JP2004095267A - Fluorescent screen with metal back and its forming method as well as image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate projections and depressions on a metal back layer and improve its pressure-resistant property on a fluorescent screen with a metal back of an image display device such as an FED (field emission display). <P>SOLUTION: This fluorescent screen with the metal back has a black matrix and a phosphor layer on a face plate inside surface, has the metal back layer on the phosphor layer, and is characterized by having a light absorbing layer in two or more layers on which the black matrix are laminated. A second light-absorbing layer with a thickness of 5 μm or more formed by a printing method can be placed on an upper layer of a first light absorbing layer with a thickness of 5 μm or less formed by a photolithography method. The second light absorbing layer, then, can be configured to be smaller in the formed area than the first light absorbing layer. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a phosphor screen with a metal back, a method for forming a phosphor screen with a metal back, and a flat-panel image display device having a phosphor screen with a metal back.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image display device such as a cathode ray tube (CRT) or a field emission display (FED), a metal back in which a metal film such as an aluminum (Al) film is formed on an inner surface (a surface on an electron source side) of a phosphor layer. The fluorescent screen of the system is widely adopted.
[0003]
The metal film on the phosphor screen is called a metal back layer. Of the light emitted from the phosphor by the electrons emitted from the electron source, the light traveling toward the electron source is reflected in the direction of the face plate and the luminance is reduced. And imparts conductivity to the phosphor screen to serve as an anode electrode. Further, it has a function of preventing the phosphor from being damaged by ions generated by ionization of the gas remaining in the vacuum envelope.
[0004]
Usually, the metal back layer is formed by forming a thin film made of an organic resin such as nitrocellulose on the phosphor layer by a spin method or the like, and then vacuum-depositing Al thereon, and further baking to remove organic substances. Is done by the method.
[0005]
[Problems to be solved by the invention]
However, in the conventional phosphor screen with a metal back, the flatness of the phosphor screen is poor such as a step (unevenness) between the upper surface of the phosphor layer and the upper surface of the black matrix. The layer was poor in film-forming properties, and irregularities, wrinkles, cracks, and the like were easily generated.
[0006]
In the FED, a gap (interval) between a face plate having a fluorescent screen and a rear plate having an electron-emitting device is extremely narrow, about 1 mm to several mm, and a high voltage of about 10 kV is applied to this narrow interval. Since a strong electric field is formed, if the metal back layer has irregularities, the electric field concentrates on a slight protrusion, and there is a possibility that a discharge (vacuum arc discharge) is generated therefrom. When such an abnormal discharge occurs, a large discharge current ranging from several A to several hundred A flows instantaneously, so that the electron-emitting device in the cathode portion and the fluorescent screen in the anode portion may be broken or damaged. .
[0007]
For this reason, the metal back layer must be formed so as not to form irregularities on the surface, and it is difficult to set the conditions for forming the metal back layer, resulting in a decrease in productivity.
[0008]
In a flat-panel image display device such as an FED, in assembling the face plate and the rear plate, the pattern of the phosphor layer and the position of the corresponding electron emission source are adjusted to be within 10 μm over the entire screen. It was necessary to match with high precision. If the accuracy of the alignment between the phosphor layer pattern and the electron emission source is poor, not only the time required for production becomes longer, but also the product becomes defective, resulting in a problem that the production efficiency is reduced. In addition, there is a problem that the display quality is lowered, for example, the color purity of the entire screen is lowered.
[0009]
The present invention has been made in order to solve these problems, and the surface of the metal back layer is smooth, the occurrence of abnormal discharge is suppressed, and an image capable of high-quality display with high production efficiency and high color purity is provided. It is an object to provide a display device.
[0010]
[Means for Solving the Problems]
The phosphor screen with a metal back according to the present invention is a phosphor screen having at least a black matrix and a phosphor layer on the inner surface of a face plate, and having a metal back layer on them, wherein the black matrix is a two-layer It is characterized by having the above light absorbing layer.
[0011]
In the metal-backed phosphor screen of the present invention, the black matrix may have a first light absorbing layer formed by a photolithographic method and a second light absorbing layer formed thereon by a printing method. The first light absorbing layer has a layer thickness of 5 μm or less, and the second light absorbing layer has a layer thickness of 5 μm or more and has a larger formation area than the first light absorbing layer. Can be configured to be small.
