JP2013143589A - Ultrasonic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of an ultrasonic transducer using a conventional resin cap that there is a possibility that rising or a displacement of a resin cap occurs when assembling the resin cap, and directional characteristics are affected.SOLUTION: By insert-molding a metal pin in a bottomed cylindrical case composed of a composite formed by blending a large amount of silica in an epoxy resin, it is possible to connect to a drive circuit without using a resin-made cap which is conventionally required.

Description

  The present invention relates to an aerial ultrasonic transducer that transmits or receives ultrasonic waves.

Today, object detection systems using ultrasonic transceivers are used in various fields. Particularly, mass-produced ultrasonic transmitters / receivers for object detection on the rear or side of a vehicle are produced.

This ultrasonic transmitter / receiver generally has a basic structure including a bottomed cylindrical case made of an aluminum alloy, a piezoelectric element attached to the bottom surface of the case, and electrode wires attached to both surfaces of the piezoelectric element. By applying voltage to the double-sided electrodes of the piezoelectric element, ultrasonic waves are generated from the design surface of the case. In addition, the ultrasonic wave reflected by the object can be received on the case design surface. It is possible to detect the distance to the object by measuring the time until this reflection.

FIG. 3 is a schematic longitudinal sectional view of an ultrasonic transducer according to a conventional embodiment. In FIG. 3, the piezoelectric element 1 is bonded inside the bottom surface of the bottomed cylindrical case 2 made of an aluminum material or the like to constitute a unimorph vibrator. At this time, the adhesive surface of the piezoelectric element and the bottomed cylindrical case are electrically connected and have the same potential. The input / output lead 5 a is soldered to the bonded piezoelectric element 1, and the input / output lead 5 b is soldered inside the side surface of the bottomed cylindrical case 2. The input / output leads 5a and 5b are soldered to metal terminals attached to a resin cap. A sound absorbing material 3 made of 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 silicone material or urethane material is filled into the bottomed cylindrical case 2 from above. Has been.

This ultrasonic transducer has a specific horizontal directivity and vertical directivity depending on the shape of the case, and the case shape is designed according to the location to be mounted on the vehicle and the distance to be detected.

When an obstacle outside the vehicle is detected, it is desirable that the ground is not detected as an obstacle and that the horizontal detection area is wide. For this reason, the conventional bottomed cylindrical case has an elliptical opening that is long in the vertical direction, and the horizontal width is narrow. By using such a case, the directivity of the ultrasonic sensor is narrow in the vertical direction and wide in the horizontal direction.

Since the assembly of the resin cap in FIG. 3 affects the directivity, the assembly of the resin cap needs to be performed accurately.

In a structure using a resin cap, after attaching the resin cap to the bottomed cylindrical case, the input / output lead is generally wound and the input / output lead is soldered to the metal pin of the resin cap. Depending on how the lead wires are wound, there is concern about disconnection due to thermal stress. Therefore, it is necessary to wind the input / output leads in a predetermined state.

Japanese Patent Laid-Open No. 10-332817 JP 2009-192252 A

In an ultrasonic transmitter / receiver using a conventional bottomed cylindrical case made of an aluminum alloy and a resin cap, there is a possibility that the resin cap may float or shift when the resin cap is assembled. When the resin cap is assembled with a displacement, directivity is affected. If the directivity is affected, malfunction may occur when an obstacle is detected.

In addition, the presence of the resin cap increases the number of parts, and there is a problem that the manufacturing cost is unlikely to decrease.

In addition, since there is a resin cap, there is a problem that it is difficult to crawl the input / output leads in a predetermined state and solder them to the metal pins.

A step was provided on the side surface of the bottomed cylindrical case, and two insert-molded metal pins extending from the step toward the opening were provided on the bottomed cylindrical case.

The positional deviation of the resin cap in the assembly process was reduced.
It became possible to stabilize the directivity of the ultrasonic transceiver.

By insert-molding the electrode pin into the bottomed cylindrical case made of an insulating material, the resin cap assembly process is not necessary. For this reason, process defects in the assembly process of the resin cap could be reduced. More stable production can be performed.

The number of processes and the number of parts are reduced, and the production cost is reduced.

Since there is no resin cap that obstructs the work, the input / output leads can be easily turned.

By causing the metal terminal to extend inside the bottomed cylindrical case, the stress generated in the input / output leads was alleviated. In addition, a state where the stress generated in the input / output seeds is small was easily realized.

