Patent GB-857571-A (GB)
Title: Improvements relating to record changing phonographs
IPC: G11B17/16
Filed: 1956-01-09
Abstract: 857,571. Automatic gramophones. HANSEN, H. C. Jan. 9, 1957 [Jan. 9, 1956; July 31, 1956], Nos. 697/56 and 23606/56. Class 40 (2). In a record player of the kind described in Specifications 801,174 and 805,963 in which a feeler member on the pick-up arm detects the size of the next record to be played and initially sets the pick-up arm with respect to a cam follower whereby the stylus is ultimately set down at the required radius, means are provided to stabilize at least the lowest record supported on the centre spindle in a predetermined plane. The centre spindle, Fig. 15, which is detachable, is provided with spring-loaded primary supports 328 to support the stack of records and a secondary support member 350 having prongs 354 terminated by knives 362 which are forced outwardly as a centre rod 324 is drawn downwardly during a record-changing cycle to clamp the lowermost record temporarily on the primary supports 328 whereby the record which has been tested falls to the turntable. In the first embodiment a feeler member 151a, Fig. 1, on the pick-up 151 is brought into contact with the edge of the lowermost record under the influence of path 191, Fig. 7, on a cam disc 180 which feeds the pick-up inwardly while held in an extra high position during this part of the cycle by means of a centre cam track on the disc 180 acting on a roller 147, Fig. 13, and lever 145. The cam follower arm 231 is only frictionally coupled to the pick-up arm, so that contact of feeler 151a with the record edge causes the pick-up arm to be set relative to arm 231 such that after the pick-up arm has been taken outwardly by path 193 and then fed in again by path 194 at slightly lower level, the pick-up comes to rest, and is lowered at the correct radius according to the diameter of the record which has in the meantime been released while the cam follower 136 passes from path 193 to 194. As the cam follower 136 enters path 193, the pick-up arm is swung outwardly and at some point in its travel therein, according to the size of the record which has been detected, an abutment 222, Fig. 8, rigid with the tone arm, engages a post 175b and causes the cam follower 136 to ride up over the bevelled edge of path 193 and drop down into path 194, at point 196 of which the pick-up is lowered to the record. In the event of there having been no record left on the centre post during the detecting operation, the cam follower 136 will have followed the outer track 195, and the pick-up when lowered sits on a switch 161, Fig. 1, to stop the machine. The various components of the mechanism, i.e. the turntable bearing 182, the pick-up arm bearing 267, the tap-tap lever 210 which initiates the automatic cycle by causing a slight initial rotation of the cam disc, Fig. 8, as already described in the above-mentioned Specifications, the cam disc 180, the lever 400 which operates the record drop release, and the lever 145, Fig. 13, which controls the vertical movements of the pick-up arm, are all mounted on a bridge member 170 to form a unitary sub-assembly, largely of standardised parts, in which different types of cam disc may be fitted according to the requirements of any particular model of machine. Specifications 757,303, 757,378, 757,379, 770,544, 845,182, 852,061 and 852,062 also are referred to.