Patent Grant
7965027
1. Field of the Invention
The present invention relates to an image display apparatus using an electron-emitting device such as a field emission electron-emitting device or a surface conduction electron-emitting device and a light-emitting substrate used for the image display apparatus. More particularly, the present invention relates to a light-emitting substrate having a substrate on which an electrode to which a high potential is applied and an electrode to which a low potential is applied are arranged, at an interval. The present invention also relates to an information display and a reproduction apparatus using the light-emitting substrate, such as a television.
2. Related Background Art
Up to now, there have been attempts to produce an image display apparatus such as a so-called flat panel display. In such a display, a substrate including a large number of electron-emitting devices such as field emission electron-emitting devices or surface conduction electron-emitting devices is opposed to a light-emitting substrate including a phosphor such as a fluorescent material that emits light by irradiation with electrons emitted from the electron-emitting devices.
The light-emitting substrate composing the image display apparatus generally includes the phosphor such as the fluorescent material and an anode electrode that covers the phosphor (or which is located between the phosphor and a transparent insulating substrate), which are formed above the transparent insulating substrate. The anode electrode is composed of a thin electroconductive film. In particular, the anode electrode disposed on a surface of the phosphor facing (or opposed to) a substrate having the electron-emitting devices is called a “metal back”. Note that the function of the anode electrode is to accelerate electrons emitted from the electron-emitting devices and to irradiate the phosphor with the electrons passed through the anode electrode. In order to, for example, sharpen a displayed image, the light-emitting substrate further includes a light absorbing layer which is called a “black matrix”, a “black stripe” or the like in some cases. When the light-emitting substrate includes the light absorbing layer, the phosphor is located in an opening provided in the light absorbing layer.
When a high-resolution and high-luminance image is to be obtained on the above-mentioned flat panel display, it is preferable that an interval between the substrate on which the electron-emitting devices are arranged and the light-emitting substrate be held to 1 mm to 10 mm and a voltage of 10 kV to 30 kV be applied between both the substrates (typically, between the anode electrode and each of the electron-emitting devices).
When a high voltage is applied at such a narrow interval, for example, it is necessary to suppress the occurrence of undesirable discharge around the anode electrode. Therefore, there have been proposed that an electroconductive film to which a potential lower than a potential applied to the anode electrode is applied is located so as to surround the anode electrode (see JP 2001-250494 A, JP 2002-100313 A, JP 2002-150979 A, JP 2003-331760 A, and JP 10-097835 A).
Of those proposals, there is a proposal to locate a resistor film between the anode electrode and the electroconductive film in order to stabilize a voltage between the anode electrode and the electroconductive film located so as to surround the anode electrode.
There have been proposed the anode electrode is composed of a plurality of electroconductive films, for example, in order to suppress the occurrence of discharge between the anode electrode and each of the electron-emitting devices (see JP 2002-175764 A and JP 2003-229074 A).
However, in the above-mentioned method, there is the case where undesirable discharge is caused between the anode electrode and the electroconductive film located around the lamination of a phosphor layer and the anode electrode or the case where the structure is complicated.
Therefore, an object of the present invention is to ensure a withstand voltage between the anode electrode and the electroconductive film located around the lamination of the phosphor layer and the anode electrode using a simpler structure.
The present invention has been made with a view to achieving the object, and provides a light-emitting substrate, comprising: a light-emitting member for emitting light by irradiation with an electron; a first electroconductive film stacked on the light-emitting member; a second electroconductive film which is distant from an outer periphery of the first electroconductive film and surrounds the outer periphery of the first electroconductive film; and a dielectric film for covering an end portion of the second electroconductive film which is opposed to the outer periphery of the first electroconductive film.
Further, the present invention has the following features: the second electroconductive film is an electroconductive film having a closed ring structure; a light absorbing layer which is located on the light-emitting substrate and has a plurality of openings, wherein the light-emitting member is located corresponding to the plurality of openings, and the light-emitting member and the light absorbing layer are covered with the first electroconductive film; an end portion of the first electroconductive film which is opposed to the second electroconductive film is covered with the dielectric film; a resistance value of the dielectric film is equal to or larger than 108 Ωm; the dielectric film contains a low-melting point glass or polyamide; the first electroconductive film comprises a plurality of electroconductive films which are connected in parallel through resistors; all around of the end of the second electroconductive film which is opposed to the first electroconductive film is covered with a dielectric film; a thickness of the end of the second electroconductive film which is opposed to the outer periphery of the first electroconductive film is smaller than an average film thickness of the second electroconductive film; the second electroconductive film comprises a plurality of electroconductive films which are stacked, and the end of the second electroconductive film which is opposed to the outer periphery of the first electroconductive film is formed in a stepped shape.
In addition, the present invention provides an image display apparatus, comprising: a light-emitting substrate; and a rear plate on which an electron-emitting device is located, wherein the light-emitting substrate comprises the above described light-emitting substrate, and a potential to be applied to the second electroconductive film is lower than a potential to be applied to the first electroconductive film.
Furthermore, the image display apparatus of the present invention has the following characteristics: when a length of the dielectric film covering the second electroconductive film from the end of the second electroconductive film which is opposed to the outer periphery of the first electroconductive film in a direction distant from the first electroconductive film is given by L [μm] and an average interval between the light-emitting substrate and the rear plate is given by d [μm],
L≧0.025×d+15
is satisfied; a spacer between the light-emitting substrate and the rear plate, wherein the spacer is located across the first electroconductive film and the second electroconductive film; the dielectric film is located outside a region between the spacer and the second electroconductive film; an electron capture structure for capturing an electron, which is located between the second electroconductive film and the first electroconductive film.
