JPS5830362Y2 - electroacoustic transducer - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a waterproof structure for an electroacoustic transducer such as an ultrasonic transducer.

In recent years, ultrasonic switches have been widely used as non-contact door switches, etc., and the ultrasonic vibrator used as a transmitter or transfer device has conventionally had a structure as shown in FIG.

To be more specific, the cap 1 is made by squeezing an aluminum plate or the like into a cylindrical shape with a bottom, the lower edge 2 of which is slightly expanded outward, and the vibrator 3 made of a piezoelectric element inside the upper bottom surface. is attached.

The base 4, which is also made of an aluminum plate or the like, has a diameter slightly larger than the cap 1 in order to receive the lower edge 2, has a circular hole in the center, and has an outer peripheral edge and an inner hole. The peripheral edge portion is bent upward to form a wall portion, that is, the cross section is approximately U-shaped and doughnut-shaped.

A disc-shaped resin terminal block 5 is fitted into the circular hole and is bonded to the base 4 with an adhesive or the like. One of the terminals 6, 6 is connected to one electrode of the vibrator 3, and
The other end is connected to one end of the cap 1, and is electrically connected to the other electrode of the vibrator 3 through the cap 1.

Further, an elastic material 7 such as a sponge is laid in advance in the concave surface of the base 4 to prevent leakage of ultrasonic waves and vibration loss, and the cap 1 is placed on this elastic material 7. The lower edge portion 2 is bonded with an adhesive.

However, with this structure, when used in a bad atmosphere containing a large amount of water vapor or when water droplets are directly splashed on it, water leaks into the cap 1 from the elastic material 7 made of sponge or the like. This has the disadvantage that the oxidants penetrate into the oscillator 3, corrode the electrode portions of the vibrator 3, the terminals 6, 6, etc., and deteriorate the electrical performance.

On the other hand, tightly sealing this part prevents the vibrator 3 from freely vibrating, leading to a decrease in the output of the transmitter and a decrease in sensitivity in the receiver. There is a problem with that.

This idea was made in view of the above points, and in particular, by filling the area between the peripheral wall of the base and the edge of the cap with elastic adhesive resin, free vibration of the vibrator can be prevented. It is intended to seal the seal without
Next, an example thereof will be explained.

In FIG. 2, the outer peripheral wall 8 formed by bending the outer peripheral edge of the base 4 is formed slightly higher than that shown in FIG. elastic body 7
An outer peripheral wall 8 extends further upwards from the upper surface of the housing.

The extended outer peripheral wall 8 allows the cap 1 to
The gap formed between the bottom edge 2 and the bottom edge 2 is filled with elastic adhesive resin 9 without any gaps.

The adhesive resin 9 is initially fluid and still has elasticity even after hardening, and suitable materials include, for example, rubber-based adhesives or two-component curing silicone rubber.

Further, the cap 1 and the upper surface of the elastic material 7 may be bonded in advance as in the conventional manner, but by using adhesive resin 9 having an appropriate strength, this work can be omitted and the top surface of the vibrator 3 can be bonded. Needless to say, this is preferable in terms of sensitivity reduction.

As is clear from the above description, the electroacoustic transducer according to this invention has a structure in which there is a gap between the peripheral wall of the base and the edge of the cap.
Since it is filled with an elastic adhesive resin, it covers the elastic material made of sponge etc. that was previously exposed to the outside, and also completely seals between the cap and the base to ensure waterproof performance. It has the advantage that the seal does not adversely affect the characteristics of the vibrator, such as a decrease in sensitivity.

[Brief explanation of drawings]

FIG. 1 is a half-sectional view showing the structure of a conventional ultrasonic vibrator, and FIG. 2 is a half-sectional view showing the structure of ultrasonic vibration according to this invention. 1... Cap, 3... Vibrator, 4.
...Base, 5...Terminal block, 6...
- Terminal, 7...Elastic material, 8...Outer peripheral wall, 9...Adhesive resin.

Claims (1)

[Scope of utility model registration request] A bottomed cylindrical cap with a vibrator attached to the inside of the bottom,
It has an outer diameter that is one size larger than the diameter of the cap, and closes the opening surface of the cap, and a terminal that is electrically connected to the vibrator is provided upright in the center of the cap, and the outer peripheral edge is newly curved. It consists of a base with a concave cross section that forms a peripheral wall, and an elastic material that is laid within the concave surface of this base and interposed between the cap and the base, and in particular, the peripheral wall of the base and the cap. An electroacoustic transducer filled with elastic adhesive resin between the edges.