Patent Grant
8022608
1. Field of the Invention
The present invention relates to an electron-emitting device, an electron-emitting apparatus, an electron source using the electron-emitting device and an image display device using the electron source. The present invention also relates to an information display/reproduction apparatus that receives a broadcast signal for a television broadcast and displays and reproduces video information, character information and audio information included in the broadcast signal.
2. Description of the Related Art
One type of electron-emitting apparatus employs an electron-emitting device of either a field emission type or a surface conduction type. As is further disclosed in patent documents 1 to 3 identified below, a process called an “activation” process is sometimes performed for the surface conduction electron-emitting device. The “activation” process is one for forming a carbon film in a gap between a pair of conductive films and on a conductive film near the gap.
An image display apparatus can be obtained by maintaining a vacuum space between a first substrate having an electron source and a second substrate having a light-emitting film. The electron source may be composed of a plurality of the electron-emitting devices arranged in rows and columns on the first substrate. The light-emitting film also may be composed of a phosphor and an anode electrode such as an electroconductive film.
[Patent Document 1]
Japanese Patent Laid-Open Publication No. 2000-251642
[Patent Document 2]
Japanese Patent Laid-Open Publication No. 2000-214643
[Patent Document 3]
Japanese Patent Laid-Open Publication No. 2000-231872
For recent image display devices, there is a need for images to be displayed more brightly and more stably for a long period of time. Thus, there is a demand for an electron-emitting device that provides a higher and more stable electron emission efficiency. The electron emission efficiency is the ratio of a current (hereinafter referred to as an emission current Ie) that is emitted to a vacuum to a current (hereinafter referred to as a device current If) that flows across a pair of conductive films when a voltage is applied thereto. That is, for the electron-emitting device, it is preferable that the device current If be as small as possible and that the emission current Ie be as large as possible. When a high electron emission efficiency can be stably maintained for an extended period of time, an image display device (e.g., a flat television) can be obtained that provides, at a low power consumption, bright, high quality images.
The present invention therefore provides an electron-emitting device that enables an electron source to have a high electron emission efficiency and a satisfactory electron emission characteristic for an extended time period, an electron source that uses the electron-emitting device, and an image display device.
To resolve the conventional problems, this invention provides an electron-emitting device comprising: a first conductive film having an end portion, and a second conductive film having an end portion being separated from the end portion of the first conductive film and facing the end portion of the first conductive film. The end portion of the second conductive film includes a first portion, a second portion and a third portion, and the first portion is located between the second and third portions. A thickness of the second conductive film at the first portion is smaller than the thickness of the second conductive film at the second and third portions. A thickness of the end portion of the first conductive film facing the first portion is smaller than the thickness of the second conductive film at the second and third portions.
For the electron-emitting device of the invention, the thickness of the end portion of the first conductive film facing the first portion is approximately equal to or greater than the thickness of the first portion of the second conductive film.
For the electron-emitting device of the invention, the first conductive film further has a fourth portion and a fifth portion. The end portion facing the first portion is arranged between the fourth and fifth portions, and a distance between the end portion facing the first portion and the second conductive film is smaller than distances between the fourth and fifth portions and the second conductive film.
For the electron-emitting device of the invention, when a distance between the first portion and the end portion of the first conductive film facing the first portion is defined as d, differences between the thickness of the second conductive film at the first portion and the thickness of the second conductive film at the second and the third portions are set equal to or greater than 2 d and equal to or less than 200 d.
For the electron-emitting device of the invention, when a distance between the first portion and the end portion of the first conductive film facing the first portion is defined as d, a distance between the second portion and the third portion is set equal to or greater than 2 d and equal to or smaller than 50 d.
For the electron-emitting device of the invention, when a distance (the shortest distance) between the first portion and the end portion facing the first portion is defined as d, thicknesses of the second conductive film at the second and third portions, in a direction in which the first portion and the end portion of the first conductive film oppose each other, are equal to or less than 200 d.
For the electron-emitting device of the invention, a distance between the first portion of the end portion of the first conductive film facing the first portion is equal to or greater than 1 nm and equal to or less than 10 nm. For the electron-emitting device of the invention, the first conductive film and the second conductive film preferably are carbon films.
For the electron-emitting device of the invention, the first and second conductive films are arranged on a surface of a substrate having a recessed portion located between the first and second conductive films.
Furthermore, the present invention provides, according to another aspect, an electron-emitting device having a first conductive film including an electron emission portion and a second conductive film including a portion facing the electron emission portion, arranged at an interval.
A thickness of the second conductive film at the portion facing the electron emission portion is equal to or not larger than a thickness of the first conductive film at the electron emission portion.
