JP2000123763A - Image forming device using electron emitting element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cover a high-conductivity material in the normal line direction of the luminescent spot center of a base point by selectively covering the surface of an insulating substrate on an electron source substrate with a material having the conductivity higher than that of a substrate material, and keeping the high- conductivity material in contact with at least one of element electrodes and wires. SOLUTION: A substrate 1 made of quartz glass is fully washed, an element electrode material is stacked on it, then element electrodes 2, 3 are formed on the substrate 1, and an organic metal solution is applied on them to form an organic metal thin film. The organic metal thin film is heated and baked to form a conductive thin film 4, then a film of a high-conductivity material is formed. The film of the high-conductivity material is formed on the surface of an insulating substrate, and part of it is kept in contact with at least wires or the element electrodes 2, 3. When the covering state of the high-conductivity material is properly determined according to the position of the substrate 1 and a luminescent spot, the power consumption is suppressed, and the orbit of an electron beam can be made very stable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as an image display apparatus using an electron source having a large number of surface conduction electron-emitting devices, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, two types of electron-emitting devices using a thermionic electron-emitting device and a cold-cathode electron-emitting device have been known. In particular, cold-cathode electron-emitting devices include a field emission type (hereinafter, referred to as an “FE type”),
There are an insulating layer / metal type (hereinafter, referred to as “MIM type”) and a surface conduction electron-emitting device.

[0003] As an example of the FE type, W. P. Dyke
& W. W. Dolan, "Field emissi
on ", Advance in Electron P
physics, 8, 89 (1956) or C.I. A.
Spindt, “PHYSICAL Propertyi
es of thin-film field emi
session cathodes with mollyb
denium cones ", J. Appl. Phys.
s. , 47, 5248 (1976).

As an example of the MIM type, C.I. A. M
ead “Operation of Tunnel-Em
issue Devices ", J. Apply. P.
hys. , 32, 646 (1961).

Further, as an example of the surface conduction type electron-emitting device type, M.S. I. Elinson, Recio Eng.
Electron Phys. , 10, 1290, (1
965).

[0006] The surface conduction electron-emitting device utilizes the phenomenon that electron emission occurs when a current flows 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 by Elinson and the like and a device using an Au thin film [G. Dittmer: "Thin SolidFi
lms ", 9,317 (1972)] , In 2 O 3 / S
nO ₂ thin film [M. Hartwell and
C. G. FIG. Fonstad: "IEEE Trans.
ED Conf. "519 (1975)], using a carbon thin film [Hisashi Araki et al .: Vacuum, Vol. 26, No. 1,
22 (1983)].

As a typical example of these surface conduction electron-emitting devices, the above-mentioned M.P. Figure 1 shows the device configuration of Hartwell
Is shown schematically in FIG. In FIG. 1, reference numeral 1 denotes a substrate,
Reference numeral 4 denotes a conductive thin film, which is formed of a metal oxide thin film or the like formed by sputtering in an H-shaped pattern, and the electron emission portion 5 is formed by an energization process called energization forming described later. Note that the element electrode interval L in the figure is 0.5 to 1
mm and W are set to 0.1 mm.

Conventionally, in these surface conduction electron-emitting devices, an electron-emitting portion 5 is formed by performing an energization process called energization forming on the conductive thin film 4 before performing electron emission. Was common. That is, the energization forming means a DC voltage or a very slowly increasing voltage, for example, 1 V /
This means that the conductive thin film is locally destroyed, deformed or deteriorated by applying a current for about a minute to form the electron emitting portion 5 in an electrically high resistance state. Note that the electron-emitting portion 5 is a part of the conductive thin film 4 in which a crack has occurred, and emits electrons from the vicinity of the crack. The surface conduction type electron-emitting device that has been subjected to such an energization forming process is one in which a voltage is applied to the above-described conductive thin film 4 and a current is caused to flow through the device to cause the electron-emitting portion 5 to emit electrons.

The above-mentioned surface conduction electron-emitting device has a simple structure and is easy to manufacture.
There is an advantage that a large number of elements can be arranged and formed. Therefore, various applications that can take advantage of this feature are being studied. For example, there are a charged beam source and a display device. In particular, in an image forming apparatus such as an image display apparatus, a flat panel display apparatus using a liquid crystal has been widely used in place of a CRT in recent years. However, since it is not a self-luminous type, it is necessary to have a backlight. Therefore, development of a self-luminous display device has been desired. In this regard, a self-luminous display device is a combination of the above-described electron source having a large number of surface conduction electron-emitting devices and a phosphor that emits visible light by electrons emitted from the electron source. An image forming apparatus which is an image display apparatus is advantageous (see, for example, US Pat. No. 5,066,883).

FIG. 8 is a basic configuration diagram of an image forming apparatus using a surface conduction electron-emitting device. 8, reference numeral 21 denotes an electron source substrate on which an electron-emitting device is formed, 31 denotes a rear plate to which the electron source substrate 21 is fixed, and 36 denotes a face in which a fluorescent film 34 and a metal back 35 are formed on the inner surface of a glass substrate 33. Reference numeral 32 denotes a support frame, and the rear plate and the face plate constitute an envelope 37 at a distance H. In FIG. 8,
Reference numeral 24 corresponds to the electron-emitting portion in FIG. 1, and reference numerals 22 and 23 are X-direction wiring and Y-direction wiring connected to a pair of device electrodes of the surface conduction electron-emitting device.

In the above-described image forming apparatus, when an acceleration voltage Va is applied to the metal back 35 and a predetermined voltage Vf is applied between the electrodes 2 and 3 at the same time, an electron beam is emitted from the electron emission portion 24 and the phosphor target Emits light.

[0012]

However, in the case of an image forming apparatus using a surface conduction electron-emitting device, the trajectory of the electron beam is not always stable, and the shape of the luminescent spot of the phosphor changes. The quality of the displayed image deteriorates, which is inconvenient. This is because the potential of the insulating substrate 1 provided with the surface conduction electron-emitting device is unstable, and the electron beam is affected by the unstable potential.

Although the cause of the potential instability is still unknown, it is caused by charging by electrons emitted from the surface conduction electron-emitting device, or generated by members constituting the surface conduction electron-emitting device. It is considered that the charge is caused by ions. to solve this problem,
On the insulating substrate surface around the electron-emitting device, a potential regulating means for regulating the surface potential is provided to stabilize the potential of the substrate surface,
A method for stabilizing the trajectory of an electron beam has already been proposed (see Japanese Patent Application Laid-Open No. 1-283735).

However, in the case of an image forming apparatus using an electron source substrate on which a large number of surface conduction electron-emitting devices are arranged, insulation between wirings is maintained, or positional accuracy in manufacturing technology is increased by forming the wiring in a large area. From the limit, it was practically difficult to provide the potential regulating means on the entire insulating surface. For this reason, exposure of the insulating surface on the electron source substrate is unavoidable, and the trajectory of the electron beam may become unstable.

When the face plate is irradiated with electrons, the positively ionized molecules are released and ionized by the impurity molecules adsorbed on the face plate. From the normal direction. It has been observed that the positive ions charge the insulating surface on the electron source substrate. This charge amount is extremely large on the insulating surface in the direction normal to the electron irradiation position of the face plate, and rapidly decreases depending on the distance from this position. If the bright spot on the face plate due to the electron irradiation is located near the normal direction of the electron emitting portion, the electron source substrate in the normal direction is covered with a conductive material such as an electrode or a thin film for forming the electron emitting portion. Therefore, charging of the electron source substrate is suppressed.

However, in the surface conduction electron-emitting device, the electric field generated by the potential accelerating power supply Va is distorted by the electric field generated by the device driving power supply Vf. Not formed in the line direction. Therefore, if the position of the luminescent spot due to electron irradiation is located in the normal direction of the insulating surface of the electron source substrate, the charging of the insulating surface becomes remarkable, and the trajectory of the electron beam becomes unstable. Particularly, in a thin image forming apparatus, since the distance H between the face plate and the electron source substrate is extremely close, the potential rise due to charging is remarkable, and in the worst case, the element is deteriorated by the discharge.

In order to solve this problem, a method of coating the surface of an insulating substrate around an electron-emitting device with a material having a higher conductivity than the substrate material, stabilizing the potential on the substrate surface, and stabilizing the trajectory of the electron beam. (Japanese Patent Laid-Open No. 1-29)
No. 8624). However, when coating with a high-conductivity material, the position of the bright spot on the face plate is not taken into consideration, so that a coating with a high-conductivity material should be formed more than necessary to obtain a sufficient antistatic effect. Had been done. For this reason, there has been a problem that an unnecessary current flows between the device electrodes, thereby increasing power consumption.

The present invention has been made based on the above circumstances, and the object is to pay attention to the fact that the position of a luminescent spot on a face plate by electron irradiation is determined by Va, Vf, and H. In the normal direction of the luminance center of the base point,
An object of the present invention is to provide an image forming apparatus coated with a material having high conductivity and a method for manufacturing the same.