In addition, the present invention provides an image display apparatus, comprising: a face plate including a light-emitting member for emitting light by irradiation with an electron, a first electroconductive film which is stacked on the light-emitting member and has substantially a quadrangular outer periphery, and a second electroconductive film which is opposed to four sides of the quadrangular outer periphery and located at a distance from the quadrangular outer periphery of the first electroconductive film; a rear plate on which an electron-emitting device is located; a power source for applying, to the second electroconductive film, a potential lower than a potential applied to the first electroconductive film; and a dielectric film for covering an end of the second electroconductive film which is opposed to each of the four sides of the quadrangular outer periphery of the first electroconductive film.
Further, the present invention provides an image display apparatus, comprising: a face plate including a light-emitting member for emitting light by irradiation with an electron, a first electroconductive film stacked on the light-emitting member, and a second electroconductive film which is distant from an outer periphery of the first electroconductive film; a rear plate on which an electron-emitting device is located; a power source for applying, to the second electroconductive film, a potential lower than a potential applied to the first electroconductive film; and a dielectric film for covering an end of the second electroconductive film which is opposed to the outer periphery of the first electroconductive film, wherein the outer periphery of the first electroconductive film is surrounded by an equipotential line which is produced based on a potential applied from the power source and passes through the second electroconductive film on the face plate.
Further the present invention provides an image display apparatus according to claim 11, wherein a difference between the potential applied to the first electroconductive film and a potential applied to the electron-emitting device is 5 kV to 30 kV and a difference between the potential applied to the second electroconductive film and the potential applied to the electron-emitting device is equal to or smaller than 1 kV.
Furthermore, the image display apparatus of the present invention has the following characteristics: a difference between the potential applied to the first electroconductive film and a potential applied to the electron-emitting device is 5 kV to 30 kV and a difference between the potential applied to the second electroconductive film and the potential applied to the electron-emitting device is equal to or smaller than 1 kV; a difference between the potential applied to the first electroconductive film and a potential applied to the electron-emitting device is 5 kV to 30 kV and a difference between the potential applied to the second electroconductive film and the potential applied to the electron-emitting device is equal to or smaller than 1 kV; a wiring connected with the first electroconductive film; and a power source connected with the wiring, wherein the wiring is led to an outside of the image display apparatus without crossing the second electroconductive film;
Furthermore, the present invention provides an information display and reproduction apparatus, comprising: a receiver for outputting at least one of video information, character information, and voice information which are included in a received broadcast signal; and an image display apparatus connected with the receiver, wherein the image display apparatus comprises the above described image display apparatus.
Hereinafter, embodiments of the present invention will be specifically described below with reference to
In
In
A light-emitting member 1201 including light-emitting regions (131, 132, and 133 (described later with reference to FIG. 10)), an anode electrode 1202 serving as a first electroconductive film, and a second electroconductive film 1204 are arranged on the face plate 1002. The light-emitting member is typically composed of a phosphor. The anode electrode 1202 and the light-emitting member 1201 are overlapped with each other. In order to be able to display the image with the aspect ratio of 4:3 or 16:9, the light-emitting member 1201 and the anode electrode 1202 whose outer peripheries each have substantially a quadrangular shape, particularly a rectangular shape are preferably used. Therefore, it is preferable that the outer periphery of the anode electrode 1202 have substantially a quadrangular shape.
In the example described here, the anode electrode 1202 is provided on the light-emitting member 1201, so it is composed of a thin electroconductive film. The anode electrode 1202 which is provided on the light-emitting member 1201 and located on the side closer to the electron-emitting devices 1101 than the light-emitting member 1201 corresponds to a so-called “metal back”.
The anode electrode (metal back) 1202 has, for example, a function of making the electrons, which is emitted from the electron-emitting devices 1101, pass through itself and of colliding electrons emitted from the electron-emitting devices 1101 with the light-emitting member 1201. The anode electrode (metal back) 1202 has also a function of reflecting light emitted from the phosphor to the rear plate side toward the face plate 1002 side. In order to realize the functions, an electroconductive film having a metallic luster, that is, a metallic film is preferably used for the metal back 1202. The electrons excite the light-emitting member 1201 through the metal back 1202, so a part of the energies thereof are lost by the metal back 1202. When the energy loss is to be reduced, it is preferable to use an aluminum film whose energy loss is small for the metal back. A filming process which is a known technique in a CRT field can be employed as a method of producing the metal back 1202 composed of the aluminum film. A film thickness of the aluminum film is 10 nm to 1 μm in practical use. However, the present invention is not limited to this range.
It is preferable that the metal back 1202 cover the light-emitting member 1201. Therefore, a lamination composed of the light-emitting member 1201 and the metal back 1202 is located on the face plate 1002.
In the present invention, a member corresponding to the anode electrode can be referred to as the “first electroconductive film”. In the above-mentioned example, the metal back 1202 becomes the “first electroconductive film”. In some cases, the first electroconductive film is located between the phosphor 1201 and the face plate 1002.