When electrons are emitted by applying a drive voltage Vf [V] between the first conductive film and the second conductive film so that a potential of the second conductive film is higher than a potential of the first conductive film, an equipotential line of 0.5 Vf [V], in a vicinity of the electron emission portion in a cross section extending across the electron emission portion and the portion facing the electron emission portion, is inclined toward the first conductive film.
The present invention also provides an electron source including a plurality of electron-emitting devices according to the invention, and provides an image display device comprising the electron source and a light-emitting member.
The present invention also provides an information display/reproduction apparatus that comprises at least a receiver, for outputting at least video information, character information or audio information included in a received broadcast signal, and the above described image display device, which is connected to the receiver.
According to another aspect of the present invention, an electron-emitting apparatus is provided, comprising an electron-emitting device including a first conductive film and a second conductive film arranged at an interval, on a surface of a substrate, and also comprising an anode electrode located at a distance H [m] from the surface of the substrate.
A voltage Va [V] is applied between the anode electrode and the first conductive film so that a potential of the anode electrode is higher than a potential of the first conductive film. A drive voltage Vf [V] is applied between the first conductive film and the second conductive film so that a potential of the second conductive film is higher than the potential of the first conductive film, to emit electrons from the first conductive film.
A thickness of a first portion of the second conductive film, which is located at a shortest distance d from a portion of the first conductive film from which electrons are emitted by applying the drive voltage Vf [V] to the electron-emitting device, is equal to or smaller than the thickness of the portion of the first conductive film from which the electrons are emitted. The shortest distance d is smaller than (Vf×H)/(Π×Va), and the second conductive film has a second portion and a third portion, between which the first portion is arranged. The second portion and the third portion of the second conductive film are thicker than the first portion.
According to this invention, an electron-emitting device having an improved electron emission efficiency and an electron-emitting apparatus that uses such an electron-emitting device are provided. As a result, an image display device that maintains superior image display quality for an extended period of time and an information display/reproduction apparatus that uses this display device can be provided.
Furthermore, according to the electron-emitting apparatus of the invention, since the equipotential line, in the vicinity of the electron-emitting portion of the first conductive film, that corresponds to half (0.5 Vf) of the voltage (Vf) applied between the first and second conductive films is inclined toward the first conductive film, the trajectory of electrons emitted from the electron-emitting portion is changed. As a result, the emission current Ie that reaches the anode is increased (the electron emission efficiency is increased). For example, since the second portion and the third portion are higher than a portion of the first conductive film end which faces the first portion, the equipotential line corresponding to half of the applied voltage (Vf) may be inclined toward the first conductive film by an electric field caused by shapes of the second and third portions. As a result, the emission current Ie reaching the anode is increased (efficiency is increased).
Further features and advantages of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
One embodiment of the present invention will now be described. First, an example basic structure for an electron-emitting device according to the present invention will be explained while referring to
In
Therefore, the distance d between the first portion 33 (corresponding to the portion B) of the second conductive film 21b and the opposite portion A of the first conductive film 21a is smaller than the distance between the fourth portion 37 of the first conductive film 21a and the second portion 35 of the second conductive film 21b, and is also smaller than the distance between the fifth portion 38 of the first conductive film 21a and the third portion 36 of the second conductive film 21b.
The thickness of the first portion 33 (corresponding to the portion B) of the second conductive film 21b is smaller than the thicknesses of the second portion 35 and the third portion 36 of the second conductive film 21b. Since the second portion 35 and the third portion 36 of the second conductive film 21b are farther from the surface of the substrate 1, unlike the other portions of the second conductive film 21b, these portions can also be called “projected portions” or “prominent portions”.
Because of this structure, there is a difference “h” (or the height “h” of the projected portions) between the heights of each of the second and the third portions 35 and 36 of the second conductive film 21b, measured from the surface of the substrate 1, relative to the height of the first portion 33 (portion B), measured from the surface of the substrate 1.
At least two “projected portions” 35 and 36 are present on the second conductive film 21b, and there is a gap “w” between them. The gap “w” can practically be defined as a distance between the points (tops or apexes or summits) of the projected portions 35 and 36 that are farthest from the surface of the substrate 1.
It is preferable that practically the gap w between the projected portions be set equal to or greater than 2 d and equal to or smaller than 50 d, because within this range, a high emission current Ie and a high electron emission efficiency can be obtained.
