JPH1077471A - Display - Google Patents

Abstract

(57) [Summary] To provide a high-performance electron beam excitation display device. An MP _a V _1-a O _4, or _{M 1-a Eu a P b} V 1-b
O _{4 where} M is a phosphor comprising at least one element selected from the group consisting of yttrium, scandium, rare earth elements of atomic numbers 57 to 62, 64 to 71, and Group IIb elements of the periodic table. Light is emitted by an electron beam accelerated to 0.1 to 10 KV.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying information according to an electric signal.

[0002]

2. Description of the Related Art In addition to a liquid crystal display, a matrix display which displays an image by adjusting the voltage applied to each pixel to the intersection of the electrode groups orthogonal to each other is a field emission display (F).
ED) and plasma display (PDP). For example, as described in Japanese Patent Application Laid-Open No. 4-289644, an FED arranges a large number of minute field emission cathodes in each pixel, accelerates the field emission electrons therefrom in a vacuum, and then irradiates the phosphor with the electrons. And emit light.

In the FED, a distance between a phosphor plate coated with a phosphor and an electron emission source is usually set to about 0.2 to several mm.
Therefore, the accelerating voltage Va applied to the fluorescent screen is 100 V or more.
10KV. This is because if it is more than this, dielectric breakdown occurs between the electron emission source and the fluorescent plate.

Many phosphors excited by an electron beam have been developed for a cathode ray tube (CRT). In a CRT, an acceleration voltage is about 20 to 30 KV, and a phosphor has been developed in accordance with the acceleration voltage.

[0005]

Some phosphors optimized for low- and medium-speed electron beam excitation of 100 V to 10 KV have been developed. However, the luminous efficiency of these phosphors is not yet sufficient. For example, in the literature (First International
Conference on the Science and Technology of Display
Phosphors, Extended Abstracts (1995.11, San Dieg
o, California) p.
A list of emission characteristics of various phosphors when used at KV acceleration is listed. As you can see from this list,
Among the low-speed / medium-speed electron-beam accelerated phosphors, the one having the highest luminous efficiency at present is ZnS: Ag for the blue light-emitting phosphor and Y ₂ O ₂ S: Eu for the red light-emitting phosphor.

[0006] All of these phosphors contain sulfur (S) as a constituent element. When these phosphors are actually mounted on an FED, it is known that the phosphors are decomposed by electron beam irradiation to generate sulfur, which adheres to the surface of the electron source and significantly reduces the electron emission ability. This is a major problem in realizing the display FED. There is also a problem that the phosphor itself is deteriorated by decomposition.

[0007] In order to avoid this problem, a phosphor containing no sulfur as a constituent element may be used. Among the known phosphors, those containing no sulfur are compared with the above-mentioned phosphors. Therefore, the luminous efficiency is 1/2 to 1/10 or less, which is problematic in terms of luminous efficiency.

[0008]

According to the present invention, there is provided a compound having a general composition formula M
P _a V _1-a O ₄ (where M is yttrium (Y), scandium (Sc), rare earth elements of atomic numbers 57 to 62, 64 to 71, and group IIb elements of the periodic table) A blue light-emitting phosphor containing at least one selected element, a self-activated phosphor represented by 0 <a <1), or a general composition formula M _1-a Eu _a P _b V _1-b O ₄ (where M is yttrium (Y), scandium (Sc), atomic number 57-
No. 62, No. 64 to No. 71 rare earth element, and at least one element selected from the group of Group IIb elements of the periodic table, trivalent represented by 0 <a <1,0 <b <1) The above problem is solved by causing a red light-emitting phosphor containing a phosphor activated by europium to emit light with an electron beam accelerated to 0.1 to 10 KV.

The main reason why the luminous efficiency of the low-speed / medium-speed electron beam-excited phosphor is low is that the electron beam cannot penetrate deep into the phosphor. The depth R into which the electron beam having energy E enters the phosphor is proportional to E raised to the nth power. n is a number determined by the atomic number of the constituent element of the phosphor. For example, in the case of ZnS, n = 1.98. R in the case of a phosphor whose main body is ZnS is E = 20 KV, 10 KV, 4 KV, 1 KV
At the time of 5.9 μm, 1.5 μm, 0.24 μm, 0.2 μm, respectively.
015 μm. The particle size of the phosphor is usually 2 to 6 μm
Therefore, it can be seen that when E ≦ 10 KV, the electron beam enters only the surface of the phosphor.

