JPS62154999A - Ultrasonic transmitter-receiver - Google Patents

Abstract

PURPOSE:To form a wide-band and horizontally nondirectional ultrasonic transmitter-receiver by providing at least one cylindrical or annular synthetic resin member whose thickness is about a quarter as large as the wavelength of underwater sound to the outer periphery of piezoelectric ceramic. CONSTITUTION:The cylindrical piezoelectric ceramic 6 is clamped with flanges 8a and 8b across spacers 7a and 7b and the cylindrical resin member 9 is provided to the outer periphery. The synthetic resin member 9 is about a quarter as thick as the wavelength of underwater sound, and its acoustic impedance is larger than the acoustic impedance ZL of water and smaller than the acoustic impedance ZO of the piezoelectric ceramic 6. Namely, when the acoustic impedance Z is the geometric mean (ZL.ZO)<1/2> between the acoustic impedance ZO and acoustic impedance ZL, the piezoelectric ceramic and water are matched with each other completely and wide band frequency characteristics are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic transducer used underwater, and more particularly to an ultrasonic transducer with a wide band transmission sensitivity frequency characteristic.

[Conventional technology]

Conventionally, this type of ultrasonic transducer combines a transmitter that excites and transmits ultrasonic waves using vibrations caused by piezoelectricity, and a receiver that receives υ ultrasonic waves using piezoelectricity. It was common to use cylindrical porcelain.

FIG. 2 is a configuration diagram showing an example of a conventional ultrasonic transducer. In FIG. 2, a cylindrical piezoelectric ceramic 1 is sandwiched between flanges 3a and 3b with spacers 2a and 2b interposed. The piezoelectric ceramic 1 is fixed with bolts 4, and the inside of the cylinder of the piezoelectric ceramic 1 is used as an air chamber. Further, a cable 5 serving as a signal line is connected to the piezoelectric ceramic 1, and a molding material 6 such as rubber is coated around the cable 5 as shown in FIG.

In such an ultrasonic transducer, the reception sensitivity frequency characteristics become flat at frequencies lower than the resonance frequency.

However, the transmission sensitivity frequency characteristic has a slope of 12 dB/oct, as shown by curve A in FIG. 3, and has a peak at the resonant frequency depending on the sharpness Q of the resonance. Note that since the ultrasonic transducer uses the cylindrical piezoelectric ceramic 1, the horizontal directivity is omnidirectional.

[Problem that the invention seeks to solve]

Therefore, when the above-mentioned ultrasonic transducer transmits a wideband signal, it is necessary to install a -12 dB/oct equalizer between the ultrasonic transducer and the signal source and use it below the resonant frequency. There is a problem in that a damper circuit must be provided between the ultrasonic transducer and the signal source and used near the resonant frequency.

The present invention was made to solve the above problem, and its purpose is to provide an equalizer and a Q-dunk.

It is an object of the present invention to provide a horizontally omnidirectional ultrasonic transducer in which the transmitting sensitivity frequency characteristics of the ultrasonic transducer itself are widened without providing a circuit.

[Failure to solve the problem]

In order to achieve the above-mentioned object, the present invention provides an ultrasonic transducer that can be used underwater by subjecting a piezoelectric ceramic having a cylindrical or annular shape to watertight treatment, the thickness of which is approximately 1 of the underwater acoustic wave length.
The present invention is characterized in that at least one cylindrical or annular synthetic resin member having a wavelength of /4 is provided on the outer periphery of the piezoelectric ceramic to perform watertight treatment.

[Effect]

In the present invention having the above characteristics, at least one synthetic resin member is provided around the circumference of the piezoelectric ceramic, and watertight treatment is performed using a molding material. When an ultrasonic transducer with such a configuration is used underwater, the synthetic resin member acts as a perfect acoustic matching layer between the piezoelectric ceramic and water, resulting in a broadband horizontally omnidirectional ultrasonic transducer. That's it.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 and 3.

FIG. 1 is a configuration diagram showing an embodiment of an ultrasonic transducer according to the present invention. In FIG. 1, a cylindrical piezoelectric ceramic 6
is a flange 8a, with spacers 7a and γb interposed therebetween.
8b, and a cylindrical synthetic resin member 9 is provided on the outer periphery. Further, a cable 10 as a signal line is connected to the piezoelectric ceramic 6, and the piezoelectric ceramic 6 is fixed to the flanges 8a and 8b with bolts 11. As shown in FIG. 1, their peripheries are covered with a molding material 12 such as rubber.

