JP2007087643A - Manufacturing method of electron emission source, and electron emission source manufactured by the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electron emission source prevented from unevenness of brightness. <P>SOLUTION: First, only a plurality of glass particles having diameter within a prescribed range are taken out from that having variation of diameter. The plurality of glass particles are mixed in carbon nano-tube paste. On the carbon nano-tube paste, proportion of content, particle diameter, and degree of scatter of the plurality of glass particles are settled so that the glass particles are not combined into one body at heat treatment. The carbon nano-particles are heated on a cathode layer. At this time, heat treatment is applied in such a condition that only few glass particle out of the plurality of glass particles included in lowermost layer adheres to the cathode layer 2. As a result, since the few glass particles are almost uniformly scattered on the cathode layer 2, also bundles 33 of the plurality of carbon nano-tubes 3 are uniformly scattered. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing an electron emission source having carbon nanotubes and an electron emission source produced thereby.

  In recent years, electron emission sources having carbon nanotubes have been proposed as electron emission sources for thin panel display devices such as field emission displays (FEDs). Since the carbon nanotube has a large aspect ratio, electric field concentration tends to occur at the tip thereof. As a result, the electron emission source efficiently emits electrons with a low applied voltage. That is, an electron emission source having carbon nanotubes has good field emission characteristics. An example of an electron emission source having such a carbon nanotube is disclosed in Japanese Patent Laid-Open No. 2003-168355.

Various studies have been conducted on the standing shape of carbon nanotubes constituting the electron emission source and the efficiency of field emission. For example, Applied Physics Letters vol.80 number11 P2011-2013 “Field emission from dense, sparse, and pattered arrays of carbon nanofibers” can be used to produce a display with good field emission and no uneven brightness. It is disclosed that it is important to disperse and dispose a plurality of carbon nanotubes standing on the cathode layer.
JP 2003-168355 A Applied Physics Letters vol.80 number11 P2011-2013 ”Field emission from dense, sparse, and pattered arrays of carbon nanofibers”

  The conventional electron emission source has a drawback that uneven luminance occurs because the number of effective bright spots is small. Such brightness unevenness is due to the presence of unevenness in the heights of the tips of the plurality of carbon nanotubes, and even when the same voltage is applied to the plurality of carbon nanotubes, This is thought to be caused by the fact that some of them do not release. In addition, it is considered that some of the carbon nanotubes are locally biased, which is a cause of uneven brightness.

  More specifically, when a method of coating a carbon nanotube material prepared in another place in a film shape on a glass substrate, such as a printing method or a spray method, is used, a plurality of carbon nanotubes are raised. It is not easy to distribute the parts evenly. Therefore, uneven brightness occurs in a display device using an electron emission source created by a printing method or a spray method.

  Further, as disclosed in Japanese Patent Application Laid-Open No. 2003-168355, even when a plurality of carbon nanotubes are erected by a process of peeling a tape attached to the plurality of carbon nanotubes, the plurality of carbon nanotubes are evenly dispersed. It is not easy to arrange. Therefore, even in this case, luminance unevenness occurs.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electron emission source manufacturing method in which the occurrence of uneven brightness is prevented and an electron emission source manufactured thereby.

  In the method for manufacturing an electron emission source according to the present invention, first, a carbon nanotube paste including a plurality of glass particles and a plurality of carbon nanotubes is prepared. Next, a carbon nanotube paste is attached to the cathode layer. Thereafter, the carbon nanotube paste is heated to form a plurality of droplets in which a plurality of glass particles are melted. Next, a carbon nanotube layer in which a plurality of droplets are cured and fixed to the cathode layer is formed. Thereafter, the upper layer portion of the carbon nanotube layer is removed using a peeling process.

  Regarding the carbon nanotube paste described above, the ratio, particle size, and dispersity of the plurality of glass particles are set to such an extent that the glass particles are not integrated in the heating step. Further, the temperature and time of the heating step are set so that only some of the glass particles located in the lowermost layer among the plurality of glass particles adhere to the cathode layer. Further, in the peeling process, glass particles located above some glass particles fixed to the cathode layer are removed and a plurality of carbon nanotubes are erected.

  According to the above-mentioned manufacturing method, some glass particles fixed to the cathode layer are arranged almost uniformly on the cathode layer. Therefore, a plurality of bundles of carbon nanotubes extending from the remaining carbon nanotube layer are also uniformly distributed, and electric field concentration tends to occur at the respective tips of the plurality of bundles of carbon nanotubes. That is, a light emission point group in which individual light emission points are evenly dispersed is formed. Therefore, the variation in luminance of the light emitting point group is improved.

