Illumination device for producing predetermined intensity patterns

• US 6,367,941 B2
• Filed: 06/07/2001
• Issued: 04/09/2002
• Est. Priority Date: 02/24/1999
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Lea, Michael Charles, Lundin, David Jon
• Primary Examiner(s): Cariaso, Alan
• Application Number:
  US09/876,001
• Publication Number:
  US 20010038539A1
• Time in Patent Office: 306 Days
• Field of Search: 362/26, 362/31, 362/551, 362/559, 362/560, 362/561, 362/582, 349/62, 349/65, 385/31, 385/123, 385/129, 385/901
• US Class Current: 362/619
• CPC Class Codes: G02B 6/001 the light being emitted along at least a portion of the lateral surface of the fibre
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

An illumination device produces a desired illumination pattern by tailoring the configuration of individual light extraction structures. At least two of the light extraction structures have different configurations from one another. The illumination device includes a light guide having a light guide core and an optically smooth surface for propagating light through the core. A light emitting region extends along a portion of the core and includes a plurality of light extraction structures distributed along the optically smooth surface. The light extraction structures are configured so that light reflected therefrom is emitted from the light guide through the optically smooth surface.

Claims

1. An illumination device, comprising:

a light guide including a light guide core having an optically smooth surface for propagating light therethrough and a light emitting region extending along a portion of the core, the light emitting region including;

a plurality of light extraction structures distributed along the optically smooth surface of the light guide core, each light extraction structure including an optically reflective surface extending into the light guide core and oriented to reflect light at an angle less than a critical angle so that light is emitted from the light guide through the optically smooth surface, each such optically reflective surface forming a notch angle with respect to an axis that extends from the respective light extraction structure to a side of the optically smooth surface opposite such light extraction structure;

wherein at least one of the light extraction structures has a notch angle that is different from a notch angle of at least one other light extraction structure; and

wherein the plurality of light extraction structures include a series of light extraction structures defined by a particular sequence of notch angles, said series of light extraction structures being repeated a prescribed number of times along the optically smooth surface of the light guide core.

2. The device of claim 1, wherein the light guide is a light fiber.

3. The device of claim 2, wherein the light fiber has a circular cross-sectional shape.

4. The device of claim 2, wherein the plurality of light extraction structures are distributed along a plurality of longitudinal axes of the light fiber.

5. The device of claim 1, wherein the plurality of light extraction structures are equally spaced apart from one another along the optically smooth surface.

6. The device of claim 1, wherein the plurality of light extraction structures are unequally spaced apart from one another along the optically smooth surface.

7. The device of claim 1, wherein said light guide is formed from a polymerizable material.

8. The device of claim 7, wherein the polymerizable material is selected from the group consisting of acrylate, urethane, and silicone materials.

9. A method for generating a prescribed illumination pattern, said method comprising the steps of:

providing a light guide that includes a light guide core having an optically smooth surface for propagating light therethrough and a light emitting region extending along a portion of the core, the light emitting region including;

a plurality of light extraction structures distributed along the optically smooth surface of the light guide core, each light extraction structure including an optically reflective surface extending into the light guide core and oriented to reflect light at an angle less than a critical angle so that light is emitted from the light guide through the optically smooth surface, each such optically reflective surface forming a notch angle with respect to an axis that extends from the respective light extraction structure to a side of the optically smooth surface opposite such light extraction structure; and

arranging at least first and second notch angles to be different from one another so that light emitted through the optically smooth surface is emitted in the prescribed illumination pattern;

wherein the plurality of light extraction structures include a series of light extraction structures defined by a particular sequence of notch angles, and further comprising the step of repeating a prescribed number of times said series of light extraction structures along the optically smooth surface of the light guide core.

10. An illumination device, comprising:

a light guide including a light guide core having an optically smooth surface for propagating light therethrough and a light emitting region extending along a portion of the core, the light emitting region including;

a plurality of light extraction structures extending along the optically smooth surface of the light guide core, said light extraction structures having an optically smooth reflective surface and being configured so that light reflected therefrom is emitted from the light guide through the optically smooth surface; and

wherein at least two of the light extraction structures have different configurations from one another; and

wherein each light extraction structure has a notch angle denoting the angle between an optically smooth reflective surface of the light extraction structure and an axis extending from the light extraction structure to a side of the optically smooth surface opposite such light extraction structure, and wherein the plurality of light extraction structures include a series of light extraction structures defined by a particular sequence of notch angles, said series of light extraction structures being repeated a prescribed number of times along the optically smooth surface of the light guide core.

11. The device of claim 10, wherein the optically smooth reflective surface for each light extraction structure extends into the light guide core and is oriented at the respective notch angle to reflect light at an angle less than a critical angle so that light is emitted from the light guide through the optically smooth surface.

12. The device of claim 10, wherein said different configurations correspond to different notch angles.

13. The device of claim 10, wherein said light guide is a light fiber.

14. The device of claim 10, wherein said light guide has a circular cross-sectional shape.

15. The device of claim 10, wherein said light guide is a planar light guide.