GB1140425A - Improvements relating to electrical apparatus - Google Patents

Abstract

1,140,425. Illuminating devices. LONDEX Ltd. 31 Aug., 1966 [11 Sept., 1965], No. 38890/65. Heading F4R. [Also in Division H1 and H2] Means for evenly illuminating a screen, which may bear an inscription, consists of a light source 1 (Fig. 1), which may be an incandescent filament directly illuminating the screen 2, a reflector 3 arranged to direct light from the lamp to the screen and a second reflector 5 arranged to reflect light from the lamp on to the reflector 3 and thence to the screen. The reflector 3 may be a cylindrical elliptical reflector and the reflector 5 plane. The screen may be backed by a cylindrical concavo-plane lens 8 with the concave surface towards the light source, and covered by a transparent plate 2. A colour filter 7 may be arranged so that all light from the source to the screen passes through it. Two such systems may be arranged in housings side by side in a casing to illuminate a single screen either separately or simultaneously, each housing being provided with an actuating bar for operating a switch assembly to produce variations in the illumination of the screen. The switch assembly consists of a block 16, Fig. 3, having sockets 17 into which connectors to the projeotors are plugged, and which has a slit 18 for insertion of the actuating bar. At the rear of the block is a cylinder 19 fitting on to a spigot 20 on a bobbin 21, a tube 22 passing through the cylinder and bobbin and carrying a permanent magnet 23 at the rear. Insertion of the actuating bar and movement of the block 16 towards the bobbin moves the magnet 23 relative to four dry reed switches. The bobbin also carries a coil, energization of which can operate one or more of the switches. A rear moulding 28a having a series of contact pins is arranged at the rear of the bobbin. The whole is housed in a casing assembly consisting of two halves having external ribs united by clips. The moulding consists of a block 39 having a series of connectors 40, some of which can be connected together by bus-bars 42 fitting into grooves 41 in the block. The blocks can be stacked on one another and the assemblage held by screwed rods 45, each provided with a flat 46 so that when the rod 45 is rotated any block in the pile can be withdrawn.