JP3825703B2 - Image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image display apparatus having a substrate disposed oppositely and a plurality of electron sources disposed on an inner surface of one substrate.
[0002]
[Prior art]
In recent years, an image display device for high-definition broadcasting or a high-resolution image accompanying this has been desired, and the screen display performance is required to be more severe. In order to achieve these demands, it is essential to flatten the screen surface and increase the resolution, and at the same time, it is necessary to reduce the weight and thickness.
[0003]
As an image display device that satisfies the above-described demand, for example, a flat display device such as a field emission display (hereinafter referred to as FED) has attracted attention. This FED has a first substrate and a second substrate which are arranged to face each other with a predetermined gap, and these substrates are joined to each other directly or via a rectangular frame-shaped side wall to form a vacuum outside. It constitutes an envelope. A phosphor layer is formed on the inner surface of the first substrate, and a plurality of electron-emitting devices are provided on the inner surface of the second substrate as electron sources that excite the phosphor layer to emit light.
[0004]
In order to support an atmospheric pressure load applied to the first substrate and the second substrate, a plurality of spacers are provided as support members between these substrates. In this FED, when an image is displayed, an anode voltage is applied to the phosphor layer, and an electron beam emitted from the electron-emitting device is accelerated by the anode voltage to collide with the phosphor layer. Flash and display image.
[0005]
In such an FED, the size of the electron-emitting device is on the order of micrometers, and the distance between the first substrate and the second substrate can be set on the order of millimeters. For this reason, compared with the cathode ray tube (CRT) currently used as a display of a television or a computer, it becomes possible to achieve higher resolution, lighter weight, and thinner thickness of the image display device.
[0006]
[Problems to be solved by the invention]
In the image display apparatus as described above, in order to obtain practical display characteristics, it is desirable to use a phosphor similar to a normal cathode ray tube and set the anode voltage to several kV or more. However, the gap between the first substrate and the second substrate cannot be so large from the viewpoint of resolution, support member characteristics, manufacturability, and the like, and needs to be set to about 1 to 2 mm. Therefore, when the electrons emitted from the second substrate collide with the phosphor screen formed on the first substrate, secondary electrons and reflected electrons are emitted, and these secondary electrons and reflected electrons collide with the spacer. The spacer disposed between the substrates is charged by the electric field. In the acceleration voltage in the FED, the spacer is generally positively charged, and the electron beam emitted from the electron-emitting device is attracted to the spacer and deviates from the original trajectory. As a result, there is a problem that electron beam mislanding occurs in the phosphor layer and the color purity of the display image is deteriorated.
[0007]
The present invention has been made in view of the above points, and an object of the present invention is to provide an image display apparatus that prevents an orbital shift of an electron beam and has improved image quality.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an image display device according to the present invention is disposed opposite to a first substrate having an image display surface with a gap between the first substrate and excites the image display surface. A second substrate provided with a plurality of electron sources; a first surface facing the first substrate; a second surface facing the second substrate; and a plurality of apertures respectively facing the electron sources A grid provided between the first and second substrates, a plurality of columnar first spacers standing on the first surface of the grid and in contact with the first substrate, and a second surface of the grid A plurality of columnar second spacers standing on the second substrate and contacting the second substrate,
The second spacer has a conductive layer that is formed on an end surface on the second substrate side and repels an electron beam emitted from the electron source, and the height of the first spacer is the height of the second spacer. It is characterized by being formed lower than the height .
[0009]
According to the image display device configured as described above, electrons emitted from the electron source located in the vicinity of the spacer are temporarily repelled from the spacer by the electric field formed by the conductive layer of the spacer, that is, After taking a trajectory in a direction away from the spacer, the trajectory is taken in a direction approaching the spacer by being sucked by the spacer. The repulsion and suction cancel out the electron orbital deviation, and the electrons emitted from the electron source finally reach the target position on the image display surface. As a result, it is possible to obtain an image display device with reduced color purity due to electron mislanding and improved image quality.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment in which the present invention is applied to a surface conduction electron-emitting device (hereinafter referred to as SED) which is a kind of FED as a flat display device will be described in detail below with reference to the drawings.
