CS247082B2 - Luminescent material - Google Patents

Abstract

A fluorescent lamp has a phosphor film which is made of: a blue-emitting phosphor essentially consisting of at least one of a divalent europium activated aluminate phosphor having a general formula a(M, Eu)O &cirf& bAl2O3, and a divalent europium- and manganese-coactivated aluminate phosphor having a general formula a(M, Eu, Mn)O &cirf& bAl2O3, [where M is at least one of Zn, Mg, Ca, Sr, Ba, Li, Rb and Cs, and neither a nor b is zero]; a green-emitting phosphor essentially consisting of at least one of a cerium- and terbium-coactivated rare-earth silicophosphate phosphor having a general formula d(Lnl, Ce, Tb)2O3 &cirf& eSiO2 &cirf& fP2O5 [where LnI is at least one of Y, La, Gd, Lu and Sm, and none of d, e, and f is zero], and a rare-earth phosphate phosphor having a general formula (LnI, Ce, Tb)PO4 [where LnI is at least one of Y, La, Gd, Lu and Sm]; and a red-emitting phosphor essentially consisting of a europium- activated rare-earth oxide phosphor having a general formula (LnII, Eu)2O3 [where LnII is at least one of Y, La, Gd, Ce, Tb and Sm]. Tube-end blackening is greatly decreased by the phosphor combination in this fluorescent lamp.

Description

The invention relates to a luminifore consisting of a mixture of luminifors.

A three-cap emission system is known to be one of the methods to improve the color reproduction performance without sacrificing fluorescent efficiency. According to this system, three types of luminophores with peaks at about 450 nm, 540 nm and 610 nm are used. The half-widths of the light emission spectrum of these luminophores are relatively narrow. The blue emitting luminophore having a peak light emission spectrum at a wavelength of about 450 nm comprises a luminophore of a divalent europium-activated haloborophosphate, such as a luminophore of a divalent europium-activated strontium, magnesium, calcium, cerium boronophosphate.

A green-emitting luminophore having a peak emission spectrum at a wavelength of about 540 nm comprises a cerium and terbium-activated silicophosphate luminophore such as cerium and terbium-activated lanthanum silicophosphate, or a cerium and terbium-activated phosphate luminophore such as cerium and terbium activated lanthanum phosphate.

A red-emitting luminophore having a peak light emission spectrum at a wavelength of about 610 nm contains a luminophore

247082 .......

of europium-activated yttrium oxide.

Another three-cap emission system is described in Japanese Patent Application (Kokai) No. 57-128,778. This fluorescent lamp uses a combination of (Ba, Mg, Eu) O..bA22O3 as a blue emitting phosphor, MgO. B2O3: Ce, Tb as green-emitting luminophores and (Y, Eu) 2O3 as red-emitting luminophores.

The diameter of the lamp has recently been reduced to improve light efficiency at a lower cost. In general, when the diameter of the lamp is reduced, the load on the tube walls is increased. The end parts of the lamp are blackened, resulting in a so-called blackening effect. · When there is a blackening effect in a fluorescent lamp, the brightness of the lamp is reduced.

In a conventional 3-cap emission lamp having blue, green and red emitting luminophores, a blackening phenomenon occurs typically when a lamp having a diameter of 26 mm or less is used, resulting in poor appearance and poor brightness of the lamp.

The invention has been developed to overcome the disadvantages described above and aims to obtain a lamp with a high production value by substantially reducing the blackening at the end portions of the lamp.

Various types of attempts have been made to accomplish the above task and it has been found that the phenomenon of blackening was considerably. even when the diameter of the tube was 26 mm or less in a three-cap emission type fluorescent tube where at least one divalent europium-activated aluminate luminophore and a divalent manganese-activated aluminium luminophore were used instead of a conventional divalent europium-activated haloborophosphate luminophore in combination with the usual green and red-emitting luminophores. The invention is based on this discovery.

The phosphors used according to the invention are all known to those skilled in the art and are exposed to the blackening effect only when used separately. However, when these luminophores are used in combination, the blackening phenomenon decreases to an extent that could not be expected if used separately. The reduction of the blackening effect is based on the effect obtained by combining luminophores of different types.

