Luminance enhancement apparatus and method

• US 20050265404A1
• Filed: 05/27/2005
• Published: 12/01/2005
• Est. Priority Date: 05/28/2004
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Ashdown, Ian
• Application Number:
  US11/140,654
• Publication Number:
  US 20050265404A1
• Time in Patent Office: Days
• US Class Current: 372/20
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H10K 2102/331 Nanoparticles used in non-emissive layers, e.g. in packaging layer
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/80 Constructional details
• CPC Class Codes: H10K 50/85 Arrangements for extracting light from the devices
• CPC Class Codes: H10K 50/856 comprising reflective means

Abstract

The present invention provides a luminance enhancement apparatus and method for use with light-emitting elements comprising a conversion system adjacent the light-emitting element for converting electromagnetic radiation of one or more wavelengths to alternate wavelengths. This conversion process can be enabled by the absorption of the one or more wavelengths by the conversion system and emission of the alternate wavelengths thereby. The conversion system comprises a predetermined surface relief pattern on the face opposite the light-emitting element to provide a means for reducing absorption of the emitted alternate wavelengths in addition to providing a means for reflection of the emitted alternate wavelengths from the conversion system with a reduced number of reflections, thereby enhancing the illumination provided by the light-emitting element. As the present invention operates on principles of increased surface area and self-excitation of the conversion materials through the use of a predetermined surface relief pattern, the present invention may be applied to both organic LEDs, phosphor-coated semiconductor LEDs, and light-emitting elements coated with a population of quantum dots embedded in a host matrix.

Claims

1. An illumination apparatus comprising:

a) one or more light-emitting elements that serve as a primary source of electromagnetic radiation; and

b) a conversion system positioned to interact with the electromagnetic radiation produced by the one or more light-emitting elements, said conversion system having a predetermined surface relief pattern on a face opposite the one or more light-emitting elements, said conversion system further including a conversion means for changing one or more wavelengths of the electromagnetic radiation from the one or more light-emitting elements to electromagnetic radiation having one or more alternate wavelengths;

wherein said one or more light-emitting elements are adapted for connection to a power source for activation thereof.

2. The illumination apparatus according to claim 1, wherein the predetermined surface relief pattern comprises a plurality of “

V”

shaped grooves or trapezoidal shaped grooves.

3. The illumination apparatus according to claim 2, wherein the grooves are defined by intersecting planes having an angle therebetween varying between 0 and 180 degrees.

4. The illumination apparatus according to claim 3, wherein the angle varies between 20 and 90 degrees.

5. The illumination apparatus according to claim 4 wherein the angle is 30 degrees.

6. The illumination apparatus according to claim 1, wherein the predetermined surface relief pattern comprises a plurality of conical shaped depressions.

7. The illumination apparatus according to claim 1, wherein the predetermined surface relief pattern comprises a plurality of pyramid shaped depressions, the pyramid shaped depressions having polygon bases with an even number of sides.

8. The illumination apparatus according to claim 7, wherein the pyramid shaped depressions are defined by intersecting planes having an angle therebetween varying between 0 and 180 degrees.

9. The illumination apparatus according to claim 8, wherein the angle varies between 20 and 90 degrees.

10. The illumination apparatus according to claim 9 wherein the angle is 30 degrees.

11. The illumination apparatus according to claim 7, wherein the polygon bases are hexagonal, octagonal, square, or rectangular.

12. The illumination apparatus according to claim 7, wherein said pyramid shaped depressions have parabolic curved sides.

13. The illumination apparatus according to claim 1, wherein the predetermined surface relief pattern comprises parabolic grooves.

14. The illumination apparatus according to claim 1, wherein the predetermined surface relief pattern is created by molding, embossing, or stamping.

15. The illumination apparatus according to claim 1, wherein the predetermined surface relief pattern is surface roughened on the face opposite the one or more light-emitting elements.

16. The illumination apparatus according to claim 1, further comprising a brightness enhancement film interposed between said conversion means and said one or more light-emitting elements, said brightness enhancement film providing a means for internally reflecting and refracting said electromagnetic radiation in directions substantially perpendicular to the predetermined surface relief pattern.

17. The illumination apparatus according to claim 16, further comprising an optical element interposed between the one or more light-emitting elements and said brightness enhancement film, said optical element for collecting and collimating the electromagnetic radiation.

18. The illumination apparatus according to claim 1, wherein said one or more light-emitting elements are organic light-emitting diodes.

19. The illumination apparatus according to claim 18, wherein the organic light-emitting diodes have a transparent glass or plastic substrate comprising the predetermined surface relief pattern.

20. The illumination apparatus according to claim 19, wherein the predetermined surface relief pattern is contiguous.

21. The illumination apparatus according to claim 19, wherein the predetermined surface relief pattern is segmented.

22. The illumination apparatus according to claim 1, wherein the one or more light-emitting elements are semiconductor light-emitting diodes and said conversion means comprises one or more layers of inorganic phosphorescent particles formed on the surface relief pattern.

23. The illumination apparatus according to claim 1, wherein said one or more light-emitting elements are quantum dot light-emitting diodes.

24. The illumination apparatus according to claim 23, wherein said conversion means is a quantum dot matrix molded, embossed or stamped with the predetermined surface relief pattern.

25. A method for enhancing luminance produced by one or more point light sources, said method comprising the steps of:

a) providing the one or more point light sources, each comprising a light-emitting element that serves as a primary source of electromagnetic radiation and includes a conversion system for changing one or more wavelengths of the electromagnetic radiation to one or more alternate wavelengths of electromagnetic radiation; and

b) forming a predetermined surface relief pattern on a face of the conversion system, said face being opposite the light-emitting element.

26. The method for enhancing luminance according to claim 25, wherein said step of forming said predetermined surface relief pattern is performed by molding, embossing or stamping.

27. The method for enhancing luminance according to claim 25, wherein said surface relief pattern is selected from the group comprising “

V”

shaped grooves, trapezoidal shaped grooves, parabolic grooves, conical shaped depressions, pyramid shaped depressions, and pyramid shaped depressions having parabolic curved sides.