The height “h” of the projected portions 35 and 36 can actually be defined as a value obtained by subtracting the shortest distance between the portion B and the surface of the substrate 1 from the shortest distance between the surface of the substrate 1 and the farthest point (the top or apex or summit) of one of the projected portions 35 and 36. It is preferable that the height h of the “projected portion” 35 or 36 effectively be set equal to or greater than 2 d and equal to or smaller than 200 d, because within this range a high emission current Ie and a high electron emission efficiency can be obtained. When the heights of the projected portions 35 and 36 differ, the above-described condition need only be established for the lowest projected portion.
As will be described later, the electron-emitting device of the invention may further include: a first electrode 4a connected to the first conductive film 21a, for supplying a potential to the first conductive film 21a; and a second electrode 4b connected to the second conductive film 21b, for supplying a potential to the second conductive film 21b.
Furthermore, for the electron-emitting device of the invention, part of the outer edge (or border) of the gap 8 can be regarded as being formed by the portion A and the portion B. The fourth portion 37 and the fifth portion 38 of the first conductive film 21a and the second portion 35 and the third portion 36 of the second conductive film 21b may be also regarded as a part of the outer edge (or border) of the gap 8.
An explanation will now be given for an operation for driving the electron-emitting device of this invention. For example, as is shown in a schematic diagram in
The effective field strength used for driving (electron emission) the electron-emitting device of the invention (the field strength applied between the first conductive film 21a and the second conductive film 21b) is preferably equal to or greater than 1×109 V/m and less than 2×1010 V/m. When the field strength falls below this range, the number of electrons tunneled is tremendously reduced, and when the field strength rises beyond this range, the first conductive film 21a and/or the second conductive film 21b may be deformed by the strong electric field, and unstable electron emission tends to occur.
Compared with the electron-emitting device in
In
In
In lieu of an explanation that will be given later, in the cross section in
An arrow indicated by a broken line in
Since the conductive films 21a and 21b are very thin, the “thickness of the second conductive film 21b present in the direction in which electrons are emitted” can be substantially identified by “depths” D, as denoted in
When the “depth” is not constant in heights of the “projected portion”, for example, when the “depths” of the “projected portions” 35 and 36 are reduced as these portions are more distant from the surface of the substrate 1, the “thickness of the second conductive film 21b present in the direction in which electrons are emitted” or the “depths” of the “projected portions” 35 and 36 can further be identified by “the length of the second conductive film 21b in the direction in which the first and the second conductive films 21a and 21b face each other on the surface of the substrate 1. This length is, for example, a third plane that is parallel to the surface of the substrate 1 and is positioned between a first plane, which is parallel to the surface of the substrate 1 and which includes the apex (top or summit or proximal end) of either the “projected portion” 35 or 36 farthest from the surface of the substrate 1, and a second plane, which is parallel to the surface of the substrate 1 and which includes the portion A of the first conductive film 21a. When the heights of the projected portions 35 and 36 differ, the first plane need only includes the lower projected portion apex.
It is preferable that the third plane be positioned midway between the first plane and the second plane (the same distance from the first plane as from the second plane). Further, as will be described later, when the electron-emitting device of the invention includes a first electrode 4a and a second electrode 4b (or a first auxiliary electrode 2 and a second auxiliary electrode 3), the “direction in which the first conductive film 21a and the second conductive film 21b face each other on the surface of the substrate 1” can be replaced with a direction in which the first electrode 4a and the second electrode 4b face each other (or the first auxiliary electrode 2 and the second auxiliary electrode 3 face each other).
When the distance between the portions A and B in
In
Furthermore,
The equipotential lines in
In the electron-emitting apparatus shown in
However, for both the electron-emitting apparatus and the image display device that will be described later, the strength of the electric field generated between the anode electrode 44 and the electron-emitting device is typically equal to or less than 1/10 the strength of the electric field generated between the first and the second conductive films 21a and 21b (applied to the gap 8). Accordingly, an electric field in the vicinity of the electron-emitting portion (the vicinity of the gap 8) is adversely affected little by the potential of the anode electrode 44. Therefore, the equipotential lines in the vicinity of the gap 8 having basically the same forms as in
Furthermore,
For the electron-emitting device of this invention, as is shown in
On the other hand, for an electron-emitting device wherein the second portion 35 and the third portion 36 described above are not present, as is shown in
Furthermore, for the electron-emitting device of the invention, as is described above, at the portions (the portion A and the portion B in
With this arrangement, the probability that the electrons emitted (tunneled electrons) from a portion where the electrons must be emitted (corresponding to the portion A in
To drive the electron-emitting device of this invention, as shown in
Assume that H [m] denotes the distance between the substrate 1 in
Referring to
The substrate 1 can be, for example, a silica glass plate, a soda lime glass plate, or a soda lime glass plate whereon oxide silicon (specifically SiO2) is laminated using a well-known film deposition method, such as a sputtering method. As is described above, in this invention, a material containing silicon oxide (specifically SiO2) is preferably employed for the substrate.
