GB965597A - Improvements in loudspeakers - Google Patents

Abstract

965,597. Loud-speaker diaphragms. GOODMANS INDUSTRIES Ltd. March 7, 1963 [May 29, 1962], No. 20613/62. Heading H4J. A moving coil loud-speaker has a diaphragm cone made wholly or in part of expanded polyethylene. If the cone is wholly of expanded polyethylene it may be supported by an integral peripheral suspension, the latter being bonded to the chassis. The peripheral portion may be radially extended to serve as an airtight resilient gasket for the loud-speaker frame. Alternatively, the expanded polyethylene cone may be covered on each side with a paper layer to form a sandwich construction, in which case the peripheral suspension is formed from one of the paper layers or from the polyethylene. Alternatively, a paper cone is covered on both surfaces by layers of polyethylene which are joined at the edge of the cone, the polyethylene being extended to form the peripheral suspension. In another embodiment a paper cone with integral peripheral suspension has a cone of expanded polyethylene bonded to its front surface. This may be made by resting the paper cone on a similarly shaped but apertured metal support and applying adhesive to the front surface of the paper cone. A flat circular sheet of expanded polyethylene is placed over the front of the cone and clamped all round its edges so that no air can pass between the paper cone and the sheet. Adhesive may be applied to the inside of this sheet as well as or instead of the paper cone. After heating of the sheet, vacuum is applied through the apertures in the support whereby the sheet is drawn into contact with the cone and the two are bonded by the adhesive. Alternatively, the sheet of expanded polyethylene is initially in the form of a disc from which a segment has been cut. It can thus be readily formed into a cone and pressed into contact with the adhesive-covered paper cone.