JP6889629B2 - Manufacturing method of electron emitting element and electron emitting element - Google Patents

Description

The present invention relates to an electron emitting element and a method for manufacturing an electron emitting element.

The applicant has developed an electron emitting element having a novel structure that can operate in the atmosphere (see, for example, Patent Document 1).

Patent Document 2 describes electron emission, which can suppress deterioration of the electron acceleration layer (intermediate layer), enable efficient and stable electron emission not only in vacuum but also in atmospheric pressure, and further enhance mechanical strength. The element is disclosed. Specifically, this electron emitting element includes an electrode substrate, an insulating layer having an opening formed on the electrode substrate, an electron accelerating layer (intermediate layer) formed on the insulating layer, and an electron accelerating layer (an electron accelerating layer). It is provided with a thin film electrode formed on the intermediate layer). The electron accelerating layer (intermediate layer) contains a binder resin in which insulating fine particles and conductive fine particles are dispersed, and an electrode in which an insulating layer is formed by a spin coating method or a spray method on a mixed solution of the binder resin. It is formed by applying it on a substrate.

In Patent Document 3, in order to enable an increase in the size of the electron emitting element, it is necessary to suppress the formation of a potential gradient in the thin film electrode depending on how a voltage is applied, that is, there is almost no potential distribution in the thin film electrode surface. In order to enable uniform voltage application, the structure includes an electrode substrate, a fine particle layer, a thin film electrode, and an electrically insulating layer, and has a plurality of openings. The fine particle layer is an insulating fine particle and conductive. It is composed of a first fine particle layer composed of fine particles and a second fine particle layer composed of insulating fine particles.

JP-A-2009-146891 (Patent No. 4303308) Japanese Unexamined Patent Publication No. 2010-198850 Japanese Unexamined Patent Publication No. 2013-37784

However, the electron emitting element disclosed in Patent Document 2 employs a spin coating method or a spray method to form an electron accelerating layer (intermediate layer) in order to form an electron accelerating layer (intermediate layer) on the order of particles. Therefore, even if an attempt is made to apply a mixed solution of a binder resin in which insulating fine particles and conductive fine particles are dispersed on the electrode substrate and only in the opening, the coating on the insulating layer or the element There was room for improvement in terms of effective utilization of the mixed liquid (coating liquid), that is, the insulating fine particles and the conductive fine particles.

Further, the electron emitting device disclosed in Patent Document 3 has the same problems as in Patent Document 2 described above, and in order to increase the size, it is possible to apply an almost uniform voltage in the thin film electrode surface. In addition, since the electrical insulating layer is made of acrylic resin and has a complicated structure, the initial performance varies.

Therefore, it is an object of the present invention to effectively utilize the mixed liquid for forming the semi-conductive portion which is the intermediate layer, and to suppress the variation in the initial performance when the size is increased.

In order to solve the above problems, according to the present invention, an insulating portion provided between the first electrode, the second electrode, the first electrode and the second electrode, and a predetermined opening is provided. It is provided with a semi-conductive portion arranged in the opening between the first electrode and the second electrode, and the voltage is applied between the first electrode and the second electrode. An electron emitting element that emits electrons from a second electrode, which has the insulating portion in the electron emitting region of the first electrode, and the semi-conductive portion contains conductive fine particles and insulating fine particles having photocatalytic performance. It is characterized by being

Further, the insulating portion may be made of an oxide of the first electrode.

Further, the insulating portion may exist not only above the surface of the first electrode but also inside the first electrode.

Further, the electron emitting region of the first electrode may have a sea-island structure composed of the semi-conductive portion and the insulating portion.

Further, the sea-island structure may have a parallel shape, a staggered shape, or an indefinite shape.

Further, in the electron emitting region of the first electrode, the area ratio of the semi-conductive portion may be 30 to 80% with respect to the semi-conductive portion and the insulating portion.

Further, the first electrode may be made of a metal plate on which an oxide film can be formed by anodic oxidation or a substrate on which a metal film is formed.

The opening may penetrate between the first electrode and the second electrode. Further, an insulating portion forming step of forming an insulating portion having a predetermined opening on the first electrode, and a semiconductive portion forming step of forming a semiconductive portion which is an intermediate layer in the opening on the first electrode. The semi-conductive portion is composed of a second electrode forming step of forming a second electrode for emitting electrons on the semi-conductive portion and the insulating portion, and in the semi-conductive portion forming step, the semi-conductive portion is formed by electrophoresis deposition. In the insulating portion forming step including the step, a method for manufacturing an electron emitting element is provided, which comprises forming the insulating portion having the predetermined opening at least in an electron emitting region.

Further, the insulating portion forming step is characterized in that the insulating portion is formed by anodic oxidation of the first electrode.

Further, in forming the insulating portion in the electron emitting region of the first electrode in the insulating portion forming step, the insulating portion is formed so that the insulating portion or the semi-conductive portion has a sea-island structure. It is a feature.

Further, according to the present invention, the semi-conductive portion contains conductive fine particles and insulating fine particles, and the conductive fine particles are composed of supported particles supported on the insulating fine particles.

Further, according to the present invention, the semi-conductive portion forming step includes an insulating fine particle layer forming step of forming an insulating fine particle layer on the first electrode having the insulating portion having a predetermined opening. It is characterized by comprising a step of supporting conductive fine particles in which the conductive fine particles are supported on the insulating fine particles constituting the insulating fine particle layer.

Further, according to the present invention, in the electrophoresis deposition, the first insulating layer having a predetermined opening is formed in a suspension solution in which the insulating fine particles or the supporting particles are dispersed in a dispersion medium. The electrode is used as an anode or a cathode, and the electrode is immersed together with the opposite electrode or the anode, and then a controlled voltage and / or current is applied to determine the insulating fine particle layer or the supporting particle layer constituting the semi-conductive portion. It is characterized in that the insulating portion having the opening is formed on the first electrode.

Further, according to the present invention, the first electrode is characterized by being composed of a metal plate on which an oxide film can be formed by anodic oxidation or a substrate on which a metal film is formed.

Further, according to the present invention, the insulating fine particles have an average primary particle diameter of 1 nm to 1000 nm.

Further, according to the present invention, the insulating fine particles are characterized as being insulating fine particles having photocatalytic performance.

Further, according to the present invention, the conductive fine particles are characterized in that they are 3 nm to 80 nm.

