JP2011049095A - Fluorescent display device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent display device with a phosphor layer whose light emitting property hardly deteriorates and which is hardly peeled from an anode. <P>SOLUTION: A container part 1 has the anode 5 formed on the inner face of an anode substrate 2. Adhesive particles 12 are provided in layers on the anode, and the phosphor layer 7 is formed thereon. The container part 1 has a cathode 8 formed on the inner face of an cathode substrate 3 with a carbon nanotube 9. The adhesive particles are formed of ultrafine powder silica whose particle sizes are smaller than phosphor particle sizes, for example. The phosphor layer adhered to the anode is hardly peeled, gas is hardly generated in the phosphor layer including no metal oxide when emitted electrons collide therewith, and the light emitting property of the phosphor hardly goes on deterioration. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention includes a fluorescent display that includes an anode having a phosphor layer and a cathode that emits electrons in a container portion in a high-vacuum atmosphere, emits electrons from the cathode, and strikes the phosphor layer to emit light. The present invention relates to a device and a method for manufacturing the same, and more particularly, to a fluorescent display device and a method for manufacturing the same, in which the emission of gas in the container portion is small and the deterioration of the light emission characteristics is small and the phosphor layer is hardly peeled off from the anode.

  An anode having a phosphor layer and a cathode that emits electrons are provided inside a container portion that is maintained in a high vacuum atmosphere. Electrons are emitted from the cathode and projected onto the phosphor layer, and display is performed by light emission. Fluorescent display devices that perform are known. Known fluorescent display devices having such a basic structure include a type that emits thermoelectrons using a filament as a cathode and a type that includes a cold cathode that emits electrons by field emission. Further, some of the cold cathodes are known to have a Spindt type electron-emitting device and those having an electron-emitting device using carbon nanotubes.

  As a method for forming the phosphor layer in the manufacture of the fluorescent display device described above, a paste (phosphor paste) containing phosphor particles having a particle size of about 3 to 10 μm is prepared, and this is applied to the anode by a printing method or the like. A method is known in which a desired pattern is deposited and fired to form a phosphor layer.

The inventors of the present invention add a metal oxide such as In ₂ O ₃ or SiO ₂ to a phosphor powder such as ZnO: Zn as a material for manufacturing a phosphor layer of a fluorescent display device, and further for printing A phosphor paste to which a vehicle is added (hereinafter referred to as “conventional phosphor paste”) is manufactured and used to manufacture a type of fluorescent display device using a filament as an electron source.

FIG. 3 is a cross-sectional view of a fluorescent display device in which a phosphor layer is formed using the above-described conventional phosphor paste. This fluorescent display device is a type including an electron-emitting device using carbon nanotubes (this fluorescent display device is referred to as “conventional fluorescent display device”). The container unit 1 of the fluorescent display device 10 is a thin panel-like member in which an anode substrate 2 and a cathode substrate 3 are arranged in parallel with each other at a predetermined interval and the periphery thereof is sealed with a sealing material (not shown). An SiO ₂ layer 4 is formed on the inner surface of the anode substrate 2, and an anode conductor 5 and wirings connected to the anode conductor 5 are formed of aluminum. The wiring of the anode conductor 5 is covered with a crossover 6 which is a low activity lead glass fired at a high temperature. A phosphor layer 17 is formed on the upper surface of the anode conductor 5 by applying the phosphor paste of the conventional example and baking it, and therefore, between the phosphor particles 17 a constituting the phosphor layer 17. Contains metal oxide particles 17b such as In ₂ O ₃ or SiO ₂ dispersed therein. A translucent cathode conductor 8 is formed on the inner surface of the cathode substrate 3, and carbon nanotubes 9 are provided on the surface to form a field emission type electron-emitting device. Here, if an appropriate potential difference is applied between the anode conductor 5 and the cathode conductor 8, electrons are emitted from the carbon nanotubes 9, and this strikes the phosphor layer 17 of the anode conductor 5 to cause the phosphor to emit light. The luminescent display is observed through the cathode substrate 3.

