provided in the outer side of the main-body part 11, the main-body part 11 does not become obstructive in the process at the time of attaching the directivity adjustment part 14. FIG. For this reason, even if it reduces the diameter of the main-body part 11, the process which attaches the directivity adjustment part 14 can be performed easily. Therefore, according to the present embodiment, desired directivity can be easily given to the ultrasonic wave transmitted from the ultrasonic sensor 10.
(Second embodiment)
In the following, as a second embodiment of the present invention, an example in which the inner diameter of the main body is reduced to be substantially the same as the diameter of the piezoelectric element 13 will be shown.

  FIG. 5 is a diagram for explaining the ultrasonic sensor according to the second embodiment. FIG. 5A is a diagram of the ultrasonic sensor viewed from the bottom when the vibration part of the ultrasonic sensor is the bottom. FIG. 5B is a BB cross-sectional view of the ultrasonic sensor.

  As shown in FIG. 5A, in the ultrasonic sensor 10A of the present embodiment, as shown in FIG. 5B, the inner diameter R1 of the main body 11A is made as close as possible to the diameter R2 of the piezoelectric element 13A. did. In this embodiment, the directivity adjusting unit 14A is located at a position facing the piezoelectric element 13A that is a vibration generation source. Therefore, it is preferable that the thickness for forming the directivity adjusting portion 14 </ b> A of this embodiment is thicker than that of the first embodiment in which the directivity adjusting portion 14 is disposed at a position not facing the piezoelectric element 13.

  By increasing the thickness of the directivity adjusting unit 14A, even if the directivity adjusting unit 14A is opposed to the piezoelectric element 13A, vibration propagated from the piezoelectric element 13A to the vibrating unit 12A can be further attenuated. . For this reason, propagation of vibrations can be suppressed in the vibration attenuation region 16A, and the ultrasonic waves propagated from the vibration propagation region 17A can have a narrow directivity in the Y direction. According to the present embodiment, the outer diameter R3 of the main body 11A shown in FIG. 5B can be reduced to, for example, about 8 mm.

  The directivity adjusting unit 14A according to the present embodiment only needs to be arranged at the center of the vibration unit 12A so that the vibration propagation region 16A that is longer in the Y direction than in the X direction can be configured. Therefore, the arrangement position of the directivity adjusting unit 14A is not limited to the present embodiment.

  FIG. 6 shows another embodiment of the present invention. FIG. 6A is a diagram illustrating a case where the rectangular directivity adjustment unit 14B is disposed on the vibration unit 12B. FIG. 6B illustrates that the crescent-shaped directivity adjustment unit 14C is connected to the vibration unit 12C. It is a figure which shows the case where it arrange | positions.

  As shown in FIGS. 6A and 6B, in any case, vibration attenuation regions 16B and 16C and vibration propagation regions 17B and 17C longer in the Y direction than in the X direction are formed. . Therefore, the directivity of the ultrasonic wave can be adjusted so as to have a wider directivity in the X direction than in the Y direction regardless of the shape shown in FIGS. 6 (A) and 6 (B). The same effects as those of the first embodiment and the second embodiment described above can be obtained.

  Although the present invention has been described based on each embodiment, the present invention is not limited to the requirements shown in the above embodiment. With respect to these points, the gist of the present invention can be changed without departing from the scope of the present invention, and can be appropriately determined according to the application form.

It is the perspective view seen from the upper part of the ultrasonic sensor concerning the present invention. It is the perspective view seen from the lower part of the ultrasonic sensor concerning the present invention. It is a figure explaining the ultrasonic sensor of a 1st Example. It is a figure which shows the directional characteristic of the ultrasonic sensor of a 1st Example. It is a figure explaining the ultrasonic sensor of a 2nd Example. It is a figure which shows the other Example of this invention. It is a figure explaining the ultrasonic sensor described in patent documents 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ultrasonic sensor 11 Main-body part 12 Vibration part 13 Piezoelectric element 14 Directivity adjustment part 15 Hollow part 16 Vibration attenuation area 17 Vibration propagation area

Claims (4)

A hollow body portion;
A vibration unit that is provided at one end of the main body and transmits and receives ultrasonic waves;
A directivity adjustment unit for adjusting the directivity of the ultrasonic wave;
An ultrasonic sensor having a piezoelectric element disposed in the vibration part inside the main body part,
The ultrasonic sensor in which the directivity adjusting unit is provided on the vibration unit on the opposite side of the piezoelectric element.   The ultrasonic sensor according to claim 1, wherein the directivity adjusting unit is formed by providing a thickness to the vibrating unit.   The ultrasonic sensor according to claim 1, wherein the directivity adjusting unit is provided outside a region facing the piezoelectric element.   The ultrasonic sensor according to claim 1, wherein the main body has a cylindrical shape.

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