Wide angle oval light emitting diode package

• US 8,350,370 B2
• Filed: 01/29/2010
• Issued: 01/08/2013
• Est. Priority Date: 01/29/2010
• Status: Active Grant

• Current Assignee: Cree Huizhou Solid State Lighting Company Limited (Smart Global Holdings Incorporated)
• Original Assignee: Cree Huizhou Opto Limited
• Inventors: Chan, Chi Keung, Zhikuan, Zhang, Lau, Yue Kwong, Liu, Hao, Fei, Xiang, Luo, Meigui, Sheng, Juzuo
• Primary Examiner(s): Sandvik, Benjamin
• Assistant Examiner(s): Wilson, Scott R
• Application Number:
  US12/657,935
• Publication Number:
  US 20110186865A1
• Time in Patent Office: 1,075 Days
• Field of Search: None
• US Class Current: 257/676
• CPC Class Codes: G09F 9/00 Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the variable information is permanently attached to a movable support G09F11/00; abacus G06C1/00; slide-rules G06G1/00
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 33/60 Reflective elements

Abstract

The present invention is directed to LED packages and LED displays utilizing LED packages where the peak emission of the LED displays can exhibit improved emission characteristics. In some embodiments the improved characteristics include a wider horizontal emission angle for the LED packages according to the present invention, which results in improved emission characteristics for the LED display such as a wider far field pattern. This provides improved picture intensity and quality when viewing the display at different horizontal viewing angles. Different embodiments also provide for improved emission characteristics for LED packages emitting different colors of light when viewing at different vertical angles. In one embodiment the red and green LED packages can have emission patterns that are substantially the same at different vertical viewing angles within a range. This helps the colors of the display appear consistent at those angles.

Claims

1. A light emitting diode (LED) display, comprising:

a plurality of LED packages each of which has a horizontal emission angle and a vertical emission angle, wherein said horizontal emission angle is greater than said vertical emission angle in at least some of said LED packages;

wherein each of said at least some of said LED packages comprises a reflective cup with an LED, said reflective cup comprising an opening that is larger for body emitting LEDs compared to reflective cups with similarly sized top emitting LEDs.

2. The LED display of claim 1, wherein each of said at least some LED packages comprises an oval shaped reflective cup.

3. The LED display of claim 2, wherein said oval shaped reflective cup is longer in one direction, with said longer direction horizontally aligned.

4. The LED display of claim 1, wherein each of said at least some LED packages comprises a reflective cup with an LED, said reflective cup having side reflective surfaces arranged to match the emission characteristics of said LED.

5. The LED display of claim 1, wherein at least some of said reflective cups have body emitting LEDs with a reflective opening of 80°

or more.

6. The LED display of claim 1, wherein at least some of said reflective cups have body emitting LEDs with a reflective opening of approximately 100°

.

7. The LED display of claim 1, wherein at least some of said reflective cups have top emitting LEDs with a reflective opening of 60°

or more.

8. The LED display of claim 1, wherein at least some of said reflective cups have top emitting LEDs with a reflective opening of approximately 80°

.

11. The LED display of claim 1, wherein each of said at least some LED packages comprises an oval shaped encapsulant.

12. The LED display of claim 1, wherein each of said at least some LED packages has an encapsulant that is wider in one direction than another, the encapsulant arranged with the wider direction horizontally aligned.

13. The LED display of claim 1, wherein said each of said at least some LED packages comprises a reflective cup embedded in an encapsulant, said reflective cup arranged in said encapsulant at a point that promotes angles of emission beyond 90°

.

14. The LED display of claim 1, further comprising a reflective cup heat spreader and wire bond heat spreader, each of which has thermal resistance of less than 190 K/W.

15. The LED display of claim 1, having a screen emission pattern with a horizontal far field pattern of emission greater than 90°

.

16. The LED display of claim 1, having a screen emission pattern with horizontal far field pattern of emission of approximately 115°

.