According to the present invention, by using the electrophoretic deposition method when forming the semi-conductive portion, the insulating fine particles and the conductive fine particles can be effectively used efficiently, and variations in the initial performance can be suppressed. Can be done.

It is the schematic sectional drawing of the electron emission element of the 1st Embodiment of this invention. It is a top view of the electron emitting element of FIG. It is the schematic cross-sectional view which shows the manufacturing process of the electron emitting element of FIG. It is the schematic cross-sectional view which shows the manufacturing process of the electron emitting element of FIG. It is the schematic cross-sectional view which shows the manufacturing process of the electron emitting element of FIG. It is the schematic cross-sectional view which shows the manufacturing process of the electron emitting element of FIG. It is explanatory drawing of the method of forming the insulating fine particle layer 5d which constitutes the semi-conductive part 5 in the electron emitting element 1 shown in FIG. It is explanatory drawing of the method of forming the semi-conductive part 5 in the electron emitting element 1 shown in FIG. It is the schematic cross-sectional view of the electron emitting element 50 of the comparative example 2, and the figure which looked at the electron emitting element 50 from the cut plane line AA. It is explanatory drawing which shows the measurement system of the electron emission experiment performed on the electron emission element. It is a figure which shows the example of the arrangement of the sea-island structure formed in the electron emission region 7 of an electron emission element 1.

Hereinafter, the electron emitting element according to the embodiment of the present invention will be described with reference to the drawings.

1 (a) and 1 (b) are schematic cross-sectional views of an electron emitting device according to the first embodiment of the present invention. FIG. 2 is a plan view of the electron emitting element shown in FIGS. 1 (a) and 1 (b).

The electron emitting element 1 includes a first electrode 2 which is also called an electrode substrate, an insulating portion 3 having a predetermined opening 4, and an intermediate portion which is also called an electron accelerating layer formed in the opening 4 of the insulating portion 3. A semi-conductive portion 5 and a second electrode 6 which are layers are provided.

In the electron emitting device, the negative electrode of the power supply is connected to the first electrode 2, and the positive electrode of the power supply is connected to the second electrode 6. Therefore, the electrons flowing through the electron emitting element 1 are accelerated from the first electrode 2 toward the second electrode 6 in the semi-conductive portion 5, and some electrons are emitted from the second electrode 6 as hot electrons. Such an electron emitting device can be suitably used as a charging device for charging the surface of the photoconductor drum, for example, in an electrophotographic image forming device. In addition to this, it can be applied to an electron beam curing device, an image display device combined with a light emitting body, an ion wind generator using ion wind generated by emitted electrons, and the like.

The first electrode 2 may be made of a support having electrical conductivity such as a metal plate, and may have sufficient electrical conductivity, and may be a metal capable of forming an oxide film by anodic oxidation. As a specific example, it is formed from a conductive material such as aluminum, copper, and stainless steel. The first electrode 2 may be a glass substrate or a plastic substrate having a metal film formed on its surface in order to have its own rigidity. For example, an FTO transparent conductive substrate or a transparent conductive film (ITO film) glass substrate may be used. At this time, in the case of an insulating substrate such as a glass substrate, a conductive layer may be formed between the metal film and the metal film, and the metal film and the conductive layer may be used as electrodes. The thickness of the electrode film (the portion remaining after anodic oxidation) that functions as an electrode is preferably, for example, 10 μm or more.

The insulating portion 3 may be electrically insulating in order to prevent the electron emission from being hindered by the direct movement of electrons from the first electrode 2 to the second electrode 6. The thickness of the insulating portion 3 may be about 1 μm to 5 μm. If it is thinner than 1 μm, the risk of short circuit increases, and if it is larger than 5 μm, the electron emission performance is affected.

The insulating portion 3 is made of an oxide of the first electrode 2. More specifically, aluminum may be used for the first electrode 2, and aluminum oxide (Al ₂ O ₃ ), which is a metal oxide film, may be formed on the first electrode 2 by anodization treatment or the like. When anodic oxidation is used, the oxide film formed as shown in FIG. 1B may be formed up to the inside of the electrode, that is, the structure may be such that oxides are present above and below the surface of the first electrode.

The insulating portion 3 or the semi-conductive portion 5 existing in the electron emitting region 7 may have a sea-island structure. The sea-island structure can be arranged in a staggered, parallel, or indefinite shape. FIG. 11 shows an example of the arrangement of the sea island structure. The island-shaped portion is the insulating portion 3 or the semi-conductive portion 5. Specific arrangements are (a) round staggered, (b) round staggered, (c) square staggered, (d) square parallel, (e) long angle parallel, (f) rhombus, and (g) hexagonal shell. ..

The insulating portion 3 is provided with an opening 4 for emitting the electrons generated by the first electrode 2. For example, when aluminum is used for the first electrode 2 and the insulating portion 3 is manufactured by anodic oxidation treatment or the like, the opening 4 is masked at the time of anodic oxidation treatment or caustic soda or the like after the entire surface is anodicated. It can be manufactured by forming it by performing an etching process using.

The semi-conductive portion 5 is formed on the first electrode 2 and in the opening 4. The thickness of the semi-conductive portion 5 may be about 0.3 μm to 5 μm.

The semi-conductive portion 5 contains insulating fine particles 5a and conductive fine particles 5b. In particular, it is preferable that the insulating fine particles 5a having photocatalytic performance contain a plurality of supported particles in which the conductive fine particles 5b are supported. Further, it may contain an insulating resin which is a binder. The binder resin is not particularly limited as long as it is a material having an insulating property, and most resins can be used. For example, a silicone resin can be used, and the curing type thereof is not particularly limited. The insulating fine particles 5a and the conductive fine particles 5b are mostly insulating fine particles 5a in quantity, and the secondary particle size of the insulating fine particles 5a needs to be larger than the particle size of the conductive fine particles 5b in terms of size.

The average secondary particle size of the insulating fine particles 5a is preferably 0.05 μm to 5.0 μm. When considering the deposition of insulating fine particles by the electrophoresis deposition method, if it is smaller than 0.05 μm, it becomes difficult to disperse it, and if it is larger than 5.0 μm, the film thickness of the semi-conductive part becomes too thick, so that the conduction path Cannot be formed and does not function as an electron emitting device. The average primary particle size is preferably 1 nm to 1000 nm, more preferably 5 nm to 400 nm, and further preferably 20 nm to 200 nm.

