Patent GB-381271-A (GB)
Title: Improvements in or relating to automatic stopping devices for gramophones or the like
IPC: G11B17/02
Filed: 1931-07-30
Abstract: 381,271. Gramophones. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London, BOWEN, A., 38, Bull's Head Lane, Stoke, Coventry, and HORNE, D. S., Yardley Fields, Yardley, Birmingham. July 30, 1931, No. 21779. [Class 40 (ii).] An automatic stopping device for gramophones comprises a lever capable of pivotal and longitudinal movement and adapted to be deflected from a normal position periodically by means actuated from the gramophone motor, a member frictionally engaging the lever and moved in accordance with the movement of the reproducing device to return the lever to its normal position, and means actuated by the said motor for moving the lever longitudinally to operate a switch or apply a brake when, because of the completion of travel of the reproducing device, the lever is not returned to normal position after being deflected. In the construction shown in Fig. 1, the pivoted and longitudinally-movable rod J is adapted to be deflected periodically by the action of the end R of a rod Q which is reciprocated by an eccentric P on the turntable spindle B. The member J is normally returned by the tone arm A through the medium of rods C, D, M and quadrant L, the latter being in frictional engagement with the member J. When the tone arm reaches the end of its traverse, the member J is no longer returned and the end R of the rod Q strikes the tip of the member J and moves it longitudinally, thereby rotating the end V of a lever G into engagement with the rim of the turntable. A thrust is thereby applied to the lever G so as to actuate the switch F. A spring K engages the member J and quadrant L so as to return the member J to normal position, independently of the frictional action of the quadrant, during the first part of the reproduction. A lug G<1> on the lever G is adapted to be engaged by the lever D so as to close the switch F when the reproducer arm is moved outwardly. The end V of the lever G may be adapted to remain in contact with the turntable at the end of playing so as to stop the turntable. If desired, the switch arm Fl may be connected directly to the member J, and the lever G dispensed with. The end R of the rod Q may be mounted on a ratchet wheel which is pivoted on the rod Q and engaged by a pawl S so that the member J is engaged only when the end R arrives at a projecting position. In another construction, the pivoted and longitudinally-movable lever Y, Fig. 2, is normally -deflected by the engagement of a pin Z on an arm mounted on the turntable spindle with one of a pair of pins Y<1>, Y<2>, on the lever Y. The quadrant L, which is mounted on an arm M movable with the pick-up arm A, engages frictionally with the lever Y so as to return the latter to normal position. At the end of playing, the pin Z engages the other pin Y<1> and moves the lever Y to open the switch F, the arm of which is loosely connected at U to the lever Y. An edge M<1> of the arm M engages a pin on the lever Y to close the switch on the return movement of the pick-up arm. A spring K is provided to assist, or replace the action of, the quadrant L in returning the lever Y during the first part of reproduction. A turntable brake may be provided in place of, or as well as, the switch F. In a third form, the pivoted and longitudinally-movable lever Y, Fig. 3, is normally deflected by one of a pair of coaxial cams Z, Z<1> which are driven from the turntable spindle and are disposed between the arms X, X<1> of a fork at the end of the lever Y. A curved wire L, which is loosely pivoted to a member M moved by the pickup arm, frictionally engages the lever Y so as to return it to normal position. When the movement of the pick-up ceases, the projection Z<1> engages the arm X<1> and moves lever Y longitudinally to open the switch F. Return movement of the pick-up closes the switch F by the engagement of an inclined edge M<1> on the arm M with the switch lever. An arm M<2> opens the switch when the pick-up is moved to extreme inner position. A spring K holds the fork arm X<1> out of engagement with the projection Z<1> while a needle is being changed and the pick-up is being placed on the record. The switch F may control the gramophone motor or an associated amplifier.