JPH01225040A - Electron emitting electrode and display device - Google Patents

Abstract

PURPOSE:To obtain a display device for a large screen with the excellent voltage and current characteristics by providing fine grains covered with an electron emitting material on the surface on the electron emission surface of an electron emitting electrode. CONSTITUTION:This device is constituted of a substrate 1, a cathode wiring 2, a load resistor 3, a cathode holding layer 4, fine grains 5, bulkhead plates 6, an anode 7, a faceplate 8 and phosphors 9. For the portion on the substrate side of this device, a cathode holding layer 4 made of conducting paste is formed by the silk screen printing method, for example, on the substrate 1 formed with the cathode wiring, fine grains 5 forming a thin film made of an electron emitting material such as LaB6 are pressed by pressure on it, it is then baked in the inert gas. A display device for a large screen with the excellent voltage and current characteristics is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron-emitting electrode and a display device using the same, and particularly to a gas discharge display device and an electron-emitting electrode used therein.

[Conventional technology]

In recent years, there has been a strong desire for display devices such as televisions to have larger screens and be thinner. A gas discharge display device is a promising display device that meets this demand. There are many types of gas discharge display devices, but all basically perform display by applying a voltage between a cold cathode and an anode to cause the cold cathode to emit electrons to generate gas discharge. Therefore, a cold cathode for a gas discharge display needs to be capable of emitting electrons at a low voltage.

Furthermore, since the cold cathode is consumed by collision with gas discharge septum ions, it is necessary for the cold cathode to have high wear resistance in order to extend the life of the gas discharge display.

Hitherto, hexaborides of lanthanum group metals such as LaB have been known as high-performance cathode materials that can emit electrons at low voltage and have high wear resistance. It has also been proposed to use it as a cold cathode. This cold cathode such as LaB5 was formed on the substrate of the gas discharge display device by thick film printing using a paste containing LaB6 particles, or by direct electron beam evaporation, plasma spraying, etc. (IEEJ technical report (II)
Part No. 147, pp. 66-81 (1981)).

[Problem to be solved by the invention]

The above-mentioned conventional technology does not give consideration to a cathode that has excellent voltage-current characteristics and is suitable for a large-screen display device, and a display device using such a cathode. That is, in the cathode formed by the thick film printing method, the surface of the La86 particles is inevitably contaminated with the firing residue of the organic binder, which causes a problem in that the voltage-current characteristics deteriorate.

In addition, cathodes formed by electron beam evaporation exhibit excellent voltage-current characteristics, but processing large substrates requires large evaporation equipment, which makes it difficult to increase the screen size of display devices. There was a problem.

Furthermore, the cathode formed by plasma spraying method is
There is a problem in that distortion occurs locally during plasma spraying, and therefore, it is difficult to enlarge the screen of the display device in this case as well.

An object of the present invention is to provide an electron-emitting electrode that has excellent voltage-current characteristics and allows the screen of a display device to be enlarged, and a display device using the same.

[Means to solve the problem]

The above object is an electron-emitting electrode or an electron-emitting electrode characterized in that the electron-emitting surface of the electron-emitting electrode has fine particles whose surface is coated with an electron-emitting material. In a display device in which a cathode consisting of an IiJ'll electrode and an anode facing the cathode are provided in a matrix shape, and a discharge gas is provided between them, the electron-emitting electrode is This is achieved by a display device characterized by having fine particles on its surface coated with an electron-emitting material.

Examples of the above-mentioned fine particles include fine particles of nickel and other metals, glassy carbon fine particles, AQ20. Fine particles of ceramics, etc. can be used.

Further, although the particles do not have to be electrically conductive, electrically conductive fine particles are preferable in order to establish electrical conduction with the cathode.

The size of the fine particles is preferably about 0.1 to 0.01+ nm. Further, it is preferable that the particle size distribution is narrow and the particle size is uniform.