The following electron emission source can be obtained by the above method for manufacturing an electron emission source.
An electron emission source according to one aspect of the present invention is provided with a cathode layer, a plurality of glass portions that are uniformly distributed on the cathode layer, and a plurality of glass portions that are fixed to the cathode layer, and a plurality of glass portions that are exposed in the cathode layer. The carbon nanotube layer formed in a region between a plurality of glass parts, and a plurality of carbon nanotubes that are uniformly distributed over the entire surface of the carbon nanotube layer and extend upward from the carbon nanotube layer ing.

  An electron emission source according to another aspect of the present invention is disposed so as to cover the cathode layer, the plurality of glass portions that are uniformly distributed on the cathode layer, and fixed to the cathode layer, and the plurality of glass portions and the cathode layer. The formed carbon nanotube layer includes a plurality of carbon nanotubes that are uniformly distributed over the entire surface of the carbon nanotube layer and extend upward from the carbon nanotube layer.

Hereinafter, a method for manufacturing an electron emission source according to an embodiment of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram showing an electron emission source manufactured by the method for manufacturing an electron emission source according to Embodiment 1 of the present invention. As shown in FIG. 1, the electron emission source of the present embodiment includes a glass substrate 1 and a cathode layer 6 formed on the glass substrate 1. On the cathode layer 6, a plurality of frit glass portions 4 are arranged evenly dispersed. A carbon nanotube layer 2 exists between the frit glass portions 4. A bundle 33 of a plurality of carbon nanotubes 3 extends from the carbon nanotube layer 2 along a direction substantially perpendicular to the main surface of the glass substrate 1. Note that the upper portions of the plurality of frit glass portions 4 are exposed from the carbon nanotube layer 2.

  In addition, the plurality of bundles 33 are arranged evenly distributed on the cathode layer 6. Thereby, field emission due to electric field concentration tends to occur at the tips of the plurality of carbon nanotubes 3 constituting the bundle 33. Therefore, the number of effective bright spots of the electron emission source is increased, and the field emission mode of the plurality of carbon nanotubes 3 is substantially uniform along the cathode layer 6. As a result, the occurrence of uneven brightness is prevented.

  FIG. 2 is a diagram showing another example of the electron emission source according to the first embodiment of the present invention. As shown in FIG. 2, the electron emission source of another example of the present embodiment includes a glass substrate 1 and a cathode layer 6 formed on the glass substrate 1. On the cathode layer 6, a plurality of frit glass portions 4 are arranged uniformly dispersed. The carbon nanotube layer 2 is formed so as to completely cover the plurality of frit glass portions 4 and to cover the main surface of the cathode layer 6 in a region between the plurality of frit glass portions 4. A bundle 33 of carbon nanotubes 3 extends from the main surface of the carbon nanotube layer 2 along a direction substantially perpendicular to the main surface of the glass substrate 1. Focusing only on the bundle 33 extending from the carbon nanotube layer 2 positioned above the plurality of frit glass portions 4, the bundle 33 is arranged on the cathode layer 6 so as to be evenly dispersed. Therefore, the same effect as that obtained by the electron emission source shown in FIG. 1 can be obtained by the electron emission source of another example shown in FIG.

Next, a method for manufacturing the electron emission source of the present embodiment will be described.
In the method for manufacturing an electron emission source according to the present embodiment, first, a paste containing a frit glass powder having a uniform particle size is prepared. For this purpose, a fine particle powder of frit glass is prepared. Next, the fine powder of the frit glass is pulverized by a ball mill using a solvent. However, a bead mill may be used instead of the ball mill.

  Further, terpineol is used as the solvent. After adding 20 g of low melting point bismuth glass to 50 g of terpineol, the bismuth glass is dispersed in the solvent using an ultrasonic homogenizer (600 W). The ultrasonic homogenizer is used for about 10 minutes because the temperature of the solvent rises if used for a long time. By the above process, a slurry in which bismuth glass is dispersed in a solvent is obtained.

  The slurry is then transferred to a ball mill container. Thereafter, 10 g of zirconia balls (diameter 3 mm) are added to the slurry in the ball mill container. Next, an additional 20 g of solvent is added to the slurry in the ball container. Thereafter, ball milling is performed. At this time, a planetary ball mill is used to improve the grinding efficiency.

