JPH0562706B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electroacoustic transducer for sonar, and more particularly to an electroacoustic transducer for use in a sonar system for detecting the distance and direction of a target.

[Conventional technology]

This type of electroacoustic transducer that has been proposed in the past (for example, Japanese Patent Application No. 56-126185) has electrodes 9a, 9 on the outer diameter surface of a cylindrical piezoelectric element 8, as shown in FIG.
b, 9c, 9d are provided separately, and electrodes 10a, 10b, 10 are provided on the inner diameter surface of the cylindrical piezoelectric element 8.
c, 10d are provided to form a pair with electrodes 9a, 9b, 9c, 9d, and as shown in FIG.
b, 10b, 9d, and 10d are connected so that the polarity of polarization is reversed in the radial direction of the cylindrical piezoelectric element 8 to obtain dipole directivity, and at the same time, the midpoint of the oppositely connected electrode pair and the balance of the termination circuit are obtained. Type transformer 11a, 11
Omnidirectionality was obtained from the midpoint of b.

In FIG. 4, electrodes 9a, 10a, 9c, 10
The terminal of the balanced transformer 11a to which c is connected is
The terminals of the balanced transformer 11b to which the electrodes 9b, 10b, 9d, and 10d are connected are the Y-direction dipole directional terminals 13a and 13b, and the terminals of the balanced transformer 11b to which the electrodes 9b, 10b, 9d, and 10d are connected are the Y-direction dipole directional terminals 13a and 13b. The dot is the omnidirectional terminal 14
a, 14b.

[Problem that the invention seeks to solve]

However, since the vibrator used in the conventional electroacoustic transducer described above has separate electrodes on the inner diameter surface and the outer diameter surface, it is time-consuming and expensive to manufacture.

Furthermore, in the case of omnidirectional connection, 14a in Fig. 4
As seen from and 14b, the divided electrodes (hereinafter referred to as divided electrodes) are arranged in parallel with 9b, 10b and 9d, 10.
d and 9a, 10a and 9c, 10c and series 9
b, 10b, 9d, 10d and 9a, 10a, 9
c, 10c, the impedance becomes higher than when all divided electrodes are connected in parallel, and the driving voltage during wave transmission becomes higher.

[Means for solving problems]

The acoustoelectric transducer of the present invention is an electroacoustic transducer using a vibrator made of a cylindrical piezoelectric element having electrodes on an inner diameter surface and an outer diameter surface and polarized in the radial direction. One of the electrodes on the surface is a full-surface electrode, the other electrode on the inner diameter surface or the outer diameter surface is an electrode divided into 2n pieces (n is an integer) in the circumferential direction, and the divided electrodes are opposite to each other. A signal having dipole directivity in the direction in which the two electrodes face each other is transmitted from the secondary side of a balanced transformer in which two opposing electrodes are connected to both ends of the primary side for each n set of n sets. and obtaining an omnidirectional signal from between the point connecting the middle points of the primary sides of the n balanced transformers provided corresponding to the n sets of divided electrodes and the entire surface electrode. Features.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a perspective view of a vibrator used in an embodiment of the electroacoustic transducer of the present invention, in which a cylindrical piezoelectric element 1 has a full-surface electrode 2 on its outer diameter surface, and divided electrodes 3a, 3b on its inner diameter surface. , 3c, and 3d are provided.

FIG. 2 is a connection diagram of a converter according to an embodiment of the present invention, in which opposing electrodes 3a and 3c of the divided electrodes of the vibrator shown in FIG. 3b and 3d are connected to the primary side terminal of the second balanced transformer 4b, and the first
Secondary terminals 5a and 5b of the second balanced transformer 4a serve as dipole directional terminals in the X direction, and secondary terminals 6a and 6b of the second balanced transformer 4b serve as dipole directional terminals in the Y direction.

1 of 4a and 4b of the first and second balanced transformers
The terminal 7a drawn out by short-circuiting the middle point on the next side and the terminal 7b drawn out from the entire electrode 2 on the outer diameter surface of the vibrator become non-directional terminals.