The synthetic resin member 9 has a thickness of about 1/4 = 3-wavelength of the underwater sound wave length, and its material has an acoustic impedance 2 larger than the acoustic impedance zL of water, and the acoustic impedance zO of the piezoelectric ceramic 6. smaller than That is, if the acoustic impedance Z is the geometric mean Eτ of the acoustic impedances Zo and zL, perfect matching between the piezoelectric ceramic and the water is achieved, resulting in a broadband frequency characteristic.

FIG. 3 is a diagram showing the transmission sensitivity frequency characteristics of one embodiment of the present invention compared with the conventional example shown in FIG. 2, where the curved line B shows the conventional example and the curve B shows the present embodiment.

As can be seen from FIG. 3, in this example, the synthetic resin member 9 acts as an acoustic matching layer, and unlike the conventional example, the transmitting sensitivity does not peak in the resonant frequency region, resulting in broadband frequency characteristics. Recognize.

Incidentally, even if the acoustic impedance 2 of the synthetic resin member 9 is not equal to i, if it is larger than the acoustic impedance zL and smaller than the acoustic impedance Zo, the conventional example has a wide band. In this embodiment, the cylindrical piezoelectric ceramic 6 and the synthetic resin member 9 are used, but it is also possible to use an annular piezoelectric ceramic and a synthetic resin member, and moreover, two or more synthetic resin members may be provided. . Furthermore, although this example describes a rubber mold type ultrasonic transducer,
It can also be applied to ultrasonic transducers that make piezoelectric ceramics watertight inside oil-filled boots.

〔Effect of the invention〕

As described above, according to the ultrasonic transducer according to the present invention,
At least one cylindrical or annular synthetic resin member with a thickness of approximately 1/4 wavelength of the underwater sound wave length is provided around the outer periphery of the piezoelectric ceramic, and the synthetic resin member is acoustically matched by applying watertight treatment. It is effective as a layer, and can provide a broadband, horizontally omnidirectional ultrasonic transducer. Therefore, since the present invention is broadband and non-directional in the horizontal direction,
It has the effect of allowing broadband signals such as short pulses to be transmitted and received faithfully and regardless of direction.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of a conventional example, and FIG. 3 is a diagram showing transmit sensitivity frequency characteristics. 6... Piezoelectric ceramic 7a, 7b... Spacer 8a. 8b・Flange 9...Synthetic resin member 10...Cable 11...Bolt 12...Mold material patent Applicant Oki Electric Industry Co., Ltd. agent Patent attorney Takashi Kanakura Nia - Engraving of the drawing (in the content) (No changes) 11. Figure 11, 2. Configuration diagram of this embodiment 11. Engraving of the drawing (no change in content) 2. Diagram showing the frequency characteristics of frequency transmission and reception sensitivity 3. National procedure amendment ( ) Test) 1985 I131128 r+ Director General of the Patent Office Michibe Uga 1, Indication of the case 1985 Patent Application No. 293276 2, Title of the invention Ultrasonic transducer 3, Relationship with the amended person case Patent Applicant address No. 12 Roar, 1-chome Toranomon, Minato-ku, Tokyo Name (029) Oki Electric Industry Co., Ltd. Representative Shigeka Hashimoto Male 4, Agent 7 Contents of amendment Procedural amendment (voluntary) October 1988 June 22nd, Commissioner of the Japan Patent Office Kuro B] Akio 1, Indication of the case 1985 Patent Application No. 293276 2, Title of the invention Ultrasonic transducer 3, Relationship with the person making the amendment f'1 Patent application Representative Shigeo Hashimoto 4, Agent 1 Amend "in Figure 3" to "in Figure 2" on page 4, line 8 of the specification. 2. Change "acoustic matching layer and function" in the fourth line of page 4 of the specification to "
It acts as an acoustic matching layer. 3 Amend Figure 2 as shown in the attached sheet. Configuration diagram of conventional example - Figure 2

Claims (1)

[Scope of Claims] 1. An ultrasonic transducer made of a cylindrical or annular piezoelectric ceramic subjected to watertight treatment so as to be usable underwater, including a cylindrical or annular piezoelectric ceramic whose thickness is approximately 1/4 wavelength of the underwater acoustic wave length. An ultrasonic transducer characterized in that at least one ring-shaped synthetic resin member is provided on the outer periphery of a piezoelectric ceramic and subjected to watertight treatment.