As shown in FIGS. 1 to 3, this SED includes a first substrate 12 and a second substrate 10 each made of rectangular glass as transparent insulating substrates, and these plates have a thickness of about 1.0 to 2.0 mm. Are placed opposite each other with a gap. The second substrate 10 is formed to have a slightly larger size than the first substrate 12. The first substrate 12 and the second substrate 10 are joined to each other through a rectangular frame-shaped side wall 14 made of glass to constitute a flat rectangular vacuum envelope 15.
[0011]
A phosphor screen 16 is formed on the inner surface of the first substrate 12 as an image forming surface. The phosphor screen 16 is configured by arranging phosphor layers R, G, B, and a black colored layer 11 that emit red, blue, and green light upon collision of electrons. These phosphor layers R, G, and B are formed in stripes or dots. A metal back 17 made of aluminum or the like is formed on the phosphor screen 16. A transparent conductive film or a color filter film made of, for example, ITO may be provided between the first substrate 12 and the phosphor screen.
[0012]
On the inner surface of the second substrate 10, a number of surface conduction electron-emitting devices 18 that emit electron beams are provided as electron sources that excite the phosphor layer of the phosphor screen 16. These electron-emitting devices 18 are arranged in a plurality of columns and a plurality of rows corresponding to each pixel. Each electron-emitting device 18 includes an electron emitting portion (not shown) and a pair of device electrodes for applying a voltage to the electron emitting portion. On the second substrate 10, a large number of wirings (not shown) for applying a voltage to the electron-emitting devices 18 are provided in a matrix.
[0013]
The side wall 14 functioning as a bonding member is sealed to the peripheral edge of the second substrate 10 and the peripheral edge of the first substrate 12 by, for example, a sealing material 20 such as low melting glass, low melting metal, etc. The second substrate is joined.
[0014]
As shown in FIGS. 2 and 3, the SED includes a spacer assembly 22 disposed between the second substrate 10 and the first substrate 12. In the present embodiment, the spacer assembly 22 includes a plate-like grid 24 and a plurality of columnar spacers that are integrally provided on both sides of the grid.
[0015]
More specifically, the grid 24 has a first surface 24a facing the inner surface of the first substrate 12 and a second surface 24b facing the inner surface of the second substrate 10, and is arranged in parallel with these substrates. A large number of electron beam passage holes 26 and a plurality of spacer openings 28 are formed in the grid 24 by etching or the like. The electron beam passage apertures 26 functioning as apertures in the present invention are arranged facing the electron-emitting devices 18 respectively. Further, the spacer openings 28 are located between the electron beam passage holes and arranged at a predetermined pitch.
[0016]
The grid 24 is formed to have a thickness of 0.1 to 0.25 mm using, for example, an iron-nickel metal plate, and an oxide film made of an element constituting the metal plate by oxidation treatment, for example, An oxide film made of Fe ₃ O ₄ and NiFe ₃ O ₄ is formed. Further, a high resistance film is formed on the surface of the grid 24 by applying and baking a high resistance material made of glass or ceramic, and the resistance of the high resistance film is set to E + 8Ω / □ or more.
[0017]
The electron beam passage hole 26 is formed in a rectangular shape of, for example, 0.15 to 0.25 mm × 0.15 to 0.25 mm. The spacer opening 28 is formed with a diameter of about 0.2 to 0.5 mm, for example. The high resistance film described above is also formed on the wall surface of the electron beam passage hole 26 provided in the grid 24.
[0018]
On the first surface 24 a of the grid 24, a first spacer 30 a is integrally provided so as to overlap each spacer opening 28, and the extended end thereof is a black colored layer 11 of the metal back 17 and the phosphor screen 16. Via the inner surface of the face plate 12. In the present embodiment, the extending end of each first spacer 30a is in contact with the metal back 17 through the indium layer 31 functioning as a height relaxing layer. Here, the height relaxing layer has no influence on the trajectory of the electron beam, and is not limited to a metal as long as it has an appropriate hardness that has a relaxing effect on the height variation of the spacer. .
