Method and apparatus for light redistribution by internal reflection

• US 6,739,738 B1
• Filed: 01/28/2003
• Issued: 05/25/2004
• Est. Priority Date: 01/28/2003
• Status: Active Grant

• Current Assignee: Whelen Engineering Company Incorporated
• Original Assignee: Whelen Engineering Company Incorporated
• Inventors: Smith, Todd J.
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): TSIDULKO, MARK
• Application Number:
  US10/352,499
• Time in Patent Office: 483 Days
• Field of Search: 362/317, 362/331, 362/332, 362/235, 362/244, 362/245, 362/237, 362/297, 362/307, 362/308, 362/346, 362/341, 362/326, 362/327
• US Class Current: 362/317
• CPC Class Codes: F21S 10/06 flashing, e.g. with rotating reflector or light source signalling lighting devices mounted on vehicles B60Q1/26
• CPC Class Codes: F21S 43/14 Light emitting diodes [LED]
• CPC Class Codes: F21S 43/241 of complex shape
• CPC Class Codes: F21S 43/243 emitting light from one or more of its extremities
• CPC Class Codes: F21S 43/249 with two or more light sources being coupled into the light guide
• CPC Class Codes: F21S 43/26 Refractors, transparent cover plates, light guides or filters not provided in groups F21S43/235 - F21S43/255
• CPC Class Codes: F21S 43/315 using total internal reflection
• CPC Class Codes: F21V 2200/20 of light guides of a generally planar shape
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21W 2111/00 Use or application of lighting devices or systems for signalling, marking or indicating, not provided for in codes F21W2102/00 – F21W2107/00
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]

Abstract

A method and apparatus are disclosed for redistributing light to shift the apparent position of light generation and provide a more uniform area of light emission from a light assembly incorporating a plurality of spaced-apart light sources. Divergent light from each light source is collimated into a beam. Portions of each beam are diverted from the direction of the beam, transmitted laterally and redirected to emerge from the light assembly radially spaced from the position of the light source producing the beam. An internal reflecting lens member molded from optical plastic is disclosed as one apparatus for carrying out the method. The disclosed method and apparatus are particularly applicable to light assemblies incorporating an array of LEDs.

Claims

1. A method for redistributing light by internal reflection within a lens comprising the steps of:

receiving divergent light from a light source into a lens, said light source having an optical axis and a generally symmetrical light radiation pattern;

converting the divergent light into generally collimated light within the lens by internal reflection, said generally collimated light symmetrically distributed about said optical axis and having a first direction generally parallel to said optical axis;

diverting a first portion of said generally collimated light from said first direction to a second direction by internal reflection within the lens, while permitting a second portion of said generally collimated light to continue in said first direction;

redirecting said first portion from said second direction to a third direction by internal reflection within the lens, said third direction being generally parallel to said first direction,

whereby said first portion is emitted from the lens at a position radially displaced from said second portion and the optical axis of the light source.

2. The method of claim 1, wherein said step of diverting comprises:

arranging a first internal lens surface to reflect said first portion, said first internal lens surface having an angular orientation relative to said first direction such that said first portion is reflected generally perpendicular to said first direction.

3. The method of claim 2, wherein said first internal lens surface is planar.

4. The method of claim 2, wherein said first internal lens surface is curved.

5. The method of claim 4, wherein said curved first internal lens surface has a curvature defined by a portion of a parabola.

6. The method of claim 1, wherein said step of diverting comprises:

arranging a plurality of first internal lens surfaces to reflect said first portion, each of said plurality of first internal lens surfaces separated from an adjacent of said plurality of first internal lens surfaces by a lens portion which permits some of said second portion of said generally collimated light to continue in said first direction, each of said plurality of first internal lens surfaces having an angular orientation relative to said first direction such that said first portion is reflected generally perpendicular to said first direction.

7. The method of claim 1, wherein said step of redirecting comprises:

arranging a second internal lens surface to reflect said first portion from said second direction to said third direction, said second internal lens surface having an angular orientation relative to said second direction such that said first portion is reflected generally perpendicular to said second direction.

8. The method of claim 7, wherein said second internal lens surface is planar.

9. The method of claim 7, wherein said second internal lens surface is curved.

10. The method of claim 9, wherein said curved second internal lens surface has a curvature defined by a portion of a parabola.

11. The method of claim 1, wherein said step of redirecting comprises:

arranging a plurality of second internal lens surfaces to reflect said first portion, each of said plurality of second internal lens surfaces radially separated from an adjacent of said plurality of second internal lens surfaces, each of said plurality of second internal lens surfaces having an angular orientation relative to said second direction such that said first portion is reflected generally perpendicular to said second direction and generally parallel to said first direction.

12. A warning light assembly comprising:

an array of LED light sources, each LED generating diverging light;

an integrally formed lens member defining;

a plurality of collimators positioned to receive the diverging light generated by a corresponding one of the LEDs and convert said diverging light into a substantially collimated beam having a first direction;

a first internal lens surface arranged to divert part of at least one of said collimated beams in a second direction by reflection within the lens, said second direction being substantially perpendicular to said first direction;

a second internal lens surface arranged to receive and redirect light from said first internal lens surface in a third direction by reflection within the lens, said third direction being substantially perpendicular to said second direction and substantially parallel to said first direction;

wherein light redirected by said second internal lens surface is emitted from said lens member radially spaced from said at least one of said collimated beams.

13. The warning light assembly of claim 12, wherein said first and second internal lens surfaces are planar.

14. The warning light assembly of claim 12, wherein said first and second internal lens surfaces are curved.

15. The warning light assembly of claim 12, wherein said first internal lens surface comprises a plurality of first internal lens surfaces separated by lens portions that permit part of the at least one of said collimated beam to be emitted from said lens member without being diverted from said first direction.

16. The warning light assembly of claim 12, wherein said second internal lens surface comprises a plurality of second internal lens surfaces, each of said plurality of second internal lens surfaces being radially separated from the other of said plurality of second internal lens surfaces.

17. A lens member for a light assembly comprising a plurality of light sources generating divergent light, said lens member comprising:

a collimator arranged to receive the divergent light from a light source and convert said divergent light into a substantially collimated beam by internal reflection, said substantially collimated beam having a first direction and a first position relative to the light source; and

a light pipe comprising;

a first internal lens surface arranged to divert a portion of the substantially collimated beam from said first direction into a second direction;

a second internal lens surface arranged to redirect light from said first internal lens surface into a third direction; and

a lens portion for transmission of light from said first internal lens surface to said second internal lens surface,

wherein said light redirected by said second internal lens surface is emitted from said lens member at a second position radially spaced from said first position.

18. The lens member of claim 17, comprising a collimator and light pipe for each of said plurality of light sources.

19. A method for shifting the apparent position of light generation in a light assembly, said light assembly comprising a light source generating divergent light and having an optical axis, said method comprising:

collimating the diverging light from said light source into a substantially collimated beam substantially symmetrically arranged about said optical axis and having a first direction substantially parallel to said optical axis;

arranging a first lens surface to divert a portion of said substantially collimated beam from said first direction into a second direction;

transmitting said portion radially relative to said optical axis; and

arranging a second lens surface to redirect said portion into a third direction,

wherein said portion is emitted from said light assembly at a position radially displaced from said optical axis.