  In the ball mill pulverization step, the particle size of the bismuth glass is measured every predetermined time in order to control the particle size of the bismuth glass. If it is confirmed by the measurement that the average particle diameter of the bismuth glass has reached a value within the desired range, the ball milling is finished.

  Next, classification of the slurry containing the bismuth glass is performed using a centrifuge. In the classification, first, the centrifuge is rotated at a relatively high speed, and the supernatant liquid of the slurry is removed from the slurry before the entire slurry is completely submerged. Thereby, the frit glass particles having a relatively small particle size are removed from the slurry. Next, the centrifuge rotates at a relatively low speed, and the fast-sunk frit glass is removed from the slurry. Thereby, the frit glass particles having a relatively large particle size are removed from the slurry. As a result, the width of the particle size of the frit glass is narrowed. The average particle size of the frit glass is about 10 μm to 1 μm or less.

  By the method as described above, a frit glass powder having a narrow particle size distribution is prepared, and this frit glass powder is included in the carbon nanotube paste.

Next, a method for producing a carbon nanotube paste will be described.
In addition to the carbon nanotubes, the carbon nanotube paste includes a dispersant for improving the dispersibility of the carbon nanotubes, the above-mentioned frit glass powder for fixing the carbon nanotubes to the cathode layer, and for improving the conductivity. Conductive material powder is mixed. The conductive material powder is, for example, silver powder or ITO powder. The dispersant and the conductive material powder may not be mixed in the carbon nanotube paste.

  Furthermore, an organic solvent for dissolving the entire carbon nanotube paste, a resin material for adjusting the viscosity of the carbon nanotube paste, and the like are added to complete the carbon nanotube paste for screen printing.

  In the present embodiment, a screen printing method is used as a method of forming the carbon nanotube layer, but instead, a spray coater or an ink jet spin coat may be used. Also, photolithography is used for pattern formation of the carbon nanotube layer.

  Examples of the carbon nanotube include SWCNT (Single-Walled Carbon Nanotube), DWCNT (Double-Walled Carbon Nanotube), and MWCNT (Multi-Walled Carbon Nanotube). The diameters of these carbon nanotubes have a fairly wide width from 10 nm or less to 50 nm or more. In addition, the properties of carbon nanotubes vary depending on the surface state, crystallinity, degree of purification, production method, and the like.

  In this embodiment, since a carbon nanotube paste for screen printing is created, a carbon nanotube with a small diameter is selected among MWCNTs having good emission characteristics in FED (Field Emission Display). Most of the carbon nanotubes selected have a diameter of 5 nm or less or 10 nm or less.

  In addition, a CVD (Chemical Vapor Deposition) method is selected as a carbon nanotube manufacturing method in consideration of industrial productivity. In general, carbon nanotubes produced by the CVD method tend to be bundles when the production rate is high, and many of them have pill-like particle shapes. However, these carbon nanotubes are tube-like when viewed microscopically.

  Also in the present embodiment, the pill-like carbon nanotube as described above is used. Carbon nanotubes are intertwined into a cotton shape, and the size of each pill is about several tens to several hundreds of microns.

  Next, the pills of the carbon nanotubes are dissolved in the organic solvent terpineol. Since terpineol has a high boiling point, it is a solvent generally used by screen printing. In the screen printing method, in addition to this, BCA (butyl carbitol acetate) or BC (butyl carbitol) is also generally used.

  Further, since carbon nanotubes have low wettability with respect to terpineol, a predetermined amount of a dispersant is further added to the mixture of terpione and carbon nanotubes after the carbon nanotubes have been put into the terpione. Next, after the mixed solution is lightly mixed, a process of dispersing the aggregated particles using an ultrasonic homogenizer (600 W output) is performed for about 10 minutes.

  Thereafter, the carbon nanotubes are dispersed in terpineol, and a dispersion liquid containing carbon nanotubes having an average particle size of about 10 μm is obtained. This dispersion is placed in a planetary ball mill container, and the carbon nanotubes are pulverized. During the pulverization process, the particle size distribution of the carbon nanotubes is measured every predetermined time (about 30 minutes to 1 hour), and the pulverization process ends when carbon nanotubes having a desired particle diameter are obtained. Thereby, a carbon nanotube slurry is formed.

  The aforementioned carbon nanotube slurry has a larger amount of organic solvent than the carbon nanotube paste in order to improve the pulverization efficiency. For this purpose, the solvent is separated from the carbon nanotube slurry using a centrifuge capable of high-speed rotation (10,000 rotations or more), and the carbon nanotube slurry is concentrated.

