JPH0494032A - Electron emission element and image forming device using electron emission element - Google Patents

Abstract

PURPOSE:To make the electron performance such as the electron emission amount and the electron emission efficiency controllable easily, and to obtain an electron emission element with little unevenness of performance between elements, by composing the part of difference in level of the element with a material whose heat conductivity is different from that of an insulating base, and positioning an electron emission member near the part of the difference in level of the element. CONSTITUTION:Between electrodes 33 and 34 on an insulating base 31, an electron emission regulating member 32 is provided projecting upward. The amount of the difference in level formed by the electron emission regulating member 32 is enough to be 0.1 to 1mum. And the width is enough to be 1/2 the interval of the electrodes. As the electron emission regulating member 32, a material whose thermal conductivity is different from that of the base 31. When a blue plate glass is used as the insulating base 31, for example, an insulating material such as alumina, or a metal material such as Au is used for the member 32. Then, by dispersing and spreading an organic metal between the electrodes and then baking it, a minute metallic particle membrane 35 is formed between the electrodes 33 and 34. By applying a current feeding process to the minute particle member 35, an electron emision member 36 is formed linearly along the part of the difference in level of the electron emission regulating member 32.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cold cathode type electron-emitting device and an image forming apparatus using the device.

[Prior Art] Conventionally, as an element that can emit electrons with a simple structure,
For example, MI Ellingson (M.

The cold cathode device announced by E. R., Elinson et al. [Radio Engineering Electron Physics (Radi.

Eng, Ele, ctron Phys,) 1st.
0, pp. 1290-1296, 1965.

This device utilizes the phenomenon in which electrons are emitted by passing a current parallel to a small-area thin film formed on a substrate, and is generally referred to as a surface conduction electron-emitting device. .

This surface conduction type electron-emitting device is based on the 5NO2 (Sb) thin film developed by Ellingson et al.
(G, Dittmer: “Th1n 5olid
Films”), Vol. 9, p. 317, (1972)], I
Using TO thin film [M. Hartwell and G.S.
Edie Hunfalen (M, Hartwe 11an)
d C, G, Fonstad;
ans, ED Conf,”) 519 pages.

(1975)], by carbon thin film [Hisashi Araki et al.: “Vacuum” Vol. 26, No. 1, p. 22.

(1983)] etc. have been reported.

A typical device configuration of these surface conduction type electron-emitting devices is shown in FIG. In the same figure, 1 and 2 are electrodes for obtaining electrical connection, 3 is a thin film formed of an electron-emitting material,
4 is a substrate, and 5 is an electron emitting part.

Conventionally, in these surface conduction type electron-emitting devices, an electron-emitting portion is formed in advance by an electrical heating process called forming before electron emission. That is, the electrode 1
By applying a voltage between the electrode 2 and the electrode 2, electricity is applied to the thin film 3, and the Joule heat generated thereby causes the thin film 3 to be locally destroyed, deformed, or altered in quality, resulting in electron emission in a state of high electrical resistance. By forming the portion 5, an electron-emitting material is obtained.

Note that an electrically high resistance state means that a part of the thin film 3 has a resistance of 0.
It refers to a discontinuous film that has a crack of 5 μm to 5 μm and has a so-called sea-island structure inside the crack. The sea-island structure generally refers to a film in which fine particles with a diameter of several tens to several μm are present on the substrate 4, and each fine particle is spatially discontinuous but electrically continuous.

Conventionally, a surface conduction type electron-emitting device is one in which a voltage is applied to the above-mentioned high-resistance discontinuous film through an electrode 1.2, and a current is caused to flow across the surface of the device, thereby causing the above-mentioned fine particles to emit electrons.

However, the above-mentioned conventional forming element using electrical heating has the following problems.

1) Because it is impossible to design a sea-island structure that will become an electron emitting region,
It is difficult to improve the elements, and variations between elements are likely to occur.

2) Because the Joule heat generated during the forming process is large, the base is easily destroyed and it is difficult to mulch.

3) A large current cannot be obtained because the material of the island is limited to gold, silver, SnO2, 'ITO, etc., and materials with a small work function cannot be used.

Due to the above-mentioned problems, surface conduction electron-emitting devices have not been actively applied in industry, despite having the advantage of a simple device structure.

As a result of studies in view of the above-mentioned problems, the present inventors proposed in Japanese Patent Application No. 63-1-7570 and Japanese Patent Application No. 63-11048 that by disposing a fine particle film between electrodes and subjecting it to energization treatment, We proposed a new surface conduction type electron-emitting device with an electron-emitting region. A block diagram of this new electron-emitting device is shown in FIG.