When discharge is caused between the first electroconductive film 1202 and the rear plate 1001 (electron-emitting devices 1101 and the wirings 1103 and 1102) opposed thereto, a large current corresponding to charges accumulated in a capacitance formed by the first electroconductive film 1202 and the rear plate 1001 flows therebetween, so that the image display apparatus suffers fatal damage. Note that the current increases in proportion to a display area of the image display apparatus. Therefore, it is preferable that the first electroconductive film (metal back 1202) be composed of a plurality of electroconductive films. In that case, the plurality of electroconductive films are connected in parallel through resistors, preferably. When an area of each of the electroconductive films composing the first electroconductive film is reduced, it is possible to lower a capacitance produced between each of the electroconductive films and the rear plate 1001. As a result, a discharge current can be decreased to reduce discharge damage to the image display apparatus.
In the present invention, the face plate 1002 including the phosphor 1201, the anode electrode (first electroconductive film) 1202, and the second electroconductive film 1204 is referred to as the “light-emitting substrate”.
A side wall 1003 is located between the face plate 1002 and the rear plate 1001. The face plate 1002, the rear plate 1001, and the side wall 1003 are airtightly bonded to one another and an inner space produced by the bonding is evacuated to produce the airtight container 100. The airtight container 100 is maintained at a reduced state (vacuum state). The airtight container 100 is preferably maintained at the degree of vacuum of preferably 10−7 Pa or more. The degree of vacuum of 10−7 Pa can be reduced according to, for example, the type of the used electron-emitting device.
In the example described here, as shown in
Although the light absorbing member (typically black member) 1203 is not necessarily provided, it is preferably provided to improve the quality of a display image. In the example shown in
In the present invention, the light absorbing member 1203 can be also made of an electroconductive material. In such a case, the potential of the light absorbing member 1203 is maintained to a potential substantially equal to the potential of the metal back 1202. Therefore, a combination of the metal back 1202 and the light absorbing member 1203 functions as the anode electrode. That is, the first electroconductive film corresponding to the anode electrode is composed of the metal back 1202 and the light absorbing member 1203. Of course, when the light absorbing member 1203 is made of an insulator, the member that functions as the anode electrode becomes the metal back 1202, so that the metal back 1202 becomes the first electroconductive film.
The metal back 1202 is a very thin film having a thickness less than 1 μm (typically, 50 nm to 400 nm). Therefore, it is preferable that the light absorbing member 1203 be made of the electroconductive material because the uniformity of the potential of the metal back 1202 can be maintained to a high degree over the entire surface of the metal back. In view of a forming method, the metal back 1202 is hard to specify the shape of a peripheral portion thereof in some cases. Therefore, the light absorbing member 1203 which can be formed using a photolithography method or the like is made of the electroconductive material, so that the end shape of the anode electrode can be controlled/specified with high precision. As a result, it is possible to improve the controllability of an electric field within an image display region of the airtight container 100 and the reproducibility of manufacturing an image display apparatus. When the light absorbing member 1203 is to be made of an electroconductive material, electroconductive paste containing a metallic particle such as silver and low-melting glass, carbon black, or the like can be used as the material. In order to improve the function as the light absorbing layer, black pigment is contained in the light absorbing member 1203 in some cases.
In the example shown in
In the image display apparatus according to the present invention, an anode voltage (Va) is applied from the power source 1006 to the first electroconductive film (anode electrode) through the high voltage terminal 1005 (see
In one embodiment of the present invention, in order to suppress discharge in a region outside the first electroconductive film, the second electroconductive film 1204 is located so as to surround the outer periphery (circumference) of the first electroconductive film (see
A potential of the second electroconductive film 1204 is set to be closer to a surface potential of the rear plate 1001 than the potential of the anode electrode (anode voltage). That is, the voltage applied to the second electroconductive film 1204 is set to be lower than the anode voltage. More preferably, when the image display apparatus is driven, the potential applied to the electron-emitting device 1101 and the potential applied to the second electroconductive film 1204 are set such that a difference therebetween becomes 1 kV or less. The potential of the second electroconductive film 1204 may be typically within a range of a voltage applied when the electron-emitting device is driven (typically −50 V to +50 V). It is more preferable to specify the potential of the second electroconductive film 1204 to a GND potential because of convenience. When such setting is made, an electric field outside the second electroconductive film 1204 can be significantly weakened as compared with an electric field in a region caused by orthogonal projection to the first electroconductive film (image display region). Therefore, it is possible to prevent discharge resulting from discharge elements (such as foreign matters and protrusions) which are present outside the region included when the first electroconductive film (anode electrode) is orthogonally projected from the face plate 1002 side to the rear plate side 1001 side.
In the present invention, as shown in
In another structure of the second electroconductive film in the present invention, as shown in
In the case as shown in
In the present invention, when the second electroconductive film 1204 is composed of the plurality of electroconductive films as described above, the potentials applied to the plurality of electroconductive films are set to be substantially equal to each other.
As described with reference to
The second electroconductive film 1204 may be made of an electroconductive material. Electroconductive paste containing a metallic particle such as silver and low-melting glass, carbon black, or the like can be used as the electroconductive material. When the light absorbing member 1203 is made of the electroconductive material, the second electroconductive film 1204 can be formed using the same material as that of the light absorbing member 1203 simultaneously with the formation of the light absorbing member 1203. The second electroconductive film 1204 can be formed by a screen printing method or a photolithography method.
