JP3232538B2 - Rare earth phosphor for monochrome CRT - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth phosphor used for a cathode ray tube (CRT), and more particularly to a rare earth phosphor used for a liquid crystal color shutter CRT.

[0002]

2. Description of the Related Art Recently, a liquid crystal color shutter CRT (Literature
quid Crystal Color Shutter CRT, hereafter referred to as LCS. ) Is attracting attention. this is,
Briefly, the B, G, and R components of the monochrome CRT are separated by a polarizer (polarizer) of a liquid crystal color shutter and a π cell disposed on the front of the monochrome CRT, and the components are superimposed and the brightness of the CRT is changed. Various colors are displayed by this.

[0003] In a shadow mask type CRT, one color is formed by three dots of G, B and R using three electron guns, but in the case of LCS, it is possible with one electron gun. Therefore, there is an advantage that the resolution is excellent. Also, while the shadow mask type is gray on the display surface,
The LCS has the advantage that the display surface is black and the contrast is very good because the liquid crystal color shutter is arranged on the front of the CRT.

On the other hand, since the LCS has poor transmittance of the liquid crystal color shutter, if it is desired to display the same brightness as that of a normal CRT, it is necessary to increase the brightness of the monochrome CRT on the rear surface, and burden the phosphor. However, there is a disadvantage in that

[0005] A phosphor used for an LCS monochrome CRT is required to emit approximately white light by a single substance, and it is particularly preferable to emit light of three colors, G, B and R. This is because if the phosphor is a mixed phosphor, color unevenness occurs due to a spot hit by the electron beam. It is also necessary to match the respective peak ratios of the phosphors to the polarizer used. As a phosphor that can satisfy the conditions to some extent, JEDEC P expressed by (Y, Tb) ₂ O ₂ S
Forty-five phosphors are known. In addition to this,
(Y, Tb, Sm) ₂ O ₂ disclosed in US Pat.
S phosphors can also be used.

FIG. 1 shows (Y _0.967 Tb _0.0025 Sm _0.0008 ) ₂
3 shows an emission spectrum of an O ₂ S phosphor. In the LCS, for example, a peak near 418 nm as a blue component, a peak near 545 nm as a yellow-green component, and a peak near 608 nm as an orange component of the phosphor are taken out, and these colors can be displayed by separating and synthesizing these. it can.

[0007]

As described above, as described above, LC
Since the brightness of the S display depends on the brightness of the monochrome CRT on the rear surface, that is, the brightness of the phosphor, the current density must be increased to excite the phosphor. However, conventional phosphors have poor current characteristics, so that improvement in luminance cannot be expected. In other words, even if the phosphor is excited by increasing the current density, the brightness does not increase beyond a certain level.
Monochrome CRTs have a problem in that luminance saturation occurs, and when excitation is continued at a high current density, a phenomenon called “burning” occurs in the phosphor, discoloring the phosphor and lowering the luminance. In fact, no improvement in brightness could be expected.

Accordingly, the present invention has been made in view of such circumstances, and an object of the present invention is to provide a rare earth phosphor with improved luminance saturation and burn.
This realizes a monochrome CRT with high luminance even when used in a high current density region for CS.

[0009]

Means for Solving the Problems The present inventors have conducted various experiments to improve the luminance saturation and burn of rare-earth phosphors. As a result, they have found that the inclusion of Lu can solve those problems. The present invention has been found. That is, the rare earth phosphor of the present invention has the general formula (Y
_1-XYZ , Lu _X , Tb _Y , Sm _Z ) A rare earth phosphor represented by ₂ O ₂ S, wherein X is in the range of 0 <X ≦ 0.05, and Y
Is in the range of 0.001 ≦ Y ≦ 0.005, and Z is 0 ≦ Z
≦ 0.05.