Materials of the insulating fine particles 5a include silicon oxide, aluminum oxide, titanium oxide, tungsten oxide, barium titanate, strontium titanate, sodium tantalate (NaTaO ₃ ), tin oxide, zinc oxide, zirconium oxide, manganese oxide and the like. Tantal (niobium) oxynitrides containing transition metals such as metal oxides, LaTIO ₂ N, CaTaO ₂ N, SrTaO ₂ N, BaTaO ₂ N, LaTaON ₂ , CaNbO ₂ N, SrNbO ₂ N, BaNbO ₂ N, LaNbON _2. , Oxide nitrides such as tantalum oxynitrides, nitrides such as aluminum nitride, gallium nitride and tantalum nitrides, and sulfides such as cadmium sulfide can be used. In particular, the material of the insulating fine particles 5a having photocatalytic performance may be a semiconductor material, and metal oxides, oxynitrides, nitrides and sulfides having photocatalytic functions are preferable, for example, titanium oxide (TiO ₂ ). , barium titanate (BaTiO _3), strontium titanate (SrTiO _3), tungsten oxide _(WO 3), sodium tantalate (NaTaO _3), zinc oxide, or the like can be used cadmium sulfide. Alternatively, it is possible to use these in combination. In particular, in order to apply the production method using the photoprecipitation method described later, it is essential that the metal oxide, oxynitride, nitride, and sulfide function as a photocatalyst. Of these, titanium oxide (TiO ₂ ) is preferably used. The crystal structure of titanium oxide may be any of anatase type, rutile type and brookite type. The titanium oxide preferably has an average secondary particle size of 0.1 μm to 5.0 μm and an average primary particle size of 1 nm to 1000 nm.

As the conductive fine particles 5b, any conductor can be used as long as it can be supported by the insulating fine particles 5a. However, for the purpose of avoiding oxidative deterioration when operated at atmospheric pressure, it is necessary to use a conductor having high antioxidant power, and a metal is preferable, and a noble metal is more preferable. Examples include materials such as gold, silver, copper, rhodium, platinum, palladium, nickel, ruthenium and cobalt. Further, as the material of the conductive fine particles 5b, fine powders other than metals such as fullerenes and carbon nanotubes can also be used. The conductive fine particles 5b have a smaller particle size than the insulating fine particles 5a, and the range thereof is 3 nm to 80 nm, preferably 5 nm to 10 nm.

The second electrode 6 is not limited to this, but as a whole, a metal material such as gold, a semiconductor, an ITO (indium tin oxide), carbon, or the like is used to prevent excessive destruction. It can be composed of a plurality of thin films of conductive materials having high conductivity. The total layer thickness of the second electrode 6 may be determined in consideration of its in-plane resistance and the amount of electron emission. For example, it may be 0.01 μm to 0.1 μm. Each layer of the second electrode 6 may be sequentially formed into a film and stacked, or the layer may be ion-implanted after the layer is formed to change the quality of the second electrode 6.

3 to 6 are schematic plan views showing an example of a manufacturing process of the electron emitting element 1 of FIGS. 1A and 1B.

Step (1): Insulating portion 3 forming step As shown in FIG. 3, the insulating portion 3 is formed on the first electrode 2. FIG. 3 shows, as an example, the case of a round staggered pattern (FIG. 11 (a)) as an arrangement of the sea-island structure of the insulating portion 3 in the electron emission region 7. For example, when an aluminum plate is used for the first electrode 2, the insulating portion 3 is patterned and formed so as to have an opening 4 for a region through which a current flows through the semiconductive portion 5 by a screen printing method, and then the anode is formed. Alumite can be formed in the three insulating portions by the oxidation treatment. Actually, when the insulating portion 3 is anodized, the end portion of the opening 4 does not have a clean wall shape as shown in FIGS. 1 (a) and 1 (b), and has a dull shape like a log curve. It becomes.

Step (2): Insulating Fine Particle Layer 5d Forming Step As shown in FIG. 4, an insulating fine particle layer composed of insulating fine particles 5a constituting the semiconductive portion 5 on the first electrode 2 and in the opening 4. Form 5d. As a method of forming, it can be formed by an electrophoretic deposition method described later.

Step (3): Step of supporting conductive fine particles 5b As shown in FIG. 5, of the first electrode 2 forming the insulating fine particle layer 5d composed of the insulating portion 3 and the insulating fine particles 5a, the insulating fine particles 5a are conductive. The fine particles 5b are supported to form the supporting particles 5c. As for the method of supporting the conductive fine particles 5b, electroless plating and the impregnation method, the citric acid reduction method, the air reduction method and the photodeposition method described later are used as a method of reducing the aqueous solution containing the metal ion to be supported to support the metal. is there.

Step (4): Second Electrode 6 Forming Step As shown in FIG. 6, the second electrode 6 is formed on the semi-conductive portion 5 by using a vacuum deposition method or a sputtering method using, for example, a metal. When the second electrode 6 has two or more layers, various metals are sequentially formed according to each pattern by a vacuum vapor deposition method, a sputtering method, or the like.

In the above-mentioned steps, it is also possible to replace the above-mentioned steps (2) and (3) with the following steps (2a) and (3a).

Step (2a): Step of producing supported particles 5c The conductive fine particles 5b are supported on the insulating fine particles 5a to prepare the supported particles 5c. Examples of the supporting method include an impregnation method, an ion exchange method, a precipitation precipitation method, a coprecipitation method, and a graphing (adhesion) method. For example, the impregnation method is a method in which a supported medium powder is immersed in a colloidal solution in which metal nanoparticles are dispersed, and then the colloidal solvent is evaporated to dryness to reduce hydrogen in the obtained dry matter. In the ion exchange method, a metal cation or complex anion is ion-exchanged with hydrogen ions or hydroxide ions on the surface of the supporting medium powder, washed with water, filtered, and dried, calcined, or reduced. How to do it. In the precipitation-precipitation method, by adjusting the pH of the aqueous metal salt solution, a precipitate of metal hydroxide is precipitated and supported only on the surface of the supporting medium powder, washed with water, filtered, and dried, calcined, or fired. It is a method of reduction. In the co-precipitation method, each metal salt used as a raw material of a supporting medium composite carrying a catalyst metal, a metal oxide, or the like is used as a mixed aqueous solution, and the insoluble hydroxide or carbonate obtained by adding an alkali is washed with water. This is a method of drying, firing, and reducing a product obtained by filtration. The graphing method is, for example, a method in which vapor of an organometallic complex is adsorbed on the surface of a supported medium powder, fired in the atmosphere, and then hydrogen-reduced.