As described above, when the light absorbing member 1203 is made of the electroconductive material, the first electroconductive film (anode electrode) is composed of the metal back 1202 and the light absorbing member 1203. Then, when the area of the light absorbing member 1203 made of the electroconductive material is larger than the area of the metal back 1202 (the outer periphery of the metal back 1202 is located inside the outer periphery of the light absorbing member 1203), the second electroconductive film 1204 is formed so as to surround the outer periphery of the light absorbing member 1203 as shown in
In general, the insulating property of the glass substrate composing the face plate is high. Therefore, in view of suppressing discharge in the outer end of the first electroconductive film, as compared with the fact that the insulating property between the first electroconductive film (metal back) and the second electroconductive film 1204 is ensured by the light absorbing member 1203, it is preferable that the second electroconductive film 1204 be formed so as to surround the outer periphery of the light absorbing member 1203 at a distance from the outer periphery of the light absorbing member 1203 as shown in
When an electroconductive member corresponding to the anode electrode (electroconductive member to which the anode voltage is applied) is provided on the face plate 1002 in addition to the metal back 1202 and the light absorbing member 1203, a film including the electroconductive member corresponding to the anode electrode can be referred to as the “first electroconductive film” in the present invention.
In addition to the above-mentioned structures of the light-emitting substrate, for example, in order to improve the stability of the potential of the anode electrode, it is possible to use a structure in which a transparent electroconductive film made of ITO, tin oxide, or the like is provided between a layer (composed of the light-emitting member 1201 and the light absorbing member 1203) and the face plate (glass substrate) 1002. The transparent electroconductive film can be formed using a vapor phase process such as a sputtering method or a vacuum evaporation method or a liquid phase process using a fine particle dispersion solution, such as spray coating, spin coating, dipping, slit coating, or a sol-gel method. When the transparent electroconductive film instead of the metal back 1202 is formed as the anode electrode, the function as a light reflecting layer such as the metal back cannot be provided to the transparent electroconductive film. However, the structure is simplified, so a manufacturing cost can be reduced.
As described above, the anode electrode (“first electroconductive film”) in the present invention is not limited to only a combination of the metal back 1202 and the light absorbing member 1203.
In the present invention, the end portion of the second electroconductive film 1204 which is opposed to the first electroconductive film (anode electrode) is covered with a dielectric film 1205.
The dielectric film 1205 covering the end portion of the second electroconductive film 1204 will be described below in detail with reference to
In
The dielectric film 1205 in the present invention has a function of suppressing the occurrence of discharge (particularly surface discharge) between the first electroconductive film (anode electrode) and the second electroconductive film 1204 in a vacuum.
When the dielectric film 1205 is not provided (see
In other words, according to a phenomenon in which the field emission electron from the second electroconductive film 1204 travels to the first electroconductive film 1203 while causes multiple scattering in the surface (surface portion) of the dielectric 1002 (secondary electron emission avalanche), discharge may be led by the repetition of positive feedback in which the surface of the dielectric 1002 is positively charged to further increase an electric field strength near the second electroconductive film 1204. It is assumed that the amount of field emission electrons from the second electroconductive film 1204 is determined according to an electric field strength on the surface of the second electroconductive film 1204.
Dotted lines in
With respect to a factor of increasing the field multiplication factor, there is a planar shape of the end portion of the second electroconductive film 1204 which is opposed to the first electroconductive film 1203.
In the present invention, the end portion of the second electroconductive film 1204 which is opposed to the first electroconductive film (metal back 1202) is covered with the dielectric film 1205 to suppress the occurrence of discharge (particularly surface discharge) based on the following two reasons.
(1) When the electric field concentration region 1401 caused in the case where the dielectric film 1205 is not provided (see
(2) Even when an electron is emitted from a triple point 1402 (intersection point among the second electroconductive film 1204, the dielectric film 1205, and a vacuum) newly caused by the formation of the dielectric film 1205 for some reason, the electron trajectory continued until the emitted electron collides with the dielectric film 1205 is short (see
In order to develop the discharge suppression effects the material of the dielectric film 1205 is a dielectric material having large volume resistivity and a material having a high withstand voltage can be suitably used therefor.
It is possible to suitably use the dielectric film 1205 having volume resistivity of practically 108 Ωm or higher, more preferably 1012 Ωm or higher. When the volume resistivity of the dielectric film 1205 is 108 Ωm or higher, the emission of field electron from the electric field concentration region 1401 can be substantially prevented.
The electric field concentration region 1401 is caused in not only the tip of the end portion of the second electroconductive film which is opposed to the first electroconductive film (anode electrode) but also the vicinity of the tip. Therefore, as shown in
The inventors et al. of the present invention have conducted concentrated studies and thus found that a region in which an electric field strength becomes larger depends largely on a distance from the opposed substrate (rear plate 1001 in which the electron-emitting devices are arranged). Therefore, when a stacked layer width L (μm) (see
L≧0.025×H+15
a region having a large electric field strength in the end of the second electroconductive film which is opposed to the first electroconductive film (anode electrode) can be effectively covered with the dielectric film 1205. As a result, the field electron emission can be prevented to significantly suppress discharge.
