GB558565A - Improvements in and relating to electric discharge lamps - Google Patents

Abstract

558,565. Lamp-holders two-part couplings. BRITISH THOMSON-HOUSTON CO., Ltd. July 7, 1942, No. 9393. Convention date, July 11, 1941. [Class 38 (i)] [Also in Group XL] A holder for a tubular discharge lamp having a socket to receive a starter switch device, has the socket contacts and connections so arranged that starter switch devices of different types can be inserted. The socket has four concentric curved slots to receive the pin contacts of the switch device, two of the slots being of keyhole type to receive and lock two headed pins which are provided on each type of switch device. The plain slots receive pins which are present on one type and not on another, and the contacts associated with these slots are normally shortcircuited, the short circuit being opened when pins engage the contacts. The lamp-holder contacts are connected through leads or the screws 32, 41 to terminal plates 30, 39 to which are attached blade contacts 25, 35 associated with two of the curved slots 22, 23 of the socket. Similar contacts 24, 34 associated with the other slots are attached to supply terminals 27, 36. The contacts 35, 34 are normally bridged by a conductive strip 43. When a glow starter switch such as described in Specification 541,925, [Group XXXVII], is used, its two contact pins enter the keyhole slots 22 and engage the contacts 24, 25, leaving the contacts 34, 35 bridged By the strip 43, the connections being as shown in Fig. 11. The bimetallic strip 75 of the switch is deflected when the glow discharge from it to the plate 76 operates and closes the circuit through the filaments 67, 70 and immediately opens it again leaving the filament 67 connected through the contacts 35, 34 to one line 64 of the supply, the other filament being directly connected to the other line 71. With a switch having a bimetallic strip and a heating coil, the switch base has four pins, the two which enter the slots 23 engaging the contacts 34; 35 and moving them away from the bridging strip 43, to establish the circuit shown in Fig. 8. The contacts 59, 60 on the bimetallic strip 56 and the rigid blade 61 of the switch are normally closed, the current passing initially through these contacts, the filaments 67, 70 and the heating coil 50. When the contacts 59, 60 separate the discharge through the lamp is established, but the current still flows in the heating coil 50 preventing, closure of the contacts 59, 60 while the lamp is in operation. Specification 556,536 also is referred to.