  In addition, as a prior art document related to the technology described above, Patent Document 1 below discloses an example of a structure of a fluorescent display device in which a phosphor layer is formed on an anode made of aluminum. Document 2 discloses a fluorescent display device in which the temperature characteristics of a phosphor are improved by mixing a specific metal oxide into the phosphor and firing it in forming the phosphor layer.

Japanese Patent Laid-Open No. 63-212992 JP-A-1-182390

  According to the study by the inventors of the present application, in the fluorescent display device manufactured using the phosphor paste of the conventional example, gas is generated in the container part for some reason, which may reduce the light emission characteristics of the phosphor layer. I know that there is. In particular, in a cold cathode type fluorescent display device in which the inner volume of the container portion is small and the conductance when the inside of the container portion is exhausted in the manufacturing process is small, the influence of the gas generated in the container portion is large. For example, in a fluorescent display device 10 (carbon nanotube field emission display) having an electron-emitting device using carbon nanotubes as shown in FIG. 3, when a gas is generated in the container 1, the carbon nanotubes 9 that are cold cathodes are gas. As a result, the light emission characteristics deteriorate in a relatively short time, and sufficient luminance cannot be obtained. A similar problem occurs in a fluorescent display device including a Spindt type electron-emitting device.

As a result of research, the inventors of the present application have thought that the cause of such gas generation is the substance added to the phosphor. As a result of diligent efforts toward the development of a phosphor paste suitable for a cold cathode type fluorescent display device, which has no problem of gas generation and the inner volume of the container is small, an improved phosphor paste was obtained. (Hereafter, this is called “phosphor paste of comparative example”, and using this, the fluorescent display device is called “fluorescent display device of comparative example”). The phosphor paste of this comparative example has a composition in which ethyl cellulose is simply added as a printing vehicle to a phosphor powder such as ZnO: Zn without adding a metal oxide such as In ₂ O ₃ or SiO _2. Body paste.

FIG. 4 is a cross-sectional view of the fluorescent display device 20 of the comparative example. This fluorescent display device 20 is a type including an electron-emitting device using carbon nanotubes 9, and the structure is the same as that of the conventional fluorescent display device shown in FIG. 3 except for the phosphor layer. Are denoted by the same reference numerals as those in FIG. However, unlike the fluorescent display device 10 of the conventional example, the fluorescent display device 20 of the comparative example does not include a metal oxide such as In ₂ O ₃ or SiO _{2 in} the phosphor layer 27.

  According to the phosphor paste of this comparative example, no gas is generated in the container portion of the fluorescent display device, and in particular, the phosphor paste of the cold cathode type comparative example 20 having a small inner volume of the container portion 1 is used. However, it was confirmed that there was no problem with the light emission characteristics, but the adhesion of the phosphor layer 27 to the anode conductor 5 was not sufficient, and the phosphor layer 27 was peeled off from the anode conductor 5 during use, and the light emitting display was achieved. It turns out that there is another fatal problem that makes it impossible.

  The present invention has been made on the basis of the new knowledge of the inventors of the present application in order to solve the problems discovered by the inventors of the present invention in the prior art and improved techniques thereof. Provides a fluorescent display device that is less likely to be peeled off from the anode because the phosphor layer hardly adheres to the anode and the phosphor layer is securely attached to the anode. The purpose is to do.

The fluorescent display device according to claim 1 includes a container part whose inside is a high vacuum atmosphere, an anode formed on an inner surface of the container part, a phosphor layer provided on the anode, and an inside of the container part In a fluorescent display device comprising: a cathode that emits electrons; and a phosphor layer that emits electrons by projecting electrons emitted from the cathode to the phosphor layer;
Adhesive particles having a particle size smaller than the particle size of the phosphor constituting the phosphor layer and having an adhesion function for adhering the phosphor to the anode are not included in the phosphor layer. It is characterized by being provided between the phosphor layer and the anode.