In the figure, 11 and 12 are electrodes, 13 is a particulate film,
14 is an electron emitting section, and 15 is a substrate.

The characteristics of this electron-emitting device include the following.

1) Since the electron emitting portion 14 can be formed by passing a very small current through the particulate film 13, an element without element deterioration can be formed, and furthermore, the shape of the electrode can be arbitrarily designed.

2) Since the fine particles that form the fine particle film themselves become constituent materials for electron emission, it is possible to design the material and shape of the fine particles.
Electron emission characteristics can be changed.

3) The selection of materials for the substrate 15 and electrodes, which are the constituent materials of the element, is expanded.

[Problems to be Solved by the Invention] However, in the surface conduction electron-emitting device previously proposed by the above inventors, the electron-emitting portion 14 is formed within the fine particle film 13 between the electrodes, as shown in FIG. , the electron emitting part 14 is the electron emitting position, but in reality, the electron emitting part 14 is formed from a fine range of 0.01 μm to 0.5 μm, and its position is in the fine particle film. Variations occur due to formation conditions, energization treatment conditions, etc.; it is difficult to accurately arrange them at predetermined positions between the electrodes.

In Fig. 2, the electron emitting part is drawn as a straight line, but in reality it meanderes considerably between the electrodes 11 and 12, and its shape changes considerably depending on the current supply conditions, so that the effective electron emitting part It was not possible to design a suitable length.

Generally, the distance between electrodes 11 and 12 is 0.5 μm to 50 μm
However, the wider the distance between the electrodes, the more difficult it was to control the position of electron emission.

Such variations in the position of the electron-emitting portion cause variations in the amount of electron emission when used for electron emission, and especially when used as a planar electron source in which a plurality of these elements are arranged, the electron emission may vary depending on the location. There was a problem with the amount changing.

As an effective application of planar electron sources, Japanese Patent Application Laid-Open No. 56-2344
A thin image forming device as described in Publication No. 5, in which a plurality of planar electron sources and phosphor targets each receiving electron beam irradiation from the electron sources are opposed to each other. However, when the above-mentioned surface conduction type electron-emitting device is applied as an electron source of this image forming apparatus, the amount of electron emission of each device is different, so the fluorescence brightness of the phosphor differs depending on the location, causing display unevenness.

In addition, in the conventional electron-emitting device that uses electrical heating as described above, the large power required for electrical heating causes significant deterioration of the electron-emitting part and substrate, making it impossible to control the electron-emitting characteristics and the position of the electron-emitting part. Met.

That is, an object of the present invention is to provide an electron-emitting device that solves the problems of the prior art as described above, and an image forming apparatus using the device.

[Means and effects for solving the problems] The features of the present invention, which has been achieved to solve the above problems, are as follows. In an electron-emitting device including a low-resistance portion made of electrically connected fine particles and a pair of electrodes for supplying current to the low-resistance portion, a step portion of the device has a thermal conductivity different from that of an insulating substrate. The electron emitting device is made of a material, and the electron emitting portion of the device is located near the step.

Second, image forming includes at least an electron source in which a plurality of the electron-emitting devices described in the first aspect are arranged in a vacuum container, and an image forming member that forms an image by irradiation with electrons emitted from the electron source. The point is that it is a device.

That is, the present invention solves the above-mentioned problems by providing a fine particle film or a thin film conductor containing fine particles between opposing electrodes, and providing a stepped portion between an insulating substrate and a member having a different thermal conductivity in a part thereof. It is something.

Hereinafter, the components and functions of the present invention will be explained in detail.

The fine particle film in the present invention is a film of conductive fine particles having a particle size of 10 to several μm, and examples of the thin film conductor include a conductive fine particle film and a carbon thin film in which these conductive fine particles are dispersed. These films are formed between the electrodes by a gas deposition method, a dispersion coating method, or the like.

Various methods can be considered for forming an electron emitting region with a fixed shape, examples of which are as follows.

FIG. 3 is an element configuration diagram showing one embodiment of the present invention.

In the figure, 3I is an insulating substrate, 32 is an electron emission part defining member, 33 and 34 are electrodes, and 35 is a fine particle film.

The electron-emitting device of the present invention is characterized in that an electron-emitting portion defining member 32 is provided in contrast to the electron-emitting device shown in FIG.

The shape and material of the electron emitting portion defining member mentioned here will be explained below.

The size of the step formed by the electron emission part defining member may be 0.1 to 10 μm in thickness.
It is even better if it is μm to 1 μm.