  Next, a part of the solution is baked, and the ratio of carbon nanotubes contained in the organic solvent is measured. Next, the classified frit glass slurry and the resin are added to the carbon nanotube slurry to produce a carbon nanotube paste. Thereafter, the carbon nanotube paste is processed with a kneader, whereby the materials in the carbon nanotube paste are mixed, and the bubbles in the carbon nanotube paste are discharged (defoamed). Next, a roll mill is used to modify the carbon nanotube paste to complete a screen printing paste.

  Next, a method for manufacturing an electron emission source using a carbon nanotube paste will be described.

  In the manufacturing process of the electron emission source of the present embodiment, first, a cathode layer is formed on a glass substrate. Next, the carbon nanotube paste is applied on the cathode layer by a printing method or a spray method. Thereafter, a heat treatment of the carbon nanotube layer is performed. Next, the tape is attached to the carbon nanotube layer and then peeled off to stand up the plurality of carbon nanotubes. Thereby, the bundle of the plurality of standing carbon nanotubes is uniformly dispersed on the cathode layer. As a result, the field emission efficiency is improved, and variations in luminance are prevented.

  A method for manufacturing an electron emission source of a field emission display using the carbon nanotube paste prepared as described above will be specifically described below.

  First, the cathode layer 6 is formed on the glass substrate 1. As a material for the cathode layer, for example, transparent indium tin oxide (ITO) is used.

  Actually, when the cathode layer 6 is formed, an indium tin oxide film is formed on the glass substrate 1. Thereafter, the indium tin oxide film is etched to form the cathode layer 6 having a predetermined pattern. A cathode layer 6 made of silver may be formed on the glass substrate 1 by a printing method.

  Next, a carbon nanotube paste is applied on the cathode layer 6 by a printing method, a spray method, an ink jet method or the like. Thereafter, the cathode layer 6 and the carbon nanotube layer 2 are fixed by firing.

  In the carbon nanotube paste used in the above-described printing method, in addition to the carbon nanotubes, a dispersant for dispersing the carbon nanotubes 3 in the paste is mixed. As the dispersant, what is generally called a basic comb polymer dispersant is used. In addition, when the carbon nanotube 3 excellent in dispersibility is used, a dispersing agent does not need to be used. The carbon nanotubes 3 excellent in dispersibility are considered to be formed due to the influence of the amorphous layer on the surface. In the carbon nanotube paste, a low melting point frit glass for fixing the carbon nanotube 3 to the cathode layer 6 is mixed.

  In addition, in order to improve the electroconductivity of a carbon nanotube, the metal matrix (metal particle) or electroconductive ITO powder may be mixed in the carbon nanotube paste. Further, when the screen printing method is used, a resin for improving printing performance may be mixed in the carbon nanotube paste. As the resin, ethyl cellulose generally used in screen printing is used. An acrylic resin or the like may be used instead of ethyl cellulose. Furthermore, a solvent such as BC (butyl carbitol) or BCA (butyl carbitol acetate) is included in the carbon nanotube paste in order to adjust the overall viscosity of the carbon nanotube paste and improve fluidity and ease of drying. May be mixed.

  A carbon nanotube paste in a slurry state is formed on the cathode layer 6 by attaching the carbon nanotube paste as described above to the cathode layer 6 using a method such as coating, printing, or spraying. Thereafter, the carbon nanotube paste in a slurry state is dried by heating, and the carbon nanotube layer 2 is formed on the cathode layer 6 as shown in FIG. In this state, frit glass particles 5 are scattered in the carbon nanotube layer 2. In FIG. 3, since the resin solvent is evenly dissolved in the carbon nanotube paste, it is evenly dispersed throughout the carbon nanotube layer 2 after the heating step. In FIG. 3, the drawing of the carbon nanotube 3 is omitted.

  Next, when the dried carbon nanotube layer 2 is heated, the solvent is first evaporated. Thereafter, by further heating, the resin is decomposed and the frit glass particles 5 are melted. The frit glass particles 5 are melted and then cured, and the carbon nanotubes 3 and the cathode layer 6 are fixed.

