GB999179A - Improvements in or relating to a display device - Google Patents

Abstract

999,179. Warning and like lamps. IMPERIAL CHEMICAL INDUSTRIES Ltd. Jan. 15, 1964 [Feb. 21, 1963], No. 7070/63. Heading F4R. [Also in Division G5] A legend is, or characters forming a legend are each, formed from one or more polymethyl methacrylate Fresnel lenses, each such lens having illuminating means in its focal plane. Fig. 1 shows a letter D, cut from a complete lens (Fig. 3, not shown, is a cross-section) and mounted behind a face panel 2 (Fig. 2). Alternatively, parts of a whole lens may be obscured from view by a stencil. The lens elements are cemented to the rear of the panel 2, and a second transparent or translucent panel may be placed behind, the intervening space being sealed to protect the lens elements. The panel around the legend may be painted and the panel over the legend tinted to reduce reflection, so that the sign is legible only when lamp 5 is lit. Each character may have a lamp, or a common strip lamp may illuminate a row of characters. The lens elements may be coloured. Diffusing screen 6 may be coloured or additional coloured screens may be fitted, for example a screen on each side of a lens axis, in front of a diffusing screen, will make the lens element appear to change colour as an observer moves past. The function of the Fresnel lens element is that light is concentrated in particular areas, the sign being intended for warning or guiding aerial, rail and road traffic. The emitted beam may be made divergent by proper design of lens angles, or divergence in one plane only may be achieved using ribs on the backs of the lens elements. A coloured-sector disc may revolve behind characters to give changing colour effects.