Illumination unit having at least one LED as light source

• US 6,670,748 B2
• Filed: 07/26/2002
• Issued: 12/30/2003
• Est. Priority Date: 09/25/2001
• Status: Expired due to Term

• Current Assignee: OSRAM OLED GMBH (Ams-Osram AG)
• Original Assignee: Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen mbH (Ams-Osram AG)
• Inventors: Fiedler, Tim, Huber, Günter, Ellens, Andries, Fries, Torsten
• Primary Examiner(s): Patel, Ashok
• Assistant Examiner(s): HARPER, HOLLY R
• Application Number:
  US10/205,922
• Publication Number:
  US 20030094893A1
• Time in Patent Office: 522 Days
• Field of Search: 252/301.4 F, 313/503, 313/502, 313/483, 313/485, 313/512, 257/88, 257/98
• 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 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• 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 2235/766 Trigonal symmetry, e.g. alpha-Si3N4 or alpha-Sialon
• CPC Class Codes: C04B 2235/9646 Optical properties
• CPC Class Codes: C04B 35/597 based on silicon oxynitride, e.g. SIALONS
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77218 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/77347 Silicon Nitrides or Silicon Oxynitrides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/77747 Silicon Nitrides or Silicon Oxynitrides
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• 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 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
• CPC Class Codes: H01L 33/502 : Wavelength conversion materials
• CPC Class Codes: Y02B 20/00 : Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

An illumination unit having at least one LED as light source, the LED emitting primary radiation in the range from 300 to 570 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 nitride-containing phosphor which emits with a peak emission wavelength at 430 to 670 nm and which originates from the class of the Ce- or Eu-activated nitrides, oxynitrides or sialons.

Claims

1. An illumination unit having at least one LED as light source, the LED emitting primary radiation in the range from 300 to 570 nm, this radiation being partially or completely converted into the longer-wave radiation by phosphors which are exposed to the primary radiation of the LED and the structure of which is based on nitrides or derivatives thereof, wherein the conversion takes place with the aid of at least one phosphor which is derived from a cation M and a silicon nitride or a derivative of a nitride which emits with a peak emission wavelength at 430 to 670 nm, the cation being partially replaced by a dopant D, namely Eu²⁺ or Ce³⁺, at least one of the divalent metals Ba, Ca, Sr and/or at least one of the trivalent metals Lu, La, Gd, Y being used as cation M, the phosphor originating from one of the following classes:

nitrides of the structure MSi₃N₅, M₂Si₄N₇, M₄Si₆N₁₁ and M₉Si₁₁N₂₃,

oxynitrides of the structure M₁₆Si₁₅O₆N₃₂

sialons of the structure MSiAl₂O₃N₂, M₁₃Si₁₈Al₁₂O₁₈N₃₆, MSi₅Al₂ON₉ and M₃Si₅AlON₁₀.

2. The illumination unit as claimed in claim 1, wherein the proportion of the dopant is 0.5 to 15 mol % of the cation.

3. The illumination unit as claimed in claim 1, wherein, in the case of doping with Ce³⁺, an additional dopant, namely Pr³⁺ and/or Tb³⁺, is used, the content of which forms at most 30 mol % of the Ce³⁺ content.

4. The illumination unit as claimed in claim 1, wherein, in the case of doping with Eu²⁺, an additional dopant, namely Mn²⁺, is used, the proportion of which additional dopant amounts to at most four times the proportion of Eu²⁺.

5. The illumination unit as claimed in claim 1, wherein each Eu²⁺ ion in the phosphor is coordinated by at least two or more nitride ligands.

6. The illumination unit as claimed in claim 1, wherein a plurality of nitride-containing phosphors are used together, and in particular exclusively, in order to produce in particular a white-emitting illumination unit.

7. The illumination unit as claimed in claim 1, wherein the phosphors according to the invention are dispersed in silicone resin or are applied directly to the LED.

8. The illumination unit as claimed in claim 1, wherein the LED is a nitride-based semiconductor component.

9. The illumination unit as claimed in claim 6, wherein, to generate white light, the primary radiation emitted is in the wavelength region from 360 to 420 nm, the primary radiation emitted being exposed to at least three phosphors with an emission maximum in the blue (430 to 470 nm), green (495 to 540 nm) and red (in particular 540 to 620 nm) for conversion.

10. The illumination unit as claimed in claim 6, wherein, to generate white light, the primary radiation emitted is in the wavelength region from 420 to 480 nm, the primary radiation emitted being exposed to at least two phosphors with an emission maximum in the green (495 to 540 nm) and red (in particular 540 to 620 nm) for conversion.

11. The illumination unit as claimed in claim 1, wherein, to generate colored light, the primary radiation emitted lies in the UV wavelength region from 300 to 570 nm, the primary radiation emitted being exposed to a single phosphor as described in claim 1.

12. The illumination unit as claimed in claim 1, wherein the nitride-containing phosphor is M′

M″

Si₄N₇;

D,

where M′

=Sr or Ba, in each case alone or in combination, (in particular M′

is replaced by up to 20 mol % of Ca);

M″

=Lu alone or in combination with Gd and/or La.

13. The illumination unit as claimed in claim 1, wherein the nitride-containing phosphor is M′

M″

Si₆N₁₁;

D, where M′

=Ba_xSr<sub>3−

x</sub>, with 1.3≦

x≦

1.7;

in particular with a small amount of added Ca;

M″

=Lu alone or in combination with Gd and/or La and/or Y.

14. The illumination unit as claimed in claim 1, wherein the nitride-containing phosphor is M′

₂M″

₇Si₁₁N₂₃;

D, where M′

=Ba alone or in combination with Sr (up to 50 mol %) and M″

=La alone or in combination with Gd and/or Lu.

