JPS60196100A - Electromechanical transducer for low frequency - Google Patents

Abstract

PURPOSE:To obtain a small and light-weight electromechanical transducer for low frequency which has high resistance to hydraulic pressure, by producing a coil-shaped oscillator with an electrostrictive material that produces distortions according to the voltage impressed. CONSTITUTION:An electrostrictive material is used to produce a coil-shaped oscillator 1, and upper and lower end parts of the oscillator 1 are fixed by fittings 2 as shown in the figure. The oscillator 1 produces a so-called lateral electrostrictive effect where the vibrating direction is orthogonal to the field direction of the electrostrictive material. Therefore the oscillator 1 produces distortions in its lengthwise direction when electric signals are impressed to the oscillator 1 via lead wires 3a and 3b. Then the oscillator 1 produces mechanical vibrations in its circumferential direction. Thus the mechanical resonance is produced with a frequency that causes a standing wave of a half wave over the entire coil length of the oscillator 1. The both ends of the oscillator 1 are fixed with fittings 2 and therefore the vibrations are damped. Then the circumferential vibrations of the oscillator 1 are converted into the vibrations of the radius direction. Thus a sound wave of a resonance frequency can be radiated in the radius direction. A wave echo sounder transducer device is obtained by covering the outer surface of the oscillator 1 by the rubber molding, etc. and has excellent underwater resistance to hydraulic pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a 7L air-mechanical transducer used in an electroacoustic transducer that converts electrical vibrations into mechanical vibrations to generate vibrations in water, and particularly relates to a The present invention relates to a low frequency electromechanical converter used as a frequency resonant transmitter.

BACKGROUND ART Conventionally, low-frequency electromechanical transducers have been of the vJ type, which can obtain low-frequency resonance using a flexible mechanical vibration system, or of the electrostrictive type, which uses a bent plate. L or 1
~ The above-mentioned conventional transducer has a disadvantage of poor water pressure resistance because the mechanical vibration system is flexible. Also, cylindrical!
! The electromechanical transducer for low frequency using Shimitsuku vibration is
Although it has relatively excellent water pressure resistance, it has the disadvantage that its outer diameter increases inversely with frequency due to its high longitudinal elastic constant in the circumferential direction, making it large and heavy at low resonance frequencies.

OBJECTS OF THE INVENTION It is an object of the present invention to solve the conventional drawbacks mentioned above and to provide a low-frequency electromechanical converter that is small, lightweight, and has good water pressure resistance.

Structure of the Invention The low-frequency electromechanical transducer of the present invention has a coil-shaped vibrating body formed of an electrostrictive material that generates strain according to an applied voltage, and both ends of the coil-shaped vibrating body are connected with metal fittings. It is characterized by being fixed by.

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

FIG. 1(A) is a front view showing a first embodiment of the present invention, FIG. 1(B) is a plan view thereof, and FIG. 1(C) is a front view of the first embodiment of the present invention.
It is an A sectional view. That is, the coiled vibrating body 1 is constructed by forming an electrostrictive material into a coiled shape, and the upper and lower ends of the coiled vibrating body 1 in the figure are fixed by metal fittings 2. Metal fitting 2 is the second
As shown in the figure, a substantially circular upper and lower fixing part 2 with a stepped part
a.

2b is fixed by a substantially cylindrical connecting part 2c, and the tip of the coiled vibrating body l is fixed to the step part of the fixing parts 2a and 2b by brazing or the like.

Electrodes are attached to the inner and outer surfaces of the coiled vibrating body 1, respectively, and lead wires 3a and 3b are connected to each electrode. The coiled vibrating body 1 uses a so-called lateral electrostrictive effect in which the electric field direction of the electrostrictive material and the vibration direction are perpendicular to each other.

Therefore, when an electric signal is applied from the lead wires 3a and 3b, the coiled vibrating body 1 generates strain in its length direction, and mechanical vibration occurs along the circumferential direction.