Since the phosphor is not excited in the portion where the electron beam does not enter, the contribution to light emission is small. Considering the distribution of light emitting sites within the phosphor, the actual phosphor has fewer light emitting sites near the surface than inside the phosphor. This is because the composition or state of the surface changes due to a chemical reaction or the like in the process of manufacturing the phosphor or in the process of coating the phosphor plate. Therefore, compared to fast electron beam excitation,
In the case of low-speed / medium-speed electron beam excitation, the luminous efficiency is greatly reduced. In other words, in the case of low-speed / medium-speed electron beam excitation, the surface state is hardly deteriorated by the manufacturing / coating process, and it is necessary to use a stable phosphor.

The reason that only the phosphor surface contributes to the excitation is the same in the case of the ultraviolet-excited phosphor. Therefore, an ultraviolet-excited phosphor having a stable surface state is used. That is, the ultraviolet-excited phosphor satisfies one of the required characteristics of the low-speed / medium-speed electron beam-excited phosphor. As a result of various experiments in this light, the general formula _{MP a V 1-a O 4} , or the general formula _{M 1-a Eu a P b} V 1-b O 4 becomes phosphor,
It has been found that it has excellent characteristics as a low-speed / medium-speed electron-beam excited phosphor.

These phosphors are disclosed in JP-A-50-67782,
As disclosed in JP-A-50-67783, it has excellent properties as an ultraviolet-excited phosphor. One of the phosphors represented by this general formula, for example, a blue phosphor (Y, G
d) P _0. The ₈₅ V _{0. 15} O _4, to create a fluorescent plate of methanol and precipitated applied as a solvent, 0.5 the acceleration voltage E of the electron beam
FIG. 2 shows the luminance when changing in the range of 4 KV.
It was shown to. The average current density of the irradiated electron beam is 0.5 μA
/ Cm ² .

ZnS: Ag, which is a blue phosphor excited by a low-speed / medium-speed electron beam and has the highest luminous efficiency, is 51 cd / m ² at 4 KV acceleration and a current density of 1 μA / cm ² . Assuming that the current density is 1 μA / cm ² , the phosphor is 44 cd / E = 4 KV.
m ² , the luminous efficiency is almost the same as that of ZnS: Ag. The low- and medium-speed electron-beam phosphors containing no sulfur have higher luminous efficiency than any of the blue phosphors reported so far.

FIG. 3 plots the relative luminous efficiency of the phosphor, that is, the value obtained by dividing the luminance by the energy of the electron beam (current × acceleration voltage). FIG. 3 shows a relative value based on the value at E = 1 KV. Even at E = 500V, the efficiency is reduced only to about 1/3 of E = 4KV. The aforementioned Zn
For the S: Ag phosphor, the luminous efficiency at E = 300 V is
Taking into account that it is reduced to {fraction (1/10)} = 4 KV, it indicates that the present phosphor is a highly efficient phosphor even in a low-speed electron beam region where the acceleration voltage is several hundred volts.

Thus, the general composition formula MP _a V _1-a O ₄ ,
Alternatively, the phosphor represented by the general composition formula M _1-a Eu _a P _b V _1-b O ₄ has high luminous efficiency as a low-speed / medium-speed electron beam-excited phosphor of several hundred volts to 10 kV, and has sulfur as a constituent element. , No sulfur is generated during operation, and therefore, the characteristics of the electron source are not deteriorated. In addition, since the phosphor does not decompose during operation unlike a phosphor containing ZnS as a base, a long-life FED can be realized.

The general composition formula _{Y 1-ax M x Tb a} P b V 1-b O
₄ (where M is gadolinium (Gd) or lanthanum (La), and a phosphor represented by 0 ≦ x <1, 0 <a <1, 0 <b <1) is disclosed in JP-A-50-67782. Kaisho 50-6778
Although it is not described in Japanese Patent Publication No. 3 (1999), the essential point of the present invention is the surface stability of the base material of the phosphor. Therefore, even when the activator contributing to light emission is changed from Eu ³⁺ to Tb ³⁺ , the same applies. The effect is obtained. T as activator
When b ³⁺ is used, green light emission is obtained.

[0017]

FIG. 1 is a sectional view of a display device according to an embodiment using the present invention. A face plate 110 made of a translucent material such as glass and an insulating substrate 10 such as glass
The layers are overlapped with an interval of about 0 μm, the periphery is sealed to form a closed structure, and the inside is kept at a vacuum 55.

