Light emitting diode emitting red, green and blue light

• US 5,952,681 A
• Filed: 11/24/1997
• Issued: 09/14/1999
• Est. Priority Date: 11/24/1997
• Status: Expired due to Term

• Current Assignee: Solidlite Corp.
• Original Assignee: Hsing Chen
• Inventors: Chen, Hsing
• Primary Examiner(s): Tran, Minh Loan
• Application Number:
  US08/977,654
• Time in Patent Office: 659 Days
• Field of Search: 257/89, 257/98, 257/88, 257/90
• US Class Current: 257/89
• CPC Class Codes: H01L 27/153 in a repetitive configuration, e.g. LED bars
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials

Abstract

A multicolor light emitting diode (MLED) is disclosed which can emit various different colored light at the same time. A R, G, B three color LED is formed in a common crystalline granule (chip), with an ultra violet light crystalline granule formed by GaN grown on a sapphire substrate, and the finished products are all transparent. The surrounding of the granule is plated with an insulated layer and then a reflection layer. The light excited by the light granule is emitted either from the front or the back surface of LED. After the excited light has passed through a wave length converting layer, it can be converted to a colored visible light. The entire crystalline granule may be completely formed into an ultra violet or blue light chip, with wave length converting layers so that the chip can emit red, green and blue colors.

Claims

1. A multicolor LED comprising:

a) at least three light emitting diode chips on a transparent substrate, each light emitting diode chip having;

a P type electrode;

a N type electrode;

a reflection layer to direct light produced by the light emitting diode chip in a predetermined light emitting direction; and

,

b) at least two wavelength converting layers located in the predetermined light emitting direction of the light from at least two of the light emitting diode chips, whereby light having at least three different colors is emitted from the LED.

2. The multicolor LED as claimed in claim 1, wherein said light emitting diode chips comprise three blue light LED chips on said substrate to form one colored unit wherein said at least two wavelength converting layers are associated with two of the three blue light LED chips enabling the colored unit to emit red, green and blue light.

3. The multicolor LED as claimed in claim 2, wherein the predetermined light emitting direction is through back surfaces of the blue light LED chips wherein each of said three blue light LED chips further comprise an insulation layer on which is formed said reflection layer;

each of said P type electrodes comprises a reflective metallic layer; and

wherein said at least two wavelength converting layers comprise red and green wavelength converting layers on a bottom surface facing the substrate to emit red, green and blue light respectively.

4. The multicolor LED as claimed in claim 3, wherein each of said three blue light LED chips comprise an insulating layer on which is formed said reflection layer, wherein said P type electrode comprises a reflective metallic layer, said wavelength converting layers located on bottom surfaces of two of said three blue light LED chips and comprising red and green wavelength converting layers respectively to emit blue-red and blue-green colored light respectively, and further comprising a blue light filter layer on each of said red and said green wavelength converting layers for obtaining red and green lights respectively, in addition to the blue light excited by said blue light LED chip being emitted out of a back surface of said LED.

5. The multicolor LED as claimed in claim 4, further comprising a transparent sealing gel coated on a surface of said wavelength converting layer to protect said wavelength converting layer.

6. The multicolor LED as claimed in claim 2, wherein said three blue light LED chips have the predetermined light emitting direction through front surfaces each of said three blue light LED chips further comprising an insulation layer on which is formed said reflection layer;

a second reflection layer formed on a bottom surface of the substrate;

said P type electrode comprising a transparent electrode, said at least two wavelength converting layers located on two of said three blue light LED chips P type electrodes, and comprising red and green wavelength converting layers respectively to emit blue-red light and blue-green light respectively, and further comprising a blue light filter layer formed on each of said red and said green wavelength converting layer to filter out blue light, thereby obtaining red and green lights, in addition to the blue light excited by said blue light LED chip.

7. The multicolor LED as claimed in claim 1, wherein said light emitting diode chips comprise three ultra violet light emitting diode chips and further comprising a wavelength converting layer located in the predetermined light emitting direction of the light from the three ultra violet light emitting diode chips.

8. The multicolor LED as claimed in claim 7, wherein said reflection layer is comprised of a material having both reflective and insulative properties.

9. The multicolor LED as claimed in claim 7, wherein the predetermined light emitting direction is through front surfaces of the ultra violet light emitting diode chips, wherein said ultra violet light emitting diode chips each further comprise an insulation layer with said reflection layer being formed thereon;

a second reflection layer formed on a bottom surface of the substrate; and

wherein said P type electrode comprises a transparent electrode with said wavelength converting layer coated thereon whereby three colors of light are emitted out of said LED.

10. The multicolor LED as claimed in claim 7, wherein the wavelength converting layers comprise red, green, and blue wavelength converting layers one wavelength converting layer formed on each of said three ultra violet light emitting diode chips to enable the LED to emit red, green and blue light.

11. The multicolor LED as claimed in claim 10, wherein the predetermined light emitting direction is through front surfaces of the ultra violet light emitting diode chips, wherein each of said three ultra violet light emitting diode chips further comprise an insulation layer with said reflection layer formed thereon;

a second reflection layer formed on a bottom surface of the substrates;

said P type electrode comprises a transparent electrode; and

said wavelength converting layers comprise red, green and blue wavelength converting layers for emitting red, green and blue light respectively.

12. The multicolor LED as claimed in claim 10, wherein the predetermined light emitting direction is through back surfaces of the ultra violet light emitting diode chips, wherein each of said three ultra violet light emitting diode chips further comprise an insulation layer with said reflection layer formed thereon;

and wherein said P type electrode comprises a reflective metallic layer, said wavelength converting layers comprising red, green and blue wavelength converting layers on a bottom surface facing said substrate to emit red, green and blue light respectively.

13. The multicolor LED as claimed in claim 12, further comprising a transparent sealing gel coated on a surface of each of said wavelength converting layers to protect said wavelength converting layers.