Patent GB-682647-A (GB)
Title: Improvements in or relating to a record player
IPC: G11B17/02
Filed: 1950-12-11
Abstract: 682,647. Automatic gramophones. LINCOLN ENGINEERING CO. Dec. 11, 1950 [Jan. 7, 1950], No. 30226/50. Class 40 (ii). In a record player for playing both sides of a record, the turntable is mounted on a cradle which is swung into one or other of two oppositely facing positions and the movements of the pick-up arm controlled by a spring-biased sliding member, which is manually moved in one direction and latched against the biasing means while one side of the record is being played, and is automatically released at the end of the record so as to slide in the other direction and cause the other side of the record to be played. Records are individually held by a clamp 61, Fig. 5, on to a turntable 45 which is small enough to expose both sides of a record. The turntable is mounted on a shaft 47 in a bearing 49 supported by a V- shaped cradle 19 pivoted about an axis A passing through the plane of a record held on the turntable 45. The shaft 47 is rotated by means of a large friction disc 51 thereon which is coupled to a driven shaft 217 by a jockey pulley 235; mounted on the cradle 19, and by a pulley 233 when the cradle is in the lower position, and by a pulley 229 when the cradle is in the upper position. The shaft 217 is driven by a disc 216, Fig. 3, thereon by frictional engagement with a motor shaft 213. The cradle is swung from one position to fhe other by means of a pinion 95 and rack 99, which is located by pins 101, Fig. 4, on a deck 1. The rack 99 is pushed to and fro by .projections 115, 117 on a sliding plate 113, the distance between the projections 115, 117 being such that there is an element of lost motion. between the plate 113 and the rack 99. The plate 113, which is' provided with cam surfaces controlling the pickup arm movements, is biased. by a spring 119 to the right, as viewed in Fig. 4, and is manually movable to a left hand initial position before'a record is played, by means of a grip 169, Fig. 3, in which, position it is held by a catch 135, Fig. 11, forming one limb of a spring- loaded armature 127 of an electro-magnet 123. In this position, the cradle 19 is in the lower position. Rapid movement of the plate 113 to the right when the catch 135 is released is pre-. vented by a dash-pot 141 mounted beneath the plate. 1. After a record has been clamped upon the turntable, the motor is started by the pressure of a button 411, Fig. 13, on a spring-loaded rod 407 which closes contact arms 399, 397 of a switch 401 mounted on a bar 403 pivotally supported at one end at a fixed point 393. The other end rests on plate 113, or in its absence, deck 1. The contact arms 399, 397 are locked in engagement by the tooth 421 of a catch 417 pivoted at a point 419 on switch 401. The pick-up, which is mounted on an arm 253, Figs. 6 and 10, pivotally mounted on a pin 269 in the upper end 255 of a rod 257 freely rotatable in a bearing tube 111 is then placed manually on the record. A coiled tension spring 271 fixed to a bracket 272 mounted on the rod 257 reduces pressure of the stylus on the record. When the stylus reaches the run-off groove of the record an arm 259 mounted on the lower end of the rod 257 closes a switch 381 in the circuit of the electro-magnet 123, so that the armature 127 is tripped, the catch 135 is released, and the plate 113 is free to commence its movement to the right, as viewed in Fig. 11. During initial movement of the plate 113 the beginning of a ramp 283 thereon, Fig. 6, lifts the pick-up from the record by means of a rod 273. Further movement brings a leading part 319, Fig. 7, of a cam surface 313 on the plate 113 into contact with a cam-follower 311 mounted on an arm 307, pivoted at 295, which engages a downwardly projecting rod 291 screwed into the boss 255 at the top of the pick-up arm supporting rod 257, whereby.the pick-up arm is swung clear of the record. Further movement brings the tongue 115 of the plate 113 into contact with the rack 99 to move it to the right, as viewed in Fig. 11, so that the turntable cradle 19 is rotated counter clockwise to its inverted position where it tends to be held against a stop pin 43, Fig. 3, by the over-centre action of a spring 185. In the lower position, the cradle 19 registers with the stop pin 39. While the cam-follower 311 is still in contact with the straight part 317 of cam 313, a cam-follower 339, on a lever- 335 coupled to a hooked lever 329 by a spring 341, is also moved by the part 319. Both of the levers 335 and 329 are movable about a vertical post 295, and the latter lever 329 is connected' by a spring 331 to an arm 375 supported at one end at a pivotal point 373 and held against one of three adjustable stop screws 355, 357 or 359 by a spring 377. The stop screws 355, 357, 359 are mounted at the lower end of a shaft 361 controlled by an indicating knob 364, Fig. 3, which is manually set according to the diameter of the record to be played. As the cam-follower 339 follows the surface 319 of cam 313 along to surface 317, the spring 341 becomes tensed and draws lever 329 into contact with a downwardly projecting rod 293' in the pick-up arm boss 255. During the period in which both of the cam-followers 311 and 339 are on the surface 317 no rotation of the boss 255 is effected by the lever 329 because pin 291 is still held back by lever 307, but as cam-follower 311 descends the surface 321 the lever 329 becomes effective in rotating the boss 255 so that the pick-up arm is moved inwardly towards the record until an arm 351 of lever 329 engages one of the stop screws 355, 357, 359 according to the diameter of the record. During the last part of the movement of plate 113 the rod descends the end of ramp 283 so that the pick-up is lowered onto the start of the record. During the earlier part of the movement of plate 113 the bar 403, carrying the motor switch 401, has dropped from the end of plate 113 on to deck 1, but the switch remains latched by catch 417 because it is mounted on the switch 401 itself and moves therewith. When the stylus is lowered onto the second side of the record it is free again to traverse the record and does so until the switch 381 is again closed by the arm 259. The resulting movement of the armature 127 lifts the catch 135 which trips the catch 417 of the motor switch 401 and thereby stops the motor. To' play another record the plate 113 is re-cocked manually by means of the grip 169. During this movement the pick-up is swung by the cam-surface 321 to its extreme position and the turntable cradle 19 returned clockwise by the rack 99 and pinion 95 to the lower position ready for the replacement of the record on the turntable.