JPS5824998B2 - Chiyo Onpa Souji Yuhaki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION For example, in the Dobrunner, as shown in FIG.
The transducer 21 is placed on the bottom 1 of the ship in its orientation direction α with respect to the vertical direction.
It is installed at an angle.

In order to sharpen the directional characteristics in the α direction, a plurality of oscillators 21 and 22 are arranged so that the sound waves arrive at each oscillator in the same phase, and the combined directional characteristics are utilized. ing.

In the above, it is desirable that the vibrator has a directivity characteristic only in the α direction, and especially when used in a dovetail runner, it is necessary to minimize pressure sensitivity of the vibrator in the vertical direction.

Conventionally, each vibrator was designed so that the vertical pressure sensitivity was as small as possible.

Therefore, when using the composite directional characteristics of each oscillator, α
There is a drawback that the directional characteristics become sharp and the pressure sensitivity in the vertical direction also increases to some extent.

The present invention provides a transducer in which the directivity in a predetermined direction is sharp in the composite directional characteristics of each vibrator, and at the same time, the pressure sensitivity in the vertical direction is smaller than that of a single vibrator. be.

To explain the present invention in detail below, in the case of the vibrator 21, for example, a rectangular vibrator, it is expressed by its directivity.

Here, if the dimension of the vibrator is 11, then Xl is expressed as.

However, when xl=nπ (n=1.2.3=”)”・”(3) in equation (1) where λ=wavelength of sound wave, the directivity coefficient F(XI) is pi(xt)=.

The transmitting and receiving sensitivity becomes zero.

Also, the direction θ is X1=nπ From equation (2), the angle θ that satisfies It is required as.

Therefore, as shown in Figure 1, when transmitting and receiving ultrasonic waves in the α direction, by setting the transducer dimensions 11 so that α=θ, the vertical sensitivity of the transducer 21 can be minimized. It can be done.

In the above, when equation (2) is substituted into equation (1), the directivity coefficient for the wave transmission/reception direction θ is obtained.

This directivity coefficient F, (θ) is expressed by a characteristic curve as shown in FIG. 2A.

In this characteristic curve A, a positive phase signal is transmitted and received in a region where the directivity coefficient F, (θ) is positive, and a negative phase signal is transmitted and received in a negative region.

Also, θ, 1. θ, 2. θ19. θ14 indicates the zero point of the directivity coefficient at which the transmitting/receiving sensitivity becomes zero, and its direction is determined from equation (4).

Therefore, in the characteristic curve A, the directivity coefficient zero point θ, 1.
θ12. θ, 3. The transducer dimension 11 depends on which of θ and 4 corresponds to the vertical direction α in FIG.
is determined.

For example, in equation (3), when n = 4, the zero point θ14 is determined to coincide with the vertical direction α.

On the other hand, in the vibrator 22 as well, the directivity coefficient F, (θ) with respect to the wave transmission/reception direction θ is given by (
5) It is expressed as from Eq.

This directivity coefficient F2(θ) is expressed by the characteristic curve shown in Figure 2B, and in equation (5) 7, x2=nπ (n=1, 2, 3, 4...)...
- When (3)', the zero point of the directivity coefficient θ21. θ22.
θ, 3° θ24 is given.

Therefore, as in the case of characteristic curve A, the directivity coefficient zero point θ
21. θ, 2. θ23. The transducer dimension 12 is determined depending on which of θ and 4 corresponds to the vertical direction α in FIG.

For example, in equation (3) 7, when n=3 is set, the zero point θ23 is determined to coincide with the vertical direction α.

When the transducer dimensions X, ,
coincides with the vertical direction α, and in the characteristic curve B, the zero point θ2
° coincides with the vertical direction α.

Therefore, when characteristic curves A and B are expressed on a common θ axis, as shown in FIG. 3, zero point θ14 of characteristic curve A and zero point θ2 of characteristic surface mB. coincide on the θ axis.

Therefore, as mentioned above, if n in equation (3) is set to an even number for the oscillator 21, and n in equation (3)7 is set to an odd number for the oscillator 22, it is clear from FIG. As shown in the figure, the phase relationships in the respective directional characteristics are opposite to each other in the vicinity of the vertical direction α.

As a result, the composite directivity (average value) of each vibrator becomes as shown by characteristic curve C, and the directivity of each vibrator cancels each other out in the vertical direction, making it as small as possible.

As described above, in the present invention, the composite directivity characteristic of each vibrator becomes large only in the predetermined direction α, and can be made small in unnecessary directions.

Therefore, a transducer suitable for use in Doppler sonar and the like can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the operation of the transducer, and FIGS. 2 and 3 show characteristic curves for explaining the present invention.

Claims (1)

[Claims] , 5inX πl. 1 Each directivity function - [However, x = T (λ of S1n
is the wavelength of the sound wave, and l is the transducer dimension.] A pair of transducers are tilted by α with respect to the vertical direction and arranged so that the sound waves arriving at each transducer are in phase. In an ultrasonic transducer that uses composite directional characteristics, the dimension 11 of one of the pair of transducers is x=2.
ng', (n-1, 2, 3...) and set the dimension 12 of the other vibrator to x-(2n-1)π, An ultrasonic transducer characterized by minimizing composite directional characteristics.