JP3548431B2 - Electron source and image forming apparatus using the electron source - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electron source using an electron-emitting device and an image forming apparatus using the electron source.
[0002]
[Prior art]
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. The cold cathode electron emitting device includes a field emission type (hereinafter, referred to as “FE type”), a metal / insulating layer / metal type (hereinafter, referred to as “MIM type”), a surface conduction type electron emitting device, and the like. As an example of the FE type, W. P. Dyke & W. W. Dolan, "Field Emission", Advance in Electron Physics, 8, 89 (1956) or C.I. A. Spindt, "Physical Properties of Thin-Film Field Emission Cathodes with Molybdenium Cones", J. Am. Appl. Phys. , 47, 5248 (1976).
[0003]
Examples of the MIM type include C.I. A. Mead, "Operation of Tunnel-Emission Devices", J. Mol. Apply. Phys. , 32, 646 (1961).
[0004]
As an example of the surface conduction electron-emitting device type, see, I. Elinson, Recio Eng. Electron Phys. , 10, 1290 (1965).
[0005]
The surface conduction electron-emitting device utilizes a phenomenon in which an electron is emitted when a current flows through a small-area thin film formed on a substrate in parallel with the film surface. As the surface conduction electron-emitting device, SnO by Elinson et al. ₂ One using a thin film, one using an Au thin film [G. Dittmer: “Thin Solid Films”, 9, 317 (1972)], In ₂ O ₃ / SnO ₂ By a thin film [M. Hartwell and C.I. G. FIG. Fonstad: "IEEE Trans. ED Conf.", 519 (1975)], and a method using a carbon thin film [Hisashi Araki et al .: Vacuum, Vol. 26, No. 1, p. 22 (1983)] and the like are reported.
[0006]
As a typical example of these surface conduction electron-emitting devices, the aforementioned M.I. FIG. 16 schematically shows an element configuration of the Hartwell. In the figure, reference numeral 6 denotes an insulating 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 emitting portion 5 is formed by an energization process called energization forming described later. The element electrode interval L in the figure is set to 0.5 to 1 mm, and W 'is set to 0.1 mm.
[0007]
Conventionally, in these surface conduction electron-emitting devices, it has been general that the electron-emitting portion 5 is formed beforehand by the energization process called energization forming of the conductive thin film 4 before electron emission. That is, the energization forming is to apply a direct current voltage or a very slowly increasing voltage, for example, about 1 V / min, to both ends of the conductive thin film 4 and to energize the conductive thin film 4 to locally destroy, deform or alter the conductive thin film, and The purpose is to form the electron emitting portion 5 in a high resistance state. In the electron emitting portion 5, a crack is generated in a part of the conductive thin film 4, and electrons are emitted from the vicinity of the crack. The surface conduction type electron-emitting device which has been subjected to the energization forming treatment causes the electron-emitting portion 5 to emit electrons by applying a voltage to the conductive thin film 4 and causing a current to flow through the device.
[0008]
In the case of the conventional surface conduction electron-emitting device, there is a problem that the trajectory of the emitted electron beam becomes unstable because the potential of the insulating substrate 6 on which the emission device is formed is unstable. In order to solve this problem, a method has been proposed in which a potential regulating means is provided near the electron-emitting device to regulate the surface potential of the insulating substrate 6 (for example, Japanese Patent Application Laid-Open No. 1-283735).
[0009]
The surface conduction electron-emitting device described above has an advantage that a large number of devices can be arranged and formed over a large area because the structure is simple and the production is easy. Therefore, various applications that can take advantage of this feature are being studied. For example, there are a charged beam source, a display device, and the like. As an example in which a large number of surface conduction electron-emitting devices are arranged and formed, as will be described later, surface conduction electron-emitting devices are arranged in parallel, and both ends of each device are connected by wiring (also referred to as common wiring). An electron source having a large number of rows arranged (for example, JP-A-64-031332, JP-A-1-283737, JP-A-2-257552, etc.) can be mentioned. In particular, in image forming apparatuses such as display apparatuses, flat panel display apparatuses using liquid crystal have recently spread in place of CRTs. However, since they are not self-luminous, they must have a backlight. There is a problem, and development of a self-luminous display device has been desired. As the self-luminous display device, there is an image forming apparatus which is a display device in which an 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 are combined. Can be (For example, US Pat. No. 5,066,883)
[0010]
[Problems to be solved by the invention]
In the electron source device in which a large number of elements are arranged and formed over a large area, there is a problem that the orbit of the emitted electrons is not only stable but also can be driven stably for a long time. Discharge is one of the causes of unstable operation or deterioration of uniformity as an electron source due to long-time driving. This discharge phenomenon is likely to occur when the surface potential of the element portion increases and a large difference in the surface potential between the elements easily occurs. Further, it is likely to occur when the voltage applied to the anode electrode for extracting the emitted electrons is increasing. That is, by suppressing the rise in the surface potential over a large number of elements, it is possible to stabilize the trajectory of the emitted electrons and effectively suppress the discharge.
[0011]
Conventionally, for example, in Japanese Patent Application Laid-Open No. 1-283735, in order to stabilize the trajectory of the emitted electrons, a method of providing a potential regulating means near an electron-emitting device to regulate the surface potential of the insulating substrate is described. However, when an electrode as a potential regulating means is formed on the upper surface of the substrate and is used as an electron source using a plurality of surface conduction electron-emitting devices, a plurality of wirings or a potential It has been difficult to form the defining electrode pattern over a large area with good yield.
[0012]
Although it is conceivable to form an electrode for regulating the potential on the lower surface of the substrate, it is difficult to sufficiently suppress the rise in the surface potential when the thickness of the substrate is increased in response to an increase in area. . For example, when an insulating glass having a relative dielectric constant of about 5 and a thickness of 2 mm is used, the voltage applied to the potential regulating electrode is the ground voltage, the distance between the substrate and the anode is 5 mm, and the anode is applied. By setting the voltage to 10 kV, the surface potential calculated from the capacitance division increases to several hundred volts. This is a value that is at least 10 times larger than the driving voltage of the element of about 20 V, makes the trajectory of the emitted electrons unstable, and does not provide a sufficient effect for suppressing the discharge.
[0013]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface conduction electron-emitting device having a low cost, easily having a large area, and having stable electron emission characteristics, and an electron source device using the same. More specifically, it is an object of the present invention to provide an electron source device in which the discharge phenomenon is effectively suppressed.
[0014]
[Means for Solving the Problems]
The present invention has been made by intensive studies in order to solve the above-described problems, and has the following configuration.
[0015]
That is, the present invention Multiple electron-emitting devices are arranged substrate And the plurality of electron-emitting devices Up One To Placed Anode electrode When In the electron source having Between the substrate and the plurality of electron-emitting devices, a conductive layer defined at a ground potential, and an insulating layer that insulates between the conductive layer and the plurality of electron-emitting devices are arranged. The insulating layer is formed of the insulating layer. Surface potential Has a thickness that is not more than the maximum value of the potential applied to the electron-emitting device. An electron source characterized by the following, and said electron And an image forming member An image forming apparatus.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
First, an electron source using a surface conduction electron-emitting device will be described.
[0018]
FIGS. 1A and 1B are schematic diagrams showing the configuration of an electron source using a surface conduction electron-emitting device to which the present invention can be applied. FIG. 1A is a plan view, and FIG. FIG.
