Patent GB-207374-A (GB)
Title: Improvements in and relating to sound reproducing mechanism
IPC: G11B3/46
Filed: 1922-07-20
Abstract: 207,374. Mitchell, F. B. July 20, 1922. Tools for reproducing ; tool-arms; tone-arm joints; supporting tone-arm and sound-box when out of use.-Relates to sound-reproducing machines of the kind in which a fine wire stylus is used in the sound-box. According to the invention, the wire is released and fed forward automatically, to compensate for wear, either bv gripping or turning the sound-box or moving a part thereon, or by placing the sound-box on a rest, a stop being provided to limit the extent of protrusion of the wire. In the construction shown in Fig. 1, the wire B is gripped by a spring- pressed lever F<30> on the stylus-bar. At the side of the turntable is a support X<1> on which the sound-box rests when not in use. On placing the sound-box on the support after a record' has been played, the stylus-holder C first makes contact with a, part A<42> of a gauge which is mounted by a spring A<43> under the member X<1>. The lever F<30> then bears on the edge X of the support, and is moved so as to release the wire, which falls down to the surface A<41> of the gauge. A stop P is provided to limit the outward movement of the tone-arm and sound-box when placing the latter on the support. In a modification, the gauge is pressed upwards by a helical spring, and the part with which the stylus-holder contacts is an adjustable screw. Figs. 4 and 5 show another construction in which the sound-box is connected by a bayonet joint to an enlargement J" on the end of the tone-arm, and the wire stylus is released and set by rotating the sound'- box on its axis. The wire-holder C<40> is secured in the ordinary needle-socket, and comprises an arm F<40> which, when the sound-box is rotated, strikes a projection J<21> carried by the tone-arm, whereby the wire is released. At the same time, a gauge arm, not shown, is moved by a pinion and rack A<42>, J<22>, so as to lie below the stylus, which, when released, is pressed down by a spring G against the gauge. The sound-box may be connected by a wire or the like to a suitable part of the machine so that rotation of the soundbox is effected by lifting the tone-arm. Various constructions are described in which the wire is released and a gauge brought into position by pressing a hand-lever mounted on the sound-box. In one of these devices, the lever has rack-teeth gearing with teeth on the gauge member. In the construction shown in Figs. 9 and 12, a lever J pivoted in a groove on the edge of the soundbox casing, is adapted to be pressed in so as to operate a spring -controlled gauge-stop A through an intermediate lever X and also to engage a gripping-lever F, to free the wire. In a further modification embodying a lever which is operable by hand or by the weight of the sound-box when the latter is placed on a rest, a gauge-stop is mounted between two springs, one fixed to the lever and the other to an extension of the soundbox casing. A pin on the lever actuates the wire-gripping member. Several different forms of wire-holders, for use with various combinations of releasing and gauging members, are described. Sound-boxes constructed in accordance with the invention may be adapted to work on the underside of a record, in which case the wire stylus, when released, may be pulled up by a magnet. The Provisional Specification states that the stylus-wires " may have supporting covers."