Illumination unit having at least one LED as light source

• US 20030030368A1
• Filed: 07/03/2002
• Published: 02/13/2003
• Est. Priority Date: 07/16/2001
• Status: Active Grant

• Current Assignee: OSRAM OLED GMBH (Ams-Osram AG)
• Original Assignee: Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen mbH (Ams-Osram AG)
• Inventors: Ellens, Andries, Huber, Gunter, Kummer, Franz
• Granted Patent: US 6,657,379 B2
• Time in Patent Office: Days
• US Class Current: 313/503
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3852 Nitrides, e.g. oxynitrides, carbonitrides, oxycarbonitrides, lithium nitride, magnesium nitride
• CPC Class Codes: C04B 2235/3865 Aluminium nitrides
• CPC Class Codes: C04B 2235/3873 Silicon nitrides, e.g. silicon carbonitride, silicon oxynitride
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5481 Monomodal
• CPC Class Codes: C04B 2235/9661 Colour
• CPC Class Codes: C04B 35/597 based on silicon oxynitride, e.g. SIALONS
• CPC Class Codes: C04B 35/6265 involving reduction or oxidation
• CPC Class Codes: C04B 35/6268 characterised by the applied pressure or type of atmosphere, e.g. in vacuum, hydrogen or a specific oxygen pressure
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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

Abstract

An illumination unit having at least one LED as light source, the LED emitting primary radiation in the range from 300 to 485 nm, this radiation being partially or completely converted into longer-wave radiation by phosphors which are exposed to the primary radiation of the LED, in which unit the conversion takes place at least with the aid of a phosphor which emits yellow-orange with a peak emission wavelength at 540 to 620 nm and originates from the class of the Eu-activated sialons, the sialon corresponding to the formula M_p/2Si_12−p−qAl_p+qO_qN_16−q:Eu²⁺, where M=Ca individually or in combination with Mg or Sr, where q=0 to 2.5 and p=0 to 3.

Claims

1. An illumination unit having at least one LED as light source, the LED emitting primary radiation in the range from 300 to 485 nm, this radiation being partially or completely converted into longer-wave radiation by phosphors which are exposed to the primary radiation of the LED,

wherein conversion takes place at least with the aid of a phosphor which emits yellow-orange with a peak emission wavelength at 540 to 620 nm and originates from the class of the Eu-activated sialons, the sialon corresponding to the formula M_p/2Si₁₂₋

p−

qAl_p+qO_qN<sub>16−

q</sub>;

Eu²⁺, where M=Ca individually or in combination with at least one of the metals Sr or Mg, where q=0 to 2.5 and p=0.5 to 3.

2. The illumination unit as claimed in claim 1, wherein the Al is partially (up to 20 mol %) replaced by Ga.

3. The illumination unit as claimed in claim 1, wherein q<

1 and/or p=2 to 3 is selected.

4. The illumination unit as claimed in claim 1, wherein the mean grain diameter of the phosphor powder is selected to be between 0.5 and 5 μ

m.

5. The illumination unit as claimed in claim 1, wherein, to generate white light, the primary radiation emitted is in the wavelength region from 330 to 370 nm, the primary radiation emitted being exposed to at least two phosphors with an emission maximum in the blue (430 to 470 nm) and yellow-orange (in particular 545 to 590 nm) for conversion.

6. The illumination unit as claimed in claim 5, wherein the primary radiation is also exposed to at least one further phosphor, which emits either in the green (490 to 525 nm) or in the red (625 to 700 nm), for conversion.

7. The illumination unit as claimed in claim 6, wherein the further phosphor is a chlorosilicate or an Y- or Tb-based garnet.

8. The illumination unit as claimed in claim 1, wherein, to generate white light, the primary radiation emitted lies in the blue wavelength region of 430 to 470 nm, the primary blue radiation emitted being exposed to two phosphors with an emission maximum in the yellow-orange (545 nm to 590 nm) and in the green (490 to 525 nm).

9. The illumination unit as claimed in claim 1, wherein, to generate colored light, the primary radiation emitted lies in the blue wavelength region from 430 to 485 nm, the primary blue radiation emitted being exposed to a single phosphor having an emission maximum in the yellow-orange (545 nm to 590 nm).

10. The illumination unit as claimed in claim 9, wherein the proportion of the yellow-orange phosphor in the mixture is approximately 0.5 to 15%.

11. The illumination unit as claimed in claim 1, characterized in that the primary radiation source used is a light-emitting diode which emits at a short wavelength and is based in particular on Ga(In)N.

12. The illumination unit as claimed in claim 1, wherein the proportion of the Sr and/or Mg amounts to at most 40 mol % of the cation M.

13. The illumination unit as claimed in claim 1, wherein the illumination unit is a luminescence conversion LED, in which the phosphors are in direct or indirect contact with the chip.

14. The illumination unit as claimed in claim 1, wherein the illumination unit is an array of LEDs.

15. The illumination unit as claimed in claim 14, wherein at least one of the phosphors is applied to an optical device arranged in front of the LED array.