The fluorescent display device according to claim 2 is the fluorescent display device according to claim 1,
The adhesive particles are at least one type of adhesive particles selected from an adhesive particle group composed of ultrafine silica, ultrafine lead glass, and ultrafine alumina.

The fluorescent display device according to claim 3 is the fluorescent display device according to claim 1,
The adhesive particles are characterized in that the phosphor layer and the anode are bonded by physical adsorption or chemical adsorption.

The fluorescent display device according to claim 4 is the fluorescent display device according to claim 1,
The fluorescent display device is a carbon nanotube field emission display.

The manufacturing method of the fluorescent display device described in claim 5 is:
In the manufacturing method of the fluorescent display device for performing the light emission display by projecting electrons to the phosphor layer of the anode inside the container part in which the inside is in a high vacuum state,
Forming an anode on the inner surface of the substrate constituting the container portion;
The first paste containing adhesive particles having a particle size smaller than the phosphor constituting the phosphor layer and having an adhesion function for adhering the phosphor to the anode is applied to the surface of the anode and dried,
A second paste containing the phosphor without the adhesive particles is applied onto the dried first paste,
The substrate is fired.

  According to the fluorescent display device of the first aspect, since the adhesive particles securely adhere the phosphor and the anode, the phosphor layer is not peeled off from the anode during use. In addition, since the adhesive particles are not included in the phosphor layer, there is no inconvenience that electrons that hit the phosphor layer during use hit the adhesive particles and generate gas. There is no deterioration of the light emission characteristics due to the gas.

  According to the fluorescent display device described in claim 2, the effect of the fluorescent display device according to claim 1 can be achieved by any of ultrafine silica, ultrafine lead glass, and ultrafine alumina as adhesive particles. .

  According to the fluorescent display device described in claim 3, the effect of the fluorescent display device according to claim 1 is obtained by the fact that adhesive particles are physically adsorbed on the phosphor layer and the anode by intermolecular force, or the phosphor layer is baked. This can be achieved by chemically adsorbing the adhesive particles whose composition has changed on the phosphor layer and the anode.

  The fluorescent display device according to claim 4 is a carbon nanotube field emission display having a small inner volume of the container portion and a small conductance when the inside of the container portion is exhausted in the manufacturing process. The structure of the fluorescent display device according to claim 1, which is free from a substance that causes gas generation due to the projection, is particularly effective for preventing deterioration of light emission characteristics.

  According to the method for manufacturing a fluorescent display device according to claim 5, the adhesive particles are interposed between the anode and the phosphor layer so that the phosphor layer is securely bonded to the anode, and the phosphor layer is bonded. A fluorescent display device containing no particles can be manufactured. Therefore, the phosphor layer is not peeled off from the anode during use of the fluorescent display device, and adhesive particles are not included in the phosphor layer. The disadvantageous phenomenon of generating gas upon hitting the adhesive particles does not occur, and the emission characteristics are not deteriorated by such gas.

(A) is sectional drawing of the fluorescence display apparatus which concerns on embodiment of this invention, (b) is an expanded sectional view of the fluorescent substance layer vicinity in (a). It is the figure which showed the relationship between usage time and an emission residual rate about the fluorescence display apparatus of embodiment, the fluorescence display apparatus of a prior art example, and the fluorescence display apparatus of a comparative example. It is sectional drawing of the fluorescent display apparatus of the prior art example manufactured using the fluorescent substance paste of the prior art example which the present inventors devised. It is sectional drawing of the fluorescent display apparatus of the comparative example manufactured using the fluorescent substance paste of the comparative example which this inventor devised.

FIG. 1 is a cross-sectional view of a fluorescent display device 11 according to the first embodiment of the present invention. First, the structure of the fluorescent display device 11 according to the first embodiment will be described with reference to FIG.
This fluorescent display device 11 is a type equipped with an electron-emitting device using carbon nanotubes 9. The container portion 1 of the fluorescent display device 11 is a thin panel-like member in which an anode substrate 2 and a cathode substrate 3 are arranged in parallel with each other at a predetermined interval and the periphery thereof is sealed with a sealing material (not shown).

