JP2015035749A - Ultrasonic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic transducer which achieves downsizing and low costs.SOLUTION: A housing of an ultrasonic transducer includes: a metal case 1b having a cup shape; and a resin support part 2 having a cup shape. An inner surface of the case 1b and a part at the opening side in the support part are adhered to each other to form the housing with no opening part.

Description

The present invention relates to an aerial ultrasonic transducer that can be reduced in size and cost while maintaining good acoustic characteristics.

In ultrasonic transducers used for detecting obstacles in automobiles, the use of drip-proof ultrasonic sensors that can be used outdoors is increasing.
In this drip-proof ultrasonic transducer, a unimorph vibrator is configured by bonding a piezoelectric element to the inside of the bottom of a bottomed cylindrical metal casing made of an aluminum alloy or the like.
In recent years, the cylindrical portion of the metal casing and the plate-like bottom portion that becomes the vibration surface by bonding the piezoelectric element are made independent, thereby reducing processing and assembly costs, and further, the cylindrical portion and the bottom portion. Improvement of functionality such as conductivity and strength has been studied by using different materials.

FIG. 1 shows a structure of an ultrasonic transducer having a general bottomed cylindrical casing. In a casing in which a diaphragm made of an aluminum alloy is bonded to a cylindrical support made of resin with an adhesive, a piezoelectric element 7 provided with a folded electrode is bonded to the bottom of the casing. A lead wire 5 is soldered to the + side electrode 7 a and the GND side electrode 7 b of the piezoelectric element 7. One end of the lead wire 5 is soldered to the + side and the GND side of the external input / output terminal 6. The piezoelectric element 7 is covered with a sound absorbing material 3 made of silicone foam. The inside of the bottomed cylindrical case 2 is filled with a sealant 4 such as silicone having a Shore A hardness of 30 to 60.

JP-A-11-266497 JP2000-23289

In conventional ultrasonic transmitters and receivers with a bottomed cylindrical casing, a sound absorbing material made of a porous material is installed on the bottom of the casing to reduce reverberation, and moisture flows into the casing to deteriorate components. In order to prevent this, the inside is filled with a sealing material such as silicone resin or urethane resin. In order to arrange the sound absorbing material and the sealing material inside the casing, the cylindrical portion of the casing needs to have a certain height or more, and it is difficult to reduce the size by reducing the height of the casing. Yes.

Furthermore, since the cylindrical portion of the housing is made of a resin having rigidity lower than that of metal, vibration energy is easily consumed by unnecessary vibration around the opening, and there is a problem that sensitivity is lowered and reverberation is increased.

In the first and second aspects of the invention, since the casing has a sealed structure having no opening, unnecessary vibration is less likely to occur even if the support portion is made of resin, so that the sensitivity is eliminated without using a sound absorbing material. Drop and reverberation elongation are suppressed, and it becomes possible to improve waterproofness without a sealing material.
Therefore, the sound absorbing material and the sealing material are unnecessary from the inside of the housing, and the cost can be reduced by downsizing the ultrasonic transducer and reducing the number of members.

In the invention according to claim 3, the number of parts can be reduced by providing the external input / output terminal on the support portion of the casing.

In the invention according to claim 4, by providing an elastic body having an effect of absorbing vibration of the casing between the casing and the resin member having the input / output terminal made of metal, the ultrasonic transducer is provided. The noise signal generated in the housing due to vibration during driving is reduced by the vibration absorber, and the influence of the noise signal on the output signal can be suppressed.

As described above, since the ultrasonic transducer according to the present invention can reduce the number of components while maintaining good acoustic characteristics, a small and low-cost ultrasonic transducer can be provided.

Schematic cross-sectional view and top view of a conventional ultrasonic transducer, and layout of elements in the housing Schematic sectional view and top view of an ultrasonic transducer according to an embodiment of the present invention Schematic sectional view and top view of an ultrasonic transducer according to an embodiment of the present invention Schematic sectional view and top view of an ultrasonic transducer according to an embodiment of the present invention Schematic sectional view and top view of an ultrasonic transducer according to an embodiment of the present invention Schematic sectional view and top view of an ultrasonic transducer according to an embodiment of the present invention

