JP2005011701A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device reducing damage caused by discharge and enhancing reliability. <P>SOLUTION: A front substrate 2 of the image display device has a fluorescent screen 6 and a metal back layer 7 laminated on the fluorescent screen. A plurality of electron emission elements emitting electrons to the fluorescent screen are arranged on a back substrate 1 facing the fluorescent substrate. The metal back layer, in which a first resistance layer 30 and a second resistance layer 32 having lower resistance value than the first resistance layer are laminated thereon, the first resistance layer is laminated on the whole surface of the fluorescent screen, and the second resistance layer is divided into a plurality of divided regions 7a at certain intervals, is laminated on the fluorescent layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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 including a pair of substrates arranged to face each other.
[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. 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.
[0005]
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.
[0006]
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.
[0007]
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.
[0008]
When discharge occurs, the electron-emitting device, the phosphor screen, and the drive circuit may be destroyed or deteriorated. 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.
[0009]
On the other hand, instead of preventing discharge, it is conceivable to suppress the discharge scale so that the influence on the electron-emitting device, the phosphor screen, and the drive circuit can be ignored even if the discharge occurs. As a technique related to such a concept, a technique is disclosed in which a notch is formed in a metal back provided on the phosphor screen to form a zigzag pattern or the like, and the effective impedance of the phosphor screen is increased (for example, Patent Document 1). Further, a technique for applying a high voltage by dividing a metal back and connecting it to a common electrode through a resistance member is disclosed (for example, Patent Document 2).
[0010]
[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]
In such a configuration in which the metal back is divided, a large voltage Vc is generated between the divided metal backs during discharge. Therefore, increasing the breakdown voltage between the metal backs is an important issue. Vc can be controlled by a resistance Rc between the metal backs. Therefore, controlling Rc is also an important issue. In order to set the resistance, there may be a method of imparting a desired resistance to the light shielding layer between the phosphors, or a method of separately forming a resistance layer for adjusting the resistance between the metal backs. However, with such a method, sufficient characteristics may not be obtained due to material and process limitations.
[0013]
The present invention is for solving such a problem, and its purpose is to suppress the scale of discharge generated between the front substrate and the rear substrate, and to destroy, deteriorate and degrade the electron-emitting device and the phosphor screen. An object of the present invention is to provide an image display device which can prevent circuit destruction and has improved reliability.
[0014]
[Means for Solving the Problems]
In order to solve the above problems, 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 provided on the phosphor screen. And a back substrate on which a plurality of electron-emitting devices that emit electrons toward the phosphor screen are disposed, and the metal back layer includes a first resistance layer. And a second resistance layer having a resistance lower than that of the first resistance layer, the first resistance layer is provided over the entire surface of the phosphor screen, and the second resistance layer is spaced from each other. It is divided into a plurality of divided areas arranged side by side, and is provided so as to overlap the phosphor layer.
[0015]
Thereby, an image display device with improved reliability can be obtained. At the same time, the anode voltage can be increased and the gap between the front substrate and the rear substrate can be reduced, so that an image display device with improved display characteristics such as luminance and resolution can be obtained.
[0016]
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.
[0017]
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.
[0018]
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 devices are driven by wiring 21 arranged in a matrix. In addition, a large number of spacers 10 formed in a plate shape or a column shape are disposed between the back substrate 1 and the front substrate 2 in order to support the atmospheric pressure acting on these substrates.
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. Thereby, the corresponding phosphor layer emits light and an image is displayed.
[0019]
Next, the phosphor screen 6 and the metal back layer 7 in the FED will be described in detail. In the present invention, the term “metal back layer” is used. However, this layer is not limited to metal, and various materials can be used. However, in this application, the term metal back layer is used for convenience.
[0020]
As shown in FIGS. 3 and 4, the phosphor screen 6 provided on the inner surface of the front substrate 2 has a large number of rectangular phosphor layers R, G, and B that emit red, blue, and green light. . When the longitudinal direction of the front substrate 2 is the first direction X and the width direction orthogonal thereto is the second direction Y, the phosphor layers R, G, and B are alternately arranged with a predetermined gap in the first direction X. The phosphor layers of the same color are arranged with a predetermined gap in the second direction. The fluorescent screen 6 has a black light shielding layer 22. The black light shielding layer 22 includes a rectangular frame portion 22a extending along the peripheral edge of the front substrate 2, and a matrix portion 22b extending in a matrix between the phosphor layers R, G, and B inside the rectangular frame portion. Have.
[0021]
As shown in FIGS. 4 to 6, the metal back layer 7 formed on the phosphor screen 6 includes a first resistance layer 30 having a high resistance and a second resistance layer 32 having a lower resistance than the first resistance layer. It is formed by stacking. The first resistance layer 30 has a rectangular shape, and is formed uniformly on the entire surface of the phosphor screen 6 except for the peripheral edge. At one corner of the first resistance layer 30, a power supply terminal portion 34 that applies a voltage to the metal back layer 7 is formed.