[0012]
In the phosphor screen with a metal back of the present invention, an adhesive layer containing a heat-resistant inorganic oxide as a main component can be provided between the first light absorbing layer and the second light absorbing layer.
[0013]
The method of forming a phosphor screen with a metal back according to the present invention includes the steps of: forming a black matrix on the inner surface of the face plate; forming a phosphor layer at a predetermined position on the inner surface of the face plate; Forming a metal back layer on the phosphor layer, wherein the step of forming the black matrix includes the step of forming a lower layer for forming a first light absorbing layer by a photolithographic method, and the step of forming the first light absorbing layer. And forming an upper layer by printing a second light absorbing layer on the upper layer.
[0014]
In the method for forming a phosphor screen with a metal back according to the present invention, an adhesive layer mainly composed of a heat-resistant inorganic oxide is provided between the first light absorbing layer and the second light absorbing layer between the lower layer forming step and the upper layer forming step. The method may include a bonding layer forming step of forming the bonding layer so as to be sandwiched between the light absorbing layer and the light absorbing layer.
[0015]
An image display device according to the present invention includes a face plate, a rear plate opposed to the face plate, a number of electron-emitting devices formed on the rear plate, and the electron-emitting device formed on the face plate. A phosphor screen having a phosphor layer that emits light by an electron beam emitted from the element is provided, and the phosphor screen is the above-described phosphor screen with a metal back.
[0016]
In the phosphor screen with metal back and the image display device of the present invention, since the black matrix has a structure in which two or more light absorbing layers are laminated, a step is not generated between the phosphor matrix and the phosphor layer. And the total thickness of the black matrix can be adjusted. Therefore, there is no step or unevenness on the phosphor screen, and sufficient flatness is realized, so that the film forming property of the metal back layer formed on the phosphor screen is improved, and a smooth metal back layer without irregularities and wrinkles is formed. And the withstand voltage characteristics are greatly improved.
[0017]
Further, by forming the lower first light absorbing layer by the photolithography method and forming the upper second light absorbing layer by the printing method, the position of the pattern of the phosphor layer and the corresponding electron emission source can be improved. The accuracy is improved. Therefore, manufacturing efficiency and yield are improved. In addition, high-quality display with high color purity is possible.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0019]
FIG. 1 is a sectional view showing a first embodiment of a phosphor screen with a metal back according to the present invention.
[0020]
In FIG. 1, reference numeral 1 denotes a glass substrate (panel), and a black matrix 2 having a predetermined pattern (for example, a stripe shape or a dot shape) is provided on an inner surface of the glass substrate 1. The black matrix 2 has a structure in which a first light absorbing layer 2a and a second light absorbing layer 2b are stacked. The first light absorbing layer 2a has a layer thickness of 5 μm or less and is formed by a photolithographic method.
[0021]
In order to form the first light absorbing layer 2a by a photolithographic method, a photoresist is applied to the inner surface of a glass substrate, exposed through a mask having a predetermined pattern, and developed to form a resist pattern. Then, an aqueous solution containing a light-absorbing substance such as graphite is applied and bound thereon, and then the resist and the layer of the light-absorbing substance thereon are dissolved and dissolved by a decomposing agent composed of 10% by weight (wt%) of sulfamic acid. A method of peeling is adopted.
[0022]
On the first light absorbing layer 2a formed by such a photolithography method, a second light absorbing layer 2b mainly composed of graphite or the like is formed by a printing method such as screen printing. I have. The second light absorbing layer 2b has a layer thickness of 5 μm or more, and has a smaller pattern formation area than the first light absorbing layer 2a.
[0023]
A phosphor layer 3 of three colors of red (R), green (G), and blue (B) is formed between the patterns of the black matrix 2 by a photolithography method (slurry method) using a phosphor slurry, a printing method. And the like. Further, a metal back layer 4 made of a metal film such as Al is formed on a phosphor screen composed of the black matrix 2 and the phosphor layer 3 of each color.