[0019]

Therefore, in the present invention,
An X-direction wiring and a Y-direction wiring stacked on an insulating substrate via an interlayer insulating layer, and a plurality of surface conduction electron-emitting devices having a thin film including an electron-emitting portion between a pair of device electrodes, An electron source substrate in which the device electrodes of the plurality of surface conduction electron-emitting devices are connected to the X-direction wiring and the Y-direction wiring to be arranged in a matrix; and each of the surface conduction electron-emitting devices. And a face plate having a phosphor target facing to receive the electron beam irradiation from the image forming apparatus, in the normal direction of the brightness center of the bright spot by the electron beam irradiation on the phosphor target, The insulating substrate surface on the electron source substrate is selectively coated with a material having higher conductivity than the substrate material, and the high conductivity material is at least one of the device electrode and the wiring. Characterized in that it is coated with the contact person.

[0020]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic view showing a configuration of a surface conduction electron-emitting device to which the present invention can be applied. FIG. 1 (a) is a plan view and FIG. 1 (b) is a cross-sectional view.
In FIG. 1, reference numeral 1 denotes a substrate, 2 and 3 denote device electrodes, 4 denotes a conductive thin film, and 5 denotes an electron emitting portion. The substrate 1 is made of quartz glass, glass having a reduced impurity content such as Na, blue plate glass, a glass substrate formed by laminating SiO ₂ on a blue plate glass by sputtering, ceramics such as alumina, and Si. A substrate or the like can be used.

The material of the opposing device electrodes 2 and 3 is
In this case, a general conductor material can be used. this
Is, for example, Ni, Cr, Au, Mo, W, Pt, T
metals such as i, Al, Cu, Pd or alloys thereof, and
And Pd, Ag, Au, RuO _Two, Pd-Ag, etc.
Consists of metal or its metal oxide and glass
Printed conductor, In_TwoO_Three-SnO_TwoSuch as transparent conductors
And semiconductor materials such as polysilicon.
Can be

The element electrode interval L, the element electrode length W, the shape of the conductive thin film 4, and the like are designed in consideration of the form to be applied. The element electrode interval L can be preferably in the range of several hundred nm to several hundred μm, more preferably,
It can be in the range of several μm to several tens μm.

The length W of the device electrode can be in the range of several μm to several hundred μm in consideration of the resistance value of the electrode and the electron emission characteristics. The film thickness d of the device electrodes 2 and 3 is several tens n.
m to several μm. In addition, not only the configuration shown in FIG. 1 but also a configuration in which the conductive thin film 4 and the opposing element electrodes 2 and 3 are laminated on the substrate 1 in this order.

As the conductive thin film 4, a fine particle film composed of fine particles is preferably used in order to obtain good electron emission characteristics. The film thickness is appropriately set in consideration of the step coverage to the device electrodes 2 and 3, the resistance value between the device electrodes 2 and 3, the forming conditions described later, and the like.
Usually, it is preferably in the range of several times 0.1 nm to several hundred nm, more preferably in the range of 1 nm to 50 nm. The resistance value of Rs is 102 to 1
It is a value of 07Ω / □. Rs has a thickness t and a width w.
This is the amount that appears when the resistance R of the thin film having a length of 1 is R = Rs (l / w). Here, the forming process has been described using the energizing process as an example, but the forming process is not limited to this.
It includes a process for forming a high resistance state by causing a crack in the film.

The material constituting the conductive thin film 4 is Pd, P
t, Ru, Ag, Au, Ti, In, Cu, Cr, F
e, Zn, Sn, Ta, W, Pd and other metals, PdO,
SnO_Two, In_TwoO_Three, PbO, Sb_TwoO_ThreeSuch as oxidation
Object, HfB_Two, ZrB_Two, LaB ₆, CeB₆, Y
B_Four, GdB_FourBoride such as TiC, ZrC, Hf
Carbides such as C, Ta, C, SiC, WC, TiN, Z
nitrides such as rN and HfN, semiconductors such as Si and Ge,
It is appropriately selected from carbon and the like.

The fine particle film described here is a film in which a plurality of fine particles are aggregated, and has a fine structure in a state where the fine particles are individually dispersed and arranged, or in a state where the fine particles are adjacent to each other or overlap each other (some fine particles). Gather together to form an island-like structure as a whole). The particle size of the fine particles is from several times 0.1 nm to several hundred nm.
, Preferably in the range of 1 nm to 20 nm.

Here, since the word "fine particles" is frequently used, its meaning will be described. That is, small particles are called “fine particles”, and smaller ones are called “ultra fine particles”. In general, it is widely known that a particle having a size smaller than that of the “ultra-fine particles” and having a number of atoms of about several hundreds or less is referred to as a “cluster”.

However, each boundary is not strict, and differs depending on what kind of property is focused on. Also, “fine particles” and “ultra fine particles”
May be collectively referred to as “fine particles”, and the description herein is in line with this. This is described in detail in "Experimental Physics Course 14: Surfaces and Particles" (edited by Yoshio Kinoshita, published by Kyoritsu Shuppan, September 1, 1986). In other words, "the term" fine particles "used herein means a diameter of about 2 to 3 μm to about 10 nm, and especially the term" ultrafine particles "means a particle size of about 10 nm to about 2 to 3 nm. Since both are collectively written as particles, they are not exact and are only a rough guide.If the number of atoms constituting a particle is from 2 to several tens to several hundreds, It is referred to as a cluster. "(Pages 195 to 226).

In addition, in the definition of "ultra-fine particles" in the "Hayashi-Ultra-fine Particle Project" of the New Technology Development Corporation, the lower limit of the particle size is specified to be smaller, as follows. That is, in the “Ultrafine Particle Project” of the Creative Science and Technology Promotion System (1981 to 1986), particles having a size (diameter) in the range of about 1 to 100 nm are referred to as “ultrafine particles”.
e). Then, one ultrafine particle is an aggregate of about 100 to 108 atoms. In terms of atomic scale, ultrafine particles are large to giant particles. ("Ultra Fine Particles-Creative Science and Technology-" Hayashi Tax, Ryoji Ueda, Akira Tazaki, ed., Mita Publishing, 1988, page 2
(4th line) “A particle smaller than ultrafine particles, that is, a single particle composed of several to several hundred atoms is usually called a cluster” (p. 2, lines 12 to 13 of the same book).
It is described.

[0030] Based on the above general name,
In this specification, the term "fine particles" refers to an aggregate of a large number of atoms and molecules, and the lower limit of the particle size is from several times 0.1 nm to about 1 nm, and the upper limit is about several μm.

The electron-emitting portion 5 is constituted by a high-resistance crack formed in a part of the conductive thin film 4 and is formed by a method such as a film thickness, a film quality and a material of the conductive thin film 4 and a later-described energization forming. Depends. In some cases, conductive fine particles having a particle diameter in the range of several times 0.1 nm to several tens of nm are present inside the electron-emitting portion 5. The conductive fine particles contain some or all of the elements of the material constituting the conductive thin film 4. The electron emitting portion 5 and the conductive thin film 4 in the vicinity thereof can also contain carbon and a carbon compound.

The coating of a highly conductive material is a coating of a material having a higher conductivity than the insulating surface. Here, the film does not necessarily mean a state in which the entire surface is covered, but also a state in which fine particles of a high-conductivity material are dispersed and arranged at appropriate intervals. In this case, by appropriately selecting the particle size and density of the fine particles, the sheet resistance on the substrate surface can be controlled to an appropriate value. Note that the sheet resistance Rs
Represents the resistance R of a thin film having a thickness t, a width w, and a length l,
This is the amount that appears when R = Rs (l / w).

The material of the fine particles used here is very wide.
Range, for example, Au, Pt, Ag, Cu, W,
Metals such as Ni, Mo, Ti, Ta, Cr, or S
nO _Two, Metal oxides such as ITO, or carbides,
Even higher conductivity than insulating substrate material, such as carbon
A material having a ratio can be used.

There are various methods for manufacturing the above-mentioned surface conduction electron-emitting device. One example is schematically shown in FIG. In FIG. 2, the same parts as those shown in FIG. 1 are denoted by the same reference numerals.

1) The substrate 1 is sufficiently washed with a detergent, pure water, an organic solvent, and the like, and after the element electrode material is deposited by a vacuum evaporation method, a sputtering method, or the like, for example, by using a photolithography technique, Device electrodes 2 and 3 are provided on a substrate 1.
(See FIG. 2A).

2) An organic metal solution is applied to the substrate 1 provided with the device electrodes 2 and 3 to form an organic metal thin film. As the organic metal solution, a solution of an organic metal compound containing the metal of the material of the conductive film 4 as a main element can be used. Then, the organic metal thin film is heated and baked, and is patterned by lift-off, etching, or the like to form a conductive thin film 4 (see FIG. 2B). Here, the method of applying the organometallic solution has been described, but the method of forming the conductive thin film 4 is not limited thereto, but may be a vacuum deposition method, a sputtering method, a chemical vapor deposition method, a dispersion method, or the like. A coating method, a dipping method, a spinner method, or the like can also be used.