FIG. 2 shows a schematic cross-sectional view and a top view of the ultrasonic transducer according to the embodiment of the present invention.
The diaphragm 1a is formed by molding an aluminum alloy. A piezoelectric element 7 having a folded electrode is bonded to the bottom surface of the diaphragm 1a. The support portion 2 is formed by molding an epoxy resin, and an input / output terminal 6 is provided on the upper surface. The input / output terminal 6 and the electrode of the piezoelectric element 7 are electrically connected by soldering the lead wire 5. The lead wire 5 is led out of the housing through a lead lead-out portion 10 provided on the support portion side in the vicinity of the bonding surface between the support portion 2 and the diaphragm 1b. The lead lead portion 10 is sealed with an adhesive made of an epoxy resin after the lead wire 5 is drawn out of the housing.
Here, the material of the diaphragm 1a is not limited to an aluminum alloy, and other metals such as stainless steel may be used. The material of the cylindrical case 2 is not limited to the epoxy resin, and other resins such as PBT may be used. The shape of the input / output terminal 6 connected to the outside may be other than the pin terminal. For example, a structure using a wire harness as a terminal, a structure in which the lead wire 5 is directly connected to a circuit, or the like can be considered. The lead wire 5 may be a flexible conductor, and for example, a flexible substrate may be used. The material of the adhesive is not limited to the epoxy resin, and other resins such as silicon resin and urethane resin may be used as long as the waterproofness of the housing is maintained.

FIG. 3 shows a schematic cross-sectional view and a top view of the ultrasonic transducer according to the embodiment of the present invention.
The ultrasonic transducer shown in FIG. 3 replaces the diaphragm 1a with the bottomed cylindrical case 1b in the ultrasonic transducer shown in the first embodiment, and the lead portion 5 of the lead wire 5 is a side surface of the support portion 2. It consists of the structure provided in.
Here, the material of the bottomed cylindrical case 1b is not limited to the aluminum alloy, and other metals such as stainless steel may be used.

FIG. 4 shows a schematic cross-sectional view and a top view of the ultrasonic transducer according to the embodiment of the present invention.
The ultrasonic transducer shown in FIG. 4 has a structure in which the input / output terminal 6 extends to the inside of the housing and is connected to the lead wire 5 inside the housing in the ultrasonic transducer shown in the second embodiment.

FIG. 5 shows a schematic cross-sectional view and a top view of the ultrasonic transducer according to the embodiment of the present invention.
The ultrasonic transducer shown in FIG. 5 is the same as the ultrasonic transducer shown in Embodiment 2, but the shape of the support portion 2 is changed from a circular shape to an elliptical shape, and the inner shape of the bottomed cylindrical case 1b is also the support portion 2. It has a structure with a shape corresponding to the outer shape.

FIG. 6 shows a schematic cross-sectional view and a top view of the ultrasonic transducer according to the embodiment of the present invention.
The ultrasonic transducer shown in FIG. 6 has a structure in which a vibration absorber 8 is provided between the input / output terminal 6 and the support portion 2 in the ultrasonic transducer shown in the fourth embodiment. The input / output terminal is provided with a resin member such as PBT for support. The vibration absorber 8 is a material that can satisfy the relationship of the amplitude of the casing> the amplitude of the input / output terminals when driven in the temperature range of −40 ° C. to 90 ° C., for example, silicone rubber An elastic body such as is used.

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

DESCRIPTION OF SYMBOLS 1a Diaphragm 1b Bottomed cylindrical case 2 Support part 3 Sound-absorbing material 4 Sealant 5 Lead wire 6 Input / output terminal 7 Piezoelectric element having a folded electrode 7a GND side electrode 7b + side electrode 8 Vibration absorber 9 Resin member 10 Lead Drawer

Claims (4)

A bottomed cylindrical case made of metal in which a piezoelectric element is arranged on the bottom of the inner surface;
Having a casing made of a bottomed cylindrical support made of a separate resin;
A part of the inner surface of the case and a part on the opening side of the support part are bonded so that no opening is formed in the casing.
A diaphragm made of metal on which a piezoelectric element is disposed;
Having a casing made of a bottomed cylindrical support made of a separate resin;
A part of the inner surface of the case and a part on the opening side of the support part are bonded so that no opening is formed in the casing.
3. The ultrasonic transducer according to claim 1, wherein an external input / output terminal is provided at one end where the case or the diaphragm is not bonded. Here, the external input terminal may penetrate the support portion and reach the inside of the housing.
In the said support part of Claims 1-2, the vibration absorber was provided between the resin member which has the input / output terminal which consists of an input / output terminal which the said case or the said diaphragm is not adhere | attached, and metal. Features an ultrasonic transducer.

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