Patent GB-422818-A (GB)
Title: Improvements in or relating to the mechanical recording of oscillations
IPC: G11B11/00
Filed: 1934-02-02
Abstract: 422,818. Recording sound and the like. PHILIPS-MILLER NAAMLOOZE VENNOOTSCHAP, Emmasingel, Eindhoven, Holland. Feb. 2, 1934, No. 3496. Convention date, Feb. 2, 1933. [Class 40 (ii)] A method of mechanically making a record of sound or like vibrations on a carrier, particularly a film, in a form which is suitable for effecting optical reproduction, consists in using a car - rier provided with one or more groups of ridges or deformable folds extending in the direction of movement of the carrier, and producing by means of a corresponding number of chisels, each having a straight cutting edge and moving to and from the surface of the carrier, the same number of groups of tracks having width variations ; the number and cross-section of the ridges or folds of each group is so chosen that the total width variations of all the tracks of each group are in magnitude an amplification of the corresponding amplitude of movement of the recording tool. The carrier is preferably formed by a transparent base of celluloid or the like, having an opaque covering, e.g. of graphite or paint, an intermediate softer layer of a substance such as gelatine being provided if required. The opaque layer may be omitted, the film in this case being suitably treated after recording, e.g. by blackening the sound track with ink or dye. The ridges or deformable folds are of very small dimensions (e.g. ten protuberances can be formed side by side over a width of 2À5 mm.), and they may be made by means of one or more pairs of rollers or milling cutters between which the film is passed. Fig. 9 shows such a device, comprising rollers 12, 13, which are preferably built up from separate accurately ground discs 15. This tool may be arranged within the recording- apparatus, or it may be used separately so as to produce a film with preformed ridges &c. before the recording operation. Preferably, the protuberances, grooves, or deformable folds are so formed that their surfaces in contact with the recording member form an angle which is at least 3‹, but is preferably about 30‹. Figs. 1A and 1B show a film 1 provided, in accordance with the invention, with three different groups A, B, C of sound tracks, which may be made simultaneously or in succession by means of vibrating chisels M, Fig. 3 ; the tracks in any one group are congruent. When the separate records occupy the appropriate positions in the direction of the length of the film, they may be scanned during reproduction by a single light slit 6. Fig. 5 shows an example of the use of a carrier 1 having deformable folds, the dotted lines showing a position to which the carrier may be depressed by the tool M during recording. It is shown that an advantage of using carriers with protuberances having small apex angles of about 90‹ or less is that the chisel need not cut deeply into the carrier material in order to produce a satisfactory record, so that the depth of the intermediate layer may be lessened and the chisel angle may be made greater than would otherwise be necessary. The invention may be applied to disc or cylindrical records. Specification 422,815 is referred to. The Specification as open to inspection under Sect. 91 states also that a recording member having two or more cutting edges may be used, for example, a chisel built up from several pieces. Chisels having a number of teeth of various forms are described and shown, Figs. 4<a> and 4b (Cancelled) showing examples, in one of which the cutting edges are curved. The protuberances of the carrier may have the forms of the chisel teeth shown in these Figures. Fig. 7 (Cancelled) shows a construction of a carrier with deformable folds, used with a multiple-toothed chisel M<1>. This subject-matter does not appear in the Specification as accepted.