Patent GB-386922-A (GB)
Title: Improvements in or relating to gramophone and the like sound reproducing apparatus
IPC: G09F25/00
Filed: 1932-09-16
Abstract: 386,922. Gramophones. LINDEN, L. P., 28, Cock Lane, London. Sept. 16, 1932, No. 25802. [Class 40 (ii).] A gramophone, to be used for advertising purposes, has a continuouslyrotating record and means are operated by stepping on a platform to lower the reproducer into contact with the record and subsequently to raise the reproducer after a predetermined period of reproduction. The turntable 1, Figs. 1 and 2, is driven from an electric motor 3 by a belt 4 which passes over a pulley secured to the turntable spindle 2. The tone-arm 10 swivels in a ball bearing 14 and has an extension 10c depending below the main frame 15. Fixec to the extension 10a, for rotation therewith is a frame 16 which supports the means for raising and lowering the tone-arm. This means comprises a piston 18 working in a cylinder 17 which has an inlet pipe 17a. A buffer spring 18b is located on the inlet side of the pistor and a compression spring 18c on the other side and the free end of the piston slidably engages with an L-shaped member 20 which is pivoted at 20b to the frame 16. The other end of the member 20 is notched and engages a rod 21 which passes up through the tone-arm where it is fixed to one end of a pivoted lever 24 engaging the freely movable front portion of the tone-arm. The rod 21 is connected by a ball joint 21a to the movable iron core 22 of a solenoid 23 fixed to the frame 16. The other end of the core 22 is connected to an L-shaped member 26 pivoted at 26a to an extension of the frame 16 and carrying a contact 26b adapted to register with a contact 28, these contacts being normally kept open against the action of a compression spring on the core 22. A second cylinder 32, Fig. 2, has a piston 33 connected by a link 34 to a cam 35 which bears upon a trip lever 36 pivoted at 37 and biased by a spring 39. The other end of the lever 34 is provided with a catch 38 which coacts with a slot in a pivoted strip 40 whose lower end is attached to the core 42 of a solenoid 43. A shaft 45 geared to the turntable spindle 2 passes through an aperture in the strip 40, and mounted loosely on the shaft, and loosely associated with the strip 40, is a disc 47 which has four pins 48 adapted to engage with the teeth of a wheel 49 fixed to the shaft 45, a spring 51 tending to urge the disc 47 towards the wheel 49. Supported in the path of a projecting pin 53 on the disc 47, is a pair of fly contacts 52. A stop 55 projects into the path of the stops on the ends of the pins 48 so that, when the pins are disengaged from the wheel 49, the disc 47 is prevented from turning with the shaft 45. To enable the tone-arm to be transferred from the end to the beginning of a record, it is provided with an arm 56, Figs. 1 and 3, to which is pivoted a flexible strip 57 which carries a pin 58 passing through the central aperture of a collar 59 slidable in a slot in a strip 60 fixed to the frame 16, a spring 59a being inserted between the collar 59 and the strip 57. The strip 60 lies above a disc 61 mounted to rotate with the spindle 2 and provided with a spiral groove 62 which ends in a circular groove at the periphery and into which the pin 58 is thrust, when the tonearm reaches the end of a record, by means of a stop 1a on the underside of the turntable. The strip 57 is provided with a curved slot 63 in which is guided a pin 64 mounted on a carriage 65 which rides on a guide-rail 66. Each end of the slot 63 is enlarged to enable a collar 67 on the pin 64 to pass therethrough. When the pin 58 is thrust into the inner end of the spiral groove, the strip 57 is moved outwardly and is depressed sufficiently to allow the collar to pass through the slot at the end 63a so that the pin 64 passes along the slot 63 until it reaches the. end 63b when the strip 57 springs over the collar 67 and the pin 58 is withdrawn from the, groove 62. Due to this movement of the strip 57, the arm 56 turns the tone-arm to the commencement of the record. The record reproduces one slogan at each revolution and to ensure that the stylus is lowered into the next successive record groove a pin 68, Fig. 5, rotatable with the tone-arm, is adapted to engage a stationary toothed rack and to be moved horizontally by levers operated by the means for lifting and lowering the tone-arm. When the latter is raised, the pin 68 engages the rack 69, the pitch of whose teeth corresponds with that of the record grooves, so that the pin 68 is guided by the side of a tooth into a recess to give the tone-arm a slight sidewise movement and bring the stylus over the next record groove. In operation, a bellows is depressed by a person stepping on a platform and a puff of air is transmitted to the cylinders 17, 32 to operate the pistons 18, 33. The piston 18 causes the tone-arm to be lowered while movement of the core 22 closes the contacts 26b, 28, the piston then returning to its normal position under the influence of the spring 18c. Simultaneous operation of the piston 33 turns the cam 35 to operate the trip lever 30 to release the strip 40 and allow engagement of the disc 47 and toothed wheel 49, while also causing the core 42 to be pulled out. The disc 47 is thus rotated and, when the pin 53 momentarily operates the fly contacts 52, the circuits of the solenoids 23, 43 are closed to retract the cores 22, 42. Retraction of the core 22 causes the contacts 26b, 28 to open, so breaking the circuit of the solenoids and also moving the rod 21 to the lett to raise the tone-arm. Retraction of the core 42 causes the strip 40 to rotate in an anticlockwise direction, Fig. 2, until held by the catch 38, thereby moving the disc 47 away from the wheel 49 to bring the mechanism into its original position in readiness for the next operation.