JPH05251023A - Phosphor screen of field emission display - Google Patents

Abstract

PURPOSE:To provide a highly intensified phosphor screen of a field emission display which has a phosphor screen to be excited by a medium-speed electron beam of approximately 0.1-2kV. CONSTITUTION:In a field emission display which is provided with at least an electron beam acceleration part and a cathode on the back of a phosphor screen comprising phosphor applied thereto and has such a structure as exciting the phosphor screen by means of an electron beam of accerelation voltage of 0.1-2kV so as to let it emit light, said phosphor screen is subjected to application of phosphor of 0.1mum-4mum in center particle size and 0.2mg/cm<2>-3.0mg/cm<2> in amount of application.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent film for a flat panel display, and more particularly to a fluorescent film having a field emission cathode and an anode facing the field emission cathode. The present invention relates to a fluorescent film of a field emission display having a structure that emits light when excited by a line.

[0002]

2. Description of the Related Art Recently, flat panel displays have been studied by many manufacturers and research institutes. Among them, field emission displays (Field Emission Cathode) are used.
Is called). A field emission cathode is a type of cold cathode cathode, and some of them have already been announced. {Proceedings of the 38th Joint Lecture on Applied Physics,
No.2, p525, (1991), Proceedings of the 52nd Joint Lecture on Applied Physics, No.2, p505, (1991)}

The structure of the FED will be briefly described with reference to FIG.
This is basically a field emission cathode (FE cathode),
A flat panel display having a structure having an anode facing it and exciting a fluorescent film provided on the anode side with an electron beam of a medium speed accelerating voltage to emit light.
Electrons emitted from the field emission cathode are accelerated by the anode at a medium speed of about 0.1 to 2 kV to excite a phosphor film formed by coating a phosphor on a front glass plate on the anode side to emit light.

[0004]

The above-mentioned structure of the F
In order to compete with other flat panel displays such as plasma displays and liquid crystal displays in EDs, it is necessary to increase the brightness of the FED itself, and most of the factors that increase the brightness depend on the characteristics of the fluorescent film. ..

As described above, since the FED fluorescent film is excited by an electron beam having an accelerating voltage of 0.1 to 2 kV and a relatively medium speed, the penetration depth of the phosphor into the electron beam is relatively shallow. Therefore, in order to obtain a brightness comparable to that of a CRT, the fluorescent film is excited by an electron beam having a high current density. Therefore, the phosphor constituting the fluorescent film is required to have a high brightness with a medium-speed electron beam.

However, the FED fluorescent film itself has not been well researched, and it is not known well yet what kind of fluorescent substance and how to apply it to obtain a fluorescent film with high brightness. is there.

Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide an FED having a fluorescent film excited by a medium-speed electron beam of about 0.1 to 2 kV. It is intended to provide a fluorescent film with high brightness.

[0008]

In order to improve the brightness of the FED, the inventors of the present invention conducted various experiments on the fluorescent film of the FED, and as a result, reduced the particle size of the fluorescent substance forming the fluorescent film. It has been found that the above object can be achieved by increasing the surface area and applying a thinner layer, thus completing the present invention.

That is, the fluorescent film of the FED according to the present invention has at least a field emission cathode and an anode facing the field emission cathode, and the fluorescent film provided on the anode side is about 0.1 to 10.
In the FED having a structure that emits light by being excited by an electron beam having a medium-speed acceleration voltage of 2 kV, the phosphor film has a central particle size of 0.1 μm or more and 4 μm or less of 0.2 mg / cm ²
As described above, it is characterized in that the coating amount is 3.0 mg / cm ² or less. In the present invention, the central particle size means a particle size corresponding to 50% of the cumulative distribution in the particle size distribution of the phosphor measured by the Coulter counter method,
Generally expressed as a D50 value.