3) Next, a film of a high conductivity material is formed. The same effect can be obtained even if this step is performed before the formation of the thin film 4 for forming electron emission in 2). Examples of the coating method include a vacuum deposition method, a sputtering method, a chemical vapor deposition method, and a dispersion coating method. In order to perform coating in the present invention, it is desirable that the resistance value can be controlled with the same positional accuracy as the pattern of the electron source substrate. Therefore, for example, the formation method using an inkjet ejecting apparatus is considered to be a simple and effective one. On this occasion,
The highly conductive material needs to be in a state where droplets can be formed, that is, in a state of being dispersed or dissolved in water or a solvent. For example, a liquid obtained by adding fine particles of a highly conductive material and an additive for promoting the dispersion of the fine particles to an organic solvent such as an alcohol and adjusting the dispersion state of the fine particles by stirring or the like can be used. At this time, the state of the coating of the high conductivity material can be controlled by the components of the droplet, the concentration, the number of times of application, the application pattern, and the like.

4) Subsequently, a forming process is performed. As an example of a method of the forming process, a method by an energization process will be described. When a current is applied between the device electrodes 2 and 3 using a power supply (not shown), an electron-emitting portion 5 having a changed structure is formed at a portion of the conductive thin film 4 (FIG. 2C).
See). According to the energization forming, a portion of the conductive thin film 4 having a locally changed structure such as destruction, deformation or alteration is formed. This portion constitutes the electron emission portion 5.

FIG. 3 shows an example of the voltage waveform of the energization forming. The voltage waveform is preferably a pulse waveform. For this purpose, a method shown in FIG. 3A in which a pulse with a constant pulse peak value is applied continuously and a method shown in FIG. 3B in which a voltage pulse is applied while increasing the pulse peak value are used. There are the methods shown.

T1 and T2 in FIG.
The pulse width and pulse interval of the voltage waveform. Normally T1 is 1
μsec to 10 msec, and T2 is 10 μs
ec is set in the range of 10 msec. The peak value of the triangular wave (peak voltage at the time of energization forming) is appropriately selected according to the form of the surface conduction electron-emitting device. Under such conditions, for example, a voltage is applied for several seconds to several tens minutes. Note that the pulse waveform is not limited to a triangular wave, and a desired waveform such as a rectangular wave can be adopted. T1 and T2 in FIG. 3B can be the same as those shown in FIG. 3A. The peak value of the triangular wave (peak voltage at the time of energization forming) is, for example, 0.
It can be increased by about 1 V step.

The end of the energization forming process can be detected by applying a voltage that does not locally destroy or deform the conductive thin film 2 during the pulse interval T2, and measuring the current. For example, an element current flowing by applying a voltage of about 0.1 V is measured, and a resistance value is obtained. When the resistance shows 1 MΩ or more, the energization forming is terminated.

5) It is preferable to perform a process called an activation process on the element after the forming. The activation process means that the device current If and the emission current Ie are
This is a step that changes significantly (to be described later, see FIG. 4). The activation treatment can be performed, for example, by repeatedly applying a pulse under an atmosphere containing a gas of an organic substance, similarly to the energization forming. This atmosphere is
For example, when the inside of a vacuum vessel is evacuated using an oil diffusion pump or a rotary pump, the organic gas can be formed using the organic gas remaining in the atmosphere, and once sufficiently evacuated by an ion pump or the like. It can also be obtained by introducing a gas of an appropriate organic substance into a vacuum.

The preferable gas pressure of the organic substance at this time varies depending on the above-described application form, 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 organic acids such as alkanes, alkenes, aliphatic hydrocarbons of alkynes, aromatic hydrocarbons, alcohols, aldehydes, ketones, amines, phenols, carboxylic acids and sulfonic acids. And specifically, C such as methane, ethane, and propane
saturated hydrocarbons represented by _n H _{2n + 2} , 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, or a mixture thereof can be used.

By this treatment, carbon or a carbon compound is deposited on the device from organic substances present in the atmosphere,
As described above, the element current If and the emission current Ie significantly change. The end of the activation process is appropriately determined while measuring the element current If and the emission current Ie. Here, the pulse width, pulse interval, pulse crest value, and the like are set as appropriate.

Carbon and carbon compounds include, for example, graphite (including so-called HOPG ', PG, and GC;
OPG is a crystal structure of almost perfect graphite, PG is a crystal having a crystal grain of about 200 angstroms and a little disordered, and GC is a crystal having a crystal grain of about 20 angstroms and a disorder of the crystal structure is further increased.) ,
Amorphous carbon (refers to amorphous carbon and a mixture thereof with the microcrystals of graphite);
The film thickness is preferably within a range of 50 nm or less.
It is more preferable to set the range to 0 nm or less.

6) It is preferable that the electron-emitting device obtained through such a process is subjected to a stabilization process. This process is a step of exhausting the organic substance in the vacuum container.
It is preferable to use a vacuum exhaust device that does not use oil so that the oil generated from the device does not affect the characteristics of the element. Specifically, a vacuum exhaust device such as a sorption pump or an ion pump can be used.

In the above-described activation process, when an oil diffusion pump or a rotary pump is used as an exhaust device and an organic gas derived from an oil component generated from the oil diffusion pump is used, the partial pressure of this component is kept as low as possible. There is a need. The partial pressure of the organic component in the vacuum vessel is preferably 1.3 × 10 ⁻⁶ Pa or less, particularly 1.3 × 10 ⁻⁸ Pa or less, at a partial pressure at which the above-mentioned carbon and carbon compounds are not newly deposited. More preferred.

When the inside of the vacuum vessel is further evacuated, it is preferable to heat the entire vacuum vessel so that the organic substance molecules adsorbed on the inner wall of the vacuum vessel and the electron-emitting device can be easily evacuated.
The heating condition at this time is 80 to 250 ° C., preferably 1 to
It is desirable to perform the treatment at 50 ° C. or higher for as long as possible, but the treatment is not particularly limited to this condition, and the treatment is performed under conditions appropriately selected from various conditions such as the size and shape of the vacuum vessel and the configuration of the electron-emitting device. . The pressure in the vacuum vessel needs to be as low as possible, and is preferably 1 × 10 ⁻⁵ Pa or less, more preferably 1.3 × 10 ⁻⁶ Pa or less.

The atmosphere during driving after the stabilization process is as follows:
It is preferable to maintain the atmosphere at the end of the stabilization process,
The present invention is not limited to this, and if the organic substance in the atmosphere is sufficiently removed, sufficiently stable characteristics can be maintained even if the degree of vacuum itself is slightly reduced. By employing such a vacuum atmosphere, the deposition of new carbon or a carbon compound can be suppressed, and H ₂ O, O _2, etc. adsorbed on a vacuum vessel or a substrate can be removed. As a result, the device current If , The emission current Ie is stabilized.

Next, basic characteristics of the electron-emitting device of the present invention obtained through the above-described processing steps will be described with reference to FIGS. FIG. 5 is a schematic diagram showing an example of a vacuum processing apparatus, and this vacuum processing apparatus also has a function as a measurement evaluation apparatus. In FIG. 5, the same parts as those shown in FIG. 1 are denoted by the same reference numerals. In FIG. 5, 55 is a vacuum vessel, and 56 is an exhaust pump. An electron-emitting device is provided in the vacuum vessel 55.

That is, reference numeral 1 denotes a base constituting an electron-emitting device, 2 and 3 denote device electrodes, 4 denotes a conductive thin film, and 5 denotes an electron-emitting portion. 51 is a device voltage V applied to the electron-emitting device.
f, an ammeter for measuring an element current If flowing through the conductive thin film 4 between the element electrodes 2 and 3, and 54 an emission current I emitted from an electron emission portion of the element.
This is an anode electrode for capturing e. Reference numeral 53 denotes a high-voltage power supply for applying a voltage to the anode electrode 54, and reference numeral 52 denotes an ammeter for measuring an emission current Ie emitted from the electron emission section 5 of the device. For example, the measurement can be performed with the voltage of the anode electrode in the range of 1 kV to 10 kV and the distance H between the anode electrode and the electron-emitting device in the range of 2 mm to 8 mm.

A vacuum gauge (not shown) is provided in the vacuum vessel 55.
Such devices as those required for measurement in a vacuum atmosphere are provided so that measurement and evaluation in a desired vacuum atmosphere can be performed. The exhaust pump 56 includes a normal high vacuum device system including a turbo pump and a rotary pump, and an ultrahigh vacuum device system including an ion pump and the like. The entire vacuum processing apparatus provided with the electron source substrate shown here can be heated up to 250 ° C. by a heater (not shown). Therefore, if this vacuum processing apparatus is used, the steps after the energization forming described above can also be performed.