  In the manufacturing method of the electron emission source of the present embodiment, the vitrification temperature (softening point) of the frit glass particles 5 is lower than the softening point of the glass substrate 1. In order to form a plurality of frit glass portions 4 fixed to the cathode layer 6 as shown in FIGS. 1 and 2, it is desirable that the melted frit glass particles have low fluidity. When the frit glass has high fluidity, the molten frit glass droplets flow so as to cover the entire main surface of the glass substrate 1 to form a frit glass film extending in parallel with the main surface of the glass substrate 1. This is because the carbon nanotubes 3 cannot emit electrons. Accordingly, as frit glass, a material having low fluidity when melted and having a softening point lower than a material used for the glass substrate 1 (for example, a high strain point glass called PD-200), such as bismuth glass, is used. It is desirable to be used. Note that bismuth glass has a softening point of 350 ° C. to 550 ° C., but in this embodiment, a softening point of about 500 ° C. is used.

  After the dried carbon nanotube layer 2 as shown in FIG. 3 is formed, the carbon nanotube layer 2 is baked at a temperature of about 400 ° C. in the atmosphere in order to decompose the resin. Thereafter, the frit glass is heat-treated and melted at a temperature higher than 400 ° C. At this time, the carbon nanotube layer 2 is heat-treated at a temperature higher by about 10 ° C. to 20 ° C. than the softening point of the frit glass for a short time ((about several minutes to about 20 minutes).

  As a result, depending on the glass composition, without flowing out, for example, as shown in FIG. 4, only the lower part of the frit glass particles 5 in contact with the cathode layer 2 melts, and the frit glass particles 5 have a conical shape. Harden. Further, the frit glass particles 5 react with the carbon atoms constituting the carbon nanotubes 3 in the vicinity thereof to be in a droplet state. However, if the heating temperature and the heating time are adjusted, the frit glass in the form of droplets does not flow until they contact each other, and a conical frit glass portion 4 as shown in FIGS. 1 and 2 is formed. The In plan view, as shown in FIGS. 5 and 6, the plurality of frit glass portions 4 are independently and evenly distributed on the glass substrate 1. Thereafter, the firing of the carbon nanotube layer 2 is completed.

  After the carbon nanotube layer 2 is formed, an insulating layer for forming a triode structure is formed on the cathode layer 6. Typical examples of the method of forming the insulating layer include a method of forming silicon oxide by CVD (chemical vapor deposition), a method of forming a dielectric glass layer by printing, and a polymer insulating layer made of a silicon ladder polymer. There are new ways to do this. When the insulating layer covers the carbon nanotube 3, a through hole is opened in the insulating layer by etching or the like to expose the carbon nanotube 3. Thereafter, a gate electrode is formed on the insulating layer. The above-described tripolar structure will be described in detail in Embodiment 4 with reference to FIG.

  Next, when the carbon nanotube layer 2 is subjected to the tape peeling process, due to the difference between the property of the carbon nanotube 3 and the property of the frit glass portion 4, as shown in FIG. 1 and FIG. Standing carbon nanotubes 3 are formed so as to protrude from the layer 2.

  FIG. 6 shows a real image of the distribution state of the carbon nanotubes 3 and the frit glass portion 4 on the cathode layer 2 after the frit glass particles 5 are melted.

  It is important to make the distance between the bundles 33 of the plurality of carbon nanotubes 3 uniform so that electric field concentration occurs at the tip of each bundle 33 of the carbon nanotubes 3. Therefore, the particle diameter of the frit glass particles 5, the ratio (mixing ratio) of the frit glass particles 5 in the carbon nanotube paste, and the carbon nanotubes so that the frit glass portions 4 are uniformly dispersed on the cathode layer 6. It is necessary to adjust the degree of dispersion of the frit glass particles in the paste.

  Further, when the carbon nanotube paste is fired, the organic solvent and the resin in the carbon nanotube paste burn and disappear, so that the carbon nanotube 3 and the frit glass portion 4 remain on the cathode layer 6. In the carbon nanotube layer 2, it is considered that unburned amorphous carbon after decomposition of the resin, a dispersant that cannot be completely burned, and an inorganic component present in the carbon nanotube as impurities remain.

  In addition, the method of adjusting the particle diameter, the ratio, and the dispersion degree of the frit glass particles 5 in the carbon nanotube paste to appropriate values can be obtained by experiments. The manufacturing method of the electron emission source according to the present embodiment has a feature in this process, and thereby, the frit glass portions 4 are uniformly distributed between the bundles 33 of the carbon nanotubes 3. A state electron emission source is formed.

