JPS5915192Y2 - electroacoustic transducer - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an ultrasonic electroacoustic transducer used in a remote control device for a television receiver, a remote control device for toys, various proximity switches, and the like.

A conventional electroacoustic transducer is a bimorph vibrator 3 made by laminating two piezoelectric ceramic vibrators 1 and 2 as shown in FIG.
A conical resonator 4 is attached to the center of one surface, and the other surface of the bimorph resonator 3 is attached to the resonator support portion 6a of two stacked terminal plates 6, 7 via an elastic adhesive 5. It is housed and fixed in a case 9 with a screen 8 attached to one opening from the other opening.

In this case, the case 9 consists of a cylindrical outer case 9b having a brim 9a and a cylindrical inner case 9C.
The screen 8 is held between the inner surface of the collar 9a and one edge of the inner case 9C, and the other edge of the outer case 9b is caulked to fix the terminal plate 6.7 with the other edge of the inner case 9C. are doing.

Further, the bimorph vibrator 3 is attached to the vibrator support portion 6a using an elastic adhesive 5 so as to support the nodal portions so that the bimorph vibrator 3 can vibrate freely around the periphery.

In addition, this electroacoustic transducer has soft lead wires 10 on both electrode surfaces of the bimorph vibrator 3 that do not suppress the vibrations.
．． 11 is attached by soldering, and the other end is connected by soldering to terminals 12 and 13 implanted in the terminal plates 6 and 7, thereby inputting and outputting electrical signals from the bimorph vibrator 3.

However, in such a conventional electroacoustic transducer, the bimorph vibrator 3 is attached to the vibrator support portion 6a using an elastic adhesive 5.
Because it is carried out through It had become.

In addition, lead wires 10.11 and terminals 12.13 were required for electrical signal input/output, and it was also necessary to solder at four locations, which increased the number of parts and manufacturing processes, resulting in higher costs. There was a problem.

Therefore, an object of this invention is to provide an inexpensive electroacoustic transducer with a simple configuration and stable sensitivity-frequency characteristics.

An embodiment of this invention is shown in FIGS. 2 and 3.

That is, this electroacoustic transducer includes a piezoelectric ceramic vibrator 14
A bimorph oscillator 16 is formed by laminating a metal diaphragm 15 on one side, and a thin elastic terminal 17 integrally formed with the metal diaphragm 15 and an elastic diaphragm 17 laminated on the other side of the piezoelectric ceramic oscillator 14. The thin ring-shaped terminals 18 are connected and fixed to external terminals 20 and 21 implanted in the terminal block 19, respectively, and a metal conical resonator 22 is attached to the center of the open surface of the metal diaphragm 15. , these are housed in a cylindrical case 23 and fixed by caulking.

In this case, the terminal 17 is connected to the notch 15 in the metal diaphragm 15.
By providing the portion a, the portion protrudes from a portion corresponding to a node (vibration mode) of bending vibration that does not suppress bending vibration.

Similarly, the terminal 18 is bonded in a ring shape to a portion corresponding to a node of bending vibration so as not to suppress bending vibration.

Further, the metal conical resonator 22 is the bimorph resonator 1
In addition to having the function of amplifying the vibrations of the bimorph vibrator 16, the material and shape are set to match the natural acoustic impedance of the air when the vibrations of the bimorph vibrator 16 are radiated into the air as sound waves, thereby increasing acoustic efficiency. are doing.

Furthermore, the case 23 has a flange 23a, and the screen 25 is held between the inner surface of the flange 23H and a resonant tube 24 mounted inside the case 23.

On the other hand, the resonant tube 24 has an internal shape with a minimum inner diameter of 10 mmφ,
The terminal block 19 has a trumpet shape with a maximum inner diameter of 14 mmφ and a height of 2 mm to enhance the air resonance effect, and the terminal block 19 corresponds to the vibration mode diameter of the bimorph resonator 16 and has a depth of 4 mm (wavelength (at 40 KHz)/ 2] recess 1
9a is provided in the central portion to cause standing wave resonance using reflected waves, each of which acts to increase sensitivity.