FIG. 4 shows emission current Ie, device current If and device voltage V measured in the vacuum processing apparatus shown in FIG.
It is the figure which showed the relationship of f typically. In FIG.
Since the emission current Ie is significantly smaller than the element current If, it is shown in arbitrary units. The vertical and horizontal axes are linear scales. As is clear from FIG. 4, the surface conduction electron-emitting device to which the present invention can be applied has three characteristic properties with respect to the emission current Ie. That is, (i) the emission current Ie increases sharply when an element voltage higher than a certain voltage (referred to as a threshold voltage, Vth in FIG. 4) or more is applied, whereas when the element voltage is lower than the threshold voltage Vth, the emission current Ie is increased. Ie is hardly detected. That is, the emission current Ie
Is a non-linear element having a clear threshold voltage Vth.

(Ii) Since the emission current Ie depends monotonically on the device voltage Vf, the emission current Ie can be controlled by the device voltage Vf.

(Iii) The emission charge captured by the anode electrode 54 depends on the time during which the device voltage Vf is applied. That is, the amount of charge captured by the anode electrode 54 can be controlled by the time during which the device voltage Vf is applied.

As will be understood from the above description, the surface conduction electron-emitting device to which the present invention can be applied can easily control the electron emission characteristics according to the input signal. Utilizing this property enables application to various fields such as an electron source and an image forming apparatus configured by disposing a plurality of electron-emitting devices.

In FIG. 4, an example in which the element current If monotonically increases with respect to the element voltage Vf (hereinafter referred to as "MI characteristic") is shown by a solid line. The element current If may exhibit a voltage-controlled negative resistance characteristic (hereinafter, referred to as “VCNR characteristic”) with respect to the element voltage Vf. These characteristics can be controlled by controlling the aforementioned steps.

FIG. 6 shows the waveforms of If and Ie when a triangular wave having the maximum voltage Vm is applied to the surface conduction electron-emitting device. FIG. 6A shows the case of a surface conduction electron-emitting device in which a coating of a high-conductivity material is not formed.
h, the characteristic has a characteristic that Ie increases as If increases. FIG. 6B shows a case of a surface conduction electron-emitting device in which a film of a high conductivity material is formed.
a is equivalent to the connected one. As shown in FIG. 6B, the waveform of If becomes a waveform obtained by adding an ohmic current to the waveform of If of FIG. 6A.

In general, Ie / If is defined as the electron emission efficiency η, and the larger the efficiency η, the better. Therefore, an increase in If as shown in FIG. 6B degrades the characteristics of the surface conduction electron-emitting device. . For this reason, the resistance value of the film of the high conductivity material is controlled to be sufficiently high, and the leak current flowing through the film of the high conductivity material is sufficiently small compared to the device current observed during electron emission. Need to control small.

Next, an application example of the electron-emitting device according to the present invention will be described below. Here, a plurality of the above-described surface conduction electron-emitting devices are arranged on a substrate to form, for example, an electron source or an image forming apparatus. Various arrangements of the electron-emitting devices can be adopted.

As an example, the electron-emitting device is set in the X direction and the Y direction.
One of the electrodes of the plurality of electron-emitting devices arranged in a matrix in the direction, and one of the electrodes of the plurality of electron-emitting devices arranged in the same row is commonly connected to the wiring in the X direction, and the electrodes of the plurality of electron-emitting devices arranged in the same column Is commonly connected to the wiring in the Y direction.
Such is a so-called simple matrix arrangement, which will be described in detail below.

The surface conduction electron-emitting device according to the present invention has the following characteristics (i) to (iii) as described above. That is, the electrons emitted from the surface conduction electron-emitting device are
Above the threshold voltage, it can be controlled by the peak value and width of the pulse voltage applied between the opposing element electrodes. On the other hand, when the voltage is equal to or lower than the threshold voltage, it is hardly 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 devices, a surface-conduction electron-emitting device is selected according to an input signal to emit electrons. You can control the amount.

Hereinafter, based on this principle, an electron source substrate obtained by arranging a plurality of electron-emitting devices to which the present invention can be applied will be described. In FIG. 7, reference numeral 41 denotes an electron source substrate,
42 is an X direction wiring, and 43 is a Y direction wiring. Reference numeral 44 denotes a surface conduction electron-emitting device, and reference numeral 45 denotes a connection.

The m X-direction wirings 42 are Dx1, Dx
2,... Dxm, and can be formed of a conductive metal formed by a vacuum deposition method, a printing method, a sputtering method, or the like. The material, thickness and width of the wiring are appropriately designed. The Y-direction wiring 43 includes n wirings Dy1, Dy2,... Dyn, and is formed in the same manner as the X-direction wiring. These m
An interlayer insulating layer (not shown) is provided between the X-directional wirings 42 and the n Y-directional wirings 43 to electrically separate them (m and n are both positive). Integer).

This interlayer insulating layer is formed by a vacuum deposition method, a printing method,
It is composed of a material such as SiO ₂ formed by using a sputtering method or the like. For example, the entire surface area of the substrate 41 on which the X-directional wiring 42 is formed is formed in a desired shape in part, and in particular, the film is formed so as to withstand the potential difference at the intersection of the X-directional wiring 42 and the Y-directional wiring 43. The thickness, material, and manufacturing method are appropriately set. Note that the X-direction wiring 42 and the Y-direction wiring 43
Each is drawn out as an external terminal.

A pair of electrodes (not shown) forming the surface conduction electron-emitting device 44 are electrically connected by m X-directional wires 42, n Y-directional wires 43, and a connection 45 made of a conductive metal or the like. Connected. Wiring 42 and Wiring 43
, The material forming the connection 45, and the material forming the pair of element electrodes may have some or all of the same or different constituent elements. These materials are appropriately selected, for example, from the above-described materials for the device electrodes. In the case where the material forming the element electrode is the same as the wiring material, the wiring connected to the element electrode can be called an element electrode, in other words.

The coating (not shown) of the high conductivity material is formed on the interlayer insulating layer or the surface of the insulating substrate, and a part thereof is formed in contact with at least one of the wiring and the element electrode. A scanning signal applying unit (not shown) for applying a scanning signal for selecting a row of the surface conduction electron-emitting devices 44 arranged in the X direction is connected to the X-direction wiring 42. On the other hand, a modulation signal generating means (not shown) for modulating each column of the surface conduction electron-emitting devices 44 arranged in the Y direction according to an input signal is provided in the Y-direction wiring 43.
Is connected. The driving voltage applied to each electron-emitting device is supplied as a difference voltage between a scanning signal and a modulation signal applied to the device. In the above configuration, individual elements can be selected and driven independently using a simple matrix wiring.

FIGS. 8 and 9 show an image forming apparatus constructed using such an electron source having a simple matrix arrangement.
This will be described with reference to FIG. FIG. 8 is a schematic view showing an example of a display panel of the image forming apparatus, and FIG. 9 is a schematic view of a fluorescent film used in the image forming apparatus of FIG.

In FIG. 8, reference numeral 41 denotes an electron source substrate on which a plurality of electron-emitting devices are arranged, 31 denotes a rear plate on which the electron source substrate 41 is fixed, and 36 denotes a glass substrate 33 on which an inner surface of a fluorescent film 34 and a metal back 35 are provided. It is a formed face plate. Reference numeral 32 denotes a support frame, and the rear plate 31 and the face plate 36 are joined to the support frame 32 by using low melting point frit glass or the like as a sealing material.
Reference numeral 24 corresponds to the electron-emitting portion in FIG.
Reference numerals 22 and 23 are an X-direction wiring and a Y-direction wiring connected to a pair of device electrodes of the surface conduction electron-emitting device.

The envelope 37 includes the face plate 36, the support frame 32, and the rear plate 31, as described above. Since the rear plate 31 is provided mainly for the purpose of reinforcing the strength of the substrate 41, if the substrate 41 itself has sufficient strength, the separate rear plate 31 becomes unnecessary.
That is, the support frame 32 may be directly sealed to the substrate 41, and the face plate 36, the support frame 32, and the substrate 41 may constitute the entire envelope.

On the other hand, a support (not shown) called a spacer is provided between the face plate 36 and the rear plate 31.
, The envelope 37 having sufficient strength against the atmospheric pressure can be configured.

FIG. 9 is a schematic diagram showing the fluorescent film 34.
The fluorescent film 34 can be composed of only a phosphor in the case of a monochrome, but in the case of a color fluorescent film, a black stripe (FIG. 9A)
) Or a black matrix (see FIG. 9B) and a phosphor 39. The purpose of providing the black stripes and the black matrix is to make the color separation between the phosphors 39 of the necessary three primary color phosphors black in the case of color display, thereby making the color mixture and the like inconspicuous.
4 is to suppress a decrease in contrast due to external light reflection. As a material for the black stripe, a material having conductivity and having little light transmission and reflection can be used in addition to a material mainly containing graphite which is generally used.

