Patent GB-315737-A (GB)
Title: Improvements relating to gramophones
IPC: G11B3/46
Filed: 1928-04-17
Abstract: 315,737. Hall & Co., Ltd., W., and King, G. B. April 17, 1928. Needle-changing mechanism. - Needles are supplied automatically from a magazine to a quick-release needle-holder of the sound-box when the tone-arm is moved outwards after playing, and provision is made to allow a released used needle to fall from the holder and to support a fresh needle supplied until the gripper device holds it. The needle magazine may be detachably secured to a fixed part of the machine or may be carried by an arm movable about the tone-arm mounting and' with the tone-arm during the latter part of its return movement. Provision is made for correctly positioning the soundbox in relation to the magazine to permit the released needle to fall away. In an arrangement employing a stationary magazine the counterweighted tone-arm 2, Fig. 3, has a joint 6, 7, and a projection 147 carrying a roll 48 to engage a slot in a fixed guide 50, whereby the soundbox 1 is suitably positioned when moved against the magazine 54, Fig. 6. In this movement, the needle-gripping device 17, Fig. 19, is moved to release the needle by nose-ended pivoted levers 30, 31 carried by the sound-box coming against rolls 41 and the needle falls from the triangular socket 15 through a shoot 92 which is subsequently closed by a sliding plate 94 serving to support a fresh needle until the gripper can act on the return movement. The fresh needle is supplied from the magazine 54 by a plunger 62, Fig. 6, which is depressed by energy stored up by the return movement of the tone-arm, such movement acting through an arm 51, Fig. 3, and bevel-ended bar 120 to rock a counterweighted lever 114 connected by a pivoted lever 111 to a sliding frame 99, 100, 101 whose cross-bar 101 has a spring blade adapted to engage a notch in the head 63 of the plunger 62 whereby the return of the counterweighted lever depresses the plunger. The sliding shoot-cover 94 is actuated by a cam bar 107 on the sliding frame 99, 100. The needle magazine, which is constructed to be charged with needles inserted singly at the front end, comprises a frame 57, Figs. 16 and 17, and a cover 58 enclosing a needle space and a spring- pressed slider 75 in front of which the needles are inserted through a slot 81<a> and forced past a hook-ended spring-pressed pivoted lever 87 by depression of a spring-pressed slider 78. The magazine has a keyhole slot detachable connection with its support. In a modified arrangement, the needle magazine is mounted on an arm adapted to move about the tone-arm mounting and, as shown in Fig. 27, this arm 186 is moved with the tone-arm during the latter part of its outward movement during which the various parts are actuated by cams. In the arrangement shown in which the tone-arm has a joint 189, the sound-box 190 is capable of limited rotation on the part 188 and is partially turned to bring the needle socket substantially vertical by a lug 199 thereon coming against a spring-pressed plate mounted on the arm 186. The movement of the arm 186 with the tone-arm effects a movement of the needle-supporting plate 229 by the fixed cam 205 so that the needle can fall when released by the gripper through the action of the pivoted levers 228, actuated by sliding member 211, 213 through Bowden wire mechanism 220 from a fixed cam 225. The plunger of the magazine is actuated by a fixed cam 227 engaging a plunger retarding lever 226. Specification 315,903 is referred to.