[0019]
A second spacer 30 b is integrally provided on the second surface 24 b of the grid 24 so as to overlap each spacer opening 28, and its extending end is in contact with the inner surface of the second substrate 10. . The spacer openings 28, the first and second spacers 30a and 30b are coaxially aligned with each other, and the first and second spacers are integrally connected to each other through the spacer openings 28. Yes.
Each of the first and second spacers 30a and 30b is formed in a tapered shape with a diameter decreasing from the grid 24 side toward the extending end.
[0020]
For example, each first spacer 30a is formed so that the diameter of the base end located on the grid 24 side is about 0.4 mm, the diameter of the extended end is about 0.3 mm, and the height is about 0.4 mm. The two spacers 30b are formed so that the diameter of the base end located on the grid 24 side is about 0.4 mm, the diameter of the extended end is about 0.25 mm, and the height is about 1.0 mm. Thus, the height of the first spacer 30a is formed to be lower than the height of the second spacer 30b, and the height of the second spacer is about 4/3 times the height of the first spacer, preferably It is set to 2 times or more.
[0021]
Then, the first spacer 30a and the second spacer 30b are coaxially aligned and integrally provided with the spacer opening 28, whereby the first and second spacers are connected to each other through the spacer opening, and the grid 24 is connected from both sides. It is formed integrally with the grid 24 in a sandwiched state.
[0022]
In the present embodiment, the surface resistance of the first spacer 30a and the second spacer 30b is 5 × 10 ¹³ Ω, and the outer surface of the tip of each second spacer 30b, that is, the end on the second substrate 10 side. For example, a conductive layer 33 made of a refractory metal such as platinum, tungsten, iridium, rhenium, osmium, ruthenium or conductive glass containing these metals is formed. A metal such as indium, aluminum, or copper can be used as the conductive layer 33. However, when discharge occurs, if the melting temperature is low, the metal may melt and not perform its original function, and a high melting point metal is used. Is preferable.
[0023]
When the height of the second spacer 30b along the direction perpendicular to the second substrate 10 is H and the height of the formation range of the conductive layer 33 along the direction perpendicular to the second substrate 10 is h, The height h of the conductive layer is
h = H × 0.2 × a
Is formed. Here, a = 0.9 to 1.1, indicating an allowable error range.
[0024]
The conductive layer 33 is formed by the following method, for example. After the first and second spacers 30a and 30b are formed on the grid 24, a mask 40 is provided on the first surface 24a side of the grid so as to cover the entire surface of the first spacer 30a, as shown in FIG. A mask 42 is provided on the second surface 24b side so that only the tip of the second spacer 30b is exposed. In this state, the conductive layer 33 is formed on the exposed tip surface of the second spacer 30b by vacuum deposition, sputtering, ion plating, spray coating, or the like. Thereafter, the masks 40 and 42 are removed.
[0025]
As shown in FIGS. 2 and 3, the spacer assembly 22 configured as described above is disposed between the first substrate 12 and the second substrate 10. The first and second spacers 30a and 30b are in contact with the inner surfaces of the first substrate 12 and the second substrate 10 to support the atmospheric pressure load acting on these substrates, and the distance between the substrates is a predetermined value. To maintain.
[0026]
As shown in FIG. 2, the SED includes a voltage supply unit 50 that applies a voltage to the grid 24 and the metal back 17 of the first substrate 12. The voltage supply unit 50 is connected to the grid 24 and the metal back 17, and applies a voltage of 12 kV to the grid 24 and 10 kV to the metal back 17, for example. That is, the voltage applied to the grid 24 is set higher than the voltage applied to the face plate 12, and is set within, for example, 1.25 times.