The blue-emitting phosphor used according to the invention consists essentially of at least one phosphor of divalent europium-activated aluminate. and a divalent europium and manganese-co-activated aluminate luminophore, wherein the divalent europium activated aluminate luminophore has the general formula a (M, EujO. bA12O3, wherein M is at least one of zinc (Zn), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), lithium (Li), rubidium (Rb) and cesium (Cs) and neither and nor b is zero, and the divalent europium and manganese-aluminated aluminate phosphor has the general formula a (M, Eu, Where M, a, b have the same meaning as defined in the preceding formula This blue-emitting phosphor is described in Japanese Patent Nos. 56-152 882, 56-152 883 and 56-52 072. .

The green-emitting phosphor consists essentially of at least one cerium and terbium-co-activated rare earth silicophosphate and a cerium and terbium-coactivated rare earth phosphorous, wherein the cerium and terbium-co-activated rare earth siliconophosphate has the formula Ce (L). žO5. eSiO2. fP20s, wherein Lni is at least one of yttrium (Y), lanthanum (La), gadolinium (Gd), lutecia (Lu) and samaria (Sm), ad, e, f is not zero, and cerium and terbium coactivated phosphate luminophore Rare earth has the general formula ______________________ (Lni, Ce, Tb) PO4, where Lni has the same meaning as defined in the previous formula.

The red-emitting phosphor consists essentially of a europium-activated rare earth oxide having the general formula (LnII, Eu) 2O5, wherein LnII is at least one of yttrium (Y), lanthanum (La), gadolinium (Gd), cerium (Ce), terbia (Tb) and samaria (Sm).

An object of the present invention is. A luminophore characterized in that it consists of 0.1 to 40% by weight of a blue radiating luminophore consisting of at least one divalent europium-activated aluminate of the formula and (M, Eu) O. bA12O3, wherein M is at least one of zinc, magnesium, calcium, strontium, barium, lithium, rubidium and cesam and a> 0, b> 0, wherein 0.2? a / b> 1.5. and divalent europium and manganese co-activated aluminate of formula

Г '··;. ·,.' .. ^; Α * · '· ί ....

and (M, Eu, MnjO. bA12O3, wherein M, a and b are as defined above, 20 to 73% by weight of a green-radiating luminophore consisting of at least one cerium and a terbium-co-activated rare earth silicophosphate of formula (Lni, Ce, Tb) Wherein Lni is at least one of yttrium, lanthanum, gadolinium, lutecium and samarium and 0 < e + + f < 1.35 and cerium and terbium-co-activated rare earth phosphate of formula (Lni, Ce, Tb) PO4, wherein Ln1 is as defined above, and 5 to 65% by weight of a red-emitting luminophore consisting of a europium-activated rare earth oxide of the formula

·. wherein LnII is at least one of yttrium, lanthanum, gadolinium, cerium, terbium and samarium, wherein the total weight of the individual phosphors is 100% by weight;

A particularly preferred combination of phosphors is composed of:

blue-emitting luminophore of formula a (M, Eu, Mn) O. bA12O3,

4 7 3 8 3

With green-emitting phosphor of formula (Lni, CeTb) 2O3. eSiO2. fP2O, and a red-emitting luminophore of formula (LnII, Eu] 2O3, /

By this combination, the blackening effect is minimized and a bright fluorescent lamp is obtained.

The luminophore fluorescent lamp of the present invention reduces blackening in the end portions of a three-cap emission type fluorescent lamp.

The invention will now be described with reference to the accompanying drawing, which illustrates graphically the light emission spectrum in the initial state of switching on a fluorescent lamp according to one embodiment of the invention.

The blackening of the tubular ends represents the so-called blackening phenomenon in the end portions of the lamp while being connected, thereby degrading the outer appearance of the lamp and thereby reducing its value.

The ends of the tube are blackened when the discharge gas is activated in the tube. The blackening of the ends of the tube varies according to the material emitted from the phosphors and cathode or the type of gas sealed in the tube. However, blackened parts always occur in the vicinity of the electrodes.

To evaluate the end blackening of the tube, the predetermined blackened portion is cut to include the tube glass and the luminophore screen, and the visible light transmittance of the blackened portion is measured. As blackness increases, the visible light transmittance is reduced.