Both the first conductive film 21a and the second conductive film 21b may be formed of an electroconductive film comprising an electroconductive material such as Ni, Au, PdO, Pd, Pt or carbon. It is especially preferable that these films (21a, 21b) contain carbon (made of carbon films) because a large number of electrons can be emitted and greater stability can be maintained over time. Further, it is preferable, as a practical range, that the films (21a, 21b) contain equal to or greater than 70 atm % of carbon.
Further, as will be described later while referring to
In addition, as will be described later while referring to
A modification of the electron-emitting device of this invention will now be explained while referring to
According to the structure shown in
In
The first electrode 4a and the second electrode 4b are opposite each other, in a direction parallel to the surface of the substrate 1, and are completely separated by an intervening second gap 7, which serves as a boundary. However, in some embodiments, small areas of the electrodes 4a and 4b may be connected. When one conductive film is divided to form the first and the second electrodes 4a and 4b, as in a “forming process” that will be described later, the second gap 7 may also be described as “a second gap 7 formed in part of the conductive film”. That is, it is ideal for the two films (4a, 4b) to be completely separated; however, so long as a satisfactory electron emission characteristic is obtained, the first and the second electrodes (4a, 4b) may be connected in a minute area. Further, wiring and auxiliary electrodes (not shown in
It is preferable that, as is shown in
A selected conductive material can be employed for the first and the second electrodes 4a and 4b. For example, a metal such as Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu, Pd, or an alloy of them, a transparent conductor such as In2O3—SnO2, or a semiconductor such as polysilicon may be used for the conductive material.
It is especially preferable that the electron-emitting device of this invention has a structure (or structures) schematically shown in
Various methods for manufacturing the electron-emitting device of the invention can be employed. For example, the following steps, (1) to (5), may be employed for the manufacturing process.
An example manufacturing method will now be described while referring to
(Step 1)
The substrate 1 is appropriately cleaned using a detergent, pure water and an organic solvent, and then, an auxiliary electrode material is deposited on the substrate 1 using the vacuum evaporation method or the sputtering method, etc. Thereafter, the first auxiliary electrode 2 and the second auxiliary electrode 3 are formed using the photolithography technique, etc (
The auxiliary electrodes 2 and 3 must be designed, and the distance between them and their lengths and shapes are appropriately determined, in accordance with the application of the electron-emitting device. For example, when an electron-emitting device is to be employed in a display device for a television set, which will be described later, the resolution to be used must be taken into account when the auxiliary electrodes 2 and 3 are designed, and since the pixel size for a high definition (HD) television is small, a high resolution is required. Therefore, in order to obtain sufficient brightness with an electron-emitting device having a limited size, the auxiliary electrodes 2 and 3 must be so designed that a satisfactory emission current Ie can be obtained.
In this example, the practical distance between the auxiliary electrodes 2 and 3 is equal to or longer than 5 μm and equal to or shorter than 100 μm, and the practical thickness of the auxiliary electrodes 2 and 3 is equal to or greater than 10 nm and equal to or smaller than 10 μm.
(Step 2)
A conductive film 4 is formed to connect the first and the second auxiliary electrodes 2 and 3 (
The material for the conductive film 4 can be, for example, a metal such as Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu or Pd, or an alloy or metal oxide of them, a transparent conductor such as In2O3—SnO2, or a semiconductor such as a polysilicon semiconductor.
The organic metal solution can be a solution of an organic metal compound that contains, as the main element, a metal such as Pd, Ni, Au or Pt that is used as the conductive film 4. The conductive film 4 in this case is deposited by applying a coating of the organic metal solution; however, the means used to deposit the conductive film 4 is not limited to this method, and the vacuum evaporation method, the sputtering method, the CVD method, the dispersing coating method, the dipping method, the spinner method or the ink jet method, etc, also can be employed.
When a “forming process” is to be performed at the succeeding step, it is preferable that the Rs (sheet resistance) of the conductive film 4 be set within the range 102 Ω/□ to 107 Ω/□. It should be noted that Rs is a value obtained when a resistance R is measured as R=Rs(l/w) in the longitudinal direction of the film, wherein t is the thickness, w is the width and l is the length of the film. When the resistivity is defined as p, Rs=p/t is established. The thickness of the conductive film 4 representing the above described sheet resistance, suitable for practical use, is 5 nm to 50 nm.
