JP2000215832A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent field emission cathodes from adsorbing gas molecules and to prolong the life by providing phosphors luminescing when receiving irradiation of electrons emitted from the field emission cathodes and a vacuum maintaining getter, and arranging the phosphors and the getter face to face at the prescribed interval. SOLUTION: Electrons emitted from field emission cathodes 3 move toward a second substrate 2. When a proper potential is applied to a getter film 6, the electrons move toward a first substrate 1 with their orbits bent. The electrons are accelerated and enter phosphor films 4 to excite phosphors to luminesce. When the electrons enter the phosphor films 4, gas molecules of hydrogen and H2O are emitted from the phosphors. The gas molecules enter the getter film 6 of the second substrate 2 and are adsorbed without being floated in the vacuum space between the first substrate 1 and the second substrate 2. The emission current of the electrons from the field emission cathodes 3 is not reduced, and a stable display with no luminance deterioration can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device using a field emission cathode.

[0002]

2. Description of the Related Art In recent years, as a thin display device using a minute field emission cathode, an FED (Field Emission Display) has been developed.
R & D is active. FIG. 10 shows a configuration diagram of a conventional FED. The minute field emission cathode includes a sharp conical emitter tip 101, a gate electrode line (gate feed line) 103 for extracting electrons, and an emitter electrode line (emitter feed line) for applying a negative voltage to the emitter tip.
102 and an insulating layer 104 separating the gate electrode line and the emitter electrode line from each other as shown in FIG.
The entire substrate including the glass substrate is referred to as a cathode plate 109. On the other hand, the anode plate 107 has R, G, B
Phosphor film 108 is formed.

The emitter electrode line 102 and the gate electrode line 103 are arranged so as to intersect with each other, and hundreds to thousands of emitter tips are formed at intersections on the emitter electrode line. The display tip (for example, pixel) 106 is formed by the emitter tips of several hundreds.
Is configured.

[0004] A cathode plate 109 on which a field emission cathode is formed and an anode plate 107 on which a phosphor layer 108 is formed are opposed to each other with a certain gap therebetween, and the inside thereof is sealed with a vacuum, thereby forming a vacuum container. Is done. A voltage is applied to a matrix wiring composed of an emitter electrode line and a gate electrode line to extract electrons from the field emission cathode, and the voltage applied between the cathode plate 109 and the anode plate 107 accelerates the electrons to form a phosphor layer 108. Irradiate to excite the phosphor to emit light. When this excitation light emission occurs, gas molecules such as oxygen are emitted from the phosphor 108.

[0005]

Electron beam irradiation in a vacuum is generally used as a means for degassing a sample. In the conventional FED, gas molecules emitted from the phosphor when electrons enter the phosphor are formed on the cathode plate 1.
Through a slight gap between the anode electrode 107 and the anode plate 107, it was adsorbed by the getter provided around the display area. Since the electron beam emitted from the field emission cathode spreads and spreads, the gap between the cathode plate 109 and the anode plate 107 cannot be made large in order to obtain a high-definition display device. It is limited to about 2 mm.

On the other hand, the inside of the panel before emitting electrons is 10
Since it is sealed in a vacuum of about ^-7 Torr, the mean free path of gas molecules in the panel is about 500 m. This is much larger than the gap between the two substrates. Therefore, the gas molecules emitted from the phosphor 108 travel straight without colliding with each other, reach the opposing cathode plate 109, and are adsorbed. The gas molecules adsorbed on the cathode plate 109 are released again into the panel by ion bombardment and the like, and go straight to the anode plate 1.
07 is reached. While repeating such a behavior, only the molecules that have reached the getter are adsorbed on the getter. That is, the gas molecules released from the phosphor 108 always adsorb to the cathode plate 109 before being adsorbed to the getter. Some of these gas molecules adsorb to the field emission cathode.

