JPH09284896A - Ultrasonic wave transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic wave transmitter-receiver configured to be easily reserved for required directivity even without using an ultrasonic wave horn. SOLUTION: This transmitter-receiver 11 is provided with a case 13 whose one side is open and having a hollow 12 and a bottom size and with a piezoelectric vibrator 2 contained in the hollow 12 of the case 13 and arranged on the bottom. In this case, the cross sectional view of the hollow 12 of the case 13 is rectangular or ellipse, and the thickness T1 of the side face of the case 13 is made thicker than the thickness T2 of the bottom side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic wave transmitter / receiver used as an obstacle detection sensor mounted on an automobile.

[0002]

2. Description of the Related Art As an ultrasonic wave transmitter / receiver 1 of this type, as shown in FIG. 4, a piezoelectric vibrating element 2 in the shape of a flat plate having electrodes (not shown) formed on opposing main surfaces, and a hollow A one-sided open case body 4 made of metal, in which one main surface of the piezoelectric vibration element 2 is fixed on the bottom surface of the portion 3, and a connector cable 5
It is known that it is provided with and. The hollow portion 3 and the case body 4 here are both circular in cross-sectional view, and are separated and led out from the connector cable 5 introduced into the hollow portion 3 of the case body 4. Each of the signal lines 5a and 5b is connected to the inner side surface of the case body 4 to which one side main surface of the piezoelectric vibrating element 2 is fixed and is conductive, and the other side main surface of the piezoelectric vibrating element 2. .

Reference numeral 6 in the drawing is a sound absorbing material such as felt, and 7 is an insulating resin having elasticity such as silicon rubber or urethane rubber. The sound absorbing material 6 at this time is placed so as to cover the other principal surface of the piezoelectric vibrating element 2, while the insulating resin 7 is filled in the hollow portion 3 and then the piezoelectric vibrating element 2 and the sound absorbing material are filled. 6 is hermetically sealed.

By the way, the ultrasonic wave transmitter / receiver 1 is mounted on a bumper (not shown) of an automobile and used as an obstacle detection sensor such as a back sonar or a corner sensor. At the time of attachment to the bumper, positioning is performed so that the bottom surface of the hollow portion 3 to which the one-side main surface of the piezoelectric vibrating element 2 is fixed is aligned with the direction parallel to the road surface, and then arranged. In this case, on the outer surface of the case body 4, it is necessary to secure directional characteristics such that the ultrasonic wave transmitting / receiving range in the horizontal direction is wide and the ultrasonic wave transmitting / receiving range in the vertical direction is narrowed. The ultrasonic wave which is the outer surface facing the ultrasonic wave transmitting / receiving surface 4a of the case body 4, that is, the bottom surface of the hollow portion 3 to which the piezoelectric vibrating element 2 is fixed by the ultrasonic horn 8 which is externally fitted to the ultrasonic wave. The structure surrounding the wave transmitting / receiving surface 4a is adopted.

That is, in the ultrasonic wave transmitter / receiver 1 according to this conventional embodiment, a blind spot occurs when the ultrasonic wave transmission / reception range in the horizontal direction is too narrow, and when the ultrasonic wave transmission / reception range in the vertical direction is too wide. Since the reflected wave from the ground becomes noise, the ultrasonic wave transmission / reception range of the ultrasonic wave is controlled by the ultrasonic horn 8 to control the directional characteristics of the ultrasonic wave transmitter / receiver 1.

[0006]

However, in the conventional ultrasonic wave transmitter / receiver 1, the ultrasonic wave transmitter / receiver surface 4a of the case body 4 is surrounded by the ultrasonic wave horn 8. Rainwater, earth and sand, dust, and the like may be accumulated and clogged between the body 4 and the ultrasonic horn 8, resulting in a malfunction of the ultrasonic transducer 1. In addition, not only the temperature effect due to the installation of the ultrasonic horn 8 may occur in the ultrasonic transducer 1, but also the ultrasonic horn 8 projects from the outer surface of the bumper, so that the appearance is uniform. It was supposed to be damaged. In addition, the ultrasonic horn 8 for the case body 4
The directional characteristics are likely to be affected by the mounting position of, and the inconvenience of requiring a troublesome work for securing the mounting accuracy has occurred.