[0019]
In FIG. 1, 1 is a composite substrate, 2 and 3 are device electrodes, 4 is a conductive thin film, 5 is an electron-emitting portion, 72 is an X-direction wiring, and 73 is a Y-direction wiring. One composite substrate is composed of six substrates, a conductive layer 7 and an insulating layer 8. Also, B and B 'in the figure indicate alignment positions to be described later. The surface conduction electron-emitting device includes a conductive thin film 4 having an electron-emitting portion 5 and a pair of device electrodes 2 and 3.
[0020]
As the substrate 6, quartz glass, glass having a reduced impurity content such as Na, blue plate glass, ceramics such as alumina, or a Si substrate can be used.
[0021]
As the material of the conductive layer 7, the X-directional wiring 72, the Y-directional wiring 73, and the element electrodes 2 and 3 facing each other, general conductive materials can be used. This is, for example, a metal or alloy such as Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu, Pd and Pd, Ag, Au, RuO. ₂ , Pd-Ag, etc., a metal or metal oxide and a printed conductor composed of glass, etc., In ₂ O ₃ -SnO ₂ And the like, and a semiconductor conductor material such as polysilicon and the like.
[0022]
The insulating layer 8 is made of SiO ₂ , SiN, PSG (phosphorus-doped glass) or the like can be used. The type and thickness of the insulating layer 8 determine the capacitance between the conductive layer 7 and the element surface, suppress the rise in surface potential, and prevent a large difference in surface potential between elements. It can be appropriately selected to suppress and prevent discharge. For example, the voltage applied to the potential regulating electrode (not shown) connected to the conductive layer 7 is the ground voltage, the driving potential is 20 V, the distance between the anode and the substrate is 5 mm, and the dielectric constant ε1 of the insulating layer 8 is When the ratio ε1 / ε2 of the dielectric constant ε2 between the anode and the substrate is 5, the thickness of the insulating layer 8 is set to about 0.05 mm or less so that the anode applied voltage is 10 kV or less and the surface potential rises. It is possible to keep the driving voltage or lower. This is because the thickness of the insulating layer 8 as the second layer is d1, the dielectric constant of the insulating layer is ε1, the distance between the surface conduction electron-emitting device and the anode is d2, and the distance between the surface conduction electron-emitting device and the anode is d2. When the dielectric constant of is ε2 and the voltage applied to the anode is V1, the following equation
V2 = V1 / (1+ (d2 × ε1) / (d1 × ε2))
This is because the value of V2 represented by represents the surface potential obtained from the capacitance division.
[0023]
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 applied form and the like. The element electrode interval L can be preferably in the range of several hundred nm to several hundred μm, and more preferably in the range of several μm to several tens μm.
[0024]
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 can be in the range of several tens nm to several μm.
[0025]
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, a forming condition described later, and the like. It is preferably in the range of several hundred nm, more preferably in the range of 1 nm to 50 nm. The sheet resistance value Rs is 10 ² From Ω / □ to 10 ⁷ Ω / □. In the specification of the present application, the forming process will be described by taking an energizing process as an example, but the forming process is not limited to this, and includes a process of forming a crack in a film to form a high resistance state. It is.
[0026]
Materials forming the conductive thin film 4 include metals such as Pd, Pt, Ru, Au, Ti, In, Cu, Cr, Fe, Zn, Sn, Ta, W, and Pd, PdO, and SnO. ₂ , In ₂ O ₃ , PbO, Sb ₂ O ₃ Oxides such as HfB ₂ , ZrB ₂ , LaB ₆ , CeB ₆ , YB ₄ , GdB ₄ And the like, carbides such as TiC, ZrC, HfC, Ta, C, SiC and WC, nitrides such as TiN, ZrN and HfN, semiconductors such as Si and Ge, carbon and the like.
[0027]
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 in which the fine particles are individually dispersed and arranged, or in a state in which the fine particles are adjacent to each other or overlapped (some fine particles are gathered, (Including the case where an island structure is formed as a whole). The particle size of the fine particles is in the range of several times to several hundreds of nm, preferably in the range of 1 nm to 20 nm.
[0028]
In the present specification, the term “fine particles” is frequently used, and the meaning will be described.
[0029]
Small particles are called "fine particles" and smaller ones are called "ultra fine particles". It is widely practiced to call a “cluster” a particle that is smaller than “ultrafine particles” and has a few hundred atoms or less.
[0030]
However, each boundary is not strict and changes depending on what kind of property is focused on. In addition, “fine particles” and “ultrafine particles” may be collectively referred to as “fine particles”, and the description in this specification is in line with this.
[0031]
"Experimental Physics Course 14: Surfaces and Particles" (edited by Kinoshita Yoshio, published by Kyoritsu Shuppan, September 1, 1986) states as follows.
[0032]
"In this paper, the term" fine particles "refers to a particle diameter of about 2 to 3 μm to about 10 nm, and the term" ultrafine particles "refers to a particle diameter of about 10 nm to about 2 to 3 nm. It is not a strict one because it is simply written as a fine particle, and it is a rough guide. When the number of atoms constituting a particle is two to several tens to several hundreds, it is called a cluster. "(Page 195) (Lines 22-26)
In addition, the definition of "ultra-fine particles" in the "Hayashi and Ultra-fine Particle Project" of the New Technology Development Corporation has a lower minimum particle size, as follows.
[0033]
"In the" Ultra Fine Particle Project "of the Creative Science and Technology Promotion System (1981 to 1986), particles with a size (diameter) in the range of about 1 to 100 nm are called" ultra fine particles ". Then, one ultrafine particle is about 10 ⁰ -10 ⁸ It is an aggregate of about atoms. Ultra-fine particles are large to giant particles on an atomic scale. ("Ultrafine Particles, Creative Science and Technology" Hayashi Tax, Ryoji Ueda, Akira Tazaki, ed., Mita Publishing, 1988, page 2, lines 1 to 4) "Even smaller than ultrafine particles, that is, several to several hundred atoms. A single structured particle is usually called a cluster. ”(Page 2, lines 12 to 13 of the same book) Based on the general term as described above,“ fine particles ”in the present specification refers to a large number of atoms. A molecular aggregate having a lower limit of a particle size from several times 0.1 nm to about 1 nm and an upper limit of about several μm.
[0034]
The electron-emitting portion 5 is constituted by a high-resistance crack formed in a part of the conductive thin film 4 and depends on a thickness, a film quality, a material of the conductive thin film 4, a method such as energization forming described later, and the like. Become. In some cases, conductive fine particles having a particle diameter in the range of several times 0.1 nm to several tens nm are present inside the electron emission 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.
[0035]
There are various methods for manufacturing the above-described electron source of the surface conduction electron-emitting device. One example is schematically shown in FIGS.
[0036]
Hereinafter, an example of the manufacturing method will be described with reference to FIG. 1, FIG. 3, and FIG. 3 and 4, the same parts as those shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG.
[0037]
1) The substrate 6 is sufficiently washed with a detergent, pure water, an organic solvent, and the like, and a conductive layer 7 is formed by a vacuum evaporation method, a sputtering method, or the like (FIG. 3A). If necessary, the conductive layer 7 may be processed into a desired shape by using, for example, a photolithography technique.
[0038]
2) After forming a conductive layer 7 on a substrate 6, an insulating layer 8 is formed by a CVD method or a sputtering method (FIG. 3B).
[0039]
3) After a device electrode material is deposited on the composite substrate 1 on which the conductive layer 7 and the insulating layer 8 are formed on the substrate 6 by a vacuum deposition method, a sputtering method, or the like, the element is formed on the composite substrate 1 by using, for example, a photolithography technique. The electrodes 2 and 3 are formed (FIG. 3C). In addition, as a forming method, a method using a printing technique by a thick film method can be adopted.
