Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Having electrostatic element
Patent
1991-06-04
1993-05-18
Ng, Jin F.
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Having electrostatic element
381201, 381203, H04R 2500
Patent
active
052127354
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to electroacoustical transducers and, more particularly, to wide-ribbon loudspeakers.
BACKGROUND ART
Known in the art are ribbon loudspeakers comprising permanent magnets, sound-reproducing ribbons made of an electrically conductive material and disposed in the working gaps between the poles or pole pieces of permanent magnets (U.S. Pat. No. 4,319,096).
High sound reproduction fidelity is provided by ribbon loudspeakers, in which the permanent magnets are arranged along an open loop, forming an open magnetic system. In devices of this type the most natural, noise-free operating mode of the sound-reproducing ribbons is attained due to the fact that rearward radiation is not shielded and each ribbon operates independently. These devices are disadvantageous in that the active element of the sound-reproducing ribbon occupies an insignificant part of the loudspeaker area. Another disadvantage is a small width of the employed sound-reproducing ribbons, which is due to a short uniform magnetic field between the poles of the magnets, and it presents a severe problem in obtaining the desired low-frequency sound intensity.
Known in the art is a ribbon loudspeaker (U.S. Pat. No. 4,027,111), selected as a prior art device comprising permanent magnets, forming an open magnetic system, sound-reproducing ribbons made, for example, in the form of corrugated members of an electrically conductive material, each of which is located in the working gap between the poles of the adjacent permanent magnets. The length of the magnets in this device is equal to 60-70 mm, while the working gap width is 7-10 mm. Thus the total area of the sound ribbons is equal to only 5-12% of the total area of the device. The remaining area is occupied by passive, non-sound-radiating side faces of the permanent magnets, which affects the loudspeaker. Still another disadvantage of the prior art device is a low sound pressure in the low-frequency audio range due to the small width of the sound ribbons, hence the poor-quality of sound reproduction.
DISCLOSURE THE INVENTION
An object of the present invention is to provide a wide-band loudspeaker, in which a broader audio-frequency band, higher sound-reproduction quality and greater loudspeaker area, involved into active sound reproduction, will be attained.
This object is attained due to the fact that in the wide-ribbon loudspeaker comprising a permanent magnet with a sound-reproducing ribbon, according to the invention, the permanent magnet comprises an internal chamber accommodating a sound ribbon in a plane parallel to the magnet axis, and side walls of the magnet, which are opposite to the ribbon surface, have sound apertures communicating with the internal chamber of the magnet.
The magnet internal chamber accommodating a sound ribbon considerably improves sound reproduction and increases the active sound-reproducing area of the loudspeaker.
According to the invention, the permanent magnet can be made in the form of an integral construction.
To ensure better sound reproduction, the loudspeaker comprises several permanent magnets with internal-chamber forming an open magnetic system, and the sound ribbon is accommodated in the internal chamber of the magnet and between the unlike poles of the adjacent magnets.
In the proposed loudspeaker, the side walls of the magnet can be assembled of magnetic rods parallely arranged and having their magnetic axes of the same direction, and rows are formed on the ribbon surface side, and in the row the rods are spaced by intervals which function as sound apertures, the rod poles being interconnected by fastening plates of a soft magnetic or nonmagnetic material.
According to the invention, the side walls of the magnet may be also assembled of plates, arranged on the ribbon surface side, and these plates should have apertures to permit sound to pass.
The rods or plates of the loudspeaker are of variable cross-section, which provides for higher uniformity of the magnetic field in the internal chamber of the magne
REFERENCES:
patent: 3564163 (1971-02-01), Hobrough
patent: 3939312 (1976-02-01), McKay
patent: 4027111 (1977-05-01), Kasatkin et al.
patent: 4317966 (1982-03-01), Lister
patent: 4319096 (1982-03-01), Winey
patent: 4337379 (1982-06-01), Nakaya
patent: 5021613 (1991-06-01), Garcia
Feldman Ilya A.
Kasatkin Alexei F.
Le Huyen D.
Ng Jin F.
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