In general, it is known that, when gas molecules are adsorbed on the surface of a field emission cathode, the work function increases and the emission current decreases. When the field emission cathode is applied to a display device, the brightness decreases as the emission current decreases. FIG.
In the structure of the conventional FED shown in (1), it is inevitable that gas molecules are adsorbed to the field emission cathode, and therefore, it is very difficult to maintain the vacuum in the vacuum vessel and secure the reliability of the display device. The present invention has been made in view of the above circumstances, and has as its object to provide a long-life display device in which gas molecules are not adsorbed to a field emission cathode.

[0008]

According to the present invention, there is provided a field emission cathode which emits electrons by applying an electric field into a vacuum vessel, a phosphor which emits light upon irradiation of electrons emitted from the field emission cathode, With getter for maintaining vacuum,
It is an object of the present invention to provide a display device, wherein the phosphor and the getter are formed so as to face each other while maintaining a predetermined interval. Here, the field emission cathode and the phosphor are formed on the same surface of a first substrate, the getter is formed on a second substrate, and the surface of the first substrate on which the phosphor is formed and the getter are formed. The surfaces of the second substrate may be opposed to each other. According to the present invention, the gas molecules emitted from the phosphor are adsorbed by the getter and do not adhere to the field emission cathode, so that high brightness,
A long-life display device can be provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A field emission cathode according to the present invention mainly comprises a conical emitter tip, an emitter electrode line for supplying a negative voltage to the emitter tip, and a gate electrode line for accelerating electrons. The emitter electrode line and the gate electrode line are formed in a matrix, and a region where both lines intersect is a pixel, and a large number of emitter tips are arranged in this pixel region. The getter for maintaining the vacuum is formed of a material that adsorbs gas molecules emitted from a phosphor or the like, and an evaporable or non-evaporable getter is used.
A barium film is used. Further, a predetermined negative potential may be applied to the getter in order to repel electrons emitted from the field emission cathode.

Further, a predetermined groove or projection may be formed between the field emission cathode and the phosphor. At this time, the groove or the protrusion may have any size and shape that can increase the creeping distance between the field emission cathode and the phosphor, and the size and shape are not particularly limited. Further, in the present invention, an emitter electrode line for applying a negative voltage to the field emission cathode, and a gate electrode line patterned in a cross-shape with the emitter electrode line are formed on the first substrate, A comb-shaped comb portion of the gate electrode line is formed in a region including the field emission cathode, which is an intersection region between the gate electrode line and the emitter electrode line,
Further, the phosphor may be formed on the first substrate at a position different from the emitter electrode line and the gate electrode line. Here, the phosphors of the same color may be arranged on both sides of the comb-shaped comb portion, or may be arranged so as to surround the comb-shaped portion.

In the present invention, the phosphor is formed on a first substrate, the getter is formed on a second substrate, the field emission cathode is formed on a third substrate, and the third substrate is formed on the third substrate. The phosphor and the field emission cathode are arranged between the first substrate and the second substrate constituting a vacuum vessel and so as to be kept at a predetermined distance from the first substrate and the second substrate. May be formed on the surfaces of the third substrate and the first substrate, respectively, so as to face the getter. Here, the third substrate is maintained at a predetermined distance from the first substrate and the second substrate by a spacer, and the spacer has a lattice shape or a parallel linear shape formed so as to divide a pixel region. You may comprise.

Further, on the third substrate, an emitter electrode line for applying a negative voltage to the field emission cathode, and a gate electrode line which is crossed with the emitter electrode line and is patterned in a shape of a cross are formed. A comb-shaped comb-shaped portion of the electrode line is formed in a region where the gate electrode line and the emitter electrode line intersect with each other and includes a field emission cathode. A through hole penetrating the direction may be formed, and the phosphor may be formed on the first substrate at a position facing the through hole. Here, the getter may be further formed on a surface of the third substrate on which the field emission cathode is not formed.

[0013] Further, according to the present invention, the phosphor is formed on a first substrate, the getter is formed on a second substrate facing the first substrate, and the field emission cathode is formed of the phosphor and the getter. Is formed on a third substrate disposed at a position different from the facing region, and is configured to emit electrons into a space formed by the phosphor and the getter. To provide.

Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. Note that the present invention is not limited to this. FIG. 1 is a sectional view showing one embodiment of a display device using the field emission cathode of the present invention. In FIG. 1, a display device of the present invention mainly includes two substrates 1 and 2.
And 2. On a first substrate 1 made of a transparent material such as glass, a field emission cathode 3, a transparent conductive film 5 for applying a positive voltage, and a phosphor film 4 are formed. The field emission cathode 3 is a matrix element in which an emitter tip is arranged in an intersection region between an emitter electrode line and a gate electrode line, as in the related art. The opposing second substrate 2 includes
A thin getter film 6 is formed on one surface.

When an appropriate potential is applied to the emitter electrode line and the gate electrode line, respectively, as in the prior art, electrons are emitted from the field emission cathode 3 and the electrons travel toward the second substrate 2. For example, a voltage of −40 V is applied to the emitter electrode line and a voltage of +40 V is applied to the gate electrode line.

When an appropriate potential (for example, -40 V) is applied to the getter film 6, the electrons are repelled before the getter film 6, and the orbit is bent and proceeds toward the first substrate 1 (see FIG. 1). 1 orbit 7). The transparent conductive film 5 below the phosphor film 4 has a positive potential (+2
00V). Thereby, the electrons are accelerated and enter the phosphor film 4 to excite the phosphor to emit light. The user sees the light excited by the phosphor from below the first substrate as shown in FIG.

In FIG. 1, when electrons enter the phosphor film 4, gas molecules such as oxygen and H ₂ O are emitted from the phosphor. The gas molecules travel straight upward in FIG.
And is absorbed by the getter film 6. Therefore, since the gas molecules do not float in the vacuum space between the first substrate and the second substrate and do not adhere to the field emission cathode 3, the emission current of electrons from the field emission cathode 3 does not decrease. A stable display without luminance degradation can be obtained. That is, a display device with high luminance and long life can be provided.

Further, in order to improve the withstand voltage characteristics of the display device, the following grooves and projections may be provided on the surface of the first substrate. FIG. 2 shows a sectional view of an embodiment of a display device in which a groove 11 is provided between the phosphor film 4 and the field emission cathode 3 on the first substrate 1. The width of the groove 11 in the left-right direction may be about 10 μm, and the depth may be about 100 μm. FIG. 3 shows a projection 12 between the phosphor film 4 and the field emission cathode 3 on the first substrate 1.
1 shows a cross-sectional view of an embodiment of a display device provided with. The width of the protrusion 12 may be about 10 μm, and the height may be about 100 μm. The grooves in FIG. 2 and the protrusions in FIG. 3 can be formed by processing the substrate by a sandblast method.

Thus, the groove 11 as shown in FIG. 2 or the protrusion 1 as shown in FIG. 3 is provided between the field emission cathode 3 and the phosphor film 4.
When 2 is provided, the creepage distance between the field emission cathode 3 and the phosphor film 4 is increased, so that the withstand voltage is improved about 5 times as compared with the case where no groove or projection is provided. Therefore, 1
A high voltage of kV or more can be applied. As the applied voltage is increased, the luminous efficiency of the phosphor is improved, and the metal film can be used for the phosphor film, so that the luminance is increased and a bright display device can be obtained.

FIG. 4 is a plan view of the first substrate of the display device of the present invention shown in FIG. 1 as viewed from above. The emitter electrode line 21 extends in the vertical direction in FIG. 4, and the gate electrode line 22 extends in the horizontal direction. The gate electrode lines 22 are patterned in a comb shape, and the field emission cathodes 3 are formed in the comb teeth 23.

In the case of a color display device, phosphor films 4 of the same color are formed on both left and right sides of the field emission cathode 3. B in the figure
Indicates a region where a blue phosphor film is formed, R indicates a region where a red phosphor film is formed, and G indicates a region where a green phosphor film is formed. The electrons emitted from the field emission cathode 3 take a trajectory indicated by reference numeral 7 in FIG. 1 and enter the left and right phosphor films 4.
In addition, as shown in FIG. 5, the phosphor film 4 may be formed so as to surround the comb teeth 23 on which the field emission cathodes 3 are formed.