  In the present embodiment, the particle diameters of the frit glass particles and the carbon nanotubes are 1 μm or less so that the flatness of the carbon nanotube layer 2 is 1 μm or less in average roughness. As the frit glass particles, low melting point bismuth glass (softening point of about 500 ° C.) that melts at a temperature at which the glass substrate 1 does not deform is used. Since the low melting point lead glass has high reactivity with the carbon nanotubes and low viscosity, it flows out when it melts and covers the lower part of the carbon nanotube layer 2. Therefore, in the present embodiment, bismuth glass is used instead of the commonly used lead glass.

  When the carbon nanotube paste is fired for a short time of about 10 minutes at a temperature about 10 ° C. higher than the softening point temperature of the frit glass particles, as shown in FIGS. 1, 2, and 4, Depending on the type, the portion in contact with the cathode layer 6 melts, spreads along the main surface of the glass substrate 1, and adheres to the cathode layer 6. On the other hand, each of the frit glass particles 5 scattered between the carbon nanotubes 3 without being in contact with the cathode layer 6 is slightly melted and contracted at the outer peripheral portion, but is bonded to the adjacent frit glass particles 5. Without remaining independently.

  Further, as described above, when the surface treatment was performed on the entire carbon nanotube layer 2 formed as described above by the peeling process using the adhesive tape, it was fused to the cathode layer 6 as shown in FIG. A plurality of frit glass portions 4, a carbon nanotube layer 2 remaining on the cathode layer 6 between the plurality of frit glass portions 4, and a bundle 33 of a plurality of carbon nanotubes 3 erected from the surface of the carbon nanotube layer 2; A structure having is obtained. This structure is a structure in which the carbon nanotube layer 2 remains in a layer shape in all regions other than the plurality of frit glass portions 4 that are dispersed and arranged on the surface of the cathode layer 6. 33 are also uniformly distributed throughout the cathode layer 2. As shown in FIG. 2, when the carbon nanotube layer 2 continuously covering the surface of the frit glass portion 4 and the surface of the cathode layer 6 remains, the carbon nanotube layer above each of the plurality of frit glass portions 4. 2 and a bundle 33 standing from the carbon nanotube layer 2 positioned immediately above the cathode layer 6 and between the plurality of frit glass portions 4 are formed. In this structure, when attention is paid only to the bundle 33 standing up from the carbon nanotube layer 2 above each of the plurality of frit glass portions 4, the bundle 33 of the plurality of carbon nanotubes 3 is uniformly distributed on the cathode layer 2. The structure is equivalent to the above structure.

Next, a method for creating the structure shown in FIG. 1 and the structure shown in FIG. 2 will be described.
First, after the carbon nanotube paste is dried at a temperature of 120 ° C., the resin component is decomposed in the air at a temperature of about 350 ° C. to 400 ° C. for 30 minutes to several hours. Thereby, the baked carbon nanotube layer 2 is obtained. When frit glass that does not melt under the above-mentioned temperature conditions is used, the carbon nanotube layer 2 is fired for about 10 minutes at a temperature of 400 ° C. or higher in a nitrogen atmosphere in order to melt the frit glass.

  Depending on the temperature conditions of this firing step, a structure in which a plurality of frit glass portions 4 are exposed from the carbon nanotube layer 2 as shown in FIG. 1, and a carbon covering each of the plurality of frit glass portions 4 as shown in FIG. The structure in which the nanotube layer 2 is formed is formed. In general, when the temperature of the resin decomposition process is high or when the time of the resin decomposition process is long, a structure in which the plurality of frit glass portions 4 are exposed from the carbon nanotube layer 2 is easily formed, and the temperature of the resin decomposition process is high. When it is low or when the time of the resin decomposition process is short, a structure in which the carbon nanotube layer 2 covers the plurality of frit glass portions 4 is easily formed as shown in FIG. The reason why the carbon nanotube layer 2 having a different structure depending on the temperature and time of the firing step is considered to be the influence of the remaining amorphous carbon at the present stage.

  The length of the material of the carbon tube is not particularly limited, but what is generally said to be several microns to several tens of microns is used. In addition, the carbon nanotubes are entangled in a hairball shape, and some of them are loose. For this reason, upright portions of 10 μm or less are formed after the raising treatment, and many upright portions of 5 μm or less are seen in them.

