Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Electromagnetic
Patent
1996-04-04
1999-08-10
Le, Huyen
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Electromagnetic
381423, 181171, H04R 2500
Patent
active
059370750
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a loudspeaker having a loudspeaker diaphragm centrally connected with the voice coil of the loudspeaker and at its outer rim connected with a resilient edge suspension, through which the diaphragm is fixed to an associated loudspeaker chassis. The edge suspension is made of a suitable rubber resilient material and is shaped as an annular shell member of an almost half circular cross section, prolonged outwardly in a flat ring flange for connection with the loudspeaker chassis and inwardly in a flange portion, which, in case of a conical diaphragm, has the same cone angle as the diaphragm and serving to hold an outer edge area of the diaphragm in being glued thereto.
The edge suspension is moulded with thin, angular transitions between the edges of the arched resilient portion and the two flange portions, whereby a free movability of the diaphragm is secured. The resilient portion will hold the diaphragm in its desired position of rest, and it is clearly advantageous that the diaphragm is easily movable, as this will of course increase its efficiency.
2. Description of Related Art
In connection with the invention, however, it has been recognized that there is an associated drawback, viz. some resonance phenomena resulting from the lacking attenuation of the kinetic energy as represented by the inertia of the oscillating diaphragm. Predominantly, the energy will be transferred back to the voice coil by propagation through the diaphragm material from the different partial areas of the diaphragm, and just hereby the said resonances may occur. Admittedly, the associated hearable distortion is not marked, but in particular for high quality products it is commercially important if there are distortions that are measurable and hearable by qualified listeners.
SUMMARY OF THE INVENTION
The present invention is based on the assumption that the presence of the resonance or interference phenomena are widely due to the fact that the entire diaphragm is influenced in a fully uniform manner, whereby, lengthwise through the diaphragm material, there may occur identically phased dynamic impacts, which--as a sort of wave fronts--may interfere with reflected fronts and thus generate noticeable resonances. On this background it has been considered to introduce some asymmetry or non-uniformity in the diaphragm structure seen in the roundgoing direction, not for weakening the impacts, but rather for producing a certain spreading of the phasing of the forces through the diaphragm, with the aim of reducing the said interferences, which will be reduced noticeably if the said wave fronts do not appear fully uniformly in the radial or axial direction of the diaphragm.
On this background it has been found that a noticeable improvement is obtained already by the modification of introducing, in connection with fully conventional diaphragms and edge suspensions, a differentiation of the degree of the overlapping between the diaphragm flange of the edge suspension and the outer edge portion of the diaphragm. Normally, the diaphragm edge is fully circular, but in connection with the invention it has been found that already by a cutting off of partial portions of the edge of the diaphragm it is possible to achieve a clearly measurable improvement of the loudspeaker characteristic. Already by cutting off two opposed edge portions a measurable improvement has been noticed, but a cutting off of five partial areas has provided for results that make the invention commercially important.
Through experiments it has been found that the primary effect of the invention is due to the edge suspension uttering itself with a differentiated spring effect round along the edge of the diaphragm, more than to the said clippings producing a differentiated mass distribution of the diaphragm material itself in the edge are thereof. In the non-cut areas the diaphragm edge will reinforce the entire flange of the edge suspension, while the corresponding reinforcement will be
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Le Huyen
Safran David S.
Vifa-Speak A/S
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