Reference numerals 41 and 42 in FIG. 5 indicate phosphor films of different colors. The length of each part shown in FIG. 5 can be constituted by the following numerical values, for example. a1 = 300μ
m, a2 = 220 μm, a3 = 50 μm, a4 = 10 μ
m, a5 = 10 μm, a6 = 100 μm, a7 = 30 μ
m, a8 = 30 μm and a9 = 190 μm. The phosphor film 41 of one color forms an area of 300 μm in length and 100 μm in width. Such red R, blue B and green G
Are combined into one set to form one pixel. Therefore, in this case, one pixel is 300 μm × 30
It occupies an area of 0 μm.

Further, as shown in FIG. 4, in order to support the atmospheric pressure applied to the first substrate 1 and the second substrate 2, the spacer 24 is formed in a parallel linear shape. Further, in order to prevent electrons from flowing into adjacent pixels, the spacers 24 may have a lattice shape extending vertically and horizontally. In the panel structure of the conventional display device, a columnar spacer was used in order to secure the exhaust conductance. However, in the configuration according to the present invention, the exhaust conductance can be sufficiently secured.
Parallel linear or lattice shaped spacers can be used. That is, it is easier to form a spacer having a higher aspect ratio than a columnar shape. In the case of forming lattice-shaped spacers, parallel-linear spacers may be formed on the first substrate and the second substrate, respectively, in directions orthogonal to each other, and then bonded together.

FIG. 6 is a sectional view of an embodiment of the display device of the present invention having a three-substrate configuration. Here, the phosphor film 4 is the first
The field emission cathode 3 is formed on the intermediate substrate 33, and the getter film 6 is formed on the second substrate 32, respectively. Further, the intermediate substrate 33 is provided with a through hole 34 serving as an electron passage. The through holes 34 are provided on both sides of the field emission cathode 3, and the first substrate 3
The phosphor film 4 formed on 1 is arranged just below the through hole 34. Further, the through-hole 34 may be provided at the position of the phosphor film 4 shown in FIG. Therefore, the plan view of the display device of FIG. 6 is substantially the same as that of FIG.

The intermediate substrate 33 is provided with an emitter electrode line and a gate electrode line in the same manner as described with reference to FIG. 4, and appropriate negative electrodes and positive potentials are respectively applied. Similarly, an appropriate negative potential is applied to the getter film 6. Electrons emitted from the field emission cathode 3 are repelled by the potential of the getter film 6 and enter the phosphor film 4 through the through holes 34.

The first substrate 31 and the intermediate substrate 33 are bonded via the spacer 36 such that the through hole 34 is located right above the phosphor film 4. In the structure of FIG. 6, since the creepage distance between the field emission cathode 3 and the phosphor film 4 is longer than that of the conventional structure, it is not necessary to form the spacer 36 having a high aspect ratio. Accordingly, also in FIG. 6, a spacer 36 having a parallel linear shape or a lattice shape, which can be easily formed, may be used. As the getter film 6, a thin plate non-evaporable getter is used. The getter film 6 is attached to one entire surface of the second substrate. In FIG. 6, a spacer 35 having a parallel linear shape or a lattice shape is provided between the second substrate 32 and the intermediate substrate 33.

When a display device is constructed by using these substrates, first, the intermediate substrate 33 and the first substrate 31 are aligned and bonded via the spacer 36 as described above, and then this is The second substrate 32 to which the film 6 is attached is bonded via a spacer 35. Furthermore, it heats in a vacuum at 450 degreeC for 10 minutes, softens a frit seal, and seals it. At this time, the getter film 6 is also heated at the same time, so that the getter film 6 is activated and starts to adsorb gas molecules.