[0024]
For example, in order to form the phosphor layers 3 of each color by the slurry method, a blue phosphor slurry is applied on the black matrix 2 and dried to form a coating film of the blue phosphor on the entire inner surface of the glass substrate 1. Thereafter, exposure and development are performed through a mask, and the uncured portion is washed away to form a blue phosphor layer at a predetermined position. Next, similarly, a green phosphor layer and a red phosphor layer are sequentially formed. Here, as the blue phosphor slurry, one containing a blue phosphor (ZnS: Δg, Al), PVA (polyvinyl alcohol), and dichromate as main components and a surfactant added thereto is used. As the green phosphor slurry, a green phosphor (ZnS: Cu, Δl), which is mainly composed of PVA and dichromate, and to which a surfactant is added, is used. a red phosphor _{(Y 2 O 2 S: Eu} ) and mainly composed of PVA and dichromate can be used those obtained by adding a surfactant thereto.
[0025]
In order to form the metal back layer 4 on the phosphor screen, for example, a metal film such as Al is vacuum-deposited on a thin film made of an organic resin such as nitrocellulose formed by a spin method, and further, about 450 ° C. To remove organic substances by baking at the above temperature. Further, as shown below, the metal back layer 4 can be formed using a transfer film.
[0026]
The transfer film has a structure in which a metal film such as Al and an adhesive layer are sequentially laminated on a base film via a release agent layer (a protective film if necessary). The agent layer is disposed so as to be in contact with the phosphor layer, and a pressing process is performed. The pressing method includes a stamp method, a roller method, and the like. By pressing the transfer film and bonding the metal film in this manner, the base film is peeled off, whereby the metal film is transferred to the phosphor screen. Next, heat treatment (baking) is performed to decompose and remove organic components, thereby forming a metal back layer.
[0027]
In the first embodiment configured as described above, the black matrix 2 is formed by laminating a first light absorbing layer 2a formed by a photolithographic method and a second light absorbing layer 2b formed by a printing method. The black matrix 2 and the phosphor layer 3 have the same thickness, thereby eliminating the steps and unevenness of the phosphor screen, and forming a smooth metal back layer without unevenness on the surface. Can be.
[0028]
Further, the pattern of the phosphor layer 3 can be formed with high positional accuracy. That is, the first light absorbing layer 2a formed by the photolithographic method is thin, having a thickness of 5 μm or less, but is formed between the patterns of the first light absorbing layer 2a because of its high positional accuracy. The position accuracy of the phosphor layer 3 also increases. Therefore, the alignment between the pattern of the phosphor layer 3 and the corresponding electron emission source is improved, and high-quality display with high color purity is possible. On the other hand, since the second light absorbing layer 2b is formed by a printing method, the positional accuracy is not sufficient, but the thickness can be easily adjusted, and the layer having a thickness of 5 μm or more can be formed by one coating. Can be formed. Therefore, by laminating the second light absorbing layer 2b formed by the printing method on the first light absorbing layer 2a, the entire black matrix 2 is formed so that no step is formed between the second light absorbing layer 2b and the phosphor layer 3. Can be easily adjusted, and a smooth fluorescent screen without unevenness can be formed.
[0029]
Since the area of the pattern of the second light absorbing layer 2b formed by the printing method is smaller than that of the first light absorbing layer 2a, the positional accuracy of the second light absorbing layer 2b is not sufficient. However, the position accuracy of the black matrix 2 as a whole is determined by that of the lower first light absorption layer 2a, and has sufficiently high position accuracy.
[0030]
Next, a second embodiment of the metal-backed phosphor screen will be described.
[0031]
In the second embodiment, as shown in FIG. 2, an adhesive layer 5 mainly composed of a heat-resistant inorganic oxide is provided between the first light absorbing layer 2a and the second light absorbing layer 2b. Is formed. Note that the other parts are configured in the same manner as in the first embodiment, and a description thereof will be omitted.
[0032]
The kind of the heat-resistant inorganic fine particles is not particularly limited, and is at least selected from metal or nonmetal oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ , MnO ₂ , SnO ₂ , ZrO ₂ , and ITO. One type can be used. Such an adhesive layer 5 containing a heat-resistant inorganic oxide as a main component can be formed by a method such as screen printing or spray coating.
