JP2001143607A - Electron emission element, electron source and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron emission element that can set both electron emission efficiency and convergence of the electron beam as desired, and to provide an electron source and an image forming device. SOLUTION: A plurality of second electrode parts 4 are laminated on their respective insulation layer 3 projected on a substrate, so that the convergence of the electron beam is controlled as desired together with efficient electron emission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron-emitting device and an electron source using the same, for example, an image forming apparatus such as a display device and an exposure device.

[0002]

2. Description of the Related Art Conventionally, as this type of electron-emitting device,
Two types of thermionic emission devices and cold cathode electron emission devices are known. Field emission type (hereinafter referred to as F
E type), metal / insulating layer / metal type (hereinafter MIM)
And a surface conduction electron-emitting device.

[0003] As an example of the FE type, W. P. Dyke &
W. W. Dolan, "FieldEmissio
n ", Advance in Electron P
physics, 8, 89 (1956) or C.I.
A. Spindt, “PHYSICAL Proper
ties of thin-film field em
Mission cathodes with molly
bdenium cones ", J. Appl. Phys.
s. , 47, 5248 (1976).

Further, an electron-emitting device has been proposed which emits electrons from a hole formed in a gate electrode as a shape other than the Spindt type. For example, Japanese Patent Application Laid-Open No. Hei 8-96703
Japanese Patent Application Laid-Open Publication No. H11-15064 proposes an electron-emitting device in which a 1-μm through hole is formed in a 1-μm-thick insulating layer and a 0.2-μm-thick gate electrode, and electrons are emitted from a diamond thin film at the bottom of the hole.

As an example of the MIM type, a report by Mead (CA Mead, J. Appl. Phys., 3)
2,646 (1961)).

As an example of a surface conduction electron-emitting device, a report by Elinson (MI Elinson Radio) is given.
Eng. Electron Phys. , 10 (19
65)).

The surface-driven electron-emitting device utilizes a phenomenon in which an electron is emitted by passing a current through a small-area thin film formed on a substrate in parallel with the film surface. Examples of the surface conduction electron-emitting device include a device using an SnO ₂ thin film and a device using an Au thin film described in the above-mentioned report of Elinson (G. Dittmer. Thin Sol).
id Films, 9, 317 (1972)), In ₂
O ₃ / SnO ₂ thin film (M. Hartwell
and C.I. G. FIG. Fonstad, IEEE Tran
s. ED Conf. , 519 (1975)), using a carbon thin film (Araki et al., Vacuum, Vol. 26, No. 1)
No. 22, p. 22 (1983)).

In these surface-conduction electron-emitting devices, an electron-emitting portion is generally formed by conducting an energization process called energization forming on a conductive thin film before electron emission. That is, the energization forming is to apply a voltage to both ends of the conductive thin film and apply a current to locally destroy, deform, or alter the conductive thin film, thereby forming an electron emission portion in an electrically high-resistance state. . In the electron emitting portion, a gap is generated in a part of the conductive thin film, and electrons are emitted from the vicinity of the gap.

Conventionally, as an example of arranging a large number of surface conduction electron-emitting devices, a surface conduction electron-emitting device is arranged in parallel, and both ends (both device electrodes) of each surface conduction electron-emitting device are wired. (Common wiring), an electron source in which a number of rows each connected by a common line are arranged (ladder-like arrangement) (for example, JP-A-64-31332, JP-A-1-29374)
JP-A-2-257552).

In particular, in a display device as an image forming device, a flat display device equivalent to a display device using a liquid crystal can be provided, and a self-luminous display device which does not require a backlight is provided. A display device has been proposed in which an electron source in which a number of surface conduction electron-emitting devices are arranged and a phosphor that emits visible light when irradiated with an electron beam from the electron source are combined (US Pat. No. 5,068,893). .

[0011]

However, in the case of the above-described prior art, the following problems have occurred.

In order to apply the electron-emitting device to an image forming apparatus such as a display device, it is necessary to provide an emission current for causing the phosphor to emit light with sufficient luminance. In addition, as the definition of the display is increased, the electron beam is required to have a small electron beam diameter when the phosphor is irradiated with the electron.

In a conventional FE type, particularly a Spindt type electron-emitting device, a large emission current density is required from one emission point in order to obtain an emission current required for a display. This causes thermal destruction of the electron emission portion, and F
This limits the life of the E element.

In an electron-emitting device having a hole-shaped gate electrode of the Spindt type or the like, the electric field around the hole acts to spread the emitted electrons. That is, since an electric field that increases the electron beam is formed, it is inconvenient for application to a high-definition display.

In order to realize a particularly bright display, it is desirable to apply an acceleration voltage of 5 kV or more to the phosphor. Therefore, in order to suppress the discharge breakdown phenomenon, the distance between the electron-emitting device and the phosphor needs to be about 1 mm or more. However, the electrons emitted while traveling this distance tend to spread.

In the structure for converging the electron beam,
An electrode having another potential called a grid electrode may be arranged above the electron emitting portion. In this case, there is a problem that the configuration becomes complicated.

On the other hand, there has been proposed a structure in which another focusing electrode having a different potential is arranged near the emitting portion of the electron-emitting device. This method is effective for reducing the size of the beam from the electron-emitting device, but the addition of the converging structure has complicated the method of manufacturing the electron-emitting device.

On the other hand, the MIM type electron-emitting device has a structure in which an insulator is provided between a lower electrode and an upper electrode, and a voltage is applied between the two electrodes to extract electrons. The beam size can be reduced because the directions of the electrons to be emitted coincide with each other and the potential is not distorted in a vacuum, but the efficiency of electron emission deteriorates because electrons are scattered between the insulating layer and the upper electrode. It is common.

That is, when the application to a display is considered, an electron-emitting device that satisfies that the diameter of the emitted electron beam is small, the electron-emitting area is large, and electrons can be emitted at a relatively low voltage is required. However, the above-described conventional electron-emitting devices do not satisfy the above-described performance, and a higher-performance electron-emitting device is required to realize a high-brightness, high-definition image forming apparatus.

FIG. 17 shows an example of a conventional surface conduction electron-emitting device. 101 is a substrate, 102 and 103 are electrodes, 104 is a conductive film, and 105 is a gap.

In the surface conduction electron-emitting device, there is generally a trade-off relationship between the efficiency of electron emission and the convergence of the diameter of the emitted electron beam. As individual solutions, a proposal for improving the efficiency of electron emission (Japanese Patent Laid-Open No. 9-82214) and a proposal for converging the diameter of the emitted electron beam (Japanese Patent Laid-Open No. 2-1121)
No. 25). However, none of the proposals has been able to be set so as to exert effects on both the efficiency of electron emission and the convergence of the diameter of the emitted electron beam.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention that desired settings can be made for both efficiency of electron emission and convergence of an emitted electron beam diameter. Another object of the present invention is to provide a high-performance electron-emitting device, an electron source and an image forming apparatus.

[0023]

According to the present invention, there is provided an electron-emitting device comprising: a first electrode having a low potential provided on a substrate; And a conductive film electrically connected between the first electrode and the second electrode and partially having a gap from which electrons are emitted. In the electron-emitting device, an uneven structure is provided by arranging a plurality of protrusions in which the second electrode is stacked on the first electrode via an insulating layer,
By changing the potential arrangement near the gap by changing the width of the concave and convex portions of the concavo-convex structure, the state of the electric field was defined to set the electron emission characteristics of the electrons emitted from the gap. It is characterized by the following.

Therefore, because of the stacked structure, the modulation structure of the electron emission characteristics, for example, the electron emission efficiency and the diameter of the emitted electron beam, can be formed very easily and at a high density, and the performance of the electron emission element can be improved. Desirable settings can be made for both the efficiency of emission and the convergence of the diameter of the emitted electron beam.

Further, the potential distribution of the laminated structure can be easily prepared by setting the first electrode to a low potential and the second electrode to a high potential, and it is possible to increase the electron emission efficiency by reducing the scattering of emitted electrons. .

It is preferable that the concavo-convex structure is a periodic structure in which concave portions and convex portions are periodically continuous.

As a result, the same concave portions and convex portions are repeated, so that the potential distribution can be changed and the number of emission points of electrons can be increased, so that the electron emission characteristics such as the electron emission efficiency and the emission electron beam diameter can be increased. Is stable, and the manufacture of the electron-emitting device is facilitated.

An anode electrode is provided at a distance H from the first electrode. When an anode voltage Va is applied to the anode electrode and a drive voltage Vf is applied between the first electrode and the second electrode. , Characteristic distance Xs = (H
If (Vf) / (π · Va), the distance from the gap to the second electrode is preferably less than 200 times the gap width or less than or equal to the characteristic distance Xs.

As a result, the scattering of emitted electrons can be reduced, and the electron emission efficiency can be increased.

An anode electrode arranged at a distance H from the first electrode, wherein an anode voltage Va is applied to the anode electrode and a driving voltage Vf is applied between the first electrode and the second electrode. , Characteristic distance Xs = (H
Assuming that (Vf) / (π · Va), it is preferable that the width of the concave portion and the convex portion is smaller than 10 times the characteristic distance Xs, and the ratio of the width of the concave portion to the width of the convex portion is 1 or less.