[0040]
4) A Y-directional wiring 73 is formed on the composite substrate 1 provided with the device electrodes 2 and 3. After forming a film using a vacuum deposition method or the like, a method using a photolithography technique or a method using a printing technique using a thick film method can be adopted (FIG. 3D).
[0041]
5) An interlayer insulating layer 9 is formed at a portion where the X-direction wiring and the Y-direction wiring intersect (not shown in FIG. 3).
[0042]
6) The X-direction wiring 72 is formed in the same manner as in 4) (FIG. 3E).
[0043]
7) An organometallic solution is applied to form an organometallic thin film. As the organometallic solution, a solution of an organometallic compound containing the metal of the material of the conductive thin film 4 as a main element can be used. 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 (FIG. 4F). Here, the method of applying the organic metal solution has been described. The method of forming the thin film 4 is not limited to the above, but may be a vacuum evaporation method, a sputtering method, a chemical vapor deposition method, a dispersion coating method, a dipping method, a spinner method, or a bubble-jet type inkjet ejecting apparatus. And the like.
[0044]
8) Subsequently, a forming step is performed. As an example of the method of the forming step, a method by an energization process will be described. When an electric current is applied between the X-directional wiring 72 and the Y-directional wiring 73 using a power supply (not shown), an electron emitting portion 5 having a changed structure is formed at the portion of the conductive thin film 4 (FIG. 4 (g)). )). The way of energizing the x-direction wiring 72 and the y-direction wiring 73 will be described later. According to the energization forming, a portion where the structure such as destruction, deformation or alteration is locally formed in the conductive thin film 4 is formed. This portion constitutes the electron emission section 5. FIG. 5 shows an example of the voltage waveform of the energization forming.
[0045]
The voltage waveform is preferably a pulse waveform. The method shown in FIG. 5A in which a pulse with a constant pulse height is applied as a constant voltage and the method shown in FIG. 5B in which a voltage pulse is applied while increasing the pulse peak value are used for this purpose. There is.
[0046]
T1 and T2 in FIG. 5A are the pulse width and pulse interval of the voltage waveform. Usually, T1 is set in the range of 1 μsec to 10 msec, and T2 is set in the range of 10 μsec to 10 msec. The peak value of the triangular wave (peak voltage at the time of energization forming) is appropriately selected according to the surface conduction electron-emitting device configuration. Under such conditions, for example, a voltage is applied for several seconds to several tens minutes. The pulse waveform is not limited to a triangular wave, and a desired waveform such as a rectangular wave can be adopted.
[0047]
T1 and T2 in FIG. 5B can be the same as those shown in FIG. 5A. The peak value of the triangular wave (peak voltage during energization forming) can be increased, for example, by about 0.1 V / step.
[0048]
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 4 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 a resistance of 1 MΩ or more per element is indicated, the energization forming is terminated.
[0049]
9) It is preferable to perform a process called an activation step on the device after the forming. The activation process is a process in which the device current If and the emission current Ie are significantly changed by this process. The activation step 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 can be formed by using an organic gas remaining in the atmosphere when the inside of the vacuum vessel is evacuated using, for example, an oil diffusion pump or a rotary pump, or 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. Examples of suitable organic substances include aliphatic hydrocarbons such as alkanes, alkenes, and alkynes, aromatic hydrocarbons, alcohols, aldehydes, ketones, amines, and organic acids such as phenol, carboxylic acid, and sulfonic acid. And specifically, C, methane, ethane, propane, etc. _n H _{2n + 2} C, such as saturated hydrocarbons, ethylene and propylene represented by _n H _2n Unsaturated hydrocarbon, benzene, toluene, methanol, ethanol, formaldehyde, acetaldehyde, acetone, methyl ethyl ketone, methylamine, ethylamine, phenol, formic acid, acetic acid, propionic acid, etc., or a mixture thereof can be used. . By this treatment, carbon or a carbon compound is deposited on the device from the organic substance existing in the atmosphere, and the device current If and the emission current Ie are significantly changed.
[0050]
The end of the activation step is determined as appropriate while measuring the device current If and the emission current Ie. Note that the pulse width, pulse interval, pulse crest value, and the like are set as appropriate.
[0051]
Carbon and carbon compounds include, for example, graphite (including so-called HOPG, PG, and GC, HOPG is a crystal structure of almost perfect graphite, PG is a crystal having a crystal grain of about 200 ° and a crystal structure is slightly disordered, and GC is a crystal. Grains having a grain size of about 20 ° and disorder in the crystal structure are further increased), and amorphous carbon (indicating amorphous carbon and a mixture of amorphous carbon and the microcrystals of graphite). The range is preferably 50 nm or less, and more preferably 30 nm or less.
[0052]
10) The electron-emitting device obtained through such a step is preferably subjected to a stabilization step. This step is a step of exhausting the organic substance in the vacuum container. It is preferable to use a vacuum evacuation 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.
[0053]
In the activation step, 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 or the rotary pump is used, the partial pressure of this component needs to be suppressed as low as possible. The partial pressure of the organic component in the vacuum vessel is 1.3 × 10 3 at which the above-mentioned carbon and carbon compounds hardly newly deposit. ^-6 Pa or less, more preferably 1.3 × 10 ^-8 Pa or less is particularly preferred. Further, when the inside of the vacuum vessel is evacuated, it is preferable that the entire vacuum vessel is heated so that the organic substance molecules adsorbed on the inner wall of the vacuum vessel and the electron-emitting device are easily evacuated. The heating conditions at this time are desirably 80 to 250 ° C., preferably 150 ° C. or higher, and it is desirable to perform the treatment as long as possible. However, the present invention is not particularly limited to this condition, and the size and shape of the vacuum vessel, the configuration of the electron-emitting device, The conditions are appropriately selected according to the above conditions. The pressure in the vacuum vessel needs to be as low as possible. ^-5 Pa or less, more preferably 1.3 × 10 ^-6 Pa or less is particularly preferred.
[0054]
The atmosphere at the time of driving after performing the stabilization step is preferably the same as the atmosphere at the end of the stabilization treatment, but is not limited to this. If the organic substance is sufficiently removed, the vacuum Even if it is slightly reduced, sufficiently stable characteristics can be maintained.
[0055]
By adopting such a vacuum atmosphere, the deposition of new carbon or a carbon compound can be suppressed, and H ₂ O, O ₂ Can be removed, and as a result, the element current If and the emission current Ie are stabilized.
[0056]
The basic characteristics of the electron source to which the present invention obtained through the above-described steps is applicable will be described. First, the characteristics of a single electron-emitting device that can constitute an electron source to which the present invention can be applied will be described with reference to FIGS.