As a method of applying the phosphor 34 on the glass substrate 33, a precipitation method, a printing method, or the like can be adopted regardless of monochrome or color. On the inner surface of the fluorescent film 34,
Usually, a metal back 35 is provided. The purpose of providing the metal back is to improve the brightness by reflecting the light toward the inner surface side of the light emitted from the phosphor to the face plate 36 side, thereby improving the brightness and acting as an electrode for applying an electron beam acceleration voltage. And protecting the phosphor from damage due to collision of negative ions generated in the envelope 37. In addition, the metal back, after the fluorescent film is made,
The fluorescent film can be formed by performing a smoothing process (usually called “filming”) on the inner surface of the fluorescent film, and then depositing Al using vacuum deposition or the like. Further, in the face plate 36, a transparent electrode (not shown) may be provided on the outer surface side of the fluorescent film 34 in order to further increase the conductivity of the fluorescent film 34. Furthermore, when performing the above-mentioned sealing, in the case of color display, it is necessary to make each color phosphor correspond to the electron-emitting device, and sufficient alignment is indispensable.

Next, an example of a method for manufacturing the image forming apparatus shown in FIG. 8 will be described with reference to FIG. FIG. 10 schematically shows an outline of an apparatus used for a process in this manufacturing method. Here, the image forming apparatus 131 includes an exhaust pipe 132
Is connected to the vacuum chamber 133,
It is connected to an exhaust device 135 via a gate valve 134. The vacuum chamber 133 has a pressure gauge 13 for measuring the internal pressure and the partial pressure of each component in the atmosphere.
6. A quadrupole mass analyzer 137 and the like are attached. Since it is practically difficult to directly measure the pressure inside the envelope of the image display device 131, the pressure inside the vacuum chamber 133 is measured and controlled as processing conditions.

The vacuum chamber 133 is further connected to a gas introduction line 138 for introducing a necessary gas to control the atmosphere. An introduction substance source 140 is connected to the other end of the gas introduction line 138. The substance to be introduced is stored in an ampoule or a cylinder. In the middle of the gas introduction line, there is provided an introduction control means 139 for controlling the rate at which the introduced substance is introduced. As a specific example of the introduction amount control means, a valve such as a slow leak valve capable of controlling a flow rate to be released, a mass flow controller, or the like can be used according to the type of the substance to be introduced.

With the apparatus shown in FIG. 10, the inside of the envelope 37 is evacuated and forming is performed. At this time, for example, as shown in FIG. Element 4 connected to one of direction wirings 42
4, a voltage pulse can be simultaneously applied by the power supply 142 to perform forming. Note that conditions such as the shape of the pulse and the determination of the end of the processing may be selected according to the method described above for the forming of the individual elements. In addition, by sequentially applying (scrolling) a pulse with a phase shifted to a plurality of X-direction wirings, it is possible to form elements connected to the plurality of X-direction wirings collectively. In the figure, reference numeral 143 denotes a current measuring resistor, and 144 denotes a current measuring oscilloscope.

After the forming is completed, an activation step is performed.
After exhausting sufficiently, the organic substance is introduced into the envelope 37 from the gas introduction line 138. Alternatively, as described in the method of activating individual exhaust, first, exhaust may be performed by an oil diffusion pump or a rotary pump, and thereby, an organic substance remaining in a vacuum atmosphere may be used. In addition, a substance other than the organic substance may be introduced as necessary.
By applying a voltage to each electron-emitting device in an atmosphere containing an organic substance formed in this way, carbon or a carbon compound, or a mixture of both, is deposited on the electron-emitting portion, and the electron emission amount is reduced. The movement to the stick is similar to that of the individual element. At this time, the voltage may be applied by applying the same voltage pulse to the elements 44 connected to one direction wiring by the same connection as in the above-described forming.

After the end of the activation process, it is preferable to perform the stabilization process in the same manner as in the case of the individual elements.
While the envelope 37 is heated and maintained at 80 to 250 ° C., the exhaust is exhausted through an exhaust pipe 132 by an exhaust device 135 that does not use oil, such as an ion pump and a sorption pump, to obtain an atmosphere containing a sufficiently small amount of organic substances. . Thereafter, the exhaust pipe is heated with a burner, melted, and sealed.

Note that a getter process can be performed to maintain the pressure after the envelope 37 is sealed. This is to heat a getter disposed at a predetermined position (not shown) in the envelope by heating using resistance heating or high-frequency heating immediately before or after sealing the envelope. 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 by the adsorption action of the deposited film.

Next, an example of the configuration of a drive circuit for performing television display based on NTSC television signals on a display panel configured using electron sources in a simple matrix arrangement will be described with reference to FIG. I do. 12, reference numeral 101 denotes an image display panel, 102 denotes a scanning circuit,
103 is a control circuit, and 104 is a shift register. Reference numeral 105 denotes a line memory, 106 denotes a synchronization signal separation circuit, 107 denotes a modulation signal generator, and Vx and Va denote DC voltage sources.

The display panel 101 has terminals Dox1 to Dox
xm, terminals Doy1 to Doyn, and a high voltage terminal Hv are connected to an external electric circuit. These terminals D
In ox1 to Doxm, electron sources provided in the display panel, that is, a group of surface conduction electron-emitting devices arranged in a matrix of M rows and N columns are sequentially driven one row (N element) at a time. Scan signal is applied.

Terminals Doy1 to Doyn are connected to one row of surface conduction electron-emitting devices selected by the scanning signal.
A modulation signal for controlling each output electron beam is applied. The high-voltage terminal Hv is supplied with a DC voltage of, for example, 10 kV from a DC voltage source Va, which is sufficient to excite the phosphor into an electron beam emitted from the surface conduction electron-emitting device. It is an accelerating voltage for applying energy.

Next, the scanning circuit 102 will be described. The circuit includes m switching elements (schematically indicated by S1 to Sm in the figure). Each switching element is connected to the output voltage of the DC voltage source Vx or 0
One of V (ground level) is selected, and is electrically connected to the terminals Dox1 to Doxm of the display panel 101. Each of the switching elements S1 to Sm operates based on the control signal Tscan output from the control circuit 103, and can be configured by combining switching elements such as FETs, for example.

The DC voltage source Vx is, in this case,
Based on the characteristics (electron emission threshold voltage) of the surface conduction electron-emitting device, a constant voltage is output so that the driving voltage applied to the unscanned device is equal to or lower than the electron emission threshold voltage. Is set.

The control circuit 103 has a function of matching the operation of each unit so that an appropriate display is performed based on an image signal input from the outside. The control circuit 103 controls the synchronization signal Tsync sent from the synchronization signal separation circuit 106.
, Tscan, Tsft, and Tmry control signals are generated for each unit.

The synchronizing signal separating circuit 106 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 (filter) circuit or the like. Can be configured. The synchronizing signal separated by the synchronizing signal separating circuit 106 includes a vertical synchronizing signal and a horizontal synchronizing signal. Here, for the sake of explanation, it is illustrated as a Tsync signal. The luminance signal component of the image separated from the television signal is referred to as a DATA signal for convenience. This DATA signal is input to the shift register 104.

The shift register 104 is for serially / parallel converting a DATA signal input serially in time series for each line of an image.
It operates based on the control signal Tsft sent from the control register 03 (that is, it can be said that the control signal Tsft is a shift clock of the shift register 104). The data for one line of the image that has been subjected to the serial / parallel conversion (corresponding to drive data for N electron-emitting devices) is output from the shift register 104 as N parallel signals Id1 to Idn.

The line memory 105 is a storage device for storing data for one line of an image for a necessary time only, and stores the contents of Id1 to Idn as appropriate according to a control signal Tmry sent from the control circuit 103. . The stored contents are output as I'd1 to I'dn and input to the modulation signal generator 107.

The modulation signal generator 107 outputs the image data I'd
1 to I′dn are signal sources for appropriately driving and modulating each of the surface conduction electron-emitting devices in accordance with each of the surface conduction electron-emitting devices. Applied to the electron-emitting device.

As described above, the electron-emitting device to which the present invention is applied has the following basic characteristics with respect to the emission current Ie. That is, a clear threshold voltage V is required for electron emission.
and electron emission occurs only when a voltage equal to or higher than Vth is applied. For a voltage equal to or higher than the electron emission threshold, the emission current also changes according to the change in the voltage applied to the device. From this, when a pulse-like voltage is applied to the element, for example, when a voltage lower than the electron emission threshold is applied, electron emission does not occur, but when a voltage higher than the electron emission threshold is applied, the electron beam is not emitted. Is output. At that time, the intensity of the output electron beam can be controlled by changing the peak value Vm of the pulse. Further, by changing the pulse width Pw, it is possible to control the total amount of charges of the output electron beam.

