Patent GB-411144-A (GB)
Title: Improvements in or relating to the recording and reproducing of sound and like vibrations
IPC: G11B11/00
Filed: 1932-09-26
Abstract: 411,144. Recording sound and the like. MILLER, J. A., 4627, 193rd Street, Flushing, New York, U.S.A. Sept. 26, 1932, No. 26673. Convention date, Sept. 30, 1931. [Class 40 (ii).] Relates to records of sound or like vibrations, capable of optical reproduction, which are mechanically produced on a carrier, preferably a film. According to the invention, such records are of variable width and depth, and the width is always greater than the corresponding depth. In making the record, use is made of a cutting tool which vibrates in a direction substantially normal to the surface of the carrier, and the tool or carrier is so shaped that the width variations in the record, which are a magnified representation of the movements of the recording tool, correspond to the vibrations to be recorded. Alternatively, the tool is fixed and the carrier vibrates relatively thereto, the conditions being otherwise the same. Preferably the recording tool 22 has a V-shaped chisel edge, as shown in Fig. 7, and the carrier comprises a celluloid or like base 37, an opaque coating 38, and an intermediate layer 39 which is softer than the base. The opaque coating may consist of paint, dye, or an exposed and developed photographic emulsion. The layer 39, which preferably has a thickness such that the tool does not reach the harder base 37 when at its maximum depth (and is e.g. of the order of .002 ins.) may consist of gelatin, soap, or wax ; the substance known under the Registered Trade Mark " Cellophane " is also suitable, and if sufficiently thick may be used without a supporting base. Fig. 9 shows in plan the form of a sound track 40 that has been produced by means of a chisel such as is shown in Fig. 7. After the sound has been thus recorded, it may be reproduced from the record immediately, by photo-electric means, without any further treatment of the record, or it may be used as a negative for printing upon a picture film. Instead of a wedge-shaped cutting tool, a chisel having a straight cutting edge 46, Fig. 14, may be used, producing a sound track bounded on one side by a straight line. In another arrangement, a tool similar to a circular saw is used, the cutter being rotated by a motor, and the film vibrated relatively thereto ; in this case the film may be guided through a slit in the vibratory armature of an electromagnet. A further method of carrying out the invention consists in using a film strip having a longitudinal rib R formed along the soft layer and opaque coating, as shown in Fig. 17, in conjunction with a chisel 49 having a flat cutting edge. The vibrations of the tool produce a track having the characteristics above defined. The film, instead of having a preformed longitudinal rib, may be deformed to that shape as it passes around a suitably formed roller at the recording point. A record produced according to the invention may be either of the translucent or of the episcopic kind, and may be made on a blank other than a film, e.g. on a disc which may comprise a base of glass, celluloid, or the like. Fig. 1 shows the general arrangement of parts in a recording machine constructed in accordance with the invention. The film 3 is fed by a motor-driven sprocket wheel 4 round a drum 15 where the sound recording takes place, the chisel acting upon the film at the lowest point of the drum. The chisel (not shown in Fig. 1) is fixed to a reed armature which is surrounded by a coil to which the sound-influenced currents are supplied, the armature being adapted to vibrate between the polepieces of magnets 24. A suction nozzle 17 removes shavings cut from the film. Specification 408,222 is referred to. The Specification as open to inspection under Sect. 91 comprises also the following matter : The record may be made on an entirely transparent carrier, which is subjected to suitable treatment after recording, to produce a difference in transparency between the groove and the surrounding area. A record for episcopic reproduction may be made on a carrier having a reflecting backing, e.g. of metal or of a material embedding silver particles. The production of variable density records is described, using a carrier comprising a celluloid base and a coating of " light damping material " which is cut away to varying depths by the vibrating chisel. The cutting edge of the chisel may be a curve or broken line, and a plurality of chisels or a chisel having more than one V-shaped edge may be used. The drum over which the film passes at the recording point is described in detail. It is provided with teeth engaging a single row of perforations in the film, and with pointed rods 34, Fig. 7 (Cancelled), slidable diametrically through the drum. The rods are pushed down in turn by a roller 36 so that the pins successively penetrate the film where it bridges a recess in the drum. A method of making the records in accordance with the " constant-amplitude " system (which is described in Specification 403,164) is also described. This subject-matter does not appear in the Specification as accepted.