The electron-emitting material is preferably coated to a thickness of about 1 cape to 20 capes. If the thickness is less than 1//IN, the life as an electrode will be short, and if the thickness exceeds 20#ff+, it will easily peel off from the fine particles. The electron-emitting material does not necessarily need to be applied to the fine particles to a uniform thickness. For example, when using a non-conductive electron-emitting material such as an oxide, it is preferable to apply this material to the conductive particles in patches.

If the electron-emitting material is conductive, the surface of the fine particles may be coated with a substantially uniform thickness. This kind of coating method is
For example, the sample stage in an electron beam evaporation apparatus is made rotatable, and a direction plate for particle movement is placed on the sample stage.

This can be carried out by a method such as providing a so-called baffle plate and performing electron beam evaporation while stirring the particles.

As the electron emitting material, for example, a hexaboride represented by the general formula MB6 (where M represents a lanthanum group metal), other metal hexaborides, etc. are used. For example, La
B,, Y BG, CeB,.

5cBG, BaB6, or a composite boride thereof. Metal oxides such as Bad, Cs2O, MgO, and SrO can also be used. In this case, it is preferable to mix a conductive material or to provide electronic conductivity. Further, it is also possible to use conductive fine particles and reduce the thickness of the electron-emitting material to reduce its electrical resistance, or to apply the electron-emitting material to the fine particles in spots as described above.

The display device of the present invention is a known gas discharge display device, that is, a cathode consisting of an electron-emitting electrode and an anode facing the cathode are provided in a matrix, and the above-mentioned fine particles are used as the cathode of the display device having a discharge gas between them. It is sufficient to use a cathode having an electron emitting surface.

As gas discharge display devices, for example, there are devices in which a phosphor is placed on a partition plate and the phosphor is made to emit light by a discharge gas, and there is also a device in which a discharge gas such as Ne or the like itself is made to emit light. It can also be applied to things like

[For production]

The operation of the present invention will be explained using FIG. FIG. 1 is a schematic cross-sectional view of an example of a gas discharge display device using a cold cathode of the present invention, in which 1 is a substrate, 2 is a cathode wiring, 3 is a load resistor, 4 is a cathode holding layer, 5 is fine particles, 6 7 is a partition plate, 7 is an anode, 8 is a face plate, and 9 is a phosphor. In the substrate side part of such a device, a cathode holding layer of conductive paste 1 is formed on the substrate on which @ electrode wiring is formed, for example by silk screen printing, and an electron emitting layer such as LaB is placed on top of the cathode holding layer. It can be created by compressing fine particles on which a thin film of a reactive material has been formed, and then firing them in an inert gas. The silk screen printing method used here can be used even on an area of 1 mm angle, and it is easy to press the fine particles onto that area. Further, since the fixation of the fine particles 5 is also carried out by heat-treating the entire substrate group in an inert gas, there is no need to use a vacuum device and no distortion occurs.

〔Example〕

Hereinafter, the present invention will be explained by giving examples.

Example 1 Using an electron beam evaporation apparatus, a LaB6 thin film was deposited to a thickness of 3/7 m on the surface of spherical nickel particles with a diameter of 0.05 m+ under the conditions of a vacuum degree of IU"nnI (g) and a film growth rate of 10 persons/sec. In this electron beam evaporation apparatus, as shown in the principle in FIG. The nickel particles move irregularly as they hit the direction plate 23. As a result, the surface of the nickel particles is almost uniformly aligned with the direction plate 23.
Covered by aBG.

Using this fine particle precooling@pole, the first
A dregs discharge display device with the structure shown in the figure was created. That is, gold paste was printed by screen printing on a soda lime glass plate that would serve as a face plate, and fired in the atmosphere (firing temperature 620°C).
℃) to form a gold wiring that will become an anode. In addition, a phosphor was applied to the inner wall of the soda-lime glass partition plate by a spray method using trichlorethylene as a dispersant. Gold wiring for the cathode was then created on soda lime glass as a substrate in the same manner as above, and then a resistive paste was screen printed on the gold wiring at a predetermined position and fired in the air (firing temperature 610°C). Then, a nickel paste film was formed as a cathode holding film on the load resistor using a screen printing method, and a particulate cold cathode was bonded onto the nickel paste film using a gas flow blowing method. It was fired in After that, the substrate on which the cold cathode, load resistor, and cathode wiring were formed, the partition plate coated with phosphor, and the face plate on which anode wiring was formed were glued together with low melting point glass (use temperature 470°C), evacuated, and Xe was sealed. did.