  In order to disperse and arrange the plurality of frit glass portions 4 described above, the average particle size of the raw material frit glass particles is preferably 0.5 μm to 5 μm. When the frit glass particles are brought into close contact with the cathode layer 6 together with the metal particles and the carbon particles, the average particle size of the frit glass particles is preferably smaller than 0.5 μm. Accordingly, the height of the frit glass portion 4 remaining on the surface of the cathode layer 6 is 0.5 μm to 5 μm when only frit glass particles are used, and metal particles and carbon particles are used together with the frit glass particles. In this case, it is 0.5 μm or less. Further, the distance between the frit glass particles and the metal particles is preferably 1 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less.

The characteristics of the method for manufacturing the electron emission source according to the present embodiment will be described below.
Regarding the carbon nanotube paste, the ratio, the particle size, and the degree of dispersion of the plurality of frit glass particles 5 are set such that the frit glass particles 5 are not integrated with each other by heat treatment. The heat treatment temperature and time are set such that only some of the frit glass particles 5 located in the lowermost layer among the plurality of frit glass particles 5 are fixed to the cathode layer 6. In the peeling process of the cathode layer 6, all the frit glass particles 5 positioned above the plurality of frit glass portions 4 fixed to the cathode layer 6 are removed, and the structure shown in FIGS. 1 and 2 is obtained. .

Embodiment 2. FIG.
In the present embodiment, carbon particles are mixed in the carbon nanotube paste. However, the method for producing the carbon nanotube paste is the same as that described in the first embodiment. The carbon particles in the carbon nanotube do not adhere to the cathode layer 6. Therefore, a structure in which the carbon nanotube layer 2 is fixed to the cathode layer 6 is formed using very fine frit glass particles having an average particle diameter of 0.5 μm or less. In the present embodiment, the mixing ratio of the carbon particles, the frit glass particles, and the carbon nanotubes is adjusted so that the bundle 33 of the carbon nanotubes 3 is uniformly dispersed. However, the temperature and time of the heat treatment of the carbon nanotube layer of the present embodiment are the same as the temperature and time in the method of creating the carbon nanotube layer of the first embodiment.

Embodiment 3 FIG.
In the present embodiment, metal particles are mixed in the carbon nanotube paste. However, the method for producing the carbon nanotube is the same as that described in the first embodiment.

  When metal particles are mixed in the carbon nanotube, it is desirable to use silver particles having good contact with the cathode layer 2 as the metal particles. In this case, when the carbon nanotube paste is baked at a temperature of 400 ° C. or higher, silver and carbon nanotubes react and a large number of carbon nanotubes and silver disappear. Therefore, it is necessary to select a frit glass particle having a low softening point (400 ° C. or lower). Also in the present embodiment, as in the case where the carbon nanotube paste mixed with the carbon particles of the second embodiment is used, the intervals between the bundles 33 of the carbon nanotubes 3 are evenly dispersed. The mixing ratio of silver grains, frit glass particles, and carbon nanotubes is adjusted. However, the temperature and time of the heat treatment of the carbon nanotube layer of the present embodiment are the same as the temperature and time in the method of creating the carbon nanotube layer of the first embodiment.

Embodiment 4 FIG.
Next, a field emission display manufactured using the electron emission source of Embodiment 1 will be described.

  The field emission display has a cathode layer 6 that supplies electrons to the carbon nanotubes, an anode layer (not shown) that collides with electrons emitted from the electron emission source, and whether or not electrons are emitted from the electron emission source. It has a triode structure consisting of the gate electrode 8 that determines whether or not.

  In the tripolar structure shown in FIG. 7, an electron emission source having the structure shown in FIG. 1 is incorporated in a field emission display. The electron emission source shown in FIG. 7 has a glass substrate 1, a frit glass portion 4, a carbon nanotube layer 2, a frit glass portion 4 and an insulating layer 7 surrounding the carbon nanotube layer 2. Further, although not shown, the fluorescent plate is formed to face the electron emission source.

  When a voltage is applied between the cathode layer 6 and the anode layer described above and the potential of the gate electrode 8 exceeds the threshold value, electrons are emitted from the respective tips of the plurality of carbon nanotubes 3. The gate electrode 8 is an electrode that performs control related to display such as control for determining whether or not to emit electrons from the carbon nanotube 3 and control for adjusting the amount of electrons emitted from the carbon nanotube 3.

  The thickness of the insulating layer 7 is 10 μm or less, and the size of the opening 8 a of the gate electrode 8 is about several tens of μm. Therefore, the length of the upright portions of the plurality of carbon nanotubes 3 is several μm, and if it is longer than that, a short circuit occurs between the cathode layer 6 and the gate electrode 8.

