LIGHT DISTRIBUTION USING A LIGHT EMITTING DIODE ASSEMBLY

• US 20090161359A1
• Filed: 12/21/2007
• Published: 06/25/2009
• Est. Priority Date: 12/21/2007
• Status: Active Grant

• Current Assignee: Ilumisys Incorporated (Altair Engineering Incorporated)
• Original Assignee: Altair Engineering Incorporated
• Inventors: Siemiet, Dennis, Palazzolo, Francis, Ivey, John
• Granted Patent: US 7,712,918 B2
• Time in Patent Office: Days
• US Class Current: 362/235
• CPC Class Codes: F21K 9/61 using light guides
• CPC Class Codes: F21K 9/68 Details of reflectors forming part of the light source
• CPC Class Codes: F21S 4/28 rigid, e.g. LED bars
• CPC Class Codes: F21V 3/00 Globes; Bowls; Cover glasses with refracting properties F21V5/00; with reflecting properties F21V7/00; characterised by cooling arrangements F21V29/506
• CPC Class Codes: F21V 3/04 characterised by materials, surface treatments or coatings
• CPC Class Codes: F21V 3/049 Patterns or structured surfaces for diffusing light, e.g. frosted surfaces
• CPC Class Codes: F21V 7/00 Reflectors for light sources characterised by cooling arrangements F21V29/505
• CPC Class Codes: F21Y 2103/10 comprising a linear array of point-like light-generating elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A fluorescent light tube retrofit with light emitting diodes (LEDs) that evenly distribute light to avoid bright spots is disclosed. One tube in the form of a conventional fluorescent tube includes two LEDs mounted to the tube on opposite sides of a single circumference of the tube. The LEDs can face the center of the tube, or the LEDs can be offset facing relative to the center of the tube. A reflecting surface can be disposed inside the tube to reflect light evenly toward an arc of the tube. Alternatively, at least one LED can be oriented to direct light into a light pipe that curves around the interior of the tube.

Claims

1. A LED lighting unit for replacing a conventional fluorescent bulb of a conventional fluorescent lighting fixture comprising:

a tubular housing including at least one tube portion;

a first LED assembly including a plurality of LEDs, the first LED assembly located along a first longitudinal length of the tubular housing and oriented to face an interior of the tubular housing; and

a second LED assembly including a plurality of LEDs, the second LED assembly attached to a second longitudinal length of the tubular housing and oriented to face the interior of the tubular housing, wherein the tubular housing, the first LED assembly and the second LED assembly are configured such that a substantially similar amount of light strikes the tubular housing around its entire circumference.

2. The LED lighting unit of claim 1, wherein the first LED assembly and the second LED assembly are spaced 180°

apart relative to a center of the tubular housing and are oriented to face one another.

3. The LED lighting unit of claim 1, wherein the first LED assembly and the second LED assembly are spaced 180°

apart relative to a center of the tubular housing and are oriented to face a direction offset from a radius of the tubular housing.

4. The LED lighting unit of claim 1, further comprising:

a reflecting surface extending longitudinally in the interior of the tubular housing, spaced apart from an interior surface of the tubular housing and facing at least one of the first LED assembly and the second LED assembly.

11. The LED lighting unit of claim 1, further comprising:

a first heat sink attached to the first LED assembly; and

a second heat sink attached to the second LED assembly.

12. The LED lighting unit of claim 1, wherein the tubular housing includes one tube portion having a circular cross-section.

13. The LED lighting unit of claim 1, wherein the first LED assembly and the second LED assembly each include a circuit board supporting a respective plurality of LEDs.

5. A LED lighting unit for replacing a conventional fluorescent bulb of a conventional fluorescent lighting fixture comprising:

a tubular housing including at least one tube portion;

a first LED assembly including a plurality of LEDs, the first LED assembly located along a first longitudinal length of the tubular housing and oriented to face an interior of the tubular housing;

a second LED assembly including a plurality of LEDs, the second LED assembly attached to a second longitudinal length of the tubular housing and oriented to face the interior of the tubular housing; and

a reflecting surface inside the tubular housing, wherein the reflecting surface spans a diameter of an interior surface of the at least one tube portion and has a first concave side and a second concave side, and the first LED assembly faces the first concave side and the second LED assembly faces the second concave side.

6. The LED lighting unit of claim 5, further comprising a lip that projects from a midpoint on the first concave side of the reflecting surface to direct light toward a perimeter of the first LED assembly.

7. The LED lighting unit of claim 6, wherein the reflecting surface includes a diffusing surface.

8. The LED lighting unit of claim 6, wherein the reflecting surface includes a bend located at a junction of the reflecting surface and the at least one tube portion, with the bend being angled to direct light toward a perimeter of the first LED assembly.

9. A LED lighting unit for replacing a conventional fluorescent bulb of a conventional fluorescent lighting fixture comprising:

a tubular housing including at least one tube portion;

a first LED assembly including a plurality of LEDs, the first LED assembly located along a first longitudinal length of the tubular housing and oriented to face an interior of the tubular housing; and

a second LED assembly including a plurality of LEDs, the second LED assembly attached to a second longitudinal length of the tubular housing and oriented to face the interior of the tubular housing, wherein each tube portion has an arc-shaped cross-section, a transparent outer layer, a diffusing interior layer, and is made of at least one of polycarbonate, acrylic and glass.

10. The LED lighting unit of claim 9, further comprising wherein the at least one tube portion comprises:

a first semicircular tube portion attached to the first LED assembly and the second LED assembly; and

a second semicircular tube portion attached to the first LED assembly and the second LED assembly.

14. An LED lighting unit for replacing a conventional fluorescent tube of a conventional fluorescent lighting fixture comprising:

a tubular housing including at least one tube portion;

at least one LED assembly including a plurality of LEDs, each LED assembly mounted to a longitudinal length of the tubular housing and oriented to emit light parallel to a tangent of the tubular housing; and

a light pipe associated with each LED assembly and curving inside at least a portion of the tubular housing.

15. The LED lighting unit of claim 14, wherein each LED assembly includes a circuit board mounted to extend radially into an interior of the tubular housing to form a radially-extending mounting surface for LEDs mounted thereon.

16. The LED lighting unit of claim 14, wherein each LED assembly includes a side-emitting LED.

17. The LED lighting unit of claim 14, wherein a surface of the light pipe includes a plurality of light extracting structures.

18. The LED lighting unit of claim 17, wherein the a density of the light extracting structures varies over an arc of the light pipe.

19. The LED lighting unit of claim 14, further comprising:

a plurality of light extracting structures on an interior surface of the tubular housing; and

a diffusing layer on an exterior surface of the tubular housing.

20. The LED lighting unit of claim 15, further comprising:

a plurality of LED assemblies spaced about the circumference of the tubular housing; and

wherein

an entrance of each light pipe is radially-oriented and facing the radially-extending mounting surface of a respective circuit board.