Light emitting diode

• US 6,943,379 B2
• Filed: 03/24/2003
• Issued: 09/13/2005
• Est. Priority Date: 04/04/2002
• Status: Expired due to Fees

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Kawano, Hitomi, Suehiro, Yoshinobu, Takahashi, Yuji, Hirano, Atsuo, Takashima, Tatsuya
• Primary Examiner(s): Pham, Hoai
• Assistant Examiner(s): Ha, Nathan W.
• Application Number:
  US10/394,589
• Publication Number:
  US 20030230757A1
• Time in Patent Office: 904 Days
• Field of Search: 257 99-104, 257/678, 438/22, 438/37
• US Class Current: 257/99
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/01046 Palladium [Pd]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material

Abstract

In a light emitting diode, a blue light emitting element is mounted on a base having a cup through a phosphor-containing mount so that the light emitting element is located within the cup and is mounted on the bottom of the cup through the phosphor-containing mount. The light emitting diode includes a light emitting element and a p electrode. By virtue of the above construction, blue light emitted from the light emitting element can be reflected from the lower surface of the p electrode without being radiated directly from the upper surface of the light emitting element to the outside of the light emitting diode. As a result, the blue light emitted from the light emitting element can be efficiently mixed with yellow light given off from the phosphor in the phosphor-containing mount to provide white light which is radiated to the outside of the light emitting diode with high efficiency. The white light can be perceived by a viewer to be uniformly radiated from the light radiating surface of the light emitting diode.

Claims

1. A light emitting diode comprising:

a base;

a light emitting element comprising a compound semiconductor provided on the base;

a mount which is provided between the base and the light emitting element to bond the base to the light emitting element, said mount including a phosphor which absorbs light emitted from the light emitting element and gives off light having a wavelength different from the absorbed light; and

a phosphor-mixed layer that is provided on a light emitting surface side of the light emitting element and a side surface of the light emitting element and includes a phosphor which absorbs light emitted from the light emitting element and gives off light having a wavelength different from the absorbed light,

wherein a concentration of the phosphor in the phosphor-mixed layer is lower than a concentration of the phosphor in the mount.

2. The light emitting diode according to claim 1, wherein a reflector is provided on the light emitting surface side of the light emitting element so as to face the light emitting element to reflect the light emitted from the light emitting element before radiation of the light to an outside of the light emitting diode.

3. The light emitting diode according to claim 2, wherein a light shielding sheet comprising at least one opening is provided on the emitted light viewing surface side of the light emitting element as viewed from the base side of the light emitting element.

4. The light emitting diode according to claim 1, wherein the base comprises a pair of leads for supplying electric power to the light emitting element.

5. The light emitting diode according to claim 1, wherein the light emitting element, the mount, and the phosphor-mixed layer are sealed with a light transparent resin which is molded in a lens form as a whole.

6. The light emitting diode according to claim 1, wherein the light emitting element, the mount, and the phosphor-mixed layer are sealed with a light transparent resin which is molded to form a reflecting surface in such a shape that a part of a parabola, of which a focal point includes the light emitting surface of the light emitting element with an axis of symmetry being a horizontal direction, is rotated an a vertical direction.

7. The light emitting diode according to claim 1, wherein the light emitting element comprises a gallium nitride compound semiconductor which emits blue light.

8. The light emitting diode according to claim 1, wherein the phosphor comprises cerium-doped yttrium-aluminum-garnet which absorbs blue light and emits yellow light.

9. A light emitting diode comprising:

a base;

a light emitting element comprising a compound semiconductor provided on the base;

a mount which is provided between the base and the light emitting element to bond the base to the light emitting element, said mount including a phosphor which absorbs light emitted from the light emitting element and gives off light having a wavelength different from the absorbed light; and

a light-nontransparent conductive layer which is provided in an emitted light viewing surface side of said light emitting element,

wherein said light-nontransparent conductive layer reflects substantially all light emitted in a direction of said emitted light viewing surface side of said light emitting element from a light emitting layer of the light emitting element toward the mount, and

wherein said light emitted from said light emitting layer of the light emitting element, in said direction of said emitted light viewing surface side of said light emitting element, is transmitted other than directly above the light emitting element.

10. The light emitting diode according to claim 9, wherein the base comprises a metallic mount lead provided with a reflector for reflecting the light emitted from the light emitting element toward the emitted light viewing surface side.

