JP2003055658A - Monochromatic phosphor for fed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monochromatic phosphor for a field emission display(FED) which exhibits a wide color reproduction range and a very small color shift. SOLUTION: This monochromatic phosphor has a composition represented by the formula: (Y1-p-q-r-s-t , Tbp , Ceq , Eur , Sms , Prt )2 Sia O3+2a (wherein 0.001<=p<=0.20, 0.0005<=q<=0.05, 0<=r<=0.20, 0<=s<=0.15, 0<=t<=0.05, and 0.5<=a<=1.0).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monochrome phosphor used in a field emission display (referred to as FED in this specification).

[0002]

2. Description of the Related Art An FED is a flat panel display having a cathode and an anode facing the cathode and having a structure in which a fluorescent film provided on the anode side is excited by an electron beam to emit light. The acceleration voltage of the electron beam that excites the anode is about 0.1 to 10 kV. This acceleration voltage is
In comparison with the accelerating voltage of the CRT, which is several tens of kV, the accelerating voltage is low in all cases. From the above, a dedicated phosphor that is excited by a slow electron beam is used for the FED.

Since the FED has a lower accelerating voltage of the electron beam for exciting the phosphor than the television, the energy for exciting the phosphor is small. A small excitation energy cannot cause the phosphor to emit light with high brightness. Therefore, the FED emits light with high brightness by increasing the current density for exciting the phosphor as compared with the television. The use of phosphors for televisions at high current densities significantly shortens their lifetime. For this reason, phosphors of various emission colors are used as phosphors for televisions, but most of them cannot be used for FEDs.

A ZnO: Zn phosphor has been developed as a monochrome phosphor for an FED that can be used at a high current density. The emission color of this phosphor is Green. The optimal emission color for a monochrome phosphor is white. For phosphors that cannot emit white light, the emission color is changed using a filter. However, changing the emission color using a filter complicates the entire structure. In addition, there is also a drawback that the color of emitted light changes due to deterioration of the filter. Further, since the filter absorbs a part of the spectrum emitted from the phosphor and changes the emission color, the emission color of the spectrum not emitted from the phosphor cannot be obtained. Therefore, ZnO:
The Zn phosphor has a limited reproducible color tone and is not ideal as a monochrome phosphor.

This drawback can be eliminated by mixing phosphors that emit green light, blue light and red light, for example. The color-mixed phosphor uses Y ₂ SiO ₅ : Tb as a green light emitting phosphor, Y ₂ SiO ₅ : Ce as a blue light emitting phosphor, and Y ₂ O ₃ : Eu as a red light emitting phosphor. it can.

[0006]

This mixed phosphor can be adjusted to a desired color tone by the mixing ratio of the three color phosphors to be mixed. However, phosphors in which a plurality of phosphors are mixed have different life characteristics due to different phosphor compositions, and there is a drawback in that color shift occurs when the usage time becomes long. In particular, since the life characteristics of the Red phosphor are better than those of the other colors, there arises a problem that the emission chromaticity causes a color shift in the red direction with use.

The present invention was developed with the object of solving this drawback. An important object of the present invention is to provide a monochrome phosphor for an FED, which can widen a color reproduction range and can extremely reduce color misregistration.

[0008]

The monochrome phosphor for FED of the present invention has the following general composition formula. (Y _1-p-q-r-s-t , Tb _p , Ce _q , E
u _{r, Sm s,} in _{Pr t) 2 Si a O 3} + 2a this formula, Tb is related to green-emitting, green-emitting color is increased and this increases. Q indicating the amount of Tb
Is preferably 0.001 ≦ p ≦ 0.20, more preferably 0.01 ≦ p ≦ 0.04. When p is less than 0.001, the light emitting property of the phosphor deteriorates. On the other hand, when p is more than 0.20, concentration quenching occurs and the brightness deteriorates. Ce is related to the emission of blue light, and when it increases, the emission color blue increases. The q indicating the Ce amount is preferably 0.0005 ≦ q ≦ 0.05. This value is more preferably 0.001 ≦ q ≦ 0.02. q is 0.0
When it is less than 005, the light emission characteristics are deteriorated, and when it is more than 0.05, concentration quenching occurs and the brightness is deteriorated. Eu is related to the emission of red light, and when it increases, the emission color red increases. R, which represents the amount of Eu, is preferably 0 ≦ r ≦ 0.20. More preferably, 0 ≦ r ≦ 0.02. If this value is more than 0.20, density quenching occurs and the brightness deteriorates. Sm is related to the emission of red light, and when it increases, the emission color red increases. S indicating the Sm amount is preferably 0
≦ s ≦ 0.15. More preferably 0 ≦ s ≦ 0.0
Set to 2. If this value is more than 0.15, density quenching occurs and the brightness deteriorates. Pr is related to the emission of yellow light, and when it increases, the emission color yellow increases. T indicating the Pr amount
Is preferably 0 ≦ t ≦ 0.05. More preferably, 0 ≦ t ≦ 0.02. If the value of t is more than 0.05, density quenching occurs and the brightness deteriorates. When Si is the main additive, Si increases the emission color blue when a increases. A indicating the amount of Si is preferably 0.5 ≦ a
≦ 1.0. If this value is less than 0.5, the luminance characteristics deteriorate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. However, the examples described below exemplify a monochrome phosphor for an FED for embodying the technical idea of the present invention, and the present invention does not specify the monochrome phosphor as the following.

