Light guide
A light guide for luminaires is disclosed. In some embodiments the light guide is oriented to receive light from a point light source at a light receiving surface configured to refract incoming light at angles to enable total internal reflection (TIR) of the light down the body of the light guide without loss of light. A foot at the bottom of the body of the light guide includes a first sloped face wherefrom a portion of the light is extracted downward toward a work plane in a batwing distribution and a second sloped face and a return face wherefrom the remaining light is extracted upward.
1. A light guide comprising:
a body comprising:
an inner major surface;
an outer major surface opposite the inner major surface; and
an upper edge comprising a light receiving surface comprising a plurality of spaced apart grooves;
a foot continuous with the body and opposite the upper edge, the foot comprising:
an outwardly and downwardly sloping first face for extracting light, the first face adjacent the inner major surface and extending from about a plane of the inner major surface to beyond a plane of the outer major surface;
an outwardly and upwardly sloping second face for extracting light, the second face adjacent the first sloped face;
at least one return face connecting the second face to the outer major surface, wherein the body has a circular cross-section and the first face, second face, and return face are circular.
2. A light guide according to claim 1 wherein one end of the first face adjoins the inner major surface and another end of the first face adjoins the second face.
3. A light guide according to claim 1 wherein the body is clear.
4. A light guide according to claim 1 wherein the first face comprises a plurality of flutes.
5. A light guide according to claim 1 wherein the first face is diffuse.
6. A light guide according to claim 1 wherein an angle α between the first face and a horizontal plane is about 10 to 40 degrees, or about 30 degrees.
7. A light guide according to claim 1 wherein the second face is diffuse.
8. A light guide according to claim 1 wherein the second face is clear.
9. A light guide according to claim 1 wherein an angle β between the second face and a horizontal plane is about 60 to 80 degrees, or about 65 to 75 degrees, or about 70 degrees.
10. A light guide according to claim 1 wherein the plurality of spaced apart grooves are spaced evenly apart and each configured to receive a point light source.
11. A light guide according to claim 1 wherein the plurality of spaced apart grooves have cross-sections at least partially defined by rounded V-shapes.
12. A light guide according to claim 11 wherein a height H of the body is about 1.5 to 3 times, or about 2 times, the width Wv.
13. A light guide according to claim 12 wherein a height H of the body is about 1 to 2 times, a width W of the spaced apart grooves.
14. A light guide according to claim 1 wherein a horizontally projected length L 1 of the first face 116 is greater than a horizontally projected length L 2 of the second face.
15. A light guide according to claim 14 wherein the ratio of the length L 1 to the length L 2 is between 2:1 to 4:1, or about 2.5:1 to 3.5:1, or about 3:1.
16. A light guide according to claim 1 wherein the body comprises a right circular cylindrical shape.
17. A light guide according to claim 1 wherein the body is a right truncated conical shape.
18. A luminaire comprising:
a housing;
a light guide according to claim 1 ;
a plurality of point light sources, each light source received in a corresponding one of the plurality of spaced apart grooves;
whereby light from each light source spreads from the light receiving surface to the foot and is extracted at least the first face and the second face.