(Step 3)
Sequentially, the so-called “forming” process is performed by applying a voltage between the auxiliary electrodes 2 and 3. The second gap 7 is formed in part of the conductive film 4 by the application of the voltage. As a result, the first electrode 4a and the second electrode 4b are formed opposite each other, transversely across the surface of the substrate 1 (
The electrical process that follows the forming process can be performed, for example, by placing the substrate 1 in the measurement/evaluation apparatus shown in
The “forming process” can be performed either by repetitively applying a pulse voltage having a constant pulse height, or by applying a pulse voltage while gradually increasing the pulse height.
An example pulse wave having a constant pulse height is shown in
In
Whether the “forming” process should be terminated can be determined in the following manner. During the halt period (interval) for the pulse voltage, the current (device current If) flowing across the auxiliary electrodes 2 and 3 is measured by applying a voltage (e.g., the pulse voltage of about 0.1 V) that does not adversely affect the conductive film 4, and the resistance value of the conductive film 4 described above is obtained. When the resistance is equal to or higher than, for example, 1000 times the resistance before the “forming” process, the “forming” process can be terminated.
The pulse height, the pulse width, the pulse interval (halt time) and the pulse period are not limited to the above described values, and appropriate values can be selected in accordance with the resistance of the electron-emitting device, so as to obtain an appropriate gap 7.
In this example, the electrodes 4a and 4b are obtained by performing the “forming process” on the conductive film. However, in this invention, a well-known method, such as the photolithography method, can also be employed to form the first and the second electrodes 4a and 4b. Further, when the first carbon film 21a and the second carbon film 21b are to be formed through the “activation step”, which will be described later, preferably the “forming process” is employed because it is preferable that the gap 7 between the first and the second electrodes 4a and 4b be narrow. Instead of the “forming process”, the FIB (focused ion beam) irradiation method or the electron beam lithography method can also be employed to form the narrow gap 7 in the conductive film 4. Further, so long as various methods described above are employed to obtain a gap between the first auxiliary electrode 2 and the second auxiliary electrode 3, the first electrode 4a and the second electrode 4b are not always required. However, in order to manufacture the electron-emitting device of the invention at a low cost, it is preferable that the auxiliary electrodes 2 and 3 be employed as electrodes for stably supplying a potential to the carbon films that are formed during the “activation” process, which will be described later, and that the first electrodes 4a and the second electrodes 4b be employed as electrodes for stably and quickly depositing carbon films (21a, 21b) in the initial stage of the “activation process”.
(Step 4)
The “activation” process is now performed. During the “activation” process, a carbon containing gas is introduced into the vacuum apparatus shown in
An organic material gas may be used as the carbon containing gas, such as alkane, alkene or alkyne aliphatic hydrocarbon, aromatic hydrocarbon, alcohol, aldehyde, ketone, amine, or an organic acid such as phenol, carboxylic acid or sulfonic acid. Specifically, the following organic materials can be employed: saturated hydrocarbon, such as methane, ethane or propane, expressed as CnH2n+2; unsaturated hydrocarbon, such as ethylene or propylene, expressed, for example, as a composition formula of CnH2n; benzene; toluene; methanol; ethanal; formaldehyde; acetaldehyde; acetone; methyl ethyl ketone; methylamine; phenol; formic acid; acetic acid; and propionic acid.
It is preferable that the carbon containing gas be introduced into the vacuum apparatus after the pressure therein has been reduced to 10−6 Pa. Since the preferable partial pressure for the carbon containing gas differs depending on the form of the electron-emitting device, the shape of the vacuum apparatus and the type of carbon containing gas that is employed, the partial pressure is appropriately designated.
The pulse wave shown in
When a voltage having a waveform shown in
On the other hand, when a voltage having an asymmetrical waveform, as schematically shown in
Furthermore, when the “activation” process is performed by employing either waveform shown in
When the temperature of the substrate 1 is increased under a condition wherein SiO2 (the material of the substrate) is present near carbon, Si is consumed.
SiO2+C→SiO↑+CO↑
It is assumed that Si in the substrate is consumed because the above reaction has occurred, and that the surface of the substrate 1 is scraped (recessed portion is formed).
With the substrate-deformed portion (recessed portion) 22, the creeping distance between the first carbon film 21a and the second carbon film 21b can be increased. Thus, it is possible to suppress the discharge breakdown phenomenon that is assumed to occur due to a strong electric field applied between the first and the second carbon films 21a and 21b when the electron-emitting device is driven, and it is also possible to suppress the occurrence of an excessive device current If.
