Created on 09.10.2019 21:16.
Last updated 09.10.2019 21:32.
Author: Pavel Sayk.
The invention relates to the field of electroacoustics, in particular to the formation of acoustic radiation and designs of magnetic systems of electroacoustic transducers.
Thanks to its design, the electro-acoustic transducer has a high efficiency and insignificant nonlinear distortions.
The electroacoustic transducer contains two permanent axially magnetized annular magnets 1, placed between the upper and lower annular flanges 2 and directed towards each other by the same-named poles, between which an annular magnetic multilayer gasket 3 is located, the middle layer 4 of which is made of a paramagnetic or diamagnetic material, and the remaining layers 5 are placed symmetrically relative to the middle layer 4 and are made of soft magnetic anisotropic materials, the non-magnetic gasket 6 adjoins the lower annular flanges 2 and 13, and the voice coil 7, mechanically connected to the membrane 8, installed in the working gap coaxially and symmetrically to the annular magnetic multilayer gaskets 3 and 14, a membrane holder 9 with a cover 10, in the center of which, along the axis, a quasicone 11 is installed, the tip of which enters the central holes along the axis of the central core and membrane holder 9, two annular flanges 13, two annular magnets 12 and an annular, magnetic, multilayer the gasket 14 is placed coaxially, with a working gap to the outer annular magnets 1, two annular magnets 12 are located between the upper and lower annular flanges 13 and are directed towards each other by the same poles, but opposite to the external annular magnets 1.
An annular magnetic multilayer gasket 14 is placed between the magnets 12. The membrane holder 9 is made with a central hole 15 and with radial holes 16 and is mechanically connected to a non-magnetic annular gasket 6 and to the outer edges of the cover 10 and membrane 8.
Layers 5 and 4 of annular, magnetic, multilayer gaskets 3 and 14, at high radiator powers and significant dimensions of the voice coil 7, are optimally, in terms of costs and technology, made toroidal, twisted from a tape made of soft magnetic anisotropic and diamagnetic or paramagnetic materials.
Two acoustic chambers are formed in the transducer. The inner chamber is formed by the inner, emitting surface of the membrane 8, the inner surface of the cover 10, the surface of the quasicone 11, the tip of which enters the hole of the central core and the central hole 15 of the membrane holder 9, which is the outlet of the acoustic chamber. The acoustic radiation of the chamber is directed towards the center, through the central hole 15.
The outer chamber is formed by the outer emitting surface of the membrane 8, the inner surface of the membrane holder 9 and the surface of the magnetic system. The radial holes 16 are the outlet of the acoustic chamber. The acoustic radiation of the chamber is directed from the center through the radial opening 16.
The electroacoustic transducer works as follows. When an electroacoustic signal is applied to the voice coil 7, its electromagnetic field interacts with the magnetic fluxes of the magnetic system, which consists of permanent annular magnets 1 and 12, magnetic flanges 2 and 13 and multilayer magnetic spacers 3 and 14. Coil 7 performs longitudinal oscillations in the working gap, in a magnetic field created by two coaxially placed magnetic systems, depending on the direction of the electric current.
When the coil 7 moves to the end of one of the poles of the magnets 1, 12, it enters the scattered magnetic field and decelerates, since the main magnetic field formed by the magnetic spacers 3 and 14 is directed in the other direction. The working stroke of the coil 7 and membrane 8 is calculated in such a way that the coil 7, at the maximum amplitude of movements, does not reach the ends of magnets 1 and 12. Due to the open acoustic chambers, membrane 8 is symmetrically suspended and loaded, and the magnetic system limits the output in the area of nonlinear distortion of acoustic radiation.
The proposed design makes it possible to significantly increase the efficiency and at high powers of acoustic radiation, up to 0.3 kW of acoustic power, to provide insignificant nonlinear distortions.
Patent: RU 2 140 727 C1