Then, the coiled vibrating body 1 mechanically resonates at a frequency at which a half-wavelength standing wave is generated over the entire length of the coil. Both ends of the coiled vibrating body 1 are fixed by metal fittings 2, and vibrations are damped. Thereby, the circumferential vibration of the coiled vibrating body 1 is converted into radial vibration. Therefore, it is possible to radiate sound waves at the resonant frequency in the radial direction. If the outer surface is covered with a rubber mold or the like and used as a transducer and used underwater, it has excellent water pressure resistance.

FIG. 3 is a perspective view showing a second embodiment of the invention.

In this case, in order to use the electrostrictive effect in the vertical direction, coiled vibrating body 4 made of electrostrictive material is provided with coiled electrodes 5 at equal intervals, and the electrodes 5 are connected alternately. Connect to lead wires 3c and 3d. Since the electrostrictive effect in the vertical direction has a higher electromechanical conversion ratio than the electrostrictive effect in the horizontal direction, an efficient electromechanical converter for low frequencies can be obtained. The water pressure resistance is as good as in the above example.

FIG. 4 is a perspective view showing a third embodiment of the present invention.

In this case, the coiled vibrating body 6 made of an elastic material includes a plurality of sets of electrostrictive material 7a, an extraction electrode 8, and an electrostrictive material 7a.
b are planted at equal intervals. A plurality of extraction electrodes 8 are connected to a lead wire 3e, and an electric signal is applied between the lead wire 3e and a lead wire 3f provided at the end of the coiled vibrating body 6. In this case, the speed of sound inside the coiled vibrating body 6 can be changed by selecting the elastic material of the coiled vibrating body 6, so there is an advantage that the resonance frequency can be adjusted. It is possible to compensate depending on the material. It also has the advantage of being easy to process.

In each of the embodiments described above, the number of turns of the coiled vibrating body can be set arbitrarily, and the larger the number of turns, the lower the resonance frequency can be. The resonance condition for a coiled vibrator is that its total length is equal to half a wavelength of vibration, so a cylindrical vibrator with the same outer diameter (the resonance condition is that its circumference is equal to one wavelength of vibration) ), the resonant frequency can be lowered in inverse proportion to twice the number of turns. Therefore, a low frequency electromechanical converter can be provided in a small size.

In each of the above embodiments, both ends of the coiled vibrating body and the metal fitting 2 are connected and fixed by soldering, adhesive or mechanical, but since the metal fitting 2 is not a rigid body, the vibration of the coiled vibrating body is , is somewhat influenced by the braking ability of the metal fitting 2. This effect can be eliminated by embedding an electrostrictive material in the metal fitting 2 and causing the metal fitting 2 itself to vibrate torsionally in a direction that damps both ends of the coiled vibrating body.

Effects of the Invention As described above, in the present invention, since both ends of the coiled vibrating body are fixed with metal fittings, low frequency vibrations corresponding to the length of the coiled vibrating body are converted into radial vibrations. can be converted to . Therefore, it is possible to provide a small and lightweight electromechanical converter for low frequencies with high water pressure resistance.

[Brief explanation of the drawing]

FIG. 1(A) is a front view showing the first embodiment of the present invention, FIG. 1(B) is a plan view, FIG. 1(C) is a sectional view taken along line A-A, and FIG. FIG. 3 is a perspective view showing a second embodiment of the present invention, and FIG. 4 is a perspective view showing a third embodiment of the present invention. In the figure, l: coiled vibrating body, 2: metal fittings, 3a to 3
f: Riet wire, 4: coiled vibrator, 5: electrode, 6: coiled vibrator made of elastic material, 7a, 7b: electrostrictive material,
8: Extraction electrode. Applicant: NEC Co., Ltd. Agent Patent Attorney: Toshisuke Sumita 1 Figure 22 Figure 3 gl 4 Figure

Claims (1)

[Claims] A coiled vibrating body is formed of an electrostrictive material that generates strain in response to the applied force H, and the coiled vibrating body has lI+4
A low frequency electromechanical converter characterized by having its ends fixed with metal fittings.