Patent GB-211183-A (GB)
Abstract: 211,183. Brown, S. G. Oct. 12,1922. Mechanical-relay sound-boxes.-Relates to sound producing or reproducing apparatus of the kind in which a member rubbing upon a relatively moving surface is connected to a soundemitting or transmitting device, pressure between the rubbing member and the moving surface being varied by mechanical vibratory action caused by a telephone receiver, a voiceoperated diaphragm, a gramophone sound box or the like, so that the vibrations of such a controlling device are transmitted and amplified. According to the invention the moving member has a polished surface of glass-hard material such as glass itself or polished steel. The rubber mav have a surface of relatively soft material such as cork. A very thin film of slightly " tacky " material such as resin mav be applied to the polished moving surface. The drawings show a sound-magnifying appliance for a telephone receiver. The receiver F which is mounted on a pivoted frame G, has a preferably resilient pin f attached to its diaphragm or reed, the pin resting upon a pad C which may consist of cork cemented to a thin steel plate. The pad C is ,pressed against the polished surface of a disc B which rotates at a moderate speed. A doubled filament D or the like connects the pad to a sound-emitting diaphragm E mounted on the frame G, a horn H being so arranged as to receive the sound from the diaphragm through a tube g<4>. The frame G, which is pivoted at g, has a counterweight g<1>, which enables the pressure of the pin f on the rubbing pad C to be adjusted. As an alternative, the telephone receiver may be mounted in a rocking frame which is independent of the rubbing member and the diaphragm, so that it may be raised clear of the rubber. In the apparatus shown in Fig. 5, the construction of the frame G and its arrangement with respect to the horn H are modified. The telephone receiver F is in this case mounted in a carrier J which is pivoted at j<1>. By this means, the angle of slope of the pin f may be adjusted and the pin may be inclined either forwardly or backwardly with respect to the rotary movement of the disc B, thus providing for variable amplification. The horn serves as a part of the pivotal support of the frame G, and the balance weight g<1> is so arranged that when the frame G is turned' up, the receiver is held clear of the rotating disc. In a further modification, the rotating member is a cylinder around which passes a flexible strap consisting for example of cork backed with thin steel. One end of the strap is connected to a soundemitting diaphragm, while the other is pressed against the drum bv a pad upon which bears a pin carried by a telephone receiver or the like. The cylinder may be grooved. For increased amplification, devices of the kind described may be connected in cascade, two or more connected rubbers being provided on the same moving surface. The Provisional Specifications refer also to the following modifications. A paper strip or a steel band faced with silk may be used as the rubbing member, and instead of a resinous coating on the rotating surface a film of liquid or of gutta-percha may be employed. The rubber may engage in a wedge-shaped groove in the rotating member. In place of a sound-emitting diaphragm, a microphone may be used for telephonic transmission.