An SiO ₂ layer 4 is formed on the inner surface of the anode substrate 2, and an anode conductor 5 and wirings connected to the anode conductor 5 are formed of aluminum. The wiring of the anode conductor 5 is covered with a crossover 6 which is a low activity lead glass fired at a high temperature. When the space between adjacent wires and normal wires is covered with normal lead glass, lead trees that lead to a tree-like lead in the lead glass and make the wires and wires conductive may occur. This crossover 6 prevents such a phenomenon. Although not shown in the figure, when the wiring is in contact with the lead glass for sealing at the seal portion of the container portion 1, so-called seal erosion that is oxidized and breaks may occur. However, this crossover 6 also prevents such a phenomenon.

  On the upper surface of the anode conductor 5, adhesive particles 12 that are functional materials for bonding the anode conductor 5 and a phosphor layer 7 described later are provided. As shown in FIG. 1B in which the portion of the phosphor layer 7 in FIG. 1A is enlarged, the adhesive particles 12 are anodes so as to form partial irregularities on the surface of the flat anode conductor 5. By arranging dots on a part of the upper surface of the conductor 5, the phosphor layer 7 is attached to the anode conductor 5 with high strength without hindering electrical conduction between the phosphor layer 7 and the anode conductor 5. Yes. The adhesive particles 12 are chemically adsorbed to the phosphor layer 7 and the anode conductor 5 because the particle size is at least smaller than the particle size of the phosphor of the phosphor layer 7 and the composition changes at the firing temperature of the phosphor layer 7. Thus, it is necessary to have a function of adhering them together or by physically adsorbing them to the phosphor layer 7 and the anode conductor 5 by an intermolecular force.

In this example, ultrafine silica (SiO ₂ ) is used as the adhesive particles 12. This is an ultrafine dry silica known as Aerosil (registered trademark), for example, fumed obtained by synthesizing silica fine particles by vaporizing silicon chloride and causing a gas phase reaction in a high-temperature hydrogen flame. It is a kind of silica. This substance consists of primary particles that are amorphous glassy and have no spherical pores, but are produced as aggregated particles or clusters of several molecules having a three-dimensional structure strongly bound in the manufacturing process. Compared to wet silica, the specific surface area relative to the particle size is small because there are no pores. Moreover, even if it is a dry-type silica, it is different from the fused silica particle produced | generated from a molten state. As a commercially available product, a hydrophilic product having a primary particle size of about 7 nm to 40 nm is known. As described above, the particle size of the adhesive particle 12 suitably used in the first embodiment is a phosphor. It is smaller than the particle size of the phosphor of the layer 7, for example, about 8 nm (0.008 μm). Ultra fine powder dry silica is a bulky powder having a volume of about 2 liters at 100 g. Since the ultra fine powder dry silica has siloxane and silanol groups on its surface, for example, the ultra fine powder dry silica is applied to the surface of the anode conductor 5 and further ZnO: Zn as in the first embodiment. When the phosphor is applied and baked at about 500 ° C., O is removed from the phosphor and the composition changes from SiOH to SiO _2. Therefore, the phosphor layer 7 and the anode conductor are bonded with strong adhesion due to chemical adsorption caused by the composition change. 5 is adhered. In the present embodiment, the mode or cause of the adhesion between the phosphor layer 7 and the anode conductor 5 through the ultrafine powder dry silica as the adhesive particles 12 is not only the above-described chemical adsorption but also physical adsorption by intermolecular force. It is thought that there is also.

On the adhesive particle 12 layer, a phosphor layer 7 made of ZnO: Zn phosphor is formed by depositing and baking a phosphor paste. In this example, the ZnO: Zn phosphor particles constituting the phosphor layer 7 do not contain any In ₂ O ₃ or SiO ₂ . Therefore, no gas is generated even if electrons hit the phosphor during use.

