LED light pipe

• US 8,928,021 B1
• Filed: 06/18/2013
• Issued: 01/06/2015
• Est. Priority Date: 06/18/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: LuxVue Techonology Corporation (Apple Inc.)
• Inventors: Bibl, Andreas, McGroddy, Kelly
• Primary Examiner(s): TRAN, MINH LOAN
• Application Number:
  US13/920,925
• Publication Number:
  US 20140367711A1
• Time in Patent Office: 567 Days
• Field of Search: 257/98, 257/99, 257/100, 257/E33.072, 257/E33.073
• US Class Current: 257/98
• CPC Class Codes: G02B 6/0096 the lights guides being of the hollow type
• CPC Class Codes: H01L 2224/14 of a plurality of bump connectors
• CPC Class Codes: H01L 24/24 of an individual high density interconnect connector
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• 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 2924/12041 LED
• CPC Class Codes: H01L 2924/12044 OLED
• 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 33/58 Optical field-shaping elements

Abstract

A light emitting device and method of manufacture are described. In an embodiment, the light emitting device includes a micro LED device, a light pipe around the micro LED device to cause internal reflection of incident light from the micro LED device within the light pipe, and a wavelength conversion layer comprising phosphor particles over the light pipe. Exemplary phosphor particles include quantum dots that exhibit luminescence due to their size, or particles that exhibit luminescence due to their composition.

Claims

1. A light emitting device comprising:

a micro LED device mounted on a substrate;

a light pipe around the micro LED device; and

a wavelength conversion layer over the light pipe, the wavelength conversion layer comprising phosphor particles;

wherein the light pipe is designed to allow refraction of incident light from the micro LED device out of the light pipe toward the wavelength conversion layer, and to cause internal reflection and lateral spreading of incident light from the micro LED device within the light pipe.

2. The light emitting device of claim 1, wherein the micro LED device has a maximum width of 1 μ

m-100 μ

m.

3. The light emitting device of claim 1, wherein the light pipe is elongated dome shaped.

4. The light emitting device of claim 1, wherein a lateral length of the light pipe is greater than a thickness of the light pipe.

5. The light emitting device of claim 1, wherein the phosphor particles are quantum dots.

6. The light emitting device of claim 1, wherein the phosphor particles exhibit luminescence due to their composition and do not qualify as quantum dots.

7. The light emitting device of claim 1, wherein the phosphor particles are dispersed in a polymer or glass matrix.

8. The light emitting device of claim 1, wherein a refractive index of the light pipe is within 0.1 of a refractive index of the wavelength conversion layer.

9. The light emitting device of claim 8, wherein the light pipe and the wavelength conversion layer comprise the same matrix material.

10. The light emitting device of claim 1, wherein the light pipe is around a plurality of micro LED devices to cause internal reflection of incident light from the plurality of micro LED devices within the light pipe.

11. The light emitting device of claim 1, further comprising a reflective layer directly over the micro LED device.

12. The light emitting device of claim 11, wherein the reflective layer is over the wavelength conversion layer.

13. The light emitting device of claim 11, wherein the reflective layer is between the light pipe and the wavelength conversion layer.

14. The light emitting device of claim 1, further comprising a reflective layer beneath the micro LED device and the light pipe.

15. The light emitting device of claim 14, wherein the micro LED device is within a reflective bank structure.

16. The light emitting device of claim 1, comprising an array of micro LED devices, a corresponding array of light pipes around the array of micro LED devices, and an array of wavelength conversion layers over the array of light pipes.

17. The light emitting device of claim 16 wherein the array of wavelength conversion layers comprises multiple groups of wavelength conversion layers, with each group designed to emit a different color emission spectrum.

18. The light emitting device of claim 17, further comprising a plurality of pixels, each pixel comprising at least one wavelength conversion layer from each of the multiple groups of wavelength conversion layers.

19. The light emitting device of claim 1, further comprising:

an array of pixels, each pixel comprising a plurality of subpixels designed for different color emission spectra, wherein the plurality of subpixels comprises;

a first subpixel including;

a first micro LED device;

a first light pipe around the first micro LED device;

a first wavelength conversion layer comprising first phosphor particles over the first light pipe; and

a second subpixel including;

a second micro LED device;

a second light pipe around the second micro LED device;

a second wavelength conversion layer comprising second phosphor particles over the second light pipe; and

wherein the first and second micro LED devices have the same composition for the same emission spectrum, and the first and second phosphor particles are designed for different color emission spectra.

20. The light emitting device of claim 1, further comprising:

an array of pixels, each pixel comprising a plurality of subpixels designed for different color emission spectra, wherein the plurality of subpixels comprises;

a first subpixel including;

a first micro LED device;

a first light pipe around the first micro LED device;

a first wavelength conversion layer comprising first phosphor particles over the first light pipe; and

a second subpixel including;

a second micro LED device;

a second light pipe around the second micro LED device;

wherein a wavelength conversions layer comprising phosphor particles is not formed over the second light pipe.

21. The light emitting device of claim 1, further comprising:

an array of pixels, each pixel comprising a plurality of subpixels designed for different color emission spectra;

an array of light pipes corresponding to the array of pixels, each light pipe spanning the plurality of subpixels of a corresponding pixel.

22. The light emitting device of claim 21, further comprising a micro LED device mounted within each subpixel in each pixel.

23. The light emitting device of claim 21, further comprising a micro LED device within each light pipe, wherein a micro LED device is not mounted within every subpixel corresponding to a light pipe.

24. The light emitting device of claim 21, further comprising a plurality of different wavelength conversion layers designed for different color emission spectra formed over each light pipe where it spans over the plurality of subpixels of a corresponding pixel.