[0057]
FIG. 6 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. 6, the same parts as those shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG. In FIG. 6, 55 is a vacuum vessel, and 56 is an exhaust pump. An electron source is provided in the vacuum vessel 55. That is, reference numeral 1 denotes a composite substrate constituting an electron source, which is composed of a substrate 6, a conductive layer 7, and an insulating layer 8. Reference numerals 2 and 3 denote device electrodes, 4 denotes a conductive thin film, and 5 denotes an electron emitting portion. 51 is a power supply for applying a device voltage Vf to the electron-emitting device, 50 is an ammeter for measuring a device current If flowing through the conductive thin film 4 between the device electrodes 2 and 3, and 54 is an electron-emitting portion of the device. An anode electrode for capturing the emission current Ie emitted from the anode. 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. As an example, the measurement can be performed with the voltage of the anode electrode 54 in the range of 1 kV to 10 kV and the distance H between the anode electrode 54 and the electron-emitting device in the range of 2 mm to 8 mm. The conductive layer 7 can be connected to a power supply (not shown), and can apply a voltage. In particular, the voltage applied to the conductive layer 7 can be a ground voltage. In this case, a power supply or the like for applying a voltage to the conductive layer 7 is not required, and this is particularly preferable. As described above, the thickness of the insulating layer 8 as the second layer is d1, the dielectric constant of the insulating layer is ε1, the distance between the surface conduction electron-emitting device and the anode 54 is d2, and the surface conduction electron-emitting device is When the dielectric constant between the anode and the anode 54 is ε2 and the anode applied voltage is V1, the following equation
V2 = V1 / (1+ (d2 × ε1) / (d1 × ε2))
By designing the value of V2 represented by the following equation to be equal to or less than the maximum value of the potential applied to the electron-emitting device, it is possible to particularly effectively suppress an increase in the surface potential.
[0058]
In the vacuum vessel 55, devices necessary for measurement in a vacuum atmosphere such as a vacuum gauge (not shown) are provided so that measurement and evaluation in a desired vacuum atmosphere can be performed. The exhaust pump 56 is composed of 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 to 250 ° C. by a heater (not shown). Therefore, when this vacuum processing apparatus is used, the steps after the above-described energization forming can also be performed.
[0059]
FIG. 7 is a diagram schematically showing the relationship between the emission current Ie, the device current If, and the device voltage Vf measured using the vacuum processing apparatus shown in FIG. In FIG. 7, 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.
[0060]
As is clear from FIG. 7, 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.
[0061]
That is,
(I) In this device, the emission current Ie sharply increases when a device voltage higher than a certain voltage (referred to as a threshold voltage, Vth in FIG. 7) is applied, whereas when the device voltage is lower than the threshold voltage Vth, the emission current Ie decreases. Hardly detected. That is, it is a nonlinear element having a clear threshold voltage Vth with respect to the emission current Ie.
[0062]
(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.
[0063]
(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.
[0064]
As will be understood from the above description, the surface conduction electron-emitting device that can constitute 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. become. By utilizing this property, it is possible to apply to various fields such as an electron source and an image forming apparatus having a plurality of electron-emitting devices.
[0065]
In FIG. 7, 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 (not shown). These characteristics can be controlled by controlling the aforementioned steps.
[0066]
Next, an electron source or an image forming apparatus to which the present invention can be applied, in which a plurality of surface conduction electron-emitting devices are arranged on a substrate, will be described.
[0067]
Various arrangements of the electron-emitting devices can be adopted.
[0068]
As an example, each of a large number of electron-emitting devices arranged in parallel is connected at both ends, a large number of rows of electron-emitting devices are arranged (referred to as a row direction), and a direction perpendicular to the wiring (referred to as a column direction). There is a ladder-like arrangement in which electrons from the electron-emitting devices are controlled and driven by control electrodes (also called grids) arranged above the electron-emitting devices. Separately, a plurality of electron-emitting devices are arranged in a matrix in the X and Y directions, and one of the electrodes of the plurality of electron-emitting devices arranged in the same row is commonly connected to a wiring in the X direction. One in which the other of the electrodes of a plurality of electron-emitting devices arranged in the same column is commonly connected to a wiring in the Y direction. This is a so-called simple matrix arrangement. First, the simple matrix arrangement will be described in detail below.
[0069]
The surface conduction electron-emitting device applicable to the present invention has characteristics (i) to (iii) as described above. That is, when the electron emission from the surface conduction electron-emitting device is equal to or higher than the threshold voltage, it can be controlled by the peak value and the width of the pulse voltage applied between the opposing device electrodes. On the other hand, when the voltage is equal to or lower than the threshold voltage, almost no emission occurs. 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 quantity.
[0070]
Hereinafter, based on this principle, an electron source substrate obtained by disposing a plurality of electron-emitting devices to which the present invention can be applied will be described with reference to FIG. 8, reference numeral 71 denotes an electron source substrate, 72 denotes an X-direction wiring, and 73 denotes a Y-direction wiring. 74 is a surface conduction electron-emitting device, and 75 is a connection. The electron source substrate 71 includes the substrate 6, the conductive layer 7, the insulating layer 8, and the like in FIG.
[0071]
The m X-directional wirings 72 are made of Dx1, Dx2,..., Dxm, and can be made of a conductive metal or the like formed using 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 73 includes n wirings Dy1, Dy2,..., Dyn, and is formed in the same manner as the X-direction wiring 72. An interlayer insulating layer (not shown) is provided between the m X-directional wirings 72 and the n Y-directional wirings 73 to electrically separate them (m and n are both Positive integer).
[0072]
The interlayer insulating layer 8 (not shown) is formed of SiO 2 formed by a vacuum evaporation method, a printing method, a sputtering method, or the like. ₂ Etc. For example, it is formed in a desired shape on the entire surface or a part of the substrate 71 on which the X-directional wiring 72 is formed. The material and manufacturing method are appropriately set. The X-direction wiring 72 and the Y-direction wiring 73 are led out as external terminals.
[0073]
A pair of electrodes (2 and 3 in FIG. 2) constituting the surface conduction electron-emitting device 74 are electrically connected to the m X-directional wires 72 and the n Y-directional wires 73 by a connection 75 made of a conductive metal or the like. It is connected to the.
[0074]
The material forming the wiring 72 and the wiring 73, the material forming the connection 75, and the material forming the pair of device 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. When the material forming the element electrode and the wiring material are the same, the wiring connected to the element electrode can also be called an element electrode.
[0075]
A scanning signal applying unit (not shown) for applying a scanning signal for selecting a row of the surface conduction electron-emitting devices 74 arranged in the X direction is connected to the X-direction wiring 72. On the other hand, the Y-direction wiring 73 is connected to a modulation signal generating means (not shown) for modulating each column of the surface conduction electron-emitting devices 74 arranged in the Y direction according to an input signal. 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.
[0076]
In the above configuration, individual elements can be selected and driven independently using simple matrix wiring.
[0077]
A ground voltage may be applied to the conductive layer 7 constituting the electron source substrate 71. However, in consideration of the capacitance ε1 determined by the material and the thickness of the insulating layer 8, it is necessary to obtain a desired surface potential. Voltage can also be applied. When the above-mentioned capacitance ε1 is large and it is difficult to obtain a desired driving voltage under a desired driving condition, the conductive layer 7 is mainly formed in a portion of the element surface facing the insulating surface, and the X-direction wiring 72 is formed. The conductive layer 7 may not be formed as much as possible in the portion facing the Y-directional wiring 73, the device electrodes 2 and 3, and the conductive thin film 4.
[0078]
An image forming apparatus configured using such an electron source having a simple matrix arrangement will be described with reference to FIGS. 9, 10, and 11. FIG. FIG. 9 is a schematic diagram illustrating an example of a display panel of the image forming apparatus, and FIG. 10 is a schematic diagram of a fluorescent film used in the image forming apparatus of FIG. FIG. 11 is a block diagram illustrating an example of a driving circuit for performing display according to an NTSC television signal.