As a result, the potential distribution changes, the confusion of the emitted electrons is reduced, and the electron emission efficiency is increased.

It is preferable that both ends of the concave-convex structure are terminated by a first electrode which is a concave portion.

Thus, the convergence of the electron beam due to the sandwich of the uneven structure between the low potentials of the first electrode acts, and the electron beam can be converged.

An anode electrode is provided at a distance H from the first electrode, and when an anode voltage Va is applied to the anode electrode and a drive voltage Vf is applied between the first electrode and the second electrode. , Characteristic distance Xs = (H
Assuming that (Vf) / (π · Va), it is preferable that the width of the first electrode terminated at both ends of the concave-convex structure is provided to be at least 10 times the characteristic distance Xs.

Thus, even when a plurality of electron-emitting devices are arranged, the electron-emitting devices are not affected by other electron-emitting devices, and the electron-emitting characteristics, such as the electron-emitting efficiency and the like, can be improved.
The diameter of the emitted electron beam becomes stable.

It is preferable that the gap of the conductive film is provided only in the central region of the uneven structure.

As a result, the convergence potential is further increased.
The electron beam diameter can be more converged.

An anode electrode is provided at a distance H from the first electrode, and when an anode voltage Va is applied to the anode electrode and a drive voltage Vf is applied between the first electrode and the second electrode. , Characteristic distance Xs = (H
When Vf) / (π · Va), the width of the concave portion and the convex portion is provided to be smaller than ４ of the characteristic distance Xs, and
It is preferable that the ratio of the width of the concave portion to the width of the convex portion is set to 1 or less.

Thus, even when the lengths of the concave portions and the convex portions are short, it is possible to increase the number of the concave portions and the convex portions so that the electron emission amount is not reduced, and to broaden the electron beam distribution. In addition, it is possible to prevent the phosphor or the like that receives the electron beam from being damaged.

An anode electrode, to which electrons emitted from the electron-emitting device reach, is provided with two convex portions on the concave-convex structure. Of the side walls of the convex portion, the conductive film is formed on both side walls of the concave-convex structure. It is preferable that the gap is provided, and the two gaps provided are spaced apart such that electrons emitted from the gap at the anode electrode reach substantially one point.

Thus, the electron beam can be focused on one point, and the amount of emitted electrons can be increased.

In order to achieve the above object, an electron source according to the present invention is characterized in that a plurality of the above-mentioned electron-emitting devices are arranged on a substrate.

Also, a plurality of the above-mentioned electron-emitting devices are arranged in a matrix wiring.

A first electrode; an insulating layer formed on the first electrode; a second electrode formed on the insulating layer;
A first conductive film connected to an electrode and disposed on the insulating layer; and a first conductive film connected to the second electrode and disposed on the insulating layer;
A second conductive film facing the first conductive film with a gap therebetween;
And a voltage applying means for applying a voltage higher than the voltage applied to the first electrode to the second electrode. It is preferable that the plurality of stacked bodies are disposed on the substrate with a gap therebetween, and the second conductive films forming each of the adjacent stacked bodies are connected to each other. .

It is preferable that the second conductive films are connected on the substrate.

A first electrode; an insulating layer formed on the first electrode; a second electrode formed on the insulating layer;
A first conductive film connected to an electrode and disposed on the insulating layer; and a first conductive film connected to the second electrode and disposed on the insulating layer;
A second conductive film facing the first conductive film with a gap therebetween;
And a voltage applying means for applying a voltage higher than the voltage applied to the first electrode to the second electrode. An electron source having the plurality of laminates arranged on the substrate with a gap therebetween, wherein an interval between the adjacent laminates and a width of the second electrode in the interval direction are different. Is preferred.

In order to achieve the above object, an image forming apparatus according to the present invention includes the above-described electron-emitting device and an image forming member.

It is preferable that a driving device for controlling an electron beam composed of electrons emitted from the electron-emitting device in accordance with an information signal is provided.

An image forming apparatus having an electron source and an image forming member, wherein the electron source is the above-mentioned electron source.

[0050]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The materials, shapes, relative arrangements, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

FIGS. 1 and 2 are views showing an example of the electron-emitting device according to the present embodiment, wherein (a) is a cross-sectional view and (b) is a plan view. FIG. 3 is a diagram illustrating a driving state of the electron-emitting device according to the present embodiment. FIG. 4, FIG.
FIG. 3 is a diagram illustrating an example of a method for manufacturing the electron-emitting device in FIG. 2.

1 and 2, reference numeral 1 denotes a substrate, and 2 denotes a first substrate.
Electrodes 3, 3 are insulating layers, 4 is a second electrode, 5 is a conductive film, and 6 is a gap.

In FIG. 3, reference numeral 8 denotes an anode electrode, 9 denotes a power source for applying a voltage between the first electrode 2 and the second electrode 4,
Is a power supply for applying a voltage to the anode electrode 8.

The electron-emitting device of this embodiment is a surface-conduction electron-emitting device in which electrons are emitted from the gap 6 by a voltage applied between a pair of electrodes, that is, the first electrode 2 and the second electrode 4. is there.

In particular, the surface conduction type electron-emitting device has a so-called vertical type electron-emitting portion in which the gaps 6 are present on the side walls of the insulating layer 3 by laminating the insulating layers 3 between the electrodes 2 and 4 and between them. Have.

In the present embodiment, an uneven structure in which a plurality of convex portions on which the second electrodes 4 are stacked via the insulating layer 3 is arranged so that a plurality of side walls of the insulating layer 3 are present. FIG. 1 shows an electron-emitting device having a concave structure, and FIG. 2 shows an electron-emitting device having a convex structure.

The convex structure and the concave structure are defined by the difference between the ratio of the width of the concave portion to the width of the convex portion. A structure having a ratio of the width of the concave portion to the width of the convex portion of 1 or more is called a concave structure. Is referred to as a convex structure (a structure having a ratio of 1 is considered to be a concave structure or a convex structure, and may be used without particular distinction).

The period of the uneven structure is P1 in the concave structure,
The convex structure is defined as P2, the concave structure is defined as w1 and the convex portion width is w2, and the convex structure is defined as w3 and w4.

In FIGS. 1 and 2, the second electrode 4 is patterned as one electrode. Therefore,
When driven as shown in FIG. 3, the same potential is applied to the second electrode 4.

Further, in the present embodiment, the uneven structure is a structure modulated on the x-axis, and is uniform in the length L1 in the y-axis direction. The gap 6 is formed in a region where the conductive film 5 exists, and is therefore parallel to the y-axis and has a length L2.

In the present embodiment, a drive voltage Vf is applied by a power supply 9 for applying a voltage between the first electrode 2 and the second electrode 4, and an element current If flows. For the electron-emitting device,
A low potential is applied to the first electrode 2 and a high potential is applied to the second electrode 4. Further, an anode voltage Va is given by a power supply 10 for applying a voltage to the anode electrode 8. Gap 6
The electrons emitted from are captured by the anode electrode 8 and the emission current Ie flows.

Hereinafter, a method of manufacturing the electron-emitting device according to the present embodiment shown in FIG. 4 will be described.

SiO ₂ was laminated by sputtering or the like on a surface of which the surface was sufficiently cleaned in advance, for example, quartz glass, glass with a reduced content of impurities such as Na, blue plate glass, blue plate glass, and a Si substrate. The first electrode 2 is formed on a laminated body, an insulating substrate 1 made of ceramics such as alumina (FIG. 4A).

Further, an insulating layer 3 and a second electrode 4 are deposited (FIG. 4B).

Next, a resist pattern 21 is formed in a desired portion by a photolithography process (FIG. 4).
(C)).

Next, the insulating layer 3 and the second electrode 4 are formed along the resist pattern 21 by etching (FIG. 4D). Note that in this step, an etching method may be selected depending on the material of each electrode and the insulating layer.

The first electrode 2 and the second electrode 4 are laminated by a general vacuum film forming technique such as an evaporation method and a sputtering method, and are formed by a photolithography technique. As a material of the first electrode 2 and the second electrode 4, a general conductor material is used, for example, Ni, Cr, Au, Mo, W, Pt, Ti, A
metals or alloys such as l, Cu, Pd and Pd, A
a printed conductor composed of a metal such as u, RuO ₂ , Pd—Ag or a metal oxide and glass; In ₂ O ₃ —SnO
_{2 and the} like, and are appropriately selected from transparent conductors and semiconductor materials such as polysilicon.

Here, the thickness of the first electrode 2 is set in a range from several nm to several mm.

The insulating layer 3 is formed by a general vacuum film forming method such as a vapor deposition method and a sputtering method, a thermal oxidation method, an anodic oxidation method and the like. The material of the insulating layer 3 is preferably SiO ₂ , and a material having a high withstand voltage that can withstand a high electric field, such as other oxides and nitrides, is selected.

The thickness of the insulating layer 3 is from several nm to several tens μm.
Is preferably set in the range of several tens nm to several μm.
It is.

As described above, the second electrode 4 may be made of the same material as the first electrode or a different material.

