US1824590A - Diaphragm-equipped acoustic apparatus - Google Patents

Description

Sept. 22, 1931. M. BERNARD 1,824,590

DIAPHRAGM EQUIPPED ACOUST IC APPARATUS Filed June 7. 1929 INVENTOR MARCEL BERNARD ATTORNEY l atented Sept. 22, 1931 I MABCEL BERNARD, PARIS, FRANCE DIAPHRAGM-EQUIPPED ACOUSTIC APPARATUS Application filed June 7, 1929, Serial No. 369,076, and in France June 14, 1928.

This invention relates to sound generating or receiving apparatus such as loudspeakers. More particularly it relates to apparatus of this nature wherein the vibrating diaphragm is of large dimensions.

The object of the invention consists in providing an improved suspending means for such large diaphragms which, among other advantages, furnishes the tensional 1 forces insuring rigidity of the diaphragm and, at the same time, furnishes the elastic forces tendin to restore the diaphragm to its position 0% rest.

The invention will be better understood by reference to the accompanying drawings and the description thereof covering an approved form of the basic idea of the invention. In the drawings,

Figure 1 illustrates diagrammaticall a section through the diaphragm suspen ing' means;

Figure 2 illustrates a force diagram for the suspending means; and

Figure 3 illustrates the spring member shown in Figure 1 which is connected between the diaphragm and the suspending member.

As shown in Figure 1, a tympanum 1 preferably of a conical shape, is provided circumferentially witli'a cylindrical border or edge 2. The border 2 may be provided by giving a suitable shape to the sheet of lamina forming the tympanum or it may be formed from a separate piece of material and attached to the edge of the tympanum in any well known manner as by gluing or cement ing. A spring member 3 is arranged to press upon the inner face of the cylindrical border or rim 2. This spring which, for example, may consist of a lamina of metal, is provided with a suitable curvature so that it may exert an oblique force or effort upon the axis of the tympanum when it is depressed by its insertion under the border or rim of the tympanum.

In Fi ure 2 this oblique force is illustrated at F. %t consists of a radial component f and an axial component f The radial force or component i, contributes to the insurance of rigidity of the diaphragm by its being tensioned, whereas, the axial force or component f, contributes to overcoming the counteraction of the motor or driving element until the tympanum has been restored to its position of equilibrium.

In order to acoustically insulate the tympanum from the spring member 3 a layerof insulating material such as felt, soft rubber, etc. is interposed between these two elements.

In the embodiment illustrated by Figure 1 a band of felt indicated by reference char- 6o, acter 4, is bent back, or crimped about the cylindrical rim 2 of the tympanum.

Thespring members indicated at 3 are provided at intervals along the periphery of the tympanum. No particular spacing is re- 05 quired between the spring-like members and the number used may vary with the size of the tympanum, the material from which the spring members are made and various other structural details. If desired, they may be drawn from one piece of sheet metal conveniently cut or stamped. Figure 3 indicates such an arrangement in which the spring member consists of a rim of metal 5 with a group of four springs. The spring 3 in F igure 1 may be regarded as a out along an axial plane ab in Figure 3.

The metal rim 5 may be secured to a supporting member 6 in any well known manner. The supporting member 6 may consist of a planar wall or surface such as a baflie board or the front of a cabinet, and it is provided with a circular opening of suitable size for the free propagation and issuance of the sounds given off by the tympanum. Any well known form of motor or driving means may be installed so as to be supported in any approved manner, such as by suitably arranged arms, from the supporting member 6.

The notches in the metallic rim 5 or the gaps or openings between the separate springs 3 are preferably covered by means of an elastic or felt band in such a way that they will not impede the operation of the device.

, If desired, the loudspeaker may be formed by arranging two diaphragms in opposition with the peak or apex of the diaphragms arranged so as to be driven or impelled by the same driving means. The diaphragms 100 may be of either the same or of different dimensions. V V V Various other modifications may be made Without departing from the spirit of the in- Vention and itis desired that the present invention be limited only by the scope of the claims. V

I claim 1; Acoustic apparatus comprising a dia-.f phragm, a rim on said diaphragm presenting a cylindrical surface, a'support for the diaphragm, and metallic elements fixed to the support and bearing elastically against the interior face of said cylindrical surface.

2. Acoustic apparatus comprising a diaphrag'm, a rim on said diaphragm presenting a cylindrical surface, a support for said diaphragmand a metallic rim furnished with teeth and fixed to the support, said teeth bear- 'ing-elasti'cally against the inner face of said cylindrical surface.-

3; Acoustic apparatus comprising a-diaphragm, a rim on said diaphragm presenting a cylindrical surface a supporting member, metallic means fixedto the supporting memher and bearing elastically against the inner face of said cylindrical surface, and an elas- V tic sheetinterposed between said surface and the metallic means.

'MARGEL BERNARD,

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