It is necessary to set a thickness d of the dielectric film 1205 (see
For example, a screen printing method or an application method using a dispenser can be used as a method of applying the paste. It is preferable that the paste contain particularly low-melting glass. When the paste contains the low-melting glass, a backing temperature at the time of formation of the dielectric film 1205 can be reduced, so that the dielectric film 1205 can be easily formed. Another method involving forming the dielectric film 1205 may be a method of fixing or bonding a molded dielectric such as glass onto the second electroconductive film. A resin such as epoxy or polyimide may be used for the dielectric film 1205. In particular, the polyimide is preferable because of its high withstand voltage. A photolithography method is preferably used for the formation of the dielectric film 1205 because a shape of the dielectric film 1205 which is required for suppressing discharge can be obtained with high precision.
As shown in
As shown in
The end portion of the first electroconductive film (anode electrode) which is located on the second electroconductive film 1204 side is a portion concentratedly irradiated with electrons generated as a result of field emission from the second electroconductive film 1204 with a high possibility, so a local temperature is likely to increase. When the end portion of the first electroconductive film located on the second electroconductive film side is covered with the dielectric film 1205, electron irradiation portions can be dispersed to prevent an increase in temperature, thereby improving the withstand voltage.
As shown in
As shown in
Next, a method of connecting the first electroconductive film 1203 with the high voltage source 1006 for generating the anode voltage will be described with reference to
It is preferable that a wiring 1403 led from the first electroconductive film 1203 to the high voltage source 1006 be located in the airtight container 100 so as not to cross the second electroconductive film 1204. This reason is as follows. When a structure in which the wiring 1403 for connecting the high voltage source 1006 with the first electroconductive film (anode electrode) crosses the second electroconductive film 1204 is used because the airtight container 100 has a limited inner space size, it is likely to cause discharge between the wiring 1403 and the second electroconductive film 1204. A method of leading a wiring connected with the first electroconductive film 1203 to an outside of the airtight container 100 through a hole provided in the face plate 1002 (see
In the image display apparatus according to the present invention, an atmospheric pressure withstanding member which is called a spacer can be provided in addition to the structure shown in
In
For example, an adhesive or fixing member (1301) for fixing the spacer to the face plate and/or the rear plate is located in the end of the spacer 1004 in some cases. The adhesive or fixing member may become a discharge element. Because a sharp-edged portion or the like exists in the end of the spacer, the spacer is generally likely to cause discharge. Such structures (end of the spacer and the fixing member) are located in an outer region outside a region caused by orthogonal projection to the second electroconductive film. Here, the outer region is a region in which an electric field is weak. Therefore, it is possible to suppress discharge resulting from the structures (end of the spacer and the fixing member).
Assume that each of the anode electrode 1203 and the second electroconductive film 1204 which are shown in
When a potential on the surface of the spacer 1004 which is opposed to the second electroconductive film is largely different from a potential on the surface of the second electroconductive film which is opposed to the spacer, electric field concentration occurs between the spacer 1004 and the second electroconductive film 1204 to cause discharge in some cases. Therefore, it is preferable that the potential on the surface of the spacer 1004 which is opposed to the second electroconductive film 1204 be made substantially equal to the potential on the surface of the second electroconductive film 1204 which is opposed to the spacer 1004. When the spacer 1004 is in contact with the second electroconductive film 1204, the potential of the second electroconductive film 1204 can be supplied to the spacer 1004, so that the electric field concentration and the discharge resulting therefrom can be prevented.
When the surface of the second electroconductive film 1204 is completely covered with the dielectric film 1205, the spacer 1004 cannot be in electrical contact with the second electroconductive film 1204, so it is hard to supply the potential to the spacer. When a structure in which the dielectric film 1205 is not located in a region between the spacer 1004 and the second electroconductive film 1204 is used, the spacer 1004 and the second electroconductive film 1204 can be made in contact with each other. As a result, the potential on the surface of the spacer 1004 which is opposed to the second electroconductive film 1204 is made substantially equal to the potential on the surface of the second electroconductive film 1204 which is opposed to the spacer 1004 (see
In the present invention, when an electron capture structure 1206 which is a structure for capturing electrons is provided in addition to the dielectric film 1205 which is a feature of the present invention regardless of the presence or absence of the spacer 1004, a withstand voltage (surface withstand voltage) between the first electroconductive film and the second electroconductive film can be additionally improved.
The electron capture structure in the present invention will be described with reference to
The electron capture structure 1206 is the convex structure and each of side walls thereof has a surface nearly perpendicular to a plane joining the first electroconductive film 1203 to the second electroconductive film 1204 (surface of the face plate 1002). When the side walls exist, the possibility in which secondary electrons generated by irradiation of the side walls with electrons are immediately charged again to the side walls increases. Therefore, the electron trajectory can be shortened, so the secondary electron emission coefficient can be lowered to substantially 1 or less. Thus, it is possible to suppress the secondary electron emission avalanche between the first electroconductive film 1203 and the second electroconductive film 1204 (dielectric film 1205).
As shown in
As is also apparent from the above descriptions, it is necessary that a height of the electron capture structure 1206 in the present invention be set to be equal to or larger than a height in which electrons hardly climb over. The height is preferably set in a practical range of 1 μm to 100 μm.
As shown in
A method of obtaining the above-mentioned structure includes a method involving producing paste containing low-melting glass using a screen printing method or a photolithography method.
In particular, when the photolithography method is used, the above-mentioned overhung structure can be formed with high precision. Another producing method is a method involving the electron capture structure 1206 in advance using a dielectric material such as glass and fixing onto the face plate 1002 by an adhesive or the like.