15. The illumination unit as claimed in claim 1, wherein the nitride-containing phosphor is M″

Si₃N₅;

D, where M″

=La alone or in combination with Gd and/or Lu, and where D=Ce.

16. The illumination unit as claimed in claim 1, wherein the nitride-containing phosphor is M″

₁₆Si₁₅O₆N₃₂;

Ce, where M″

=La alone or in combination with Gd and/or Lu.

17. The illumination unit as claimed in claim 1, wherein the nitride-containing phosphor is M′

SiAl₂O₃N₂;

D, where M′

=Sr alone or in combination with Ba and/or Ca;

in particular, the proportion of Ba may be up to 50 mol %, and the proportion of Ca may be up to 20 mol %.

18. The illumination unit as claimed in claim 1, wherein the nitride-containing phosphor is M′

₃M″

₁₀Si₁₈Al₁₂O₁₈N₃₆;

D, where M′

=Sr alone or in combination with Ba and/or Ca;

in particular, the proportion of Ba may be up to 50 mol %, and the proportion of Ca may be up to 20 mol %;

where M″

=La alone or in combination with Gd and/or Lu.

19. The illumination unit as claimed in claim 1, wherein the nitride-containing phosphor is M″

Si₅Al₂ON₉;

Ce³⁺, where M″

=La alone or in combination with Gd and/or Lu.

20. The illumination unit as claimed in claim 1, wherein the nitride-containing phosphor is M″

₃Si₅AlON₁₀;

Ce³⁺, where M″

=La alone or in combination with Gd and/or Lu.

21. 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.

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

23. The illumination unit as claimed in claim 12, wherein at least one of the phosphors is applied to an optical device arranged in front of the LED array.

24. A pigment with daylight fluorescence, in particular a phosphor, the structure of which is based on nitrides or derivatives thereof, wherein the composition is derived from a cation M and a silicon nitride or a derivative of a nitride, the cation being partially replaced by a dopant D, namely Eu²⁺ or Ce³⁺, the cation M used being at least one of the divalent metals Ba, Ca, Sr and/or at least one of the trivalent metals Lu, La, Gd, Y, the phosphor originating from one of the following classes:

nitrides of the structure MSi₃N₅, M₂Si₄N₇, M₄Si₆N₁₁ and M₉Si₁₁N₂₃,

oxynitrides of the structure M₁₆Si₁₅O₆N₃₂

sialons of the structure MSiAl₂O₃N₂, M₁₃Si₁₈Al₁₂O₁₈N₃₆, MSi₅Al₂ON₉ and M₃Si₅AlON₁₀.

25. The pigment as claimed in claim 24, wherein the proportion of the dopant is 0.5 to 15 mol % of the cation.

26. The pigment as claimed in claim 24, wherein, in the case of doping with Ce³⁺, an additional dopant, namely Pr³⁺ and/or Tb³⁺, is used, the content of which forms at most 30 mol % of the Ce³⁺ content.

27. The pigment as claimed in claim 24, wherein, in the case of doping with Eu²⁺, an additional dopant, namely Mn²⁺, is used, the proportion of which additional dopant amounts to at most four times the proportion of EU²⁺.

28. The pigment as claimed in claim 24, wherein each Eu²⁺ ion in the phosphor is coordinated by at least two or more nitride ligands.

29. The pigment as claimed in claim 24, wherein the nitride-containing phosphor is M′

M″

Si₄N₇;

D, where M′

=Sr or Ba, in each case alone or in combination, (in particular M′

is replaced by up to 20 mol % of Ca);

M″

=Lu alone or in combination with Gd and/or La.

30. The pigment as claimed in claim 24, wherein the nitride-containing phosphor is M′

M″

Si₆N₁₁;

D, where M′

=Ba_xSr<sub>3−

x</sub>, with 1.3≦

x≦

1.7;

in particular with a small amount of added Ca;

M″

=Lu alone or in combination with Gd and/or La and/or Y.

31. The pigment as claimed in claim 24, wherein the nitride-containing phosphor is M′

₂M″

₇Si₁₁N₂₃;

D, where M′

=Ba alone or in combination with Sr (up to 50 mol %) and M″

=La alone or in combination with Gd and/or Lu.

32. The pigment as claimed in claim 24, wherein the nitride-containing phosphor is M″

Si₃N₅;

D, where M″

=La alone or in combination with Gd and/or Lu, and where D=Ce.

33. The pigment as claimed in claim 24, wherein the nitride-containing phosphor is M″

₁₆Si₁₅O₆N₃₂;

Ce, where M″

=La alone or in combination with Gd and/or Lu.

34. The pigment as claimed in claim 24, wherein the nitride-containing phosphor is M′

SiAl₂O₃N₂;

D, where M′

=Sr alone or in combination with Ba and/or Ca;

in particular, the proportion of Ba may be up to 50 mol %, and the proportion of Ca may be up to 20 mol %.

35. The pigment as claimed in claim 24, wherein the nitride-containing phosphor is M′

₃M″

₁₀Si₁₈Al₁₂O₁₈N₃₆;

D, where M′

=Sr alone or in combination with Ba and/or Ca;

in particular, the proportion of Ba may be up to 50 mol %, and the proportion of Ca may be up to 20 mol %;

where M″

=La alone or in combination with Gd and/or Lu.

36. The pigment as claimed in claim 24, wherein the nitride-containing phosphor is M″

Si₅Al₂ON₉;

Ce³⁺, where M″

=La alone or in combination with Gd and/or Lu.

37. The pigment as claimed in claim 24, wherein the nitride-containing phosphor is M″

₃Si₅AlON₁₀;

Ce³⁺, where M″

=La alone or in combination with Gd and/or Lu.