[0079]
9, reference numeral 71 denotes an electron source substrate on which a plurality of electron-emitting devices are arranged; 81, a rear plate on which the electron source substrate 71 is fixed; 86, a face on which a fluorescent film 84 and a metal back 85 are formed on the inner surface of a glass substrate 83; Plate. A support frame 82 has a rear plate 81 and a face plate 86 joined to the support frame 82 by using low melting point frit glass or the like.
[0080]
Reference numeral 74 denotes a surface conduction electron-emitting device. Reference numerals 72 and 73 denote an X-direction wiring and a Y-direction wiring connected to a pair of device electrodes of the surface conduction electron-emitting device.
[0081]
The envelope 88 includes the face plate 86, the support frame 82, and the rear plate 81 as described above. Since the rear plate 81 is provided mainly for the purpose of reinforcing the strength of the substrate 71, if the substrate 71 itself has sufficient strength, the separate rear plate 81 can be unnecessary. That is, the support frame 82 may be directly sealed to the substrate 71, and the envelope 88 may be configured by the face plate 86, the support frame 82, and the substrate 71. On the other hand, by providing a support (not shown) called a spacer between the face plate 86 and the rear plate 81, an envelope 88 having sufficient strength against atmospheric pressure can be formed.
[0082]
FIG. 10 is a schematic diagram showing a fluorescent film. The fluorescent film 84 can be composed of only a phosphor in the case of monochrome. In the case of a color fluorescent film, it can be composed of a black conductive material 91 called a black stripe or a black matrix and a fluorescent material 92 depending on the arrangement of the fluorescent materials. The purpose of providing the black stripes and the black matrix is to make the color separation between the phosphors 92 of the necessary three primary color phosphors black in the case of color display so that color mixing and the like become inconspicuous. It is to suppress a decrease in contrast due to light reflection. As the material of 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.
[0083]
As a method of applying the phosphor onto the glass substrate 83, a precipitation method, a printing method, or the like can be adopted regardless of monochrome or color. Usually, a metal back 85 is provided on the inner surface side of the fluorescent film 84. The purpose of providing the metal back is to improve the luminance by mirror-reflecting light toward the inner surface side of the phosphor emission toward the face plate 86 side, to act as an electrode for applying an electron beam acceleration voltage, The purpose is to protect the phosphor from damage due to collision of negative ions generated in the envelope. The metal back can be manufactured by performing a smoothing treatment (usually called “filming”) on the inner surface of the fluorescent film after the fluorescent film is manufactured, and then depositing Al using vacuum evaporation or the like.
[0084]
The face plate 86 may be provided with a transparent electrode (not shown) on the outer surface side of the fluorescent film 84 in order to further increase the conductivity of the fluorescent film 84.
[0085]
When performing the above-described sealing, in the case of color, it is necessary to make each color phosphor correspond to the electron-emitting device, and sufficient alignment is indispensable.
[0086]
An example of a method for manufacturing the image forming apparatus shown in FIG. 9 will be described below.
[0087]
FIG. 14 is a schematic view showing an outline of an apparatus used in this step. The image forming apparatus 131 is connected to a vacuum chamber 133 via an exhaust pipe 132, and is further connected to an exhaust apparatus 135 via a gate valve. The vacuum chamber 133 is provided with a pressure gauge 136, a quadrupole mass analyzer (Q-mass) 137, and the like in order to measure the internal pressure and the partial pressure of each component in the atmosphere. Since it is difficult to directly measure the pressure and the like inside the envelope 88 of the image display device 131, the pressure and the like inside the vacuum chamber 133 are measured to control the processing conditions.
[0088]
A gas introduction line 138 is connected to the vacuum chamber 133 to introduce necessary gas into the vacuum chamber to control the atmosphere. An introduction substance source 140 is connected to the other end of the gas introduction line 138, and the introduction substance is stored in an ampule 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 the introduction amount control means, specifically, a valve such as a slow leak valve capable of controlling the 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.
[0089]
The inside of the envelope 88 is evacuated by the apparatus shown in FIG. 14 to perform forming. At this time, for example, as shown in FIG. 15, the Y-direction wiring 73 is connected to the common electrode 141, and a voltage pulse is simultaneously applied by a power source 142 to an element connected to one of the X-direction wirings 72. Forming can be performed. 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 element. Also, 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.
[0090]
After the forming is completed, an activation step is performed. After sufficiently exhausting the inside of the envelope 88, the organic substance is introduced from the gas introduction line 138. Alternatively, as described in the method of activating the individual elements, first, the gas may be exhausted by an oil diffusion pump or a rotary pump, and the organic substance remaining in the vacuum atmosphere may be used. In addition, substances other than organic substances may be introduced as necessary. By applying a voltage to each electron-emitting device in an atmosphere containing an organic substance formed in this manner, carbon or a carbon compound, or a mixture of both, is deposited on the electron-emitting portion, and the amount of emitted electrons is drastic. Is similar to the case of the individual element. In this case, the voltage may be applied by simultaneously applying a voltage pulse to the elements connected to one direction wiring by the same connection as in the above-described forming.
[0091]
After the completion of the activation step, it is preferable to perform a stabilization step as in the case of the individual element.
[0092]
After heating the envelope 88 and keeping it at 80 to 250 ° C., the exhaust gas is exhausted through the exhaust pipe 132 by an exhaust device 135 that does not use oil, such as an ion pump or a sorption pump, to obtain an atmosphere containing a sufficiently small amount of organic substances. Then, the exhaust pipe 132 is heated and melted by a burner and sealed. To maintain the pressure after the envelope 88 is sealed, a getter process may be performed. This is because the getter arranged at a predetermined position (not shown) in the envelope 88 is heated by heating using resistance heating or high-frequency heating immediately before or after the envelope 88 is sealed. This is a process for forming a deposited film. The getter is usually composed mainly of Ba or the like, and maintains the atmosphere in the envelope 88 by the adsorption action of the deposited film.
[0093]
Next, an example of the configuration of a driving circuit for performing television display based on an NTSC television signal on a display panel configured using electron sources in a simple matrix arrangement will be described with reference to FIG. In FIG. 11, 101 is an image display panel, 102 is a scanning circuit, 103 is a control circuit, and 104 is a shift register. 105 is a line memory, 106 is a synchronizing signal separation circuit, 107 is a modulation signal generator, and Vx and Va are DC voltage sources.
[0094]
The display panel 101 is connected to an external electric circuit via terminals Dox1 to Doxm, terminals Doy1 to Doyn, and a high-voltage terminal Hv. Terminals Dox1 to Doxm are used to sequentially drive 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, one row (N elements) at a time. Are applied.
[0095]
To the terminals Dy1 to Dyn, a modulation signal for controlling an output electron beam of each element of the surface conduction electron-emitting device in one row selected by the scanning signal 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 gives an electron beam emitted from the surface conduction electron-emitting device sufficient energy to excite the phosphor. This is the acceleration voltage for performing
[0096]
The scanning circuit 102 will be described. This circuit includes M switching elements inside (in the drawing, 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 is electrically connected to the terminals Dx1 to Dxm of the display panel 101. Each of the switching elements S1 to Sm outputs a control signal T output from the control circuit 103. _SCAN , And can be configured by combining switching elements such as FETs, for example.
[0097]
In the case of the present embodiment, the DC voltage source Vx determines that the driving voltage applied to the unscanned element is equal to or lower than the electron emission threshold voltage based on the characteristics (electron emission threshold voltage) of the surface conduction electron emission element. It is set to output such a constant voltage.
