Patent GB-330699-A (GB)
Title: Improvements in or relating to record changing devices for talking machines
IPC: G11B17/00
Filed: 1929-04-19
Abstract: 330,699. Gramophone Co., Ltd., and Whitaker, A. April 19, 1929. Magazine gramophones. - A gramophone is provided with an electrically connected control device permitting the selection of one record out of a plurality of records and the setting into operation of a record-changing device, the selection being governed by the nature of the signal transmitted from the control device along a single electrical communicating channel. The control device comprises a spring-loaded perforated dial 37, Fig. 2, rotation of which causes the transmission of electrical impulses corresponding in number to the position to which the dial is rotated. Such a disc may ba of the type employed in automatic telephones. Each impulse is caused to energize a relay 40 which operates an electromagnet device 42 whereby a ratchet wheel 49 on a shaft 1 is rotated one tooth by a pawl 50. A second ratchet wheel 4 on the shaft 1 is thereby also rotated one tooth for each impulse received. A contact arm on the shaft 1 serves to make contact between pairs of contacts 2, 3, which are so arranged that each rotary step of the shaft 1 causes the arm to advance so as to make contact between a successive pair of contacts 2, 3. The contact member therefore takes up a position corresponding to the number of impulses sent by the dial, contact being made first with the righthand stud. When this contact is made, a circuit is closed from the terminals 7, connected to the source of electrical energy, through an arm 9 of a solenoid 10 to a contact stud 8 and through a solenoid coil A'. Similarly as the shaft rotates further the circuit through coil A<1> is broken and that through coil A<2> made, and so on. The solenoids A<1> - - A<4>, Fig. 1, are each provided with a plunger 11 having a grooved part 12 with which a spring-pressed lever 14 is adapted to engage when the plunger reaches the top of the coil. When the solenoid A' is energized, the plunger 11 is caused to rise against a spring 13 until the lever 14 engages in the groove 12. This movement of the plunger 11 rotates a shaft 16 having a cam 17 which closes a switch 18 shown in Figs. 1 and 2. The circuit of the solenoid A<1> is then opened by rotation of the shaft 1 and the circuit of the solenoid A<2> is closed, causing the corresponding plunger 11 to rise and at the same time to operate a bell-crank lever 35 which disengages the lever 14 from the groove 12 of the first plunger and allows the latter to fall. If four impulses are being sent, the operation proceeds until the plunger of the solenoid A<4> has risen. The switch 18, which lies in the main circuit of the record-selecting mechanism, is then kept closed. The selecting mechanism comprises a rod 19, Fig. 3, slidably mounted in a frame member 20 and adapted to be moved to the left, when the main circuit of the selecting mechanism is closed by means of a pivoted member 47 driven from an electric motor which is stopped when the rod 19 reaches its extreme left position by a suitable switch. An arm 23 slidably mounted on a pin 22 is adapted to be forced against a shoulder 24 on the rod 19 by a spring 25. The tops of the plungers 11, or members controlled thereby, act as stops for the arm 23, which is therefore stopped in its leftward movement at a position corresponding to the solenoid, which is in the raised position, and to the position of the selected record in the magazine. Further movement of the rod 19 effects, through cam means 26, 27, the engagement of a plunger 28 with a hole 30 in the pin 22, and thereby locks the arm 23 in position. The upward movement of the plunger 28 closes a switch 36 whereby mechanism for withdrawing the selected record from a magazine, transporting it to the turntable, and returning it alter playing is operated. When the record is returned to the magazine the rod 19 is caused to move to the right by the member 17 and in so doing unlocks the rod 23 and causes a peg 21 on the rod 19 to engage a switch 32, Figs. 2 and 3. A circuit is thereby closed through switches 18, 32 and solenoids 10, 33. The solenoid 10 attracts and disengages a pawl 6 which allows the ratchet 4 and shaft 1 to return to the position of rest under the action of the spring 5. The solenoid 10 also attracts the arm 9 and breaks the contact between the stud 8 and arm 9, thereby opening the circuits of the solenoids A<1> - - A<4>. The solenoid 33 serves to force the member 34 to the right so as to disengage the plunger of the raised solenoid. On further movement of the rod 19 the switch 32 is opened and the solenoids 10, 33 de-energized. If desired, the main circuit of the selecting mechanism may serve to trip a clutch so as to enable the record transporting mechanism to derive its motion from the turntable motor.