JPS5830384Y2 - Ultrasonic electroacoustic transducer - Google Patents

Description

[Detailed description of the invention] The present invention relates to an ultrasonic electroacoustic transducer using a piezoelectric ceramic vibrator, and more specifically, to an ultrasonic electroacoustic transducer that is suitable for applied equipment used outdoors and under adverse conditions. It is.

Conventionally, in this type of ultrasonic electroacoustic transducer, as shown in FIG. 1, a piezoelectric ceramic vibrator 2 is attached to the inner bottom surface of a case 1 made of aluminum, and the open part of the case 1 is closed with a terminal plate 3. It had a drip-proof structure sealed by molding with an elastic adhesive 4 or resin.

Note that 5 and 6 are lead terminals implanted in the terminal plate 3, to which lead wires connected to respective electrodes of the piezoelectric ceramic vibrator 2 are connected.

Further, 7 is a metal plate, which is used to shield the piezoelectric ceramic vibrator 2 from the outside together with the case 1.

However, in the case of the conventional structure, it is designed with the purpose of sealing and not providing vibration damping, so due to the structure, Case 1
The thickness of the side part must be thicker than the thickness of the bottom of the case 1 to which the piezoelectric ceramic vibrator 2 is attached, which increases the size and also makes it difficult to attach the piezoelectric ceramic vibrator 2 to a flat diaphragm. Compared to the conventional case, the vibration is affected by the side parts and is lowered, resulting in a lower sensitivity.

The present invention has been developed in view of these conventional drawbacks, and will be described below with reference to FIGS. 2 and 3 showing one embodiment of the present invention.

In the figure, 10 is an inner case with a U-shaped cross section with one end open and the other end closed, and 11 is an outer case with a U-shaped cross section with one end open and the other end closed into which the inner case 10 is inserted. ,
These inner case 10 and outer case 11 are made of a metal material such as aluminum.

Further, the inner case 10 and the outer case 11 may have a truncated pyramid shape or a truncated cone shape inclined inwardly or outwardly.

A piezoelectric ceramic vibrator 12 is attached to the outer bottom surface of the inner case 10 with solder or resin adhesive, thereby forming a bimorph vibrating section 13.

Further, a conical resonator 14 is disposed within the inner case 10 so that its tip is fixed approximately at the center of the bimorph vibrating section 13.

The inner case 10 to which the piezoelectric ceramic vibrator 12 and the conical resonator 14 are attached may be inserted into the outer case 11 with the piezoelectric ceramic vibrator 12 side facing inside and supported with an adhesive, or It is fixed by mechanically pressurizing a part of the side surface of the outer case 11 inward.

Further, the piezoelectric ceramic vibrator 12 is provided at the bottom of the outer case 11.
A through hole 17 for drawing out the lead wire 15 connected to the electrode of
is provided.

The other lead wire 16 is connected to the outer case 11, and thereby to the other electrode of the piezoelectric ceramic vibrator 12.

Here, the conical resonator 14 resonates in response to the vibration of the bimorph vibrating section 13 and amplifies the vibration, and the acoustic resistivity of the conical resonator 14 is smaller than the acoustic resistivity of the bimorph vibrating section 13. Since it approximates the specific resistance of air and results in a wide vibration area, it is possible to obtain sensitivity-frequency characteristics having filter characteristics as shown in FIG.

Note that the characteristic a in FIG. 3 is the characteristic of the ultrasonic electroacoustic transducer according to the present invention, or the characteristic of the conventional ultrasonic electroacoustic transducer.

As described above, according to the ultrasonic electroacoustic transducer of the present invention, a piezoelectric ceramic vibrator is attached to the outer bottom surface of the inner case, and the inner case is further inserted into the outer case to house the piezoelectric ceramic vibrator. Because of its structure, it has excellent drip-proof and dust-proof effects, and because it has a conical resonator, it resonates with the vibrations of the bimorph vibrating section, which improves acoustic conversion efficiency and provides ultra-high sensitivity filter characteristics. A sonic electroacoustic transducer can be obtained.

Furthermore, it is possible to attach the bimorph vibrating part, that is, attach the inner case to the outer case and attach the conical resonator at the same time using soldering. It has the advantage that it can be assembled and used at a certain high temperature.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a conventional ultrasonic electroacoustic transducer, Fig. 2 is a cross-sectional view showing an ultrasonic electroacoustic transducer according to an embodiment of the present invention, and Fig. 3 is a cross-sectional view showing a conventional ultrasonic electroacoustic transducer. FIG. 3 is a diagram showing a comparison of sensitivity-frequency characteristics. 10... Inner case, 11... Outer case, 12... Piezoelectric ceramic vibrator, 13...
Bimorph vibrating section, 14... Conical resonator.

Claims (1)

[Scope of utility model registration request] It has an outer case and an inner case each having a U-shaped cross section with one end open and the other end closed, and a piezoelectric ceramic vibrator is attached to the outer bottom surface of the inner case to constitute a bimorph vibrating section. A conical resonator is disposed within the inner case so that the tip of the bimorph vibrating section is attached to the central part, and the inner case is placed within the outer case with the piezoelectric ceramic vibrator side facing inside. An ultrasonic electroacoustic transducer that is inserted.