Patent GB-359532-A (GB)
Title: A simplified device for electrically recording gramophone records
IPC: G11B3/36
Filed: 1930-07-22
Abstract: 359,532. Sound-recording apparatus. BAWTREE, A. E., 20, Manor Park Road, Sutton, Surrey. July 22, 1930, No. 22065. [Class 40 (ii).] Relates to electrical recording devices adapted to be moved radially over a gramophone turntable by means of a screw-threaded rod rotatably driven from the turntable, and consists mainly in driving the rod by means of a wheel in frictional engagement with the flat upper surface of the turntable or of a recording blank or of a disc on such blank or on the turntable. The invention also provides automatic stopping and signalling means, and a detachable adjustable support for the recording device. As shown, the screw-threaded rod A is rotatably mounted at the outer end in a block M on a hinge N on a support O, and is fitted at the other end with a vertical wheel C having a rubber tyre C<1> in frictional engagement with the upper surface of the recording blank L near the spindle J<1> of the turntable J. The friction wheel may instead make contact with the blank near its outer edge; a reducing gear is then interposed between the wheel and the screw-threaded rod. The electrical recorder E is slidably mounted on a smooth round rod B arranged parallel with the screw-threaded rod between the block M and another block F carried by the screw-threaded rod. A half-nut or a knife edge D<1> on the recorder E engages with the screwthreaded rod A when the recorder is down on the blank, so that the recorder is fed gradually inwards by the rotation of the screw-threaded rod. At the end of the operation, the recorder E comes against and is lifted by an arm F<1> on the block F, thereby disengaging the knife edge D<1> from the screwthreaded rod ; at the same time a signal may be operated. The recorder may also be lifted by a handle. Other means may be provided for stopping the movement at the end of the recording operation. For example, the screw-thread on the rod A may end in a circular thread of larger diameter which stops transmission of radial movement to the knife edge and recorder and lifts the recorder from the blank, or the recorder may be provided with a brake block adapted to come to bear on the wheel C or on a flange on a disc on the turntable. A brush or air jet may be attached to the recorder for removing the dust liberated in the process of recording. The recorder may when desired be replaced by a reproducer. As described in Specification 359,573, the support O of the recording device is detachably mounted on the gramophone by two or more pins P and sockets T ; the pins P, P are radially adjustable in slots in the support 0 ; and the hinge N is vertically adjustable in slots O<1> in the support O, or the sockets T are adjustable in height by a suitable selection of washers between a foundation plate and a top plate securing the sockets to the gramophone. The record blank may extend to the central spindle or may have a large central hole of say four inches which is occupied on the turntable by a flanged central disc. The blank may be of wax-like material or of metal, celluloid, glass, or ebonite ; and the recording may be made by direct cutting, or by depositing an impression which is afterwards developed, or by scratching a varnish coating and subsequently etching with acid in a known way.