Discharge lamp with high color temperature

1. A lamp comprising:

a discharge vessel;

electrodes extending into the discharge vessel; and

a discharge sustaining fill sealed within the discharge vessel, the fill comprising:

mercury;

an inert gas; and

a halide component comprising:

0.12-0.5 μmol/cm 3 of cesium halide,

a total of 0.1-1.6 μmol/cm 3 of at least one of indium halide and thallium halide,

a total of 0.3-1.5 μmol/cm 3 of at least one rare earth halide selected from dysprosium halide, holmium halide, neodymium halide and thulium halide, and

0.30-2.0 μmol/cm 3 of gadolinium halide;

a total of less than 0.2 μmol/cm 3 of halides other than cesium, gadolinium, thallium, indium, dysprosium, holmium, thulium, mercury, and neodymium, and

wherein in operation without a jacket at an arc wall loading of at least 2 watts/mm 2 , the lamp has a color temperature of from 7000K to 14,000K and a color rendering index (Ra) of at least 70.

2. The lamp of claim 1 , wherein the discharge vessel is free of a jacket.

3. A lamp comprising:

a discharge vessel;

electrodes extending into the discharge vessel; and

a discharge sustaining fill sealed within the discharge vessel, the fill comprising:

mercury;

an inert gas; and

a halide component comprising:

cesium halide,

at least one of indium halide and thallium halide, and

a rare earth halide component comprising at least one of dysprosium halide, holmium halide, neodymium halide and thulium halide, and

gadolinium halide;

wherein in operation without a jacket at an arc wall loading of at least 2 watts/mm 2 , the lamp has a color temperature of from 7000K so 14,000K and a color rendering index (Ra) of at least 70;

and wherein:

Gd

+

Y

P

ARC

⁢

Σ

>

R

 where Gd=the moles of gadolinium halide in the fill;

Y=In+Tl, where In=the moles of indium halide in the fill and Tl=the moles of thallium halide in the fill;

P ARC is the arc wall loading in W/mm 2 ;

Σ=the total moles of metal halide in the fill; and

R≧0.1 mm 2 /W.

4. The lamp of claim 3 , wherein: at least one of the following is satisfied,

(a) Gd≧2Y,In>Tl, and R=0.1;

(b) Gd≦1.8Y,In>Tl, and R=0.15; and

(c) Gd≦2Y,In>Tl, and R=0.15.

5. The lamp of claim 4 , wherein at least one of Gd=0 and Tl=0.

6. The lamp of claim 3 , wherein P ARC ≧3 W/mm 2 .

7. The lamp of claim 3 , wherein R≧0.13 mm 2 /W.

8. The lamp of claim 1 , wherein the rare earth halide includes neodymium.

9. The lamp of claim 1 , wherein the rare earth halide component includes at least one of dysprosium and neodymium.

10. The lamp of claim 9 , wherein the rare earth halide component includes gadolinium, dysprosium, and neodymium.

11. A lamp comprising:

a discharge vessel;

electrodes extending into the discharge vessel; and

a discharge sustaining fill sealed within the discharge vessel, the fill comprising:

mercury;

an inert gas; and

a halide component comprising:

cesium halide,

at least one of indium halide and thallium halide, and

a rare earth halide component comprising at least one of dysprosium halide, holmium halide, neodymium halide and thulium halide, and

optionally gadolinium halide; and

wherein the fill comprises less than 10 mole percent of halides other than halides of dysprosium, cesium, gadolinium, thallium, indium, and neodymium; and

wherein in operation without a jacket at an arc wall loading of at least 2 watts/mm 2 , the lamp has a color temperature of from 7000K to 14,000K and a color rendering index (Ra) of at least 70.

12. The lamp of claim 1 , wherein in operation, the color temperature is at least 7500K.

13. The lamp of claim 12 , wherein in operation, the color temperature is at least 9,000K.

14. The lamp of claim 13 , wherein the fill is substantially free of thallium.

15. The lamp of claim 11 wherein the fill comprises:

0.12-0.5 μmol/cm 3 of cesium halide;

0.30-2.0 μmol/cm 3 of gadolinium halide;

a total of 0.1-1.6 μmol/cm 3 of at least one of indium halide and thallium halide;

a total of 0.3-1.5 μmol/cm 3 of at least one rare earth halide selected from dysprosium, neodymium, holmium, and thulium; and

a total of less than 0.2 μmol/cm 3 of halides other than cesium, gadolinium, thallium, indium, dysprosium, holmium, thulium, mercury, and neodymium.

16. A lamp, comprising:

a discharge vessel;

electrodes extending into the discharge vessel; and

a discharge sustaining fill sealed within the discharge vessel, the fill comprising: mercury;

an inert gas; and

a halide component comprising:

cesium halide,

at least one of indium halide and thallium halide, and

a rare earth halide component comprising at least one of dysprosium halide, holmium halide, neodymium halide and thulium halide, and

wherein:

0.2

≤

Re

(

Gd

+

In

+

Tl

)

≤

2.0

wherein: Re=moles of rare earth halides in the fill selected from the group consisting of dysprosium, neodymium, holmium, and thulium halides, and combinations thereof;

Gd=moles of gadolinium halides in the fill,

In=moles of indium halides in the fill, and

Tl=moles of thallium halides in the fill,

wherein in operation without a jacket at an arc wall loading of at least 2 watts/mm 2 , the lamp has a color temperature of from 7000K to 14,000K and a color rendering index (Ra) of at least 70.

17. A lamp comprising:

a discharge vessel;

electrodes extending into the discharge vessel; and

a discharge sustaining fill sealed within the discharge vessel, the fill comprising:

mercury;

an inert gas; and

a halide component comprising:

cesium halide,

at least one of indium halide and thallium halide, and

a rare earth halide component comprising at least one of dysprosium halide, holmium halide, neodymium halide and thulium halide, and

optionally gadolinium halide; and

wherein the halide component in the fill satisfies following molar ratio:

0.38

≤

Cs

Re

≤

0.48

wherein Cs=moles of cesium halides in the fill; and

Re=moles of rare earth halides in the fill and;

wherein in operation without a jacket at an arc wall loading of at least 2 watts/mm 2 , the lamp has a color temperature of from 7000K to 14,000K and a color rendering index (Ra) of at least 70.

18. The lamp of claim 1 , wherein the fill comprises: 0.12-0.25 μmol/cm 3 of cesium halide; less than 0.3 μmol/cm 3 of gadolinium halide; a total of 0.8-4.5 μmol/cm 3 of at least one of indium and thallium halide; a total of 0.30-0.8 μmol/cm 3 of at least one rare earth halide selected from dysprosium, neodymium, holmium, and thulium halide; and a total of less than 0.2 μmol /cm 3 of halides other than cesium, gadolinium, thallium, indium, dysprosium, holmium, thulium, mercury and neodymium.

19. The lamp of claim 1 wherein the fill comprises less than 10 mole percent of halides other than halides of cesium, gadolinium, thallium, indium, dysprosium, holmium, thulium, mercury, and neodymium.

20. A method of operating the lamp of claim 1 , comprising:

supplying electrical power to the lamp to provide an arc wall loading of at least 2 watts/mm 2 , whereby the lamp has a color temperature of from 7000K to 14,000K and a color rendering index (Ra) of at least 70.