Light pipe having optimized cross-section

• US 5,309,544 A
• Filed: 03/31/1992
• Issued: 05/03/1994
• Est. Priority Date: 03/31/1992
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Saxe, Steven G.
• Primary Examiner(s): Bovernick, Rodney B.
• Assistant Examiner(s): BARNS, STEPHEN
• Application Number:
  US07/861,243
• Time in Patent Office: 763 Days
• Field of Search: 385/146, 385/147, 385/133, 385/901
• US Class Current: 385/146
• CPC Class Codes: G02B 6/0096 the lights guides being of the hollow type
• CPC Class Codes: G02B 6/10 of the optical waveguide type G02B6/02, G02B6/24 take precedence; devices or arrangements for the control of light by electric, magnetic, electro-magnetic or acoustic means G02F1/00; transferring the modulation of modulated light G02F2/00; optical logic elements G02F3/00; optical analogue/digital converters G02F7/00
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

A luminaire includes a light pipe having an optical axis. The light pipe includes a tube with a structured outer surface and a smooth inner surface. A reflective light extractor is positioned in the tube such that light reflected by the extractor will strike the tube on a first side. The first side has a contour such that the direction of travel of light reflected by the extractor will have a projection in the plane perpendicular to the optical axis that makes a predetermined angle with the smooth surface.

Claims

1. A luminaire comprising a light pipe, said light pipe comprising a tube having an optical axis and a structured outer surface and a smooth inner surface and a reflective light extractor inside said tube, said extractor being positioned within said tube such that light propagating in said tube in a direction generally along said optical axis and striking said extractor will be reflected in a direction such that it will strike said tube on a first side thereof, said first side of said tube having a contour such that said direction of reflected light will have a projection in a plane perpendicular to said optical axis that makes a predetermined angle with said smooth surface.

2. A luminaire according to claim 1 wherein the contour of said first side is such that said light propagating said tube generally along said optical axis and reflecting from said extractor will be reflected in a direction within a range such that a projection of said direction in a plane perpendicular to said optical axis will strike said smooth surface at an angle to a normal to said smooth surface in the range of 30 degrees to 75 degrees.

3. A luminaire according to claim 2 wherein the contour of said first side is such that said light propagating said tube generally along said optical axis and reflecting from said extractor will be reflected in a direction within a range such that a projection of said direction in a plane perpendicular to said optical axis will strike said smooth surface at an angle to a normal to said smooth surface in the range of 50 degrees to 70 degrees.

4. A luminaire according to claim 3 wherein said angle is approximately 60 degrees.

5. A luminaire according to claim 2 wherein said structured outer surface comprises a plurality of triangular prisms, each prism having an axis running parallel to said optical axis.

6. A luminaire according to claim 5 wherein said prisms are right isosceles prisms.

7. A luminaire according to claim 6 wherein said angle is approximately equal to 60 degrees.