Light emitting device, display apparatus with an array of light emitting devices, and display apparatus method of manufacture

• US 6,657,382 B2
• Filed: 07/19/2001
• Issued: 12/02/2003
• Est. Priority Date: 07/21/2000
• Status: Expired due to Term

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Izuno, Kunihiro, Nagai, Yoshifumi, Fujiwara, Yuichi
• Primary Examiner(s): Patel, Ashok
• Application Number:
  US09/907,715
• Publication Number:
  US 20020039001A1
• Time in Patent Office: 866 Days
• Field of Search: 313/512, 313/502, 313/503, 313/504, 313/498, 313/116, 313/112, 313/113, 315/169.3, 345/36, 345/45, 345/76, 428/917, 428/690, 362/355, 362/310, 362/311, 362/800
• US Class Current: 313/512
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 24/45 of an individual wire connector
• 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 2924/12041 LED
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A light emitting device and display apparatus using a plurality of light emitting devices can drastically reduce contrast loss due to light from an external source. The light emitting device has (a) light emitting chip(s) and a first layer covering the light emitting chip(s). A second layer including a light scattering material Is provided at least over the first layer, and the surface of second layer has a plurality of protrusions which follow the topology of the light scattering material. The display apparatus is formed by disposing these light emitting devices In an array on a substrate.

Claims

1. A light emitting device comprising:

a light emitting chip;

a first layer covering the light emitting chip; and

a second layer including light scattering material, the second layer being provided at least over the first layer,

wherein the average thickness of the second layer is smaller than the average diameter of the light scattering material, and

wherein a surface of the second layer has a plurality of protrusions that follows the topology of the light scattering material.

2. A light emitting device as recited in claim 1, further comprising a package defining a cavity having a base, the light emitting chip being disposed on a surface at the base of the cavity, wherein the first layer is positioned at least within the cavity, and an upper surface of the first layer is a concave surface.

3. A light emitting device as recited in claim 2, wherein the second layer is positioned at least over the concave surface of the first layer, and wherein the film thickness of the second layer over the concave surface increases from the edges towards the center region.

4. A light emitting device as recited in claim 1, wherein the light scattering material has particulate form.

5. A light emitting device as recited in claim 1, wherein the light scattering material is comprised of dark pigment covered with transparent material.

6. A light emitting device as recited in claim 5, wherein the transparent material is insulating.

7. A light emitting device as recited in claim 4, wherein the average particle diameter of the particulate light scattering material included in the second layer is 10 μ

m to 20 μ

m, and the average film thickness of the second layer is 1 μ

m to 10 μ

m.

17. A light emitting device as recited in claim 1, wherein the light scattering material is incorporated within the second layer.

18. A light emitting device as recited in claim 1, wherein a portion of some of the light scattering material is exposed from the second layer.

8. A display apparatus comprising a plurality of light emitting devices disposed on a substrate with each of the light emitting devices comprising:

a light emitting chip;

a first layer covering the light emitting chip; and

a second layer including light scattering material, the second layer being provided at least over the first layer,

wherein the average thickness of the second layer is smaller than the average diameter of the light scattering material, and

wherein a surface of the second layer has a plurality of protrusions that follows the topology of the light scattering material.

9. A display apparatus as recited in claim 8, wherein each of the light emitting devices has a package with a cavity, the light emitting chip being disposed on a base of the cavity, wherein the first layer is positioned at least within the cavity, and an upper surface of the first layer is a concave surface.

10. A display apparatus as recited in claim 9, wherein the second layer is positioned at least over the concave surface of the first layer, and wherein the film thickness of the second layer over the concave surface increases from the edges towards the center region.

11. A display apparatus as recited in claim 8, wherein the light scattering material has particulate form.

12. A display apparatus as recited in claim 8, wherein the light scattering material is comprised of dark pigment covered with transparent material.

13. A display apparatus as recited in claim 12, wherein the transparent material is insulating.

14. A display apparatus as recited in claim 11, wherein the average particle diameter of the particulate light scattering material is 10 μ

m to 20 μ

m, and the average film thickness of the second layer is 1 μ

m to 10 μ

m.

15. A display apparatus as recited in claim 8, wherein the second layer is also provided over the upper surface of the substrate.

16. A display apparatus as recited in claim 8, wherein the light emitting devices are disposed on the substrate via conducting material, the conducting material being positioned at least outside the light emitting devices as viewed by an observer, and the surfaces of the conducting material positioned outside the light emitting devices being covered with the second layer.

19. A light emitting device as recited in claim 8, wherein the light scattering material is incorporated within the second layer.

20. A light emitting device as recited in claim 8, wherein a portion of some of the light scattering material is exposed from the second layer.