Therefore, as a method of modulating the electron-emitting device according to the input signal, a voltage modulation method, a pulse width modulation method, or the like can be employed. When implementing the voltage modulation method, a circuit of a voltage modulation method that generates a voltage pulse of a fixed length and appropriately modulates the peak value of the pulse according to input data is used as the modulation signal generator 107. Can be used.

In implementing the pulse width modulation method, the modulation signal generator 107 generates a voltage pulse having a constant peak value and modulates the width of the voltage pulse appropriately according to input data. A pulse width modulation type circuit can be used.

The shift register 104 and the line memory 10
5 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, the output signal DATA of the synchronization signal separation circuit 106 needs to be converted into a digital signal.
A converter may be provided. In this connection, the circuit used for the modulation signal generator 107 differs slightly depending on whether the output signal of the line memory 105 is a digital signal or an analog signal. That is, in the case of the voltage modulation method using a digital signal, the modulation signal generator 107 includes, for example,
A D / A conversion circuit is used, and an amplification circuit and the like are added as necessary. In the case of the pulse width modulation method, the modulation signal generator 1
In 07, for example, a high-speed oscillator, a counter (counter) for counting the number of waves output from the oscillator, and a circuit combining a comparator (comparator) for comparing the output value of the counter with the output value of the memory are provided. Used. If necessary, an amplifier for amplifying the voltage of the pulse-width-modulated signal output from the comparator to the drive voltage of the surface-conduction electron-emitting device can be added.

In the case of the voltage modulation method using an analog signal, for example, an amplification circuit using an operational amplifier or the like can be used as the modulation signal generator 107, and a level shift circuit or the like can be added as necessary. . In the case of the pulse width modulation method, for example, a voltage-controlled oscillation circuit (VO
C) can be adopted, and if necessary, an amplifier for amplifying the voltage up to the driving voltage of the surface conduction electron-emitting device can be added.

In the image display apparatus to which the present invention can be applied in such a configuration, electron emission is performed by applying a voltage to each electron-emitting device via the external terminals Dox1 to Doxm and Doy1 to Doyn. Occurs. Further, a high voltage is applied to the metal back 85 or a transparent electrode (not shown) via the high voltage terminal Hv to accelerate the electron beam. The accelerated electrons collide with the fluorescent film 84,
As a result, light emission occurs and an image is formed.

The configuration of the image forming apparatus described here is an example of the image forming apparatus according to the present invention, and various modifications are possible based on the technical idea of the present invention. Although the NTSC system has been described as the input signal, the input signal is not limited to this, and PAL, SEC
In addition to the AM system, a TV signal composed of a larger number of scanning lines (for example, a high-quality T
V) system can also be adopted.

FIG. 13A shows a schematic configuration and an electron beam corresponding to one pixel of an image forming apparatus as shown in FIG. 8 using an electron source in which a plurality of surface conduction electron-emitting devices are arranged in a matrix. Shows the flying state of. Here, reference numeral 75 denotes a high-potential-side device electrode, 76 denotes a low-potential-side device electrode, and 78 denotes a bright spot. FIG. 13B is an enlarged schematic view of the fluorescent spot 78 of the phosphor observed by the present inventors in the device as shown in FIG.

As shown in FIG. 13A, the entire luminescent spot of the phosphor is in the direction in which the voltage is applied to the element electrode (X direction in the figure) and in the direction perpendicular to it (Y direction). It was confirmed that it had spread. The reason why such a bright spot is formed, that is, the reason why the electron beam reaches the image forming member with a certain spread, is not clearly understood because the electron emission mechanism of the surface conduction electron-emitting device has not been completely elucidated. Although it cannot be explained, the present inventors believe that electrons having an initial velocity are emitted so as to be scattered in all directions from many experiments. Also, of the electrons emitted in all directions, the electrons emitted in the direction of the high-potential element electrode (in the figure, the X plus direction) reach the tip of the luminescent spot, and are directed in the direction of the low-potential element electrode (in the figure) , X
It is estimated that the amount of electrons emitted in the negative direction) is very small.

Further, according to the experiment of the present inventors, FIG.
In (a) and (b), it was found that the luminescent spot 78 was displaced from vertically above the electron-emitting portion 74 in the X-plus direction, that is, toward the high-potential-side device electrode 75. This is because, as shown in FIG. 14, the potential distribution in the space above the surface conduction electron-emitting device is such that the equipotential surface is not parallel to the surface of the image forming member 86 in the vicinity of the electron-emitting portion 74. The emitted electrons are accelerated by the acceleration voltage Va, and not only fly in the Z direction in the figure, but also
The present inventors believe that acceleration is also performed in five directions.
That is, it is considered that it is inevitable that electrons are subjected to a deflecting action immediately after they are emitted due to the applied voltage Vf necessary for emitting electrons.

The shape and size of the luminescent spot 78 and the electron emitting portion 74
From the examination of the value of the position shift in the X direction from above vertically, the shift amount to the tip of the bright spot (ΔX1 in (b) of FIG. 13),
The amount of shift to the tail of the bright spot (ΔX2 in FIG. 13B),
Also, it can be understood that the size (ΔY) of the electron beam spot in the Y direction on the image forming member surface can be represented by using Va, Vf, and H as parameters (Japanese Patent Laid-Open No. 6-342636).
Reference).

Further, as a result of measuring the bright spot distribution within the bright spot, it was found that the amount of electrons reaching the face plate had the distribution shown in FIG. That is, in FIG.
It was required that 50% or more of the emitted electrons were concentrated on the luminescent spot 79. Vf is 10 to 20 V, Va is 1 kV to 10 k
V, the distance H between the face plate and the electron source substrate is 2 mm
In the range of ８8 mm, the coordinate ΔX of the luminance center 79 of this luminescent spot could be expressed by the following equation. ΔX = K1 × H × √ (Vf / Va) + K2 where K1 and K2 are constants, and K1 is approximately 2, K2
Is almost zero.

In the case of simple matrix driving as described above, it is desirable that the current flowing during half-selection (non-driving element) is sufficiently smaller than the current flowing during selection (driving element). In general, the voltage applied to the surface conduction electron-emitting device during half-selection is １ ／ of the voltage (drive voltage Vop) applied during selection. If the current at that time is set to be equal to or less than 1 / (the number of elements in one line n) of the current at the time of selection, the power consumed by the non-driven elements can be suppressed to approximately the same level as the power consumed by the driven elements. To achieve this, a highly conductive film is selectively formed on the insulating surface of the electron source substrate in the direction of the normal to the luminance center of the bright spot. On the insulating surface in the normal direction of the luminescent spot, the charge can be prevented by discharging the electric charge to the wiring or the electrode in contact with the highly conductive film through the highly conductive film.

On the other hand, on the insulating surface where no bright spot is formed in the normal direction, the current flowing at the time of half-selection can be minimized, and the power consumption can be reduced. Thus, it is possible to obtain an image forming apparatus in which power consumption is reduced and the image is not disturbed or the elements are not deteriorated due to discharge.

[0104]

The present invention will be specifically described below with reference to examples. This embodiment is an example of an image forming apparatus in which many surface conduction electron-emitting devices are arranged in a simple matrix. First,
FIG. 16 shows a partial plan view of the electron source (the enlarged view of FIG. 17). Here, reference numeral 41 denotes a substrate, 42 denotes an X-direction wiring (also referred to as a lower wiring) corresponding to Doxm in FIG. 8, 43 denotes a Y-direction wiring (also referred to as an upper wiring) corresponding to Doyn in FIG.
4 is a thin film including an electron-emitting portion, 45 and 46 are device electrodes,
7 is an interlayer insulating layer.

Next, the manufacturing method will be specifically described in the order of steps with reference to FIGS. 16, 17 and 18.

[Step-a] The glass substrate 41 is washed. The substrate used was blue plate glass.

[Step-b] The device electrodes 45 and 46 are formed. A thick film printing method was used as a film forming method. The thick film paste material used here is MOD paste (D
U-2110, manufactured by Noritake Co., Ltd.), and the metal component is gold. The printing method is a screen printing method.
After printing, drying is performed at 110 ° C. for 20 minutes, and then main firing is performed. The firing temperature is 580 ° C. and the peak retention time is about 8 minutes. The film thickness after printing and baking was 0.3 μm.
The distance between the device electrodes was 50 μm.

[Step-c] Next, the Y-direction wiring 43 is formed. Thick film screen printing was used. The paste material is Noritake Co., Ltd. product (NP-4028A), and the metal component is silver. The firing is the same as in [Step-b]. The film thickness after printing and baking was 10 μm. In addition,
The Y-direction wiring is connected to one side of the element electrode 45.

[Step-d] Next, an interlayer insulating layer 47 is formed. Thick film screen printing was used. The paste material used was a mixture of PbO as a main component and a glass binder. The firing is the same as in [Step-b]. The film thickness after printing and baking was 30 μm. In addition,
The configuration is such that the X-direction wiring and the element electrode 46 can be connected.

