Patent GB-145804-A (GB)
Title: Method and apparatus for recording and reproducing sounds or the human voice
IPC: G11B9/00
Filed: 1920-07-02
Abstract: 145,804. Ghilowsky, C. Jan. 6, 1919, [Convention date]. No Patent granted (Sealing fee not paid). Machines in which records are formed by variably stretching hot wires; electric and magnetic machines; pneumatic machines; records; diaphragms.-Sound-records are formed by allowing the vibra.tions to apply a variable tensile stress to a moving wire which is rendered ductile by heat as it moves past a particular point. The thickness of the wire is thus varied, and sound may be reproduced therefrom by electrical, pneumatic, or mechanical means. Fig. 1 shows a form of the recording-apparatus, in which the wire a is unwound by a reel e from a drum b, its tension being varied by a pulley h carried on a spring i and connected to a sound-receiving diaphragm l. The wire passes through boxes c, d separated by an insulating partition f and containing liquid metal. The boxes c, d are connected to a source of current m, the circuit being completed through the metal and through the wire a, where it passes through an orifice in the partition f. The current heats and softens the wire at this point, and its section is variably contracted by the variable tension applied at the pulley h. After passing the orifice the wire is cooled by the liquid metal. The upper opening g in the box d may be made tight. and the liquid metal kept under pressure applied through a pipe p, vessel n and tube o. In the form shown in Fig. 3, the walls of the boxes r are thicker and less liquid metal is employed, the whole being suthcieutly small to be carried directly by the diaphragm s. The vibrations of the diaphragm vary the point at which the wire is heated. The wire may be of nickel steel, aluminium, magnalium or like alloys, its diameter may vary from a few hundredths to a few tenths of a millimetre, and its speed about ten centimetres per second, and it may be rendered stronger and more flexible by treatment after recording. The liquid metal employed in the boxes c, d may be a fusible alloy which does not attack the metal used for the wire, or lead, bismuth, sodium or potassium. The central part of the partition f<1> may be detachable and in two parts formed of diamond, corundum &c. In reproducing, the wire passes through an aperture in a plate f<1>, Fig. 5, and allows a variable quantity of gas under pressure to escape into the horn y from the chamber w. Alternatively, the wire may pass through a chamber w<1>, Fig. 6, containing liquid under pressure behind a diaphragm l<1>. The passage of the wire through the aperture f<1> produces variations in pressure in the chamber which affect the diaphragm. A telephonic reproducer shown in Fig. 7 comprises a two-part chamber similar to the recorder a, telephone g being placed in a battery circuit connected to opposite ends of the chamber. The wire may also operate the diaphragm mechanically either by passing beneath a stylus connected by a lever to the diaphragm, or by passing through an aperture in a plate b<2> secured to its centre, as shown in Fig. 9. In another modification, the wire passes between the free edges of two vibratory plates set at an obtuse angle to each other.