JPH0230637B2 - SUICHUSOHAKI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an underwater transmitter, and more particularly to an underwater transmitter that efficiently transmits low-frequency, wide-band sound waves underwater.

Conventional underwater transmitters have the disadvantage that their electroacoustic properties change significantly due to increases in hydrostatic pressure due to changes in operating depth. There are two possible reasons for this.

The first cause is that the diaphragm of the underwater transmitter is displaced by the hydrostatic pressure applied to the diaphragm, thereby reducing the electroacoustic conversion efficiency. Specifically, in the case of an electrodynamic transmitter, for example, when the position of the diaphragm changes, the voice coil, which is integrated with the diaphragm, is displaced. This makes the magnetic flux in the magnetic circuit air gap ineffective and increases the driving force required to produce the same acoustic output.

The second reason is that the volume of the underwater transmitter cavity changes in response to changes in hydrostatic pressure. Specifically, in an underwater transmitter that uses a bellows method using rubber or the like to adjust the pressure inside the cavity and prevent the displacement of the diaphragm described above, the stiffness of the cavity changes accordingly. That is, as the hydrostatic pressure increases, the cavity volume decreases, and the stiffness of the cavity increases accordingly, causing an increase in the low-frequency resonance frequency and raising the lower limit of the usable frequency. As a result, the electroacoustic conversion efficiency is extremely deteriorated, and the electroacoustic characteristics are significantly changed.

The present invention was developed in view of the drawbacks of the conventional underwater transmitter, and eliminates the above two causes of changes in electroacoustic characteristics, and allows low-frequency, wide-band sound waves to be transmitted even when the operating depth (hydrostatic pressure) changes. The objective is to provide an underwater transmitter that transmits waves efficiently without changing its electroacoustic characteristics.

The underwater transmitter of the present invention includes an electroacoustic transducer containing gas inside the cavity, a pressure regulator that adjusts the pressure of the gas inside the cavity to be equal to the external hydrostatic pressure, and a pressure regulator that adjusts the pressure of the gas inside the cavity to be equal to the external hydrostatic pressure. and a low-pass filter that prevents pressure changes from being transmitted from the electroacoustic transducer to the pressure regulator.

By adopting such a configuration, the pressure inside the cavity of the electroacoustic transducer is always balanced equally with the external hydrostatic pressure without changing the volume of the cavity, so that the static position of the diaphragm is always maintained at the initial setting position. It will be done. Therefore, the above objective can be achieved.

The present invention will be described in more detail below with reference to embodiments shown in the accompanying drawings. As shown in the accompanying drawings, the electroacoustic transducer 1 is provided with a magnetic circuit 11, a drive coil 12 provided in the gap thereof, and a diaphragm 13. An alternating current is applied to the drive coil 12 from an AC power source (not shown), which causes the diaphragm 13 to vibrate and emit sound waves.

The cavity 15 of the electroacoustic transducer 1 is connected to the low-pass filter 2 via a pipe 4,
The low-pass filter 2 is connected to the pressure regulator 3 via a pipe 5. The low-pass filter 2 is a mechanical filter, and by setting the cutoff frequency sufficiently lower than the lowest frequency of the electroacoustic transducer 1, the pressure change in the cavity 15 when the diaphragm 12 vibrates is reduced to This prevents the signal from being transmitted to the regulator 3 side.

In addition, the pressure regulator 3 detects external hydrostatic pressure,
It has a function of always making the pressure inside the pressure regulator 3 equal to the external hydrostatic pressure. As described above, the inside of this pressure regulator 3 is connected to the cavity 1 in the electroacoustic transducer 1 via the pipe 5, the low-pass filter 2, and the pipe 3.
5, the pressure in the cavity 15 is always kept equal to the pressure inside the pressure regulator 3, that is, the external hydrostatic pressure.

Therefore, according to this embodiment, the pressure in the cavity 15 within the electroacoustic transducer 1 is always balanced with the external hydrostatic pressure regardless of the water depth used, and the diaphragm 13 is statically always at the initial setting position. is maintained.
Therefore, the mutual positional relationship between the drive coil 12 and the magnetic gap 14 is always maintained constant, and fluctuations in the electroacoustic conversion rate due to changes in external hydrostatic pressure can be reliably prevented.

Further, the volume of the cavity 15 inside the electroacoustic transducer 1 is always kept constant even if the external hydrostatic pressure (water depth) changes. Therefore, changes in the stiffness of the cavity 15 are small, which makes it possible to reduce changes in the low-frequency resonance frequency.

In addition, as the above-mentioned low-pass filter 2, it is possible to use a pore when the change in external hydrostatic pressure is gradual.

As is clear from the above description, according to the present invention,
It is possible to simultaneously eliminate the two causes of changes in electroacoustic characteristics mentioned above, and unlike conventional underwater transmitters, it is possible to efficiently transmit low-frequency, broadband sound waves without changing the electroacoustic characteristics even if the operating depth changes. An underwater transmitter for transmitting sound waves can be provided.

[Brief explanation of drawings]

The accompanying drawings are explanatory diagrams showing one embodiment of the present invention. 1... Electroacoustic transducer, 2... Low-pass filter, 3...
Pressure regulator, 4, 5...pipe.

Claims (1)

[Claims] 1 An electroacoustic transducer containing gas inside the cavity, a pressure regulator that adjusts the pressure of the gas inside the cavity to be equal to the external hydrostatic pressure, and an electroacoustic transducer that adjusts the pressure change inside the cavity due to the generation of sound waves. and a low-pass filter to prevent transmission from the water to the pressure regulator side.