Step (3a): Step of forming a supported particle layer 5e A supported particle layer 5e composed of supported particles 5c constituting the semi-conductive portion 5 is formed on the first electrode 2 and in the opening 4. As a method of forming, it can be formed by an electrophoretic deposition method described later.

In addition to the above steps, it is also possible to add an annealing step of the insulating fine particle layer 5d between the above steps (2) and (3) in order to improve the adhesion of the insulating fine particle layer 5d and prevent peeling. is there.

Step (2'): Insulating fine particle layer 5d annealing step The insulating fine particle layer 5d formed in step (2) is annealed. The annealing treatment can be carried out in air, in a non-oxidizing atmosphere, in vacuum, for example, at a temperature of 100 ° C. to 500 ° C. for about 1 hour to 4 hours.

Further, in order to produce a structure in which the semi-conductive portion 5 contains a binder, the following steps can be added between the above steps (3) and (4).

Step (3'): Binder-containing step An insulating resin as a binder is supplied onto the supporting particles 5c and / or the insulating portion 3 to form the semi-conductive portion 5 containing the supporting particles 5c. In this binder-containing step, the distance between the first electrode 2 and the second electrode 6 can be adjusted by adjusting the thickness of the semi-conductive portion 5 according to the supply amount and method of the insulating resin. For the formation of the semi-conductive portion 5 containing the binder, for example, a method such as applying a silicone resin or the like by using a spin coating method or a spray coating method and curing the semi-conductive portion 5 can be used.

7 and 8 show a part of the method of forming the semi-conductive portion 5 in the electron emitting element 1 shown in FIGS. 1 (a) and 1 (b), and FIGS. 7 (a) and 7 (b) show electricity. Regarding the electrophoretic deposition method, FIG. 8 is a simplified explanatory view of the photodeposition method.

Electrophoretic deposition method:
In the electrophoresis deposition method, in order to form a substrate on which fine particles are to be deposited, the substrate is immersed in a solution in which the fine particles are suspended in a dispersion medium with the substrate as an anode or a cathode together with a cathode or an anode which is a counter electrode, and then the substrate is immersed. This is a method in which a controlled current and / or voltage is applied between the substrate and the counter electrode, and suspended fine particles are electrophoretically deposited on the substrate. Here, the suspended fine particles need to be positively or negatively charged. The dispersion medium is not particularly limited as long as it does not inhibit the deposition of fine particles due to the electrolysis of the dispersion medium itself occurring during the deposition of fine particles. Examples of the dispersion medium include alcohols such as ethanol and methanol, ketones such as acetone and methyl ethyl ketone, aromatic hydrocarbons such as toluene and xylene, sulfoxides such as dimethyl sulfoxide (DMSO), and carbonates such as propylene carbonate and dimethyl carbonate. , Ethers such as dimethyl ether and ethyl methyl ether, esters such as ethyl acetate and methyl acetate, furans such as tetrahydrofuran and the like. It is also possible to use a dispersion aid such as a surfactant in addition to the dispersion medium. The concentration of the fine particles for dispersion is preferably 0.1 to 10 wt%. Depending on the powder physical properties of the fine particles to be dispersed, if it is larger than 10 wt%, the dispersion may not be sufficient, and if it is smaller than 0.1 wt%, the amount of deposition may be small.

It is also possible to use an antistatic agent as an additive to positively or negatively charge the surface of the suspended fine particles. For example, iodine can be used for positive charging. Further, in order to be negatively charged, a basic compound as a substance that receives H + (proton receptor) can be used. Examples of the basic compound include carboxylic acid derivatives, aliphatic amines, heterocyclic amines, aromatic amines and the like. Specifically, examples of the carboxylic acid derivative include tetramethylguanidine (TMG), guanidine, diphenylguanidine and the like, and examples of the aliphatic amine include ethylamine, triethylamine (TEA), tributylamine and the like. Examples of the heterocyclic amine include pyridine (Py) and the like, and examples of the aromatic amine include aniline and the like.

7 (a) and 7 (b) are simple explanatory views regarding the formation of the insulating fine particle layer 5d by the electrophoretic deposition method when _{titanium oxide (TiO 2) is used as the insulating fine particles 5a, for example.}

_{FIG. 7A shows that a suspension solution 200 containing iodine and acetone in which TiO 2} which is the insulating fine particles 5a is dispersed is present in the reaction vessel 100.

In FIG. 7 (b), the suspension solution 200 shown in FIG. 7 (a) was used, and TiO ₂ , which is the insulating fine particles 5a, was attached to the first electrode 2 by an electrophoresis device connected to the power supply 300. Indicates the state. The first electrode 2 was used as an anode electrode, and aluminum or the like was used as the counter electrode 400 to serve as a cathode electrode, which was connected to the power supply 300. Generally, SUS, Pt (plate, wire) or the like is often used as the cathode electrode. The power supply 300 can control the current and / or voltage such as constant current, constant current pulse, constant voltage, constant voltage pulse, constant power, etc., and the controlled current and / or voltage is applied to the anode electrode and the cathode. It can be supplied between the electrodes.

The voltage applied by the power supply 300 may be about 2V to 10V. When a constant current / constant voltage pulse is supplied from the power supply 300, the frequency may be 1 Hz to 1000 Hz.

Further, the time for processing the first electrode 2 by the electrophoresis device may be about 10 seconds to 5 minutes. The higher the applied voltage and the longer the processing time, the thicker the semi-conductive portion 5 becomes. Therefore, these voltage values or current values and the processing time may be determined in consideration of the thickness of the insulating portion 3. ..