[0010]

[Example] [Example 1] The following raw materials are prepared.・ Coprecipitated oxide with the following composition: 100g ・ Small silica (SiO ₂ ): 25.9g

It is a coprecipitated oxide (Y _0.950 , Tb
_0.02 , Ce _0.010 , Eu _{0. 02} ) ₂ O ₃ is manufactured by the following steps. (1) Y ₂ O ₃ 107.3 g and Tb ₄ O ₇ 3.7 g
And 1.7 g of CeO ₂ and 3.5 g of Eu ₂ O ₃ in HNO
₃ Dissolve in aqueous solution. (2) While stirring the solution of (1), add an aqueous solution in which 500 g of oxalic acid is dissolved. The resulting precipitate is nutsched, washed with water and separated. (3) Put the oxalate made in (2) into a quartz crucible,
Cover and bake at 900 ° C. for 15 hours. After cooling, it is taken out from the crucible to obtain a coprecipitated oxide.

Coprecipitated oxide and fine silica (SiO ₂ )
Put 200 ml of ethanol and 200 g of aluminum balls together in a magnetic pot and mill for 2 hours. Transfer the raw material removed from the magnetic pot to a vat, and
Heat to 05 ° C. to dry. In this step, 125 g of mixed raw material is obtained. The mixed raw material is placed in an alumina crucible. Cover the crucible and bake at 1500 ° C. for 3 hours. After being placed in a crucible and cooled, the baked product taken out from the crucible, 200 g of beads, and 400 ml of water are put into a plastic bottle, and the baked product is crushed by rotating the plastic bottle. Then, it is taken out from the plastic bottle and passed through a nylon 200 mesh screen to remove the phosphor of large particles. Then, it is decanted, dried, and passed through a sieve to obtain a phosphor having the following composition. (Y _0.95 , Tb _0.02 , Ce
_0.01 , Eu _0.02 ) ₂ SiO ₅ was obtained.

[Examples 2 to 10] In the same manner as in Example 1, the phosphor raw materials were mixed in the stoichiometric ratio of the intended composition and synthesized in the same manner to obtain phosphors having the compositions shown in Table 1.

[Comparative Example 1] Y ₂ S as a green light emitting phosphor
iO ₅ : Tb 25.0%, Y ₂ as a blue light emitting phosphor
SiO ₅ : Ce 53.0%, Y as a red light emitting phosphor
₂ 0 _3: Eu are mixed with 19.0% and monochrome phosphor for FED of Comparative Example.

[0015]

[Table 1]

The measurement conditions in this table are as follows: the acceleration voltage of the electron beam for exciting the phosphor is 3 kV, and the current density is 1.5 mA / cm.
^It is set to ² and the measured value in the FED real sphere is shown. Differences between the chromaticity values x and y of Examples 1 to 4 and Comparative Example 1 and the initial chromaticity value under the same conditions as the electron beam after 1000 hours were represented by Δx and Δy.

It can be said that the smaller the values of Δx and Δy, the more excellent the color misregistration. As is clear from Table 1, the phosphors of the present invention obtained in the examples have good results with respect to color misregistration as compared with the comparative examples.

[0018]

The monochrome phosphor for FED of the present invention is
By adjusting the amounts of Tb, Ce, and Eu in the composition formula, the color reproduction range can be remarkably widened. The phosphors of the examples of the present invention shown in Table 1 have an x value of 0.180 to 0.64 in the chromaticity diagram.
0 and the y value is 0.170 to 0.580. This range includes blue, white, red, and green, indicating that the phosphor of the present invention can emit a very wide range of colors.
Furthermore, the fluorescent substance of the present invention has extremely small Δx and Δy of 1 to 2 which show a color shift after 1000 hours of lighting. This value is significantly smaller than the conventional phosphors having Δx and Δy of 5 to 10, indicating that the change in emission color is extremely small. Therefore, the monochrome phosphor of the present invention has a feature of exhibiting ideal light emission characteristics for FED.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyoshi Tamura             629 Oshiba, Mobara-shi, Chiba Futaba Electronics Co., Ltd.             In the company F-term (reference) 4H001 XA08 XA14 XA39 YA58 YA59                       YA62 YA63 YA65

Claims (7)

[Claims] 1. A monochrome phosphor for an FED, characterized in that a general formula of composition is represented by the following formula. (Y _1-p-q-r-s-t , Tb _p , Ce _q , E
_{u r, Sm s, Pr t} ) 2 Si a O 3 + 2a 0.001 ≦ p ≦ 0.20 0.0005 ≦ q ≦ 0.05 0 ≦ r ≦ 0.20 0 ≦ s ≦ 0.15 0 ≦ t ≦ 0.05 0.5 ≦ a ≦ 1.0 2. The monochrome phosphor for an FED according to claim 1, wherein the composition contains at least two or more elements out of Tb, Ce, Eu, Sm and Pr. 3. The monochrome phosphor for FED according to claim 1, wherein the value of p in the composition formula is in the following range. 0.01 ≤ p ≤ 0.04 4. The monochrome phosphor for FED according to claim 1, wherein the value of q in the composition formula is in the following range. 0.001 ≦ q ≦ 0.02 5. The monochrome phosphor for FED according to claim 1, wherein the value of r in the composition formula is in the following range. 0 ≦ r ≦ 0.02 6. The monochrome phosphor for FED according to claim 1, wherein the value of s in the composition formula is in the following range. 0 ≦ s ≦ 0.02 7. The monochrome phosphor for FED according to claim 1, wherein the value of t in the composition formula is in the following range. 0 ≦ t ≦ 0.02