Further, the width should be narrower than the electrode spacing, and even better if it is 1/2 or less of the electrode spacing.

The electron emitting part defining member may be made of a material having a thermal conductivity different from that of the substrate, and it is necessary to select an appropriate material depending on the material of the particles, the spacing between the electrodes, and the difference in the electron emitting part defining member.

As for the effect, it is sufficient to use a material whose thermal conductivity is even slightly different from that of the insulating substrate. As a preferable condition, it is desirable that the thermal conductivity differs by a factor of two or more. For example, when blue plate glass is used for the insulating substrate, an insulating material such as alumina or a metal material such as Au is used. Further, by changing the thermal conductivity compared to the insulating substrate, the electron emitting portion can be formed on the top or side of the electron emitting portion defining member, or on the insulating substrate along the defining portion.

The distance between the electrodes 33 and 34 is preferably 0.1 μm to 100 μm, and generally 0.5 μm to 10 LLm is practical. Further, although the thickness of the 8-electron count regulating member 32 depends on the type of material, it is usually desirable to have a thickness of several hundred to several μm, and generally 0.1 μm to 1 μm is practical.

Next, an organic metal is dispersed and coated between the electrodes, and then baked to form a metal fine particle film between the electrodes. The diameter of the fine particles of the metal fine particle film is preferably +λ to several μm, and the material thereof may be a metal such as P d + A g + A u + T 1, or an oxide conductor conductive material such as Pdo or 5n02. You may use it.

When the fine particle film provided on the stepped portion as described above is energized, the electron emitting portion 36 is formed in a straight line along the step of the electron emitting portion defining member as shown in FIG. 3, unlike the conventional example described above. The electron emitting part does not meander like this. Such an electron emitting region can be formed on either the upper side, the lower side, or the side surface of the regulating member depending on the direction of current supply, the type of particulate material, the type and thickness of the electron emitting region defining member, and the like.

Of course, if the defining member is a curved line, the electron emitting portion is formed in a curved line along the member.

Current treatment methods include one in which a part of the particulate film is made high in resistance by heating with electricity to form an electron emitting part, and another in which part of the part of the particulate film is made to have a low resistance by being energized to form an electron emitting part. There are two, but you can use either one.

During this energization process, the structure of the fine particle film changes, forming discontinuous electron-emitting portions as described above. In fact, there are 3 steps
Although it is unclear what role No. 2 plays in the structural change, the inventors believe that the temperature distribution or electric field distribution becomes discontinuous near the stepped portion of the electron-emitting region defining member, which causes the electron-emitting region to change. It is assumed that the electron emitting portion is formed along the layered material. Further, controllability is further improved by using a material having a different thermal conductivity for the step member than that of a simple step member. Therefore, in addition to providing a material with a different thermal conductivity from the substrate between the electrodes, it can be expected that the same effect can be obtained by providing a member that makes the temperature and electric field discontinuous.

5 and 6 are cross-sectional views of an element showing an embodiment of the present invention. In addition to the triangular step 37 described above, the shape of the step formed by the electron emitting portion defining member is as shown in FIG. 6. Various shapes such as the step 38 at the top of the stairs can be considered, and have the same effect as the convex shape shown in FIG. 3 above.

The electron-emitting device of the present invention includes an electron-emitting region having a fixed shape, a particulate film sandwiching the electron-emitting part and electrically connected to each other, and an electrode for passing a current through the electron-emitting part and the particulate film. Compared to conventional devices, this device structure not only makes it possible to control the electron emission characteristics but also improves the reproducibility of the device.

If the electron-emitting device of the present invention is used in the image forming apparatus provided with the plurality of electron-emitting devices described above, the amount of electrons emitted from each device will be the same, so a good image without display unevenness will be formed. .

[Example] The present invention will be explained in more detail below using examples.

Fruit 1 eye milk ↓ Fig. 3 is a diagram of the element configuration of this experimental example, and Fig. 4 is an explanatory diagram showing its manufacturing method.

First, a method for manufacturing the electron-emitting device of this example will be schematically explained.

(2) The insulating substrate (quartz substrate) 31 is thoroughly cleaned, and electrodes 33 and 34 are formed using commonly used vapor deposition techniques such as photolithography and etching techniques. The electrode may be made of any material as long as it has conductivity, but in this example, it was formed using Ni metal. Practically speaking, it is desirable that the electrode spacing be set to 0.5 um to 20 um, and in this experimental example, it was set to a 5 um gap.