The phosphor that can be used to obtain the above-mentioned phosphor film may be any phosphor as long as it is a phosphor for a cathode ray tube that is excited by an electron beam to emit light. For example, as a blue-emitting phosphor, ZnS: Ag, X fluorescence is used. Body, Y ₂ SiO ₅ : Ce phosphor, LnOX: Ce phosphor (Ln is a rare earth element, X is Al, or a halogen element), and Z is a green light emitting phosphor.
nS: Cu, X phosphor, Y ₃ Al ₅ O ₁₂ : Tb phosphor, Y ₃
(Al, Ga) ₅ O ₁₂ : Tb phosphor, Y ₂ SiO ₅ : Tb phosphor, Y ₂ O ₂ S: Eu phosphor as a red light emitting phosphor, Y
₂ O ₃ : Eu phosphor, Y ₂ O ₂ S: Eu, Sm phosphor and the like can be preferably used. Particularly, as a blue light emitting phosphor, Ag is 300 ppm or more with respect to the base material, 1500 pp.
ZnS: Ag, X (where X is A
1, at least one of halogen elements) phosphor can be preferably used, and ZnS: Cu, X phosphor containing Au in the range of 200 ppm or more and 1500 ppm or less with respect to the matrix as a green-emitting phosphor, or Au. 200 pp of ZnS: Au, X phosphor or Cu contained in the range of 200 ppm or more and 1500 ppm or less with respect to the base material
m to 1500 ppm and Au to 100 ppm
ZnS: Cu, Au, X phosphor containing 600 ppm or less can be preferably used, and Y ₂ O ₂ S containing Eu in the range of 1% or more and 10% or less with respect to the host as a red light emitting phosphor: Eu phosphor or Y ₂ O ₃ : Eu phosphor can be preferably used.

[0011]

Function: As shown in FIG. 2, the median particle diameter is 0.5 μm, 1 μm, 2.5.
μm, 4 μm, 8 μm ZnS: Ag, Al blue light emitting phosphor (Ag activation amount: 650 ppm based on ZnS matrix)
Is applied to a glass plate while changing the coating amount, and when the fluorescent film of the glass plate is excited by various accelerating voltages, the relationship between the fluorescent substance coating amount in each fluorescent film and the brightness of the fluorescent film, The figure which compares and shows with each accelerating voltage is shown. 2, FIG. 2-A shows an acceleration voltage of 20 kV, FIG. 2-B shows the same 4 kV, FIG. 2-C shows 2 kV, FIG. 2-D shows 0.5 kV, FIG. 2-E shows 0.3 kV, and FIG. Is a diagram when the phosphor film is excited at 0.1 kV. In each figure, the relative brightness of each phosphor film is 100% when the phosphor having a central particle diameter of 8 μm is applied at the optimum application amount. Show.

As shown in A to B, the larger the particle size of the phosphor, the higher the brightness at a high accelerating voltage.
As shown in F, the brightness of the phosphor having a smaller particle size tends to increase as the accelerating voltage decreases, and the phosphor is used in the accelerating voltage range of 0.1 kV to 2 kV of the phosphor for FED. It can be seen that the brightness is higher when the particle size is less than 4 μm.

Also in FIG. 3, the central particle size is 0.5 μm,
1 μm, 2.5 μm, 4 μm, 8 μm ZnS: Cu,
Al green light emitting phosphor (Cu activation amount: 4 with respect to ZnS matrix)
(00 ppm) is applied to a glass plate with different coating amounts, and when the fluorescent film of the glass plate is excited by various acceleration voltages, the relationship between the fluorescent substance coating amount of each fluorescent film and the brightness of the fluorescent film is shown. , Shows a diagram for comparison at each accelerating voltage. Similarly, in FIG. 3, FIG. 3-A shows an acceleration voltage of 20 kV, and FIG.
B is 4 kV, FIG. 3-C is 2 kV, and FIG. 3-D is 0.
5kV, 0.3kV in Figure 3-E, 0.1kV in Figure 3-F
FIG. 3 is a diagram when the phosphor film is excited by, and in each figure, the relative brightness of each phosphor film is shown assuming that the brightness when a phosphor having a central particle diameter of 8 μm is applied at an optimum application weight is 100%.

