GB669993A - Improvements in and relating to lighting fittings - Google Patents

Abstract

669,993. Lighting systems. BENJAMIN ELECTRIC, Ltd. (Benjamin Electric Mfg. Co.). Aug. 9, 1948. No. 20980/48. Class 75(iv). In a lighting installation, light from a plurality of lighting units 1, mounted overhead, is directed downwardly on to a substantially continuous, louvred false ceiling 6 formed by a criss-cross arrangement of horizontally extending translucent strips 7, 8, having light diffusing surfaces. The false ceiling is built up from rectangular louvre sections 6a which rest on frames formed by channel members 9 connected at their ends by corner pieces 12. In the latter, two or more flanged arms are either rigidly disposed at right angles or pivoted to each other and holes are provided for connection to supporting rods 13 depending from the true ceiling. The translucent strips 7, 8 are made of sheet plastic material with roughened surfaces, which are formed either by the extrusion process for making the sheets or by rolling the sheets between rollers having different speeds. The strips have slits extending from one edge to the middle, so that when assembled the lower and top edges of both sets of strips lie in the same two spaced planes. A liquid cement may be applied to the intersections of the strips. The light-transmitting factor of the strips is several times greater than the light-reflecting factor. The width and spacing of the strips are chosen in accordance with the spacing between the lighting units and with the desired cut-off angle. The distance of the upper edges of the strips from the plane of the lighting units is several times greater than the width of the strips. Each lighting unit comprises a reflector 5, and one or more straight fluorescent lamps 4, extending parallel to one set of louvre strips.