The thickness of the second electrode 4 is set in the range of several nm to several μm, but is preferably thinner in order to improve the electron emission efficiency, and is preferably several nm to several tens nm. Good. When the film thickness is small, a heat-resistant material is particularly desirable.

With the above, a basic uneven structure is formed.
In the steps up to this point, a general photolithography step and an etching step were used.
Other methods may be used.

Next, a step of forming a gap 6 between the first electrode 2 and the second electrode 4 and forming an electron-emitting portion in the gap 6 is performed.

For this purpose, a conductive film 5 is further formed along the uneven structure formed by the first electrode 2 and the second electrode 4 (FIG. 4E).

The material of the conductive film 5 is Pd, Pt, Ru,
Ag, Au, Ti, In, Cu, Cr, Fe, Zn, S
metal such as n, Ta, W, Pd, Pt-Pd, Pd-Ag
Alloys such as PdO, SnO ₂ , In ₂ O ₃ , PbO, Sb ₂
Oxide such as O ₃ , boride such as HfB ₂ , ZrB ₂ , LaB ₆ , carbide such as TiC, ZrC, SiC, WC, Ti
It is appropriately selected from nitrogen such as N, ZrN, and HfN, semiconductors such as Si and Ge, organic polymer materials, carbon and carbon compounds such as amorphous carbon, graphite, and diamond-like carbon.

The thickness of the conductive film 5 ranges from several Å to several hundreds n.
m, but is designed with resistance and step coverage.

Further, a voltage is applied between the first electrode 2 and the second electrode 4 to perform a step called an energization forming step to form a gap 6 (FIG. 4F).

In the energization forming, the voltage waveform is preferably a pulse waveform. The energization forming may be performed in a vacuum atmosphere as in the subsequent activation step.

The energization forming process is terminated when a voltage is applied to the extent that the conductive film 5 is not destroyed during the pulse interval, the current is measured, and the resistance is detected. When the resistance becomes 1 MΩ or more, Hiiragi is over.

The energization forming step is not limited to the energization forming but includes a process for forming a local high resistance state on the conductive film 5.

Further, there is a case where the activation and stabilization steps are performed after the electron-emitting device manufactured as described above is placed in a vacuum vessel and evacuated to a vacuum atmosphere.

The activation step is a step in which the element current If and the emission current Ie are remarkably changed to form a shape capable of emitting electrons at a low voltage, and carbon and a carbon compound are formed in the gap 6 formed in the forming step. It is to pile up.

In the activation step, for example, an organic gas is introduced into a vacuum vessel from an organic gas supply source, and a voltage is applied to the first electrode 2 and the second electrode 4 in an atmosphere containing an organic substance gas. The voltage waveform is applied repeatedly as a pulse waveform. For this, there are a method of continuously applying a pulse having a pulse peak value of a constant voltage, and a method of applying a voltage pulse while increasing the pulse peak value.

The preferable gas partial pressure of the organic substance when producing the carbon varies depending on the form of the carbon, the shape of the vacuum vessel, the type of the organic substance, and the like, and is appropriately set according to the case.

Suitable organic substances include aliphatic hydrocarbons of alkanes and alkenes, aromatic hydrocarbons, alcohols, aldehydes, ketones, amines, and organic acids such as phenol, carboxylic acid and sulfonic acid. Specifically, saturated hydrocarbons represented by C _n H _{2n + 2} such as methane, ethane and propane; unsaturated hydrocarbons represented by a composition formula such as C _n H _2n such as ethylene and propylene; benzene , Toluene, methanol, ethanol, formaldehyde, acetaldehyde, acetone, methyl ethyl ketone, methylamine, ethylamine, phenol, formic acid, acetic acid, propionic acid and the like.

Further, after the activation step, a process called a stabilization step is performed. This step is a step of exhausting the organic substance in the vacuum vessel, and the pressure in the vacuum vessel is
1.3 × 10 ⁻⁵ Pa or less is preferable, and 1.3 × 1 ⁻⁵ Pa or less is more preferable.
0 ^-6 Pa or less is particularly preferred.

When the inside of the vacuum vessel is evacuated, a vacuum evacuation system using no oil, such as a sorption pump or an ion pump, is preferable so that oil or the like generated from the apparatus is mixed and does not affect the element characteristics.

Further, when the vacuum container is evacuated, it is preferable to heat the entire vacuum container to facilitate evacuating the inner wall of the vacuum container and the like substance molecules adsorbed on the electron-emitting device.

The heating temperature at this time is from 80 ° C. to 200 ° C.
Is preferably 5 hours or more, but is not particularly limited to this condition, and is appropriately selected depending on the size and shape of the vacuum vessel, the configuration of the electron-emitting device, and the like.

The operation of the electron-emitting device in the present embodiment will be described with reference to FIGS. 5, 6, 17, and 18.

First, a description will be given of high efficiency and reduction of the beam size as general functions of the present embodiment. For this reason, the present embodiment will be described in comparison with a conventional flat surface conduction electron-emitting device. Further, in order to explain the effects of the present embodiment in detail, first, the size effect of each of the concave structure and the convex structure will be described, and further, a specific operation in the case of having a plurality of uneven structures according to the present embodiment. explain.

First, the general effect of improving the efficiency of the electron-emitting device in the present embodiment will be described. This is because, in the present invention, the gap 6 exists on the side wall of the uneven structure, the high-potential electrode (second electrode 4) is on the anode electrode 8 side, and the low-potential electrode (first electrode 2) is located across the gap 6. This is the effect of the opposite.

For comparison, the efficiency of a conventional planar surface conduction electron-emitting device will be described.

FIG. 17 is a diagram of a conventional surface conduction electron-emitting device, and FIG. 18 is a conventional surface conduction electron-emitting device.
FIG. 3 is a diagram showing a potential distribution of a child and an electron arrival position. FIG.
In FIG. 18, 101 is a substrate, 102 and 103 are electrodes, 104 is a conductive film, 105 is a gap, and 106 is an anode electrode.

SID '98 Digest, Okuda,
According to et al, there is a gap 105 on the order of nm between opposing electrodes, and when a driving voltage Vf is applied to this element, electrons are emitted from the tip of the low potential electrode to the opposing high potential electrode (or injected through the substrate). It is known that the electrons are isotropically scattered again at the tip of the high-potential electrode (assuming that the electrons are emitted isotropically from the tip of the high-potential electrode. And numerical calculation predictions are found to be consistent.)

Most of the electrons emitted from the low potential electrode are repeatedly elastically scattered (multiple scattering) several times on the high potential electrode, and electrons exceeding the characteristic distance Xs reach the anode electrode 106.

The characteristic distance Xs is represented by the following expression: Xs = D / 2√ (1+ (2H · Vf / πVa · D) 2) ≒ (H · Vf) / (π · Va) (1) Is a distance between the electron-emitting device and the anode electrode 106, π is a circular constant, D is a gap width formed in the electron-emitting portion, Vf is a driving voltage, and Va is a voltage of the anode electrode 106.

The second approximation of the above equation (1) is Vf / D
It is satisfied in the case of で は Va / H (it is sufficiently satisfied in the case of a normal surface conduction electron-emitting device).

As shown in FIG. 18, the characteristic distance Xs is, as shown in FIG. 18, from the electron emission portion to the point where the surface at the same potential as the high potential electrode intersects the high potential electrode in the equipotential distribution appearing in vacuum. Expressed as the distance of

The electron emission efficiency is governed by a decrease in the number of electrons due to the fact that the electrons emitted from the gap 105 are partially absorbed by the high potential electrode by multiple scattering until the electrons exceed the Xs. Although the ratio (scattering coefficient) β scattered by the collision of electrons of about several tens eV is not clear, it is estimated to be about 0.1 to 0.5 per one scattering. Since β is equal to or less than 1 in such a scattering mechanism, it can be seen that the amount of electrons extracted in a vacuum decreases with a power as the number of scattering increases.

Therefore, in the conventional surface conduction electron-emitting device as shown in FIG. 17, as shown in FIG.
5 are scattered at least once on the opposing high-potential electrode within Xs, and many electrons are scattered a plurality of times. As a result, the number of electrons taken in and disappearing in the high-potential electrode increases, and the electron emission efficiency increases. Decrease.

From the above-described mechanism, it can be understood that the electron emission efficiency can be increased by suppressing the scattering of the emitted electrons.

On the other hand, an improvement in the efficiency of electron emission in the electron-emitting device of the present embodiment will be described.

The electron-emitting device of this embodiment shown in FIGS. 1 and 2 has a structure in which the first electrode 2, the insulating layer 3, and the second electrode 4 are stacked. As in the conventional electron-emitting device, a drive voltage Vf for driving the electron-emitting device is applied between the first electrode 2 and the second electrode 3, and an element current If flows.

At this time, the conductive film 5 and the first electrode 2 side are connected to the low potential electrode with the gap 6 therebetween, and similarly, the conductive film 5 and the second electrode
The electrode 4 is a high potential electrode.

