JPS62120799A - Ultrasonic transducer - Google Patents

Abstract

PURPOSE:To improve the radiation efficiency of the acoustic energy from an oscillator by providing an acoustic matching plate made of epoxy resin on the front surface of the oscillator and a rear surface material with an acoustic impedance close to that of air on the rear surface of the oscillator. CONSTITUTION:The acoustic matching plate 4 made of a synthetic resin whose thickness is lambda/4 is provided on the front surface of the oscillator 2 to seclude the oscillator 2 from a radiation medium 7. This is for the two purposes of protecting the oscillator 2 against the radiation medium 7 and acoustically matching the oscillator 2 and the medium 7. A material which is a mixture of epoxy resin and powdered cork in proportion of 4:3 and has the acoustic impedance close to that of air not to limit the oscillating phenomenon of the oscillator 2, is formed and applied to the rear surface of the oscillator 2. The improvement in gain of one transducer due to the above described acoustic- impedance matching is approximately 4.9db.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic transducer (hereinafter referred to as an l-transducer) for measuring distance, for example, underwater, and in particular to acoustic impedance matching with a radiation medium.

[Conventional technology]

FIG. 2(A) is a front view of a citransducer proposed by the applicant for which the applicant has already applied for a patent.1. Ia is the transducer arranged above and below, 2 is the vibrator of each transducer, 3 is a case that houses the two transducers, 6 is the cable that connects the transducers, 7 is the radiation medium, and ( B) is a bottom view of the transducer, and FIG. 3 is a connection diagram of a conventional transducer, in which the vibrator 2 is connected to a transceiver 9 via an impedance matching transformer 8 by a parallel connection cable 6.

FIG. 4 shows the radiation beam directivity characteristics of the transducer, in which the first radiation beam 11. The second radiation beam 12.13 with the sound pressure half-reduction angle θ on the right side is the combined radiation beam, and FIG. is a radiation medium, and 14 is a front plate of the vibrator. A conventional transducer is constructed as described above, and includes, for example, two transducers 2.
Transducer 1, 1a transmits ultrasonic waves underwater □
In order to achieve efficient reception, the beam width of the radiation beam directional characteristic of the transducer is widened, the side lobe level is lowered, and impedance matching between the electric circuit and the vibrator is performed. .

[Problem that the invention seeks to solve]

With conventional transducers such as those mentioned above, even if the beam width and side lobe level are optimized and the impedance of the electric circuit and the vibrator is matched, the transducer 1, 1
If the acoustic impedances of the transducers 1 and 1a cannot be matched with water, which is the radiation medium 7, the acoustic energy from the transducers 1 and 1a cannot be sufficiently transmitted into the radiation medium 7, resulting in insufficient transmission and reception sensitivity.

[Means for solving problems]

In the transducer according to the present invention, an acoustic matching plate between the vibrator and the radiation medium having a thickness of λ/4 is provided on the front surface of the vibrator in the transducer, and a backing material made of a material with low acoustic impedance is attached to the rear surface of the vibrator. It is something that

[Effect]

In this invention, a matching plate with a thickness of λ/4 is provided on the front surface of the vibrator for acoustically matching the radiation medium and the vibrator, and the rear surface of the vibrator is made of a material with an acoustic impedance isometrically close to that of air. Since the vibrator is suspended, there is little acoustic energy loss between the vibrator and the radiation medium, and the acoustic energy toward the rear is radiated toward the rear due to the mismatch in acoustic impedance between the vibrator and the backing material. Since the acoustic energy is reflected toward the front surface, the acoustic energy radiated from the vibrator is efficiently radiated into the radiation medium. Further, in another invention of the present invention, the acoustic matching plate has fluidity synthesis 4! Since J resin is used, it fits into the recessed groove on the inner peripheral surface of the case and prevents peeling.

〔Example〕

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, which is the same as the conventional device described above except for 4.5.

An acoustic matching plate 4 made of composite material 1111 with a thickness of λ/4 is provided in front of the vibrator 2. This has two purposes: to isolate the vibrator 2 and the radiation medium 7 and protect the vibrator 2 from the radiation medium 7, and to perform sound matching between the vibrator 2 and the radiation medium 7.

