GB723620A - A record changing mechanism for gramophones - Google Patents

Abstract

723,620. Automatic gramophones. HAURI, M. April 20, 1953 [April 18, 1952], No. 10859/53. Class 40 (2). In an automatic gramophone, the tone arm 31' is operatively connected to a cycling control shaft 17 by means of an arm 34 which is mounted on the vertical rotational shaft 32 of the tone arm 31' and is frictionally engaged by cams 21<SP>1</SP>, 21<SP>111</SP> on the said control shaft 17. The mechanism is set in motion manually by clockwise rotation of an arm 48, mounted freely about the same axis as arm 34. The movement of arm 48 starts the driving motor by the engagement of a pin 50 on a cam-disc 51 which is rotated in the direction of arrow I to release a switch 60. At the same time a bar 45 connected to arm 48 is moved longitudinally to engage a flat surface 41' on a shaft 41 which is thereby rotated a small amount so that an arm 44 thereon is moved clockwise and a detent 61 latches with a tongue 64 on an arm 63 mounted on a shaft 65. As the turntable rotates a depending pin 73 moves the arm 44 back to its original position whereby the shaft 65 is rotated a small amount and a pin 66 thereon moves away from a tooth 67 on a cam 68 mounted on the control shaft 17, which thus permitted under the influence of a spring 25 to be rotated in the direction of the arrows in Figs. 2 and 3 until a toothed sector 15 on the shaft 17 engages a worm 3 on the turntable shaft 4 to maintain the rotation of the shaft 17. A cam 22a, Fig. 3, on the shaft 17 causes a shaft 57 carrying the disc 51 to be lowered so that cam surface 22b rotates disc 51 further in the direction of the arrow I until a feeler 59 on shaft 57 abuts the edge of the lowermost record stacked on a centre-post 4'. Simultaneously, the cam 21<SP>1</SP> comes in frictional driving contact for a brief period with arm 34, thus tending to hold the pick-up arm in its outermost position. Following this the head of a screw 69 on cam 68 presses down the end of a lever 9 on a shaft 8 carrying an arm 7 which releases a record from the stack on to the turntable 2. The arm 7 acts on a central rod 6 which serves to longitudinally compress and radially expand a resilient member 11 to retail all but the lowermost record, while at the same time conical 'members 13 are withdrawn to permit the lowermost record to drop. During the descent of the record, the edge of the record comes into contact with the sloping ear 59a of the feeler 59 and thereby moves the cam-disc 51 back to a position depending upon the particular size of the record, whereby a surface 55 or 56 is placed in the path of a pin 34a on arm 34, which is subsequently moved by cam 21<SP>111</SP> to bring the tone-arm 31' over the start of the record. At this stage, a cam 21a allows a rod 35 supporting the pick-up arm 31<SP>1</SP> to be lowered, and at the same time the cam 22a lifts the shaft 57 to raise the cam-disc 51 out of the path of pin 34a, so that the tone-arm 31<SP>1</SP> can follow the record groove. This completes the cycle of operations carried out by the rotation of the control shaft 17, which is now arrested by the pin 66 on shaft 65. As the stylus nears the end of the record a pin 36 on the end of arm 34 engages the end of a slot 38 in a bar 37 and slowly turns shaft 41 by means of a link 40 frictionally coupled to shaft 41. The arm 44 is thereby moved into the path of pin 73 which sets the arm 44 back again at each revolution until the run-off groove is reached. When this occurs the detent latches with the arm 63 and initiates another automatic cycle whereby the tone-arm 31' is lifted bythe cam 21a, swung outwardly by the engagement of cam 21' with the arm 34, and the cycle continued as described above. If no record remains on the stack when a fresh cycle is initiated, the feeler 59 encounters no record during its inward movement and thereby moves the cam-disc 51 to a position in which a surface 52 is placed in the path of the pin 34a on arm 34, so that the tone-arm 31' is prevented from being moved inwardly over the turntable, after which the spindle 58 is rotated to the position shown in Fig. 2 to close switch 60 and stop the motor.