JP4050588B2 - Image display device, method for manufacturing the same, and device for manufacturing image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image display device, and more particularly to a flat-type image display device using an electron-emitting device, a method for manufacturing the same, and an apparatus for manufacturing the image display device.
[0002]
[Prior art]
In recent years, as a next-generation image display device, development of a flat-type image display device in which a large number of electron-emitting devices are arranged and opposed to a phosphor screen has been advanced. There are various types of electron-emitting devices, all of which basically use field emission, and display devices using these electron-emitting devices are generally called field emission displays (hereinafter referred to as FED). )is called. Among FEDs, a display device using a surface conduction electron-emitting device is also called a surface conduction electron-emission display (hereinafter referred to as SED). In this application, the term FED is used as a general term including SED. .
[0003]
The FED generally has a front substrate and a rear substrate that are arranged to face each other with a predetermined gap, and these substrates are joined together by connecting peripheral portions to each other through a rectangular frame-shaped side wall. Is configured. The inside of the vacuum vessel is maintained at a high vacuum with a degree of vacuum of about 10 ⁻⁴ Pa or less. Further, in order to support an atmospheric pressure load applied to the rear substrate and the front substrate, a plurality of support members are disposed between these substrates.
[0004]
A phosphor screen including red, blue, and green phosphor layers is formed on the inner surface of the front substrate, and a plurality of electron-emitting devices that emit electrons that excite the phosphor to emit light are provided on the inner surface of the rear substrate. ing. A large number of scanning lines and signal lines are formed in a matrix and connected to each electron-emitting device.
[0005]
An anode voltage is applied to the phosphor screen, and the electron beam emitted from the electron-emitting device is accelerated by the anode voltage and collides with the phosphor screen, whereby the phosphor emits light and an image is displayed.
[0006]
In such an FED, the gap between the front substrate and the rear substrate can be set to several millimeters or less, which is lighter than a cathode ray tube (CRT) currently used as a display of a television or a computer. Thinning can be achieved.
[0007]
In the FED configured as described above, in order to obtain practical display characteristics, a fluorescent material similar to a normal cathode ray tube is used, and a fluorescent material in which an aluminum thin film called a metal back is formed on the fluorescent material. It is necessary to use a surface. In this case, the anode voltage applied to the phosphor screen is desired to be at least several kV, preferably 10 kV or more.
[0008]
However, the gap between the front substrate and the rear substrate cannot be made too large from the viewpoint of resolution, characteristics of the support member, etc., and needs to be set to about 1 to 2 mm. Therefore, in the FED, it is inevitable that a strong electric field is formed in a small gap between the front substrate and the rear substrate, and discharge (dielectric breakdown) between the two substrates becomes a problem.
[0009]
When discharge occurs, a current of 100 A or more may flow instantaneously, which may cause destruction or deterioration of the electron-emitting device and the phosphor screen, and further destruction of the drive circuit. These are collectively referred to as discharge damage. Such a discharge that leads to the occurrence of a defect is not allowed as a product. Therefore, in order to put the FED into practical use, it must be configured so that damage due to discharge does not occur over a long period of time. However, it is very difficult to completely suppress the discharge over a long period of time.
[0010]
Therefore, it is important to take measures to suppress the scale of discharge so that the influence on the electron-emitting device can be ignored even if discharge occurs. As a technique related to such a concept, Patent Document 1 discloses a technique for locally dividing a metal back to form a pattern such as a zigzag, and Patent Document 2 discloses a technique for dividing a metal back into a plurality of regions. Techniques to do this are disclosed.
[0011]
These are inventions related to the concept and do not stipulate a specific method for dividing the metal back, but according to the specification, a method for dividing the metal back with a laser, or masking vapor deposition using a metal mask. A method of forming a pattern is assumed.
[0012]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-311642
[Patent Document 2]
Japanese Patent Laid-Open No. 10-326583
[Problems to be solved by the invention]
However, these methods have problems when considering characteristics and mass productivity.
