Patent GB-407952-A (GB)
Title: Improvements in or relating to arrangements for automatically controlling the playing of gramophone records
IPC: G11B17/02
Filed: 1932-06-20
Abstract: 407,952. Magazine gramophones. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, and JACOBY, H. C. E., c/o General Electric Co., Witton, Birmingham. June 20,1932, No. 17069. [Class 40 (ii).] In a machine in which a stack of records is supported above the turntable at a number of points around its periphery by members given a rotary movement to release the lowermost record, each supporting member comprises a plate 12 .. 14 which normally supports the stack and a knife-like member 15 .. 17 loosely mounted on the plate and located by means of a dome-like projection on the one engaging an aperture in the other so that if, when the supporting plate is withdrawn, the knife-member engages the edge of the lowest record, relative rotation takes place between the knife member and the plate and owing to the wedge action of the projection on the aperture the knife member is raised until it finds the space above the record. In the machine described the supporting members are double-ended to enable them to be used with two sizes of record. Adjustment of the initial position of the record supports also adjusts the mechanism controlling the tone arm which is thus set to an appropriate starting position. The record-changing and tone-arm-adjusting mechanism is driven by the ordinary motor which normally has an adjustable choke in its circuit this choke being shunted while the motor is driving the record-changing &c. apparatus to increase its power. Also it is arranged as far as possible that when one cam surface is doing work the follower of another is tending to drive the cam. Specification 374,908 is referred to. Record feeding arrangements. The record supporting members 12 .. 14 are eccentrically mounted on spindles 50 .. 52 geared together by chain and sprocket mechanism and are adjusted by means of a handle 18 on one of them to an "unload" position or to one of two positions 180‹ apart for playing 10" and 12" records respectively. When the machine is first switched on and after the playing of each record a surface 92 on a cam 93 (shown developed in Fig. 6) rocks a lever 89, Fig. 3, linked to a pair of sectors 77, 78 embracing one of the sprocket wheels and coupled to its shaft 52 by a lever carrying a roller 82, Fig. 7, which, according to the size of record being played, is in one or other of the troughs formed between spade shaped portions and the main part of a flat member 76 secured to the shaft 52. By this means the supports are first (A .. B) turned slightly clockwise to withdraw the knife members and drop the stack on to the plates 12 .. 14, then (B .. C) counterclockwise to insert the knife members between the lowest and the next record and drop the lowest record on to the turntable and finally (C .. H) clockwise to withdraw the knife members and drop the stack on to the plates 12 .. 14. Tone-arm controlling arrangements. The cam surface 94 controls a lever 120, Fig. 5, coupled by means of a pin and slot connection with a crank 122 connected to the tone arm supporting member 23. Lever 120 is also connected to the member 23 by a spring 125. During the initial movement of the cam (A .. D) the pin moves idly in the slot. The tone-arm is then swung inwardly (D .. F). The extent of this movement is limited, when 12" records are being used, by the engagement of a set screw 120<a>, Fig. 4, on lever 120 with a half-sleeve 128 secured to the spindle 52 of one of the record supporting sets. The exact position of the tone arm is determined by the engagement of a pin 31 on a shaft 28 mounted in the tone arm wall with one or other of two flag-like members 38, 39, Fig. 11. These, in the " unload position " are spring-held against stops formed on a guide plate 35. In the playing positions, however, one or other of the flaglike members is turned 90‹ to an inoperative position by a pin 45 (or 46) on a bar 47 which is turned about its pivot, when the setting handle 18 is adjusted, by a pin 54 carried by one of the sprocket wheels and engaging an elliptical slot in the bar 47. When the tone arm is in position, a third cam surface 95 allows a bar 103 to swing about its pivot lowering the tone arm which has been held up hitherto by a rod 29 which engages a bar 27 within the tone arm, into the playing position. During this movement the pin 31 moves in the guide slot 36 or 37 but when the rod 29 moves clear of the bar 27 the latter is able to swing about its pivot allowing the spring 34 to rotate the shaft 28 (an arm on which is engaged by the bar 27) and withdraw the pin 31. During the playing of the record the cam is stationary. When it revolves again the tone arm is raised (K .. M) and swung back to its initial position (L .. N). Power controlling arrangements. Movement of the knob 153, Fig. 2, on the pin 152, Fig. 3, to the " on " position causes the member 150 to move a member 157 clear of a screw 96 on the cam and to move a sliding member 135 to a position in which an insulated contact member bridges springs 142, 143 to switch on the motor. The slide remains latched against its restoring spring by a leaf spring 139. At the same time, a pin 134, Fig. 2, on member 135 frees a lever 133 to allow the driven part 97 of a clutch to engage the driving part 131 and so couple the motor to the cam shaft. When the tone arm is lowered to the playing position, contact springs 107 break the short-circuit across the choke n the motor circuit and a pin on the clutch half 97 rides upon a shoulder provided on a lever 190, Figs. 2, 3, to disengage the clutch. This action is assisted by the lever 89 following the surface 92 which at this moment (H, Fig. 6) tends to drive the cam. Towards the end of the travel of the tone arm, a member 160, Fig. 2, engages a pivoted member 164 connected by a spring 169 to a member 163 pivoted about the same axis and having a projecting portion of its edge engaged by a roller 200 on a pivoted lever 198. Both members are moved together by the tone arm until the roller 200 moves off the projecting portion after which the member 163 is held by a rubber brake pad 205 but is released once in each revolution of the turntable to enable it to catch up the member 164 by engagement of a roller 211 on lever 198 by a projection 212 on the driving shaft. At the end of the record the tone arm and therefore the member 164 are moved in suddenly by the steeply pitched finishing groove while the member 163 remains held. As a result a tongue 173 on a triangular member 174 pivoted to member 163 is released from a shoulder formed in the wall of a groove in member 164 and a spring 185 is enabled to swing a lever 181 linked to member 174 about its pivot this movement being transmitted through projections 188 to a lever 187 which withdraws the lever 190 from the path of the disengaging pin on the clutch half 97. The cam is thus again coupled to the motor and replaces the shunt across the choke. During its return movement, the tone arm by means of the member 161 resets the members 163, 164, 174. Restoration of the button 153 to the " off " position moves the member 157 into the path of the screw head 96 on the cam and when the tone arm has been restored, member 157 is rocked by the screw head to withdraw the catch 139 from the slide 135 which thereupon switches off the motor and disengages the clutch. Rejecting unwanted record. Operation of the knob 194 (the throw of which is adjustable by an eccentrically mounted plate 196) during the playing of a record rocks the lever 190 to allow the clutch halves to re-engage whereupon the tone arm is restored and the next record is dropped into the playing position.