As in the case of the above-mentioned conventional surface conduction electron-emitting device, electrons are emitted (or injected through the insulating layer 3) from the tip of the low-potential electrode to the opposing high-potential electrode. After the electrons are isotropically scattered again at the tip, the electrons are pulled up by the anode electrode 8 by the voltage Va applied between the electron-emitting device and the anode electrode 8 and captured by the anode electrode 8, and the emission current Ie flows. .

FIG. 5 is a diagram for explaining the number of times of scattering of the electron-emitting device in the present embodiment. Also in the electron-emitting device of the present embodiment, emitted electrons are scattered on the high potential electrode by the conductive film 5 and the second electrode 4 formed on the high potential side from the gap 6 and then travel to the anode electrode 8. .

Here, since the distance T1 from the gap 6 to the top of the second electrode 4 is short, electrons are less scattered from the region of the potential distribution dominated by the electric field between the high potential electrode and the low potential electrode near the electron-emitting device. The number of times you can escape increases with the number of times.

When the distance T1 from the gap 6 to the top of the second electrode 4 is shorter than the electron scattering distance T2, the electrons can reach the upper part of the electron-emitting device without scattering.
The electron emission efficiency is greatly improved.

It is estimated that the flight distance T2 of the scattered electrons is at most about 200 times the gap width D. In this case, the scattering distance of T1 is less than T1 <D × 200 or Xs or less. Can be suppressed. The interval D is several nm.
To about several tens nm.

As a desirable thickness of the high-potential electrode (second electrode 4), it is desirable that the thickness is as thin as possible from the viewpoint of efficiency. The voltage decreases due to the parasitic resistance. In addition, when the film is thin, heat dissipation of heat generated in the electron-emitting device is poor, and when the material does not have heat resistance, the film retreats during driving.

From the above viewpoint, the film thickness of the second electrode 4 is several n
It is set in the range of m to several hundred nm, and more preferably in the range of about several tens nm.

As described above, in the present embodiment, a high-potential electrode is made smaller than a low-potential electrode by forming a vertical electron-emitting device in which the first and second electrodes 2 and 4 and the insulating layer 3 are laminated. It can be arranged on the anode electrode 8 side. In addition, by taking the thickness of the second electrode 4 into consideration, a configuration in which T1 is sufficiently reduced can be achieved, and an electron-emitting device with high electron emission efficiency can be configured.

Next, the shape and width of the electron beam will be described.

First, an electron beam of a conventional planar surface conduction electron emitting device will be described. FIG. 18 shows the arrival positions of electrons in a conventional electron-emitting device.

As shown in FIG. 18, when the electron beam reaches the characteristic distance Xs in the upper part of the electron-emitting device, it largely deviates from the emission position, and is largely deviated by the distorted electric field in the upper part.

The electron beam diameter is almost equal to the amount of shift from immediately above the electron emission portion to the main arrival position of the electron beam. Therefore, the electron beam diameter is SID, 98Di.
It is known from Gest, Okuda, et al that Lh {4KhH} (Vf / Va) ... (2) Equation Lw {2KwH} (Vf / Va) ... (3) Equation

Here, Lh indicates the size of the electron beam in the vertical direction (y direction), and Lw indicates the size of the electron beam in the horizontal direction (x direction). Kh and Kw may vary slightly depending on the element structure, but are in the range of 0.8 to 1.0, and can be approximated by 1 in most cases.

On the other hand, an electron beam shape in a general vertical type electron-emitting device will be described.

First, the shape of the electron beam from one gap 6 when the high potential electrode and the low potential electrode continue infinitely on both sides is shown in FIG.

In this case, since the electrons reach the anode electrode 8 in an electron trajectory substantially similar to that of the conventional flat-type electron-emitting device, the main arrival position of the electrons is not different from the conventional flat-type electron-emitting device. However, the distribution of the electron beam shape changes depending on the gap position. Therefore, Kh and Kw in the above equations (2) and (3) become 1 or less, but their values differ depending on the structure.

Next, changes in the electron emission efficiency and the electron beam shape depending on the size of the concave structure and the convex structure according to the present embodiment will be described.

FIG. 7A is a schematic graph showing the effect that the electron emission efficiency of each concavo-convex structure depends on the size of the width of the concave and convex portions. In the graph, 51 indicates the characteristic of the concave structure, and 52 indicates the characteristic of the convex structure.

In the concavo-convex structure according to the present embodiment, a difference appears when the width of the concave portion and the convex portion is reduced. When the width of the concave portion and the convex portion is large, the electron emission portion (gap 6) can be regarded as the same as the conventional potential configuration sandwiched between the high potential and the low potential, but the width of the concave portion and the convex portion becomes small. In this case, in each electron-emitting portion, the influence of the potential configuration of the outer concave portion or convex portion cannot be ignored and is regarded as three potentials.

The three potentials are formed in a +-+ electron beam divergence type potential configuration in the concave structure, and in a-++-electron beam convergence type potential configuration in the convex configuration.

It can be said that the electron-emitting device generally has lower electron emission efficiency in the electron beam converging type than in the diverging type because the potential existing around it forms a decelerating potential.

FIG. 6 is a schematic view of an electron beam having each of the concavo-convex structures. Note that the electron beam diameter Lw_x is determined assuming that two gaps 6 exist on both side walls of the uneven structure.

In the present embodiment, the uneven structure is represented by x
The structure is made with respect to the axis, and the electric potential is also modulated in the x direction. Therefore, in the present embodiment, the effect of the potential modulation appears largely in the x direction.

On the other hand, there is no potential modulation in the y direction. However, the size effect of the electron beam also appears in the y direction, and especially when the width of the concave portion and the convex portion is reduced.

However, in the present embodiment, only the electron beam shape in the x direction, which is the modulation direction of the periodic structure, will be considered.

FIG. 6 shows that w1 and w have a concave structure and a convex structure.
When 3 is ∞ and sufficiently large, Lw_x = 2 × Lw + w1 concave structure Lw_x = 2 × Lw−w3 convex structure

FIG. 7B is a schematic graph showing the effect of changing the width of the concave and convex portions of the electron beam shape of each structure. 51 indicates the characteristic of the concave structure, and 52 indicates the characteristic of the convex structure.

In the electron beam shape, as the width of the concave and convex portions becomes smaller, the electron beam diameter also changes. The size at which the change starts coincides with the width of the concave portion and the convex portion where the efficiency changes.

In the convex structure, the reduction of the electron beam becomes remarkable due to the effect of the convergence potential due to the effect of reducing the width of the concave portion and the convex portion.

In the concave structure, the potential itself is a divergent potential. However, in the reduction effect by changing the width of the concave portion and the convex portion, the potential distribution near the electron emitting portion is flattened by the facing potential, and divergence is suppressed. However, the convergence effect is not as high as that of the convex structure.

Further, when the widths of the concave portion and the convex portion are reduced, electrons may not be emitted in the convergent potential configuration of the convex structure.

From the above, the effect of changing the width of the concave portion and the convex portion can be understood easily by dividing the type into three types. That is, the width of the concave portion and the convex portion is sufficiently large,
A region in which the electron-emitting portion is affected by a potential composed of only two potentials, a high potential and a low potential (type 1), and a region in which the electron-emitting portion is affected by three potentials, a high potential, a low potential, and a potential outside the region ( (type 2), a small-sized region (type 3) in which the electron beam is not emitted due to the convex structure.

As a result of the study, it has been found that the boundary of each type can be estimated using the above-mentioned characteristic distance Xs as a guideline. The boundary between type1 and type2 is approximately 10s of Xs.
And the boundary between type2 and type3 is approximately Xs
Was found to be 1/4.

This is a guideline for a single concavo-convex structure, and when the concave and convex portions are connected periodically, the effect of changing the width is not accurate. However, even in that case, the effect can be estimated depending on which type it belongs to.

Therefore, in the concavo-convex structure according to the present embodiment, by changing the width of the concave portion and the convex portion for each type, the structure is devised, so that the electron emission efficiency is high and the electron beam diameter is small. An electron-emitting device that converges or has a desired electron-emitting characteristic having a combination of those performances can be obtained.

That is, by using the fact that the potential arrangement near the gap 6 changes by changing the width of the concave and convex portions,
Since the electron emission characteristics of the electrons emitted from the gap 6 can be set by defining the state of the electric field, an electron emission element in which the width of the concave portion and the convex portion is changed is designed so that the electron emission characteristics, for example, the electron emission efficiency, The emission electron beam diameter can be set as desired.

Next, an electron source obtained by disposing a plurality of the above-described electron-emitting devices and an image forming apparatus using the same will be described with reference to FIGS. 8, 9, 10, and 11. FIG.

FIG. 8 is a wiring diagram of an electron source formed by arranging a large number of electron-emitting devices in an m × n matrix.

In the x-direction, m x-direction wirings (Dx1, Dx
x2, Dxm) 61 are arranged alternately, and in the y direction,
n y-directional wirings (Dy1, Dy2, Dy3, Dyn)
62 are formed. The first electrode 2 and the second electrode 4 constituting the electron-emitting device are electrically connected to an x-direction wiring 61 and a y-direction wiring 62, respectively. Reference numeral 60 denotes an electron source substrate on which a plurality of electron-emitting devices are arranged.