[0098]
The control circuit 103 has a function of matching the operation of each unit so that appropriate display is performed based on an image signal input from the outside. The control circuit 103 controls the synchronization signal T sent from the synchronization signal separation circuit 106. _SYNC T for each part based on _SCAN And T _SFT And T _MRY Are generated.
[0099]
The synchronization signal separation circuit 106 is a circuit for separating a synchronization signal component and a luminance signal component from an NTSC television signal input from the outside. The synchronizing signal separated by the synchronizing signal separating circuit 106 includes 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 104.
[0100]
The shift register 104 is for serially / parallel-converting the DATA signal input serially in time series for each line of an image, and a control signal T sent from the control circuit 103. _SFT (Ie, the control signal T _SFT Is the shift clock of the shift register 104. ). Data of one line of an image (corresponding to drive data for N electron-emitting devices) that has been subjected to serial / parallel conversion is output from the shift register 104 as N parallel signals Id1 to Idn.
[0101]
The line memory 105 is a storage device for storing data for one line of an image for a necessary time only, and a control signal T sent from the control circuit 103. _MRY , The contents of Id1 to Idn are stored as appropriate. The stored contents are output as I'd1 to I'dn and input to the modulation signal generator 107.
[0102]
The modulation signal generator 107 is a signal source for appropriately driving and modulating each of the surface conduction electron-emitting devices in accordance with each of the image data I'd1 to I'dn. The voltage is applied to the surface conduction electron-emitting device in the display panel 101 through Doyn.
[0103]
As described above, the electron-emitting device to which the present invention can be applied 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 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 this 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 emitted. Is output. At this 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.
[0104]
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 adopted. When implementing the voltage modulation method, a circuit of the voltage modulation method that generates a voltage pulse of a fixed length and modulates the peak value of the pulse appropriately according to input data is used as the modulation signal generator 107. be able to.
[0105]
When 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 circuit can be used.
[0106]
As the shift register 104 and the line memory 105, either a digital signal type or an analog signal type can be used. This is because the serial / parallel conversion and storage of the image signal may be performed at a predetermined speed.
[0107]
When the digital signal type is used, it is necessary to convert the output signal DATA of the synchronization signal separation circuit 106 into a digital signal. For this purpose, an A / D converter may be provided at the output of the synchronization signal separation circuit 106. In this connection, the circuit used for the modulation signal generator 107 is slightly different 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, for example, a D / A conversion circuit is used as the modulation signal generator 107, and an amplification circuit and the like are added as necessary. In the case of the pulse width modulation method, the modulation signal generator 107 includes, for example, a high-speed oscillator, a counter for counting the number of waves output from the oscillator, and a comparator for comparing the output value of the counter with the output value of the memory. (Comparator) is 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.
[0108]
In the case of a voltage modulation method using an analog signal, for example, an amplification circuit using an operational amplifier or the like can be employed 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 (VOC) can be adopted, and an amplifier for amplifying the voltage up to the driving voltage of the surface conduction electron-emitting device can be added if necessary.
[0109]
In the image display device to which the present invention can be applied, an electron emission is generated by applying a voltage to each of the electron-emitting devices via the external terminals Dox1 to Doxm and Doy1 to Doyn. 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 and emit light to form an image.
[0110]
Next, the ladder-type arrangement of the electron source and the image forming apparatus will be described with reference to FIGS.
[0111]
FIG. 12 is a schematic diagram illustrating an example of an electron source having a ladder-type arrangement. In FIG. 12, reference numeral 110 denotes an electron source substrate, and 111 denotes an electron-emitting device. Note that the electron source substrate 110 includes the substrate 6, the conductive layer 7, the insulating layer 8, and the like. Dx1 to Dx10 indicated by 112 are common wirings for connecting the electron-emitting devices 111. A plurality of electron-emitting devices 111 are arranged on the substrate 110 in parallel in the X direction (this is called an element row). A plurality of these element rows are arranged to constitute an electron source. By applying a drive voltage between the common wires of each element row, each element row can be driven independently. That is, a voltage equal to or higher than the electron emission threshold is applied to an element row that wants to emit an electron beam, and a voltage equal to or lower than the electron emission threshold is applied to an element row that does not emit an electron beam. As for the common wirings Dx2 to Dx9 between the element rows, for example, Dx2 and Dx3 can be the same wiring.
[0112]
FIG. 13 is a schematic diagram illustrating an example of a panel structure in an image forming apparatus including a ladder-type electron source. Reference numeral 120 denotes a grid electrode, 121 denotes a hole through which electrons pass, and 122 denotes an external terminal made of Dox1, Dox2,..., Doxm. Reference numeral 123 denotes an external terminal composed of G1, G2,..., Gn connected to the grid electrode 120. In FIG. 13, the same parts as those shown in FIGS. 9 and 12 are denoted by the same reference numerals as those shown in these figures. A major difference between the image forming apparatus shown here and the image forming apparatus having the simple matrix arrangement shown in FIG. 9 is whether or not the grid electrode 120 is provided between the electron source substrate 110 and the face plate 86.
[0113]
In FIG. 13, a grid electrode 120 is provided between the substrate 110 and the face plate 86. The grid electrode 120 is for modulating the electron beam emitted from the surface conduction electron-emitting device, and allows the electron beam to pass through a stripe-shaped electrode provided orthogonal to the ladder-type element row. One circular opening 121 is provided for each element. The shape and installation position of the grid are not limited to those shown in FIG. For example, a large number of passage openings may be provided in the form of a mesh as openings, and a grid may be provided around or near the surface conduction electron-emitting device.
[0114]
The outer container terminal 122 and the grid outer terminal 123 are electrically connected to a control circuit (not shown).
[0115]
In the image forming apparatus of this embodiment, a modulation signal for one line of an image is simultaneously applied to the grid electrode columns in synchronization with sequentially driving (scanning) the element rows one by one. Thus, irradiation of each electron beam to the phosphor can be controlled, and an image can be displayed line by line.
[0116]
The configuration of the image forming apparatus 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. As for the input signal, the NTSC method has been described, but the input signal is not limited to this. For example, a PAL, SECAM method, or other TV signal (for example, high-definition TV) comprising a larger number of scanning lines may be used. Can also be adopted.
[0117]
In addition, the image forming apparatus described here may be used as a display device for a television broadcast, a display device such as a video conference system or a computer, or an image forming device as an optical printer configured using a photosensitive drum or the like. Can be used.
[0118]
The electron source and the image forming apparatus of the present invention are characterized by having a conductive layer 7 and an insulating layer 8, which is provided between the conductive layer 7 determined by the material and thickness of the insulating layer 8 and the element forming surface. The purpose is to specify the capacitance. Accordingly, when a common voltage is applied to each electron-emitting device to the conductive layer 7 with respect to the voltage applied to the anode electrode 54, it is possible to define the surface potential of each element formation surface. Become. That is, in the electron source of the present invention, not only the trajectory of the emitted electrons is stable, but also the electron source can be driven stably for a long time. More specifically, it is possible to suppress a rise in the surface potential of the element portion and a discharge phenomenon caused when a difference is easily generated in the surface potential between the elements.
[0119]
In the electron source of the present invention, when the voltage applied to the conductive layer 7 as the first layer is a ground voltage, the thickness of the insulating layer as the second layer is d1, the dielectric constant of the insulating layer is ε1, When the distance between the surface conduction electron-emitting device and the anode is d2, the dielectric constant between the surface conduction electron-emitting device and the anode is ε2, and the voltage applied to the anode is V1, the following expression is used.