When the vibrator in Figure 1 receives sound waves in a sound field, each piezoelectric element within the range of the opposing divided electrodes produces respiratory vibration due to the sound pressure difference between the outside and outside of the cylinder, and translational vibration due to the diffraction effect of the sound waves on the outer diameter surface of the cylinder. receive at the same time. If the polarization direction of the oscillator is constant in the radial direction,
Opposing divided electrodes, for example 3a and 3c, have the entire surface electrode on the outer diameter surface as a neutral point, and respiratory vibration signals appear in the same phase, and translational vibration signals appear in opposite phases.These divided electrodes 3a and 3c When connected in series so that the polarization direction is reversed and the signal is extracted through the balanced transformer 4a, the respiratory vibration signals that are in phase on the primary side are canceled out at the secondary side terminals 5a and 5b. As a result, only signals of translational vibrations having opposite phases are output, so that the split electrodes 3a and 3c are sensitive to sound waves from directions parallel to them, that is, the X direction and one Y direction. A so-called dipole directivity that is not sensitive to sound waves from the Y direction can be obtained.

Similarly, for the terminals 6a and 6b, the divided electrode 3b
Directivity of a dipole sensitive to directions parallel to and 3d, that is, the Y direction and one Y direction, can be obtained.

When a signal is extracted between the neutral point of the balanced transformers 4a and 4b and the entire surface electrode 2 on the outer diameter surface, the signal of the translational vibration that is in opposite phase between the opposing divided electrodes is canceled, and the signal of the respiratory vibration that is in the same phase As a result, omnidirectionality is obtained between terminals 7a and 7b.

Each divided electrode 3a, 3 is provided between the terminals 7a and 7b.
Since the electrical capacitances created between b, 3c, 3d and the entire surface electrode 2 are all connected in parallel, the impedance of the converter is reduced to about 1/4 compared to the conventional one.

〔Effect of the invention〕

As explained above, the present invention consists of making one of the inner and outer electrodes of the vibrator a full surface electrode and the other being a split electrode, and connecting all the split electrodes in parallel to obtain an omnidirectional signal. By this,
By using a vibrator that requires less effort to divide the electrodes, it is possible to create an inexpensive converter, and also to have the effect of lowering the impedance and making it possible to transmit low voltage omnidirectional waves.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a vibrator used in an embodiment of the present invention, FIG. 2 is a connection diagram of an embodiment of the present invention, and FIG.
The figure is a perspective view of a vibrator used in a conventional electroacoustic transducer, and FIG. 4 is a connection diagram of the conventional electroacoustic transducer. 1, 8...Cylindrical piezoelectric element, 2...Full surface electrode, 3a, 3b, 3c, 3d, 9a, 9b, 9
c, 9d, 10a, 10b, 10c, 10d...
Split electrode, 4a, 4b, 11a, 11b...Balanced transformer, 5a, 5b, 12a, 12b...X
Directional dipole directional terminals, 6a, 6b, 13
a, 13b...Y direction dipole directional terminal, 7
a, 7b, 14a, 14b...Omnidirectional terminals.

Claims (1)

[Claims] 1. In an electroacoustic transducer using a vibrator made of a cylindrical piezoelectric element polarized in the radial direction and having electrodes on the inner diameter surface and the outer diameter surface, the electrode on one of the inner diameter surface or the outer diameter surface is The entire surface is electroded, and the other electrode of the inner diameter surface or outer diameter surface is placed in the circumferential direction.
2 of a balanced transformer, in which the electrodes are divided into 2n pieces (n is an integer), and the two opposing electrodes for each of the n groups are connected to both ends of the primary side, with the opposing electrodes of the divided electrodes being one set. A signal having dipole directivity in the direction in which the two electrodes face each other was obtained from the next side, and the primary side midpoints of the n balanced transformers were connected corresponding to the n sets of the divided electrodes. An electroacoustic transducer characterized in that an omnidirectional signal is obtained between a point and the entire surface electrode.