Acoustic device and method for making same
An acoustic device and operating frequency technology, applied in the direction of diaphragm structure, planar diaphragm, etc., can solve the problems of insufficient frequency response and not so effective
Active Publication Date: 2011-09-21
NEW TRANSDUCERS LTD
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However, this distributed mode may not be as effective at the lower bending frequencies where the modes are sparse, and is usually not sufficient for the desired frequency response
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[0185] Figure 1a and 1b The loudspeaker shown comprises: a diaphragm in the form of a circular flat panel 10; and a transducer 12 having a voice coil 26 mounted on the flat panel 10 in a concentric manner. Three annular (or annular) masses 20, 22, 24 are mounted concentrically on the plate 10 using adhesive tape. The voice coil and mass are each located in annular positions called positions 1 to 4, with position 1 being the innermost position and position 4 being the outermost.
[0186] The panel and transducer are supported on a circular chassis 14 including flanges 16 to which the panel 10 is attached by circular suspensions 18 . Flange 16 is spaced from and surrounds the perimeter of panel 10 , and suspension 18 is attached at a ring spaced from the perimeter of panel 10 . In this way, the edge of the plate is free to move, which is important because there are antinodes at this location. Likewise, there is no mass at the center of the plate, since there is also an antin...
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An acoustic device comprising a diaphragm (10) having an area and having an operating frequency range and the diaphragm (10) being such that it has resonant modes in the operating frequency range, an electro-mechanical transducer having a drive part coupled to the diaphragm (10) and adapted to exchange energy with the diaphragm, and at least one mechanical impedance means (20, 22, 24) coupled to or integral with the diaphragm, the positioning and mass of the drive part (26) of the transducer and of the at least one mechanical impedance means (20, 22, 24) being such that the net transverse modal velocity over the area of the diaphragm (10) tends to zero. A method of making an acoustic device having a diaphragm having an area and having an operating frequency range which includes the piston-to-modal transition, comprising choosing the diaphragm parameters such that it has resonant modes in the operating frequency range, coupling a drive part of an electro-mechanical transducer to the diaphragm to exchange energy with the diaphragm, adding at least one mechanical impedance means to the diaphragm, and selecting the positioning and mass of the drive part of the transducer and the positioning and parameters of the at least one mechanical impedance means so that the net transverse modal velocity over the area tends to zero.
Description
technical field [0001] The present invention relates to acoustic devices, such as loudspeakers and microphones, and more particularly to bending wave devices. Background technique [0002] In principle, a point force applied to a pistonic speaker diaphragm will provide a naturally flat frequency response, but a power response that falls on the higher frequencies. This is due to the fact that radiation coupling changes as the wavelength of the radiation becomes comparable to the length l of the diaphragm or half the diameter or radius of a circular diaphragm, i.e. where ka is greater than 2 or kl is greater than 4 (k is the wavenumber frequency). However, for a theoretical, free-standing bending-wave panel loudspeaker, pure force (ie, a massless point drive) will provide flat sound pressure and flat sound power over frequency. [0003] However, actual bending wave slabs are supported on suspensions and have exciters with complex driving point impedance including mass. Such ...
Claims
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IPC IPC(8): H04R7/04H04R7/10
Inventor 格雷厄姆·班克尼尔·哈里斯
Owner NEW TRANSDUCERS LTD