JPS5851478B2 - directional receiver - Google Patents

Description

[Detailed description of the invention] The present invention relates to a compact and highly sensitive directional receiver.

As shown in FIG. 1, a conventional directional wave receiver of this type includes an inner member 1, a plurality of cantilevers 2 and a ceramic piezoelectric element 3 attached to the inner member 1, and a potting mold portion surrounding them. 4, and the plurality of cantilevers 3 vibrate with the internal member 1 as a fulcrum in response to incoming underwater sound waves.

However, the directional receiver having the above configuration has drawbacks such as changes in the receiver characteristics due to changes in the potting mold due to water pressure at the depth of use, and deterioration of directivity at low frequencies.

The present invention is characterized by arranging a plurality of vibrometers in a case, the internal material of which is supported within the housing by two diaphragms to which piezoelectric elements are attached. The goal is to obtain a sexual receiver.

An embodiment of the present invention will be explained with reference to FIGS. 2 to 5.
In FIG. 2, 5 is a hanging rubber, 6 is a cylindrical case made of metal or plastic, etc., and 7 is a vibration meter, and a plurality of vibration meters 7 are arranged in the case 6 in a right angle direction. has been done.

In this configuration, the case 6 vibrates due to the sound pressure difference applied to the case 6 underwater, and the vibration is picked up by the vibration meter 7.

Each vibrometer is sensitive only to vibrations in its axial direction;
The outputs of the vibrometers 7 facing each other in the case 6 are connected in series to form a wave receiver having two pairs of figure-eight pattern directivity.

The structure and operation of the vibration meter 7 will now be explained in detail with reference to FIG.

In the figure, 8 is a cylindrical housing, 9 and 10 are disc-shaped diaphragms, 11 and 12 are disc-shaped piezoelectric elements made of ceramic or the like, 13 is a cylindrical internal member made of lead or the like, and 14 is a cylindrical internal member. Indicates a viscous liquid such as oil.

The inner member 13 has piezoelectric elements 11 and 12 at both ends thereof, respectively.
It is supported by diaphragms 9 and 10 to which is pasted, and is housed in the center of the housing 8.

The peripheral edges of the diaphragms 9 and 10 are fixed to the inner wall of the housing 8 by adhesive or the like, and the viscous liquid 14 is filled between the diaphragms 9 and 10.

In the vibrometer 7 configured in this way, the casing 8 vibrates in the same manner as the case 6 described above, and the vibration is transmitted to the internal member 13 via the diaphragms 9 and 10, and the casing 8 and the internal member 13 vibrate. The difference in movement causes the piezoelectric elements 11, 12 to bend and produce an output voltage.

At this time, the piezoelectric elements 11 and 12 are bent in opposite directions, so by connecting them in reverse, the sensitivity can be doubled.

Next, the receiving sensitivity and frequency characteristics of the directional receiver having the above configuration will be explained.

The sound reception type of the case 6 is a pressure gradient type, and since it operates in a mass control region by the hanging rubber 5, the response of vibration velocity to sound pressure is constant within the frequency band used.

On the other hand, inside the vibration meter 7, the mass of the internal material 13 and the diaphragm 9 are
, 10, and the response of the displacement of the diaphragms 9 and 10 to the speed of the housing 8 is the natural frequency f of the vibration system, as shown in FIG.

Below it has a slope of +6 dB/octave and f.

In the above example, the phase characteristic has a slope of -6 dB/octave as shown in FIG.

Furthermore, the piezoelectric elements 11 and 12 with respect to the displacement of the diaphragms 9 and 10
Since the output voltage response of is independent of frequency, the responses of FIGS. 4 and 5 are also the responses of the directional receiver with the configurations of FIGS. 2 and 3.

Further, the viscous liquid 14 controls the Q value of the resonance characteristic by its viscosity.

In the above-described embodiment, four vibrometers are used, with the vibrometers facing each other connected in series, but the same effect can be obtained even if two vibrometers are arranged at right angles.

As explained above, the present invention has a structure in which a plurality of vibrometers each having an inner member supported within a housing by two diaphragms to which piezoelectric elements are attached are arranged in a right angle direction within a case. It is a directional receiver with high sensitivity and stable characteristics, and the frequency response has a slope of +6 dB/octave at low frequencies, so it has characteristics that are opposite to the frequency spectrum of underwater noise, so it can be used as an underwater directional receiver. There are also advantages such as no need for a flower vase.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a conventional example, FIG. 2 is a perspective view showing an embodiment of the present invention, FIG. 3 is a cross-sectional view showing the structure of a vibration meter used in the present invention, and FIGS. The figure shows the frequency response of a directional receiver according to the invention. 5... Hanging rubber, 6... Case, 7.
...Vibration meter, 8...Housing, 9,10...
...Diaphragm, 11,12...Piezoelectric, 13
...Internal material, 14...Viscous liquid.

Claims (1)

[Scope of Claims] 1. A plurality of vibrometers each including a housing, a diaphragm to which a piezoelectric element is attached, and an internal member supported at both ends by the diaphragm and housed within the housing are housed in a case. A directional receiver characterized in that it is configured by arranging individual pieces. 2. The directional wave receiver according to claim 1, wherein adjacent vibrometers are arranged so as to be perpendicular to each other. 3. The directional wave receiver according to claim 1, characterized in that a vibration meter is used in which a viscous liquid is filled between diaphragms that support both ends of an internal member.