Carbon contained in the first carbon film 21a and the second carbon film 21b according to the invention will now be described. It is preferred that the carbon contained in the first and the second carbon films 21a and 21b be graphite like carbon. Graphite like carbon in the invention includes a complete graphite crystal structure (so-called HOPG), a somewhat incomplete crystal structure (PG) having a grain size of about 20 nm, a more incomplete crystal structure (GC) having a grain size of about 2 nm, and amorphous carbon (amorphous carbon and/or a mixture of amorphous carbon and the micro crystals of the graphite). That is, the graphite like carbon can be satisfactorily employed even when a layer, such as a grain boundary, between graphite grains is disturbed.
(Step 5)
The process is performed to change the shapes of the first carbon film 21a and the second carbon film 21b to those in
Specifically, a method employing an AFM (Atomic Force Microscope), shown in
The process that uses the AFM is performed as follows. When through the “activation” process the second carbon film 21b is formed thicker than the first carbon film 21a (a bipolar pulse voltage for which a voltage value or a pulse width is asymmetrical, on the positive side and on the negative side, is repetitively applied), first, the probe 90 of the AFM is positioned on the second carbon film 21b (
The end of the second carbon film 21b (the second carbon film end) can be scraped in the AFM contact mode (the contact pressure is controlled by a voltage). Using this method, the first portion B, and the second portion 35 and the third portion 36 described while referring to
Through the above-described steps, the electron-emitting device of the invention shown in
Specifically, extra carbon and organic substances are discharged into a vacuum container. It is preferable that organic substances in the vacuum container be removed, to the extent possible, until the partial pressure of organic substances is equal to or lower than 1.3×10−8 Pa. Furthermore, the pressure throughout the vacuum container, including other gases, is preferably equal to or lower than 1.3×10−6 Pa, and more preferably equal to or lower than 1.3×10−7 Pa. A vacuum pump apparatus for exhausting the vacuum container can be specifically an adsorption pump or an ion pump that does not use oil, so that there is no chance for oil to adversely affect the electron emission characteristic of the electron-emitting device. Furthermore, it is preferable that the entire vacuum container be heated, so that organic molecules attached to the inner walls of the vacuum container and the electron-emitting device can be easily discharged. The heating should be performed as long as possible at a temperature of 150° C. to 350° C., but preferably equal to or higher than 200° C. However, the heating conditions are not limited to these.
It is preferable that after the “stabilization” process has been terminated, the same atmosphere be maintained when the electron-emitting device is to be driven. However, so long as the organic substances are appropriately removed, the satisfactorily stable characteristic of the electron-emitting device can be maintained even when the pressure is slightly increased.
When the electron-emitting device is driven in such a vacuum atmosphere, the deposition of new carbon or a new carbon compound can be prevented. As a result, the shape of the electron-emitting device of the invention can be maintained, and the device current If and the emission current Ie accordingly stabilized.
The basic characteristic of the electron-emitting device of the invention will now be described while referring to
In
First, when a device voltage at a specific level or higher (called a threshold voltage; Vth in
Second, since the emission current Ie depends on the device voltage Vf, the emission current Ie can be controlled by using the device voltage Vf.
Third, the emission charges captured by the anode electrode 44 (
By using the above-described properties of the electron-emitting device, the electron emission characteristic can be easily controlled in consonance with an input signal. Further, since the electron-emitting device of the invention has a stable and high-luminance electron emission characteristic, the electron-emission device can be usable in various fields.
An example of another aspect of the invention will now be explained.
An electron source or an image display device, such as a television set, can be constituted, for example, by arranging a plurality of the electron-emitting devices of the invention on a substrate.
The array of the electron-emitting devices arranged on the substrate can, for example, be a “ladder-like” array or a “matrix” array as shown in
This matrix array will now be described in detail.
According to the above described three basic properties of the electron-emitting device of the invention, the electrons to be emitted can be controlled in accordance with the height and width of the pulse voltage that is applied between the first conductive film 21a and the second conductive film 21b. When the voltage to be applied is lower than the threshold value (Vth), electrons are not substantially emitted. According to these properties, when multiple electron-emitting devices are arranged, and when the pulse voltage is appropriately applied to the individual electron-emitting devices, the number of electrons to be emitted by a selected electron-emitting device can be controlled in consonance with an input signal.
While referring to
On an insulating substrate 71, m X-directional wirings 72, Dx1 to Dxm, are formed using the vacuum evaporation method, the printing method or the sputtering method, etc. The X-directional wirings 72 are made of metal, and the material, the thickness and the line width therefor are properly designated so that they supply an almost uniform voltage to multiple electron-emitting devices 74. Y-directional wirings 73 Dy1 to Dyn are formed of the same material using the same method as that used for the X-directional wirings 72. Between the m X-directional wirings 72 and the n Y-directional wirings 73, an insulating layer (not shown) of SiO2, for example, is formed using the vacuum evaporation method, the printing method or the sputtering method.