The blackened portion of the 40 W fluorescent tube with a 25 mm tube diameter having a luminophore as described above is subjected to visible light transmittance measurement. The visible light transmittance of the fluorescent lamp of the present invention is compared to that of a bivalent fluorescent having a barium europium-activated haloborophosphate strontium, calcium, magnesium and tsar luminophore.

In this case, when the visible light transmittance of the fluorescent lamp is given as 100%, the visible light transmittance of the comparative fluorescent lamp of the invention is 115 ° / o. The degree of blackening of the lamp according to the invention is reduced by 15%. The measurement of the blackening of the tube ends must be made after a relatively long period of operation of the lamp. The 40 W fluorescent lamp of the invention and a conventional fluorescent lamp were connected for 1500 hours at 130% load.

Blackened parts, ie the part between the position 30 mm from the end of the lamp and the position 45 mm. from the same end of the lamp in the longitudinal direction of the lamp having a length of 15 millimeters and a width of 15 mm respectively are cut off from the lamps. These blackened 15 x 15 mm sections are given as samples. The visible light transmittances of these samples were measured with a Beckmann transmittance meter.

When using a 3-cap emission lamp as a high color reproduction lamp in practice, the average color reproduction index (Ra) is 30 or more and the lamp performance is 80 Im / W or more.

Alkali metal, boron oxide, gallium oxide or the like can be added in small portions to the individual blue, green, and red emitting phosphors. Luminophores with such additives can be used to obtain the same effect as in the above embodiment.

The invention will now be described in detail by way of example.

Example 1

Luminescent of divalent europium-activated aluminium-magnesium magnesium alumina

3 (Ba, Mg, Eu). 8 Al2O3 is used as a blue-emitting luminophore. This phosphor is referred to below as phosphor (A). The luminophore (A) has a narrow light emission spectrum with a peak at a wavelength of 452 nm and is suitable as a blue emitting luminophore of the three-peak emission type.

For a comparative fluorescent lamp, a divalent europium-activated strontium, magnesium and cerium haloborophosphate luminophore of the formula

3 (Sr, Mg, E11, Ce) O.0.92 P2O5.0.31 CaCl2.

. 0.09 B2O3 as a blue-emitting luminophore. This phosphor is referred to below as phosphor (B).

wt. % luminophore (A) as a blue radiating luminophore, 67 wt. % cerium and terbium-coactivated lanthanum silicophosphate of formula (La, Ce, Tb) 2O3.0.2 S1O2.0.9 P2O5 as a green-emitting luminophore, and 22 wt. % luminophore from europium-activated yttrium oxide as the red-emitting luminophore was used to prepare a 40 W 5,000-K fluorescent tube having a tube diameter of 25 min according to Example 1 by the conventional method. This lamp was connected for 1500 hours and was then subjected to visible light transmittance measurements.

On the other hand, the luminophores (B) were used as the blue emitting luminophore, the cerium luminophore and the terbium-coactivated lanthanum silicophosphate as the green emitting luminophore and the europium-activated yttrium luminophore as the red emitting luminophore. 25 mm.

The light emission distribution of the fluorescent lamp of Example 1 is shown in the drawing during the initial power-on period. The visible light transmittance of the reference lamp was 100% and the fluorescent lamp of Example 1 was 115%, thus reducing the blackening effect by 15%.

Furthermore, the above-mentioned phosphors were used individually to prepare similar fluorescent lamps, and these lamps were switched on for 1500 hours. Visible light transmittance for the following lamps, including:

the phosphorous (A), the phosphorous (B), the phosphorous (La, Ce, Tb) 2O3.0.2 SiO2.0.9 P2O5, and the phosphorous (Y, Eu) 2C3, respectively, were 92%, 90%, 104% and 101 percent.

Further, as another comparative example, the same blue and red-emitting luminophores as in Example 1 were used to prepare a fluorescent lamp together with MgO. B2O3: Ce, Tb as a green-emitting luminophore. This lamp was connected for 1,500 hours and its visible light transmittance was measured at 99%,

Theoretically, the visible light transmittance of a three-cap emission type fluorescent lamp is expected to be 102% as the best of the visible light transmittance of the individual luminophores and luminophores measured. In practice, however, the visible light transmittance of Example 1 is obtained at 115%. This is due to the combined effect of the luminophores.

