Light-emitting device

• US 7,378,792 B2
• Filed: 10/31/2006
• Issued: 05/27/2008
• Est. Priority Date: 08/16/2006
• Status: Expired due to Fees

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Chao, Chu Li, Chi, Jim Yong, Huang, Chen Yang, Chu, Cheng Wei
• Primary Examiner(s): Patel; Ashok
• Application Number:
  US11/554,891
• Publication Number:
  US 20080042546A1
• Time in Patent Office: 574 Days
• Field of Search: 313/495
• US Class Current: 313/512
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 1/005 made of photonic crystals or photonic band gap materials photonic band-gap structures or photonic lattices in integrated optics G02B6/1225; photonic band-gap structures or photonic lattices in optical fibres G02B6/02295
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A light-emitting device of high light extraction efficiency comprises a first substrate, a light-emitting chip positioned on the first substrate and configured to emit light beams, a fluorescent material positioned on the light-emitting chip, a photonic crystal positioned on the fluorescent material and a reflector positioned on the photonic crystal and configured to reflect the light beam to the fluorescent material. The first substrate is preferably a metallic cup, and the light-emitting chip is positioned at the bottom of the metallic cup. The photonic crystal includes a second substrate and a plurality of protrusions positioned on the second substrate. Each of the protrusions includes a bottom end positioned on the second substrate and a tip portion smaller than the bottom end. The plurality of protrusions can be triangular pillars, semicircular pillars, sinusoid pillars, pyramids, or cones.

Claims

1. A light-emitting device, comprising:

a first substrate;

at least one light-emitting chip positioned on the first substrate for emitting light beams;

a fluorescent material positioned on the light-emitting chip;

a photonic crystal positioned on the fluorescent material such that the light beams emitted by the light-emitting chip must first pass through the fluorescent material before reaching the photonic crystal; and

a reflector positioned on the photonic crystal and configured to reflect the light beams to the fluorescent material.

2. The light-emitting device as claimed in claim 1, wherein the photonic crystal comprises:

a second substrate; and

a plurality of protrusions positioned on the second substrate.

3. The light-emitting device as claimed in claim 2, wherein the second substrate is made of material selected from the group consisting essentially of glass and plastic.

4. The light-emitting device as claimed in claim 2, wherein the protrusion comprises:

a bottom end positioned on the second substrate; and

a tip portion smaller than the bottom end.

5. The light-emitting device as claimed in claim 2, wherein at least some of the protrusions in the plurality of protrusions have a shape selected from the group consisting of triangular pillars, semicircular pillars, sinusoid pillars, triangular pyramids, quadrangular pyramids, and cones.

6. The light-emitting device as claimed in claim 2, wherein the plurality of protrusions are arranged in a configuration selected from at least one member of the group consisting of rectangular, a triangular, a hexagonal, and a random manner.

7. The light-emitting device as claimed in claim 1, wherein the reflector comprises:

a third substrate;

a plurality of first films and second films alternately laminated; and

wherein the plurality of first films and second films is disposed on the third substrate.

8. The light-emitting device as claimed in claim 7, wherein the third substrate is made of material selected from the group consisting essentially of glass and plastic.

9. The light-emitting device as claimed in claim 7, wherein the refractive index of the first film is larger than the refractive index of the second film.

10. The light-emitting device as claimed in claim 7, wherein the first film is made of material selected from the group consisting of titanium oxide, tantalum oxide, niobium oxide, cerium oxide and zinc sulphide.

11. The light-emitting device as claimed in claim 7, wherein the second film is made of material selected from the group consisting of silicon oxide, silicon nitride, aluminum oxide and magnesium fluoride.

12. The light-emitting device as claimed in claim 10 further comprising an air gap disposed between the photonic crystal and the reflector.

13. The light-emitting device as claimed in claim 1, wherein the first substrate is a metallic cup.