GB291116A - Improvements in electromechanical vibrators - Google Patents

Abstract

291,116. Ateliers J. Carpentier, (Assignees of Nandillon, A. E. G., and Cottet, A. E.). May 28, 1927, [Convention date]. Magnetic instruments; loud-speakers. - An electromagnetic vibrator for receiving or emitting acoustic energy comprises two masses F, M, Fig. 5, connected by an elastic plate E, so that the mass M in vibrating varies the depth of an airgap which is surrounded by the coil Z. The masses may be ribbed for the sake of rigidity. The plate E has thickened extremities E<1>, E', with machined inner surfaces which are fixed by screws or otherwise to the masses F, M. The coil Z is wound on a bobbin Z<1>, Fig. 4, made of cellulose acetate or other insulator and fastened to the fixed pole-piece I by a rivet R of cellulose acetate or the like. The air gap N can be adjusted by means of a set-screw G, the polepiece I being separated from the flange J by a saw-cut T. The masses F, M may form a permanent magnet or, as shown in Fig. 8, there may be two parallel air gaps N, N', the coil or coils being mounted in recesses H so that the magnetic circuit is restricted to the pole-pieces I, I<1>. The coil may carry d.c. and a.c. components of current, or there may be a separate winding for each component. The movements of the jaw M may be damped by means of a container A, Fig. 5, filled with metal filings or other granular material and having a rigid plate for its upper face and a diaphragm carrying an adjustably positioned loading-mass for its lower face. The vibrator may be attached by a stud B to a fixed support or it may be connected rigidly or by elastic coupling to another vibrator, a diaphragm (Fig. 9, not shown), or a sounding board a, Fig. 10. The vibrator may be used for transferring energy from an electric circuit to a liquid, gaseous or solid medium or vice versa. It may be tuned, or may be so highly damped as to transmit speech and music. The masses and elastic member may be formed of a single piece of metal if desired. An oscillographic record may be obtained by means of a stylus attached to the moving mass.