  A translucent cathode conductor 8 is formed on the inner surface of the cathode substrate 3, and carbon nanotubes 9 are provided on the surface to form a field emission type electron-emitting device.

  In the above configuration, when an appropriate potential difference is applied between the anode conductor 5 and the cathode conductor 8, electrons are emitted from the carbon nanotubes 9 and project into the phosphor layer 7 of the anode conductor 5 to emit the phosphor. The light-emitting display can be observed from the outside of the container part 1 through the cathode substrate 3.

Next, a method for manufacturing the fluorescent display device 11 according to the first embodiment will be described.
The above-mentioned adhesive particles 12 of ultrafine silica 10 wt% and terpineol 90 wt% are mixed and subjected to ultrasonic dispersion by an ultrasonic dispersing device to produce a transparent ultrafine silica vehicle.

  2 wt% of the ultra fine silica vehicle described above and 98 wt% of a vehicle that is a mixture of ethyl cellulose and terpineol are mixed to obtain an undercoat paste that is the first paste. This undercoat paste contains 0.2 wt% of ultrafine silica.

On the other hand, a SiO ₂ film 4 having a thickness of about 0.1 μm is formed on the inner surface of the anode substrate 2 constituting a part of the container portion 1 of the fluorescent display device 11, and an aluminum having a thickness of about 1 μm is formed thereon. Thus, the anode conductor 5 and the wiring are formed in a desired pattern. A crossover 6 is deposited and fired at a necessary portion of the wiring.

An undercoat paste is applied so as to cover the anode conductor 5 and dried. In a state where terpineol is evaporated by evaporation and ethyl cellulose and ultrafine silica remain, the thickness is about 0.1 μm. On this undercoat paste, the phosphor paste of the comparative example as the second paste is applied to a thickness of about 20 μm. As described above, the phosphor paste of the comparative example is a paste having a composition in which ethyl cellulose is added to a phosphor powder such as ZnO: Zn without adding a metal oxide such as In ₂ O ₃ or SiO _2. is there.

The anode substrate 2 is fired at a temperature of about 500 ° C. By firing, the undercoat paste decomposes into ethyl cellulose, leaving only ultrafine silica having a particle size of, for example, about 0.008 μm, and the upper surface of the anode conductor 5 without disturbing the electrical conduction between the phosphor layer 7 and the anode conductor 5. As a result, the phosphor particles 7 are adhered to the anode conductor 5 with high strength. A phosphor layer 7 having a thickness of about 15 μm is formed on the adhesive layer. In this firing step, the silanol group of the ultrafine powder dry silica takes O from the phosphor and changes its composition from SiOH to SiO ₂ , so that the phosphor layer 7 and the anode conductor 5 are bonded with strong adhesion.

Next, the effect by 1st Embodiment is demonstrated compared with a prior art example and a comparative example.
As shown in FIG. 2, according to the fluorescent display device 11 of the first embodiment (see the graph of “embodiment” connecting points indicated by ○ in FIG. 2), the lighting time (horizontal axis: time [h] ), The emission remaining rate (vertical axis: [%]) gradually decreases from the initial 100%, but there is an emission remaining rate of nearly 70% even after 500 hours. Moreover, there is no problem that the phosphor layer 7 is peeled off from the anode conductor 5 during use.

  On the other hand, in the fluorescent display device 10 of the conventional example (see the graph connecting points indicated by □ in FIG. 2), the emission reduction considered to be caused by gas emission from the metal oxide 17b in the phosphor layer 17 is reduced. The emission residual rate is 40% or less after 500 hours, and the practically required performance is not satisfied.

  In addition, in the fluorescent display device 20 of the comparative example (see the graph connecting the points indicated by x in FIG. 2), the reduction rate of the emission remaining rate is almost the same as that of the first embodiment, which is good, but as described above. In addition, there is a problem that the phosphor layer 27 is easily peeled off from the anode conductor 5 during use, and cannot be practically used.