In this way, this electroacoustic transducer has a simple structure in which thin elastic terminals 17.18 are provided on the bimorph vibrator 16, and these terminals 17.18 are fixed by external terminals 20.21, as shown in FIG. As shown in A and B, the bending vibration of the bimorph vibrator 16 is set to a vibration mode that approximates free vibration.

In addition, in Fig. 4 A and H, the broken line indicates the infinite baffle A.
,,Figure 5A shows the vibration mode when installed in A2.
, B and FIGS. 6A and B, and FIGS. 5 and 6 show a state in which the north terminals 17 and 18 are thickened, and in this case, bending vibration becomes free vibration. The vibration mode is far from the

In addition, in this electroacoustic transducer, the bimorph vibrator 16 is fixed to the terminal block 19 without using elastic adhesive, so the mounting position and dimensions can be set accurately, and as a result, the sensitivity-frequency characteristics are improved. Stabilize.

This sensitivity-frequency characteristic can be arbitrarily set by changing the shape of the metal conical resonator 22 or the shape inside the case 23.

That is, the sensitivity-frequency characteristics of the electroacoustic transducer in the shape of this embodiment are as shown by the solid line B1 in FIG. 7 and the solid line C1 in FIG. 8. When resonators having cross-sectional shapes as shown in A and B are used, the sensitivity-frequency characteristics become as shown by the broken line B2 and the dashed-dotted line B3 in FIG. 7, respectively.

On the other hand, if the metal conical resonator 22 is used as is and the inside of the case 23 has a cross-sectional shape as shown in FIGS.
2 and a dashed line C3.

Another embodiment of this invention is shown in FIG.

That is, in this electroacoustic transducer, the terminals 17, 18 and external terminals 20, 21 are integrated, thereby further simplifying the configuration, facilitating manufacturing, and reducing costs. Instead, a cylinder 26 is used to fix the screen 25 and the terminal block 19.

Note that the other configurations and effects are the same as those of the above-mentioned embodiments.

In addition, in the description of the above-mentioned embodiment, the metal diaphragm 1
Although the shapes of 5 and the piezoelectric ceramic vibrator 14 are substantially rectangular, they are not limited to this and may be circular.

Further, the terminal 18 has a ring-shaped attachment portion to the bimorph vibrator 16, and is attached to the entire circumference of the portion corresponding to the nodal circle of the vibration mode, but it may be attached only to a portion.

Furthermore, the metal conical resonator 22 may be made of resin instead.

As described above, in the electroacoustic transducer of this invention, a metal diaphragm is bonded to one side of a piezoelectric ceramic oscillator to form a bimorph oscillator. The first terminal is integrally formed, the second terminal is provided at the part corresponding to the vibration mode node of the piezoelectric ceramic vibrator, and these terminals are fixed to the terminal block and housed in the case. This simplifies manufacturing, resulting in cost reductions.Moreover, since the conventional elastic adhesive is no longer required, the mounting condition of the bimorph resonator remains constant and the sensitivity-frequency characteristics are stable. It has the effect of

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional electroacoustic transducer, Fig. 2 is a sectional view of an embodiment of the invention, Fig. 3 is an exploded perspective view of its main parts, and Fig. 4 is an explanatory diagram of its operation. 5 and 6 are operation explanatory diagrams of the comparative example, FIGS. 7 and 8 are sensitivity-frequency characteristic diagrams of this example, respectively, and FIGS. 9 and 10 are diagrams of the operation of the comparative example, respectively. FIG. 11 is a schematic cross-sectional view showing the shape of the resonator and the shape inside the case after considering the sensitivity-frequency characteristics of FIG. 11, and FIG. 11 is a cross-sectional view of another embodiment of this invention. 14... Piezoelectric ceramic vibrator, 15... Metal diaphragm, 16... Bimorph vibrator, 17
．． 18...Terminal, 19...Terminal block, 2
0, 21...External terminal, 22...Metal conical resonator.

Claims (1)

[Scope of utility model registration request] A bimorph vibrator in which a piezoelectric ceramic vibrator and a metal diaphragm are laminated together, a first terminal integrally formed at a vibration mode node portion of the metal diaphragm, and a vibration mode node portion of the piezoelectric ceramic vibrator. An electroacoustic transducer comprising: a second terminal adhered to a second terminal; and a terminal block for fixing the first and second terminals.