Patent GB-226253-A (GB)
Title: Improvements in and relating to method of and means for production of sonorous vibrations
IPC: G10K9/12
Filed: 1923-07-16
Abstract: 226,253. Severy, M. L. July 16, 1923. Electrically vibrated instruments; combined with pianofortes.-Sounds of notes of desired pitch and predetermined quality are produced by moving, relatively to an electromagnet in operative connection with a body such as a diaphragm or string &c., an armature having a formation artificially produced and corresponding to the desired sound-waves. The armature may be rotary and its necessary peripheral form may be obtained bv dimensional variations either in a radial direction or parallel to its axis, or both. The armature may be built up of laminµ, respectively producing the fundamental note and one or more partials. A number of electromagnets may be connected to one vibratory element such as a soundboard. The character and intensity of the sounds may be varied bv particular bodily movements of the armature relatively to the electromagnet, and the intensity alone by controlling the current or voltage of the electromagnet circuit. The invention is applicable to organs &c., while other instruments and human voices may be simulated, and defective diaphragms which unduly emphasize certain tones may be compensated for. Fig. 1 shows an artificially shaped rotor 24 rotated in front of an electromagnet 20 which is in circuit with a rheostat 23 and push-button or key 22, and whose core 19 is connected to a diaphragm 16 provided with a horn 18. In a modification in which the rheostat is omitted, the rotor is made up of differently formed laminµ, and an electromotor which drives the rotor also operates means moving the rotor backwards and forwards along its shaft, thus continuously modifying the timbre by bringing different laminae nearest the electromagnet. The laminµ may be set in various angular relations, and the fundamental or any partial may be emphasized by duplicating the corresponding lamina. Fig. 5 shows an example of a form of rotor for producing a violin tone. Fig. 6 shows diagrammatically a synthetic tone-producing means in a musical instrument. The resonators A, B, C produce simultaneous sounds jointly under the control of a rheostat 54 and key, each resonator being also individually under the control of a rheostat 51 and switch 52 so that the proportions of the sounds in the combination mav be varied. A synchronizer 56 may be employed to keep constant the relative speeds of the rotor shafts. Instead of using the rheostat 54, the rotors 49 may be moved bodily towards and away from the electromagnets, or vice versa by means such as described in U.S.A. Specification 1,218,324. The invention may be combined with a pianoforte of the kind in which the dampers are withdrawn from the strings by electromagnets energized on depression of the keys as described in U.S.A. Specification 1,183,245. Closure of the key circuits also energizes electromagnets in front of which rotors are rotated, the cores of the electromagnets being secured to the bridge on the soundboard. The pianoforte strings may be omitted. Fig. 8 shows a group of vibratory elements which may be used in an instrument capable of simulating different instruments. The rotor unit of each electromagnet 20b consists of three laminated rotors 74, 75, 76 which produce different effects and are mounted on a driven shaft 67 which is slidable into any one of three positions being held by one of the pins 71 - - 73. In another construction two rotors may act simultaneously on a twin electromagnet having a core of horseshoe form. The armature may be in the form of an endless belt, or a disc with the wave surface on its side face. The electromagnets may be entirely mounted on the vibrating elements. The invention is described as a modification of the method described in U.S.A. Specification 1,098,983 consisting in opening and closing with note-frequency a circuit containing an electromagnet in proximity to a diaphragm, string or the like; and of the method described in U.S.A. Specification 1.190,332 in which the current in the electromagnet circuit was instead rendered pulsatory by the rotation of a shaped rotor in proximity to a metallic member in the circuit.