Patent GB-316162-A (GB)
Title: Improved means for automatically returning the tone arm and stopping a gramophone after playing, also adapted for repeating
IPC: G11B3/095
Filed: 1928-04-19
Abstract: 316,162. Brotman, M. April 19, 1928. Returning tone-arm to starting position; repeating-mechanism ; starting and stopping.-A gramophone tone-arm is automatically returned to the starting position after the playing of a record, by mechanism comprising a spring-influenced bar 13, over which the tone-arm 1 travels, the bar being pivoted at 13<a> and normally held horizontally by a catch 14; a member driven independently of the tone-arm is adapted to operate the catch at the end of the playing of a record, whereupon the pivoted bar is tilted and the tone-arm slides back along it. The slide bar is then automatically drawn down again to the horizontal position. A stop 23 (shown separately in Fig. 3), which may be adjusted in accordance with the size of the record being played, is so arranged that the tonearm is brought to rest after the return movement, in such a position that, when the bar' is again lowered, the sound-box is placed on the starting point of the record and playing recommences. The stop may, however, be moved aside, so that at the end of the return movement the tone-arm can slide off the bar on to a support 2. This support may be so arranged that the weight of the tone-arm and sound-box depresses it, causing it to open a switch 4, Fig. 6, in the circuit of the driving motor, thus stopping the machine. The member for operating the catch 14 comprises a carriage 17 mounted to slide against the action of a spring 20 along a screw 18 which is driven by belt and pulley gearing from the machine motor. The carriage has pivoted to it a part 17a engaging with the screw thread, and slidable along a spring-actuated rod 16 passing through it. The rod 16 is normally held down by a finger on the bar 13, so as to keep the member 17a in engagement with the screw. Interposed between the part 17a and the catch 14 is a plunger consisting of two telescopically adjustable parts 21, 21a mounted in a fixed casing. The part 21a, is adjusted so as to be engaged by the member 17a when the end of the playing of a record is reached; the catch 14 is thus moved so as to free the bar 13 and allow it to be raised by a spring 22. When this occurs, the rod 16 raises the member 17<a> from the screw 18, and the spring 20 returns the carriage 17. At the same time the tone-arm slides back along the bar 13. The bar has a depending book 12, the lower end of which is engaged, when the bar rises, by a pin 11 projecting from a wheel 10. This is normally driven by a spindle 6b through an intervening spring 11<a>, but the wheel 10 is temporarily stopped when the pin 11 engages with the hook 12, until a positive drive is transmitted to the wheel 10 through a pin (not shown) engaging in a slot in the wheel 10, the latter pin being carried by a wheel 7 fast on the spindle 6b. Thereupon the hook 12 is drawn down by the pin 11 and resets the bar 13 in the horizontal position in which it is again held by the catch. The stop 23 comprises a part 23a which can be held upright by a strut 23b, or turned back as shown in dotted lines. A pivoted upper part 23c is set in either of the positions shown, according to the size of record used, to determine the position which the tone-arm reaches in its outward movement.