JPS6143898A - Electroacoustic transducer - Google Patents

Abstract

PURPOSE:To transmit a wave with a small parabolic area under large sound pressure by jointing plural electromechanical transducers to a common diaphragm, and sending mechanical vibrations of these transducers to different directions with each other. CONSTITUTION:A diaphragm 1 is constituted in such a way that a cylinder made of high rigidity materials is divided in the vertical direction. An actuator 2 composed of piezoelectric vibrators, etc., is inserted into the end of the diaphragm 1 and a fixed shaft 3 of the interior of the cylinder. The number 4 in the figure means a holding ring of the diaphragm 1. Thus the displacement due to the expansion and contraction of the actuator 2 is enlarged, and appears as the displacement of the diaphragm 1. By the displacement amount, the diaphragm 1 carries out the breath vibration. Consequently, when the vibration and displacement of the actuator 2 are enlarged to emit an acoustic sound, the sound pressure several times larger than the conventional one can be produced.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a burst acoustic transducer (referred to as a vibrator in the field of sonar technology) used in an underwater transducer.
In particular, the present invention relates to a burst acoustic transducer for transmitting waves used at low frequencies.

BACKGROUND OF THE INVENTION This type of sound transducer converts electrical vibrations into mechanical vibrations, transmits the mechanical vibrations into the water, and transmits sound waves into the water. Conventional electroacoustic transducers transmit vibrations of electromechanical transducers (eg, piezoelectric ceramics) that convert electrical vibrations into mechanical vibrations into water. For example, a conventional cylindrical acoustic transducer has a cylindrical shape made of piezoelectric ceramic, and emits sound waves by its breathing vibration (vibration that expands and contracts the diameter of the cylinder). In order to efficiently radiate sound waves into water, it is necessary to increase the area of the vibration surface compared to the wavelength and increase the radiation impedance density.

However, when the frequency used is low, the wavelength becomes long and the area of the vibration surface required to obtain sufficient radiation impedance density becomes very large.

For example, at a frequency of 10 KHz, a diameter of 10 cm and a height of 5
Even if a cylindrical electroacoustic transducer with a diameter of 1 m^ and 50 cWL is required to obtain the radiation impedance density f I Kl (z) equivalent to that obtained with a cylindrical electroacoustic transducer of cTn, this: It is very inconvenient to increase the number of wavelengths.Conventionally, an electroacoustic transducer with a small radiation area compared to the wave length has been used.

At this station 1, the radiation impedance density is low, so the mechanical sound conversion efficiency is low. Therefore, in order to obtain the full predetermined transmitted sound output using a conventional electroacoustic transducer with a small radiation area, it was necessary for the VC to apply a high voltage to the EJ (female ceramic) to generate a large vibration displacement.

(Problem to be Solved by the Invention) Niro said that if an excessive voltage is applied in an attempt to obtain a large vibration displacement using an electroacoustic transducer with a small radiation area, the characteristics of the ceramic will deteriorate. , power consumption 300V
The application of a stone field of about zim was the limit, and the vibration displacement and, by extension, the transmitted sound pressure were also limited by kneading.

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide an electric sound transducer which solves the above-mentioned drawbacks and can transmit waves with a large sound pressure even when the radiation area is small.

(Means for Solving the Problems) The electroacoustic transducer according to the present invention includes a plurality of transducers that convert electrical vibrations into total mechanical vibrations, and these converters are connected to convert the mechanical vibrations into sound. It must be equipped with a diaphragm.
The mechanical vibrations of the transducer are at least two different from each other.
It is characterized by being done in one direction.

(Function) In the present invention, there are two or more converters (air-mechanical converters) that convert electrical vibrations into mechanical vibrations, and these are connected to a common diaphragm. Vibration 2
More than one, done in the upward direction.