The individual electron-emitting devices 74 are connected to one of the X-directional wirings 72 and to one of the Y-directional wirings 73.
Further, scan signal application means (not shown), for transmitting a scan signal, is electrically connected to the X-directional wirings 72. Whereas, demodulation signal generation means (not shown) is electrically connected to the Y-directional wirings 73 so as to apply, in synchronization with the scan signal, a modulation signal for modulating electrons emitted by a selected electron-emitting device. These means will be described later in detail. The drive voltage Vf applied to the individual electron-emitting device 74 is supplied as a voltage difference between the scan signal to be applied and the modulation signal.
While referring to
In
When the envelope 88 has been sealed in the air or in the nitrogen atmosphere, thereafter, the air in the envelope 88 is evacuated through an exhaust pipe (not shown) until the internal pressure reaches a desired vacuum level (e.g., about 1.3×10−5 Pa) and the exhaust pipe is closed. As a result, the envelope 88, which maintains an internal vacuum, can be obtained. Further, when the envelope 88 is sealed in a vacuum, the sealing of the envelope can be performed at the same time, without the exhaust pipe being required, and the envelope 88, which maintains an internal vacuum, can be easily fabricated.
In addition, before or after the envelope 88 is sealed, a getter (not shown) located inside the envelope 88 may be activated. As is described above, before or after the envelope 88 is to be sealed in a vacuum, the getter (not shown) located inside the envelope 88 is activated. As a result, the internal vacuum level of the envelope 88 can be maintained after being closed.
The envelope 88 can be constituted by the face plate 86, the support frame 82 and the rear plate 81. However, since the rear plate 81 is provided mainly for reinforcing the strength of the substrate 71, the rear plate 81 is not required so long as the substrate 71 has sufficient strength. In this case, the support frame 82 is directly sealed to the substrate 71, and the envelope 88 is constituted by the face plate 86, the support frame 82 and the substrate 71.
Further, a support member (not shown) called a spacer may be arranged between the face plate 86 and the rear plate 81 (substrate 71), so that an envelope 88 having an appropriate strength, relative to the air pressure, can be provided.
The conductive film 85 (
The conductive film 85 is preferably an aluminum film. After the fluorescent film 84 has been deposited, a smoothing process (generally called “filming”) is performed for the surface of the fluorescent film 84, and thereafter, Al is deposited by vacuum evaporation to obtain the conductive film 85.
A transparent electrode (not shown) made, for example, of ITO may be formed between the fluorescent film 84 and the plate 83 to increase the conductivity of the fluorescent film 84.
A voltage is applied to the individual electron-emitting devices in the envelope 88 via terminals Dox1 to Doxm and Doy1 to Doyn, which are connected to the X-directional wirings 72 and the Y-directional wirings 73. With this arrangement, electrons can be emitted by a desired electron-emitting device. At this time, a voltage equal to or higher than 5 kV and equal to or lower than 30 kV, but preferably equal to or higher than 10 kV and equal to or lower than 20 kV, is applied to the metal back 85 via a high voltage terminal 87. The distance between the face plate 86 and the substrate 71 is preferably set equal to or longer than 1 mm and equal to or shorter than 3 mm. With this structure, electrons emitted by a selected electron-emitting device are transmitted through the metal back, and collide with the fluorescent film 84. Then, since the phosphor(s) 92 become luminous, an image can be displayed.
For this arrangement, the details, such as the materials of the members, are not limited to those described above, and can be appropriately changed in accordance with predetermined design/operating criteria the intended purposes.
Furthermore, an information display/reproduction apparatus can be provided by employing the envelope (image display device) 88 of this invention, which was explained while referring to
Specifically, an information display/reproduction apparatus comprises: a receiver, for receiving a broadcast signal, such as a television broadcast signal, etc; and a tuner, for selecting a received signal, whereby, at least video information, character information or audio information included in the selected signal is output to the envelope (image display device) 88 for a display and/or for reproducing images and/or sound. Of course, when a broadcast signal is encoded, the information display/reproduction apparatus of the invention can also include a decoder. An audio signal is output to separately provide audio reproduction means, such as a loudspeaker, so that sounds are released in synchronization with the video information and the character information reproduced in the envelope (image display device) 88.
The following method, for example, can be employed to output video information or character information to the envelope (image display device) 88 and to display and/or reproduce the information.
The interface unit C30 can be connected to an image recording apparatus or to an image output apparatus (not shown), such as a printer, a digital video camera, a digital camera, a hard disk drive (HDD) or a digital video disk (DVD). With the thus structured information display/reproduction apparatus (or television), an image stored in the image recording apparatus can be displayed on the display panel C11, or an image displayed on the display panel C11 can be processed, as needed, and output to the image output apparatus.