Even when the electron capture structure 1206 is located in any position on the surface of the face plate 1002 between the anode electrode 1203 and the second electroconductive film 1204, a predetermined effect is obtained. Here, when it is assumed that the field emission electrons are emitted from the second electroconductive film 1204, it is preferable to locate the electron capture structure 1206 in a position closest to the second electroconductive film 1204. When the second electroconductive film 1204 is formed so as to surround the first electroconductive film 1203, the electron capture structure 1206 is preferably formed so as to surround the first electroconductive film 1203. That is, it is preferable to locate the electron capture structure 1206 along the end of the second electroconductive film 1204 which is located on the first electroconductive film side.
When the spacer 1004 is provided in the image display apparatus as described above, it is preferable to locate the electron capture structure 1206 between the spacer 1004 and the face plate 1002 as shown in
When the electron capture structure 1206 is thicker (higher) than the first electroconductive film 1203 and the second electroconductive film 1204, the spacer 1004 is hardly in contact with the first electroconductive film 1203 and the second electroconductive film 1204. Therefore, it is preferable that a height of the electron capture structure 1206 be substantially equal to or lower than heights of the first electroconductive film 1203 and the second electroconductive film 1204.
An information display and reproduction apparatus can be composed of the airtight container (image display apparatus) 100 according to the present invention as described with reference to
More specifically, a broadcast signal on a television broadcast is received by a receiving apparatus. The received signal is selected by a tuner. At least one of video information, character information, and voice information which are included in the selected signal is outputted to the airtight container (image display apparatus) 100 and displayed and/or reproduced. Therefore, an information display and reproduction apparatus such as a television can be constructed. Of course, when the broadcast signal is encoded, the information display and reproduction apparatus according to the present invention can include a decoder. The voice signal is outputted to separate voice reproducing means such as a speaker and reproduced in synchronization with the video information and the character information which are displayed on the airtight container (image display apparatus) 100.
For example, a method of outputting the video information or the character information to the airtight container (image display apparatus) 100 to display and/or reproduce it can be performed as follows.
It is possible to use a structure in which the interface can be connected with an image recording apparatus and an image outputting apparatus, for example, a printer, a digital video camera, a digital camera, a hard disk drive (HDD), and a digital video disk (DVD). Therefore, an image recorded in the image recording apparatus can be displayed on the display panel C11. In addition, it is possible to produce an information display and reproduction apparatus (or a television) capable of processing the image displayed on the display panel C11 if necessary and outputting the image to the image outputting apparatus.
The image display apparatus described here is an example of an image display apparatus to which the present invention can be applied. Therefore, various modifications can be made based on technical ideas of the present invention. The image display apparatus according to the present invention can be also used as a display apparatus for a television conference system, a computer, or the like.
The image display apparatus according to the present invention can be also used as, for example, an image forming apparatus such as an optical printer using a photosensitive drum or the like in addition to a display apparatus for television broadcasting and the display apparatus for a television conference system, a computer, or the like.
Hereinafter, specific embodiments of the present invention will be described in more detail.
This embodiment is an example of the light-emitting substrate shown in each of
First, soda lime glass is used for a transparent substrate which becomes the face plate 1002. The soda lime glass having a thickness of 2.8 mm is cleaned and the electroconductive black matrix 1203 is formed thereon in a grid shape by a photolithography method. The openings (phosphor regions) are arranged in the grid shape. In this embodiment, the black matrix 1203 composes a portion of the anode electrode.
Photosensitive carbon black is used as a material of the black matrix 1203 and formed at a thickness of 5 micrometers by a photolithography method. A pitch of a repeated pattern is set to 200 micrometers in a lateral direction (X-direction) and 600 micrometers in a longitudinal direction (Y-direction). A line width of the black matrix is set to 50 micrometers in the longitudinal direction (Y-direction) and 300 micrometers in the lateral direction (X-direction). The second electroconductive film 1204 is formed simultaneously with the formation of the black matrix 1203. The outer periphery of the black matrix 1203 is set in a range of 2 mm from the position in which the opening of the black matrix is provided to the outside. The second electroconductive film 1204 having a width of 2 mm is formed so as to surround the black matrix 1203 at a distance of 2 mm from the outer periphery of the black matrix 1203.
Next, the openings (phosphor regions 131, 132, and 133) of the black matrix are filled with fluorescent layers for respective colors based on the arrangement as shown in
Each of the fluorescent materials is a fluorescent material of P22 used in the field of CRT. The fluorescent materials includes a material for red (P22-RE3; Y2O2S:Eu3+), a material for blue (P22-B2; ZnS:Ag, Al), and a material for green (P22-GN4; ZnS:Cu, Al).
Next, the dielectric film 1205 is formed. Dielectric paste containing low-melting glass frit (including lead oxide) as a main ingredient is used for the dielectric film 1205 and formed at a thickness of 10 micrometers by a screen printing method.
The dielectric film 1205 is extended from the end of the second electroconductive film 1204 which is located on the black matrix side to the black matrix 1203 side by 500 micrometers. The dielectric film is located so as to cover the second electroconductive film 1204 in a range of 500 micrometers from the end of the second electroconductive film 1204 which is located on the black matrix side in a direction distant from the black matrix 1203. The dielectric film 1205 is formed so as to cover the entire end of the second electroconductive film 1204.
