Cover plate for a lamp

Claim 1

A cover plate for a lamp having centrically symmetrical light refractory configurations on one surface thereof wherein said one surface of the plate is traversed by parallel ribs of V-section, a first set of a plurality of said ribs running in each of a longitudinal direction and a direction transverse thereto, and a second set of said ribs running in two diagonal directions transverse with respect to each other, said diagonal ribs being equally spaced whereby the vertex lines defined by the crests of said second set of ribs divide the plate, when viewed in plan, into principal and secondary square divisions in a checkerboard pattern, said first set of ribs being formed in pairs of parallel ridges having overlapping cross-sections, the cross-sectional shape of the ribs being extended forming prismatic depressions in the form of inverted pyramidal depressions between the ribs in both the principal and secondary square divisions, the inverted pyramidal depressions in each principal square division comprising a centrally located octagon with four triangles contiguous to four sides of the octagon forming a complete principal square, and the inverted pyramidal depressions in each secondary square comprising a centrally located square with four pentagons and four triangles alternately positioned contiguous to the perimeter of the square forming a complete secondary square; and the opposite surface of said plate has a boss-like elevation opposite each of said inverted pyramidal depressions whereby an improved light-scattering effect is obtained and a lamp located adjacent said opposite surface of said plate is not visible from the one surface thereof.