[0010] The phosphor of the present invention can be obtained by an ordinary method for producing a rare earth phosphor. For example, yttrium oxide,
After weighing rare earth oxide raw materials such as terbium oxide, lutetium oxide and samarium oxide so as to have a predetermined molar ratio, sulfur and a suitable flux (such as alkali metal or alkaline earth metal such as sodium carbonate and lithium fluoride) are used. (Halides, carbonates, etc.) by dry mixing and firing. Also, after dissolving the oxide in an acid, adding an oxalic acid solution to precipitate as an oxalate, firing the oxalate to form an oxide, and further adding sulfur, a flux, and firing,
It can also be obtained by firing in a hydrogen sulfide atmosphere.

[0011]

[Effect] FIG. 2 shows (Y _{1 -X} Lu _X Tb _0.0025 Sm _0.0008 )
FIG. 7 is a diagram showing the relationship between the current density and relative luminance of a prototype phosphor produced by changing the amount of lutetium (X value) of the ₂ O ₂ S phosphor;
Is 0.001, X is 0.005, C is 0.01,
D is the phosphor of the present invention with 0.03. This figure is
Not containing Lu (Y _0.9967 Tb _0.0025 Sm _0.0008 ) ₂ O ₂
A phosphor film is formed from an S phosphor, and the luminance when the phosphor film is excited at each current density at an acceleration voltage of 16 kV is 10%.
When 0% is set, the relative values of the film luminance of the phosphor of the present invention at each current density are plotted.

FIG. 3 shows that the phosphor shown in FIG.
FIG. 4 is a diagram showing the relationship between the current density of the phosphor and the relative luminance when excited by the acceleration voltage of A, B, C, and D are the same phosphor of the present invention as in FIG. (Y _0.9967 Tb _0.0025 Sm _0.0008 ) ₂ O ₂ S phosphor
This is the film brightness when excited at an acceleration voltage of 7 kV.

As shown in these figures, in the region of low current density, the luminance is reduced by containing Lu,
As the current density is increased, the luminance is improved.
The effect of having contained has appeared. It can be seen that the effect is particularly remarkable at an acceleration voltage of 27 kV and is overwhelmingly excellent.

FIG. 4 shows (Y _{1 -X} Lu _X Tb _0.0025 ) of the present invention.
It is a figure showing the relationship between the amount of lutetium and the powder brightness when the Sm _0.0008 ) ₂ O ₂ S phosphor is excited at an acceleration voltage of 7 kV and a current density of 0.5 μA. This figure also does not include Lu (Y
The powder luminance when the _0.9967 Tb _0.0025 Sm _0.0008 ) ₂ O ₂ S phosphor is excited under the same conditions is shown as 100%.

FIG. 5 shows (Y _{1 -Y} Lu _0.005 Tb _Y S
m _0.0008 ) is a diagram showing the relationship between the current density and the relative luminance of a phosphor prepared by changing the amount of terbium (Y value) of the ₂ O ₂ S phosphor. 0028,
G is 0.003 and H is 0.0035. This does not include Lu at an accelerating voltage of 16 kV as in FIG. 2 (Y _0.9967 Tb _0.0025 S
m _0.0008 ) When a phosphor film is formed of a ₂ O ₂ S phosphor and the luminance when the phosphor film is excited at each current density is set to 100%, the relative film luminance of the phosphor of the present invention at each current density is obtained. It is a plot of the values.

3 and 4, the luminance of the phosphor of the present invention tends to decrease as the amount of Lu increases, but by increasing the amount of Tb, the decrease in luminance of Lu is compensated for and the luminance is reduced. It can be seen that it can be improved.

From the above, the general formula is (Y _{1 -XYZ} , Lu _X , T
In the phosphor of the present invention represented by (b _Y , Sm _Z ) ₂ O ₂ S, the luminance saturation due to an increase in current density tends to be improved when the Lu amount, that is, the X value is larger than 0, but At the same time, the brightness tends to decrease, so that a practical value is preferably 0.05 or less. Further, the Tb amount, that is, the Y value is about 0.001 or more, and is approximately 418 nm and 545 shown in FIG.
A peak near nm is obtained, and the peak value at 545 nm increases and the peak value at 418 nm decreases as the amount increases. From the balance between the two peaks, a preferable range for maintaining white light emission is 0.001 ≦ Y ≦ 0.
005, more preferably 0.0015 ≦ Y ≦ 0.0035 in consideration of the improvement in luminance due to the addition of Tb as a phosphor for LCS.