In the image forming apparatus of the present invention, the above-described electron-emitting devices are generally arranged in a simple matrix arrangement. That is, a plurality of electrodes arranged in a matrix in the x direction and the y direction, one of the electrodes of the plurality of electron-emitting devices arranged in the same column is commonly connected to a wiring in the x direction, and a plurality of electrodes arranged in the same column. The other electrode of the electron-emitting device is commonly connected to a wiring in the y-direction.

An array other than the simple matrix arrangement can be adopted. For example, connection is made at each end of a plurality of electron-emitting devices arranged in parallel, a large number of rows of electron-emitting devices are arranged (row direction), and the electron-emitting devices are arranged in a direction orthogonal to the wiring (column direction). There is also a ladder-like arrangement in which electrons from the electron-emitting devices are controlled and driven by a control electrode (grid electrode) arranged above.

FIG. 9 is a diagram showing an example in which a large number of the above-mentioned electron-emitting devices are arranged in a simple matrix. The same members as those in FIG. 8 are denoted by the same reference numerals.

A plurality of x-direction wirings 61 are formed in the x direction, and a plurality of y-direction wirings 62 are formed in the y direction. On the other hand, between the x direction wiring 61 and the y direction wiring 62, FIG.
The wirings 61 and 62 are electrically separated from each other by an insulating layer 63 shown in FIG. An x-direction wiring 61 and a y-direction wiring 62 are respectively provided on the first electrode 2 and the second electrode 4 constituting the electron-emitting device.
And are electrically connected.

The x-directional wiring 61 and the y-directional wiring 62 can be made of a conductive metal or the like formed by a vacuum evaporation method, a printing method, a sputtering method, or the like. Wiring material, film thickness,
The width is appropriately designed.

The insulating layer 63 is the first electrode 2 of the electron-emitting device.
It may be the same as the insulating layer 3 between the first and second electrodes 4, or may be provided separately therefrom. The insulating layer 63 is made of SiO ₂ or the like formed by using a vacuum deposition method, a printing method, a sputtering method, or the like. Its thickness and shape are
In particular, it is set appropriately so as to withstand the potential difference at the intersection between the wirings.

The materials forming the x-direction wiring 61 and the y-direction wiring 62, and the first and second electrodes 2 and 4 may be partially or entirely the same or different. May be. These materials are appropriately selected from, for example, the above-described electrode materials. When the material forming the first and second electrodes and the wiring material are the same, it can be said that the wiring connected to the electrodes is the electrode.

In the present embodiment, the electrons emitted from the electron-emitting device can be controlled by the peak value and the width of the pulse-like voltage applied between the electrodes when the electrons are below the threshold voltage. On the other hand, when the voltage is equal to or lower than the threshold voltage, almost no light is emitted.

According to this characteristic, even when a large number of electron-emitting devices are arranged, if a pulse-like voltage is appropriately applied to each of the electron-emitting devices, the electron-emitting device can be selected according to the input signal. The amount of electron emission can be controlled.

Therefore, in the above configuration, individual elements can be selected and driven independently using simple matrix wiring.

Next, an image forming apparatus using the above-described electron source will be described with reference to FIG.

In FIG. 10, reference numeral 60 denotes an electron source substrate on which a plurality of electron-emitting devices are arranged, 91 denotes a rear plate on which the electron source substrate 60 is fixed, and 96 denotes a fluorescent film 9 on the inner surface of a glass substrate 93.
4 and a face plate on which metal packs 95 and the like are formed. Reference numeral 92 denotes a support frame, and a rear plate 91 and a face plate 96 are connected to the support frame 92 using frit glass or the like.

The envelope (panel) 98 is composed of the face plate 96, the support frame 92, and the rear plate 91 as described above. Since the rear plate 91 is provided mainly for the purpose of reinforcing the strength of the electron source substrate 60, the electron source substrate 60
Separate rear plate 91 if sufficient strength by itself
May be unnecessary, and the electron source substrate 60 and the rear plate 91 may be integrally formed members.

Frit glass is applied to the bonding surface where the face plate 96 and the rear plate 91 in which the fluorescent film 94 and the metal back 95 are disposed inside are joined to the support frame 92, and the face plate 96, the support frame 92 and the rear plate are coated. 91 is fixed at a predetermined position, fixed, heated, fired and sealed.

Various heating means such as lamp heating using an infrared lamp or the like, a hot plate and the like can be adopted as the heating means for firing and garmenting, but are not limited to these.

The bonding material for heating and bonding the plurality of members constituting the envelope 98 is not limited to frit glass, but may be any bonding material that can form a sufficient vacuum atmosphere after the sealing step. Materials can be adopted.

The above-described envelope 98 is an embodiment of the present invention, and is not limited, and various types can be adopted.

As another example, the support frame 92 may be directly sealed to the electron source substrate 60, and the envelope 98 may be constituted by the face plate 96, the support frame 92, and the electron source substrate 60. Further, by providing a support (not shown) called a spacer between the face plate 96 and the rear plate 91, an envelope 98 having sufficient strength against atmospheric pressure can be formed.

FIGS. 11A and 11B are schematic views of the fluorescent film 94 formed on the face plate 96. FIG. The fluorescent film 94 can be composed of only a phosphor in the case of monochrome. In the case of the color fluorescent film 94, it is composed of a black conductive material 86 called a black stripe shown in FIG. 11A or a black matrix shown in FIG. be able to.

The purpose of providing the black stripes and the black matrix is to make the color separation between the phosphors 85 of the necessary three primary color phosphors black in the case of color display so that color mixing and the like become inconspicuous. The object of the present invention is to suppress a decrease in contrast caused by external light reflection at 94. As a material of the black stripe, a material having conductivity and low light transmission and reflection can be used in addition to a commonly used material mainly containing graphite.

As a method of applying the fluorescent film 94 on the glass substrate 93, a precipitation method, a printing method, and the like can be adopted regardless of monochrome or color.

On the electron source side of the fluorescent film 94, a metal back 95 is usually provided. The purpose of providing the metal back 95 is to improve the brightness by mirror-reflecting the light emitted from the fluorescent film 94 toward the electron source toward the face plate 96, and to act as an electrode for applying an electron beam acceleration voltage. And protecting the fluorescent film 94 from damage due to the collision of negative ions generated in the envelope 98.

The metal back 95 is formed after the fluorescent film 94 is formed.
The fluorescent film 94 can be manufactured by performing a smoothing process (usually called “filming”) on the electron source side surface of the fluorescent film 94 and then depositing Al using vacuum deposition or the like.

The face plate 96 is further provided with a fluorescent film 9.
A transparent electrode (not shown) may be provided on the outer surface side of the fluorescent film 94 in order to increase the conductivity of No. 4.

Next, the envelope (panel) subjected to the sealing step
A vacuum sealing step for sealing 98 will be described.

In the vacuum sealing step, the envelope (panel) 98 is heated and kept at 80 ° C. to 250 ° C., and exhausted through an exhaust pipe (not shown) of an exhaust device such as an ion pump and a sorption pump. Then, after the atmosphere is made sufficiently low in organic substances, the exhaust pipe is heated and melted by a burner and sealed.

In order to maintain the pressure after the envelope 98 is sealed, a getter process may be performed. This is because the getter disposed at a predetermined position (not shown) in the envelope 98 is heated by heating using resistance heating or high-frequency heating immediately before or after the envelope 98 is sealed. This is a process for forming a deposited film. The getter usually contains Ba or the like as a main component, and maintains the atmosphere in the envelope 98 by the adsorption action of the deposited film.

In the image forming apparatus constructed by using the electron sources of the simple matrix arrangement manufactured by the above steps, the external terminals Dox1 to Doxm, Dox
By applying a voltage via y1 to Doyn, electron emission occurs.

A high voltage is applied to the metal back 95 or the transparent electrode (not shown) via the high voltage terminal 97 to accelerate the electron beam. The accelerated electrons collide with the fluorescent film 94 and emit light to form an image.

FIG. 12 is a block diagram showing an example of a drive circuit for performing display according to an NTSC television signal.

This drive circuit has m switching elements inside (in the figure, S1 to Sm are schematically shown). Each switching element selects either the output voltage of the DC voltage source Vx or 0 V (ground level), and the display panel 1 as an image forming apparatus
341 is electrically connected to the external terminals Dox1 to Doxm.

Each of the switching elements S1 to Sm operates based on the control signal TSCAN output from the control circuit 1343, and can be configured by combining switching elements such as FETs.

In the case of the present embodiment, the DC voltage source Vx uses a drive voltage applied to an unscanned element based on the characteristics (electron emission threshold voltage) of the electron emission element. It is set to output a constant voltage that is equal to or lower than the voltage.

The control circuit 1343 has a function of matching the operation of each section so that appropriate display is performed based on an image signal input from the outside. The control circuit 1343 is
Synchronization signal TSY sent from synchronization signal separation circuit 1346
Based on the NC, each unit transmits TSCAN, TSFT, and TMRY control signals to each unit.

