GB521851A - Improvements in and relating to electromagnetic devices for imparting movements to lamps - Google Patents

Abstract

521,851. Mounting electric lamps in lanterns. BRITISH THOMSON-HOUSTON CO., Ltd. Nov. 26, 1938, No. 34473. Convention date. Nov. 26, 1937. [Class 75 (iv)] [Also in Group XXXV] In electromagnetic apparatus for moving a lamp about a pivot the lamp support is connected to a shaft having an armature normally held in a position intermediate a pair of stator pole pieces so that equal and opposite torques are exerted thereon when the winding is energised and a second armature movable relative to the first armature is provided to unbalance the torques and enable the first armature to be moved to the required position. In the form shown, the lamp 10 is carried on a bracket 12 secured to the spindle 13 to which the armature 16 is secured, a second armature 17 being loosely mounted on the spindle 13. The armature 16 is urged to lie parallel with the stator pole pieces 13, 19 by a spring 20 but the axes of armatures 16 and 17 are displaced by a small angle limited by pins 25, 26 projecting from armature 17. When the winding 21 is energised, the pin end of the armature 17 will move towards the nearest pole-piece, i.e., pole-piece 18, Fig. 3, until the spring 30 on armature 17 engages a stop 32 on the pole-piece. Meanwhile armature 16 is moving to its attracted position and comes to rest bearing on pin 25. The armature 16 returns to the neutral position when 'the winding is deenergized and carries with it the second armature the pin end of which will now be nearer to the pole-piece 19 and hence the armatures move in the opposite direction when the winding is reenergized. During its movement the lamp filament is brought into and out of focus with the reflector 54.