A metal such as Al or Mo is formed on the substrate 10 in a stripe shape to form a cathode bus line 21. A protective resistance layer 22 is formed thereon by forming amorphous Si by a chemical vapor deposition method. An insulating layer 543 having a thickness of 0.5 to 1.5 μm is formed thereon, and Mo, Ta is further formed thereon.
For example, a plurality of gate electrodes 545 parallel to each other are formed so as to be orthogonal to the cathode bus lines 21. The intersection of the cathode bus line 21 and the gate electrode 545 becomes a pixel. The gate electrode 545 and the insulating layer 5 are formed by using photolithography.
A hole having a diameter of about 1 μm is formed in the hole 43. About 10 ³ to 10 ⁴ holes are formed in one pixel. Next, Ni is formed on the gate electrode 545 to form a separation layer (not shown in FIG. 1).
And At this time, by using oblique evaporation, Ni is prevented from entering the previously formed holes. Thereafter, Mo is deposited to form an emitter chip 542.
Thereafter, the field emitter array as shown in FIG. 1 is formed by removing the separation layer and the Mo deposited on the separation layer by etching. The method of creating the field emitter array is described in, for example,
This is described in more detail in Japanese Patent Application No. -221783.

On the face plate 110, ITO (Indium Tin O
xide) or the like, and an acceleration electrode 112 made of a light-transmitting conductive electrode material is formed. A red light emitting phosphor 114A, a green light emitting phosphor 114B, and a blue light emitting phosphor 114C are formed on the acceleration electrode 112. Each phosphor 114 is patterned into a shape corresponding to the cathode bus line 21 so that the electrons emitted from the emitter chip 542 on each pixel are irradiated on the phosphor of each color.

[0020] YP ₀ is as red light-emitting phosphor 114A. _{65
V 0 35 O 4:. Eu} , as the green phosphor ZnO:. Zn, as a blue emitting phosphor _{114C (Y, Gd) P 0} 85 V 0.
₁₅ O ₄ was used. These phosphors were patterned by screen printing. The thickness of the phosphor 114 is 5 μm to 50 μm.
m.

In order to make the phosphor conductive,
Red light emitting phosphor 114A and blue light emitting phosphor 114C
Mixed with 10 wt% of In ₂ O ₃ may be used. When the phosphor is made conductive in this manner, a charge-up effect due to an electron beam can be prevented. Therefore, there is an effect of reducing luminance saturation and increasing luminance particularly when the acceleration voltage is low.

By sandwiching beads having a diameter of 200 μm between the face plate 110 and the substrate 10 prepared in this manner, the beads are superimposed at an interval of 200 μm, and
10. The peripheral portion of the substrate 10 is sealed with frit glass. The inside of the panel thus manufactured is evacuated to a vacuum to complete the panel.

An acceleration voltage of about 400 V is applied to the acceleration electrode 112. The gate electrode 545 is used as a scanning electrode, and 8
A voltage of about 0 V is applied. The cathode bus line 21 includes
A voltage of about 0 to 30 V is applied according to the displayed image. The larger the voltage applied between the gate electrode 545 and the cathode bus line 21 for a pixel, the more the emitter chip 54 on that pixel
The current of electrons emitted from 2 increases. This electron is
The phosphor 114 is accelerated by the accelerating voltage and is irradiated on the phosphor 114. In this way, since the phosphor 114 at the location corresponding to the pixel emits light, an image is displayed.

Next, another embodiment using the present invention will be described with reference to FIGS.
This will be described with reference to FIGS. FIG. 4 is a sectional structural view of the display device of the present embodiment. A spacer 60 having a thickness of about 2 mm is sandwiched between a face plate 110 made of a light-transmitting material such as glass and an insulating substrate 10 such as glass, and is superposed.
The periphery is sealed to form a closed structure, and the inside is kept at a vacuum 55.

First, a method of manufacturing an electron emission portion on the substrate 10 will be described. Al is formed on the substrate 10 by rf sputtering or the like, and is patterned by photolithography to form the lower electrode 11. Subsequently, the MIM insulating layer 12 is formed to a thickness of about 5 to 10 nm by anodic oxidation. Next, an insulating layer such as SiO ₂ is formed by a method such as sputtering to form the electrode end protection layer 15. The electrode end protection layer 15
This prevents the electric field from concentrating at the end of the lower electrode 11 to cause dielectric breakdown, and has a function of extending the life of the element.

