Wide emitting lens for LED useful for backlighting

• US 20060102914A1
• Filed: 03/29/2005
• Published: 05/18/2006
• Est. Priority Date: 11/15/2004
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.), Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Harbers, Gerard, West, Robert Scott, Martin, Paul S., Basin, Grigoriy, Hendriks, Robert F. M., Konijn, Frans H., Smits, Willem H.
• Granted Patent: US 7,352,011 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0066 in the form of an LED array
• CPC Class Codes: G02B 19/0071 adapted to illuminate a complete hemisphere or a plane extending 360 degrees around the source
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

Lenses and certain fabrication techniques are described. A wide-emitting lens refracts light emitted by an LED die to cause a peak intensity to occur within 50-80 degrees off the center axis and an intensity along the center axis to be between 5% and 33% of the peak intensity. The lens is particularly useful in a LCD backlighting application. In one embodiment, the lens is affixed to the backplane on which the LED die is mounted and surrounds the LED die. The lens has a hollow portion that forms an air gap between the LED die and the lens, where the light is bent towards the sides both at the air gap interface and the outer lens surface interface. The lens may be a secondary lens surrounding an interior lens molded directly over the LED die.

Claims

1. A light emitting diode (LED) structure comprising:

an LED die having a center axis; and

a lens fixed with respect to the LED die, the lens refracting light emitted by the LED die to cause a peak intensity to occur within 50-80 degrees off the center axis and an intensity along the center axis to be between 5% and 33% of the peak intensity.

2. The structure of claim 1 wherein light emitted from the LED structure has a brightness profile, the lens not creating any sharp intensity transitions around the center axis.

3. The structure of claim 1 wherein the peak intensity occurs within 70-80 degrees off the center axis.

4. The structure of claim 1 wherein the peak intensity occurs within 70-80 degrees off the center axis and the intensity along the center axis is 5-15% of the peak intensity.

5. The structure of claim 1 wherein the lens comprises an aspherical outer surface and an aspherical dome shaped inner surface.

6. The structure of claim 1 wherein the lens comprises an aspherical outer surface with a total internal reflection (TIR) portion for reducing light intensity near the center axis.

7. The structure of claim 1 wherein the lens has a hollow portion for forming a low index of refraction material gap between the LED die and the lens, the gap creating a refractive interface that bends light away from the center axis.

8. The structure of claim 7 wherein the gap contains air as the low index of refraction material.

9. The structure of claim 1 wherein the lens is a secondary lens, the structure further comprising a first lens between the LED die and the secondary lens.

10. The structure of claim 9 wherein the first lens is generally hemispherical.

11. The structure of claim 9 wherein the first lens is a lens molded directly over the LED die and encapsulates the LED die.

12. The structure of claim 9 wherein there is a gap between the first lens and the secondary lens, the gap creating a refractive interface that bends light away from the center axis.

13. The structure of claim 12 wherein the gap is a dome shaped air gap.

14. The structure of claim 9 wherein the first lens is silicone and the secondary lens is plastic.

15. The structure of claim 1 further comprising:

a submount on which the LED die is mounted;

a printed circuit board on which the submount is mounted;

wherein the lens directly contacts the printed circuit board and surrounds the submount.

16. The structure of claim 1 further comprising:

a submount on which the LED die is mounted;

a printed circuit board on which the submount is mounted;

wherein the lens directly contacts the submount and surrounds the LED die.

17. The structure of claim 1 wherein the lens has a pattern molded into its surface for affecting an emitted light pattern.

18. The structure of claim 17 wherein the pattern comprises a Fresnel lens, a diffraction grating, a binary pattern, pyramids, or cones.

19. The structure of claim 1 further comprising:

a backlight incorporating the LED die and lens; and

a liquid crystal display panel for being illuminated by the backlight.

20. A light emitting diode (LED) structure comprising:

an LED die having a center axis;

a first lens encapsulating the LED die; and

a secondary lens surrounding the first lens and LED die, the secondary lens having a hollow portion forming an air gap between the first lens and the secondary lens, the gap creating a refractive interface that bends light away from the center axis.

21. The structure of claim 20 wherein the secondary lens and air gap refract light emitted by the LED die to cause a peak intensity of light emitted by the LED structure to occur within 50-80 degrees off the center axis and an intensity along the center axis to be between 5% and 33% of the peak intensity.

22. The structure of claim 20 wherein the gap is dome shaped.

23. The structure of claim 20 wherein the first lens is a lens molded directly over the LED die.

24. A light emitting diode (LED) structure comprising:

an LED die;

a submount on which the LED die is mounted;

a printed circuit board on which the submount is mounted; and

a lens fixed with respect to the LED die, the lens refracting light emitted by the LED die, wherein the lens directly contacts the printed circuit board and surrounds the submount.

25. The structure of claim 24 wherein the lens is a secondary lens, the structure further comprising a first lens between the LED die and the secondary lens.

26. The structure of claim 25 wherein the first lens is generally hemispherical.

27. The structure of claim 25 wherein the first lens is a lens molded directly over the LED die and encapsulates the LED die.

28. A method for forming light emitting diode (LED) structure comprising:

providing an LED die having a center axis;

molding a first lens directly over the LED die to encapsulate the LED die; and

affixing a secondary lens over the first lens, the secondary lens having a hollow portion forming an air gap between the first lens and the secondary lens, the gap creating a refractive interface that bends light away from the center axis,

the secondary lens refracting light emitted by the LED die to cause a peak intensity to occur within 50-80 degrees off the center axis and an intensity along the center axis to be between 5% and 33% of the peak intensity.