[0027]
In this SED, when displaying an image, an anode voltage is applied to the phosphor screen 16 and the metal back 17, and the electron beam B emitted from the electron-emitting device 18 is accelerated by the anode voltage to the phosphor screen 16. Collide. Thereby, the phosphor layer of the phosphor screen 16 is excited to emit light, and an image is displayed.
[0028]
According to the SED configured as described above, the electron beam B emitted from the electron-emitting device 18 located in the vicinity of the second spacer 30b is temporarily separated from the spacer by the electric field formed by the conductive layer 33 of the second spacer. Heading toward the electron beam passage hole 26 while taking a trajectory in a repulsive direction, that is, a direction away from the second spacer. Thereafter, the electron beam B is attracted by the charged second spacer 30b and the first spacer 30a and takes a trajectory in a direction approaching these spacers. The repulsion and suction cancel out the orbital deviation of the electron beam B, and the electron beam B emitted from the electron-emitting device 18 finally reaches the target phosphor layer of the phosphor screen 16.
[0029]
Specifically, the smaller the distance from the electron-emitting device to the spacer side wall, the larger the amount of electron beam moving to the spacer side. Conversely, when the distance to the spacer side wall is sufficiently large, the electron beam moves to the spacer side. The amount to do is negligible. The electron beam movement phenomenon occurs when secondary electrons and reflected electrons generated on the phosphor screen collide with the spacer. At this time, the secondary electron emission coefficient on the spacer surface is 1 or more from the acceleration voltage used in the SED. Thus, the spacer side wall is positively charged, and the electron beam is attracted to the spacer side.
[0030]
In this embodiment, instead of releasing the charging of the spacer side walls, a portion of the spacer surface, yet the setting takes that a conductive layer 33 on the end portion of the small electron velocity second substrate side, the electron beam spacer It is possible to easily form an electric field in the direction of repulsion, and by controlling the height of the conductive layer, the strength of the electric field can be changed and the amount of repulsion can be controlled. Therefore, like a grid of an electron gun in a CRT, a low potential portion and a high potential portion are alternately provided at a specific distance, a converging system using an electron lens is provided, and a complicated mechanism for converging an electron beam is provided. There is no need.
[0031]
Therefore, even when the first and second spacers 30a and 30b are charged and the electron beam B is attracted by these spacers, it is possible to prevent the orbital deviation of the electron beam. Thereby, mislanding of the electron beam B can be prevented, and as a result, deterioration of color purity can be reduced and image quality can be improved.
[0032]
The SED according to the present embodiment and the SED provided with the spacer not provided with the conductive layer 33 described above were prepared, and the amount of movement of the electron beam was compared. In the SED according to the present embodiment, in the vicinity of the spacer The movement amount of the electron beam passing through is suppressed by about 80%, and the color purity of the display image is also improved.
[0033]
Furthermore, according to the SED, the grid 24 is disposed between the first substrate 12 and the second substrate 10, and the height of the first spacer 30a is formed lower than the height of the second spacer 30b. ing. Accordingly, the grid 24 is positioned closer to the first substrate 12 side than the second substrate 10. Therefore, even when a discharge is generated from the first substrate 12 side, the grid 24 can suppress the discharge damage of the electron-emitting device 18 provided on the second substrate 10. Therefore, it is possible to obtain an SED having excellent pressure resistance against discharge and improved image quality.
[0034]
A SED having a spacer assembly in which the first spacer on the first substrate side is formed higher than the second spacer on the second substrate side and the SED according to the present embodiment are prepared, and these SEDs are operated for 1000 hours. When the damage state of the electron-emitting device was compared, in the SED according to the present embodiment, the damage of the electron-emitting device was reduced by 40%.
[0035]
Further, according to the SED having the above-described configuration, the grid 24 is formed by forming the first spacer 30a provided on the first substrate 12 side lower than the second spacer 30b provided on the second substrate 10 side. Even when the voltage applied to the first substrate 12 is made larger than the voltage applied to the first substrate 12, the electrons generated from the electron-emitting device 18 can reliably reach the phosphor screen side.
