GB1314401A - Cover plate for a lamp - Google Patents

Abstract

1314401 Light refracting plates TRILUX-LENZE KG 20 May 1970 [6 June 1969] 24400/70 Heading F4R A light refracting cover-plate for a lamp is traversed in at least three directions by sets of straight parallel generally V-shaped grooves the bottoms of which divide the plate into principal divisions, in the form of hexagons, octagons, decagons or higher order polygons, and secondary divisions in the form of triangles or polygons, each division being surmounted by a pyramidal elevation. In a preferred embodiment, Fig. 1, the plate has longitudinal and transverse grooves arranged in overlapping pairs 120, 120a, the lower and upper portions 122, 123 of the sides of the grooves being of different pitch and separated by a discontinuity line 124, and two sets of diagonal grooves 110 having side portions 112, 113 separated by a discontinuity line 114 at the same level as the line 124. The grooves give rise to a series of principal and secondary squares 100, 200 arranged in checkerboard configuration, each principal square containing a regular octagon 101 surmounted by a pyramid with vertex 102 and four corner triangles surmounted by pyramids 104 and each secondary square containing a central pyramid 201 on a square base, four corner pentagons 211 surmounted by pyramids with vertices 212, and four triangles 221 surmounted by pyramids with vertices 222. Discontinuity lines formed by the lines 114, 124 on the sides of the grooves are shown at 103, 203, 213 on the higher pyramids. In modifications the sides of the grooves are concave or curved, and the pyramids are irregular or eccentric. A tool for use in making the cover-plate bears a negative impression of the surface configurations to be formed on the plate, the tool itself being made using a die having a surface configuration identical with that of the plate. Such a die can readily be made simply by cutting the grooves using known mechanical processes. The die itself may be used to form cover-plates having a negative impression compared to that described above, and the invention embraces such negative plates.