V2 = V1 / (1+ (d2 × ε1) / (d1 × ε2))
When the value of the voltage V2 represented by the following expression is equal to or less than the driving voltage, it is possible to drive stably especially for a long time, and at the same time, it is possible to effectively perform a discharge that easily occurs when the voltage applied to the anode is increasing. Can be suppressed. The value of the voltage V2 represents the surface potential of the element type surface calculated from the capacitance division, and can be variously changed by controlling the above-described d2, d1, and ε1. It should be noted that ε2 is approximately represented by a dielectric constant in a vacuum, and it is difficult to control ε2.
[0120]
For example, the voltage applied to the conductive layer 7 is the ground voltage, the driving voltage is 20 V, the distance between the anode 54 and the substrate 1 is 5 mm, the dielectric constant ε1 of the insulating layer 8 and the dielectric constant ε2 between the anode 54 and the substrate 1 When the ratio ε1 / ε2 is 5, by setting the thickness of the insulating layer 8 to about 0.05 mm or less, the anode applied voltage is 10 kV or less, and the rise of the surface potential can be suppressed to the drive voltage or less. is there. As can be seen from this, if a conductive layer is formed on the back surface of the substrate having a relative dielectric constant of about 5 and a ground voltage is applied to the conductive layer, the thickness of the substrate is reduced to about 0.05 mm or less. And it becomes very difficult to obtain sufficient strength in response to the increase in area.
[0121]
【Example】
Hereinafter, the present invention will be described in detail with reference to specific examples, but the present invention is not limited to these examples, and the replacement and design of each element within a range where the object of the present invention is achieved. Includes any changes made.
[0122]
[Example 1]
A method for manufacturing an electron source using a surface conduction electron-emitting device will be described with reference to FIGS.
[0123]
1) The glass substrate 6 is washed. The substrate uses blue plate glass.
[0124]
2) forming the conductive layer 7; The conductive layer 7 is composed of 0.01 μm of Cr / 0.3 μm of Cu / 0.01 μm of Cr, and is formed by a vacuum evaporation method.
[0125]
3) forming the insulating layer 8; The insulating layer 8 is formed by forming a PSG film having a phosphorus concentration of 6% by weight with a thickness of 2 μm. A CVD method is used for the formation. In order to obtain a terminal for applying a voltage to the conductive layer 7, hydrofluoric acid is dropped on the insulating layer 8 to form a portion where the conductive layer 7 is exposed (not shown) at the end of the substrate. The area of this exposed part is about one square centimeter.
[0126]
4) Form device electrodes 2 and 3. A thick film printing method is used as a film forming method. The thick film paste material used here is MOD paste (DU-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 is 0.3 μm. The distance between the device electrodes is 50 μm.
[0127]
5) Next, the Y-direction wiring 73 is formed. A thick screen printing method is used. The paste material is Noritake Co., Ltd. product (NP-4028A), and the metal component is silver. Firing is the same as in 2). The Y-direction wiring is connected to one side of the element electrode 3.
[0128]
6) Next, an interlayer insulating layer (not shown) is formed. A thick screen printing method is used. The paste material used is a mixture of PbO as a main component and a glass binder. Firing is the same as in 2). The X-direction wiring 72 and the element electrode 2 are connected.
[0129]
7) Next, the X direction wiring 72 is formed in the same procedure as the Y direction wiring 73. Part of the X-direction wiring 72 is connected to the element electrode 2.
[0130]
8) Next, the conductive thin film 4 is formed. The organic palladium-containing solution is applied to a width of 200 μm by using a bubble jet type inkjet ejecting apparatus. A heat treatment is performed at 300 ° C. for 10 minutes to obtain a fine particle film composed of fine palladium oxide particles.
[0131]
The composite substrate 1 having the conductive layer 7 and the insulating layer 8 formed on the glass substrate 6 by the above steps, the X-directional wiring 72, the interlayer insulating layer (not shown), the Y-directional wiring 73, the device electrodes 2 and 3, the electron emitting portion The forming thin film 4 and the like are formed.
[0132]
Using the electron source substrate thus manufactured, an envelope 88 is formed by the face plate 86, the support frame 82, and the rear plate 81 as described above, and sealing is performed to produce a display panel.
[0133]
The inside of the envelope 88 is evacuated to a pressure of 1.3 × 10 ^-4 After the pressure is reduced to Pa or less, the above-described forming process is performed by setting the Y-direction wiring 73 to the ground potential and applying a triangular wave pulse to each of the X-direction wirings 72. As shown in FIG. 5B, the waveform of the triangular wave pulse has a gradually increasing peak value, and has a pulse width T1 = 1 msec. And a pulse interval of 10 msec. And
[0134]
Subsequently, an activation step is performed. Acetone is introduced into the envelope 88, and the pressure is set to 1.3 × 10 ^-1 Pa, and a rectangular wave pulse having a peak value of 16 V is applied to each X-direction wiring in the same manner as described above.
[0135]
Subsequently, air was exhausted while heating the envelope 88, and the pressure was increased to 1.3 × 10 3. ^-5 After the pressure is reduced to Pa or less, the exhaust pipe is heated and welded by a burner, sealing is performed, and a getter (not shown) is heated by high frequency to perform a getter process.
[0136]
In this display panel, the distance d2 between the anode 54 and the substrate 1 is 5 mm, the thickness d1 of the insulating layer is 2 μm, and the ratio ε1 / ε2 of the dielectric constant ε1 of the insulating layer and the dielectric constant ε2 between the anode and the substrate is about 5 μm. And
V2 = V1 / (1+ (d2 × ε1) / (d1 × ε2))
Is given by V2 = V1 / 12501. The voltage V1 is a voltage applied to the anode 54. Further, an image forming apparatus having a drive circuit for performing a television system based on an NTSC television signal as shown in FIG. 11 is manufactured.
[0137]
In order to confirm the presence / absence of discharge in the image forming apparatus manufactured by the above method over a long period of time, an experiment was conducted in which a current suddenly flowing through the anode electrode 54 when a discharge occurred was measured. The measurement conditions are described below.
[0138]
1) The voltage V1 applied to the anode 54 was increased at 10 kV and 2 kV per second. The driving voltage of the electron-emitting device 74 was set to 16V. That is, rectangular wave pulses having peak values of +8 V and -8 V were applied to wirings in the X and Y directions corresponding to the elements to be made to emit electrons. At this time, the voltage V2 was about 0.8 V, which was smaller than the potential 8 V on the positive electrode side.
[0139]
2) A ground voltage shared with the ground of the high-voltage power supply was applied to the conductive layer 7. That is, a voltage that does not fluctuate with time was applied to the conductive layer 7.
[0140]
3) The driving conditions were such that the driving voltage and the pulse width were the same for each element. That is, the condition is such that the current value flowing through the anode 54 has little variation over time.
[0141]
4) When a value twice the current value constantly flowing through the anode 54 is set as a trigger level, and a current suddenly exceeds the above trigger level due to discharge and subsequently attenuates to a current value below the trigger level. Then, it was assumed that discharge occurred. It should be noted that, at the time of discharge, light emission of the phosphor may be observed at the discharge location, but the above-described measurement method was sufficient. According to the above-described measuring method, the number of times of discharge can be measured for a long time.
[0142]
When the above measurement was performed for 200 hours, no discharge was observed. From this, it is understood that the electron source and the image forming apparatus of the present invention are extremely effective in suppressing discharge.