As in the previous figure, in the green light emitting phosphor, the larger the particle size of the phosphor is, the higher its brightness is in the place where the acceleration voltage is high, and the smaller the particle size is as the acceleration voltage is lower. It can be seen that the brightness tends to increase, and that the brightness is higher when the particle size of the phosphor is 4 μm or less in the acceleration voltage range of 0.1 kV to 2 kV of the FED phosphor.

In FIG. 4, ZnS: Ag, A having a central particle size of 2.5 μm was manufactured by changing the activation amount of Ag with respect to the ZnS matrix.
l The blue light-emitting phosphor is applied to a glass plate at an optimum coating amount at each accelerating voltage to form a phosphor film, and when each phosphor film is excited at various accelerating voltages, the activation of Ag on the ZnS matrix is activated. The figure which shows the relationship between quantity and the brightness | luminance of the fluorescent film in comparison with each accelerating voltage is shown. Fig. 4-A shows an acceleration voltage of 20 kV, Fig. 4-B shows 4 kV, and Fig. 4-C shows 2 kV.
V, FIG. 4-D is 0.5 kV, FIG. 4-E is 0.3 kV, and FIG. 4-F is a diagram when the fluorescent film is excited at 0.1 kV. In each figure, the relative of each fluorescent film is shown. The brightness is A
g Brightness when applying phosphor with an activation amount of 300 ppm is 1
Shown as 00%.

FIG. 5 shows ZnS: Cu, A having a central particle diameter of 2.5 μm, which was produced by changing the activation amount of Cu with respect to the ZnS matrix.
The green light emitting phosphor was applied to the glass plate at the optimum coating amount at each accelerating voltage as before to form a phosphor film, and when each phosphor film was excited at various accelerating voltages, Cu for the ZnS matrix was formed. FIG. 6 is a diagram showing the relationship between the activation amount of Pt and the brightness of the phosphor film thereof at each accelerating voltage.
Also in FIG. 5, FIG. 5-A shows an acceleration voltage of 20 kV, FIG. 5-B shows 4 kV, FIG. 5-C shows 2 kV, and FIG.
kV, FIG. 5-E is 0.3 kV, and FIG. 5-F is a diagram when the fluorescent film is excited at 0.1 kV. In each figure, the relative brightness of each fluorescent film is 200 ppm of Cu activation amount. The luminance when the phosphor is applied is shown as 100%.

In FIG. 6, ZnS: Au, A having a central particle size of 2.5 μm was manufactured by changing the activation amount of Au with respect to the ZnS matrix.
The green light emitting phosphor was coated on a glass plate at the optimum coating amount at each acceleration voltage to form a phosphor film, and when each phosphor film was excited at various acceleration voltages, Au for ZnS matrix was formed. FIG. 6 is a diagram showing the relationship between the activation amount of Pt and the brightness of the phosphor film thereof at each accelerating voltage.
Similarly, in FIG. 6, FIG. 6-A shows an acceleration voltage of 20 kV, FIG. 6-B shows 4 kV, FIG. 6-C shows 2 kV, and FIG. 6-D shows 0.5 kV.
kV, FIG. 6-E is 0.3 kV, and FIG. 6-F is a diagram when the fluorescent film is excited at 0.1 kV. In each drawing, the relative luminance of each fluorescent film is Au activation of 200 ppm. The luminance when the phosphor is applied is shown as 100%.

FIG. 7 shows Y ₂ O ₂ S: Eu having a central particle diameter of 2.5 μm, which was produced by changing the activation amount of Eu with respect to the Y ₂ O ₂ S matrix.
When the red light emitting phosphor is applied to the glass plate at the optimum coating amount at each accelerating voltage as before to form a phosphor film and each phosphor film is excited by various accelerating voltages, Y ₂ O ₂ S The figure which shows the relationship between the activation amount of Eu with respect to a base | substrate and the brightness | luminance of the fluorescent film in comparison with each accelerating voltage is shown.
Similarly, in FIG. 7, the acceleration voltage is 20 kV in FIG. 7-A, 4 kV in FIG. 7-B, 2 kV in FIG. 7-C, and 0.5 in FIG. 7-D.
kV, FIG. 7-E is 0.3 kV, and FIG. 7-F is a diagram when the fluorescent film is excited at 0.1 kV. In each figure, the relative luminance of each fluorescent film is 1% Eu activation. The luminance when the above phosphor is applied is shown as 100%.