As for the laser, it takes a long time to scan, the apparatus is expensive, the components of the metal back film and the light shielding layer are scattered and it becomes a defect on the image and the discharged power is removed. There is a problem that it is difficult to sufficiently clean and a minute protrusion or the like may be formed, which may be a limitation in increasing the withstand voltage of the divided portion.
[0015]
As for masking vapor deposition, there is a problem that it becomes difficult to ensure accuracy as the size of the masking vapor deposition increases. Also, since the metal back layer is a weak film, it is desirable that the metal mask is not in contact with the front substrate, but this requires a tough tension application structure. Therefore, practicality is impaired as the size increases.
[0016]
Further, since the vapor deposition method is a vacuum process, there is a disadvantage in terms of mass production, and it is conceivable to use another method such as transfer of a metal thin film sheet. In that case, however, a method such as masking cannot be used.
[0017]
In this way, it is effective to divide the metal back in order to suppress discharge damage, but considering characteristics and mass productivity, there are problems with the laser and masking deposition methods, and there are alternative methods. It was strongly desired.
[0018]
The present invention is for solving such problems, and its purpose is to provide a metal back cutting technique suitable for both characteristics and mass productivity, to sufficiently reduce the scale of discharge, and to emit electrons. An object of the present invention is to provide an image display device capable of preventing destruction and deterioration of elements and phosphor screens and circuit destruction, a method for manufacturing the image display device, and a device for manufacturing the image display device.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, an image display device according to an aspect of the present invention includes a front substrate having a phosphor screen including a phosphor layer and a light shielding layer, and a metal back layer comprising a thin film provided on the phosphor screen. And a rear substrate disposed opposite to the front substrate and having a plurality of electron-emitting devices that emit electrons toward the phosphor screen, and
The metal back layer includes a plurality of oxidized regions anodized in the layer thickness direction from one surface of the metal back layer to the other surface, and a plurality of non-oxidized regions , each having the metal back layer as an anode. It is characterized by having.
[0020]
Moreover, the manufacturing method of the image display apparatus which concerns on the other aspect of this invention had the fluorescent screen containing a fluorescent substance layer and a light shielding layer, and the metal back layer which consists of an electroconductive thin film provided on the said fluorescent screen. In a method for manufacturing an image display device, comprising: a front substrate; and a rear substrate disposed opposite to the front substrate and provided with a plurality of electron-emitting devices that emit electrons toward the phosphor screen. ,
A metal back layer was formed on the phosphor surface of the front substrate, and a plurality of locations of the metal back layer were anodized, and each of the metal back layers was oxidized in the layer thickness direction from one surface to the other surface. A plurality of oxidized regions and a plurality of non-oxidized regions are formed.
[0021]
Furthermore, the manufacturing apparatus of the image display device according to another aspect of the present invention includes a structure in which the electrolytic solution is selectively brought into contact with the oxidized region of the metal back layer, and a cathode that supplies a potential to the electrolytic solution. And a voltage supply unit for applying a voltage between the metal back layer serving as an anode and the cathode.
[0022]
According to the image display device having the above configuration, the metal back layer is electrically divided by the plurality of oxidized regions, and the resistance between the adjacent non- oxidized regions can be set to a high resistance or insulating state. Therefore, the effective impedance of the phosphor screen can be increased, and the discharge current can be sufficiently reduced even when a discharge occurs between the front substrate and the rear substrate.
[0023]
Moreover, according to the manufacturing method and manufacturing apparatus having the above-described configuration, an oxidized region can be formed by partially anodizing a plurality of portions of the metal back layer. Therefore, compared to the conventional method, the characteristics such as the withstand voltage of the dividing portion of the metal back can be improved, and the cutting can be performed at a very high speed with a relatively simple method and apparatus. Thereby, the discharge current suppressing structure can be realized at a practical level.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an FED to which the present invention is applied will be described in detail with reference to the drawings.