[0143]
Next, when various drive signals were input in order to evaluate the image, the electron-emitting device electron source substrate, display panel, and image forming apparatus manufactured by the manufacturing method of the above-described embodiment showed that the pixel was not disordered. No stable images were obtained.
[0144]
[Comparative Example 1]
In Example 1, steps 2) and 3) were not performed, that is, an element was formed directly on the glass substrate 6, and a discharge measurement experiment similar to that performed in Example 1 was performed. Note that a glass substrate having a relative dielectric constant of about 5 and a thickness of 2 mm was adopted, and the glass substrate was arranged such that the back surface of the element forming surface of the glass substrate was at the ground potential. When the same driving voltage and anode applied voltage as in Example 1 were applied for 200 hours, eight discharges were measured. Subsequently, when various drive signals were input in order to evaluate an image, the electron source, the display panel, and the image forming apparatus manufactured by the manufacturing method of Comparative Example 1 showed an unclear display which is considered to be caused by discharge. Part was confirmed.
[0145]
[Example 2]
In Example 1, the following steps 2) 'and 3)' were performed instead of steps 2) and 3). Other steps are the same as in the first embodiment.
[0146]
2) 'The conductive layer 7 is formed in the shape shown in FIG. The conductive layer 7 is composed of 0.01 μm of Cr / 0.3 μm of Cu / 0.01 μm of Cr, and uses a vacuum deposition method for film formation. Note that in order to obtain the shape shown in FIG. 2, a resist is applied before film formation, patterning is performed using a photolithography technique to obtain a desired shape, and lift-off is performed after film formation. It should be noted that C and C 'in FIG. 2 are later aligned so as to coincide with B and B' in FIG. 1 when viewed from a direction perpendicular to the substrate.
[0147]
3) ′ Form the insulating layer 8. The insulating layer 8 is formed by forming a PSG film having a phosphorus concentration of 6% by weight at 1 μm. A CVD method was used as a forming method.
[0148]
Using the electron source substrate thus manufactured, an envelope 88 is formed by the face plate 86, the support frame 82, and the rear plate 81 as described above, and the display panel is further sealed by performing sealing as shown in FIG. An image forming apparatus having a drive circuit for performing television display based on such NTSC television signals was manufactured. In this display panel, the distance d2 between the anode and the substrate is 5 mm, the thickness d1 of the insulating layer is 1 μm, and the ratio ε1 / ε2 between the dielectric constant ε1 of the insulating layer and the dielectric constant ε2 between the anode and the substrate is about 5. ,
V2 = V1 / (1+ (d2 × ε1) / (d1 × ε2))
Is V2 = V1 / 25001. The voltage V1 is a voltage applied to the anode.
[0149]
First, in the same manner as in Example 1, in order to confirm the presence / absence of discharge for a long period of time, an experiment was conducted for 200 hours in which the current suddenly flowing to the anode electrode when a discharge occurred was measured. The experimental conditions were the same as in Example 1, and as a result, no discharge was observed.
[0150]
Next, when various driving signals were input to evaluate the image, the electron source substrate, the display panel, and the image forming apparatus manufactured by the manufacturing method of the present embodiment described above were stable without pixel disorder. An image was obtained.
[0151]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an electron emission element electron source substrate, a display panel, and an image forming apparatus in which discharge is suppressed.
[Brief description of the drawings]
FIG. 1 is a schematic plan view and a cross-sectional view showing a configuration of an electron source using a surface conduction electron-emitting device according to an embodiment and an example of the present invention.
FIG. 2 is a schematic plan view showing a conductive layer formed on a substrate according to a second embodiment of the present invention.
FIG. 3 is a schematic view showing a first half of an example of a method for manufacturing a surface conduction electron-emitting device according to an embodiment and an example of the present invention.
FIG. 4 is a schematic view showing a latter half of an example of a method for manufacturing a surface conduction electron-emitting device according to the embodiment and the example of the present invention.
FIG. 5 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 according to the embodiment and the example of the present invention.
FIG. 6 is a schematic diagram illustrating an example of a vacuum processing apparatus having a measurement evaluation function.
FIG. 7 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 according to the embodiment and the example of the present invention.
FIG. 8 is a schematic diagram showing an example of an electron source arranged in a simple matrix according to the embodiment and the example of the present invention.
FIG. 9 is a schematic diagram illustrating an example of a display panel of the image forming apparatus according to the embodiments and examples of the present invention.
FIG. 10 is a schematic diagram illustrating an example of a fluorescent film.
FIG. 11 is a block diagram illustrating an example of a drive circuit for causing an image forming apparatus to perform display in accordance with an NTSC television signal.
FIG. 12 is a schematic diagram illustrating an example of an electron source having a ladder arrangement according to an embodiment of the present invention.
FIG. 13 is a schematic diagram illustrating an example of a display panel of the image forming apparatus according to the embodiment of the present invention.
FIG. 14 is a schematic view of a vacuum evacuation apparatus for performing a forming and activating process of an image display device according to embodiments and examples of the present invention.
FIG. 15 is a schematic diagram showing a connection method for forming and activating processes of the image forming apparatus according to the embodiment and the example of the present invention.
FIG. 16 is a schematic view showing an example of a conventional surface conduction electron-emitting device.
[Explanation of symbols]
1 Composite board
2,3 element electrode
4 Conductive thin film
5 Electron emission section
6 substrate
7 Conductive layer
8 Insulating layer
9 Interlayer insulation layer
50 Ammeter for measuring element current If flowing through conductive thin film 4 between element electrodes 2 and 3
51 Power supply for applying device voltage Vf to electron-emitting device
52 Ammeter for measuring an emission current Ie emitted from the electron emission section 5 of the element
53 High-voltage power supply for applying voltage to anode 54
54 Anode electrode for capturing emission current Ie emitted from the electron emission portion of the device
55 vacuum equipment
56 Exhaust pump
71 Electron source board
72 X direction wiring
73 Y direction wiring
74 surface conduction electron-emitting device
75 connections
81 Rear plate
82 Support Frame
83 glass substrate
84 fluorescent film
85 metal back
86 face plate
87 High voltage terminal
88 envelope
91 black conductive material
92 phosphor
101 Display panel
102 scanning circuit
103 control circuit
104 shift register
105 line memory
106 Synchronous signal separation circuit
107 Modulation signal generator
Vx and Va DC voltage source
110 electron source substrate
111 electron-emitting device
112 Dx1 to Dx10 are common wirings for wiring the electron-emitting devices.
120 grid electrode
Vacancy due to 121 electrons passing
122 Dox1, Dox2,... Doxm external terminal
123 G1, G2 connected to grid electrode 120
131 Image display device
132 exhaust pipe
133 vacuum chamber
134 Gate valve
135 Exhaust system
136 Pressure gauge
137 quadrupole mass spectrometer
138 Gas introduction line
139 Introduction amount control means
140 Source of Introduced Substance
141 common electrode
142 Power
143 Resistance for current measurement
144 oscilloscope

Claims (2)

A substrate having a plurality of electron-emitting elements are arranged, in the electron source having an anode electrode disposed on sides of the plurality of electron-emitting devices, between the substrate and the plurality of electron-emitting devices, the ground a conductive layer which is defined potential, is arranged an insulating layer which insulates between the conductive layer and the plurality of electron-emitting devices, the insulating layer, the potential of the surface of the insulating layer is the electron emission An electron source having a thickness that is equal to or less than a maximum value of a potential applied to an element . An image forming apparatus comprising the electron source according to claim 1 and an image forming member.

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