FIG. 8 shows a Y ₂ O ₃ : Eu red light-emitting phosphor having a central particle size of 2.5 μm, which was produced by changing the activation amount of Eu with respect to the Y ₂ O ₃ matrix, at each accelerating voltage as before. Apply the optimum amount of coating to each glass plate to create a fluorescent film,
When each fluorescent film is excited with various acceleration voltages,
The relationship between Y ₂ O ₃ amount of Eu to the parent and the luminance of the phosphor film shows a diagram representing, compared with the accelerating voltage. Similarly, in FIG. 8, FIG. 8-A shows an acceleration voltage of 20 kV, and FIG.
Is 4 kV, FIG. 8-C is 2 kV, and FIG. 8-D is 0.5 kV.
FIG. 8-E is a diagram when the fluorescent film is excited at 0.3 kV, and FIG. 8-F is a diagram when the fluorescent film is excited at 0.1 kV. In each figure, the relative luminance of each fluorescent film is the fluorescence with the Eu activation amount of 1%. The brightness when the body is applied is shown as 100%.

In FIG. 4, the ZnS: Ag, Al phosphor is the acceleration voltage range (AB) used in a normal CRT.
Then, even if the concentration of the activator Ag is increased, the brightness of the phosphor film is hardly changed or slightly increased, but in the accelerating voltage range of the phosphor for FED shown in C to F, The optimum value of the brightness appears depending on the activation amount of Ag of the activator, and the activation amount is preferably 300 ppm to 1500 ppm, more preferably 400 to 1200 ppm.

Similarly in FIG. 5, the FEs shown in C to F are also shown.
In the acceleration voltage range of the phosphor for D, ZnS: Cu, A
The optimum value of the brightness appears depending on the Cu activation amount of the l phosphor, and the activation amount is preferably 200 ppm to 1500 ppm,
The range of 300 to 1200 ppm is more preferable.

Similarly in FIG. 6, the FEs shown in C to F are also shown.
In the accelerating voltage range of the D phosphor, ZnS: Au, A
The optimum value of the brightness appears depending on the activation amount of Au of the l phosphor, and the activation amount is preferably 200 ppm to 1500 ppm,
The range of 300 to 1200 ppm is more preferable.

Similarly in FIG. 7, the FEs shown in C to F are also shown.
In the accelerating voltage range of the D phosphor, the optimum value of the luminance appears depending on the Eu activation amount of the Y ₂ O ₂ S: Eu phosphor, and the activation amount is preferably 1% to 10%, and 3% to The range of 8% is more preferable.

Similarly in FIG. 8, the FEs shown in C to F are also shown.
In the accelerating voltage range of the D phosphor, an optimum value of the brightness appears depending on the Eu activation amount of the Y ₂ O ₃ : Eu phosphor, and the activation amount is preferably 1% to 10%, and 3% to 8%. The range of% is more preferable.

Although not particularly shown, ZnS: Cu,
The green light-emitting phosphor represented by Au, X (where X is at least one of Al and halogen elements) is also shown in FIG.
The same tendency as in FIG. 8 is observed, and in the accelerating voltage range of the FED phosphor, the activation amount of Cu and Au is 2 for Cu.
00ppm or more and 1500ppm or less, Au is 100pp
It is preferably m or more and 600 ppm or less.

[0026]

【Example】

[Examples 1 to 20] A ZnS: Ag, Al phosphor containing 650 ppm of Ag as an activator was trial-produced with a particle size shown in Table 1, and 20 g of the phosphor was sampled.

