GB294508A - Improvements in or relating to musical instruments - Google Patents

Abstract

294,508. Ye¾, A. O. T. April 14, 1927. Electrically vibrated instrument.s.-A musical instrument comprises keys or the like controlling shutters or lamps 11 in front of openings 4 in a fixed opaque screen 3, and means such as a rotating screen 1 bearing arnular zones of opaque and transparent portions for regularly varying, at the appropriate frequency, the intensity of the beams of light which are converged by cylindrical lenses 12, each beam being allowed to fall on a photoelectric device such as a selenium cell 13 in a current-carrying circuit which contains or is coupled to a circuit which contains a telephone 17, loud-speaker, or the like. The boundary between the opaque and transparent parts of a zone may be a sine curve or a curve determining " timbre." The current variation produced may be amplified by thermionic or other means 16. Where a key controls a shutter, the extent of opening, and therefore also the loudness of the note, may depend on the extent to which the key is depressed against the action of a spring; while loudness as a whole may be similarly controlled by movement of the screen 3. A common loudspeaker may serve for all or a number of notes. The number of cells and lamps required may be reduced by the use of parabolic reflectors or refracting prisms. A zone on a screen may be prepared photographically by reciprocating a shutter 30 over a slot 29 in front of a sensitized disc 27 which is simultaneously rotated. Another form of zone is indicated in Fig. 9, the shutter 30 in this case being moved in a direction at right angles to that shown in Fig. 8 and consisting of a strip which is of graduated transparency as regards the direction of movement. Series of screens representing different harmonics may be used with variable electrical resistances to produce any desired timbre. Tremolo effects may be produced by reciprocation of the cells, or by a periodic variation in the brilliancy of the light. The screen 1 may be in strip, cylinder, or cone, form. The wave form of a zone may be obtained from an actual note by coupling the shutter 30 to a stylus engaging a gramophone record of the note. Reference has been directed by the Comptroller to Specifications 10363/88, [Class 40, Electric telegraphs &c.]; 247,629, [Class 40 (ii), Phonographs &c.]; 254,437 and 286,768.