As shown in FIGS. 1 and 2, the FED includes a front substrate 2 and a rear substrate 1 each made of rectangular glass, and these substrates are arranged to face each other with a gap of 1 to 2 mm. The front substrate 2 and the rear substrate 1 are joined to each other through a rectangular frame-shaped side wall 3, and a flat rectangular vacuum envelope whose inside is maintained at a high vacuum of about 10 ⁻⁴ Pa or less. The device 4 is configured.
[0025]
A phosphor screen 6 is formed on the inner surface of the front substrate 2. As will be described later, the phosphor screen 6 is composed of a phosphor layer that emits red, green, and blue light and a matrix-shaped light shielding layer. A metal back layer 7 that functions as an anode electrode is formed on the phosphor screen 6. During the display operation, a predetermined anode voltage is applied to the metal back layer 7.
[0026]
On the inner surface of the back substrate 1, a large number of electron-emitting devices 8 that emit an electron beam for exciting the phosphor layer are provided. These electron-emitting devices 8 are arranged in a plurality of columns and a plurality of rows corresponding to each pixel. The electron-emitting device is driven by a matrix wiring (not shown).
[0027]
In addition, a large number of spacers 10 formed in a plate shape or a column shape are arranged between the back substrate 1 and the front substrate 2 in order to withstand atmospheric pressure.
An anode voltage is applied to the phosphor screen 6 via the metal back layer 7, and the electron beam emitted from the electron emitter 8 is accelerated by the anode voltage and collides with the phosphor screen 6. As a result, the corresponding phosphor layer emits light and an image is displayed.
[0028]
Next, the phosphor screen 6 and the metal back layer 7 in the FED will be described in detail.
As shown in FIGS. 3 and 4, the fluorescent screen 6 provided on the inner surface of the front substrate 2 has a light shielding layer 22. The light shielding layer 22 is formed of, for example, a large number of stripe portions 22 a arranged in parallel with a predetermined gap and a rectangular frame portion 22 b extending along the periphery of the phosphor screen 6. The phosphor screen 6 has a large number of phosphor layers R, G, and B that are formed between the stripe portions 22a of the light shielding layer 22 and emit light in red, blue, and green, respectively.
[0029]
In addition, the metal back layer 7 formed on the phosphor screen 6 has a plurality of non-oxidized regions 7a and a plurality of oxidized regions 7b. That is, the non-oxidized regions 7a of the metal back layer 7 are each formed in an elongated stripe shape, extend in parallel with each other with a predetermined gap, and mainly overlap the phosphor layers R, G, B. . The oxidized regions 7b are formed in a stripe shape and are located between the non-oxidized regions 7a. The oxidized region 7 b is formed on the light shielding layer 22. It is desirable that the oxidized region 7b does not protrude to the phosphor layers R, G, B side, and a part of the non-oxidized region 7a is also formed on the light shielding layer 22 in order to take a margin. Is preferred.
[0030]
Here, the oxidized region 7b means a region oxidized in the layer thickness direction from one surface of the metal back layer 7 to the other surface, and the non-oxidized region 7a does not mean that there is no oxidation at all. Only the surface layer of the metal back layer means a naturally oxidized region. The oxidized region 7b is formed by partially anodizing the metal back layer 7 as will be described later.
[0031]
When the metal back layer 7 is divided by the oxidized region 7b, it becomes difficult to supply an electron beam current to the entire surface of the metal back layer. Therefore, the non-oxidized region 7 a is connected to the common electrode 51 through the resistor 50. A high voltage supply unit 52 is formed in a part of the common electrode 51, and a high voltage is applied by an appropriate means. Thereby, the beam current can be supplied to the entire surface of the metal back layer while ensuring the discharge current suppressing function. Such a technique is disclosed in Patent Document 2 described above.
