Patent GB-501111-A (GB)
Title: Improvements in and relating to electric lamps and in methods of manufacturing the same
IPC: H01K3/20
Filed: 1938-06-21
Abstract: 501,111. Photo-electric apparatus for centring lamp bulbs. BRITISH THOMSON-HOUSTON CO., Ltd. June 21, 1938, No. 18447. Convention date, June 21, 1937. [Class 40 (iii)] [Also in Groups XI and XXXVII] An electric lamp bulb 11, Figs. 1 and 2, the filament 17 is automatically adjusted in relation to the lamp base 10 by photo-electric apparatus. The bulb 11 is inserted through a hole in a plate 13 and rests in a cup 14 where it is held by suction from a pipe 15. The lamp base 10 is then placed over the bulb and rests on a shoulder in the hole in the plate 13. The leads 18, 19 from the bulb are then gripped by spring jaws 26, 27 connected by leads 28 to a source of current for lighting the filament. The light from the filament can fall on three photo-cells 33, between each of which and the filament is arranged one or two screens 31, 34. The edges of the screens are disposed at right-angles to each other in three different planes. If the filament is not in the correct position at the intersection of the optical axes 32, 44, 47 of the photo-cell devices, the cell or cells with which it is out of line causes the filament to be brought to the correct position by means of motors 35, 46, 43. The motor 43 rotates a screw 52 through a reducing gear 53, and the screw adjusts vertically a block 50 provided with an arm 49 carrying the cup 14 in which the lamp bulb is held; the motor 46 adjusts the motor 43 horizontally in one direction ; and the motor 35 adjusts the motor 46 in the other horizontal direction. As shown in the circuit diagram, Fig. 3, the motors 35, 43, 46 are series motors with two field coils and are connected to the mains 38, 39 through relays 40 controlled by amplifiers 37 connected to the photo-cells 33. A limit switch 56 is provided for the field coil of each motor to prevent over-running if the lighting of the filament fails. In a modification, Fig. 5, the screens have slits therein to determine the co-ordinate optical axes 68, 69, 83, the lamp bulb 11 is deliberately placed initially out of correct position, and the motors made to operate in one direction to bring the filament to the correct position, whereupon the motors stop. At first, both motors 35, 46 perform their aligning function, and when this is completed, the photo-cells 74, 75 connected to amplifiers 77 operate their relays 78, 79 to cause these motors to stop. At the same time, additional contacts 81, 82 are closed by the relays 78, 79 ; and these contacts being in series with the motor 43, this motor is started to produce the third adjustment. If the lighting of the filament fails, the motors are stopped by limit switches 64, which at the'same time close the circuit of a signal lamp 76. When the operation is completed, a walking-beam switch 65 is reversed to return the motors to their starting positions where they are stopped by limit switches 80, then the walking-beam switch 65 is replaced to operative position. In another modification, Fig. 6, three pairs of photo-cells 93, 94 are used with three screens 90, 91, 92 extending between them and the bulb 11. An incorrect, position of the bulb in relation to a screen illuminates one cell or the other of the pair, thereby causing the motors to correct the position. When the bulb 11 has been correctly adjusted it is cemented to the base 10 ; and, while heat is being applied to harden the cement, the electric supply to the apparatus is switched off. The lamp bulb and base holding means may be carried by a multiple head turret type of machine.