Photocatalytic method The photocatalytic method here is a photocatalyst in a state where a solution (reaction solution) containing metal ions related to the metal to be supported is brought into contact with an insulating material having photocatalytic performance. A method in which metal ions and the like are reduced by electrons excited by an insulating material (including a semiconductor material) having photocatalytic performance by shining light that exhibits performance, and the metal is supported on the insulating material having photocatalytic performance. Is. Here, the solvent used in the solution containing the metal ions and the like related to the metal to be supported is not particularly limited as long as it is a solvent in which the metal ions and the like related to the metal to be supported are dissolved. However, since the metal ion is reduced to the metal, the solvent may be used as long as the oxidation reaction occurring on the insulating material having photocatalytic performance paired with the metal ion does not interfere with the reduction of the metal ion. Suitable solvents include aqueous water and methanol solutions. When an alcohol solvent is included, the electrons in the valence band are excited and moved to the conduction band by irradiating light with an energy equal to or higher than the band gap of the photocatalytic material, and react with the holes of the electrons generated in the valence band, that is, holes. To oxidize the alcohol. By consuming the holes in the reaction, the recombination of excited electrons and holes can be suppressed and the reduction reaction can be promoted. In the photoprecipitation method, the reaction proceeds more by stirring, so Ag may be supported while stirring. Further, as the light source used when shining light, a light source having a wavelength capable of exhibiting photocatalytic performance is used. For example, in _{the case of titanium oxide (TiO 2} ), an ultraviolet lamp can be used.

FIG. 8 shows an example of a photodeposition method in which conductive fine particles 5b are supported on insulating fine particles 5a. _{In this example, when silver is supported as the conductive fine particles 5b on titanium oxide (TiO 2} ) as the insulating fine particles 5a, the container 600 containing the nitrate aqueous solution as the reaction solution 500 is insulated with photocatalytic performance. The first electrode 2 on which the insulating fine particle layer 5d made of the sex fine particles (TiO ₂ ) was formed was charged, and ultraviolet rays were irradiated from an ultraviolet irradiator as a light source 700 in order to precipitate silver by a photoprecipitation method. In this way, silver, which is the conductive fine particles 5b, can be supported on _{TiO 2} which is the insulating fine particles 5a.

In the following examples, the electron emitting element 1 of the present invention will be described. It should be noted that this embodiment is an example and does not limit the present invention. The electron emitting element 1 used in the examples was manufactured as follows.

Process (1-1):
An aluminum substrate having a thickness of 0.5 mm is used as the first electrode 2, and the following is used to make the arrangement of the sea-island structure of the insulating portion 3 in angular parallel (FIG. 11 (d)) in the electron emitting region 7 of 5 mm × 5 mm. The sizes shown in Examples 1 to 3 and Comparative Example 1, the size shown in Example 4 below in order to form a round staggered pattern (FIG. 11 (a)) as the arrangement of the sea-island structure of the insulating portion 3, and the semiconductivity. In order to make the arrangement of the sea-island structure of part 5 angularly parallel (FIG. 11 (d)), masking was performed with the size shown in Example 5 below, and the current density was 1 A / in a 15 wt% sulfuric acid bath at 20 ° C. ± 1 ° C. The aluminum substrate was anodized at ^{dm 2 for 250 seconds.} Then, the insulating layer 3 having a thickness of 2 μm was prepared by sealing with distilled water (pH: 6.0, 90 ° C.) for about 30 minutes. Distilled water having a pH of 5.5 to 7.5 can be used at 90 to 100 ° C. for the sealing treatment.

Step (1-2):
Next, the insulating fine particle layer 5d was formed by the electrophoretic deposition method of the intermediate layer 5. The dispersed suspension solution 200 used for electrophoresis deposition was prepared as follows. 0.08 g of TiO ₂ particles (X-ray particle size: 200 nm), 0.02 g of iodine, and 100 ml of acetone were mixed and stirred for 30 minutes. Then, it was ultrasonically dispersed for 3 minutes to prepare a suspension solution (0.8 g / L) in which _{TiO 2 was dispersed.} Next, as shown in FIG. 7 (b), an aluminum plate (thickness 0.5 mm) is placed on the first electrode 2 and the counter electrode 400 on which the insulating layer 3 produced in the step (1-1) is formed on the cathode, and the voltage is applied. Approximately needle-shaped TiO2 particles were deposited on the exposed portion of the aluminum substrate at 10 V for 20 seconds. Here, the distance between the electrodes is 1 cm. The film thickness was 1.3 μm.

Step (1-3):
Next, the conductive fine particles were supported in the _{form of substantially needle-shaped TiO 2} particles by the light precipitation method shown in FIG. Using 100 ml of a 5 μmol / L silver nitrate aqueous solution as the reaction solution 500 containing the metal ions of the metal to be supported, the first electrode 2 having the insulating fine particle layer 5d formed up to the position where the insulating fine particle layer 5d is immersed is installed, and the insulating fine particles are installed. The light source 700 was irradiated with an ultraviolet lamp so that the layer 5d was exposed to ultraviolet rays. Due to the photocatalytic performance of titanium oxide, silver ions were reduced on TiO2 to generate silver nanoparticles, and supported particles 5c on which silver fine particles were supported were obtained.

This was air-dried overnight in a room temperature atmosphere to prepare a structure shown in FIG. 5 having an intermediate layer 5 composed of supported particles 5C.

Step (1-4):
Subsequently, using a magnetron sputtering apparatus, a layer thickness of 40 nm made of Au as a material and a range of 7 mm × 7 mm, which is one size larger than the element area, are sputtered on the intermediate layer 5 to form the second electrode 6. An example electron emitting device 1 was obtained.

[Example 1]
In the above step (1-1), the pitch p1, p2: 400 μm and the line width d1, d2: 200 μm shown in FIG. 11 (d) are set, and the area ratio of the semi-conductive portion 5 (area of the semi-conductive portion 5 / electron emission region). Area of 7 × 100): Formed so as to have an angular parallel sea-island structure of the insulating portion 3 having 75%, and the electron emitting element 1 was obtained by performing steps (1-2) to (1-4). It was.

[Example 2]
In the above step (1-1), the pitch p1, p2: 400 μm and the line width d1, d2: 100 μm shown in FIG. 11 (d) are set, and the area ratio of the semi-conductive portion 5 (area of the semi-conductive portion 5 / electron emission region). Area of 7 × 100): 44% of the insulating portion 3 is formed so as to have an angular parallel sea-island structure, and the electron emitting element 1 is obtained by performing steps (1-2) to (1-4). It was.

[Example 3]
In the above step (1-1), the pitch p1, p2: 500 μm and the line width d1, d2: 100 μm shown in FIG. 11 (d) are set, and the area ratio of the semi-conductive portion 5 (area of the semi-conductive portion 5 / electron emission region). Area of 7 × 100): Formed so as to have an angular parallel sea-island structure of the insulating portion 3 having 36%, and the electron emitting element 1 was obtained by performing steps (1-2) to (1-4). It was.