After the dielectric paste is applied so as to obtain the above-mentioned arrangement, baking is performed at 450° C. in an atmosphere. Volume resistivity of a test piece manufactured by baking the used dielectric paste is measured. As a result, the volume resistivity is about 1012 Ωm.
Next, a resin film is formed on the black matrix and the phosphor by a filming process which is known as a cathode ray tube manufacturing technique. After that, an aluminum evaporation film is deposited on the resin film. Finally, the resin film is removed by thermal decomposition to produce the metal back 1202 having a thickness of 100 nm on the black matrix 1203 and the phosphor. The outer periphery of the metal back 1202 is located inside the outer periphery of the black matrix 1203. In this embodiment, the black matrix 1203 and the metal back 1202 compose the anode electrode.
Next, a withstand voltage between the anode electrodes (1202 and 1203) and the second electroconductive film 1204 on the face plate 1002 (light-emitting substrate) manufactured thus is evaluated. As shown in
The face plate in this embodiment is evaluated with respect to a withstand voltage. As a result, when the anode voltage is 20 kV, discharge is not caused for a predetermined time or longer and a stable state is obtained. After that, when the voltage is gradually increased, discharge is caused at 31 kV.
Therefore, according to the light-emitting substrate in this embodiment, it is possible to apply a high voltage and obtain high reliability.
This embodiment shows an example using the electron capture structure 1206 shown in
The electron capture structure 1206 is formed as in the formation of the dielectric film 1205 in Embodiment 1. Dielectric paste containing low-melting glass frit (including lead oxide) as a main ingredient is used. A convex portion is formed from a dielectric having a width of 100 micrometers and a thickness of 10 micrometers.
The face plate manufactured thus is evaluated with respect to a withstand voltage by the same method as that in Embodiment 1. As a result, when the anode voltage is 20 kV, discharge is not caused for a predetermined time or longer and a stable state is obtained. After that, when the voltage is gradually increased, discharge is caused at 35 kV. Therefore, according to the light-emitting substrate in this embodiment, it is possible to apply a high voltage and obtain high reliability.
This embodiment shows an example in which the end of the anode electrode 1203 is covered with the dielectric film 1205 as shown in
The dielectric film 1205 stacked on the end of the anode electrode 1203 which is located on the second electroconductive film 1204 side is formed simultaneously with the formation of the dielectric film 1205 in Embodiment 1. Dielectric paste containing low-melting glass frit (including lead oxide) as a main ingredient is used. The dielectric film 1205 is formed by a screen printing method. The dielectric film 1205 formed on the anode electrode 1203 side is extended from the end of the anode electrode 1203 which is located on the second electroconductive film 1204 side to the second electroconductive film side by 500 micrometers. The dielectric film is stacked in a range of 500 micrometers from the end of the anode electrode 1203 which is located on the second electroconductive film 1204 side in a direction distant from the second electroconductive film. The thickness is set to 10 micrometers.
The face plate manufactured thus is evaluated with respect to a withstand voltage by the same method as that in Embodiment 1. As a result, when the anode voltage is 20 kV, discharge is not caused for a predetermined time or longer and a stable state is obtained. After that, when the voltage is gradually increased, discharge is caused at 32 kV. Therefore, according to the light-emitting substrate in this embodiment, it is possible to apply a high voltage and obtain high reliability.
In this embodiment, the airtight container 100 shown in
The face plate 1002 has the same structure as that in Embodiment 1 and is produced so as to obtain the same arrangement as that shown in
The face plate 1002 prepared thus is opposed to the rear plate 1001 on which the large number of surface conduction electron-emitting devices 1101 are arranged. The side wall 1003 is interposed between the face plate 1002 and the rear plate 1001. An interval between the face plate 1002 and the rear plate 1001 is set to 2 mm. A size of a vacuum container surrounded by the side wall 1003 is set to 70 mm×50 mm. The interval between the face plate 1002 and the rear plate 1001 is about 2 mm even when a member for regulating the interval is not provided. A method of producing the rear plate 1001 including the surface conduction electron-emitting devices 1101 is omitted here.
The side wall 1003 and the face plate 1002 are bonded to each other using a bonding material and the side wall 1003 and the rear plate 1001 are bonded to each other using the bonding material, thereby producing the airtight container 100 shown in
The airtight container 100 produced thus is connected with a driver circuit to construct an image display apparatus and withstand voltage evaluation is performed. In the withstand voltage evaluation, column directional wirings 1102 and row directional wirings 1103 on the rear plate 1001 are regulated to a GND potential and the second electroconductive film 1204 on the face plate 1002 is also regulated to the GND potential. With such a state, the anode electrode 1203 is connected with the high voltage source and the electron-emitting device is driven at 15 kV. The result confirms that discharge is not caused for a predetermined time or longer.
After that, drive signals are applied to the surface conduction electron-emitting devices through the column directional wirings 1102 and the row directional wirings 1103 and an image is displayed at the anode voltage of 12 kV. As a result, it is possible to stably display a preferable image having a high intensity and large contrast for a long period.
Here, when the column directional wirings 1102 and the row directional wirings 1103 are connected with the terminal for the GND potential again and the anode voltage to be applied to the anode is gradually increased, discharge is caused at 30 kV.
As described above, according to this embodiment, it is possible to obtain the image display apparatus to which a high voltage can be stably applied.
