Low-pressure discharge lamp with fluorescent particles having a small particle size
In different embodiments, a low-pressure discharge lamp ( 1 ) is provided. The low-pressure discharge lamp has a discharge vessel ( 2 ) and a coating structure ( 7 ). The coating structure is formed on an inner face of the discharge vessel ( 2 ). The coating structure ( 7 ) has first fluorescent particles ( 34 ) which have at least one fluorescent substance that emits red light and the average particle size of which ranges from 0.5 μm to 1.9 μm, second fluorescent particles ( 36 ) which have at least one fluorescent substance that emits green light and the average particle size of which ranges from 0.6 μm to 2.8 μm or from 1 μm to 4 μm, and third fluorescent particles ( 38 ) which have at least one fluorescent substance that emits blue light and the average particle size of which ranges from 1 μm to 4 μm.
1. Low-pressure discharge lamp, with a discharge vessel and a coating structure formed on an inside of the discharge vessel, the coating structure comprising:
first fluorescent particles which have a least one fluorescent substance emitting red light and the mean particle size of which lies in a range from 0.5 μm to 1.9 μm,
second fluorescent particles which have at least one fluorescent substance emitting green light and the mean particle size of which lies in a range from 0.6 μm to 2.8 μm or from 1 μm to 4 μm, and
third fluorescent particles which have at least one fluorescent substance emitting blue light and the mean particle size of which lies in a range from 1 μm to 4 μm;
wherein the fluorescent substances each comprise activators and host lattices doped with the activators, wherein
a proportion of the activators in the fluorescent substance emitting green light lies in the range from 6.5 mol % to 16 mol % or from 20 mol % to 50 mol %,
a proportion of the activators in the fluorescent substance emitting red light lies in the range from 2.3 mol % to 5.5 mol %, and/or
a proportion of the activators in the fluorescent substance emitting blue light lies in the range from 3.0 mol % to 11.0 mol %.
2. Low-pressure discharge lamp according to claim 1 , wherein
the mean particle size of the first fluorescent particles lies in a range from 1.2 μm to 1.7 μm, and/or
the mean particle size of the second fluorescent particles lies in a range from 1 μm to 2.5 μm or from 1.5 μm to 3.5 μm, and/or
the mean particle size of the third fluorescent particles lies in a range from 1.5 μm to 3.5 μm.
3. Low-pressure discharge lamp according to claim 2 , wherein
the mean particle size of the second fluorescent particles lies in a range from 1.7 μm to 2.3 μm or from 2.0 μm to 3.4 μm, and/or
the mean particle size of the third fluorescent particles lies in a range from 2.5 μm to 3.3 μm.
4. Low-pressure discharge lamp according to claim 1 , wherein
a quantity of activators per 120 cm lamp length in the fluorescent substance emitting red light and the fluorescent substance emitting blue light lies in a range from 4.17*10 −5 mol to 3.84*10 −4 mol, and/or
a quantity of activators per 120 cm lamp length in the fluorescent substance emitting green light lies in a range from 5.06*10 −5 mol to 4.60*10 −4 mol.
5. Low-pressure discharge lamp according to claim 1 , wherein the activators comprise rare earth metals.
6. Low-pressure discharge lamp according to claim 5 , wherein the activators comprise europium and/or terbium.
7. Low-pressure discharge lamp according to claim 1 , wherein the coating structure comprises
a protective coating formed on an inside of the discharge vessel, and
a fluorescent coating formed on the protective coating and comprising the fluorescent particles.
8. Low-pressure discharge lamp according to claim 7 , wherein the protective coating comprises aluminium oxide and/or pyrogenic and/or highly dispersed aluminium oxide.
9. Low-pressure discharge lamp according to claim 1 which in operation emits white light.
10. Low-pressure discharge lamp according to claim 1 which in operation has discharge currents in the range from 140 mA to 800 mA.
11. Low-pressure discharge lamp according to claim 1 wherein the light yield lies in a range from 70 lm/W to 120 lm/W.
12. Low-pressure discharge lamp according to claim 1 wherein a colour temperature of the generated light lies in the range from 2,500 K to 6,500 K.
13. Low-pressure discharge lamp according to claim 1 wherein the quantum efficiency of the fluorescent substances lies in a range from 80% to 100%.