[Comparative Example 1]
In the above step (1-1), the insulating portion 3 is formed so that there is no sea-island structure and the area ratio of the semi-conductive portion 5 (area of the semi-conductive portion 5 / area of the electron emission region 7 × 100) is 100%. , Steps (1-2) to (1-4) were carried out to obtain an electron emitting element 1.

[Example 4]
In the above step (1-1), the pitch p3, p4: 400 μm and the diameter φ1: 200 μm shown in FIG. 11 (a) are set, and the area ratio of the semi-conductive portion 5 (area of the semi-conductive portion 5 / electron emission region 7 × 100). The electron emitting element 1 was obtained by forming the insulating portion 3 having a ratio of 61% so as to have a round staggered sea-island structure and performing steps (1-2) to (1-4).

[Example 5]
In the above step (1-1), the pitch p1, p2: 400 μm and the line width d1, d2: 50 μm shown in FIG. 11 (d) are set, and the area ratio of the semi-conductive portion 5 (area of the semi-conductive portion 5 / electron emission region). Area of 7 × 100): The electron emitting element 1 is formed by performing steps (1-2) to (1-4) so as to have an angular parallel sea-island structure of the semi-conductive portion 5 having 77%. Obtained.

[Comparative Example 2]
The electron discharge element 50 of FIG. 9 manufactured in the same manner as the embodiment shown in Patent Document 3 is shown.

The electrode substrate 52 had molybdenum deposited at 20 nm on the surface of a glass substrate having a thickness of 0.7 mm and a length and width of 41 mm × 45 mm by a sputtering method, further laminated with aluminum formed at 10 nm, and molybdenum formed again at 20 nm. It is a thing.

First, in the electrical insulating layer forming step, the electrical insulating layer 55 and the opening 56 are formed. A solution containing a photosensitive acrylic resin is applied to the surface of the electrode substrate 52 by a spin coating coating method to form a film, and the film is formed so as to have a film thickness of 2 μm after curing. The base polymer of the photosensitive acrylic resin is a polymer of methacrylic acid and glycidyl methacrylate, and the photosensitive portion dissolves in a developing solution. Specifically, an acrylic resin having a viscosity of 27 cp is prepared, and the prepared acrylic resin is applied to the surface of the cleaned electrode substrate 52 at a spin rotation speed of 1000 rpm. Subsequently, the electrode substrate 52 coated with the acrylic resin is heated to 100 ° C., and the solvent of the photosensitive acrylic resin and the solvent such as ethyl lactate are dried and heat-cured.

Next, the electrode substrate 52 coated with the acrylic resin is overexposed with a metal mask pattern for forming the opening 56. The opening 56A formed by the opening 56 is a square of 60 μm square. The metal mask pattern has a total of 18225 opening patterns formed in a region of 32.2 mm × 32.2 mm in length and width with 135 × 135 in length and width.

After the exposure, the acrylic resin exposed by superimposing the metal mask pattern is developed with an alkaline solution, here, a solution of tetramethylammonium hydrooxide. The alkaline solution etches the exposed portion of the acrylic resin to give an opening 56 of the desired shape.

Further, the acrylic resin in which the opening 56 is formed is heated by pure water after the developer remaining on the surface is washed, and is cured by a cross-linking reaction. The electrically insulating layer 55 and the electrode substrate 52, which are acrylic resins having the openings 56 formed therein, are placed in an oven and heated at 200 ° C.

In the next fine particle layer forming step, the fine particle layer 53 is formed. 1.5 g of n-hexane solvent is put into a 10 mL reagent bottle, and 0.25 g of silica particles as insulating fine particles 57A are put into the reagent bottle, and the reagent bottle is dispersed by an ultrasonic disperser. Here, the silica fine particles are Fame Silica C413 manufactured by Cabot Corporation with an average particle diameter of 50 nm. The surface of the silica fine particles is treated with hexamethylsidirazane. By applying to the disperser for 5 minutes, the silica fine particles are dispersed in an n-hexane solvent in a milky white color.

Subsequently, 0.06 g of silver nanoparticles as the conductive fine particles 57B are charged and similarly dispersed in an ultrasonic disperser. These silver nanoparticles are manufactured by Applied Nano Research Institute and have an average particle diameter of 10 nm with an insulating coating of alcoholate. Here, the dispersion liquid in which the silver nanoparticles are dispersed is referred to as the dispersion liquid A.

Similarly, 1.5 g of n-hexane solvent was put into a 10 mL reagent bottle, 0.25 g of fame silica C413 silica particles were put as insulating fine particles 57A, and the reagent bottle was similarly dispersed by an ultrasonic disperser. Let me. Next, 0.036 g of the silicone resin solution is added and similarly dispersed in an ultrasonic disperser. This silicone resin is a room temperature / moisture curing type SR2411 silicone resin manufactured by Toray Dow Corning. Here, the dispersion liquid in which the silicone resin is dispersed is referred to as the dispersion liquid B.

The dispersion liquid A is dropped onto the surface of the electrically insulating layer 55 having the opening 56 formed on the electrode substrate 52, and the first fine particle layer 531 is formed by a spin coating method. The electrode substrate 52 on which the first fine particle layer 531 is formed is heat-dried (hereinafter referred to as “temporary firing”) for 1 minute using a hot plate at 150 ° C. Further, a film is formed in the same manner using the dispersion liquid B to form the second fine particle layer 532. Similarly, the electrode substrate 52 on which the second fine particle layer 532 is formed is also heat-dried (hereinafter referred to as “main firing”) for 1 hour using a hot plate at 150 ° C.

The film forming condition by the spin coating method is that the dispersion liquid A or the dispersion liquid B is dropped onto the surface of the electrically insulating layer 55 while rotating at 500 rpm (hereinafter referred to as “RPM”), and then 3000 RPM. Rotate for 10 seconds at.

In the next removing step, the fine particle layer 53 formed in the opening 56A formed by the opening 56 is left as it is, and only the fine particle layer formed on the surface of the electrically insulating layer 55 is removed using a scraper. .. In order not to damage the electric insulating layer 55, here, the surface of the electric insulating layer 55 is scraped off by using a polypropylene blade, and the fine particle layer 53 formed in the opening 56A formed by the opening 56 is left as it is. , Only the fine particle layer formed on the surface of the electrically insulating layer 55 is removed. Fine particle dust generated during scraping is blown off with an air gun to clean it.

