Patent GB-544546-A (GB)
Title: Improvements in and relating to devices for automatically controlling the movements of a pick-up arm in talking machines provided with means for changing discs automatically
IPC: G11B17/16
Filed: 1940-05-06
Abstract: 544,546. Magazine gramophones. BLAKE, W. H. (Paillard & Cie Soc. Anon., E.). May 6, 1940, No. 8087. [A Specification was laid open to inspection under Sect. 91 of the Acts, Nov. 11, 1940.] [Class 40 (ii)] Relates to magazine gramophones of the kind in which record discs of two diameters can be dropped one at a time from a pile to the turntable, and a feeler disposed below the pile is deflected by a disc of large diameter falling on the turntable to cause the pick-up to be correctly re-positioned on the record according to its size. According to the invention, the re-positioning device includes a fork 88, Fig. 3, having wedge-shaped prongs 96, slidable between a fixed plate 97 and a slidable plate 98, Fig. 2, urged up by springs 101, whereby a pin 38 carried by the plate 98 is adapted to co-operate with a cam 36 or 36a, Fig. 1, according to the position of the fork 88 which is controlled by the feeler 102, Fig. 3. The limbs 96 of the fork 88 embrace and are guided by the rod 48 which serves to lift and lower the pick-up arm. The shank of the fork is guided by a groove 95 embracing a fixed pin 94. A short transverse groove 87 on the fork is engaged by a pin 86 on a lever 84 co-operating with a pawl 90, which is pivoted at 93 and biassed by a spring 92. The feeler 102 is an upright lever pivoted at its lower end on an horizontal axis in such a position that it is clear of a 25 cm. record but is deflected by a 30 cm. record. The feeler is formed with a lug 103 bearing against the end of the pawl 90. When records of 25 cm. are being played, the parts are in the position shown in Fig. 3. The thick ends of the wedged-shaped prongs 96 are then between the plates 97, 98 with the result that the pin 38 projects downwards sufficiently to co-operate with the cam 36, Fig. 1. When a 30 cm. record is dropped on the turntable, the feeler 102 is deflected and deflects the pawl 90 thereby releasing the lever 84. A spring 85 then turns the lever 84 anti-clockwise and moves the fork 88 to the right. Thin parts of the wedge-shaped prongs 96 then come between the plates 97, 98 and the pin 38 rises out of reach by the cam 36 and into co-operative action with the cam 36a, which gives a smaller inward swing to the pick-up arm to correspond to the 30 cm. diameter of the' record. If the fork has thus been set to the right by the feed of a 30 cm. record to the turntable, then at the next record changing operation it is returned to the left by the co-operation of the cam 81, Fig. 1, with the lever 82 which is fast with the lever 84 on the pivot 83. The pawl 90 then again holds the lever 84 and therefore the fork 88 in the position shown so long as a 30 cm. record is not fed to the turntable. Parts of the record changing mechanism are also shown in Fig. 3. The spindle 35, which carries the various controlling cams as shown in Fig. 1, also carries a disc 54 with an eccentric pin 55 thereon in engagement with a groove 55<SP>1</SP> in a lever 56 pivoted at 56<SP>1</SP>. The end of this lever is formed with a slot 57<SP>1</SP> opening into a wide loop 56a. During automatic record changing operation, the slot 57<SP>1</SP> is in engagement as shown in Fig. 3 with a pin 57 on a rod 58 connected to a bell-crank lever 59 pivoted at 62. Only one bell-crank lever is shown, but there are several of them inter-connected in well-known manner to control the release of the records. The automatic record changing operation may be suspended by deflecting the rod 58 to remove the pin 57 from the slot 57<SP>1</SP>. This is performed by turning a handle 109 from the full-time position O to the dotted-line position R. For this purpose, a lever 63 is fitted on the spindle 110 of the handle and has a pin 63<SP>1</SP> in engagement tumbler-switch fashion with a slot 63<SP>11</SP> in the rod 58. Another lever 108 on the spindle 110 is connected by a pivot to a rod 107 guided by a bracket 106 and influenced by a spring 107<SP>1</SP>. When the handle 109 is turned to the position R, the lever 107 is thrust forward to lock the fork 88 in its set position. If the record on the turntable is a 25 cm. record, and the fork 88 therefore in the left position, Fig. 3, the end of the rod 107 comes on the right of a pin 105 on the fork and prevents any displacement of the fork to the right. If the record is a 30 cm. record and the fork therefore in the right position, the end of the rod 107 passes to the left of the pin 105 between that pin and the end 112 of the pawl 90, and again the fork mechanism is locked in position. This ensures the correct positioning of the pick-up according to the diameter of the record on the turntable, the playing of which is to be repeated. The handle device is also arranged to permit the changing of a record before the playing is completed. For this purpose, the handle 109 is moved from position O to position C. A pin 113 on a lever 108 fast with the spindle 40 of the handle then bears on a lug 68<SP>1</SP> on a rod 68 and draws that rod to the right thereby releasing the end 71 of a lever 16, which initiates the record changing and pickup return operation as described in Specification 544,545. The handle is returned from position C to position O by spring action when released by the hand.