[0033]
For example, in order to form the adhesive layer 5 containing silica (SiO ₂ ) as a main component, a paste in which silica is mixed with a dispersant, a resin binder, a solvent, and the like is applied by screen printing or the like, and heated and baked at 450 ° C. for 30 minutes. And the like. In this embodiment, the adhesive layer 5 is continuously provided not only on the first light absorbing layer 2a (between the second light absorbing layer 2b) but also on the glass substrate 1. Although there is an advantage that the formation is easy, the patterned adhesive layer 5 may be formed only on the first light absorption layer 2a.
[0034]
In the second embodiment, the adhesive layer 5 mainly composed of a heat-resistant inorganic oxide is formed between the first light absorbing layer 2a and the second light absorbing layer 2b. The adhesive strength between the first light absorbing layer 2a and the second light absorbing layer 2b is improved. As a result, the positional accuracy of the second light absorbing layer 2b and the phosphor layer 3 formed thereon is further improved, and high-quality display with high color purity is possible.
[0035]
Next, as a third embodiment of the present invention, an FED using a phosphor screen with a metal back as an anode electrode is shown in FIG.
[0036]
In the FED, the face plate 6 having the phosphor screen with the metal back according to the first embodiment and the rear plate 8 having the electron-emitting devices 7 arranged in a matrix form have a narrow gap of about 1 mm to several mm. And a high voltage of 5 to 15 kV is applied between the face plate 6 and the rear plate 8. In the drawing, reference numeral 9 denotes a phosphor screen having the above-described two-layer structure black matrix and phosphor layer, and reference numeral 10 denotes a metal back layer. Reference numeral 11 denotes a support frame (side wall).
[0037]
Although the gap between the face plate 6 and the rear plate 8 is extremely small and discharge (dielectric breakdown) easily occurs between them, this FED has a smooth and flat metal back layer 10 with no unevenness or wrinkles on the surface. As a result, the occurrence of abnormal discharge is suppressed, and the withstand voltage characteristics are greatly improved.
[0038]
In addition, since the positional accuracy between the pattern of the phosphor layer and the corresponding electron-emitting device is good, high-quality display is possible with high color purity, and the manufacturing efficiency is good and the yield is high.
[0039]
Next, a specific example in which the present invention is applied to an FED will be described.
[0040]
EXAMPLE A first light absorbing layer (1 μm thick) made of graphite was formed in a stripe shape on a glass substrate by a photolithographic method. The width of the stripe was 80 μm and the interval was 200 μm.
[0041]
Next, a paste having the following composition containing silica (SiO ₂ ) as a main component is applied by a spray method on the entire surface of the glass substrate on which the first light absorption layer is formed, and then heated and baked at 450 ° C. for 30 minutes. An adhesive layer made of silica was formed.
[0042]
Composition of silica paste SiO ₂ 30 wt%
Dispersant ………… 5wt%
Binder resin (ethyl cellulose) 6 wt%
Solvent (butyl carbitol acetate) ... 59 wt%
[0043]
Next, a second light-absorbing layer (9 μm in thickness) containing graphite as a main component was formed on the silica layer by screen printing. The second light absorbing layer has a stripe-shaped pattern having a width of 65 μm and an interval of 200 μm, and is formed such that each stripe is located above the corresponding stripe of the first light absorbing layer. ing.
[0044]
Next, phosphor layers (thickness: 10 μm) of three colors of red (R), green (G), and blue (B) were formed between the patterns of the second light absorption layer by a printing method. In order to form a phosphor layer of each color, phosphor paste of each color having the following composition was screen-printed, dried at 90 ° C. for 10 minutes, and then heated at 450 ° C. for 2 hours and fired.
[0045]
Composition of phosphor paste Phosphor 40 wt%
Resin (ethyl cellulose) 6 wt%
Solvent (butyl carbitol acetate) 54% by weight
[0046]
An organic resin solution containing an acrylic resin as a main component was applied on the phosphor screen thus formed, dried to form an organic resin layer, and an Al film was formed thereon by vacuum evaporation. Next, it was heated and baked at a temperature of 450 ° C. for 30 minutes to decompose and remove organic components, thereby forming a metal back layer.
[0047]
As a comparative example, a light absorbing layer having a thickness of 10 μm was formed on a glass substrate by screen printing using a black paste containing graphite as a main component. Then, a phosphor screen with a metal back was produced in the same manner as in Example except that a black matrix was constituted only by this light absorbing layer without forming an adhesive layer.