Schematic longitudinal sectional view of a case according to an embodiment of the present invention 1 is a schematic longitudinal sectional view of an ultrasonic transducer according to an embodiment of the present invention. Schematic longitudinal sectional view of an ultrasonic transducer according to a conventional embodiment

FIG. 1 shows a schematic view (a perspective view and a sectional view) of a bottomed cylindrical case according to the present invention. The bottomed cylindrical case 2 made of an insulator has an outer diameter of 14.0 mm and a height of 9.0 mm. The bottomed cylindrical case is made of an insulating composite material based on an epoxy resin and filled with a large amount of silica (90% or more).
The bottom surface of the bottomed cylindrical case 2 is, for example, a flat ellipse having a major axis side of 12.0 mm and a minor axis side of 5.0 mm. The bottomed cylindrical case 2 has a semicircular step on the opening side. The step is provided at a position 5 mm from the top surface of the bottomed cylindrical case 2. The step is provided on the side surface on the thick side of the bottomed cylindrical case. It is a semicircle with a radius of 2.0 mm from the edge of the side surface.
Two metal pins are insert-molded in the step portion. One end of the metal pin extends vertically from the step toward the opening of the bottomed cylindrical case. The other end extends from the inner side surface of the bottomed cylindrical case 2 toward the inner side of the bottomed cylindrical case.

By providing the slide unit in the molding die of the bottomed cylindrical case 2, the metal pin 8 can be molded into a shape protruding from the side surface of the bottomed cylindrical case 2.

FIG. 2 shows a schematic structural diagram of an ultrasonic transducer according to the embodiment of the present invention. In the figure, only the bottomed cylindrical case 2, the metal pins 8 provided in the bottomed cylindrical case, the input / output leads 5 a (5 b), and the piezoelectric element 1 are illustrated. The sound absorbing material 3 inside the bottomed cylindrical case and the sealant 4 made of silicone are omitted.

A piezoelectric element 1 provided with a folded electrode is bonded to the bottom surface of the bottomed cylindrical case 2.
The GND side silver electrode and the input / output lead 5a of the piezoelectric element 1 and the + side silver electrode and the input / output lead 5b are soldered. The input / output leads 5a are soldered in parallel to the electrode pins 8 protruding from the side surface of the bottomed cylindrical case 2. The other input / output lead 5b is soldered in parallel to the metal pin. A sound absorbing material 3 made of silicone foam material or the like is placed on the upper surface of the piezoelectric element 1, and a sealant 4 made of silicone material is filled into the bottomed cylindrical case 2 inside the bottomed cylindrical case 2. .
The soldered portions of the metal pins 8 and the input / output leads 5a (5b) are completely covered with the sealant 4 made of a cured silicone material.

Since the material of the bottomed cylindrical case 2 is an insulator, even if both the GND side and the + side metal pins 8 are insert-molded, it is possible to ensure insulation on the GND side and the + side.

The work of winding the input / output lead wires from the opening side of the bottomed cylindrical case and soldering them to the metal pins can be facilitated.

The metal pin 8 is exposed inward from the inner side surface of the bottomed cylindrical case, and the input / output leads are soldered in parallel to the exposed metal terminal, thereby reducing the stress generated by the thermal expansion / contraction stress of the member. The state can be easily realized.

  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. In addition, even when a case with a shape having no partial directivity is produced, it is possible to provide arbitrary directivity characteristics.

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Bottomed cylindrical case 3 Sound-absorbing material 4 Sealant 5a Input / output lead 5b Input / output lead
6 Spacer 7 Resin cap with metal terminal 8 Electrode pin 9a Electrode 1 made of silver or the like
9b Electrode 2 made of silver or the like
10 Wire harness

Claims (2)

A bottomed cylindrical case made of insulating resin;
A piezoelectric element bonded to the bottom of the bottomed cylindrical case;
Two electrode pins provided on the side surface of the bottomed cylindrical case,
An input / output lead for electrically connecting the piezoelectric element and the electrode pin;
Silicone filled up to the opening of the bottomed cylindrical case or near the opening;
In the ultrasonic transducer for transmitting and receiving ultrasonic waves by the vibration of the unimorph vibrator by forming the unimorph vibrator by laminating the piezoelectric element inside the bottom surface of the bottomed cylindrical case,

The bottomed cylindrical case has a step on at least one inner side surface so that the area of the opening is wider than the bottom surface,
An ultrasonic transducer according to claim 1, wherein the two metal pins are integrally formed by insert molding so that one end of the two metal pins is exposed and extended from the step on one side of the bottomed cylindrical case to the opening side. Insulating resin constituting the bottomed cylindrical case,
2. The ultrasonic transducer according to claim 1, wherein the ultrasonic transducer is a resin material based on an epoxy resin.

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