In the phosphor of the present invention, white light can be emitted only from Tb without adding Sm.
In particular, when the Sm amount, that is, the Z value is in a range of 0.05 or less, preferably 0.005 or less, a peak near 608 nm shown in FIG.
It is particularly preferable as a phosphor for LCS, because it can emit light of three colors, G and R. However, when the value exceeds 0.05, the current characteristics are deteriorated and the brightness tends to decrease.

[0019]

【Example】

Examples 1 to 8 Yttrium oxide (Y ₂ O ₃ ), lutetium oxide (Lu ₂ O ₃ ), terbium oxide (Tb ₄ O ₇ ), samarium oxide (Sm ₂ O ₃ ) and sulfur (S ) And sodium carbonate (Na ₂ C) as a flux.
O ₃ ) was weighed out as shown in Table 1, and after they were thoroughly dry-mixed, filled in an alumina crucible and covered with a lid.
Baking was performed at 100 ° C. for 3 hours. After firing, the phosphor was washed several times to remove the flux, and then dried at 120 ° C. for 5 hours to obtain the phosphor of the present invention.

These phosphors were coated on a slide glass together with a binder, and the acceleration voltage was 27 kV and the current density was 10 μm.
When forcibly excited at A / cm ² for 30 minutes, all the coated surfaces were not discolored at all, the luminance was the same as before excitation, and no burning occurred. Also, the chromaticity points before excitation shown in Table 2 did not change at all.

[0021]

[Table 1] Below margin

[0022]

[Table 2]

[0023]

As described above, by adding Lu to the rare earth phosphor of the present invention, the current characteristics are remarkably improved, and luminance saturation and burn can be improved. Further, since the current characteristics are excellent, the chromaticity point of the phosphor does not change, and the phosphor is extremely excellent. Therefore, when this phosphor is used for an LCS monochrome CRT,
Even if the current density is increased, the luminance can be improved, and the luminance of the LCS display can be made equal to the luminance of a normal CRT display. The phosphor of the present invention is not only a phosphor for LCS but also a general monochrome CR.
It can also be used for T, and its utility value is very large.

[Brief description of the drawings]

FIG. 1 Lutetium-free (YTbSm) ₂ O ₂ S
FIG. 3 is a diagram showing one emission spectrum of a phosphor.

FIG. 2 is a diagram showing a relationship between current density and relative luminance of a phosphor according to one embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between current density and relative luminance of a phosphor according to one embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between lutetium content and relative luminance of a phosphor according to one embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between current density and relative luminance of a phosphor according to one embodiment of the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-52-130172 (JP, A) JP-A-53-11178 (JP, A) JP-A-64-22986 (JP, A) JP-A 52-13086 117290 (JP, A) JP-B 53-28146 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09K 11/84 CPD H01J 61/44 CA (STN)

Claims (2)

(57) [Claims] (1) When the general formula is (Y _1-XYZ , Lu _X , Tb
_Y, a rare-earth phosphor represented by _{Sm Z) 2 O 2 S,} X is in the range of 0 <X ≦ 0.05, Y is in the range of 0.001 ≦ Y ≦ 0.005, Items wherein Z is in the range of 0 ≦ Z ≦ 0.05
Rare earth phosphor for black CRT . 2. The compound represented by the general formula (Y _1-XYZ , Lu _X , Tb
_Y, a rare-earth phosphor represented by _{Sm Z) 2 O 2 S,} X is in the range of 0 <X ≦ 0.05, Y is in the range of 0.001 ≦ Y ≦ 0.005, Z is 0 <Ri range near the Z ≦ 0.05, around 418 nm, and pressurized to the emission peak near 545nm
The emission spectrum has an emission peak of Sm around 608 nm.
A rare earth phosphor for a monochrome CRT , comprising: