JP4532347B2 - Ultrasonic transducer - Google Patents

Description

  The present invention relates to an ultrasonic transducer that transmits and receives an ultrasonic frequency band.

In an ultrasonic transducer according to a conventional embodiment, when this is embedded in a car bumper or the like and an obstacle around it is detected, the pulse transducer electric signal is input to the ultrasonic transducer to generate an ultrasonic wave. An ultrasonic signal corresponding to the input pulse burst electric signal is oscillated from the sonic transducer, and the oscillated ultrasonic signal is reflected by the obstacle after reaching the obstacle, and part of the ultrasonic signal is the same Return to the ultrasonic transducer. The ultrasonic transducer detects an obstacle by receiving the reflected signal.
FIG. 2B is a schematic longitudinal sectional view of an ultrasonic transducer according to a conventional embodiment. FIG. 2A shows a schematic top view and a longitudinal sectional view of a bottomed cylindrical case in the ultrasonic transducer according to the conventional embodiment. Since the bottomed cylindrical case of the conventional embodiment obtains directivity that is wide in one direction and narrow in the other direction, as shown in FIG. It is hollowed out. In FIG. 2B, a piezoelectric element 1 is bonded to the inside of the bottom surface of the bottomed cylindrical case 2 made of an aluminum material or the like to form a unimorph vibrator. The input / output leads 5a are taken out from the surface opposite to the bonding surface of the piezoelectric element 1 with the bottomed cylindrical case 2, and the input / output leads 5b are taken out from the bottomed cylindrical case 2 by soldering or the like. The adhesive surface side of the piezoelectric element 1 with the bottomed cylindrical case 2 and the bottomed cylindrical case 2 are electrically connected. Further, the piezoelectric element 1, the input / output lead 5a, and the bottomed cylindrical case 2 The input / output lead 5b is electrically connected. The input / output leads 5a and 5b are soldered to the wires of the connector 6 with the PVC coated wire, respectively. A sound absorbing material 3 made of a silicone foam or the like is installed on the upper surface of the piezoelectric element 1, and a sealing agent 4 made of an elastic material such as a silicone material or a urethane material is filled in the bottomed cylindrical case 2 from above. It is configured.
Tanikoshi Shinji “Ultrasound and its usage-Ultrasonic transducers and ultrasonic motors” Nikkan Kogyo Shimbun 1994

  The problem to be solved is to further improve the directivity in a small ultrasonic transducer.

Although we have made intensive efforts to solve the above problems, we have been unable to find a clue to the solution. For example, as described above, even if the ratio of the distance between the long part and the short part of the side surface of the hollow part was increased, a sufficient effect was not obtained.
However, the present invention has achieved a sufficiently satisfactory effect. That is, in the ultrasonic transducer, among the center lines that pass through the center point of the bottom part, each of the four divided by the center line that passes through the shortest part of the opposite hollow part and the center line that is orthogonal thereto In this region, at least one or more digs are provided so as to further bite into the inner surface of the bottomed cylindrical case.

  The present invention has an advantage that it is possible to prevent erroneous detection due to the ground or the like in the case of detecting a longer distance than in the past by narrowing the directivity characteristics to be transmitted and received even in a small ultrasonic transducer. This also increases the frontal sensitivity and makes it possible to detect longer distances.

  When used in in-vehicle corner sensors, etc., it can be embedded in a bumper, etc., and stable obstacle detection from long distances to short distances can be realized with high reliability without malfunction.

FIG. 1B is a schematic longitudinal sectional view of an ultrasonic transducer according to an embodiment of the present invention. 1A shows a schematic top view and a longitudinal sectional view of a bottomed cylindrical case in an ultrasonic transducer according to an embodiment of the present invention. In FIG. 1-a, in the bottomed cylindrical case 2 which is made of an aluminum material and is hollowed relatively long in one direction and relatively short in another direction, a center line passing through a portion where the distance between the opposite hollow portions is the shortest, In addition, at least one or more of each region divided into four by the center line orthogonal thereto is dug so as to further bite into the inner surface of the bottomed cylindrical case. The input / output lead 5a from the piezoelectric element 1 and the opposite surface of the piezoelectric element 1 to the bottomed cylindrical case 2 and the adhesive surface side and the input / output lead 5b from the bottomed cylindrical case 2 are taken out by soldering or the like. The adhesive surface side of the piezoelectric element 1 with the bottomed cylindrical case 2 and the bottomed cylindrical case 2 are electrically connected. Further, the piezoelectric element 1, the input / output lead 5a, and the bottomed cylindrical case 2 are electrically connected. And the input / output lead 5b are electrically connected. A sound absorbing material 3 made of foamed silicone or the like is placed on the upper surface of the piezoelectric element 1, and a sealing agent 4 made of silicone material, urethane material or the like is filled into the bottomed cylindrical case 2 from above.
For example, at a transmission / reception frequency of 60 kHz, the vibration section of the ultrasonic transducer according to the conventional embodiment is as shown in FIG. As shown in FIG. 1-a, by providing a digging so as to bite into the inner surface of the bottomed cylindrical case, an elliptical vibration node spreads only in the major axis direction as shown in FIG. 3-b. As a result, in the conventional embodiment, as shown in FIG. 4-a, the object that was half-full angle 36 degrees in the vertical direction is dug so as to bite into the inner surface of the bottomed cylindrical case as shown in FIG. As shown in FIG. 4B, the half angle can be improved by 22 degrees and 10 degrees or more. Since the minor axis direction of the elliptical vibration node is equivalent to the conventional embodiment, the anisotropy of the directivity can be further increased. Also, the front sensitivity increases as shown in FIG.

  The present invention can be applied not only to a back sensor of a car but also to various fields where a drip-proof ultrasonic transducer is used.

a Schematic top view and longitudinal sectional view of a bottomed cylindrical case in an ultrasonic transducer according to an embodiment of the present invention b Schematic longitudinal sectional view of an ultrasonic transducer according to an embodiment of the present invention a Schematic top view and longitudinal sectional view of a bottomed cylindrical case in an ultrasonic transducer according to a conventional embodiment b Schematic longitudinal sectional view of an ultrasonic transducer according to a conventional embodiment a) Node of vibration of ultrasonic transducer according to the conventional embodiment b. Node of vibration of ultrasonic transducer according to the embodiment of the present invention a Directivity characteristics of an ultrasonic transducer according to a conventional embodiment b Directivity characteristics of an ultrasonic transducer according to an embodiment of the present invention Reflection sensitivity of the ultrasonic transducer according to the conventional embodiment and the ultrasonic transducer according to the embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Bottomed cylindrical case 3 Sound absorbing material 4 Sealant 5 a Input / output lead 5 b Input / output lead
6 Connector with PVC coated wire

Claims (1)

A piezoelectric element is bonded to the inside of the bottom of a bottomed cylindrical case that is relatively long in one direction and relatively short in the other direction to form a unimorph vibrator. In the ultrasonic transducer that performs transmission and reception, the center line that passes through the center point of the bottom is divided into four by the center line that passes through the shortest distance between the opposite hollow parts and the center line that is orthogonal to the center line. An ultrasonic transducer characterized in that at least one or more of each region is provided with a digging so as to further bite into the inner surface of the bottomed cylindrical case.

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