The average color reproduction index (Ra) in the initial start-up period is 84, and the lamp power is 90 lm / W.

The above results are summarized in the following table.

Examples 2 to 7

The luminophor combination was varied within their contents according to the invention, the lamps in Examples 2 to 7 were prepared according to the same method as in Example 1.

In fluorescent lamps, a luminophore was used as a comparative example

3 (Sr, Mg, Eu, Ce) .0.92 P2O5.0.31 CaCl2. . 0.09 B2O3 as a blue-emitting luminophore. The other conditions were the same as in the respective examples. Visible light transmittances, average color reproduction indexes and fluorescent lamp performance of Examples 2 to 7 are shown in the table. It should be noted that the visible transmittance is given with respect to the 100% visible transmittance of the comparative examples.

Table

example composition of luminophores content pass- average performance wt. ·% company index fluorescent lamps visible light color reproduction · (Ra) (lm / W) (%) 2 3 4 5 6 1 3 (Ba, Mg, Eu). 8 Al2O3 (La, Ce, Tb) 2O3.0.2 SiO2. 11 . 0.9 P2O5 67 115 84. 90 (Y, Eu) 2 O 3 22nd 2 3 (Ba, Mg, Eu, MnJO.8 Al2O3 10 (La, Ce, Tb, Gd). 66 110 86 87 . 0.85 P2O5 (Y, Eu, Tb) 2O3 24 3 2.8 (Ba, Mg, Zn, Eu, Mn) 0. 10 . 8 AI2O3 70 104 86 84 (La, Ce, Tb) PO 4 (Y, Eu, Sm) 2 O 3 20 May 4 2.8 (Ba, Mg, Eu) O. 0.798 AI2O3. 14 . 0.02 B2O3 65 113 84 89 (La, Ce, Tb, Lu) 2O5.0.2 SiO2. 21

. 0.9 P2O5 (Y, Eu) 2O3

247082 9 10 example composition of luminophore content pass- average performance wt. % company index fluorescent lamps visible light color reproduction (Ra) (lm / Wj (%) 1 2 3 4 5 6 5 3 (Ba, Mg, Ca, Li, EujO. 8 Al 2 O 3 (La, Ce, Tb, Υ) 2θ3.0,24 SiO 2. 16 . 0.88 P2O5 60 113 85 83 (Y, Eu, Laj2O3 24 6 3 (Ba, Mg, Zn, Rb, Eu, MnO0.8 Al2O3 (La, Ce, Tb, Sm) 2O3.0.26 S1O2. 20 May . 0.87 P2O5 54 112 86 85 (Y, Eu, Ce) 2 O 3 26 7 3 (Ba, Mg, Sr, Cs, EujO.8 Al2O3 23 (La, Ce, TbjPOd 54 106 84 87 (Y, Eu, Gd 2 O 3 23

OBJECT OF INVENTION

Claims (1)

OBJECT OF INVENTION Luminophore characterized in that it consists of 0.1 to 40% by weight of a blue-emitting luminophore consisting of at least one divalent europium-activated aluminate of the formula and (M, EujO. BA12O3, where M is at least one of zinc) , magnesium, calcium, strontium, barium, lithium, rubidium and cesium aa> 0, b> 0, with 0.2 <a / b> 1.5, and divalent europium and manganese-co-activated aluminate of formula a (M, Eu, MnjO, bA12O3, wherein M, a and b are as hereinbefore defined, 20 to 73% by weight of a green-radiating luminophore consisting of at least one cerium and terbium-co-activated rare earth silicophosphate of general formula (Lni, Ce, Tb). Lni is at least one of yttrium, lanthanum, gadolinium, lutecium and samarium and Rare soils of formula (Lni, Ce, TbJPOa, where Lni is as defined above) and 5 to 65% by weight of a red-emitting phosphor consisting of a europium-activated rare earth oxide of the formula (LnII, Euj2O3, wherein LnII is at least one of yttrium, lanthanum, gadolinium, cerium, terbium and samarium, wherein the total weight of the individual phosphors is 100% by weight.