Alternatively, the getter film 6 may be of an evaporation type. In this case, the evaporable getter is activated toward the second substrate 32 in a vacuum to form a barium film. And this is the first in vacuum
What is necessary is just to adhere | attach and seal the structure of the board | substrate 31 and the intermediate board | substrate 33. In the configuration of FIG. 6 as well, gas molecules do not adsorb to the field emission cathode, so that a display device with high luminance and long life can be provided. The getter film 6 may be provided on the surface of the intermediate substrate 33 where the field emission cathode 3 is not formed (in FIG. 6, the lower surface of the intermediate substrate 33). According to this configuration, a display device with higher luminance and longer life can be provided.

FIG. 7 is a cross-sectional view of a display device according to an embodiment in which the field emission electrode 3 is formed outside a region where the phosphor film 4 and the getter film 6 face each other. The display device having this structure can also be used as a planar light source such as a backlight of a liquid crystal display. In FIG. 7, a first substrate 71 on which the phosphor layer 4 is formed and a second substrate 72 on which the getter film 6 is formed are arranged to face each other. The first substrate 71 and the second substrate 72
May be the same as that shown in FIG.

The third substrate 73 on which the field emission cathode 3 is formed is located between the first substrate 71 and the second substrate 72,
It is provided at a position outside the space formed by the opposing phosphor film 4 and getter film 6. Here, the field emission cathode 3
Is formed on one surface of the third substrate 73 so that electrons emitted from the emitter tip are emitted into a space formed by the phosphor film 4 and the getter film 6.
The third substrate 73 also serves as a spacer, and its material may be glass as in the first substrate. In addition, also in the case of FIG. 7, the user views the display from the first substrate side.

FIG. 8 is a perspective view of the display device shown in FIG. 7, and FIG. 9 is a sectional view thereof. A plurality of third substrates 73 on which the field emission regions are formed are arranged in parallel straight lines.
Further, the third substrates 73 may be arranged at a distance of 2 mm (a16) when the thickness (a15) is 50 μm, the height (a13) is 200 μm, and the screen size is 5 inches diagonally. Further, when the thickness (a12) of the first substrate is about 0.5 mm and the thickness (a14) of the second substrate is about 0.5 mm, the thickness of the entire display device can be about 1.2 mm. This is about ４ of the thickness of a conventionally used backlight for high luminance.

Also, as in the case of the embodiment of FIG. 1 and the like, gas molecules emitted from the phosphor film hardly adsorb to the field emission cathode, so that the display device of FIG. 7 is used as a light source. Can realize a high-performance light source having a lifetime of 10,000 hours or more. Therefore, according to the configuration as shown in FIG. 7, a thin, high-brightness, long-life light source can be realized.

[0033]

According to the present invention, gas molecules emitted from the phosphor by irradiation of electrons from the field emission region travel straight and enter the getter film and are adsorbed. Therefore, since gas molecules do not reach the field emission cathode, the emission current does not decrease, and a stable display without luminance degradation can be obtained. Further, a groove or a projection is provided between the phosphor film and the field emission cathode, or the field emission cathode is arranged on the intermediate substrate, and the substrate on which the phosphor film and the getter film are arranged is vertically opposed. With this configuration, the creepage distance between the field emission cathode and the phosphor film is increased, so that the withstand voltage between the phosphor film and the field emission cathode is increased, and the life is further extended. As a result, high-luminance display is possible without increasing the aspect ratio of the spacer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of a display device using a field emission cathode of the present invention.

FIG. 2 is a sectional view of an embodiment in which a groove is provided on a first substrate in the display device of the present invention.

FIG. 3 is a cross-sectional view of an embodiment in which a projection is provided on a first substrate in the display device of the present invention.

FIG. 4 is a plan view of the display device shown in FIG. 1 in the present invention.

FIG. 5 is a plan view of a display device having a phosphor film in a shape surrounding a field emission cathode in the present invention.

FIG. 6 is a sectional view of an embodiment of a display device having a three-substrate configuration according to the present invention.