Next, in the film forming step, the thin film electrode 54 is formed. 1.0 g of ethanol solvent is placed in a 10 mL reagent bottle, 0.1 g of silica particles are charged as a spherical shield, and the mixture is dispersed for 5 minutes using an ultrasonic disperser. Here, the silica fine particles are fumed silica SE-5V manufactured by Tokuyama Co., Ltd. having an average particle diameter of 8 μm, and the surface of the silica fine particles is treated with hexamethylsidirazane. Here, the dispersion liquid in which the silica fine particles are dispersed is referred to as the dispersion liquid C.

The dispersion liquid C is dropped onto the surfaces of the electrically insulating layer 55 and the fine particle layer 53 formed on the electrode substrate 52, and the spherical shield is uniformly sprayed by using the spin coating method. After spraying, the electrode substrate 52 on which the electrically insulating layer 55 and the fine particle layer 53 formed on the electrode substrate 52 are formed is heated for 1 minute using a hot plate at 150 ° C. to evaporate the solvent.

A metal mask in which a region corresponding to the shape of the thin film electrode 54, specifically, a 35 mm × 35 mm square region in which the thin film electrode 54 is arranged is opened, is provided with an electrically insulating layer 55 and a fine particle layer on which a spherical shield is sprayed. The amorphous carbon layer 58 is deposited on the surface of 53 using a resistance superheated vapor deposition machine, and subsequently formed using a gold-palladium (hereinafter referred to as “Au-Pd”) target using a sputtering device. , Obtains an Au-Pd electrode film which is a source of the porous electrode layer 59A. The film thickness of the amorphous carbon layer 58 is 10 nm, and the film thickness of the electrode film of Au—Pd is 20 nm.

After removing the metal mask, the surface of the thin film electrode 54 is blown with dry air to remove the spherical shield. The electrode film of Au-Pd from which the spherical shield has been removed is the porous electrode layer 59A. The portion where the amorphous carbon layer 58 and the porous electrode layer 59A are not laminated due to the presence of the spherical shield is a hole for forming the hole 541 of the thin film electrode 54.

Subsequently, the metal mask used for forming the amorphous carbon layer 58 and the porous electrode layer 59A was re-stacked at the same position where the amorphous carbon layer 58 and the porous electrode layer 59A were laminated to form the porous electrode layer 59A. A solid electrode layer 59B made of Au—Pd is formed on the entire surface of the portion by a sputtering method. The film thickness of the solid electrode layer 59B is 20 nm. The solid electrode layer 59B is a thin film made of a metal material. After forming the solid electrode layer 59B, the metal mask is removed. By removing the metal mask, the solid electrode layer 59B is completed, and the thin film electrode 54 forming the surface of the electron emitting element 50 is formed. A hole 541 is formed in a portion where the amorphous carbon layer 58 and the porous electrode layer 59A are not laminated.

As described above, the electron emitting element 50 according to the second comparative example was manufactured.

[Evaluation]
Evaluation device:
FIG. 10 shows the measurement system used in the electron emission experiment. A voltage of Vd is applied between the first electrode 2 and the second electrode 6 of the electron emitting element 1 by the power supply 11A, and a voltage of Ve is applied to the counter electrode 12. The current flowing between the second electrode 6 and the power supply 11A is measured as the intra-element current Id, and the current generated in the counter electrode 12 is measured as the emission current Ie. An element evaluation was performed by arranging such a measurement system in the atmosphere.

Electron emission characteristics:
The measurement system of FIG. 10 will be described. The voltage applied to the first electrode 2 is defined as the drive voltage Vd, and the current value generated up to the second electrode 6 by applying the drive voltage Vd is defined as the in-device current Id. The counter electrode 12 was installed so as to face the second electrode 6, and the current value generated by the emitted electrons was defined as the emission current Ie. The ratio of the emission current Ie to the in-device current Id is expressed by the efficiency η (= Ie / Id). The gap between the recovery electrode and the second electrode 6 was 0.5 mm, and the voltage Ve of the counter electrode was 600 V. The drive voltage Vd applied to the first electrode 2 was 0 to 26 V, and the potential of the second electrode 6 was the ground potential.

Ten pieces were prepared for each of Examples 1 to 5 and Comparative Examples 1 and 2, and the maximum value of the emission current Ie of each of the 10 pieces was measured, and the variation within the 10 pieces was calculated.

[result]
The degree of variation in Example 1 was ± 40% with respect to the average value of 10 pieces. In Example 2, it was ± 38% with respect to the average value of 10 pieces. In Example 3, it was ± 43% with respect to the average value of 10 pieces. In Comparative Example 1, it was ± 65% with respect to the average value of 10 pieces. In Example 4, it was ± 35% with respect to the average value of 10 pieces. In Example 5, it was ± 41% with respect to the average value of 10 pieces. The largest emission current Ie out of 10 was 7 × ^10-6 A / cm ² . In Comparative Example 2, it was ± 47% with respect to the average value of 10 pieces. The largest emission current Ie out of 10 was 2 × ^10-6 A / cm ² .

If the area ratio of the semi-conductive portion 5 (area of the semi-conductive portion 5 / electron emission region 7 × 100) from Examples 1 to 5 and Comparative Example 1 to 80% is 30% to 80%, the variation in the emission current Ie can be suppressed. I understood. Further, it was found that the performance of Example 5 was improved in the emission current IE even though the configuration was simple as compared with Comparative Example 2. Although it is not clear about this, since the insulating portion is formed by the anodic oxidation of the first electrode, it is considered that the powder adhesion with the electrode is involved.

Further, the effective utilization rate of the coating liquid used for forming the insulating fine particle layer 5d in the steps (1-2) in Examples 1 to 5 is that the suspension solution 200 in which the insulating fine particles 5a are dispersed is the insulating fine particles. If 5a is replenished, it can be used after that, so it is 100%. When the fine particle layer 53 of Comparative Example 2 was formed by the spin coating method, the effective utilization rate of the coating liquid used in the spin coating was 10% or less because it also flowed out of the electron emitting element.