[0022]
The second resistance layer 32 is provided on the first resistance layer 30 and is formed as a dividing resistance layer. That is, the second resistance layer 32 is divided in the first direction X and the second direction Y, and has a large number of rectangular divided regions 7a arranged in the first direction and the second direction with a gap therebetween. The divided region 7a of the second resistance layer 32 has an arrangement pattern that matches the arrangement pattern of the phosphor layers R, G, and B, and is provided at a position overlapping the phosphor layers R, G, and B. . If necessary, another material layer may be formed in the gap between the divided regions 7a.
[0023]
Both the first resistance layer and the second resistance layer are formed by a thin film process such as vapor deposition. As is well known, it is preferable to perform a smoothing process using lacquer or the like before vapor deposition. The second resistance layer is formed into a desired pattern by a method of performing masking during vapor deposition or the like, or a method of selectively dividing only the second resistance layer.
[0024]
The thickness of the first resistance layer is preferably about 20 to 200 nm. This is determined in consideration of the resistance value and the electron transmission ability. The thickness of the second resistance layer is preferably about 20 to 200 nm. This is determined in consideration of electron permeability and film strength.
[0025]
The higher the sheet resistance ρs1 of the first resistance layer, the smaller the discharge current. As a result of the experiment, it was confirmed that ρs1 needs to be 1E3Ω / □ or more in order to obtain a certain discharge current suppression effect. The sheet resistance ρs2 of the second resistance layer needs to be smaller than ρs1. In practice, it is sufficient to use aluminum, which is 1 Ω / □ or less.
[0026]
According to the FED configured as described above, since the resistance between the divided metal backs can be formed by a thin film process, the range of selection of materials is widened and can be set to a desired value. In addition, it is easy to increase the breakdown voltage between the divided metal backs. Therefore, the discharge current can be made smaller than before without causing a discharge between the metal backs.
[0027]
Thereby, damage to the fluorescent screen 6, the electron-emitting device 8, and the drive circuit can be suppressed. Therefore, the anode voltage can be increased, and the gap between the front substrate 2 and the rear substrate 1 can be reduced, and an image display device with improved display characteristics such as luminance and resolution and reliability can be obtained. Can do. In addition, phosphor degradation becomes a problem as the anode voltage is low. However, since the anode voltage can be set higher as described above, phosphor degradation can be mitigated and the life of the product can be extended.
[0028]
The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention. For example, in the above-described embodiment, the first resistance layer of the metal back layer 7 is provided on the phosphor screen. However, the second resistor layer 32 is formed on the phosphor screen and is overlaid on the second resistor layer. The first resistance layer 30 may be provided.
[0029]
In addition, the second resistive layer of the metal back layer can be variously changed in the arrangement pattern of the divided regions according to the arrangement pattern of the phosphor layers. For example, the divided region of the second resistance layer is not limited to the matrix shape described above, but is a strip shape in which elongated striped divided regions are arranged with a gap, or an elongated strip-shaped divided region as described in Patent Document 1. It may be formed in a zigzag pattern that is folded in a bellows shape. The term division in the present invention includes such a configuration. In addition, the dimensions, materials, and the like of each component are not limited to the numerical values and materials shown in the above-described embodiment, and can be variously selected as necessary.
[0030]
【The invention's effect】
As described above, according to the present invention, even when a discharge occurs between the front substrate and the back substrate, the discharge scale at that time can be sufficiently suppressed, and the damage due to the discharge is greatly reduced and the reliability is improved. An image display device can be provided.
[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.
FIG. 4 is an enlarged plan view showing a part of the front substrate.
FIG. 5 is a plan view showing a metal back layer provided on the front substrate.
FIG. 6 is an enlarged plan view showing a part of the metal back layer.
FIG. 7 is an enlarged cross-sectional view showing a part of the front substrate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Back substrate, 2 ... Front substrate, 3 ... Side wall,
6 ... phosphor screen, 7 ... metal back layer, 8 ... electron-emitting device,
22 ... light shielding layer, 30 ... first resistance layer, 32 ... second resistance layer,
32a ... divided area

Claims (5)

A phosphor screen including a phosphor layer and a light shielding layer, a metal back layer provided on the phosphor screen, and a front substrate having
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 is formed by overlapping a first resistance layer and a second resistance layer having a lower resistance than the first resistance layer, and the first resistance layer is provided over the entire surface of the phosphor screen. 2. The image display device according to claim 1, wherein the second resistance layer is divided into a plurality of divided regions arranged with a gap between each other, and is provided so as to overlap the phosphor layer. The image display device according to claim 1, wherein the first resistance layer is provided between the phosphor screen and the second resistance layer. The image display device according to claim 1, wherein the second resistance layer is divided into a first direction and a second direction orthogonal to the first direction. The phosphor layer has an array pattern arranged with a gap in the first direction and the second direction, and the divided region of the second resistance film has an array pattern that matches the phosphor layer. The image display device according to claim 1, wherein the image display device is an image display device. 5. The image display device according to claim 1, wherein the first resistance layer has a sheet resistance of 1E3Ω / □ or more.

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