06 Next, the electron emission part defining member 32 was formed by a conventional thin film buttering process.The member was made of alumina, and had a width of 1 μm and a thickness of 1 μm.

00 Next, organic palladium is dispersed and coated between the electrodes 33 and 34. Organic palladium is Okuno Pharmaceutical Co., Ltd. CCP-42
30 was used.

A tape or resist film is provided in areas where it is not desired to disperse fine particles, and then organic palladium is applied by a dipping method or a spinner method. Next, it is fired at 300° C. for 1 hour to disperse organic palladium and form a fine particle film containing a mixture of palladium and palladium oxide. Next, a particulate film 35 was created at a predetermined position by peeling off the tape or resist film. The width W of the fine particle film (in the direction perpendicular to the cross section in FIG. 4) may be of any value, but in this example, it is 1 mm.
And so. At this time, the diameters of the fine particles of palladium and palladium oxide were both 10 to 150, but the present invention is not limited to this.

(1) First, the electrode 33 was connected to a power source so that the electrode 34 was connected to the negative side and the electrode 34 was connected to the positive side, and the particulate film 35 was energized. As a result, an electron emitting section 36 was formed along the step of the electron emitting section defining member 32, as shown in FIG.

Here, the thickness of the fine particle film before energization treatment ranges from several tens to 200 mm.
People are practical but not limited to this. Incidentally, the sheet resistance of the fine particle film at this time is approximately 10 3 to 10 I0 Ω/mouth. Further, the thickness of the particulate film 35 is determined by the regulating member 32.
It is considered that the area is almost uniform between the electrodes, including the area of .

In the energization process in this example, the current flow direction was from the electrode 34 to the electrode 33 side, and by setting in this way, the electron emitting portion could be formed at the above-mentioned position with good reproducibility.

When the electron-emitting device of this example was compared with a conventional electron-emitting device not provided with an electron emission pressure regulating member, almost the same value was obtained in terms of electron emission efficiency. Next, a comparison of the shapes of the electron-emitting portion shows that although the conventional device has a large meandering shape over a width of 1 mm, the electron-emitting device of this embodiment has a substantially straight line along the step of the electron-emitting portion defining member 32. An electron emitting region was formed. Being able to accurately set the position of the electron-emitting region is extremely important when considering applications. For example, in order to accurately control the deflection and modulation of electrons emitted from an element, the position of the electron emitting portion must be accurately located. Therefore, the eight-electron device of this embodiment provides a surface conduction electron-emitting device whose position can be designed.

15±1 FIG. 7 is an element configuration diagram of this embodiment.

This example has almost the same shape as Example 1, but the particulate film 35 was created by a gas deposition method, and 39 on the side surface of the electron emitting part defining member 32 is an electron emitting part. be.

Next, the manufacturing method of this example will be explained.

(2) Made from the same material and by the same method as in Example 1-(2).

■, Same as Example 1-■ ■, Same as Example 1-■ 03 Next, in order to form a fine particle film at a predetermined position, a metal mask is placed between the electrodes 33 and 34, and a gas deposition method is applied. A particulate film 35 was created. The material is Au, Ag,
Although metals such as Ti, Sn, and Pd or any other conductive fine particles may be used, pb was used in this example. Further, the particle size was 50 to 150 particles, but this example is not based on this.

■, Same as Example 1-■.

Through the above steps, the electron emitting section 39 of this embodiment is
As shown in the figure, it is formed on the stepped side surface of the electron emission part defining member 32. This is thought to be based on the method of creating fine particles using the gas deposition method. In this example, since the particles are sprayed from a direction substantially perpendicular to the substrate using the gas deposition method, the thickness of the particle film is thin (formed) on the side surface of the stepped portion, and is formed on the side surface of the regulating member 32 by the energization process. I guess it is.

As a result of the same study as in Example 1, this example had similar effects.

FIG. 8 is a block diagram showing the image forming apparatus of this embodiment. The planar electron source of this example is one in which a plurality of electron-emitting devices of Example 1 are arranged, and in particular, several line electron sources in which electron-emitting devices are arranged in parallel between electrodes 33 and 34 are arranged regularly on a substrate. It was established.

In the figure, 41 is a grid electrode, 42 is an electron passing hole, 43 is a glass plate, 44 is a phosphor, 45 is a metal back made of aluminum material, 46 is a face plate, 4
7 is a bright spot of the phosphor.

In this embodiment, the grid electrode 41 consists of a plurality of line electrode groups and is arranged in a direction perpendicular to the electrode group of the planar electron source. The electron passing hole 42 is provided almost vertically above the electron emitting section 36, and uses the grid electrode 41 as a signal electrode and the line electron source group as a scanning electrode to form an image by performing XY matrix driving.

