GB280424A - Improvements in diaphragms for use in acoustic reproducing devices - Google Patents

Abstract

280,424. Menkens, C. March 28, 1927. Diaphragms; loud-speakers; magnetic instruments.-A conical diaphragm 1 for sound reproducing instruments, such as loud-speakers, is formed with apertures 2 and radial and concentric strengthening ribs 3, 4. The ribs 3 instead of being radial may be arranged in a spiral or other desired form. The diaphragm is formed from thin sheet material, such as aluminium, wood, celluloid, papier-machÚ or cardboard, the cone being covered on one or both sides with thin paper, silk, &c. and subsequently treated with a suitable dope. The diaphragm may be formed by spinning, moulding, or, as shown in Figs. 4 and 5, by first cutting out a flat disc which is pressed by suitable dies into a cone shape, the surplus metal being taken up by folding the sheet on itself on lines radiating from the centre so as to form the radial ribs 7. The periphery of the cone may be of channel formation as at 5, Fig. 2, or may be wrapped round a fine wire or cane 6, Fig. 4. Numerous methods of flexibly mounting the periphery of the diaphragm on a baffle ring 9 in a casing 10, Fig. 6, are described, the apex of the cone being directed either towaards or away from the back of the cabinet, an additional member being, in some cases, secured to the inner edge of the ring 9. In the construction, Fig. 2, a number of radial strips 8 are formed from or attached to the periphery of the cone, the outer ends of the strips being secured as shown to the ring 9. In a modification, the strips 8 are replaced by coiled spring wire members. Fig. 6 shows a construction in which the periphery of the diaphragm is attached to a continuous strip of tape 13 secured to the ring 9. In other constructions, the periphery of the cone is mounted either on the inner edge of the ring 9 or on the additional member secured thereto by means of a flat or frustum-shaped continuous strip of flexible material. In constructions in which the ribs 3 extend to the apex of the cone, similarly ribbed washers 30, 31, Fig. 4, are provided so as to obtain a firm connection between the apex of the cone and its actuating armature. In other constructions, the apex of the cone is flattened or otherwise suitably shaped, various forms of washers being described adapted to co-operate therewith. According to the Provisional Specification the periphery of the diaphragm may be left free.