[0036]
Further, by providing the height relaxing layer, even if the plurality of first spacers 30a have a variation in height, the variation is absorbed by the relaxing layer, and the plurality of first spacers and the first substrate 12 are reliably in contact with each other. Can be made. Accordingly, the first and second spacers 30a and 30b can uniformly hold the gap between the first substrate 12 and the second substrate 10 over almost the entire area.
[0037]
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 present invention can be applied not only to an image display device having a grid but also to an image display device having no grid. In this case, the same effect as described above can be obtained by using columnar or plate-like spacers that are integrally formed and providing a conductive layer at the end of each spacer on the second substrate side.
[0038]
In addition, in this invention, the spacer forming material is not limited to the glass paste described above, and can be appropriately selected as necessary. Further, the diameter and height of the spacer, the dimensions and materials of the other components can be appropriately selected as necessary. Furthermore, the high resistance film provided on the grid surface and the second spacer is not limited to glass, tin oxide, and antimony oxide, and can be appropriately selected as necessary.
[0039]
On the other hand, the electron source is not limited to the surface conduction type electron-emitting device, and various types such as a field emission type and a carbon nanotube can be selected. Further, the present invention is not limited to the SED described above, but can be applied to various image display devices such as FED and PDP.
[0040]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide an image display apparatus that prevents an electron beam trajectory shift and has improved image quality.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an SED according to an embodiment of the present invention.
2 is a perspective view of the SED broken along the line AA in FIG. 1; FIG.
FIG. 3 is an enlarged sectional view showing the SED.
FIG. 4 is a diagram schematically showing a step of forming a spacer conductive layer in the SED.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... 2nd board | substrate 12 ... 1st board | substrate 14 ... Side wall 15 ... Vacuum envelope 16 ... Phosphor screen 18 ... Electron emission element 22 ... Spacer assembly 24 ... Grid 24a ... 1st surface 24b ... 2nd surface 26 ... Electron beam Passing hole 28 ... spacer opening 30 a ... first spacer 30 b ... second spacer 31 ... conductive layer 50 ... voltage supply section

Claims (7)

A first substrate having an image display surface;
A second substrate provided opposite to the first substrate with a gap and provided with a plurality of electron sources for exciting the image display surface;
A first surface facing the first substrate; a second surface facing the second substrate; and a plurality of apertures facing the electron source, respectively, provided between the first and second substrates. The grid,
A plurality of columnar first spacers standing on the first surface of the grid and in contact with the first substrate;
A plurality of columnar second spacers standing on the second surface of the grid and in contact with the second substrate;
It said second spacer have a conductive layer to repel the electron beams emitted from the second the electron source is formed on the end surface of the substrate,
An image display device , wherein the height of the first spacer is lower than the height of the second spacer . When the height of the second spacer along the direction perpendicular to the second substrate is H, and the height of the formation range of the conductive layer along the direction perpendicular to the second substrate is h, Height h is
h = H × 0.2 × a
a = 0.9 to 1.1
The image display device according to claim 1 , wherein the image display device is formed in the following manner. Each first spacer is erected on the first surface of the grid between the apertures, and each second spacer is erected on the second surface of the grid between the apertures, The image display device according to claim 1 , wherein the image display device is disposed coaxially with the first spacer. The surface of the grid, and on the inner surface of each aperture, the image display apparatus according to any one of claims 1 to 3, characterized in that the high-resistance film is formed. To the grid and the first substrate, an image display apparatus according to any one of claims 1 to 4, characterized in that it comprises a voltage supply unit for supplying different potentials from each other. The conductive layer is an image display apparatus according to any one of claims 1 to 5, characterized in that it is formed of a conductive glass containing particles of metal or film of an alloy or a metal and an alloy, . The image display device according to claim 6 , wherein the metal constituting the conductive layer is a refractory metal containing at least one of platinum, tungsten, iridium, rhenium, osmium, and ruthenium.

Images