Acoustics – Diaphragm – Mounting or suspension means
Reexamination Certificate
2002-10-10
2004-04-27
Nappi, Robert (Department: 2837)
Acoustics
Diaphragm
Mounting or suspension means
C181S171000
Reexamination Certificate
active
06725967
ABSTRACT:
FIELD OF THE INVENTION
This invention is related to a loudspeaker cone suspension geometry for reducing non-linear distortion in loudspeakers.
BACKGROUND OF THE INVENTION
The construction and operation of an electro-dynamic loudspeaker is well known in the art. It is well known that such loudspeakers exhibit non-linear distortion for various reasons, including: the displacement dependent compliance of cone suspensions and displacement dependent motor parameters, such as force factor “Bl” or voice coil inductance. The inventor has discovered that shape of a cone suspension contributes to distortion in the output of the loudspeaker.
There is a need for a speaker cone suspension (surround) which is capable of reducing non-linear distortion, particularly in low frequency, high power sub-woofers having large cone displacements.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides a cone suspension with a semi-elliptical cross-section. The cone suspension creates less distortion in the sound produced by the loudspeaker in response to an audio signal that is used to displace the loudspeaker's speaker cone.
In additional embodiment, cone suspensions with paraboloic and triangular cross-sections are provided.
In another embodiment, one or more rib elements is added to the cone suspension to decrease its rigidity thereby reducing the formation of wrinkles in the suspension when the speaker cone is displaced. Such wrinkles contribute to distortion in the output of the loudspeaker and reducing them correspondingly reduces the distortion. Such rib elements may be provided on a cone suspension with a semi-circular, semi-elliptical, triangular or semi-parabolic cross section, or with another shape.
An object of an aspect of the present invention is to provide an improved loudspeaker.
In accordance with this aspect of the present invention, there is provided a loudspeaker comprising a housing; a speaker cone for displacing a volume of air; and, a cone suspension mounting the speaker cone to the housing. The cone suspension has an inner periphery supporting the speaker cone, an outer periphery mounted to the housing, and, a resilient central portion extending between the inner periphery and the outer periphery. In cross section, the resilient central portion is separated from a base plane extending between the inner periphery and the outer periphery, and has a central apex spaced from the inner periphery and the outer periphery and spaced from the base plane by a selected height. The inner periphery and the outer periphery are separated by a selected width. The selected height is substantially greater than ½ of the selected width.
An object of a second aspect of the present invention is to provide an improved a cone suspension for a loudspeaker.
In accordance with this second aspect of the present invention, there is provided a cone suspension for mounting a speaker cone to a housing. The cone suspension has an inner periphery supporting the speaker cone, an outer periphery mounted to the housing, and a resilient central portion extending between the inner periphery and the outer periphery. In cross section, the resilient central portion is separated from a base plane extending between the inner periphery and the outer periphery, and has a central apex spaced from the inner periphery and the outer periphery and spaced from the base plane by a selected height. The inner periphery and the outer periphery are separated by a selected width. The selected height is substantially greater than ½ of the selected width.
Further aspects of the present invention are illustrated and described in the following description and the attached drawings.
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patent: 6449375 (2002-09-01), Hutt
Wolfgang Klippel, Nonlinear Large-Signal Behavior of Electrodynamic Loudspeakers at Low Frequencies, J. Audio Eng. Soc., Jun. 1992, 483-496, vol. 40.
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Wolfgang Klippel, The Mirror Filter—A New Basis for Reducing Nonlinear Distortion and Equalizing Response in Woofer Systems, J. Audio Eng. Soc., Sep. 1992, 675-691, vol. 40.
P.G.L. Mills and M.O.J. Hawksford, Distortion Reduction in Moving-Coil Loudspeaker Systems Using Current-Drive Technology, J. Audio Eng. Soc., Mar. 1989, 129-148, vol. 37.
Johan Suykens, Joos Vandewalle and Johan Van Ginderdeuren, Feedback Linearization of Nonlinear Distortion in Electrodynamic Loudspeakers, J. Audio Eng. Soc., Sep. 1995, 690-694, vol. 43.
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Audio Products International Corp.
Bereskin & Parr
Nappi Robert
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