JPH07322398A - Cylindrical transmitter-receiver - Google Patents

Abstract

PURPOSE:To realize a transmitter-receiver for sound waves which is capable of measuring the distance and direction of an object in all the directions. CONSTITUTION:By forming this transmitter-receiver by plural cylindrical shells 1a to 1c arranged in an axial direction and plural piezoelectric elements 2a to 2c arranged in the circumferential direction of the inside surface of each of the cylindrical shells 1a to 1c, the cylindrical shells 1a to 1c where vibrations are excited by the piezoelectric elements 2a to 2c transmit sound waves (p) in all the directions, the reflected waves coming because these sound waves (p) are reflected and scattered by the object are made incident to the piezoelectric elements 2a to 2c via the cylindrical shells 1a to 1c, the distance up to the object is determined from the time difference of the transmitter-receiver and the direction is determined from the phase difference of the reflected waves to which each of the piezoelectric elements 2a to 2c is made incident. As a result, a device which is capable of measuring the distance and direction of the object in all the directions with accuracy is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical transducer which is applied for underwater search and the like.

[0002]

2. Description of the Related Art A conventional transmitter / receiver attached to an underwater robot will be described with reference to FIG. The conventional apparatus shown in FIG. 3 is formed by attaching a plurality of ultrasonic vibrators 6 that generate longitudinal vibration to an acoustic rubber plate 7 provided on the front surface of the outer shell of the underwater robot 05. Was connected to an AC power supply (not shown).

In the above, when the ultrasonic transducer 6 is excited by an AC power source, a sound wave p having directivity 04b to 04c is generated.
Is radiated forward. When this sound wave p is reflected by the object, the vibrator 6 performs the opposite operation to receive the reflected wave, and the distance to the object and the direction of the object are measured.

[0004]

The conventional device has the following problems. (1) The directivity of transmitted / received sound waves is limited only to the front. (2) Efficient transmission / reception can be performed only at a frequency corresponding to the longitudinal primary natural frequency of the ultrasonic transducer. The present invention is intended to solve the above problems.

[0005]

SUMMARY OF THE INVENTION A cylindrical transducer according to the present invention is provided with a plurality of cylindrical shells arranged in the axial direction with the same central axis, and in the circumferential direction of the inner surface of each cylindrical shell. It is characterized in that it is formed by a plurality of piezoelectric elements provided.

[0006]

In the above, when transmitting a sound wave, an AC voltage is applied to the plurality of piezoelectric elements to excite the cylindrical shell in the resonance mode. Then, the cylindrical shell sends sound waves in almost all directions. In the case of receiving a sound wave, the opposite action is performed, and the sound wave coming from the outside excites and vibrates the cylindrical shell on which the piezoelectric element is mounted, and a voltage is generated in the piezoelectric element according to the distortion.

When a sound wave is obliquely incident, the phases of incident sound pressures acting on a plurality of cylindrical shells mounted with piezoelectric elements are different, and the phases of vibrations of the cylindrical shells are also different accordingly.
Thereby, the arrival direction (incident angle) of the sound wave is determined.
With the above, it is possible to transmit and receive waves in all directions, and it is possible to determine the arrival direction of sound waves.

[0008]

FIG. 1 shows an embodiment of the present invention. In the present embodiment shown in FIG. 1, a plurality of cylindrical underwater robots 5 are provided in the vicinity of the central portion thereof and are arranged at regular intervals in the axial direction with the same central axis to form an outer shell of the robot 5. Cylindrical shells 1a, 1b, 1c, and cylindrical shells 1a, 1b,
A plurality of piezoelectric elements 2a, 2b, 2c are arranged in two rows in the circumferential direction of the inner surface of 1c at predetermined intervals.

The circumferential shells 1a, 1b, 1c forming the outer shell of the underwater robot 5 have a watertight structure. The piezoelectric elements 2a, 2b and 2c are connected to an AC power source via a controller (not shown).

In the above, when transmitting a sound wave, the piezoelectric elements 2a, 2b, 1b, 1b, 1b, 1b, 1c are controlled through a controller so that the cylindrical shells 1a, 1b, 1c can easily excite a plurality of resonance modes.
An alternating voltage having a predetermined amplitude and phase is applied to 2c. Then, vibrations of the axially symmetric modes 3a, 3b, 3c as shown in FIG. 2 occur in the cylindrical shells 1a, 1b, 1c, and the sound pressure distribution 4
a, 4b, and 4c transmit the star-shaped sound wave p shown in FIG. Since the cylindrical shells 1a, 1b, 1c have a large number of resonance modes 3a, 3b, 3c, they can be transmitted at a large number of frequencies.

When receiving a sound wave, the operation is reverse to the above. That is, as shown in FIG.
When the scattered sound waves p _i enter the cylindrical shells 1a, 1b, 1c, the resonance modes 3a, 3b, 3c are excited, and the vibrations are detected by the piezoelectric elements 2a, 2b, 2c.

At this time, the plurality of cylindrical shells 1a, 1b, 1c
Since the phase of the sound wave incident on is changed according to the incident angle θ, the phase of vibration of each cylindrical shell 1a, 1b, 1c is also different,
By detecting it with the piezoelectric elements 2a, 2b, 2c, the incident angle θ of the incident sound wave p _i can be determined.

[0013]

The cylindrical transducer of the present invention is formed of a plurality of cylindrical shells arranged in the axial direction and a plurality of piezoelectric elements arranged in the circumferential direction of the inner surface of each cylindrical shell. As a result, the cylindrical shell whose vibration is excited by the piezoelectric element transmits sound waves in all directions, and the reflected wave that is reflected and scattered by the object is incident on the piezoelectric element through the cylindrical shell. The distance to the object is calculated from the time difference between the transmitted and received waves, and the direction is calculated from the phase difference between the reflected waves that are incident on each piezoelectric element, so the distance and direction of the object can be accurately measured in all directions. To realize a device that can.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the present invention, (a) is a side view, and (b) is a view taken along the line AA of (a).

FIG. 2 is an explanatory diagram of an incident wave according to the above embodiment.

FIG. 3 is an explanatory diagram of a conventional device.

[Explanation of reference symbols] 1a, 1b, 1c Cylindrical shells 2a, 2b, 2c Piezoelectric elements 3a, 3b, 3c Resonance modes 4a, 4b, 4c Sound pressure distribution 5 Underwater robot

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G01S 7/523 // G05D 1/00 A

Claims (1)

[Claims] 1. A plurality of cylindrical shells, which have the same central axis and are arranged in the axial direction, and a plurality of piezoelectric elements, which are respectively arranged in the circumferential direction of the inner surface of each cylindrical shell, are formed. Characteristic cylindrical transducer.