UV-emitting phosphor blend and tanning lamp containing same

1. A UV-emitting phosphor blend comprising a mixture of at least two UVA-emitting phosphors selected from SrB 4 O 7 :Eu, YPO 4 :Ce, and BaSi 2 O 5 :Pb, the mixture of UVA-emitting phosphors comprising 0 to 50 wt. % SrB 4 O 7 :Eu, 0 to 40 wt. % YPO 4 :Ce, and 30 to 70 wt. % BaSi 2 O 5 :Pb, the sum of the weight percentages of the phosphors in the mixture equaling 100%, the phosphor blend additionally containing an optional amount of a UVB-emitting phosphor having a range from 0 to 12 wt. % of the mixture.

2. The phosphor blend of claim 1 wherein the mixture of UVA-emitting phosphors comprises 30 to 40 wt. % SrB 4 O 7 :Eu, 30 to 40 wt. % YPO 4 :Ce, and 30 to 40 wt. % BaSi 2 O 5 :Pb.

3. The phosphor blend of claim 1 wherein the mixture of UVA-emitting phosphors comprises 30 to 35 wt. % SrB 4 O 7 :Eu, 30 to 35 wt. % YPO 4 :Ce, and 30 to 35 wt. % BaSi 2 O 5 :Pb.

4. The phosphor blend of claim 1 wherein the mixture of UVA-emitting phosphors comprises about 33.3 wt. % SrB 4 O 7 :Eu, about 33.3 wt. % YPO 4 :Ce, and about 33.3 wt. % BaSi 2 O 5 :Pb.

5. The phosphor blend of claim 1 wherein the mixture of UVA-emitting phosphors comprises 0 to 20 wt. % SrB 4 O 7 :Eu, 0 to 20 wt. % YPO 4 :Ce, and 50 to 70 wt. % BaSi 2 O 5 :Pb.

6. The phosphor blend of claim 1 wherein the mixture of UVA-emitting phosphors comprises 15 to 20 wt. % SrB 4 O 7 :Eu, 15 to 20 wt. % YPO 4 :Ce, and 65 to 70 wt. % BaSi 2 O 5 :Pb.

7. The phosphor blend of claim 1 wherein the mixture of UVA-emitting phosphors comprises about 16.7 wt. % SrB 4 O 7 :Eu, about 16.7 wt. % YPO 4 :Ce, and about 66.6 wt. % BaSi 2 O 5 :Pb.

8. The phosphor blend of claim 1 wherein the UVB-emitting phosphor is selected from Ce(Sr,Mg)Al 11 O 19 :Ce, Ce(Ca,Mg)A 11 O 19 :Ce, Ce(Ba,Mg)A 11 O 19 :Ce or LaPO 4 :Ce.

9. A UV-emitting phosphor blend comprising a mixture of 45 to 55 wt. % SrB 4 O 7 :Eu and 45 to 55 wt. % BaSi 2 O 5 :Pb wherein the sum of the weight percentages of the phosphors in the mixture equals 100%, the phosphor blend additionally containing an optional amount of a UVB-emitting phosphor having a range from 0 to 12 wt. % of the mixture.

10. The phosphor blend of claim 9 wherein the mixture of UVA-emitting phosphors comprises about 50 wt. % SrB 4 O 7 :Eu and about 50 wt. % BaSi 2 O 5 :Pb.

11. A UV-emitting phosphor blend comprising a mixture of 40 to 60 wt. % SrB 4 O 7 :Eu and 40 to 60 wt. % YPO 4 :Ce wherein the sum of the weight percentages of the phosphors in the mixture equals 100%, the phosphor blend additionally containing an optional amount of a UVB-emitting phosphor having a range from 0 to 12 wt. % of the mixture.

12. The phosphor blend of claim 11 wherein the mixture of UVA-emitting phosphors comprises 45 to 55 wt. % SrB 4 O 7 :Eu and 45 to 55 wt. % YPO 4 :Ce.

13. The phosphor blend of claim 11 wherein the mixture of UVA-emitting phosphors comprises about 50 wt. % SrB 4 O 7 :Eu and about 50 wt. % YPO 4 :Ce.