A synchronizing signal separating circuit 1346 is a circuit for separating a synchronizing signal component and a luminance signal component from an NTSC television signal input from the outside, and uses a general frequency separating circuit (filter) or the like. Can be configured.

The synchronizing signal separated by the synchronizing signal separating circuit 1346 is composed of a vertical synchronizing signal and a horizontal synchronizing signal, but is shown here as a TSYNC signal for convenience of explanation. The luminance signal component of the image separated from the television signal is referred to as a DATA signal for convenience. The DATA signal is input to the shift register 1344.

A shift register 1344 is for serially / parallel-converting the DATA signal input serially in time series for each line of an image, and is based on a control signal TSFT sent from the control circuit 1343. (Ie, the control signal TSFT can be said to be a shift clock of the shift register 1344).

The serial / parallel converted data for one line of the image (corresponding to drive data for n electron-emitting devices) is output from the shift register 1344 as n parallel signals Id1 to Idn.

The line memory 1345 is a storage device for storing data for one line of an image for a required time only, and a control signal TMRY sent from the control circuit 1343.
, The contents of Id1 to Idn are stored as appropriate.

The stored contents are Id′1 to Id′n
And output to the modulation signal generator 1347.

The modulation signal generator 1347 outputs the image data I
The signal source is a signal source for appropriately driving and modulating each of the electron-emitting devices of the present embodiment according to each of d′ 1 to Id′n, and the output signals thereof are external terminals Doy1 to Doyn.
Through the display panel 1341 to the electron-emitting devices.

As described above, the electron-emitting device of this embodiment has the following basic characteristics with respect to the emission current Ie. That is, electron emission has a clear threshold voltage Vth, and electron emission occurs only when a voltage equal to or higher than Vth is applied.

For voltages above the electron emission threshold,
The emission current also changes according to the change in the voltage applied to the electron-emitting device. From this, when a pulse-like voltage is applied to the electron-emitting device, for example, electron emission does not occur even when a voltage equal to or lower than the electron emission threshold is applied. Is output.

At this time, the intensity of the output electron beam can be controlled by changing the pulse peak value Vm. In addition, it is possible to control the total amount of charges of the output electron beam by changing the pulse width Pw.

Therefore, as a method of modulating the electron-emitting device in accordance with the input signal, a voltage modulation method, a pulse width modulation method, or the like can be employed.

When implementing the voltage modulation method, the modulation signal generator 1347 generates a voltage pulse of a fixed length and modulates the peak value of the pulse appropriately in accordance with input data. A circuit can be used.

When implementing the pulse width modulation method,
As the modulation signal generator 1347, a pulse width modulation circuit that generates a voltage pulse having a constant peak value and appropriately modulates the width of the voltage pulse according to input data can be used.

The shift register 1344 and the line memory 1
345 can be a digital signal type or an analog signal type. This is because the serial / parallel conversion and storage of the image signal may be performed at a predetermined speed.

When the digital signal type is used, it is necessary to convert the output signal DATA of the synchronization signal separation circuit 1346 into a digital signal.
An A / D converter may be provided at the output unit 6.

In this connection, the circuit used for the modulation signal generator 1347 differs slightly depending on whether the output signal of the line memory 1345 is a digital signal or an analog signal.

That is, in the case of the voltage modulation method using a digital signal, for example, a D / A conversion circuit is used as the modulation signal generator 1347. Then, an amplifier circuit and the like are added as needed.

In the case of the pulse width modulation method, the modulation signal generator 1347 includes, for example, a high-speed oscillator, a counter for counting the number of waves output from the oscillator, and a comparison between the output value of the counter and the output value of the memory. A circuit in which a comparator (comparator) is combined is used. And if necessary,
It is also possible to add an amplifier for amplifying the pulse width modulated signal output from the comparator to the drive voltage of the electron-emitting device.

In the case of the voltage modulation method using an analog signal, an amplification circuit using, for example, an operational amplifier or the like can be used as the modulation signal generator 1347. Then, a level shift circuit or the like can be added as needed.

In the case of the pulse width modulation method, for example, a voltage controlled oscillation circuit (VCO) can be used as the modulation signal generator 1347. If necessary, an amplifier for amplifying the voltage up to the drive voltage of the electron-emitting device can be added.

The configuration of the driving circuit described here is an example of an image forming apparatus to which the present invention can be applied, and various modifications can be made based on the technical idea of the present invention. The input signal is described in the NTSC system. However, the input signal is not limited to the NTSC system. In addition to the PAL and SECAM systems, a TV signal including a larger number of scanning lines (for example, MUSE system and the like) High-definition TV system) can also be adopted.

The image forming apparatus can be used not only as a display device such as a display panel, but also as an image forming device as an optical printer including a photosensitive drum or the like.

[0202]

The present invention will be described in more detail with reference to the following examples.

(Example 1) Here, a plan view and a sectional view of the electron-emitting device shown in FIGS.
The description will be made using the method for manufacturing an electron-emitting device described above.

In Example 1, an electron-emitting device in the type 1 region will be described. For this purpose, an element A having a concave structure and an element B having a convex structure are manufactured.

Hereinafter, the manufacturing process of the electron-emitting device of this embodiment will be described in detail.

(Step 1) Quartz was used for the substrate 1 and after sufficient cleaning, the first electrode 2 having a thickness of 250 was formed by sputtering.
Deposit nm Ta.

(Step 2) The insulating layer 3 having a thickness of 8
0 nm of SiO ₂ is deposited, and the second electrode 4 has a thickness of 50 nm.
Deposit nm Ta.

(Step 3) Thereafter, in a photolithography step, spin coating of a positive photoresist (AZ1500 / manufactured by Clariant), exposure and development of a photomask pattern are performed, and the mask pattern is transferred. Thereafter, the patterned photoresist is used as a mask.

(Step 4) The insulating layer 3 and the second electrode 4 are made of CF ₄
Dry etching is performed using a gas, and stopped at the first electrode 2.

Here, the element A is an element having a concave structure shown in FIG. 1, and the concave part w1 = 20 μm, the convex part w2 = 30 μm,
The pitch P1 = 50 μm and the length L1 = 50 μm for three periods.

The element B is an element having a convex structure shown in FIG. 2, and has a structure of three periods of a convex part w3 = 20 μm, a concave part w4 = 30 μm, a pitch P2 = 50 μm, and a length L1 = 50 μm.

(Step 5) Next, a 5 nm-thick Pt-Pd
A conductive film 5 was deposited on part of the structure. At this time, Pt
The length L2 where Pd was deposited was 30 μm. The Pt
The Pd conductive film was selectively deposited by an ion sputtering method using a mask using a photolithography technique.

(Step 6) The first electrode 2 and the second electrode 4
A pulse voltage of 5 V (ON time: 1 msec / OFF time: 9 msec) is applied to the Pt-Pd conductive film 5.
And a gap 6 is formed by the forming step. The forming was terminated when the resistance between the upper and lower electrodes became 10 MΩ.

(Step 7) Next, the above element was placed in a vacuum vessel, and after evacuation, BN (benzonitrile), 2.
The same pulse voltage as in the forming step was applied to the first electrode 2 and the second electrode 4 in an atmosphere of 7 × 10 ⁻⁴ Pa to generate carbon in the gap 6. This activation step was completed when the current flowing during the activation step was saturated. As a result,
The gap 6 could be formed only in the area where the Pt-Pd film was deposited. This gap width D was 6 nm.

The device fabricated as described above was evacuated again to 6.7 × 10 ⁻⁵ Pa or more in the same vacuum vessel, and kept at 150 ° C. in the vicinity of the device and heated for 3 hours or more.
Return to room temperature. At this time, the degree of vacuum is 1.3 × 10 ⁻⁶ Pa
Met.

Through the above steps, the electron-emitting devices A and B were completed.

This device is driven in a vacuum vessel. The driving voltage is Vf = 15V, the first electrode 2 has 0V, the second electrode 4
Was applied with 15V.

The anode voltage was set to Va = 10 kV, and the distance H between the electron-emitting device and the anode electrode 8 was set to 2 mm. Then, the size of the electron beam was observed using an electrode coated with a phosphor as the anode electrode 8. The electron beam size referred to here is 10% of the peak luminance of the emitted phosphor.
Up to the size of the area.

As a result, both elements A and B have the beam diameter,
The electron emission efficiency showed almost the same characteristics. The electron emission efficiency Ie / If was 1.0%.

In the present embodiment, it is possible to calculate the characteristic distance Xs = 0.95 μm obtained from the driving conditions and the like. However, in this structure, each of the concave and convex portions is 10 times or more of Xs.
Corresponds to the area of type 1 described above.

Therefore, the electron emission efficiency did not change regardless of the period of the uneven structure. The electron beam diameter in the y direction was almost the same as 280 μm, and in the x direction, non-uniform electron beams having different electron beam overlaps were observed in the elements A and B.
The electron beam became 00 μm, and the difference was almost the same.

Embodiment 2 In Embodiment 2, an electron-emitting device in the type 2 region will be described. Therefore, the element C, the element D having the concave structure and the element E having the convex structure have the same concavo-convex width.
And were produced at the same pitch.

