LED-based planar light source

• US 6,799,865 B2
• Filed: 07/19/2002
• Issued: 10/05/2004
• Est. Priority Date: 07/31/2001
• Status: Expired due to Term

• Current Assignee: Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen mbH (Ams-Osram AG)
• Original Assignee: Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen mbH (Ams-Osram AG)
• Inventors: Zwaschka, Franz, Ellens, Andries, Schliep, Karl-Peter
• Primary Examiner(s): Cariaso, Alan
• Assistant Examiner(s): Alavi, Ali
• Application Number:
  US10/199,932
• Publication Number:
  US 20030026096A1
• Time in Patent Office: 809 Days
• Field of Search: 313/502, 313/503, 313/504, 313/512, 257/89, 257/98, 257/99, 257/100, 257/103, 362/231, 362/240, 362/293, 362/800
• US Class Current: 362/240
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

The planar light source (1) uses the principle of RGB mixing, the radiation of UV diodes (5) arranged in a planar fashion being converted by means of phosphors (7) which emit in the red and green spectral regions. The blue component is added by blue-emitting LEDs (8) whose radiation is preferably launched as a lateral diode row (9).

Claims

1. LED-based planar light source utilizing the colour mixing principle, the radiation from dot-like UV-emitting diodes, arranged in a planar fashion, being converted into light of longer wavelength by means of conversion by at least one UV-absorbing phosphor, and this light being mixed with a blue component, wherein

the radiation of the UV diodes is absorbed by the at least one phosphor while the blue component is provided by at least one blue-emitting LED;

the UV-absorbing phosphors are applied to an optical conductor fitted at a spacing from the UV diodes, or to a transparent plate or are directly located on the individual dot-like UV-LEDs; and

the admixture of the blue component provided by the at least one blue-emitting LED is performed only after conversion of the UV-radiation.

2. Planar light source according to claim 1, wherein the radiation of the UV diodes is absorbed by red- and green-emitting phosphors in order to provide a white-emitting light source by utilizing the RGB principle.

3. Planar light source according to claim 1, wherein the radiation of the UV diodes is absorbed by a yellow-emitting phosphor in order to provide a white-emitting light source by utilizing the blue-yellow mixing principle.

4. Planar light source according to claim 1, wherein the radiation of the UV diodes is absorbed by one or a plurality of colour-emitting phosphors in order to provide a colour-emitting light source by utilizing the colour mixing principle.

5. Planar light source according to claim 1, wherein the UV-absorbing phosphors are applied to an optical conductor fitted at a spacing from the UV diodes, or to a transparent plate.

6. Planar light source according to claim 1, characterized in that the number of the blue-emitting LEDs is at most equal to the number of the UV diodes.

7. Planar light source according to claim 1, wherein the blue-emitting LEDs are arranged in a planar fashion.

8. Planar light source according to claim 1, wherein the blue-emitting LEDs are arranged in rows.

9. Planar light source according to claim 8, wherein a row of blue-emitting LEDs is arranged next to an array of UV diodes.

10. Planar light source according to claim 8, wherein at least two rows of blue-emitting LEDs are arranged next to edges of a surface of UV diodes.

11. Planar light source according to claim 1, wherein an GaN-based LED on a silicon carbide substrate is used as UV diode.

12. Planar light source according to claim 1, wherein the peak wavelength of the primary UV emission is at 300 to 420 nm, and the peak wavelength of the blue emission is at 430 to 490 nm, and the secondary emission of green and red phosphors has a peak wavelength of 510 to 560 or 590 to 680 nm.

13. Planar light source according to claim 1, wherein the absorption spectrum at least of the red phosphor overlaps at least partially with the emission spectrum of the blue LEDs.