Patent GB-755393-A (GB)
Title: Improvements in and relating to mount inspecting devices
IPC: H01J9/42
Filed: 1954-10-08
Abstract: 755,393. Making electric lamps and discharge devices. BRITISH THOMSON-HOUSTON CO., Ltd. Oct. 8, 1954 [Oct. 9, 1953], No. 29084/54. Class 39(2). Apparatus for inspecting the mounts of electric lamps and discharge devices carried in a turret machine which indexes them through successive work stations comprises wire feelerdevices which are moved into abutment with the filament support wires prior to the attachment of a filament thereto, and an associated movable means which towards the end of its movement operates an electric switch in a filament-feeding control circuit, the relative arrangement being such that the switch actuating means is operative when the filament support wires are in their normal position but is rendered inoperative and accordingly prevents the feeding of a filament to the particular mount at a subsequent work station if one of its filament support wires is missing or is positioned incorrectly. Means are also provided to prevent the feeding of a filament if the inner ends of two filament support wires sealed within the glass arbor button of the mount are in contact. In the example the inspecting device is applied to lamp mounts having a spider comprising seven filament support wires 2 radiating from a button at the lower end of the vitreous arbor 9 of a stem 3, the mounts being secured around the periphery of an indexing turret by pairs of jaws 5 gripping the exhaust tubes 6 in known manner. The successive mounts are halted at the faultdetecting station at which feelers 8 are lifted into engagement with the support wires 2 in synchronism with the presentation of the mounts at the station. The feelers 8 are arranged about the axis of the stem 3, each being pivoted on a pin 10 extending laterally from the side of a standard 11 mounted upon a circular carriage plate 12. Each feeler comprises a sensing portion 15 extending horizontally towards a support wire 2 so that its end, which is offset to an L-shape engages beneath the wire 2 due to a counterbalancing portion 13 and a lower control . portion or tail 14, the latter swinging normally, to a vertical position directly below the pivot 10. Upward movement of the carriage 12 is effected by a push rod 16 which is controlled by a cam 18 engaging a roller 25 supported by a lateral arm 27 secured on the lower end of rod 16, the upper end of the rod 16 having secured to it a platform 20 provided with a seating for a helical spring 23 surrounding a guide rod 19 depending from the carriage 12, so that upward vertical movement of rod 16 is transmitted through spring 23 to the carriage 12. The guide rod 19 extends down through the platform 20 and through apertured guiding ears 21, 22 projecting from a standard 17 mounted on the base plate 1. A stop 28 secured on the guide rod 19 limits the upward movement of the carriage 12 by abutting against the guide ear 21. The platform 20 carries a bracket 30 formed with a bifurcated offset upper portion providing upper and lower bearings for the vertical spindle 31 of a horizontal disc 29. A helical spring 32 is located around the lower end of the spindle 31. In operation, if all the filament support wires 2 are located correctly, upward movement of the carriage 12 brings the sensing portions 15 of all the feelers against the undersides of all the support wires whereby the feelers are all swung to the relative position shown in Fig. 1, and their parts 14 are moved clear of the disc 29, so that the support bracket 30 brings the upper end of the spindle 31 against an actuating arm 33 which closes a switch 34 in the circuit of a relay to effect the feeding of a filament to the mount when it arrives at the filament receiving station. If, however, due to a missing or bent support wire 2 the path of the sensing portion 15 of one of the feelers is not impeded, so that the control portion 14 of the feeler hangs vertically or is not turned sufficiently to clear the path of motion of the rim of the disc 29, the latter will be blocked against further movement since its upward pressure is insufficient to turn the feeler out of position,- the pressure being directed vertically against,the pin 10 and taken up by the spring 32. The full upward movement of the disc 29 can thus be blocked by any one of the feelers. causing the disc and its spindle 31 to be displaced axially within the supporting bracket and preventing operation of the switch arm 33. The switch 34, when closed, completes a circuit through a relay 39, Fig. 2, and the secondary winding of a transformer 41 to energise a control solenoid 35 associated with the filament feeding mechanism, which is of the kind described in Specification 390,807, this operation taking place each time a mount 3 with proper arrangement of support wires 2 is inspected. The solenoid withdraws a stop pin 43, Fig. 3 (not shown) from the path of travel of a cam-operated rocking-lever, the upper end of which engages the side of a plate carrying the filaments transversely between a series of pairs of vertical pins. When, due to a defective mount at the detecting station, the stop-pin remains in the path of the rocking lever a pivoted stub on the upper end of the latter is held against further movement, and the continuing operation of its actuating cam is taken up by a tensioned spring. In order to test for contact between the sealed ends of any pair of the support wires 2 radiating from the arbor, alternate feelers 8 are interconnected together by wires such as 62-64, Fig. 2, and the feeler supports 11 are insulated from the actuating parts of the device, the carriage 12 and disc 29 also being made of insulating material. Two duplicate connecting devices comprised of a lead 67 from one of the standards 11 associated with each group of feelers 8, and a fine coil of wire 68 and a metal thimble 69 connect the movable parts of the device to the leads 60, 61 of a stationary terminal block. Contact between any adjacent pair of support wires will result in the relay 39 breaking the circuit through the secondary of the transformer 41 to the control solenoid 35 of the filament feeding apparatus.