In the element C, the concave portion w1 = 2 μm and the convex portion w2 =
The structure was 2 μm, pitch P1 = 4 μm, and length L1 = 50 μm for three periods.

In the element D, the concave portion w1 = 0.5 μm and the convex portion w
2 = 3.5 μm, pitch P1 = 4 μm, length L1 = 5
The structure has three periods of 0 μm.

In the element E, the projection w3 = 3.5 μm and the depression w
4 = 0.5 μm, pitch P2 = 4 μm, length L1 = 5
The structure has three periods of 0 μm.

The electron-emitting device of this example was manufactured by the same manufacturing process as in Example 1 except that the size of the resist mask pattern was changed.

Each of the electron-emitting devices C, D, and E was used in Example 1.
Driving was performed under the same driving conditions.

As a result, the three devices C, D, and E differed in the electron beam diameter and the electron emission efficiency.
And the element E had moderate characteristics.

The device C has an electron emission efficiency Ie / If:
0.9%, the electron beam diameter is 300 μm in the x direction,
The y direction was 280 μm.

The device D had a higher electron emission efficiency than the device C, and the electron emission efficiency Ie / If was 1.2%.
The electron beam diameter was the same as that of the element C in the y direction, and was 250 μm in the x direction.

The device E had lower electron emission efficiency than the device C, and the electron emission efficiency Ie / If was 0.8%.
The electron beam diameter was the same as that of the element C in the y direction, and was 190 μm in the x direction. Also in the present embodiment, it is possible to calculate the characteristic distance Xs = 0.95 μm obtained from the driving conditions and the like.
And is equivalent to the type 2 area described with reference to FIG.

Therefore, the electron emission efficiency and the electron beam diameter in the x direction change depending on the ratio of the concave and convex portions in the concave and convex structure. Therefore, when used as an image forming apparatus, the ratio of the periodic structure can be varied according to the specifications, and can be used as a design parameter.

(Embodiment 3) In Embodiment 3, an electron-emitting device in a type 3 region will be described.

First, an element having a concave-convex structure and a concave-convex structure having a size of 0.15 μm was manufactured, instead of a periodic structure.

The manufacturing method is the same as that of Example 2 until the film laminating method.
The following steps were devised using the same method as that described above.

As the concave structure, a method of shaving the concave portion by the FIB method was used. Further, for the protruding portion, a mask having a mask width of 0.5 μm was produced by the method of the photolithography process of Example 2,
The width was further narrowed using side etching during etching.

When this device was driven under the same conditions as in Example 2, the device in the concave portion had an electron emission efficiency of 1.5%, an electron beam diameter of 300 μm in the x direction, and 280 μm in the y direction. Did not confirm the emission of electrons.

The characteristic distance Xs = 0.
Although it can be calculated as 95 μm, in the present structure, the size of the concave and convex portions is 0.15 μm, which is about ４ of Xs. Therefore, it corresponds to the region of type 3 described with reference to FIG. 7, and almost no electrons are emitted in the convex structure.

Further, a periodic concavo-convex structure of this size was manufactured.

The FIB method was used, and w1 = 0.
15 μm, w2 = 0.15 μm, pitch P1 = 0.3 μ
m, a device having 10 periods was produced.

Then, the same driving as in the second embodiment was performed.

In this case, the electron emission efficiency Ie / If is
1.2%.

In this region, electrons were not emitted by a single convex structure. However, it was found that by forming a periodic structure, the size of the convex width was small and the adjacent concave width was short, so that electrons could be emitted. However, the electron beam diameter is 31 in the x direction.
It was as wide as 0 μm and 280 μm in the y direction.

As described above, in the electron-emitting device according to the present invention, by forming a periodic structure, a device having a desired periodic uneven structure from a small size to a large size can be formed relatively easily. It can be seen that a desired electron-emitting device can be manufactured.

Further, in the following embodiment, an embodiment which utilizes these size effects for each region and is effective for further improving the electron emission efficiency and reducing the electron beam diameter will be described.

(Embodiment 4) Embodiment 4 includes Embodiment 2 described above.
An element that efficiently converges an electron beam by using elements of type 2 and type 3, that is, elements 2 and 3 will be described.

FIG. 13 shows an example of the present structure. In this structure, the end of the periodic structure is formed by the first electrode 2.

As the concave-convex structure, similarly to the element D of Example 2, the concave portion w1 = 0.5 μm, the convex portion w2 = 3.5 μm,
The pitch P1 was 4 μm, the length L1 was 50 μm, and the cycle was four.

When the device was driven, the electron emission efficiency Ie / If was 1.0%, and the electron beam diameter in the x direction was 220 μm. This is because both ends of the period are terminated by the first electrode 2, and the spread of the electron beam is suppressed by the convergence effect sandwiched between the low potentials.

Example 5 Next, an example in which the electron-emitting devices according to the present invention are arranged in a matrix will be described. As the electron-emitting device, the device shown in FIG. 13 of the fourth embodiment is used. The image forming apparatus using the wiring diagram of the electron source and the arrangement of the electron sources uses FIGS. 8 to 10 used in the embodiment.

In FIG. 13, the fabrication of the electron-emitting device is the same as that of the fourth embodiment. As shown in FIG. 8, when the elements are arranged in a matrix, the x-directional wiring 61 also serves as the first electrode 2, but the second electrode 4 is connected to the y-directional wiring 62. In order to reduce the capacitance at the intersection of the x-direction wiring 61 and the y-direction wiring 62, the y-direction wiring 62
Is selectively laminated with a thick insulating layer 63 of 1 μm.

However, since the y-direction wiring 62 has the same potential as the second electrode 4, that is, a high potential,
When the low potential portion for convergence is to be formed by exposing the first electrode 2 or the x-direction wiring 61, the length of w6 shown in FIG. 13 is important. The length of w6 is desirably a distance that is not affected by the potential due to the uneven structure in the above discussion, that is, 10 times or more of the characteristic distance Xs determined under the above-described driving conditions. .

As a result, an image forming apparatus having a matrix arrangement as shown in FIG. 10 was constructed with electron-emitting devices having the same element characteristics as those of the fourth embodiment.

(Embodiment 6) An embodiment in which the electron beam diameter is further reduced than in Embodiment 4 will be described.

FIG. 14 is a diagram of the sixth embodiment. In this structure, the conductive film 5 is selectively formed so that the gap 6 is formed only in the central portion of the periodic structure.

As for the concave-convex structure, similarly to the element D of Example 2, the concave portion w1 = 0.5 μm, the convex portion w2 = 3.5 μm,
The pitch P1 was 4 μm, the length L1 was 50 μm, and the period was four.

The conductive film 5 was selectively formed in two cycles at the center.

When the device was driven, the electron emission efficiency Ie / If was 1.2% and the electron beam diameter in the x direction was 200 μm. This is because both ends of the cycle are terminated by the first electrode 2, and the effect of the fourth embodiment that the spread of the electron beam is suppressed by the convergence action of the low potential works more effectively. .

That is, in the fourth embodiment, the electrons having the largest spread in the x direction are the electrons emitted from the electron emission portions on the side surfaces of the last stage at both ends. Eliminating the electron emission at this portion suppresses the spread.

In this embodiment, shortening the period is effective for improving the efficiency due to the size effect. Also,
Not only eliminating the electron emission portion on the side surface of the last stage at both ends but also limiting the electron emission portion to the very center portion has the effect of improving both the efficiency of electron emission and the convergence of the electron beam. is there.

(Embodiment 7) Next, in the area of type 3,
A case where an electron-emitting device having a high electron emission density is obtained will be described.

FIG. 15 shows the seventh embodiment.

As in the case of the device of Example 3, the concave and convex portions have w1, w2 = 0.15 μm, pitch P1 = 0.3 μm, length L1 = 5 μm, and a period of 1
0 period was set.

In this embodiment, the length L2 in the y direction is 30 μm by limiting the range of the conductive film 5 to 5 μm in the y direction.
m, the electron beam diameter in the y direction can be made smaller than in the other examples.

In a normal configuration, when the size in the y direction is reduced, the emission area is reduced, so that the amount of emission from one element is reduced. (Electron emission portions) can be increased.

In the case of this embodiment, there are 20 lines of electron emitting portions for 10 periods, and a total of 100 μm emitting lines can be secured. Therefore, even if the y direction is limited, the same amount of electron emission as in the other embodiments can be ensured, and the design can be made so as not to reduce the amount of electron emission.

That is, according to this structure, an element having a high electron emission density can be obtained, and the shape of the electron beam in one pixel in the x-direction and the y-direction can be made desired.

Another advantage of the present embodiment is that FIG.
Normally, as shown in FIG. 5, the electron beam tends to have a point with a high probability of arrival on the x-axis. However, by adopting the structure of this embodiment, the distribution is not concentrated at one point in the x-direction, and the distribution is broadened. Thus, an image forming apparatus which is hardly damaged by the phosphor can be formed.

(Embodiment 8) Next, in the area of type2,
An embodiment for obtaining an element having a small electron beam diameter will be described.

FIG. 16 shows the eighth embodiment.

In this region, an embodiment utilizing the fact that an electron emission portion can be selectively formed on one of the side surfaces by the uneven portion if the size of the uneven structure is large to some extent.

