GB404400A - Improvements in electrically operated sound signals employing vibrating diaphragms - Google Patents

Abstract

404,400. Electric horns. AUSTIN, L. J. F., Lichfield Chambers, Upper Priory, Birmingham. Sept. 7, 1932, No. 24882. [Class 13.] The diaphragm of an electric horn is arranged to vibrate with an amplitude of the order of 0.01 inch and is held around its periphery by a substantially line or narrow ring pressure. In one embodiment, Fig. 1, the diaphragm e is supported on a narrow ledge of the base plate j and held in position by rolling over the periphery of the front cover o. In modifications the periphery of the base plate is rolled over the diaphragm e and the front cover rolled over the base plate, Fig. 4, or the diaphragm is rolled over the base plate, Fig. 5. Alternatively the front cover may be omitted, the diaphragm being turned over the edge of the base plate and spot welded thereto, Fig. 6. In each case the rolling tools are so dimensioned and adjusted as to produce no compression or tension on the diaphragm. The actuating mechanism comprises a base plate j carrying the hollow core a<1> of an electromagnet co-operating with an armature b carried at the centre of a compound spring bridge c. A threaded rod d passing through the armature b and the hollow core a<1> strikes or is attached to the diaphragm e, a nut d<1> locking the rod to the armature and springs. One of the distance pieces k between the springs is provided with bent over prongs k<1> which bridge the stationary contact member f of the contact breaker and engage the movable contact g, a screw f2 being provided to adjust the make- and-break device. The cover m is screwed to a bracket s and according to the Provisional Specification may house a battery and support a push button. Specification 381,227 is referred to.