The present invention was devised in view of these inconveniences, and it is an object of the present invention to provide an ultrasonic wave transmitter / receiver having a structure capable of easily ensuring a necessary directional characteristic without using an ultrasonic horn. Has an aim.

[0008]

An ultrasonic transducer according to the present invention is a case body having a hollow portion and a bottom surface and having an opening on one side, and is housed in the hollow portion of the case body and arranged on the bottom surface. A piezoelectric vibrating element, wherein the hollow part of the case body has a rectangular or oval cross-sectional shape, and the side surface thickness of the case body is formed to be thicker than its bottom surface thickness. It is characterized by being.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a simplified configuration of an ultrasonic wave transmitter / receiver according to the present embodiment, and FIG. 2 is a line A- in FIG.
FIG. 3 is a horizontal cross-sectional view of the ultrasonic wave transmitter / receiver taken along the line A, and FIG. 3 is a vertical cross-sectional view showing a simplified configuration of the ultrasonic wave transmitter / receiver according to the modification. It is a vessel. In FIGS. 1 and 2, the same parts and portions as those of FIG. 3 showing the ultrasonic transmitter / receiver 1 according to the related art are designated by the same reference numerals.

Ultrasonic wave transmitter / receiver 11 according to the present embodiment
As shown in FIGS. 1 and 2, the piezoelectric vibrating element 2 has a circular flat plate shape in which electrodes (not shown) are formed on the main surfaces facing each other, and the cross-sectional view has a substantially square shape. The case body 13 is provided with a case body 13 in which a hollow portion 12 for accommodating the piezoelectric vibrating element 2 is formed, and a connector cable 5 for signal input / output.
Is made of light and highly elastic metal such as aluminum. Of course, the case body 13 may not be made of metal but may be a resin molded product or the like, and the case body 13 itself may have a circular cross-sectional view shape.

At this time, the hollow portion 12 of the case body 13 has a rectangular or oval cross-sectional shape (in FIG. 2, it is rectangular), and the side face thickness T1 thereof is the bottom face thickness. Thicker than T2 (T1> T
2), and one main surface of the piezoelectric vibrating element 2 is fixed to the center position on the bottom surface thereof by using an adhesive (not shown). Further, the connector cable 5 is introduced into the hollow portion 12, and the signal line 5 separated from the connector cable 5 and led out.
Each of a and 5b is connected to the inner side surface of the case body 13 to which one side main surface of the piezoelectric vibrating element 2 is fixed and conducts, and the other side main surface of the piezoelectric vibrating element 2. Further, a sound absorbing material 6 made of felt or the like is placed on the other main surface of the piezoelectric vibrating element 2 fixed to the bottom surface of the case body 13, and the piezoelectric vibrating element 2 and the sound absorbing material 6 are hollow portions 12. It is hermetically sealed with an insulative resin 7 such as silicon rubber filled therein.

Furthermore, the ultrasonic wave transmitter / receiver 11 having such a structure is attached to a bumper (not shown) of an automobile, and is used for detecting obstacles such as a back sonar and a corner sensor. It will be used as a sensor. The ultrasonic wave transmitter / receiver 11 is configured such that the bottom surface of the case body 13 to which one side main surface of the piezoelectric vibrating element 2 is fixed, that is, the ultrasonic wave transmitter / receiver surface 13a of the case body 13 is parallel to the road surface or the like. The positioning and adjustment are performed and then the mounting is performed, and the long axis direction of the hollow portion 12 at the time of mounting is disposed along the horizontal direction.

Therefore, the inventor of the present invention has made the cross-sectional dimension of the case body 13 constituting the ultrasonic wave transmitter / receiver 11 18 mm.
× 18 mm, its total length is 10 mm, the cross-sectional dimension of the hollow portion 12 is 16 mm × 8 mm, and its side surface thickness T1 is 1 mm,
The directional characteristics were examined with the bottom surface thickness T2 set to 0.7 mm, the outer diameter of the piezoelectric vibration element 2 set to 10 mm, and the thickness set to 0.15 mm. That is, in this investigation, the case body 1 that constitutes the ultrasonic wave transmitter / receiver 11
By applying an AC voltage equal to the natural frequency of 3 to the piezoelectric vibrating element 2, the ultrasonic wave is transmitted from the ultrasonic wave transmitting / receiving surface 13a of the case body 13, and then the case body 13 is moved by the ultrasonic wave reflected from the object. After resonating, the voltage is extracted.

