GB434895A - Improvements in or relating to the mechanical production of oscillation tracks, particularly sound tracks on carriers - Google Patents

Abstract

434,895. Recording sound &c. PHILIPSMILLER NAAMLOOZE VENNOOTSCHAP, Emmasingel, Eindhoven, Holland. June 1, 1934, No. 16403. Convention date, June 2, 1933. [Class 40 (ii)] A method of recording sound or like vibrations on a carrier, as a track having depth variations and corresponding variations of width, is characterized by the use of a flexible or resilient guide or runway, having a resonance in the upper part of the frequency zone to be recorded, and adapted to be deformed by the recording member in such manner that the angle between the cutting edge thereof and the carrier varies in accordance with the position occupied by the cutting member. By this means, compensation for the asymmetrical influence of the resistance of the material is obtained. Use is preferably made of a film comprising- a transparent base, a softer transparent intermediate layer, and an opaque outer coating. The device shown in Fig. 6 comprises a conveyer roller 21 over which the carrier film 22 runs, the roller being toothed at one side. At the part where the record is to be produced by the vibratory chisel 23, the roller has formed in it a circumferential recess 24, bridged by a cylinder 25. The size and material of the cylinder (which is made of a resilient substance such as ivory, celluloid, or spring steel) are such that during recording the cylinder wall becomes deformed under the influence of the chisel movements, so that the angle between the cutting edge and the film surface varies in accordance with the amplitudes of movement of the chisel. This effect is shown diagrammatically in Fig. 11, in which the lines I, II and III indicate three positions of the V-shaped chisel (II showing the zero position), while 29, 30, 31 represent the corresponding positions taken by the opaque covering layer of the film. The natural frequency of oscillation is preferably about 5000 cycles per sec. Instead of making the part 25 of the roller of resilient material such as those specified above, the whole roller may be made of such material. In applying the invention, the soft intermediate layer of the carrier may be thinner, and consequently the chisel angle greater, than usual. Two modifications are described, Figs. 8 and 9 (not shown), in which the roller comprises two flanged parts clamped together with their flanges opposed to form an annular gap below the recording tool; the flanges are so constructed as to have the required natural high frequency. As another alternative, a curved stationary runway formed by two separated tongues may be used.