14. A fluorescent tanning lamp having a UV-transmissive envelope and a phosphor coating on an inner wall of the envelope, the phosphor coating containing a UV-emitting phosphor blend comprising a mixture of at least two UVA-emitting phosphors selected from SrB 4 O 7 :Eu, YPO 4 :Ce, and BaSi 2 O 5 :Pb, the phosphor blend additionally containing an optional amount of a UVB-emitting phosphor having a range from 0 to 12 wt. % of the mixture, wherein the lamp exhibits a 100 h UVA maintenance of at least about 87%.

15. The fluorescent lamp of claim 14 wherein the lamp exhibits a 0h UVA output of at least about 8800 μW/cm 2 .

16. The fluorescent lamp of claim 15 wherein the mixture of UVA-emitting phosphors comprises 0 to 50 wt. % SrB 4 O 7 :Eu, 0 to 40 wt. % YPO 4 :Ce, and 30 to 70 wt. % BaSi 2 O 5 :Pb.

17. The fluorescent lamp of claim 15 wherein the mixture of UVA-emitting phosphors comprises 0 to 20 wt. % SrB 4 O 7 :Eu, 0 to 20 wt. % YPO 4 :Ce, and 50 to 70 wt. % BaSi 2 O 5 :Pb.

18. The fluorescent lamp of claim 15 wherein the mixture of UVA-emitting phosphors comprises 40 to 60 wt. % SrB 4 O 7 :Eu and 40 to 60 wt. % BaSi 2 O 5 :Pb.

19. The fluorescent lamp of claim 15 wherein the envelope is tubular and further contains a reflector layer extending over a 220 20 segment of the circumference of the envelope, the reflector layer being disposed between the envelope and the phosphor layer, the phosphor layer extending over the entire circumference of the envelope.

20. The fluorescent lamp of claim 14 wherein the mixture of UVA-emitting phosphors comprises 40 to 60 wt. % SrB 4 O 7 :Eu and 40 to 60 wt. % YPO 4 :Ce.

21. The fluorescent lamp of claim 14 wherein the lamp exhibits a 100 h UVA maintenance of at least about 90%.

22. The fluorescent lamp of claim 14 wherein the UVB-emitting phosphor is selected from Ce(Sr,Mg)Al 11 O 19 :Ce, Ce(Ca,Mg)A 11 O 19 :Ce, Ce(Ba,Mg)A 11 O 19 :Ce or LaPO 4 :Ce.

23. A fluorescent tanning lamp having a UV-transmissive envelope and a phosphor coating on an inner wall of the envelope, wherein the lamp exhibits a normalized spectral power distribution defined by:

Wavelength

Normalized

Range

Intensity

(nm)

(%)

280–283

0.01–0.02

284–290

0.03–0.15

291–297

0.15–0.6 

298–306

0.5–1  

307–311

1–2

312–314

3–5

315–326

1–5

327–335

 6–17

336–340

18–20

341–352

20–35

353–360

36–66

361–366

 71–100

367–372

96–75

373–377

71–49

378–381

45–32

382–388

29–13

389–400

13–3.

24. The fluorescent lamp of claim 23 wherein the phosphor coating contains a UV-emitting phosphor blend comprising a mixture of at least two UVA-emitting phosphors selected from SrB 4 O 7 :Eu, YPO 4 :Ce, and BaSi 2 O 5 :Pb, and the phosphor blend additionally contains an optional amount of a UVB-emitting phosphor having a range from 0 to 12 wt. % of the mixture.

25. A UV-emitting phosphor blend comprising 62.3 wt. % BaSi 2 O 5 :Pb, 15.6 wt. % SrB 4 O 7 :Eu, 15.6 wt. % YPO 4 :Ce, and 6.5 wt. % SrCe 0.08 MgAl 11 O 18 .

26. A fluorescent tanning lamp having a UV-transmissive envelope and a phosphor coating on an inner wall of the envelope, the phosphor coating containing a UV-emitting phosphor blend comprising 62.3 wt. % BaSi 2 O 5 :Pb, 15.6 wt. % SrB 4 O 7 :Eu, 15.6 wt. % YPO 4 :Ce, and 6.5 wt. % SrCe 0.08 MgAl 11 O 18 .