US 5,690,422 AGranted

Sharp-cutoff luminaire having specular reflecting facets with fan-line geometry

AssigneeLighting Research & Development, Inc.

InventorJohn R. Brass

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Abstract

A fan-line optical principle for use in the design of faceted specular reflectors for sharp-cutoff luminaires is disclosed, and a luminaire embodying this optical principle is described. The luminaire described comprises a high intensity arc discharge lamp, providing a primary light source with finite length and thickness, and a reflector including a plurality of specular reflecting facets with fan-line geometry. Each of these fan-line facets displays (in a given main beam direction) a primary light source image that is parallel and adjacent to the cutoff edge of that facet. The name of this invention relates to the fact that a perspective view toward the front of a sharp-cutoff luminaire embodying the invention shows that fan-line facets, and the images they produce, create a fan-like pattern. An important characteristic of the invention is that the images of the primary light source displayed by fan-line facets, at a given main beam angle, can show substantially all of the primary light source.

Claims11

Dependent claims

A luminaire comprising:

a reflector including specular or semi-specular reflecting facets, said reflector further including a photometric axis and an opening for emitting light from a light source to an area to be illuminated;
a primary light source mounted within said reflector, said primary light source having a diameter and a longitudinal axis which is substantially perpendicular to said photometric axis;
a fan-like vertex axis located substantially in parallel with the longitudinal axis of the light source, at a distance approximately equal to one-half of the light source diameter, and between said light source and said reflector;
a plurality of fan-lines, each fan-line originating from a point on or near the fan-line vertex axis;
a plurality of said reflecting facets being fan-line facets, each of said fan-line facets having a cutoff edge lying substantially on one of said fan-lines, said cutoff edge being the facet edge which lies furthest from the opening;
whereby an image of said light source is displayed by each of said fan-line facets in a given direction, each said image being parallel and adjacent to said cutoff edge for each of said fan-line facets.

3 more elements

Dependencies are inferred from the claim text.