Next, a film thickness of 1 nm is formed by sputtering.
Ir, Pt having a thickness of 2 nm, and Au having a thickness of 3 nm are sequentially laminated to form an upper electrode 13. The upper electrode 13 is formed only at the intersection with the lower electrode, as shown in FIG. Then, A
A material having high conductivity, such as u, having a film thickness of 50 in the pattern of FIG.
The upper electrode bus line 32 is formed to a thickness of about 0 nm. By forming the upper electrode bus line 32 in a pattern thinner than the upper electrode 13 as shown in FIG.
Since the electric capacitance between the lower electrode 2 and the lower electrode 11 becomes smaller,
High-speed driving of the element is facilitated.

On the face plate 110, ITO (Indium Tin O
xide) or the like, and an acceleration electrode 112 made of a light-transmitting conductive electrode material is formed. A red light emitting phosphor 114A, a green light emitting phosphor 114B, and a blue light emitting phosphor 114C are formed on the acceleration electrode 112. FIG. 5 shows the coating pattern of each phosphor. Each phosphor 114 is patterned in a shape corresponding to the upper electrode bus line 32. The pattern of the phosphor 114 in FIG. 4 does not match the pattern in FIG. 5, but is illustrated in FIG. 4 in order to clearly show that a plurality of types of phosphors are used. Further, the present invention is not limited to the pattern on the stripe as shown in FIG.

[0028] The red light-emitting phosphor 114A is YP _{0. 65} V _{0. 35}
O ₄ : Eu, the green phosphor is Zn ₂ SiO ₄ : Mn (P1-G
1) The blue light emitting phosphor 114C is (Y, Gd) P ₀ .
The ₈₅ V _{0. 15} O ₄ was used. These phosphors were patterned by screen printing. The thickness of the phosphor 114 is 5 μm
５０50 μm. If the thickness is smaller than this, some of the electrons incident on the phosphor screen enter the acceleration electrode 112 without hitting the phosphor particles, and the luminous efficiency deteriorates. Conversely, if the thickness is larger than this, the phosphor screen is likely to be charged up by the electron beam, and the luminous efficiency is rather reduced.

By interposing a spacer 60 having a thickness of about 1 to 2 mm between the face plate 110 and the substrate 10 thus formed, they are superposed at an interval of 1 to 2 mm.
The peripheral portions of the face plate 110 and the substrate 10 are sealed with frit glass. The inside of the panel thus manufactured is evacuated to a vacuum to complete the panel. The spacer 60 is formed by punching holes in non-alkali glass or ceramics by a sand blast method or the like. Spacer 6
The hole pattern of 0 is shaped as shown in FIG.
0 does not contact the upper electrode 13.

An acceleration voltage of about 2 KV to 4 KV is applied to the acceleration electrode 112. A scanning pulse of about −5 V is applied to the lower electrode 11, and a signal voltage of 0 to 5 V is applied to the upper electrode bus line 32 corresponding to an image signal. In a pixel in which a voltage of 5 V or more is applied between the upper electrode 13 and the lower electrode 11, an electric field applied in the MIM insulating layer 12 causes
The electrons in the lower electrode 11 pass through the upper electrode 13 by a tunnel phenomenon. Some of these tunnel electrons pass through the upper electrode 13 and are radiated into the vacuum 55. The electrons emitted in the vacuum are accelerated by the accelerating voltage and
And the phosphor emits light. Upper electrode 1
Since the amount of electrons emitted to the vacuum 55 increases as the voltage between the lower electrode 11 and the lower electrode 11 increases, the upper electrode bus line 3
By adjusting the voltage applied to 2, an image can be displayed.

Further, as in this embodiment, the acceleration voltage is set to 4K.
In the case of a medium electron beam region of about V, the phosphor 114
An Al film may be formed on the vacuum side, that is, the side on which the electron beam enters. Specifically, after applying the phosphor 114, a filming material such as cellulose is applied, and Al is formed to a thickness of about 100 to 250 nm by an evaporation method. Thereafter, when the face plate is heated to 450 ° C., the filming material is thermally decomposed and disappears.
The film remains. In addition, a porous Al film is obtained in this manner, and the electron beam transmittance is improved. When the Al film is formed in this manner, charge-up of the phosphor due to electron beam irradiation can be prevented, so that the luminance saturation is reduced and the life is prolonged. Furthermore, of the light emitted in the phosphor 114, light that escapes to the vacuum side, that is, the side opposite to the observer, is reflected by the Al film and is extracted to the observer side, so that a substantial display device is provided. Brightness is improved.