  Further, the height of the crest of the frit glass portion 4 is specified to be 0.2 μm or more and 7 μm or less. When the peak height of the frit glass portion 4 is smaller than 0.2 μm, the size of the uneven shape is too small. Therefore, the standing parts of the carbon nanotubes 3 cannot be dispersed and arranged uniformly. Further, when the height of the peak of the frit glass portion 4 is larger than 7 μm, the uneven shape is too large. Therefore, the variation in the height of the carbon nanotubes 3 formed on the frit glass portion 4 becomes large. As a result, there is a possibility that the carbon nanotube 3 having a tip height higher than that of the insulating layer exists. Therefore, a short circuit may occur between the cathode layer 6 and the gate electrode 8.

  In addition, the field emission display is a display that is easily detected even by a minute defect by the human eye. Therefore, if there is even one defect, the defect becomes very conspicuous. Therefore, the field emission display is required to have no defects. As a result, the length of the standing part of the carbon nanotube 3 is desirably 7 μm or less.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

2 is a cross-sectional view of the electron emission source of Embodiment 1. FIG. FIG. 6 is a cross-sectional view of another example of the electron emission source according to the first embodiment. It is a cross-sectional schematic diagram of the carbon nanotube layer printed on the glass substrate. It is a cross-sectional schematic diagram of the carbon nanotube layer on the glass substrate after the several frit glass particle fuse | melts. The plane schematic diagram of the several frit glass part which remained on the glass substrate is shown. 3 is a photograph showing the distribution of carbon nanotubes and a plurality of frit glass portions on a glass substrate. It is a cross-sectional schematic diagram of the field emission display of an embodiment.

Explanation of symbols

  1 glass substrate, 2 carbon nanotube layer, 3 carbon nanotube, 4 frit glass part, 5 frit glass particle, 6 cathode layer, 7 insulating layer, 8 gate electrode.

Claims (10)

Providing a carbon nanotube paste comprising a plurality of glass particles and a plurality of carbon nanotubes;
Attaching the carbon nanotube paste to the cathode layer;
Heating the carbon nanotube paste to form a plurality of droplets in which the plurality of glass particles are melted;
Curing the plurality of droplets to form a carbon nanotube layer secured to the cathode layer;
Removing the upper layer portion of the carbon nanotube layer using a peeling process,
Regarding the carbon nanotube paste, the ratio of the plurality of glass particles, the particle diameter, and the degree of dispersion are set to such an extent that the glass particles are not integrated in the heating step.
The temperature and time of the heating step are set so that only some of the glass particles located in the lowermost layer of the plurality of glass particles adhere to the cathode layer,
In the peeling process, an electron emission source manufacturing method in which glass particles positioned above some glass particles fixed to the cathode layer are removed and the plurality of carbon nanotubes are erected. The cathode layer is formed on a glass substrate;
The electron emission source manufacturing method according to claim 1, wherein the plurality of glass particles have a softening point lower than a softening point of the glass substrate.   The method of manufacturing an electron emission source according to claim 1, wherein the plurality of glass particles include a plurality of bismuth glass particles.   The method of manufacturing an electron emission source according to claim 1, wherein some glass particles fixed to the cathode layer are exposed in the carbon nanotube layer.   The method of manufacturing an electron emission source according to claim 1, wherein some glass particles fixed to the cathode layer are covered with a remaining portion of the carbon nanotube layer.   The method of manufacturing an electron emission source according to claim 1, wherein the carbon nanotube paste includes metal particles or carbon particles.   The manufacturing method of the electron emission source of Claim 1 whose height after hardening of some glass particles located in the said lowermost layer is 0.2 micrometer-7 micrometers. A cathode layer;
A plurality of glass portions arranged uniformly distributed on the cathode layer, and fixed to the cathode layer;
A carbon nanotube layer formed in a region between the plurality of glass portions so that the plurality of glass portions are exposed in the cathode layer;
An electron emission source, comprising: a plurality of carbon nanotubes arranged uniformly distributed over the entire surface of the carbon nanotube layer and extending upward from the carbon nanotube layer. A cathode layer;
A plurality of glass portions arranged uniformly distributed on the cathode layer, and fixed to the cathode layer;
A carbon nanotube layer formed to cover the plurality of glass portions and the cathode layer;
An electron emission source, comprising: a plurality of carbon nanotubes arranged uniformly distributed over the entire surface of the carbon nanotube layer and extending upward from the carbon nanotube layer.   10. The electron emission source according to claim 8, wherein a height of the plurality of glass portions is 0.2 μm to 7 μm.