Light emitting diode and method for fabricating the same

• US 20050174779A1
• Filed: 05/16/2003
• Published: 08/11/2005
• Est. Priority Date: 05/17/2002
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: CCS Corporation
• Inventors: Yoneda, Kenji, Inagaki, Yasuhiko, Amano, Takahiro
• Granted Patent: US 7,213,945 B2
• Time in Patent Office: Days
• US Class Current: 362/294
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/48091 Arched
• 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 33/54 having a particular shape
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

Alight emitting diode unit comprises a light emitting element D1, a base 1 having a heat dissipating member 12 that dissipates heat generated by the light emitting element D1, and a first lens 2 comprising a reflecting element 214 that reflects light R2 traveling outside of a predetermined angle among the emitted light R emitted by the light emitting element D1 and a refracting element F that refracts light R1 traveling inside of the predetermined angle among the emitted light R, each of which is formed integrally, with the first lens 2 mounted integrally on the base 1, and the emitted light R emitted from the light emitting element D1 is made to travel generally toward the same direction by the reflecting element 214 and the refracting element F.

Claims

1. A light emitting diode unit comprising:

a light emitting element,

a base having a heat dissipating member that dissipates heat generated by the light emitting element, and

a first lens comprising a reflecting element that reflects light traveling outside of a predetermined angle among the light emitted by the light emitting element and a refracting element that refracts light traveling inside of the predetermined angle among the light emitted by the light emitting element, each of which is integrally formed, with the first lens mounted integrally on the base, wherein the emitted light from the light emitting element is made to travel generally toward the same direction by the reflecting element and the refracting element.

2. The light emitting diode unit described in claim 1, and characterized in that the first lens is provided with an element protective portion that accommodates the light emitting element, and that a transparent member of resin fills the element protective portion.

3. The light emitting diode unit described in claim 1 or 2, and characterized in that the refracting element is a Fresnel lens comprising a convex lens portion arranged at the Fresnel lens center and multiple orbicular zone lens portions arranged concentrically around the convex lens portion.

4. The light emitting diode unit described in claim 3, and characterized in that a distance between each orbicular zone lens portion and the plane of the light emitting element, parallel to the optical axis, is set to increase for the orbicular zone lens portions located closer to the center.

5. The light emitting diode unit described in claim 4, wherein a refracting surface of each orbicular zone lens portion is made to be aspherical.

6. The light emitting diode unit described in claim 4 or 5, wherein an angle, between a connecting surface between the refracting surface of one orbicular zone lens portion and a refracting surface of the orbicular zone lens portion of its outer radial neighbor and the optical axis, is set to be identical with or smaller than an angle between the light traveling from an end of the light emitting element toward a bottom end of the connecting surface and the optical axis.

7. The light emitting diode unit described in claim 1, 2, 4 or 5, and characterized in that the base is so arranged that a heat conductive member whose coefficient of heat conductivity is larger than that of the heat dissipating member is arranged between the heat dissipating member and the light emitting element.

8. The light emitting diode unit described in claim 7, and characterized in that the base further comprises a wiring board mounted on a surface of the heat dissipating member and that a wire which supplies electric power to the light emitting element is directly connected to the wiring board.

9. The light emitting diode unit described in claim 1, 2, 4 or 5, and characterized in that the base comprises the heat dissipating member, a laminated insulating material covering over the heat dissipating member, and a wiring pattern arranged on the insulating material, that the light emitting element is a super high luminance type that can pass an electric current of not less than 250 mA wherein a boundary between the P-layer and the N-layer of the light emitting element is extremely close to a connecting surface to the wiring pattern, and that the light emitting element is mounted on the wiring pattern via a spacer having a predetermined thickness.

10. The light emitting diode unit described in claim 9, and characterized in that the spacer is electrically conductive.

11. The light emitting diode unit described in claim 10, and characterized in that a thermal expansion coefficient of the spacer has a value between a thermal expansion coefficient of the light emitting element and a thermal expansion coefficient of the heat dissipating member.

12. The light emitting diode unit described in claim 11, and characterized in that the thermal expansion coefficient of the spacer has a value between the thermal expansion coefficient of the light emitting element and the thermal expansion coefficient of the heat dissipating member, wherein the value is closer to the thermal expansion coefficient of the light emitting element than the thermal expansion coefficient of the heat dissipating member.

13. The light emitting diode unit described in claim 1, 2, 4, 5, 10, 11 or 12, and characterized in that a second lens that converges the light that travels toward generally the same direction is mounted on the first lens.

14. A method for manufacturing the light emitting diode unit described in claim 10, 11 or 12, and characterized by that the spacer is mounted on the base after the light emitting element is mounted on the spacer.

15. The method for manufacturing the light emitting diode unit described in claim 14, wherein the light emitting element is bonded on the spacer using a jointing material and the spacer is bonded on the base using a second jointing material that is different from the jointing material.

16. The method for manufacturing the light emitting diode unit described in claim 15, wherein the jointing material is an alloy of gold and tin and the second jointing material is solder.

17. A light emitting diode unit comprising:

a light emitting element having an optical axis; and

a first composite lens assembly having a side curved perimeter surface for reflecting off axis light from the light emitting element to be substantially parallel to the optical axis and a refracting surface mounted on the optical axis for refracting light from the light emitting element to be substantially co-parallel with the reflected light whereby the emitted light is substantially parallel rays.

18. The light emitting diode unit of claim 17 further including a second lens element mounted on the first composite lens assembly for converging the substantially parallel light rays from the first composite lens assembly.

19. The light emitting diode unit of claim 17 wherein the refracting surface is an aspheric surface.

20. The light emitting diode unit of claim 17 wherein the refracting surface is a Fresnel lens.

21. The light emitting diode unit of claim 18 wherein the light emitting element is mounted on a heat dissipating member with a reflective surface.

22. The light emitting diode unit of claim 21 wherein the heat dissipating member is mounted on a heat conductive sink member.

23. The light emitting unit of claim 17 wherein the light emitting element is mounted on a base member with a plurality of mounting apertures and the first composite lens assembly includes a plurality of mounting posts spaced to be complementary with the mounting apertures for securing the first composite lens assembly above the light emitting element.

24. The light emitting diode unit of claim 23 wherein a second lens element has a perimeter for encapsulating the perimeter surface of the first composite lens assembly, the second lens element converges the substantially parallel light rays from the first composite lens assembly.