The dimensions of each part of the gas discharge display device manufactured by the above method are as follows: the pitch of the discharge cells is 1.0 Im+ both vertically and horizontally, the size of the cathode is 0.8 mm square, the size of the nickel film is 0.
8 nun square, thickness is 0.01mm, width of gold wiring is 0.
2+m+, the cathode-anode distance is 3, Onn,
The value of the load resistance is 1.7MΩ, and the number of discharge cells is 80 x
There were 60 pieces.

On the other hand, as a comparative example, after creating a cathode wiring and a load resistor on a substrate by the same method as above, LaB6 was formed on the load resistor by electron beam evaporation method, and then fluorescent A gas discharge display device was manufactured by gluing together the partition plate coated with the film and the face plate coated with the anode wiring. 1. The vapor deposition conditions for a B are a vacuum degree of 10-'
mm1 (, the film growth rate is 10 people/second, the thickness of the created LaB film is 3 μm, the size is 0.8 nu square, and the dimensions of other parts of the gas discharge display device are as described in the present invention) It was made the same as that of .

The voltage/current characteristics of a gas discharge display device using the LaB6-coated fine particles of the present invention as a cold cathode and a comparative example gas discharge display device using a LaB6 thin film formed on a substrate as a cold cathode are shown by straight line 31 in FIG. It became like 32. As seen in the figure, the current value of the voltage-current characteristics of the display device of the present invention is
Although it is slightly lower than that of the comparative example, in practical terms, the same effect can be obtained by increasing the voltage only slightly, and in practical terms it can be said that the characteristics are almost the same. Therefore, the effect of reducing production costs is significant. Further, the gas discharge display device of the present invention has a 4000
It was confirmed that the voltage-current characteristics did not change even if the time display was continued, and the life characteristics were good.

Example 2 LaB was applied to the surface using the same method and equipment as in Example 1.

We created microparticles that formed a thin film. Then, using these fine particles and using the same method as in Example 1, the number of discharge cells was 400
Three hundred gas discharge display devices were created.

When the voltage-current characteristics of this gas discharge display device were measured, they were consistent with the 80 x 60 cell gas discharge display device of Example 1, and even if the number of discharge cells was increased, that is, the screen was made larger, the voltage - It was confirmed that the current characteristics did not change.

The size of the display device created in this example is 600x500.
mn, and in order to create a LaB6 thin film on a substrate of this size, an apparatus with a vacuum chamber larger than this size is required. In contrast, in the present invention, the vacuum chamber of the electron beam evaporation apparatus used may be small.

Example 3 A LaB6 thin film having a thickness of 6 layers was formed on the surface of the same spherical nickel particles as in Example 1 by high frequency sputtering deposition. The high frequency power during vapor deposition was LOW/cJ, and the film growth rate was 2.
Corridor/Tokitoshi. Using this cold cathode, a gas discharge display device having the same number of discharge cells as in Example 2 (400×300) was fabricated.

The voltage-current characteristics of this gas discharge display device were as shown by the straight line 41 in FIG. This result shows practically the same effect as the voltage-current characteristic line 42 of the LaBG thin film cold cathode produced by the electron beam evaporation method of Example 1. From this, it is possible to apply L on the surface by high-frequency sputtering deposition method.
It can be seen that the gas discharge display device in which the fine particles on which the aB thin film is formed is used as a cold cathode has the same characteristics as the gas discharge display device in which the LaB6 thin film is formed on the substrate.

Example 4 A BaB thin film with a thickness of 6 mm was formed on the surface of the same granular nickel particles as in Example 1 by high-frequency sputtering deposition. Then, using this cold cathode, a gas discharge display device having the same number of discharge cells (80×60) as in Example 1 was created.