Since the electron emitting element according to the present invention does not involve electric discharge, ozone is not generated and stable atmospheric pressure operation is possible. Therefore, for example, a charging device for an image forming device such as an electrophotographic copier, a printer, or a facsimile, an electron beam curing device, an image display device in combination with a light emitting body, or an ion wind generated by emitted electrons. Can be suitably applied to a blower or the like by using the above.

The present invention is not limited to that described in each embodiment, and various modifications can be made within the scope of the claims. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.

The electron emitting element according to the present invention is, for example, a self-luminous device, emitted by combining with an image forming apparatus such as an electrophotographic copier, a printer, a facsimile, a charging device thereof, an electron beam curing apparatus, or a light emitting body. It can be used in various devices such as a cooling device by using the ion wind generated by electrons.

1 Electron emission element 2 1st electrode 3 Insulation part (insulation layer)
4 Dielectric layer 5 Semi-conductive part (intermediate layer)
5a Insulating fine particles 5b Conductive fine particles 5c Supported particles 5d Insulating fine particles 6 Second electrode 7 Electron emission region 11A Power supply (power supply unit)
11B Power supply 12 Opposite electrode 50 Electron emitting element 52 Electrode substrate 53 Fine particle layer 54 Thin film electrode 55 Electrically insulated layer 56 Opening 56A Opening 57A Insulating fine particles 57B Conductive fine particles 58 Amorphous carbon layer 59A Porous electrode layer 59B Solid electrode layer 100 Reaction vessel 200 Suspension solution 300 Power supply 400 Counter electrode 500 Reaction solution 600 Container 700 Light source

Claims (14)

An insulating portion provided between the first electrode, the second electrode, the first electrode and the second electrode, which has a predetermined opening, and the first electrode and the second electrode. A semi-conductive portion disposed in the opening is provided between the two.
An electron emitting element that emits electrons from the second electrode by applying a voltage between the first electrode and the second electrode.
Having the insulating portion in the electron emission region of the first electrode,
The insulating fine particles seen contains an electrically conductive fine particles and photocatalytic performance in semiconductive portions,
An electron emitting element , wherein the insulating portion is made of an oxide of the first electrode. An insulating portion provided between the first electrode, the second electrode, the first electrode and the second electrode, which has a predetermined opening, and the first electrode and the second electrode. A semi-conductive portion disposed in the opening is provided between the two.
An electron emitting element that emits electrons from the second electrode by applying a voltage between the first electrode and the second electrode.
Having the insulating portion in the electron emission region of the first electrode,
The insulating fine particles seen contains an electrically conductive fine particles and photocatalytic performance in semiconductive portions,
An electron emitting element, characterized in that the area ratio of the semiconductive portion is 30 to 80% in the electron emitting region of the first electrode. An insulating portion provided between the first electrode, the second electrode, the first electrode and the second electrode, which has a predetermined opening, and the first electrode and the second electrode. A semi-conductive portion disposed in the opening is provided between the two.
An electron emitting element that emits electrons from the second electrode by applying a voltage between the first electrode and the second electrode.
Having the insulating portion in the electron emission region of the first electrode,
The insulating fine particles seen contains an electrically conductive fine particles and photocatalytic performance in semiconductive portions,
The first electrode is an electron emitting element, characterized in that it is made of a metal plate on which an oxide film can be formed by anodic oxidation or a substrate on which the metal film is formed. An insulating portion provided between the first electrode, the second electrode, the first electrode and the second electrode, which has a predetermined opening, and the first electrode and the second electrode. A semi-conductive portion disposed in the opening is provided between the two.
An electron emitting element that emits electrons from the second electrode by applying a voltage between the first electrode and the second electrode.
Having the insulating portion in the electron emission region of the first electrode,
The insulating fine particles seen contains an electrically conductive fine particles and photocatalytic performance in semiconductive portions,
An electron emitting element, characterized in that the opening penetrates between the first electrode and the second electrode. The electron emitting element according to any one of claims 1 to 4, wherein the insulating portion exists not only above the surface of the first electrode but also inside the first electrode. The electron emitting element according to any one of claims 1 to 5, wherein the electron emitting region of the first electrode has a sea-island structure formed by the semi-conductive portion and the insulating portion. The electron emitting element according to claim 6 , wherein the sea-island structure has a parallel shape, a staggered shape, or an indefinite shape. Insulation part forming step of forming an insulation part having a predetermined opening on the first electrode,
A semi-conductive portion forming step of forming a semi-conductive portion which is an intermediate layer in the opening on the first electrode.
It has a second electrode forming step of forming a second electrode for emitting electrons on the semi-conductive portion and the insulating portion.
The semi-conductive portion forming step includes a step of forming the semi-conductive portion by electrophoresis deposition.
A method for manufacturing an electron emitting device, which comprises forming the insulating portion having the predetermined opening at least in the electron emitting region in the insulating portion forming step. The method for manufacturing an electron emitting device according to claim 8 , wherein the insulating portion is formed by anodic oxidation of the first electrode in the insulating portion forming step. In forming the insulating portion in the electron emitting region of the first electrode in the insulating portion forming step, the insulating portion is formed so that the insulating portion or the semi-conductive portion has a sea-island structure. The method for manufacturing an electron emitting element according to claim 8 or 9. The semi-conductive portion contains conductive fine particles and insulating fine particles, and the semi-conductive fine particles are made of supported particles supported on the insulating fine particles, according to any one of claims 8 to 10. The method for manufacturing an electron emitting element according to the above method. The method for manufacturing an electron emitting element according to claim 11 , wherein the conductive fine particles are supported on the insulating fine particles by a light precipitation method. The semi-conductive portion forming step
A step of forming an insulating fine particle layer on the first electrode on which the insulating portion having a predetermined opening is formed, and a step of forming an insulating fine particle layer.
The method for manufacturing an electron emitting element according to claim 11 , further comprising a step of supporting conductive fine particles in which the conductive fine particles are supported on the insulating fine particles constituting the insulating fine particle layer. In the electrophoresis deposition, the first electrode having the insulating fine particle layer having a predetermined opening formed in a suspension solution in which the insulating fine particles or the supporting particles are dispersed in a dispersion medium is used as an anode or a cathode. The insulating fine particle layer or the supporting particle layer constituting the semi-conductive portion is provided with a predetermined opening by immersing the particle layer together with the counter electrode, the cathode or the anode, and then applying a controlled voltage and / or current. The method for manufacturing an electron emitting element according to claim 13 , wherein the insulating portion is formed on the first electrode.

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