[0032]
The metal back layer 7 is formed by a thin film process such as vapor deposition. At this time, since the phosphor screen 6 has irregularities, it is difficult to form a mirror surface if the metal back layer 7 is directly formed on the phosphor screen 6. Therefore, a method of performing vapor deposition after smoothing the phosphor screen 6 with lacquer or the like is well known. As another method, a method in which a sheet on which aluminum is deposited is transferred by heating can also be used. The film thickness of the metal back layer 7 is preferably about 50 to 200 nm in consideration of electron beam transmittance and film strength. In the present embodiment, the metal back layer 7 is made of a metal containing either aluminum or titanium. This is because the density is low, the electron transmittance is high, the cost is low, the uniformity of the reflection spectrum is high, and anodization is possible.
[0033]
In order to form the oxidized region 7b in the metal back layer 7, anodic oxidation using the metal back layer as an anode is used. Hereinafter, the anodic oxidation of the metal back layer 7 will be described in detail.
[0034]
As shown in FIG. 5, a front substrate 2 on which a phosphor screen 6 and a metal back layer 7 are formed, and a processing substrate 30 are prepared. Various metals can be used for the processing substrate as the processing member. However, considering thermal expansion coefficient matching with glass, an Fe—Ni alloy, titanium, or the like is preferable. As shown in FIG. 6, a plurality of strip-like elongated grooves 32 are formed on one surface of the processing substrate 30 and extend in parallel with each other at a predetermined interval. The surface of the processing substrate 30 and the side surfaces of the grooves 32 are covered with a high resistance layer 36. Here, the reason why the high resistance layer 36 is provided is to secure a necessary cathode-anode distance. Basically, it is preferable to use an insulating layer rather than a high resistance, but it is not indispensable to use an insulating layer, and depending on the film thickness, it is a film of about 10 ⁸ Ω / □ or more. good. Of course, it is not necessary to provide a high resistance layer on all side surfaces of the groove 32. Furthermore, if the swell amount of the electrolyte solution described later can be sufficiently increased, the high resistance layer can be eliminated.
[0035]
As another configuration, as shown in FIG. 7, a plurality of ribs 40 formed of an insulating material are provided on the surface of a base member 38 having conductivity on at least the surface to constitute a processing substrate 30. May be. The base member 38 may be made of metal, but considering the coefficient of thermal expansion, it is preferable to use a material in which a conductive film is formed on the surface of the same glass as the front substrate 2 by printing or other various film forming methods. is there. Various methods can be applied to the formation of the rib 40. For example, methods such as multilayer printing of insulating paste, removal of regions other than ribs by sandblasting after forming a low melting point glass layer, exposure, development, and embedding of insulating paste using a photosensitive dry film can be applied.
[0036]
Further, since the processing substrate 30 does not need to be fired at a high temperature, it is also possible to use rubber or resin instead of a glass-based paste.
Subsequently, as shown in FIG. 8A, the groove 42 is filled with an electrolytic solution 42 so as to rise slightly from the surface of the processing substrate 30. As the electrolytic solution 42, various general electrolytic solutions for anodization can be used, and sulfuric acid, oxalic acid, and phosphoric acid are preferable. In addition, when the viscosity of the electrolytic solution 42 is too low and the amount d of swelling is insufficient, various viscosity modifiers are mixed to adjust the viscosity. The amount d of swelling is preferably about 0.02 to 0.1 mm.
[0037]
Subsequently, as shown in FIG. 8B, the front substrate 2 and the processing substrate are aligned while the position where the oxidation region 7b of the front substrate 2 is to be formed corresponds to the groove 32 of the processing substrate 30. 30 is brought close to each other, and the electrolytic solution 42 is brought into contact with the metal back layer 7.
[0038]
In this state, a voltage of about 10 to 100 V is applied by the power source 44 as a voltage supply unit using the metal back layer 7 as an anode and the processing substrate 30 itself as an anode electrode. Thereby, the region in contact with the electrolytic solution 42 is anodized within about 2 minutes, and the oxidized region 7b is formed.
[0039]
Thereafter, the processing substrate 30 is released, and the front substrate 2 is dried and fired. Through the above steps, the front substrate 2 having the metal back layer 7 having the desired pattern of oxidized and non-oxidized regions is obtained.