As a result of conducting a survey under such conditions, the following survey results were obtained.
That is, at this time, the ultrasonic wave transmitting / receiving surface 13a of the case body 13 facing the bottom surface of the case body 13 is 40 KH.
A vibration mode that vibrates at a large resonance peak with z, is long in the major axis direction of the hollow portion 12 and has an elliptical shape that is short in the minor axis direction, and as a result, ultrasonic waves in the horizontal direction are obtained. It has been clarified that the directional characteristics can be ensured such that the transmission and reception range of the ultrasonic wave is wide and the transmission and reception range of the ultrasonic wave in the vertical direction is narrowed. It is considered that the reason why such a vibration mode is obtained is that unnecessary vibrations are less likely to occur at the time of receiving a wave, and vibration leakage to the case body 13 is reduced.

By the way, on the outer surface of the case body 13 constituting the ultrasonic wave transmitter / receiver 11 according to the present embodiment, a groove portion having a predetermined depth is formed so as to coincide with the major axis direction of the hollow portion 12. Although the groove 14 is provided, if such a groove 14 is provided, not only the elastic wave generated in the case body 13 can be attenuated to suppress unnecessary vibration, but also ultrasonic wave transmission / reception is performed. There is an advantage that the mounting direction of the wave filter 11 can be easily confirmed. In the present embodiment,
Although the shape of the hollow portion 12 formed in the case body 13 is rectangular in cross-sectional view, the present inventor has confirmed that the shape is not limited to such a shape and may be an elliptical shape. .

Furthermore, in the ultrasonic wave transmitter / receiver 11 according to the present embodiment, as shown in FIG. 1, the ultrasonic wave transmitter / receiver 11 is separated from the connector cable 5 introduced into the hollow portion 12 of the case body 13 and led out. Although each of the signal lines 5a and 5b is connected to the inner side surface of the case body 13 and the other main surface of the piezoelectric vibrating element 2, as shown in the modification of FIG. Capacitor 15 for temperature compensation between 5b
It is also possible to intervene. When such a configuration is adopted, the temperature compensating capacitor 15
Since it is integrally provided in the case body 13, the temperature followability becomes extremely good, and there is an advantage that the temperature drift of the ultrasonic wave transmitter / receiver 11 can be easily reduced. The capacitor 15 has a negative (-) temperature coefficient, and the positive (+) of the electrostatic capacity of the piezoelectric vibrating element 2.
It is used to cancel the temperature coefficient of.

[0018]

As described above, according to the ultrasonic transmitter / receiver of the present invention, the ultrasonic wave transmitting / receiving range in the horizontal direction is wide and the ultrasonic wave transmitting / receiving range in the vertical direction is narrow. Since it is possible to easily secure the directional characteristic, it is not necessary to secure the directional characteristic after using the ultrasonic horn, and the inconvenience associated with the use of the ultrasonic horn does not occur.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a simplified configuration of an ultrasonic wave transmitter / receiver according to an embodiment.

FIG. 2 is a cross-sectional view of the ultrasonic wave transmitter / receiver taken along the line AA in FIG.

FIG. 3 is a vertical sectional view showing a simplified configuration of an ultrasonic wave transmitter / receiver according to a modification.

FIG. 4 is a longitudinal sectional view showing a simplified configuration of an ultrasonic wave transmitter / receiver according to a conventional form.

[Explanation of symbols]

 2 Piezoelectric vibration element 11 Ultrasonic wave transmitter / receiver 12 Hollow part 13 Case body T1 Side surface thickness of hollow part T2 Bottom surface thickness of hollow part

Claims (1)

[Claims] 1. An ultrasonic transducer having a case body having a hollow portion and a bottom surface and having an opening on one side, and a piezoelectric vibration element housed in the hollow portion of the case body and arranged on the bottom surface. The hollow portion of the case body has a rectangular or oval cross-sectional shape, and the side wall thickness of the case body is formed to be thicker than the bottom surface thickness thereof. .