Patent GB-317518-A (GB)
Title: Improvements in talking machines
IPC: G11B17/02
Filed: 1928-05-16
Abstract: 317,518. Gramophone Co., Ltd., and Thompsett, H. A. May 16, 1928. Magazine, gramophones; starting and stopping.-In a gramophone adapted for continuous playing, such as a magazine gramophone of the kind described in Specification 291,480, in which the machine is stopped automatically when there is no record on the turntable, means are provided to initiate the actuation of the stopping device during a cycle of automatic operations, and secondary means are provided to delay the final action of the stopping device until the automat.c cycle is completed. In the machine shown, the stopping device is a rotary switch comprising a casing 47 containing contacts (not shown) with which coact contacts carried by a plate 49 pivoted at 55 on a fixed plate 48. On the plate 49 is pivoted at 51 a spring-controlled catch lever 50, adapted to engage with a projection 57 on a detent 58 which is pivoted at 59 on the plate 48. A forked lever 70 engages with a pin 54 on the plate 49, and normally tends to rotate counterclockwise, Fig. 4, under the action of a spring 73. Such rotation is, however, prevented when the parts 50, 57 are in engagement, the switch members in the casing 47 then being held in the circuit-closing position, enabling the driving-motor to run. Mechanism is provided as described in Specification 291,480, comprising a clutch plate 5 on the turntable spindle 3, a lever 7 mounted thereon, and a lever 12 co-operating with the lever 7, the lever 12 bearing a pin 25 which engages with a ring 23 on a wheel 22. mounted on a shaft 19. A series of cams (not shown) on this shaft effect the cycle of operations incidental to the automatic changing of a record after one has been played, the complete cycle occurring during one revolution of the wheel 22. During the operation of the machine, when the playing of a record has been completed, the lever 12 is rocked by the means described in the aforesaid prior Specification, and allows the plate 5 to be clutched to the turntable spindle, whereupon the cam shaft 19 is driven. The pin 25 passes out of a depression 24 in the ring 23, and rides upon the inner surface of the ring as the latter rotates. By the operation of the cams on the shaft 19, the following effects are produced. A pillar 30 is lifted, and, through an arcuate plate 35 engaging a stud 36 on an arm 37 projecting from the tone-arm 14, raises the sound-box from the record. The tone-arm is then swung outwards by the action of levers 38, 39, as described in Specification 317,357. The played record is ejected from the turntable in any known manner, as for example by the action of a post 40 which rises and tilts the record on the turntable, enabling it to be slewed off. A new record is conveyed from a magazine to the turntable by an arm 45, operated as described in Specification 317,358. The tonearm is then lowered, as the pillar 30 moves downwards, until the needle engages the outer edge of the new record, and the return movement of the arm 45, away from the turntable, completes the cycle of operations. If, however, the last record of a series has been played, and consequently no new record has been fed to the turntable by the arm 45, when the tone-arm is lowered it falls to a position below the normal playing position, since the sound-box meets with no resistance when the needle reaches the level of the turntable. A stud 68 carried by an extension of the arm 37 thereupon depresses a lever 61, against the action of a spring. This lever has an inclined surface at its free end 69, which, when the lever is depressed, pushes the detent 58 aside so as to disengage the catch lever 50. Rotation of the plate 49 by means of the lever 70 would then occur, but for the fact that a stud 74 on the lever 70 is engaged by a projection 75 on the end of the clutch-controlling lever 12 as long as this lever is in the position it takes up when it initiates the rotation of the cam shaft 19. When, however, the shaft 19 has completed a revolution, the pin 25 enters the depression 24, and the lever 12 rocks into its normal position, so setting the lever 70 free to rotate the plate 49 and open the motor switch. The machine is started by rocking the lever 12 by means of a push-rod 76. Specification 291,719 also is referred to.