Light emitting diode arrays with improved light extraction

• US 20050225222A1
• Filed: 04/09/2004
• Published: 10/13/2005
• Est. Priority Date: 04/09/2004
• Status: Abandoned Application

• Current Assignee: Lamina Ceramics, Inc.
• Original Assignee: Lamina Ceramics, Inc.
• Inventors: Mazzochette, Joseph, Amaya, Edmar
• Application Number:
  US10/822,191
• Publication Number:
  US 20050225222A1
• Time in Patent Office: Days
• US Class Current: 313/46
• CPC Class Codes: F21K 9/68 Details of reflectors forming part of the light source
• CPC Class Codes: G09F 9/33 being semiconductor devices, e.g. diodes
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/00014 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 2924/01004 Beryllium [Be]
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/0102 Calcium [Ca]
• CPC Class Codes: H01L 2924/01025 Manganese [Mn]
• CPC Class Codes: H01L 2924/01057 Lanthanum [La]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/19041 being a capacitor
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

In accordance with the invention, an illumination device comprises a highly thermally conductive substrate having a surface, a plurality of light emitting diodes (LEDs) supported by the surface and arranged in an array to provide illumination. At least one reflective barrier at least partially surrounds each LED. The reflective barrier is shaped to reflect away from the LED light emitted by other LEDs in the array. Advantageously the substrate and reflective barrier are thermally coupled to a heat spreader to dissipate heat generated by the LEDs. The substrate preferably comprises an LTTC-M heat spreader, and the reflective thermal barriers preferably comprise metal ridges or cups.

Claims

1. An illumination device comprising:

a substrate having a surface and including a highly thermally conductive heat spreader;

a plurality of light emitting diodes (LEDs) supported by the surface, the LEDs arranged in an array to provide illumination;

at least one reflective barrier at least partially surrounding each LED, the reflective barrier shaped to reflect away from the LED light emitted by other LEDs in the array;

the LEDs and the reflective barrier thermally coupled to the heat spreader to dissipate heat generated by the LEDs and heat produced by light absorption.

2. The device of claim 1 wherein the substrate comprises an LTCC-M heat spreader.

3. The device of claim 1 wherein the at least one reflective barrier comprises a periodic array of troughs and reflective ridges, the ridges shaped to reflect away from an LED light from an LED in an adjacent trough.

4. The device of claim 1 wherein the at least one reflective barrier comprises a reflective ridge shaped to reflect away LED light from an adjacent LED.

5. The device of claim 1 wherein at least one reflective barrier comprises a cup substantially peripherally surrounding an LED to reflect light away from adjacent LEDs.

6. The device of claim 4 wherein the at least one reflective barrier comprises an array of cups, each cup substantially peripherally surrounding a respective LED to reflect light away from adjacent LEDs.

7. The device of claim 1 wherein the at least one reflective barrier comprises a plurality of reflective circular sectors arranged in a circle, each reflective sector shaped to reflect away light from other sectors in the array.

8. The device of claim 1 wherein the at least one reflective barrier comprises a cavity having reflective walls and one or more smoothly curved reflective edges formed by the cooling of molten metal.

9. The device of claim 1 wherein the at least one reflective barrier is shaped to provide directional illumination.