Next, a solution prepared by dissolving 10 g of HPC (hydroxypropyl cellulose) in 100 ml of water and 100 ml of ethylene glycol was prepared as a binder, and this binder and 20 g of the above-mentioned phosphor were mixed and applied at the ratio shown in Table 1. Create a paste.

The coating paste is screen-coated on a glass substrate, dried, and baked at 500 ° C. to obtain a fluorescent film having the coating amount shown in Table 1. The coating amount is adjusted by the amount of binder mixed.

This fluorescent film is applied with 0.1 kV, 0.3 kV,
When excited by an accelerating voltage of 0.5 kV and 2 kV to emit light, the brightness shown in Table 1 was obtained. Margin below

[0030]

[Table 1]

[0031]

As described above, the median particle diameter of the phosphor constituting the FED phosphor film is 0.1 μm to 4 μm, and the coating amount is 0.2 mg / cm ^{2 to} 3.0 mg / cm ² As a result, it is possible to provide a fluorescent film having excellent emission brightness, and its utility value is great as a fluorescent film for a flat panel display that will be developed in the future.

The fluorescent film of the present invention may be mixed with a conductive oxide such as In, Sn or the like, or the fluorescent substance may be mixed with, adhered to, or coated with a conductive oxide, which is effective in improving the brightness and the life. There is.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing one structure of a field emission display.

FIG. 2 is a diagram showing the relationship between the phosphor coating amount and the brightness of the phosphor film in the phosphor film according to an embodiment of the present invention, comparing the acceleration voltages with each other.

FIG. 3 is a diagram showing the relationship between the phosphor coating amount and the brightness of the phosphor film in the phosphor film according to one embodiment of the present invention, comparing the acceleration voltages with each other.

FIG. 4 is a graph showing the relationship between the activation amount of Ag with respect to the ZnS matrix and the brightness of the phosphor film at each accelerating voltage.

FIG. 5 is a diagram showing the relationship between the activation amount of Cu with respect to the ZnS matrix and the brightness of the phosphor film thereof at each accelerating voltage.

FIG. 6 is a graph showing the relationship between the activation amount of Au with respect to the ZnS matrix and the brightness of the phosphor film, for each acceleration voltage.

FIG. 7 is a diagram showing the relationship between the activation amount of Eu with respect to the Y ₂ O ₂ S matrix and the brightness of the phosphor film, for each acceleration voltage.

FIG. 8 is a diagram showing the relationship between the activation amount of Eu with respect to the Y ₂ O ₃ matrix and the brightness of the phosphor film at each accelerating voltage.

[Procedure amendment]

[Submission date] May 27, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

Claims (2)

[Claims] 1. A structure having at least a field emission cathode and an anode facing the field emission cathode, and having a structure in which a fluorescent film provided on the anode side is excited by an electron beam with an accelerating voltage of about 0.1 to 2 kV to emit light. In the field emission display, the fluorescent film has a central particle diameter of 0.1 μm.
2. Phosphors of 4 μm or less are 0.2 mg / cm ² or more, and 3.
A fluorescent film for a field emission display, which is applied at an application amount of 0 mg / cm ² or less. 2. The fluorescent film contains Ag in an amount of 300 with respect to a matrix.
Zn contained in the range of 1 ppm or more and 1500 ppm or less
S: Ag, X (where X is Al, at least one of halogen elements) phosphor, or Cu with 200p to the host
Zn contained in the range of pm or more and 1500 ppm or less
S: Cu, X (where X is Al, at least one of halogen elements) phosphor, or Au to the base material at 200 pp
ZnS contained in the range of m to 1500 ppm:
Au, X phosphor or Cu 200ppm or more 150
0ppm or less and Au 100ppm or more 600p
ZnS: Cu, Au, X phosphor containing pm or less, or Y ₂ O ₂ S: Eu phosphor, Y ₂ O ₃ : Eu phosphor containing Eu in an amount of 1% or more and 10% or less with respect to the matrix. The phosphor film for a field emission display according to claim 1, wherein at least one phosphor selected from the above is applied.