The face plate 46 has a transparent glass plate 43 coated with a phosphor 44 uniformly, and a metal back 45 provided thereon.

In the image forming apparatus of this embodiment, the electrode 33 and the electrode 34
By applying a voltage of 14V to each electron emitting part 36
By emitting electrons from the grid electrode 41 and applying an appropriate voltage to the grid electrode 41, the electrons were drawn out and collided with the phosphor 44. This image forming apparatus naturally has a vacuum degree of 1X.
It was placed in an environment of 10-'TorrXIX10-'Torr, and a voltage of 500 to 5000V was applied to the phosphor.

In this experiment, a comparison was made with a similar image forming apparatus without the electron emitting section defining member 32 (step), and the following results were obtained.

1) In this example, since the amount of electrons emitted from each electron emitting section was equal, a display screen with uniform brightness was obtained.

2) In this example, since the position of each electron emitting part was accurately determined, the bright spots on the phosphor had almost the same shape and were regularly arranged.

In contrast, in the device without a step, the shape and pitch of the bright spots varied depending on the location.

Therefore, this embodiment is effective in obtaining color images and high-definition images.

In addition, the results of visual evaluation of the dispersion of 100 elements in the case where an electron emission part defining member with a width of 1 μm is provided in elements with an electrode spacing of 20 μm are shown below.

In this embodiment, only the image forming apparatus has been described, but in addition to the phosphor, the image forming members include all members whose state changes when the electron beam collides with them, such as resist materials and thin film metals. There are various types of electron beam application devices, such as recording devices, storage devices, and electron beam lithography devices. If so, it will have the same effect.

Husband 1” Pull A The element configuration of this example is shown in FIG.

This example uses the same manufacturing method and materials as Example 1, but Ni
A thin metal film 40 is provided. The electron emitting section 36 in this case was formed at the same position as in Example 1.3.

Further, as a result of the same study as in Example 1.2.3, this example had similar effects.

[Effects of the Invention] As explained above, by forming an electron emitting portion with a fixed shape, the following effects can be obtained as an electron emitting device or an image forming apparatus.

(2) Not only can electronic characteristics such as the amount of electron emission and electron emission efficiency be controlled, but it has also become possible to manufacture devices with less variation in characteristics between devices.

(2) Image display with uniform luminance can be obtained as an image forming apparatus.

(2) Since the position of the electron emitting part is accurately determined, it is now possible to display an image with a uniform bright spot shape of the phosphor in the image forming apparatus.

(2) Since the position of the electron emitting portion is accurately determined, the shape design of the modulation electrode and the control system of the image forming apparatus are simplified.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electron-emitting device produced by conventional electrical heating. FIG. 2 is a configuration diagram of an electron-emitting device produced by applying current to a conventional fine particle film and a thin film conductor containing fine particles. FIG. 3 is a configuration diagram of an electron-emitting device in Example 1 of the present invention. FIG. 4 is an explanatory diagram showing a method of manufacturing an electron-emitting device in Example 1 of the present invention. 5 and 6 are cross-sectional views of a device step portion showing other embodiments of the present invention, and FIG. 6 is a configuration diagram of an electron-emitting device in Example 4. FIG. 7 is a configuration diagram of an electron-emitting device in Example 2. FIG. 8 is a configuration diagram of an image forming apparatus in Example 3. FIG. 9 is a cross-sectional view of an electron-emitting device in Example 4. 1.2, 11, 12, 33.34... Electrode 3... Thin film 4.15... Substrate 5.14, 36.39... Electron number part 13.35...
- Particulate film 31... Insulating substrate (quartz substrate) 32.37.38... Electron emission part defining member 40...
Metal thin film 41...grid electrode 42...electron passing hole 43...glass body 44...phosphor 45...metal back 46...face plate 47...bright spot electron emission of phosphor Typical configuration diagram of the element Figure 4

Claims (2)

[Claims] (1) An electron-emitting device comprising, on an insulating substrate having a stepped portion, a low-resistance portion made of fine particles electrically connected across the stepped portion, and a pair of electrodes for supplying current to the low-resistance portion. An electron-emitting device characterized in that the step portion of the device is made of a member having a thermal conductivity different from that of the insulating substrate, and the electron-emitting portion of the device is located near the step. (2) A vacuum container includes at least an electron source in which a plurality of electron-emitting devices according to claim 1 are arranged, and an image forming member that forms an image by irradiation with electrons emitted from the electron source. image forming device.