Only a length of the dielectric film 1205 covering the second electroconductive film 1204 (L described above) is set to be longer than that in this embodiment. Then, as in this embodiment, the anode voltage is gradually increased and a voltage at the time of start of discharge is measured. As a result, discharge is observed at 30 kV in any case regardless of the length of the dielectric film 1205 covering the second electroconductive film 1204.
In this embodiments the dielectric film 1205 is extended from the end of the second electroconductive film 1204 which is located on the black matrix side to the black matrix 1203 side by 100 micrometers. The dielectric film is located so as to cover the second electroconductive film 1204 in a range of 30 micrometers from the end of the second electroconductive film 1204 which is located on the black matrix side in a direction distant from the black matrix 1203. The dielectric film 1205 is formed so as to cover the entire end of the second electroconductive film 1204 which is located on the black matrix side. An image display apparatus is manufactured as in Embodiment 4 except for the size of the dielectric film 1205.
As in Embodiment 4, the column directional wirings 1102 and the row directional wirings 1103 of the manufactured image display apparatus are connected with a terminal for the GND potential and the withstand voltage evaluation is performed. The result confirms that discharge is not caused at 15 kV for a predetermined time or longer. When an image is displayed at the anode voltage of 12 kV, it is possible to stably display a preferable image having a high intensity and large contrast for a long period.
Here, when the column directional wirings 1102 and the row directional wirings 1103 are connected with the terminal for the GND potential again and the anode voltage is gradually increased, discharge is caused at 25 kV.
As described above, according to this embodiment, it is possible to obtain the image display apparatus to which a high voltage can be stably applied.
In this embodiment, the airtight container 100 in which the planar spacer 1004 is located between the face plate 1002 and the rear plate 1001 is produced and an image display apparatus is manufactured using the airtight container.
The face plate 1002 has the same structure as that in Embodiment 1 and is produced so as to obtain the same arrangement as that shown in
The face plate 1002 prepared thus is opposed to the rear plate 1001 on which the large number of surface conduction electron-emitting devices 1101 are arranged. The side wall 1003 is interposed between the face plate 1002 and the rear plate 1001. The spacer 1004 is located between the face plate 1002 and the rear plate 1001 such that an interval therebetween is set to 2 mm. A thickness of the spacer is set to 200 micrometers. The spacer 1004 is fixed to the rear plate 1001 by the bonding material 1301 (see
The airtight container 100 produced thus is connected with a driver circuit to construct an image display apparatus and withstand voltage evaluation is performed. In the withstand voltage evaluation, the column directional wirings 1102 and the row directional wirings 1103 on the rear plate 1001 are regulated to a GND potential and the second electroconductive film 1204 on the face plate 1002 is also regulated to the GND potential. With such a state, the anode electrode 1203 is connected with the high voltage source and the electron-emitting device is driven at 15 kV. The result confirms that discharge is not caused for a predetermined time or longer.
After that, drive signals are applied to the surface conduction electron-emitting devices through the column directional wirings 1102 and the row directional wirings 1103 and an image is displayed at the anode voltage of 12 kV. As a result, it is possible to stably display a preferable image having a high intensity and large contrast for a long period.
Here, when the column directional wirings 1102 and the row directional wirings 1103 are connected with the terminal for the GND potential again and the anode voltage is gradually increased, discharge is caused at 25 kV.
As described above, according to this embodiment, it is possible to obtain the image display apparatus to which a high voltage can be stably applied.
This embodiment shows an example of an image display apparatus manufactured using the face plate 1002 in which the second electroconductive film 1204 is composed of two kinds of electroconductive films (1207 and 1208) as shown in each of
According to a method of forming the second electroconductive film 1204, first, the electroconductive film 1207 made of aluminum is formed at a thickness of 100 nm by mask film formation. At this time, with respect to unevenness on a flat surface, it is determined that h/r at any position becomes 10 or less when a size of the convex shape as shown in
Next, the dielectric film 1205 is formed with a state in which a slit of 400 micrometers is provided in a region on which the spacer 1004 is located. Here, planar unevenness on a region in which the dielectric film 1205 is not provided and the second electroconductive film is exposed is formed to be substantially flat by the electroconductive film 1207. Therefore, it, can be expected that the electric field concentration be hardly caused in the region.
The same image display apparatus as that in Embodiment 6 is manufactured using the face plate 1002 produced thus. Then, as in Embodiment 4, the column directional wirings 1102 and the row directional wirings 1103 are connected with a terminal for the GND potential and the withstand voltage evaluation is performed. The result confirms that discharge is not caused at 15 kV for a predetermined time or longer. When an image is displayed at the anode voltage of 12 kV, it is possible to stably display a preferable image having a high intensity and large contrast for a long period.
Here, when the column directional wirings 1102 and the row directional wirings 1103 are connected with the terminal for the GND potential again and the anode voltage is gradually increased, discharge is caused at 25 kV.
As described above, according to this embodiment, it is possible to obtain the image display apparatus to which a high voltage can be stably applied.
A light-emitting substrate produced by the same method as that in Embodiment 1 except that the dielectric film 1205 is not provided is prepared (see
This application claims priority from Japanese Patent Application No. 2004-239528 filed on Aug. 19, 2004, which is hereby incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-239528 | Aug 2004 | JP | national |
This application is a division of U.S. application Ser. No. 11/201,139, filed Aug. 11, 2005.
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| Number | Date | Country | |
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| Child | 12436371 | US |