[0040]
According to the FED configured as described above, the metal back layer 7 is electrically divided by the plurality of oxidized regions 7b, and the adjacent non-oxidized regions 7a can be insulated. Further, if the resistance value of the shielding layer 22 is controlled, the resistance value between the non-oxidized regions 7a can be set to a desired value. In some cases, such resistance value control may be performed in order to optimize the characteristics.
[0041]
With the above configuration, the effective impedance of the phosphor screen 6 can be increased, and even when a discharge occurs between the front substrate 2 and the rear substrate 1, the discharge current at that time can be sufficiently reduced. Accordingly, it is possible to obtain an FED capable of preventing damage due to discharge of the phosphor screen 6 and the electron-emitting device 8.
[0042]
In this method, since the metal back layer 7 is not partially removed, the metal back layer remains a single film. For this reason, unlike the case of laser cutting, no protrusion is formed at the boundary of the divided portion, and the withstand voltage of the divided portion is improved. In one example, the withstand voltage in the same width was improved by 1.7 times. As this withstand voltage is higher, the voltage distribution in the metal back layer during discharge can be made steeper, and the discharge current can be reduced. In addition, since a required withstand voltage can be obtained with a narrower dividing width, it is advantageous for achieving high definition. Furthermore, even if the anode voltage is increased, discharge can be prevented from occurring at the dividing portion, so that the anode voltage can be increased.
[0043]
Further, in the case of laser cutting, the withstand voltage between the rear substrate and the rear substrate could not be sufficiently increased because the quality of the divided portion was poor. Therefore, it is necessary to further provide a coat layer that covers the divided portion. The coat layer is formed by printing. However, since the metal back layer is a very thin film, it is difficult to sufficiently withstand the printing process. However, in this embodiment, since the edge portion with poor quality cannot be formed, the withstand voltage is not particularly deteriorated. For this reason, the manufacturing process can be simplified.
[0044]
Further, in this method, the entire metal back layer can be divided within about 2 minutes. This is significantly shorter in processing time than laser cutting. Furthermore, the necessary apparatus is relatively simple and is extremely excellent in terms of mass productivity.
[0045]
The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. For example, the pattern of the oxidized and non-oxidized regions in the metal back layer 7 is not limited to the stripe pattern described above, and can be an arbitrary pattern. For example, the non-oxidized region 7a may be formed in a zigzag pattern. The oxidized region 7b may be a matrix pattern. In this case, as shown in FIG. 9, the grooves 32 of the processing substrate 30 are also formed in a matrix corresponding to the oxidized regions 7b.
[0046]
The processing substrate is not limited to a substrate having the same size as the front substrate, and may be divided into a plurality of members or may be scanned with a small area member. The larger the member, the more difficult it is to ensure accuracy. Therefore, the size of the processing substrate may be appropriately selected in consideration of accuracy. Moreover, you may make it rotate a roller-shaped member as a member for a process. In this case, there is an advantage that the electrolytic solution can be continuously filled.
[0047]
The above-described embodiment is based on the principle of so-called intaglio printing, but printing includes other principles such as letterpress printing, screen printing, offset printing, and any of these principles can be applied. is there. According to the principle of letterpress printing, the electrolytic solution may be attached to the protrusions instead of the grooves and brought into contact with the metal back layer. In the case of screen printing, a conductive mesh may be used and filled with a paste containing an electrolytic solution.
[0048]
Also, instead of using the surface tension to bring the electrolyte into contact with the metal back layer, the electrolyte is soaked into a permeable and soft member such as a cloth, and this is brought into contact with the metal back layer. It is also possible to make it.
[0049]
Therefore, in general, various methods are conceivable as long as the electrolytic solution is selectively brought into contact with the oxidized region of the metal back layer.
[0050]
In general, a structure in which an electrolytic solution is selectively brought into contact with the oxidized region of the metal back layer may be provided so that a voltage for anodization can be applied.