The concave-convex structure is a convex structure, and w3 = 1 μm
m, w4 = P3 = 90 μm. The conductive films 5 were selectively formed on the outside of each, and the gaps 6 were formed.

In the type 2 region, the arrival position of the electron beam is close in both the concave structure and the convex structure. Also,
When the pitch is adjusted according to the reach distance, the electron beam position can be adjusted at a relatively small pitch.

Therefore, the electron emission amount can be doubled without increasing the size of one pixel.

Also, in the case of the concave structure, in which the gap 6 is provided on the inner side surface, the same effect can be obtained although the pitch slightly increases.

As described above, the uneven structure and the type
By providing two electron-emitting portions at different pitches in the element in the region e2, it is possible to converge the electron beam at one point and increase the amount of electron emission.

[0277]

As described above, according to the present invention, an uneven structure is provided by arranging a plurality of convex portions in which a second electrode is laminated on a first electrode with an insulating layer interposed therebetween. By changing the potential distribution near the gap by changing the width of the gap, by setting the state of the electric field and setting the electron emission characteristics of the electrons emitted from the gap, the width of the concave and convex portions is reduced. The modulation structure of the potential by the change can be easily manufactured at a high density, and it becomes possible to manufacture an electron-emitting device having a desired setting so as to exert effects on both the efficiency of electron emission and the convergence of the diameter of the emitted electron beam. .

By using the electron-emitting device according to the present invention, it is possible to form an image forming apparatus having a high focus rate by converging the electron beam diameter, or to improve the electron emission rate to achieve an image forming apparatus having high power consumption. Or an image forming apparatus with reduced deterioration of a phosphor that emits light due to emitted electrons and an excellent durability can be formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view and a plan view illustrating an electron-emitting device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view and a plan view showing an electron-emitting device according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a driving state of the electron-emitting device according to the embodiment of the present invention.

FIG. 4 is a process chart showing an example of a method for manufacturing an electron-emitting device according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view of the electron-emitting device and a diagram for explaining an electron beam for explaining a high-efficiency operation of the electron-emitting device according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram illustrating an operation of the electron-emitting device according to the embodiment of the present invention.

FIG. 7 is a graph illustrating an operation of the electron-emitting device according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of an electron source in which electron-emitting devices manufactured according to the present invention are connected and arranged in a matrix.

FIG. 9 is a wiring diagram showing an example of an electron source in a simple matrix arrangement using the electron-emitting devices according to the embodiment of the present invention.

FIG. 10 is an external perspective view illustrating an example of an image display device according to an embodiment of the present invention.

FIG. 11 is a diagram showing a fluorescent film used in the image display device according to the embodiment of the present invention.

FIG. 12 is a block diagram illustrating an example of a driving circuit for performing display according to a television signal on the image display device according to the embodiment of the present invention.

FIG. 13 is a plan view and a sectional view showing an electron-emitting device according to Example 4 of the present invention.

FIG. 14 is a plan view and a cross-sectional view illustrating an electron-emitting device according to a sixth embodiment of the present invention.

FIG. 15 is a plan view showing an electron-emitting device according to Example 7 of the present invention.

FIG. 16 is a schematic diagram showing a driving state of an electron-emitting device according to Example 8 of the present invention.

FIG. 17 is a cross-sectional view and a plan view showing a conventional electron-emitting device.

FIG. 18 is an explanatory diagram showing a potential distribution and an electron beam trajectory of a conventional electron-emitting device.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 first electrode 3, 63 insulating layer 4 second electrode 5 conductive film 6 gap 8 anode electrode 9, 10 power supply 21 resist pattern 60 electron source substrate 61 x-direction wiring 62 y-direction wiring 85 phosphor 86 black conductive material 91 rear plate 92 support frame 93 glass substrate 94 fluorescent film 95 metal back 96 face plate 97 high voltage terminal 98 envelope

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takeo Tsukamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 5C036 EF01 EF06 EF08 EG02 EG12

Claims (17)

[Claims] A first electrode having a low potential provided on the substrate; a second electrode having a high potential provided at a position further away from the substrate than the first electrode; and the first electrode and the second electrode. Electrically connected between the electrodes,
A conductive film having a gap from which electrons are partially emitted, comprising: a plurality of protrusions in which the second electrode is stacked on the first electrode via an insulating layer; A structure is provided, and by changing the potential arrangement near the gap by changing the width of the concave and convex portions of the concave-convex structure, the state of the electric field is defined, and the electron emission of electrons emitted from the gap is defined. An electron-emitting device having characteristics set. 2. The electron-emitting device according to claim 1, wherein said concave-convex structure is a periodic structure in which a concave portion and a convex portion are continuously provided periodically. 3. An anode electrode disposed at a distance H from the first electrode, wherein an anode voltage Va is applied to the anode electrode and a drive voltage Vf is applied between the first electrode and the second electrode. In this case, when the characteristic distance Xs = (H · Vf) / (π · Va), the distance from the gap to the second electrode is less than 200 times the gap width or equal to or less than the characteristic distance Xs. The electron-emitting device according to claim 1 or 2, wherein 4. An anode electrode disposed at a distance H from the first electrode, wherein an anode voltage Va is applied to the anode electrode and a drive voltage Vf is applied between the first electrode and the second electrode. In this case, when the characteristic distance Xs = (H · Vf) / (π · Va), the width of the concave portion and the convex portion is set to be smaller than 10 times the characteristic distance Xs, and the ratio of the width of the concave portion to the width of the convex portion is set. The electron-emitting device according to claim 1, wherein the number is one or less. 5. The electron-emitting device according to claim 1, wherein both ends of the concave-convex structure are terminated by first electrodes that are concave portions. 6. An anode electrode disposed at a distance H from the first electrode, wherein an anode voltage Va is applied to the anode electrode, and a drive voltage Vf is applied between the first electrode and the second electrode. In this case, assuming that the characteristic distance Xs = (H · Vf) / (π · Va), the width of the first electrode that terminates both ends of the concavo-convex structure is provided over 10 times the characteristic distance Xs. The electron-emitting device according to claim 5, wherein: 7. The electron-emitting device according to claim 1, wherein the gap of the conductive film is provided only in a central region of the concavo-convex structure. 8. An anode electrode provided at a distance H from the first electrode, wherein an anode voltage Va is applied to the anode electrode and a drive voltage Vf is applied between the first electrode and the second electrode. In this case, when the characteristic distance Xs = (H · Vf) / (π · Va), the width of the concave portion and the convex portion is provided to be smaller than ４ of the characteristic distance Xs, and the width of the concave portion and the width of the convex portion The electron-emitting device according to claim 1, wherein the ratio is set to 1 or less. 9. An anode electrode to which electrons emitted from an electron-emitting device reach, wherein two projections are provided in the uneven structure, and the conductive film is provided on both side walls of the uneven structure among the side walls of the projection. The gap of a film is provided, and the two gaps provided are spaced apart such that electrons emitted from the gap at the anode electrode reach substantially one point. 3. The electron-emitting device according to item 2. 10. An electron source, wherein a plurality of the electron-emitting devices according to claim 1 are arranged on a substrate. 11. An electron source comprising a plurality of the electron-emitting devices according to claim 1 arranged in a matrix. 12. A first electrode, an insulating layer formed on the first electrode, a second electrode formed on the insulating layer, and connected to the first electrode and arranged on the insulating layer. The first
A laminate comprising: a conductive film; and a second conductive film connected to the second electrode and disposed on the insulating layer and opposed to the first conductive film with a gap therebetween. An electron source, comprising: a plurality of stacked bodies, wherein the plurality of stacked bodies are arranged so as to be disposed on the first electrode, the plurality of stacked bodies including a voltage application unit configured to apply a voltage higher than a voltage applied to the first electrode to a second electrode. An electron source, which is disposed on the substrate with a gap therebetween, wherein the second conductive films constituting each of the adjacent stacked bodies are connected to each other. 13. The electron source according to claim 12, wherein said second conductive films are connected on said substrate. 14. A first electrode, an insulating layer formed on the first electrode, a second electrode formed on the insulating layer, connected to the first electrode, and disposed on the insulating layer. The first
A laminate comprising: a conductive film; and a second conductive film connected to the second electrode and disposed on the insulating layer and opposed to the first conductive film with a gap therebetween. An electron source, comprising: a plurality of stacked bodies, wherein the plurality of stacked bodies are arranged so as to be disposed on the first electrode, the plurality of stacked bodies including a voltage application unit configured to apply a voltage higher than a voltage applied to the first electrode to a second electrode. An electron source, wherein the electron source is disposed on the substrate with a gap therebetween, and the interval between the adjacent stacked bodies is different from the width of the second electrode in the interval direction. 15. An image forming apparatus comprising: the electron-emitting device according to claim 1; and an image forming member. 16. An image forming apparatus according to claim 15, further comprising a driving device for controlling an electron beam composed of electrons emitted from said electron-emitting device in accordance with an information signal. 17. An image forming apparatus having an electron source and an image forming member, wherein the electron source is the electron source according to claim 12.