For example, when the material of the vibrator 2 is p z 'r and the radiation medium 7 is water, the acoustic impedance of the acoustic matching plate 4 is Z =
f 10,000 =;, J: ') Z = 65 X 10'
(kg/m”s) To'Cru Zo... Acoustic impedance of water 15X 10'(kg/m"・S) ZM...
・Vibrator acoustic impedance 284X 10' (kg
/ Go・S) The material close to this acoustic impedance is epoxy resin (Z = 32X 10' (kg / tr
l″・S)).When the frequency is 100 kHz,
By providing an epoxy resin with a thickness of 6.7 mm and a thickness of 6.7 mm between the vibrator 2 and the radiation medium 7, the acoustic impedance of the vibrator 2 and the radiation medium 7 can be matched, so that the vibration The loss of acoustic energy transmission from the element 2 to the radiation medium 7 is small. In addition, an acoustic impedance mite/stress (0,004 x 10' (kg/
rn' .S)) A material that does not limit the vibration phenomenon of the vibrator 2 is used, for example, a material mixed and molded in a ratio of 4 parts epoxy resin to 3 parts cork powder. As a result, the mismatch in acoustic impedance between the vibrator 2 and the snow surface material 5 becomes significant, and most of the acoustic energy toward the rear of the vibrator is reversed and propagates toward the front of the vibrator, and the acoustic energy radiated toward the front. Since most of the energy combined with the energy and thus radiated equally in the front and rear directions of the vibrator is radiated in the front direction, the effect of improving the radiation efficiency is large. The gain improvement per transducer due to the acoustic impedance matching is approximately 4.9 ad. In addition, the transducers 1 and 1a include a vibrator 2 and a cable 6.
Impedance matching with the electric circuit (improved 10 db) using an impedance matching transformer 8 at the connection position and the first radiation beam 11 of the transducer 1, 1a
A wide beam width 13 (
The integrated state of this transducer is significantly improved by forming a sound pressure half angle θ (4 times the sound pressure half angle θ) and lowering the side lobe level (improved to 8.5 db). In addition,
The acoustic matching plate 4 is provided with a recessed groove 3a in the shape of a wedge or semicircle on the inner peripheral surface at the position of the matching plate in the case, injected with fluid epoxy resin, and after solidifying, the thickness of the epoxy resin is set to a predetermined thickness of λ/4. Equivalent performance can be obtained with a structure formed to size.

〔Effect of the invention〕

As explained above, this invention uses an epoxy m resin acoustic matching plate on the front side of the vibrator and a backing material with an acoustic impedance close to that of air on the rear side, thereby significantly increasing the radiation efficiency of acoustic energy from the vibrator. There is an effect that can be improved. Additionally, this transducer provides proper radiation beam formation underwater, side lobe reduction, and impedance matching between the transmitter/receiver and transducer, so the overall performance is significantly improved in conjunction with the present invention.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a transducer showing an embodiment of the present invention, Fig. 2 is an overview diagram of a conventional transducer showing the arrangement of the transducer, Fig. 3 is a connection diagram of a conventional transducer, and Fig. 4 is an ultrasonic radiation beam directional characteristics,
FIG. 5 is an explanatory diagram of a conventional transducer. In the figure, 1. la is an ultrasonic transducer, 2 is a vibrator, 3 is a case, 3a is a concave groove, 4 is an acoustic matching plate,
5 is a backing material, 6 is a cable, 7 is a radiation medium, 8 is 1-lance for impedance matching, 9 is a transceiver, 10 is a reference direction, 11 is a first radiation beam, 12 is a second radiation beam,
13 is a radiation beam, and 14 is a front plate. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Patent Attorney Tadashi Sato Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Procedural Amendment (A) January 24, 1985

Claims (2)

[Claims] (1) Two ultrasonic transducers whose horizontal directional beams are deviated by half the sound pressure angle to the left and right with respect to the reference direction and arranged above and below, and an impedance matching device installed in the case housing the ultrasonic transducers. An ultrasonic transducer comprising: an acoustic matching plate having a thickness of λ/4 on the front surface of the vibrator of the ultrasonic transducer; and a backing material having an acoustic impedance close to that of air on the rear surface. (2) The ultrasonic transducer according to claim 1, wherein the acoustic matching plate is formed by molding a fluid synthetic resin.