[0051]
【The invention's effect】
As described above, according to the present invention, the metal back layer can be divided by a highly practical method, and even when a discharge occurs between the front substrate and the rear substrate, It is possible to provide an image display device capable of sufficiently suppressing current and preventing damage due to discharge, a manufacturing method thereof, and an image display device manufacturing apparatus.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an FED according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the FED taken along line AA in FIG.
FIG. 3 is a plan view showing a phosphor screen and a metal back layer of a front substrate in the FED.
4 is a cross-sectional view of the front substrate along the line BB in FIG. 3;
FIG. 5 is an exploded perspective view showing a front substrate and a processing substrate.
6 is a cross-sectional view of the processing substrate along line CC in FIG. 5;
FIG. 7 is a cross-sectional view showing a processing substrate according to a modification.
FIG. 8 is a cross-sectional view showing a step of anodizing the metal back layer.
FIG. 9 is a perspective view showing a modification of the processing substrate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Back substrate 2 ... Front substrate 3 ... Side wall 4 ... Vacuum envelope 6 ... Phosphor screen 7 ... Metal back layer 7a ... Non-oxidized region 7b ... Oxidized region 8 ... Electron emission element 22 ... Light shielding layer 22a ... Stripe part 22b ... Frame-shaped portion 30 ... processing substrate 32 ... groove 38 ... base member 42 ... electrolyte

Claims (9)

A front substrate having a phosphor screen including a phosphor layer and a light-shielding layer and a metal back layer made of a thin film provided on the phosphor screen;
A rear substrate disposed opposite to the front substrate and having a plurality of electron-emitting devices that emit electrons toward the phosphor screen; and
The metal back layer includes a plurality of oxidized regions anodized in the layer thickness direction from one surface of the metal back layer to the other surface, and a plurality of non-oxidized regions , each having the metal back layer as an anode. An image display device characterized by comprising: The image display device according to claim 1, wherein the oxidation region is positioned to face the light shielding layer on the phosphor surface. 3. The image display device according to claim 1, wherein the metal back layer is formed of a metal including aluminum or titanium. A front substrate having a phosphor screen including a phosphor layer and a light-shielding layer and a metal back layer made of a thin film provided on the phosphor screen, and disposed opposite to the front substrate, and the phosphor screen In a manufacturing method of an image display device comprising a rear substrate on which a plurality of electron-emitting devices that emit electrons toward the substrate are arranged,
A metal back layer is formed on the phosphor surface of the front substrate,
Anodizing a plurality of portions of the metal back layer to form a plurality of oxidized regions oxidized in the layer thickness direction from one surface of the metal back layer to the other surface and a plurality of non-oxidized regions. A method for manufacturing an image display device. Prepare an electrolyte solution in contact with a plurality of locations of the metal back layer, and an electrode facing the plurality of locations of the metal back layer via the electrolyte solution,
5. The method of manufacturing an image display device according to claim 4, wherein a voltage is applied between the metal back layer and the electrode using the metal back layer as an anode and the electrode as a cathode. 6. The method for manufacturing an image display device according to claim 5, wherein any one of sulfuric acid, oxalic acid, and phosphoric acid is used as the electrolytic solution. In the manufacturing apparatus which manufactures the image display apparatus of Claim 1,
A processing member having a structure in which the electrolytic solution is selectively brought into contact with the oxidized region of the metal back layer, and a cathode for supplying a potential to the electrolytic solution;
A voltage supply unit for applying a voltage between the metal back layer serving as an anode and the cathode;
An apparatus for manufacturing an image display device, comprising: The apparatus for manufacturing an image display device according to claim 7, wherein the processing member includes a conductive member that forms a cathode and has a groove filled with an electrolytic solution. The processing member includes a base member having conductivity on the surface and constituting a cathode, and a plurality of ribs that are provided on the base member and that form grooves filled with an electrolytic solution. The apparatus for manufacturing an image display device according to claim 7, wherein:

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