On the other hand, as a comparative example, a cathode wiring and a load resistor were formed on a substrate in the same manner as the LaB thin film cold cathode of Example 1, and then a BaBG thin film was formed thereon by high frequency sputtering. Then, a gas discharge display device having 80×60 discharge cells was produced.

The voltage-current characteristics of a display device using fine particles formed with the BaB6 thin film of the present invention as a cold cathode and a display device using the BaB6 thin film itself as a cold cathode are as shown by straight lines 51 and 52 in FIG. It showed the same effect.

From this, it can be seen that a gas discharge display device in which fine particles formed with a BaB6 thin film are used as a cold cathode has characteristics equivalent to a gas discharge display device in which a BaBG thin film is formed on a substrate.

In the above examples, spherical nickel particles were used as the raw material fine particles, and L a B ; and BaB;
, examples have been described in which electron beam evaporation, high-frequency sputtering evaporation, and pressure bonding are used as a method for coating fine particles and a pressure bonding method as a method for supporting fine particles on a holding layer, but the present invention is limited by these materials and processes. It's not a thing.

For example, other metal particles, glassy carbon particles, An20. Particles etc. may also be used. The shape of the fine particles is preferably spherical because it is easy to form a uniform thin film and it is easy to support the fine particles on the holding layer by pressure bonding or the like. In addition, the size of the fine particles is adjusted so that the particles do not become embedded in the retention layer.
It is desirable that the thickness be greater than the thickness of the retaining layer.

Plasma spraying, ion blasting, and the like can also be used as a coating method for fine particles. The fine particles may be supported on the holding layer by blowing with a gas stream.

Furthermore, the display device does not have a phosphor, but may be one in which the discharge gas itself emits light, such as neon.

Note that if a cathode is made using the same method as in the present invention using fine particles of a high-performance cathode such as LaB,
Since the shape of these fine particles is complicated, there is a problem that the support on the retention layer becomes non-uniform.

Furthermore, since the shape is complicated, when used as a cathode, electron emission becomes non-uniform and the performance becomes unstable.

〔Effect of the invention〕

According to the present invention, a gas discharge display device with excellent voltage and current characteristics and a large screen can be manufactured using a small device. Therefore, reduction in manufacturing cost and improvement in reliability can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an example of a gas discharge display device showing the principle of the present invention, Fig. 2 is a schematic diagram of a sample stage of an electron beam evaporation device used in the present invention, and Figs. A diagram showing the voltage and current characteristics of a gas discharge display device using the formed fine particles as a cathode. FIG. 5 is a diagram showing voltage and current characteristics of a gas discharge display device using the formed fine particles as a cathode. . 1... Substrate 2... Cathode wiring 3... Load resistance 4... Cathode holding layer 5... Fine particles
6... Partition plate 7... Anode 8 - Face plate 9... Phosphor 21 Nickel particles 22
- Rotating table 23...Particle movement direction plate 31
．． 41.51・Characteristics of the present invention 32.42.52・Characteristics of comparative example

Claims (1)

[Scope of Claims] 1. An electron-emitting electrode comprising, on an electron-emitting surface of the electron-emitting electrode, fine particles whose surface is coated with an electron-emitting material. 2. The above electron-emitting material has the general formula MB_6 (here M
The electron-emitting electrode according to claim 1, which is a material represented by lanthanum group metal. 3. The electron-emitting electrode according to claim 1, wherein the electron-emitting material is formed as a coating layer on the surface of the fine particles by sputtering deposition, electron beam vacuum deposition, or plasma spraying. 4. In a display device in which a cathode consisting of an electron-emitting electrode and an anode facing the cathode are arranged in a matrix, and a discharge gas is provided therebetween, the electron-emitting electrode has an electron-emitting material on its electron-emitting surface. A display device characterized by having a surface coated with fine particles. 5. The above electron-emitting material has the general formula MB_6 (herein M
5. The display device according to claim 4, wherein the display device is made of a material represented by a metal of the lanthanum group.