FIG. 7 is a cross-sectional view of a display device in which a field emission cathode is formed outside a region where a phosphor film and a getter film face each other in the present invention.

8 is a perspective view of the display device shown in FIG.

9 is a cross-sectional view of the display device shown in FIG.

FIG. 10 is a configuration diagram of a conventional FED.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 2nd board | substrate 3 Field emission cathode 4 Phosphor film 5 Transparent conductive film 6 Getter film 7 Electron orbit 11 Groove 12 Projection 21 Emitter electrode line 22 Gate electrode line 23 Comb part 24 Spacer 31 First substrate 32 Second substrate 33 Intermediate substrate 34 Through hole 35 Spacer 36 Spacer 71 First substrate 72 Second substrate 73 Third substrate 74 Frit seal

Claims (11)

[Claims] 1. A field emission cathode, which emits electrons by applying an electric field to a vacuum vessel, a phosphor which emits light by receiving irradiation of electrons emitted from the field emission cathode, and a getter for maintaining a vacuum. Wherein the phosphor and the getter are formed so as to face each other while maintaining a predetermined interval. 2. The method according to claim 1, wherein the field emission cathode and the phosphor are formed on the same surface of a first substrate forming a vacuum container, and the getter is formed on a second substrate forming a vacuum container. The display device according to claim 1, wherein: 3. The semiconductor device according to claim 2, wherein a groove or a protrusion having a predetermined size is formed on the surface of the first substrate and between the field emission cathode and the phosphor. Display device. 4. An emitter electrode line for applying a negative voltage to the field emission cathode, and a gate electrode line crossed with the emitter electrode line and patterned in a cross-shape on the first substrate; A comb-shaped comb portion of the electrode line is formed in a region including the field emission cathode, which is an intersection region between the gate electrode line and the emitter electrode line, and the phosphor is different from the emitter electrode line and the gate electrode line. The display device according to claim 2, wherein the display device is formed at different positions. 5. The display device according to claim 4, wherein the phosphors of the same color among the phosphors are arranged on both sides of a comb-shaped comb portion of the gate electrode line. 6. The phosphor is formed on a first substrate, the getter is formed on a second substrate, the field emission cathode is formed on a third substrate, and the third substrate constitutes a vacuum container. The first substrate and the second substrate are disposed so as to be maintained at a predetermined distance from the first substrate and the second substrate, and the phosphor and the field emission cathode are disposed in the getter. 2. The display device according to claim 1, wherein the display device is formed on the surface of the third substrate and the surface of the first substrate, respectively, so as to face the substrate. 7. The method according to claim 1, wherein the third substrate is firstly provided by a spacer.
7. The display device according to claim 6, wherein a predetermined distance is maintained with respect to the substrate and the second substrate, and the spacer has a lattice shape or a parallel linear shape formed so as to divide a pixel region. 8. An emitter electrode line for applying a negative voltage to the field emission cathode, and a gate electrode line crossed with the emitter electrode line and patterned in a cross-shape on the third substrate; A comb-shaped comb-shaped portion of the electrode line is formed in a region where the gate electrode line and the emitter electrode line intersect and includes the field emission cathode, and a third portion is formed at a position different from the comb-shaped portion.
7. The display device according to claim 6, wherein a through-hole penetrating in a vertical direction of the substrate is formed, and the phosphor is formed on the first substrate at a position facing the through-hole. 9. The phosphor is divided into portions that emit red, blue, and green colors, respectively, and the spacer is formed in a grid shape or a parallel linear shape formed to isolate each of the divided regions. 9. The display device according to claim 8, wherein: 10. The display device according to claim 6, wherein the getter is further formed on a surface of the third substrate on which no field emission cathode is formed. 11. The phosphor is formed on a first substrate,
The getter is formed on a second substrate facing the first substrate, and the field emission cathode is on a third substrate located at a position different from a region where the phosphor and the getter face each other. The display device according to claim 1, wherein the display device is formed so as to emit electrons into a space formed by the phosphor and the getter.