Patent GB-562650-A (GB)
Title: Improvements in or relating to apparatus for playing gramophone records
IPC: G11B17/02
Filed: 1942-11-25
Abstract: 562,650. Automatic gramophones. SHAW, M. N. H., and METCALFE, C. Nov. 25, 1942, No. 16755. [Class 40 (ii)] [Also in Group XXIV] Relates to clutch mechanisms for automatically starting and stopping the record changing and pick-up return operations of magazine gramophones. According to the invention, a " driving " clutch-member continuously driven by the gramophone driving means is normally held disengaged from a " driven " clutch-member by a control member, this control member is displaced to release the " driving " clutch-member to start the automatic cycle of operations, the " driving " clutchmember is then brought into engagement with the " driven " clutch-member by a restoring force, and at the end of the cycle of operations the control member returns to its normal position and in doing so engages the " driving " clutch-member and causes this clutch-member to be moved by the gramophone driving means against the said restoring force out of engagement with the " driven " clutch-member. The invention is shown applied to a magazine gramophone of the kind described in Specification 554,530, in which a pinion 6, Fig. 1, on the turntable spindle 1 is in mesh with a pinion 7 adapted to be clutched to a pinion 9 to transmit motion to a wheel 10 fast with cams which make one revolution to perform the automatic operations of the gramophone. The pinions 7, 9 constitute the driving " and " driven " clutch-members, the engagement between them being by dogs 21. The pinion 7 is urged down into clutching engagement with the pinion 9 by gravity, but is normally held up away from the pinion 9 by the end 25d, Fig. 2, of a lever 25 riding against a lower circular face track 30 on the pinion 7. The lever 25 is pivoted at 26, and another end 25e of this lever is normally in a slot 15 in a disc 14 fast with the cams and wheel 10. When the play of a record is completed, a tap-tap mechanism swings the lever 25 counterclockwise as seen in Fig. 2 thereby releasing the pinion 7 and the disc 14. A spring-urged shutter 50 on the disc 14 immediately closes the slot 15 to prevent the return of the lever 25. The released pinion 7 drops by gravity into clutching engagement with the pinion 9, and motion is transmitted thereby to the wheel 10 to perform the record changing and pick-up return operations. When the revolution of the wheel 10 is completed, the shutter 50, which projects slightly beyond the periphery of the disc 14, is deflected by the end 25e of the lever 25, whereupon the lever 25 is swung back by a spring 29, the end 25e re-enters the slot 15 in the disc 14, the end 25d engages inclined face ramps 20 on the pinion 7, which, being still rotated by the gramophone driving means, is caused to rise away from the pinion 9 and allow the end 25d of the lever to pass inward to the circular face track 30 to hold the pinion 7 up in its normal disengaged position. This sequence of operations is repeated at the end of each record. A stud 86 on the disc 14 co-operates with a switch device to prevent switching off while the automatic operations are proceeding. The outward swing of the lever 25 to release the clutch-member 7 may also be performed by manual operation through a link 27. The tap-tap mechanism is similar to that 'described in Specification 496,764. The inward movement of the pick-up arm during the playing of a record is transmitted to a lever 35 clamped by a screw 63 to a plate 61 fast with the vertical spindle 34 of the pick-up. The lever 35 travels counterclockwise as seen in Fig. 2 during the playing of the record. A pin 35b on this lever first rides in a concentric slot 36 in a lever 37 until it reaches the bent extension 36a of the slot. The lever 37 is then turned clockwise about its pivot 38 and by frictional engagement turns another lever 39 also clockwise about the same pivot 38. A pawl 43 is pivoted at 42 on the lever 39 and the end 43d of this lever is thus moved towards the turntable spindle 1. At each rotation of the turntable, however, a projection 48 on the turntable spindle strikes a buffer 49 on the pawl and pushes the lever 39 back. At the end of the record, the quick-pitch groove of the record causes a quicker approach of the pawl to the turntable spindle 1, and, before the projection 48 can act on the buffer 49, a finger 46 on the turntable spindle strikes the notched end 43d of the pawl 43 and imparts a comparatively large counterclockwise movement to the lever 39, causing a shoulder 40 thereon to bear on a stud 41 on the lever 25 and thereby deflect that lever to release the pinion 7. The pick-up operating mechanism is similar to those described in Specifications 554,554 and 561,891. It includes two levers 65, 66 loosely mounted on the pick-up spindle 34 and adapted to engage opposite sides of a stud 64 on the plate 61 which is fast with the spindle 34. The lever 66 is urged counterclockwise as seen in Fig. 2 by a spring 67 to co-operate with abutting stops 70, 70a according to the diameter of the record to be played; and the lever 65 is controlled by a link 68 from the cams driven by the pinion 10. The link is connected to the cam mechanism by a pin-and-slot connection with a spring adapted to yield when, for example, the pick-up arm is moved by hand irrespective of the automatic controls. Non-automatic operation of the gramophone is permitted by the provision of another lever 55, Fig. 4, which can be set by hand to engage the ramps 20 to disengage the clutch-members. The lever 55 is connected by a link 56 to a plate 77 on the spindle 57 of a setting knob. A stud 79a on a spring-urged pivoted arm 79 locks the plate 77 in either of its positions. An arm 75 adjustably clamped to the plate 77 by a screw 75b serves to lock the lever 66 when the plate 77 is set to the position for non- automatic action. A link 89 connects the lever 55 to a switch device to enable the motor to be switched off as desired when the lever 55 is set for non-automatic action.