[Step-e] Next, the X-direction wiring 42 is
It is formed in the same procedure as the Y-direction wiring 43. The film thickness after printing and baking was 10 μm. Further, a part of the X-direction wiring 42 is connected to the element electrode 46.

[Step-f] Next, a conductive thin film 44 is formed. An organic palladium-containing solution was applied so as to have a width of 80 μm by using a bubble jet type inkjet ejecting apparatus. A heat treatment was performed at 300 ° C. for 10 minutes to obtain a fine particle film composed of fine palladium oxide particles.

[Step-g] Next, a coating 48 of a highly conductive material was formed on the substrate surface. The carbon-containing dispersion was applied using a bubble jet type ink jet injection device. Thereafter, the film was dried at 200 ° C. to form a film of a high conductivity material.

Through the above steps, X on the insulating substrate 41
The directional wiring 42, the interlayer insulating layer 47, the Y-directional wiring 43, the device electrodes 45 and 46, and the thin film 44 for forming the electron emission portion were formed. The shape of the device electrodes 45 and 46 and the dimensions of each member are Lx =
300 μm, Ly = 700 μm, L2 = 500 μm, L
3 = 100 μm, L4 = L5x = L6 = Li = 50 μ
m, L5y = 100 μm, and L7 = 600 μm.

Next, an electron source and a display were constructed using the electron source substrate prepared as described above. This will be described with reference to FIGS. That is, after fixing the substrate 21 on which the element is formed as described above on the rear plate 31, the face plate 36 (the fluorescent film 34 and the metal back on the inner surface of the glass substrate 33) is placed above the distance H (4 mm) of the substrate 21. 35 is formed via the support frame 32, frit glass is applied to the joint between the face plate 36, the support frame 32, and the rear plate 31, and baked at 400 ° C. for 10 minutes or more in the atmosphere. It was sealed. The fixing of the substrate 21 to the rear plate 31 was also performed with frit glass. In this embodiment, 24 in FIG.
Are the electron-emitting devices before the formation of the electron-emitting portion;
Reference numeral 3 denotes element wirings in the X and Y directions, respectively.

The fluorescent material of the fluorescent film 24 adopts a stripe shape (see FIG. 9). First, a black stripe 38 is formed.
4 was created. As a material for the black stripe, a material mainly containing graphite, which is commonly used, was used.
A slurry method was used as a method of applying the phosphor on the glass substrate 33. A metal back 35 is usually provided on the inner surface side of the fluorescent film 34.
After the formation of the fluorescent film, a smoothing treatment (usually called filming) of the inner surface of the fluorescent film is performed.
1 was prepared by vacuum evaporation.

In the face plate 36, a transparent electrode (not shown) may be provided on the outer surface side of the fluorescent film 34 in order to further enhance the conductivity of the fluorescent film 34, but in this embodiment, a metal back is provided. Alone, sufficient conductivity was obtained, and was omitted. In addition, when performing the above-described sealing, sufficient alignment was performed so that the phosphors of each color and the electron-emitting devices had to correspond to each other.

The atmosphere in the glass container completed as described above is exhausted by a vacuum pump through an exhaust pipe (not shown), and after reaching a sufficient degree of vacuum, the terminal Dox outside the container.
A voltage was applied between the electrodes 45 and 46 of the electron-emitting device 24 through 1 to Doxm and Doy1 to Doyn to form the electron-emitting portion forming thin film 24. FIG. 3 shows a voltage waveform of the forming process.

In this embodiment, T1 is 1 ms, and T2 is 10
m seconds, about 1 × 10^-FivePerformed in a torr vacuum atmosphere
Was. The electron emission part created in this way is
Fine particles mainly containing element are dispersed and arranged,
The average particle size of the fine particles was 3 nm. Next,
The same rectangular wave as that of Ming, wave height 7V, degree of vacuum 2 × 10 ^-Five
At a degree of vacuum of torr, the device current If and the emission current I
While measuring e, a high resistance activation treatment was performed.

After performing such forming and activation processes to form an electron-emitting portion and to form an electron-emitting device,
Evacuation was performed to a degree of vacuum of about 10 ⁻⁶ torr, and an exhaust pipe (not shown) was heated and welded with a gas burner to seal the envelope. Finally, gettering was performed by a high-frequency heating method in order to maintain the degree of vacuum after sealing.

In the image display device of the present invention completed as described above, each of the electron-emitting devices has an external terminal Dox1.
To Doxm and Doy1 to Doyn, respectively, to apply a voltage Vf, thereby outputting a scanning signal and a modulation signal by a signal generation means (not shown) to emit electrons, and a metal back 35 through a high voltage terminal Hv. High voltage V
a, the electron beam is accelerated to collide with the fluorescent film 34 to excite and emit light.
A bright spot was formed on the top and the image was displayed.

The device current If and the emission current Ie are both shown by solid lines in FIG. Further, at this time, the emission current was able to correspond to the luminance of 100 fL to 150 fL required for the television.

In the present embodiment, the center coordinate ΔX of the above-mentioned bright spot can be expressed by the following equation. ΔX = K1 × H × √ (Vf / Va) + K2 where K1 = 2.0 and K2 = −6.25e−5.

Comparative Example 1 This comparative example is an example in which a film made of a highly conductive material is not formed on the electron source substrate. Here, in the above configuration, the image forming apparatus was configured with H = 4 mm. When a voltage Vf = 10 V is applied between the element electrodes 45 and 46 by the element driving power supply 81, electrons are emitted from the electron emission section 4
4 released. When an acceleration voltage Va is applied to the phosphor 34 from the electron beam acceleration power source 82 via the metal back 35, the electrons are accelerated and collide with the phosphor 34,
The light is emitted to form a bright spot on the face plate 33.

In the electron source substrate of this comparative example, the direction from the electron emission portion to the high potential side electrode (X plus direction) is 175 to 175.
The insulating surface is exposed at a position of 225 μm. Thus, H
= 4 mm and Vf = 10 V, when Va is 8 kV or more, the luminance center of the luminescent spot becomes 220 μm or less according to the above equation, and is located in the normal direction of the insulating surface. In fact, at an acceleration voltage of 8 kV or more, the shape of the luminescent spot changed, the formed image became unstable, and deterioration of the element due to discharge was observed.

In this comparative example, the number of elements in one line was 480, and the current flowing through the driving element was about 1 mA per element. At this time, the voltage applied to the surface conduction electron-emitting device during half-selection is 5V. If the current at this time is set to 2 μA or less, the power consumed by the non-driving element can be suppressed to substantially the same as the power consumed by the driving element as described above.

Comparative Example 2 This comparative example is an example in which a coating of a high conductivity material is uniformly formed on the entire surface of the electron source substrate. Here, [Step-g] will be described in detail. Note that a carbon thin film was used as the coating of the high conductivity material. Carbon pigment (cumulative average particle size 1)
0 nm) (a pigment concentration of 0.1%). This carbon dispersion was applied once to the entire surface of the substrate except for the thin film for element formation by using a bubble jet type inkjet ejecting apparatus. When one droplet (one dot) is applied, the droplet becomes circular. However, one dot is applied at regular intervals so as to cover the entire insulating surface. Thereafter, the film was dried at 200 degrees for 10 minutes to form a film of a high conductivity material.

Next, the measurement of the sheet resistance of the coating of the high conductivity material will be described. Under the same conditions as in this comparative example, a carbon dispersion liquid was applied on a glass substrate, and a heat treatment was performed at 200 degrees for 10 minutes. The sheet resistance of the applied sample was measured by a four-terminal method. At this time, the sheet resistance is 2 × 10e8Ω.
/ □. The relationship between the solution concentration and the resistance value is as follows:
The above relationship is not universal, although it can be changed by the ink jet ejection condition and the substrate condition.

Then, an image was formed in the same manner as in Comparative Example 1. In this comparative example, the current that flowed during the half-selection was 0.5 μA per element, and the power consumption during driving described above did not matter. However, at an accelerating voltage of up to 10 kV, although the deterioration of the element due to the discharge was suppressed, the shape of the luminescent spot changed and the formed image was unstable.

Comparative Example 3 This comparative example is also an example in which a coating of a highly conductive material is uniformly formed on the entire surface of the electron source substrate. The carbon dispersion used in [Step-g] is the same as in Comparative Example 2. This was applied twice to the entire surface of the substrate except for the thin film for element formation, using a bubble jet type inkjet ejecting apparatus. At this time, after the first application, a second application was performed after a certain time (after about 1 second) until the applied droplets lost fluidity. Thereafter, the coating was dried at 200 ° C. for 10 minutes to form a coating of a high conductivity material.