9. A light emitting diode (LED) display, comprising:

a plurality of LED packages each of which has a horizontal emission angle and a vertical emission angle, wherein said horizontal emission angle is greater than said vertical emission angle in at least some of said LED packages;

wherein each of said at least some of said LED packages comprises a reflective cup with an LED, said reflective cup comprising side reflective surfaces that are higher for top emitting LEDs compared to reflective cups with similarly sized body emitting LEDs.

10. The LED display of claim 9, wherein said reflective cups with top emitting LEDs have reflective side surfaces that are more than 50% higher than reflective cups with the same sized body emitting LEDs.

17. A light emitting diode (LED) package, comprising:

a lead frame at least partially embedded in an encapsulant, wherein said lead frame comprises a reflective cup with an LED, wherein said reflective cup and encapsulant are arranged to cause emission of LED light from said package with an emission angle in a first direction that is greater than the emission in a second direction;

wherein said reflective cup comprises an opening that is larger for body emitting LEDs compared to reflective cups with similarly sized top emitting LEDs.

18. The LED package of claim 17, wherein said first direction is perpendicular to said second direction.

19. The LED package of claim 17, mounted in an LED display, said first direction being horizontal and said second direction being vertical.

20. The LED package of claim 17, wherein each said reflective cup is oval shaped.

21. The LED package of claim 17, further comprising a body emitting LED in said reflective cup, said reflective cup having a reflective opening of 80°

or more.

22. The LED package of claim 17, wherein said reflective cup has a reflective opening of approximately 100°

.

23. The LED package of claim 17, further comprising a top emitting LED in said reflective cup, said reflective cup having a reflective opening of 60°

or more.

24. The LED package of claim 17, wherein said reflective cup has a reflective opening of approximately 80°

.

25. The LED package of claim 17, wherein said encapsulant is oval shaped.

26. The LED package of claim 17, wherein said encapsulant is oval shaped and is wider in a first direction compared to a direction perpendicular to said first direction, said LED package mounted in an LED display with the first direction horizontally aligned.

27. The LED display of claim 17, said each of said at least some LED packages comprises a reflective cup embedded in an encapsulant, said reflective cup arranged in said encapsulant at a point that promotes angles of emission beyond 90°

.

28. A light emitting diode (LED) package, comprising:

a lead frame with a reflective cup portion with a reflective cup and an LED, said lead frame further comprising a wire bond portion, said reflective cup portion comprising a reflective cup heat spreader arranged to spread heat generated by said LED, said heat spreader sized to have a thermal resistance of less than 168 K/W.

29. The LED package of claim 28, further comprising a wire bond heat spreader integral to said wire bond portion and sized to have a thermal resistance of less than 180 K/W.

30. The LED package of claim 28, wherein said reflective cup heat spreader is sized to have a thermal resistance of less than 120 K/W.

31. The LED package of claim 29, wherein said wire bond spreader is sized to have a thermal resistance of less than 120 K/W.

32. The LED package of claim 28, further comprising an encapsulant with said lead frame embedded in said encapsulant, wherein said lead frame is patterned to provide adhesion between said encapsulant and said lead frame.

33. A light emitting diode (LED) display, comprising:

a plurality of LED packages each of which has a horizontal emission angle and a vertical emission angle, wherein said horizontal emission angle is greater than said vertical emission angle in at least some of said LED packages, wherein said LED display produces a horizontal far field pattern wider than its vertical far field pattern;

wherein each of said at least some of said LED packages comprises a reflective cup with an LED, said reflective cup comprising an opening that is larger for body emitting LEDs compared to reflective cups with similarly sized top emitting LEDs.

34. A light emitting diode (LED) display, comprising:

a plurality of pixels, each of which comprises a plurality of LED packages emitting different colors of light, each of said LED packages having a horizontal emission angle and a vertical emission angle, wherein said horizontal emission angle is greater than said vertical emission angle, the emission pattern of each of said LED packages at different vertical viewing angles within a range of viewing angles being substantially the same;

wherein at least some of said LED packages comprise a reflective cup with an LED, said reflective cup comprising an opening that is larger for body emitting LEDs compared to reflective cups with similarly sized top emitting LEDs.

35. The LED display of claim 34, wherein said range of viewing angles is 0 to 30°

.