11. The light emitting diode according to claim 9, wherein the conductive layer comprises a p electrode including at least one of a metal and an alloy of at least two metals selected from a group consisting of rhodium (Rh), gold (Au), platinum (Pt), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), cobalt (Co), magnesium (Mg), palladium (Pd), vanadium (V), manganese (Mn), bismuth (Bi), tin (Sn), and rhenium (Re).

12. The light emitting diode according to claim 11, wherein the p electrode is wire bonded directly to the base.

13. The light emitting diode according to claim 9, wherein a p electrode is provided on a whole surface of a p-type layer in the light emitting element.

14. The light emitting diode according to claim 9, wherein the light emitting element comprises a gallium nitride compound semiconductor which emits blue light.

15. The light emitting diode according to claim 14, wherein the phosphor comprises cerium-doped yttrium-aluminum-garnet which absorbs blue light and gives off yellow light.

16. The light emitting diode according to claim 9, wherein the light emitting element, the mount, and the conductive layer are sealed with a light transparent resin which is molded in a lens form as a whole.

17. The light emitting diode according to claim 9, wherein the base comprises:

an insulating board with a lead pattern being formed on the upper and lower sides thereof; and

a reflector for reflecting the light emitted from the light emitting element toward the emitted light viewing surface side, the reflector being provided on the insulating board so as to surround the light emitting element.

18. The light emitting diode according to claim 17, wherein a light transparent resin for sealing the light emitting element, the mount, and the conductive layer is provided in a space within the reflector.

19. The light emitting diode according to claim 9, wherein the light-non-transparent conductive layer comprises a p electrode including a shape that is substantially equal to a shape of a light emitting layer of the light emitting element such that light emitted from the light emitting element is substantially incident to the mount.

20. The light emitting diode according to claim 9, wherein said light-nontransparent conductive layer comprises at least one of a continuous light-nontransparent conductive layer and a uniform light-nontransparent conductive layer.

21. The light emitting diode according to claim 9, wherein a thickness of said light-nontransparent conductive layer comprises a predetermined thickness that prevents light emitted from said light emitting layer of said light emitting element from transmitting through said light-nontransparent conductive layer.

22. A light emitting diode comprising:

a base;

a light emitting element comprising a compound semiconductor provided on the base;

a mount which is provided between the base and the light emitting element to bond the base to the light emitting element, said mount including a phosphor which absorbs light emitted from the light emitting element and gives off light having a wavelength different from the absorbed light; and

a light-nontransparent conductive layer which is provided in an emitted light viewing surface side of said light emitting element,

wherein said light-nontransparent conductive layer reflects substantially all light emitted in a direction of said emitted light viewing surface side of said light emitting element from a light emitting layer of the light emitting element toward the mount, and

wherein substantially all of said light emitted from said light emitting layer of the light emitting element is emitted in a direction other than said direction of said emitted light viewing surface side of said light emitting element.

23. A light emitting diode comprising:

a base;

a light emitting element comprising a compound semiconductor provided on the base;

a mount which is provided between the base and the light emitting element to bond the base to the light emitting element, said mount including a phosphor which absorbs light emitted from the light emitting element and gives off light having a wavelength different from the absorbed light; and

a light-nontransparent conductive layer which is provided in an emitted light viewing surface side of said light emitting element,

wherein said light-nontransparent conductive layer reflects substantially all light emitted in a direction of said emitted light viewing surface side of said light emitting element from a light emitting layer of the light emitting element toward the mount, and

wherein said light emitted from said light emitting layer of the light emitting element is emitted other than directly from said light emitting element in said direction of said emitted light viewing surface side of said light emitting element.

24. A light emitting diode comprising:

a base;

a light emitting element comprising a compound semiconductor provided on the base;

a mount which is provided between the base and the light emitting element to bond the base to the light emitting element, said mount including a phosphor which absorbs light emitted from the light emitting element and lives off light having a wavelength different from the absorbed light; and

a light-nontransparent conductive layer which is provided in an emitted light viewing surface side of said light emitting element,

wherein said light-nontransparent conductive layer reflects substantially all light emitted in a direction of said emitted light viewing surface side of said light emitting element from a light emitting layer of the light emitting element toward the mount, and

wherein light emitted from said light emitting layer is reflected downward by an entire back face of said light-nontransparent conductive layer.