The measurement of the sheet resistance of the coating of the highly conductive material at this time is as follows. Under the same conditions as in this comparative example, a carbon dispersion was applied on a glass substrate, and a heat treatment was performed at 200 ° C. for 10 minutes. , The sheet resistance of the applied sample,
The sheet resistance measured by the four-terminal method was 1 × 10
e7Ω / □. Note that the relationship between the solution concentration and the resistance value can be changed depending on the ink jet ejection conditions and the substrate conditions, so the above relationship is not universal.

In this comparative example, an image was formed in the same manner as in comparative example 1. In this comparative example, the current that flowed during the half-selection was 5.5 μA per element, and the power consumption during driving was significantly increased. However, a stable bright spot was formed at an acceleration voltage of up to 10 kV, and a good image was obtained.

Example 1 Next, the covering state of the highly conductive material on the insulating substrate in the direction (X wiring direction) connecting the positions where the bright spots are formed from the electron-emitting portions and on the other insulating substrates will be described. The changed case will be described (see FIG. 19). The carbon dispersion used in [Step-g] is the same as in Comparative Example 2. This was applied to the insulating surface of (ii) in FIG.
One time was applied to the insulating surface of (i) and (iii). Thereafter, the coating was dried at 200 ° C. for 10 minutes to form a coating of a high conductivity material.

Here, an image was formed in the same manner as in Comparative Example 1. However, in this embodiment, the current flowing during half-selection was 1.5 μA per element, and the power consumption during driving described above was It did not matter. Further, a stable bright spot was formed at an acceleration voltage of up to 10 kV, and a good image was obtained.

(Embodiment 2) The present embodiment shown below is an example in which a high-conductivity conductive material is selectively coated on an insulating surface in a normal direction of a luminance center of a luminescent spot. In the electron source substrate of the present embodiment,
The insulating surface is exposed at a position of 175 to 225 μm in the direction from the electron emission portion to the high potential side electrode (X plus direction). When Va is 10 kV when H = 4 mm and Vf = 10 V, the luminance center of the luminescent spot is shifted by 190 μm in the X plus direction from the electron emission portion and is located in the normal direction of the insulating surface according to (Expression). Drops were applied to cover the insulating surface at a position of 190 μm in the X plus direction with a high conductivity material.

The carbon dispersion used in [Step-g] is the same as in Comparative Example 2. Using a bubble jet type ink jet device, this is 20 μm in the Y direction.
The application was performed 5 times with a shift of m intervals. Then 2
The coating was dried at 00 ° C. for 10 minutes to form a coating 48 of a highly conductive material. At this time, the coating of the high-conductivity material was applied to the area of 30 μm in the X direction and 160 μm in the Y direction only in contact with the wiring in the Y direction (see FIG. 20).

The measurement of the sheet resistance of the coating of the highly conductive material is as follows. That is, under the same conditions as in the above-described comparative example, a carbon dispersion liquid was applied on a glass substrate,
For 10 minutes. The sheet resistance of the applied sample was measured by a four-terminal method. At this time, the sheet resistance was 2 × 10e6Ω / □. Note that the relationship between the solution concentration and the resistance value can be changed depending on the ink jet ejection conditions and the substrate conditions, so the above relationship is not universal.

Here, an image was formed in the same manner as in Comparative Example 1, except that the acceleration voltage was fixed at 10 kV. In this embodiment, the current that flows during the half-selection is 1 per element.
μA or less, and the power consumption during driving described above did not matter. Thus, also in this example, a stable luminescent spot was formed, and a good image was obtained.

[0138]

As described above, the present invention relates to an image forming apparatus using a surface conduction electron-emitting device.
By appropriately determining the covering state of the high-conductivity material according to the position of the insulating substrate and the bright spot, power consumption can be suppressed and the trajectory of the electron beam can be made extremely stable.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of a surface conduction electron-emitting device of the present invention.

FIG. 2 is a schematic view showing one example of a method for manufacturing a surface conduction electron-emitting device according to the present invention.

FIG. 3 is a schematic diagram showing an example of a voltage waveform in an energization forming process that can be employed in manufacturing the surface conduction electron-emitting device.

FIG. 4 is a graph showing an example of the relationship between the emission current Ie, the device current If, and the device voltage Vf for the surface conduction electron-emitting device.

FIG. 5 is a schematic diagram illustrating an example of a vacuum processing apparatus having a measurement evaluation function.

FIG. 6 is a diagram for explaining characteristics of the surface conduction electron-emitting device of the present invention.

FIG. 7 is a schematic diagram showing an example of an electron source having a simple matrix arrangement to which the present invention is applied.

FIG. 8 is a schematic diagram illustrating an example of a display panel of an image forming apparatus to which the present invention has been applied.

FIG. 9 is a schematic view showing an example of the fluorescent film.

FIG. 10 is a schematic diagram of a vacuum evacuation apparatus for performing a forming and activating process of the image display device of the present invention.

FIG. 11 is a schematic diagram illustrating a connection method for forming and activation processing steps of the image forming apparatus of the present invention.

FIG. 12 is a block diagram showing an example of a drive circuit for performing display according to an NTSC television signal as the image forming apparatus of the present invention.

FIG. 13 is a perspective view showing a configuration of one pixel of the image forming apparatus of the present invention and a diagram showing a bright spot shape observed by a surface conduction electron-emitting device.

FIG. 14 is an equipotential diagram for explaining the trajectory of an electron beam of an image display device using a surface conduction electron-emitting device.

FIG. 15 is a diagram showing a distribution of the charge amount of a bright spot observed in the surface conduction electron-emitting device.

FIG. 16 is a schematic diagram showing an example of an electron source having a simple matrix arrangement to which the present invention is applied.

FIG. 17 is also an enlarged schematic diagram.

FIG. 18 is a diagram illustrating a manufacturing process of the electron source substrate according to the embodiment of the present invention.

FIG. 19 is a diagram for explaining an embodiment according to the present invention.

FIG. 20 is a diagram for explaining the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Substrate 2, 3 Element electrode 4 Conductive thin film 5 Electron emission part 21 Electron source substrate 22 X direction wiring 23 Y direction wiring 24 Surface conduction type electron emitting element 31 Rear plate 32 Support frame 33 Glass substrate 34 Fluorescent film 35 Metal back 36 Face plate 37 envelope 38 black conductive material 39 phosphor 41 electron source substrate 42 X-direction wiring 43 Y-direction wiring 44 surface conduction electron-emitting device 45 device electrode 46 device electrode 47 interlayer insulating layer 48 coating film of high conductive material 50, 52 Ammeter 51 Power supply for applying element voltage Vf to electron-emitting device 53 High-voltage power supply for applying voltage to anode 54 54 Anode electrode for capturing emission current Ie 55 Ammeter 56 Vacuum device 57 Exhaust pump 71 electron source substrate 74 surface conduction electron-emitting device 75 high-potential side device electrode 76 Potential side device electrode 78 Bright spot 79 Main component of bright spot 81 Power supply for applying device voltage Vf to electron-emitting device 82 Voltage power supply for applying voltage to anode electrode 86 Face plate 93 Glass substrate 101 Display panel 102 Scan Circuit 103 Control circuit 104 Shift register 105 Line memory 106 Synchronous signal separation circuit 107 Modulation signal generator 131 Image display device 132 Exhaust pipe 133 Vacuum chamber 134 Gate valve 135 Exhaust device 136 Pressure gauge 137 Quadrupole mass analyzer 138 Gas introduction line 139 Introduced amount control means 140 Introduced substance source 141 Common electrode 142 Power supply 143 Current measuring resistor 144 Oscilloscope Vx and Va DC voltage source

Claims (5)

[Claims] 1. A plurality of surface conduction electron-emitting devices each having an X-direction wiring and a Y-direction wiring laminated on an insulating substrate via an interlayer insulating layer, and a thin film including an electron-emitting portion between a pair of device electrodes. An electron source substrate having element electrodes of the plurality of surface conduction electron-emitting devices connected to the X-direction wiring and the Y-direction wiring and arranged in a matrix, An image forming apparatus comprising: a face plate having a phosphor target facing each other so as to receive irradiation of an electron beam from each of the electron-emitting devices; In the linear direction, the surface of the insulating substrate on the electron source substrate is selectively coated with a material having higher conductivity than the substrate material, and the high conductivity material is used for the device electrode and the wiring. An image forming apparatus, which is coated in contact with at least one of: 2. The high conductivity material has a sheet resistance of 10e8.
The image forming apparatus according to claim 1, wherein the value is Ω / □ or less. 3. The image forming apparatus according to claim 1, wherein the dispersion containing the conductive material is applied as one or more droplets to form a highly conductive material. Production method. 4. The method for manufacturing an image forming apparatus according to claim 3, wherein the application of the droplet is performed by an ink jet method. 5. The method for manufacturing an image forming apparatus according to claim 4, wherein the ink-jet method is a method in which bubbles are formed in the dispersion by thermal energy and the dispersion is discharged as droplets.