[0048]
Next, FEDs were manufactured using the panels having the phosphor screens with metal backs obtained in Examples and Comparative Examples. That is, an electron source in which a large number of surface conduction electron-emitting devices are formed in a matrix on a substrate is fixed to a rear glass substrate to form a rear plate, and the rear plate and the glass substrate having the above-described phosphor screen with metal back ( And a face plate) were disposed facing each other with a support frame and a spacer interposed therebetween, and sealed with frit glass. The gap between the face plate and the rear plate was 2 mm. Next, necessary processes such as vacuum evacuation and sealing were performed to complete the FED.
[0049]
The withstand voltage characteristics of the FED thus obtained were measured and evaluated by a conventional method. The position accuracy of the pattern of the phosphor layer was measured using a length measuring machine (Mercury-5000S manufactured by V Technology Co., Ltd.), and the color purity was further evaluated.
[0050]
As a result of the measurement, the FED provided with the metal-backed fluorescent screen obtained in the example had better withstand voltage characteristics than those obtained in the comparative example. In addition, the position accuracy of the phosphor layer pattern was high, the color purity was good, and high quality display was obtained.
[0051]
【The invention's effect】
As described above, according to the present invention, a smooth metal back layer without irregularities or wrinkles can be obtained, and the occurrence of discharge can be suppressed, and a phosphor screen with a metal back having excellent withstand voltage characteristics can be obtained. Therefore, in an image display device having such a phosphor screen, the withstand voltage characteristics are significantly improved. In addition, since the positional accuracy between the pattern of the phosphor layer and the corresponding electron emission source is improved, the efficiency of production and the yield are improved, and high-quality display with high color purity can be realized.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a first embodiment of a phosphor screen with a metal back according to the present invention.
FIG. 2 is a sectional view showing a second embodiment of a metal-backed phosphor screen according to the present invention.
FIG. 3 is a sectional view schematically showing the structure of an FED according to a third embodiment of the present invention.
[Explanation of symbols]
1 ... Glass substrate, 2 ... Black matrix, 2a ... First light absorbing layer, 2b ... Second light absorbing layer, 3 ... Phosphor layer, 4, 10 ... Metal back layer, 5 Adhesive layer, 6 Face plate, 7 Electron-emitting device, 8 Rear plate, 9 Phosphor screen, 11 Support frame

Claims (7)

A phosphor screen having at least a black matrix and a phosphor layer on the inner surface of the face plate, and having a metal back layer thereon.
A phosphor screen with a metal back, wherein the black matrix has two or more light absorbing layers laminated. The fluorescent material with a metal back according to claim 1, wherein the black matrix has a first light absorbing layer formed by a photolithographic method and a second light absorbing layer formed thereon by a printing method. surface. The first light absorption layer has a layer thickness of 5 μm or less, the second light absorption layer has a layer thickness of 5 μm or more, and the formation area is smaller than that of the first light absorption layer. The phosphor screen with a metal back according to claim 2. 4. An adhesive layer comprising a heat-resistant inorganic oxide as a main component, between the first light absorbing layer and the second light absorbing layer. Phosphor screen with metal back. A step of forming a black matrix on the inner surface of the face plate,
Forming a phosphor layer at a predetermined position on the inner surface of the face plate,
Forming a metal back layer on the black matrix and the phosphor layer,
The step of forming the black matrix includes a lower layer forming step of forming a first light absorbing layer by a photolithography method, and an upper layer forming step of forming a second light absorbing layer on the first light absorbing layer by printing. A method for forming a phosphor screen with a metal back, comprising the steps of: Between the lower layer forming step and the upper layer forming step, an adhesive layer containing a heat-resistant inorganic oxide as a main component is sandwiched between the first light absorbing layer and the second light absorbing layer. 6. The method for forming a phosphor screen with a metal back according to claim 5, further comprising a step of forming an adhesive layer. A face plate, a rear plate opposed to the face plate, a large number of electron-emitting devices formed on the rear plate, and an electron beam formed on the face plate and emitted from the electron-emitting device. An image display device comprising a phosphor screen having a phosphor layer that emits light, wherein the phosphor screen is the phosphor screen with a metal back according to any one of claims 1 to 4.

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