GB692195A - Panels - Google Patents

Abstract

692,195. Indicators for switches. PLASTECK, Inc. Jan. 24, 1950 [Aug. 8, 1949], No. 1804/50. Class 38 (v) [Also in Groups VIII, XV, XVIII, XIX and XXXI] panel for indicating-instruments switches comprises a layer of transparent material with a layer of translucent material superimposed and affixed to its front surface and an outer layer of opaque material at the front of the panel superimposed and affixed to the translucent layer, the apaque layer having at least one opening therethrough covered at its inner end by the underlying portion of the translucent layer, the panel having means for admitting light to the transparent layer to transilluminate the translucent layer at the opening in the opaque layer and diffusely illuminate it. A panel 10, particularly for aircraft instruments is formed of a centre layer 11 which is light-transmitting, layers 12 which are translucent and outside layers 13 which are opaque. The layer 11 is preferably thickest and is preferably a plastic material, e.g. poly-methyl methacrylate, though it may be of quartz, the layers 12 are preferably of cellulose acetate and the layers 13 preferably of a polyvinyl resin preferably with a matt finish. Light sources inserted in holes 20a with clear internal walls transmit light through the layer 11 to illuminate parts such as dials superimposed over areas 14 where the top layers 13, 12 have been cut away, and will illuminate without glare any indicia 15 formed by engraving only deep enough to remove the top opaque layer 13. Any holes 16, 18 drilled through the panel to receive shafts or pins of switches or other devices have their internal walls painted or lacquered to prevent light being transmitted therethrough. Where sleeves and insulation surrounding the light sources pass through the panel they are cut away leaving only bridge pieces. The panel may be laminated by coating the surfaces of adjacent layers with adhesive and passing the sandwich through rollers but lamination is preferably performed by bonding two translucent sheets to the centre layer by heat and pressure and repeating the process by bonding two opaque sheets to the first lamination. The layers 12,13 may comprise coatings of suitable material and thickness.