[0032]

According to the present invention, an electron-beam-excited display device having high luminous efficiency and long life can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a display device according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram of emission luminance of a phosphor used in the present invention and an acceleration voltage of electrons.

FIG. 3 is a characteristic diagram showing the acceleration voltage dependence of the relative luminous efficiency of the phosphor used in the present invention.

FIG. 4 is a sectional view of a display device according to a second embodiment of the present invention.

FIG. 5 is a plan view showing an application pattern of a phosphor and a shape of a spacer in a second embodiment.

FIG. 6 is a plan view showing a pattern of a lower electrode, an upper electrode, and an upper electrode bus line in the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... board | substrate, 21 ... cathode bus line, 22 ... protective resistance layer, 55 ... vacuum, 110 ... face plate, 112 ... acceleration electrode, 1
14 phosphor, 542 emitter tip, 543 insulating layer, 545 gate electrode.

Claims (10)

[Claims] 1. A general composition formula: MP _a V _{1 -a} O ₄ (where M is yttrium (Y), scandium (Sc), atomic number 57-)
The self-activated phosphor represented by 0 <a <1) containing at least one element selected from the group consisting of the 62nd and 64th to 71st rare earth elements and the group IIb element of the periodic table. A display device, wherein a blue light emitting screen emits light with an electron beam accelerated to 0.1 KV to 10 KV. 2. A general composition formula _{M 1-a Eu a P b} V 1-b O 4 ( wherein M is yttrium (Y), scandium (Sc), atomic number 57 No. No. - 62, the No. 64 No. to 71 Phosphor activated by trivalent europium represented by a rare earth element and at least one element selected from the group consisting of group IIb elements of the periodic table, 0 <a <1,0 <b <1) A display device characterized in that a red light-emitting screen containing is emitted by an electron beam accelerated to 0.1 KV to 10 KV. 3. A general composition formula: MP _a V _{1 -a} O ₄ (where M is yttrium (Y), scandium (Sc), atomic number 57-)
A self-activated phosphor represented by 0 <a <1) selected from the group consisting of a rare earth element of Nos. 62, 64 to 71, and a group IIb element of the periodic table; 0.1 KV to 1
A display device which emits light with an electron beam accelerated to 0 KV. 4. The general composition formula _{M 1-a Eu a P b} V 1-b O 4 ( wherein M is yttrium (Y), scandium (Sc), atomic number 57 No. No. - 62, the No. 64 No. to 71 Phosphor activated by trivalent europium represented by a rare earth element and at least one element selected from the group consisting of group IIb elements of the periodic table, 0 <a <1,0 <b <1) 0.1KV to 10KV red light emitting screen mixed with conductive material
A display device characterized in that light is emitted by an electron beam accelerated to a high level. 5. The method according to claim 1, wherein said conductive material is In ₂ O ₃ or S
5. The display device according to claim 3, wherein a material containing nO ₂ is used. 6. A general composition formula (Y _1-x M _x ) P _a V _1-a O ₄ (where M is gadolinium (Gd) or lanthanum (La),
A display device wherein a blue light-emitting screen containing a self-activating phosphor represented by 0 ≦ x <1, 0 <a <1) emits light with an electron beam accelerated to 0.1 to 10 KV. 7. The general composition formula _{Y 1-ax M x Eu a} P b V 1-b O
₄ (M is gadolinium (Gd) or lanthanum (L
a), accelerating a red light-emitting screen containing a phosphor activated with trivalent europium represented by 0 ≦ x <1, 0 <a <1, 0 <b <1) to 0.1 KV to 10 KV A display device, wherein the display device emits light with an electron beam. 8. The general composition formula _{Y 1-ax M x Tb a} P b V 1-b O
₄ (where M is gadolinium (Gd) or lanthanum (La), fluorescence activated by trivalent terbium (Tb) represented by 0 ≦ x <1, 0 <a <1, 0 <b <1) A green light-emitting screen containing a body is 0.1 KV to 10 KV
A display device characterized in that light is emitted by an electron beam accelerated to a high level. 9. An aluminum film is formed on an electron beam incident side of said phosphor screen.
9. The display device according to 6, 7, or 8. 10. A phosphor screen having a thickness of 5 μm or more and 50 μm or less.
9. The display device according to 6, 7, or 8.