Therefore, the displacements of a plurality of electromechanical transducers are combined in the diaphragm, and the distance between the connecting points of the diaphragm and the mechanical transducers remains unchanged. The displacements of the mechanical transducer in different directions are then magnified at the diaphragm. Therefore,
With the present invention, a vibration displacement 1 larger than the vibration displacement of the electromechanical transducer can be caused in the diaphragm.

(Example) Next, embodiments of the present invention will be described with reference to all the drawings.

FIG. 1 is a plan view of a cylindrical electroacoustic transducer which is a 1''A embodiment of the present invention; FIG. 1 is a side view thereof.

Here, the diaphragm 1 has a structure in which a cylinder made of a highly rigid material such as metal is divided in the direction of the edge.
It is inserted between the end of the diaphragm J and the fixed shaft 3 inside the cylinder. A protective ring for holding one 41 diaphragm, made of rubber, silastic, r; np '51
The diaphragm 1 is made of a flexible material such as metal that does not completely hinder the lifting movement of the diaphragm 1, and the diaphragm 1 is tightened and held from the outer peripheral surface.

FIG. 2 is a diagram showing the operating situation of the embodiment in FIG. 1,
Here is an enlarged view of a portion of Figure 1. I'm here,
The solid line shows the state in which the actuator 2 is contracted, and the broken line shows the state in which it is extended, and the displacement of each part between the contracted state and the extended state is shown in an enlarged manner. Since the diaphragm 1 is made of a highly rigid material, it moves in the radial direction without being deformed.

FIG. 3 is a diagram obtained by flattening FIG. 2 with a skeleton.

Here, IVi indicates the length of the actuator 2 in the contracted state, 1' indicates the length of the actuator 2 in the extended state, and indicates the displacement of the dit diaphragm 1. 1 in this figure is a line drawn hypothetically as a string connecting both ends of the diaphragm 1, and has a half length kL. Now, l ” 5 a
If n, L = 4.8cm, when actuator 2 extends 0.01cm, id I' = 5.01
It becomes certain. At this time, d is expressed by the following equation.

d = Q+'-L2-712-L2 Therefore, d = 0.0353 cm. That is, the displacement of the actuator 2 is expanded by about 3.5 times, and the diaphragm 1 moves. It is clear from the above equation that this enlargement ratio can be freely changed by appropriately determining 1 and L. As a result, in the embodiment shown in FIG. 1, the displacement caused by the expansion and contraction of the actuator 2 is magnified, and the diaphragm 1 performs breathing vibration with the expanded displacement amount.

As explained above, in this embodiment, if an electric field equivalent to the conventional one is applied to the actuator 2 (piezoelectric ceramic, etc.) by expanding the vibration displacement of the actuator 2 and performing acoustic radiation, the conventional 144, Ml's ability is to generate a sound pressure several times greater than that of an air sound transducer. Therefore, in order to increase the radiation impedance density, a very large transmission t? By using this embodiment, even if the transmitter is small, the necessary high sound pressure can be obtained by driving the transmitter with a large amplitude, without making a transmitter.

(Effects of the Invention) As explained in detail above, the present invention can provide an electroacoustic transducer capable of transmitting waves with a large sound pressure even if the radiation surface is as small as t/l.

[Brief explanation of the drawing]

FIG. 1 (al is a plan view showing one embodiment of the present invention,
b) is a top view, FIG. 2 is a partial plan view showing the operating situation of the embodiment, and FIG. 3 is a diagram showing the entire skeleton of FIG. 2. 1... Vibrator, 2... Actuator, 3...
Fixed shaft, 4...retaining ring. Agent: Susumu Uchihara, patent attorney (−ゝ゛・,■,
1 Figure 1 Figure 82 Figure 3

Claims (1)

[Claims] A plurality of transducers that convert electrical vibrations into mechanical vibrations are provided, and a diaphragm that is connected to these transducers and converts the mechanical vibrations into sound is provided, and the mechanical vibrations of the transducers are at least two different from each other. An electroacoustic transducer characterized in that it is made in two directions.