Communications – electrical: acoustic wave systems and devices – Signal transducers – Underwater type
Patent
1997-05-12
1999-06-15
Eldred, J. Woodrow
Communications, electrical: acoustic wave systems and devices
Signal transducers
Underwater type
367175, 381398, 381399, H04R 2300
Patent
active
059128631
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention involves electro-acoustic transducers. The specific electro-acoustic transducers referred to produce a homogeneous high-power acoustic field from at least two linear sound sources or from a widespread area.
2. Description of the Relevant Art
Electrostatic speakers are known for producing a homogeneous sound field from an area. However, these have only been used to a limited extent. One reason for this is their restricted acoustic power per unit area.
SUMMARY OF THE INVENTION
By means of an elongated, electrically conductive diaphragm within a highly magnetic field, a linear source of sound, giving a high sound energy, is obtained. An least two elongated diaphragms with intermediate and enclosing elongated magnets are in accordance with the invention arranged in such a way that the transverse length of the diaphragms becomes at least the same as the transverse length of the intermediate elongated magnets. The sound from the two diaphragms will in this way merge without considerable interference at a short distance from the sound sources. By positioning several such sound sources side by side, a broad sound source with an area producing an esentially homogeneous acoustic field is acquired.
Such a broad sound source may be adjusted for the entire or part of the audio band of 0-50 kHz, without the requirement of a matching transformer or a crossover filter. This is possible through the diaphragms of conductive materials being electrically connected in series and/or in parallel, making the driving amplifier detect a primarily perfect resistance which may be varied optionally within the range of 2-90 Ohm, for example.
The area of the widespread sound source may be varied within a wide range to obtain the desired directional effect and characteristic. The sound source can accordingly be curved to partly or wholly form, for instance, a cylindric area, with the sound transmitter in the latter case acting as a radially pulsating cylinder for all the frecluences of the audio band, or optional parts thereof.
Further advantageous characteristics are evident from the patent claims and the detailed description of embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows schematically a cross-section of part of a device according to the invention.
FIG. 2 shows an alternative arrangement.
FIG. 3 shows schematically, seen from the front and from one end, a module of a plain unit according to the invention, containing six elongated diaphragms.
FIG. 4 shows a cylindric sound transmitter according to the invention.
FIG. 5 shows schematically an enlarged part of the cylindric area as shown in FIG. 4.
FIG. 6 shows a cross-section of the sound transmitter as shown in FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
One of the designs according to the invention is essentially made up of fundamentally linear and elongated sound sources as shown in cross-section in FIG. 1. A protected, electrically conductive diaphragm 1 is arranged in the gap between two elongated magnet elements 2A and 2B. In addition, similar diaphragms, 1A and 1B, may be arranged in gaps on opposite sides of the magnet elements. The protected magnet elements both have an elongated magnetic pole along one of the long sides of diaphragm 1 and an opposite magnetic pole along the other long side of diaphragm 1. In case electricity flows along the length of the diaphragm (into or out of the horizontal paper) the diaphragm will be influenced by a power across the diaphragm (upwards or downwards) depending on the direction of the current. When running a current of sound frequency, the entire length of the diaphragm functions as a loudspeaker diaphragm.
The magnetic elements 2A and 2B are positioned in protective bodies 3, giving mechanical support to the magnets which are effected by the same cross-power as diaphragm 1 when electricity flows in the diaphragm.
The dimensioning of the diaphragms and the magnetic elements are of imperative significance in order to obtain a high
REFERENCES:
patent: 4837838 (1989-06-01), Thigpen et al.
Cello, Limited
Eldred J. Woodrow
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