Patent GB-354661-A (GB)
Title: Improvements in and relating to holders for electric incandescent projection lamps
Filed: 1930-12-05
Abstract: 354,661. Electric lamp holders. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London.-(Assignees of Patent-Treuhand-Ges. f³r Elektrische Gluhlampen; 11, Ehrenbergstrasse, Berlin.) Dec. 5, 1930, No. 36725. Convention date, Feb. 7. [Class 39 (ii).] To facilitate the positioning of the lamp filament relatively to the optical system of a projection lamp, more particularly of the kind used in connection with talking-films, the lamp cap is vertically adjustable in a holding-sleeve which, together with the lamp cap mounted therein, is movable in the horizontal plane in two mutually perpendicular directions. The lamp holder consists of a cylindrical housing 1, Fig. 1, of insulating material containing a metal sleeve 2 which is provided at its upper end with slits 5, Fig. 5, to render it flexible and has a circular flange 3 at its lower end engaging an annular hollow 4 in the housing 1. Mounted within the sleeve 2 is another sleeve 6 formed with two upwardly projecting arms 7 which engage within a pair of diametrically opposite slits 8 in the sleeve 2 and at their upper ends are formed with claws 22 adapted to engage above the bayonet pins 23 of a lamp cap 24 inserted in the holder. An insulating plunger 9 mounted within the sleeve 6 forms a guide for a central contact pin 10, the lower end of which is provided with a head 12 which is in contact with the central portion of a blade spring 11 passing through the sleeves 2, 6 into small channels 13, Fig. 4 (not shown), in the housing 1. Axial adjustment of the lamp holder is effected by means of a bolt 17 with screw threads 10 engaging a rotatable sleeve 19 which is held against vertical movement by a pin 20 in the housing 1, an operating- head 21 being secured to the sleeve 19. The upper end of the bolt has a head 16 which engages, through an interposed insulating ring 15, with an inwardly projecting flange 14 on the lower end of the sleeve 6, so that when the head 21 is turned to retract the bolt 17 the claws 22 bear downwardly upon the pins 23 and depress the lamp cap in opposition to the pressure of the spring 11. Lateral adjustment of the lamp holder is effected by two radial screws 34, 37, Fig. 2, disposed at right-angles to one another and bearing upon the periphery of the flange 3 of the holder 2, a helical spring 36 in a housing 35 being disposed diametrically opposite to the screw 34, and a similar spring 40, Fig. 4 (not shown), being arranged opposite to the screw 37. The adjustment of the lamp is facilitated by an auxiliary device comprising a cover 41 which is mounted on the housing over the lamp bulb 25, and has a cover 42 provided with two apertures 43, 44 above a frosted glass plate 45. A lens 47 projects an image of the lamp filament 26 on to the glass beneath the window 43, while a second lens 48 at right-angles to the lens 47 and on a level with the filament, through an interposed prism 51, projects an image of the filament on to the glass beneath the window 44. Graduations 53, 54, 55, Fig. 3, on the glass enable the images of the filament to be adjusted correctly. The holder is provided with two contact pins 30, 31, Fig. 2, which project laterally from the housing 1 so that it can be connected to a socket and maintain the filament in its correct position.