Illumination device having a tapered light guide

• US 9,448,353 B2
• Filed: 02/20/2015
• Issued: 09/20/2016
• Est. Priority Date: 01/30/2008
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Holman, Robert Louis, Sampsell, Matthew Brian
• Primary Examiner(s): Green, Tracie Y
• Application Number:
  US14/627,460
• Publication Number:
  US 20150168635A1
• Time in Patent Office: 578 Days
• US Class Current: 1/1
• CPC Class Codes: F21V 5/02 of prismatic shape F21V5/04 takes precedence
• CPC Class Codes: F21V 5/10 comprising photoluminescent material
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0008 the light being emitted at the end of the fibre
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0058 varying in density, size, shape or depth along the light guide
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0085 Means for removing heat created by the light source from the package heat extraction or cooling elements for semiconductor light sources in general H01L33/64
• CPC Class Codes: Y10T 156/1089 of discrete laminae to single face of additional lamina

Abstract

This disclosure provides systems, methods and apparatus for illumination devices. In one aspect, an illumination device having a longitudinal axis includes a light source and a light guide. The light guide has a peripheral edge, a transmissive illumination surface, a center portion, and an upper surface. The transmissive illumination surface is oriented perpendicular to the longitudinal axis and disposed between the center portion and the peripheral edge. The upper surface is oriented relative to the illumination surface to define an angle α therebetween. In some implementations, the angle α can be greater than 15 degrees, for example.

Claims

1. An illumination device, comprising:

a light source;

a tapered light guide including

a light input surface on an end of the light guide,

a light output surface extending away from the light input surface along a plane at an angle to the light input surface, and

an inclined surface opposite the light output surface, the inclined surface being at an angle α

, with respect to the light output surface, of less than 15 degrees, the light source and the tapered light guide aligned such that light emitted from the light source propagates into the light guide through the input edge surface and exits the light guide through the light output surface;

an optical layer coupled to the light output surface of the light guide, the optical layer including at least one light redirecting element; and

a light reflecting layer adjacent to the inclined surface such that the inclined surface is located between the light reflecting surface and the light output surface, wherein the light reflecting layer is configured to reflect the light emitted from the light source towards the light output surface into the tapered light guide.

2. The illumination device of claim 1, wherein the light reflecting layer is spaced apart from the inclined surface by a gap.

3. The illumination device of claim 2, wherein the gap includes air.

4. The illumination device of claim 2, wherein the gap includes a dielectric.

5. The illumination device of claim 2, wherein the gap includes a material having an index of refraction that is less than an index of refraction of the light guide.

6. The illumination device of claim 1, wherein, light exiting the light guide through the light output surface is collimated and the optical layer is configured to redirect light exiting the light output surface along a desired direction.

7. The illumination device of claim 1, further comprising a light coupling system between the light source and the light input surface.

8. The illumination device of claim 7, wherein the light coupling system includes an angle transforming reflector.

9. The illumination device of claim 7, wherein the light coupling system includes an etendue preserving reflector.

10. The illumination device of claim 7, wherein the light coupling system includes a curved reflector.

11. The illumination device of claim 7, wherein the light coupling system includes a light guiding pipe.

12. The device of claim 1, wherein the light source includes one or more light emitting diodes (LEDs).

13. The device of claim 1, wherein the light source includes an array of LEDs.

21. The device of claim 1, wherein the light reflecting layer is parallel to the inclined surface.

14. A method of manufacturing an illumination device, the method comprising:

providing a light source;

providing a tapered light guide including

a light input surface on an end of the light guide,

a light output surface extending away from the light input surface along a plane at an angle to the light input surface, the light guide configured such that light propagating in the light guide exits through the light output surface; and

an inclined surface opposite the light output surface, the inclined surface being at an angle α

with respect to the light output surface of less than 15 degrees;

aligning the light source and the tapered light guide such that light emitted from the light source propagates into the light guide through the input edge surface;

coupling an optical layer to the light output surface of the light guide, the optical layer including at least one light redirecting element; and

providing a light reflecting layer adjacent the inclined surface, wherein the light reflecting layer is configured to reflect the light emitted from the light source to the light output surface into the tapered light guide.

15. The method of claim 14, further comprising providing a light coupling system between the light source and the light input surface.

16. The method of claim 15, wherein the light coupling system includes an angle transforming reflector.

17. The method of claim 15, wherein the light coupling system includes an etendue preserving reflector.

18. The method of claim 15, wherein the light coupling system includes a curved reflector.

19. The method of claim 14, wherein the light source includes one or more light emitting diodes (LEDs).

20. The method of claim 14, wherein the light reflecting layer is spaced apart from the inclined surface by a gap.