JPS5851691A - Diaphragm supporting method for submarine transmitter - Google Patents

Abstract

PURPOSE:To attain low frequency drive without increased diaphragm diameter, by freely supporting the circumference of the diaphragm with a magnetic fluid and, etc. and extremely decreasing the support stiffness. CONSTITUTION:The circumference of a diaphragm 1 is freely supported with a magnetic fluid 12 filled in a gap of a magnetic circuit consisting of a permanent magnet 11 and a support frame 7. Further, a drive system consists of a magnetic circuit comprising a center pole 4, a permanent magnet 5, and a yoke 6, of a coil bobbin 2 and a voice coil 3 wound on the bobbin 2. Thus, the support stiffness of the diaphragm can be designed very low, and since no repetitive fatigue of the supporter is given, a long period stability can be obtained, and since the resonance frequency of the drive system can be decreased without increased diaphragm diameter, low frequency drive can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an underwater transmitter for an underwater low-frequency sound source, and particularly to a support method for achieving low stiffness suitable for supporting a diaphragm.

Unlike aerial speakers, in conventional underwater transmitters, water pressure is applied to the surface of the diaphragm, so the diaphragm must be supported firmly and its displacement around the diaphragm must be minimized as much as possible.

In particular, when the water depth was to be varied, the structure shown in Figure 1 was used, and the pressure was balanced by equalizing the internal air pressure. In FIG. 1, the diaphragm 1 is surrounded by a support frame 7.
The device uses a magnetic circuit consisting of a voice coil 3 wound around a coil bobbin 2, a center ball 4, a permanent magnet 5, and a yoke 6 to drive the voice coil and vibrate the diaphragm.
The method is similar to that of electrodynamic speakers, and the inside of the watertight membrane is air.

An object of the present invention is to lower the low-side resonant frequency of an underwater transmitter without enlarging its shape, and to expand its operating frequency range to the low side. To achieve this objective, it is necessary to lower the support stiffness as much as possible. In other words, the periphery of the diaphragm 1 shown in FIG. 1 is fixed to the support frame 7, and even when driven by the voice coil, the periphery does not contribute to the vibration amplitude. By freeing the stiffness, it is possible to reduce co-morbidity.

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 2, the periphery of the diaphragm 1 is freely supported by a magnetic fluid 12, and is supported by a support frame 7.

The magnetic fluid 12 is filled in the gap between the magnetic circuit made up of the permanent magnet 11 and the support frame 7.

On the other hand, the drive system consists of a center pole 4 and a permanent magnet 5° yoke 6.
It consists of a magnetic circuit consisting of a coil bobbin 2 and an alligator-wound voice coil 3.A signal current is passed through the voice coil and the vibration drives a diaphragm, similar to the well-known electrodynamic Nubika. It is.

The supporting magnetic material around the diaphragm 10 is a liquid, and the material does not suffer fatigue damage even after repeated large-amplitude excitation, and if measures are taken to prevent leakage, a stable support system can be realized over a long period of time. For this reason, in the embodiment, the diaphragm is not exposed, but an acoustic window 13 is provided and an acoustic oil 14 is interposed inside the window. Furthermore, the interior of the watertight body 8 was realized as air.

According to the present invention, as described above, the supporting portion of the diaphragm can be designed to be extremely small, and long-term stability can be achieved without repeated fatigue of the supporting portion.

This allows the entire diaphragm to vibrate freely, making it possible to achieve almost ideal pinuton motion.

In this way, it is possible to lower the resonance frequency of the drive system without increasing the diameter of the diaphragm while maintaining a small size, making it possible to lower the frequency, making it possible to provide a small transmitter as an underwater acoustic low-frequency sound source. Ta.

[Brief explanation of the drawing]

Figure 1 shows the internal structure of a conventional underwater transmitter.
FIG. 2 is a longitudinal sectional view showing the internal structure of an underwater transmitter according to an embodiment of the present invention. 1... Vibration plate, 2... Bobbin, 3... Voice coil 4... Center pole, 5... Permanent magnet, 6...
・Yoke, 7... Support frame, 8... Watertight body, 1
1...Permanent magnet, 12...Magnetic fluid, 13...Acoustic window, 14...Acoustic oil agent Susuki 1) Toshiyuki

Claims (1)

[Claims] In an underwater transmitter consisting of a diaphragm, a bobbin, a voice coil, a center ball, a permanent magnet, a yoke, a support frame, and a watertight body, one permanent magnet and a magnetic fluid are provided to support the diaphragm, and the area surrounding the diaphragm is A method for supporting a diaphragm of an underwater transmitter, characterized in that the diaphragm is freely supported and its support stiffness is extremely low, thereby allowing the diaphragm to perform almost ideal piston motion.