  As described above, according to the fluorescent display device 11 of the first embodiment, the ultra fine powder dry silica reliably bonds and fixes the phosphor and the anode conductor 5 by physical adsorption by intermolecular force or chemical adsorption by composition change. The phosphor layer 7 is not peeled off from the anode conductor 5 during use, and the phosphor layer 7 contains no foreign matter that emits gas during use. There is no risk of deterioration.

In particular, in the fluorescent display device 11 of the first embodiment, the distance between the anode substrate 2 and the cathode substrate 3 is about 30 μm, for example, and the inner volume of the container part 1 is small, and the container part 1 is evacuated in the manufacturing process. Since this is a carbon nanotube field emission display with a low conductance, the structure as in this example in which no substance causing gas generation due to electron beam projection is present in the phosphor layer 7, the phosphor layer 7 emits light. This is particularly effective in order not to deteriorate the characteristics.

Next, a fluorescent display device according to another embodiment of the present invention will be described.
In the first embodiment, ultrafine silica (SiO ₂ ) is used as the adhesive particles 12, but instead of this, ultrafine lead glass or ultrafine alumina can be used. Even when ultrafine lead glass or ultrafine alumina is used, the particle size must be smaller than that of the phosphor. In addition, the manufacturing method of the undercoat paste including this and the materials used for the vehicle are the same as those in the first embodiment. However, when ultrafine powdered lead glass is used, the function of adhering the phosphor layer 7 and the anode conductor 5 is that the contact area is increased by melting the finely divided powdered lead glass, thereby causing physical adsorption by intermolecular force. When ultra-fine powder alumina is used, the function of adhering the phosphor layer 7 and the anode conductor 5 is the same as that in the first embodiment due to the intermolecular force. Chemisorption by adsorption or composition change. The adhesive particles are not limited to one type, and a plurality of types of adhesive particles may be mixed and used. For example, two or more types of ultrafine powder adhesive particles arbitrarily selected from ultrafine silica (SiO ₂ ), ultrafine lead glass, and ultrafine alumina may be mixed and used at an appropriate ratio.

DESCRIPTION OF SYMBOLS 1 ... Container part 2 ... Anode substrate 3 ... Cathode substrate 5 ... Anode conductor 7 ... Phosphor layer 8 ... Cathode conductor 9 ... Carbon nanotube 10 ... Conventional fluorescent display device 11 ... Embodiment fluorescent display device 12 ... Adhesive particle 20 ... Comparative Example Fluorescent Display Device

Claims (5)

A container part having an internal high vacuum atmosphere; an anode formed on an inner surface of the container part; a phosphor layer provided on the anode; and a cathode provided in the container part to emit electrons. In the fluorescent display device for causing the phosphor layer to emit light by projecting electrons emitted from the cathode to the phosphor layer,
Adhesive particles having a particle size smaller than the particle size of the phosphor constituting the phosphor layer and having an adhesion function for adhering the phosphor to the anode are not included in the phosphor layer. The fluorescent display device is provided between the phosphor layer and the anode. 2. The fluorescent display according to claim 1, wherein the adhesive particles are at least one type of adhesive particles selected from an adhesive particle group composed of ultrafine silica, ultrafine lead glass, and ultrafine alumina. apparatus. 2. The fluorescent display device according to claim 1, wherein the adhesive particles adhere the phosphor layer and the anode by physical adsorption or chemical adsorption. The fluorescent display device according to claim 1, wherein the fluorescent display device is a carbon nanotube field emission display. In the manufacturing method of the fluorescent display device for performing the light emission display by projecting electrons to the phosphor layer of the anode inside the container part in which the inside is in a high vacuum state,
Forming an anode on the inner surface of the substrate constituting the container portion;
The first paste containing adhesive particles having a particle size smaller than the phosphor constituting the phosphor layer and having an adhesion function for adhering the phosphor to the anode is applied to the surface of the anode and dried,
A second paste containing the phosphor without the adhesive particles is applied onto the dried first paste,
A method of manufacturing a fluorescent display device, comprising firing the substrate.

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