The configuration of the image display device described above is merely an example to which the present invention can be applied, and various modifications are available based on the technical idea of the invention. Further, various information display/reproduction apparatuses can be provided when the image display device of the invention is connected to a system, such as a video conference system or a computer system.
The present invention will now be described in more detail while referring to the embodiments described below.
The basic configuration of an electron-emitting device manufactured in accordance with this embodiment is the same as that in
(Step-a) First, the first auxiliary electrode 2 and the second auxiliary electrode 3 are formed on the silica glass 1 that has been cleaned (
Specifically, a registration pattern is prepared in advance on the substrate 1 in consonance with the space between the first auxiliary electrode 2 and the second auxiliary electrode 3. Then, Ti, 5 nm thick, and Pt, 45 nm thick, are deposited in order, and the registration pattern is melted by using an organic solvent to lift off the Pt/Ti film. As a result, the first auxiliary electrode 2 and the second auxiliary electrode 3 are formed. The distance between the first and the second auxiliary electrodes 2 and 3 is preferably 20 μm, and the widths of the first and the second auxiliary electrodes 2 and 3 are 500 μm.
(Step-b) A Cr film, 100 nm thick, was deposited on the substrate 1 by vacuum evaporation, and an opening is patterned in consonance with a conductive film that will be described later. Then, an organic palladium compound solution is applied to the substrate 1 by a spinner, and the resultant substrate 1 is annealed at 300° C. for twelve minutes. The thus formed conducive film 4, which contains Pd as the main element, preferably is 6 nm thick, and the sheet resistance Rs preferably is 3×104 Ω/□.
(Step-c) The Cr film and the conductive film 4 obtained after being annealed are etched using an acid etchant, and the conductive film 4, having a width of preferably 100 μm, is obtained (
Through (Step-a) to (Step-c), described above, the first auxiliary electrode 2, the second auxiliary electrode 3 and the conductive film 4 are formed on the substrate 1. (Step-d) Then, the substrate 1 wherein the conductive film 4 was deposited is placed in the measurement/evaluation apparatus shown in
A voltage waveform used for this “forming” process is shown in
(Step-e) Sequentially, methanol is introduced to the vacuum apparatus through a slow leak valve, and the pressure level of 1.3 ×10−4 Pa is maintained. In this state, the pulse voltage having a waveform shown in
During the “activation” process, the first auxiliary electrode 2 is constantly secured to the ground potential, and the pulse voltage having the waveform shown in
When sixty minutes have elapsed, it is confirmed that the “activation” process has already entered the area to the right of the broken line in
At this step, three electron-emitting devices are manufactured: an electron-emitting device obtained through the “activation” process under a condition wherein the maximum voltage value in the waveform in
The electron-emitting devices manufactured using the same method used for (Step-a) to (Step-e), described above, were prepared, and the plane SEM images and cross-section SEM images of these devices are observed. As is shown in
(Step-f) The electron-emitting devices manufactured at (Step-a) to (Step-e) in this embodiment are extracted to the air from the measurement/evaluation apparatus in
During the “activation” process, for the individual electron-emitting devices obtained by changing the maximum value of the voltage to be applied, the thickness of the first portion B is adjusted to 20 nm using the AFM. It should be noted that a difference h (the height h of the “projected portion” between the first portion B and the second and the third portions 35 and 36) is 80 nm. Further, electron-emitting devices are manufactured for which there are nine distances w between the second and the third portions 35 and 36 (the “projected portions”), 5 nm, 9 nm, 13 nm, 30 nm, 50 nm, 100 nm, 200 nm, 300 nm and 500 nm (see
Electron-emitting devices for comparison example 1 are manufactured using the same method as in (Step-a) to (Step-e), described above. Furthermore, except for changing a voltage waveform at (step-e), electron-emitting devices for comparison example 2 are manufactured using the same method as in (Step-a) to (Step-e). It should be noted that (Step-f) is not performed for the electron-emitting devices for comparison examples 1 and 2.
During the “activation” process for the electron-emitting devices for comparison example 2, the waveform in
The cross-section SEM images of the thus obtained electron-emitting devices for comparison example 2 are observed. Basically, as is shown in
(Step-g) Next, the electron-emitting devices of the invention after (Step-f) is completed and the electron-emitting devices for comparison examples 1 and 2 obtained through (Step-e) without performing (Step-f) are placed in the measurement/evaluation apparatus in
For the measurement of the electron emission characteristic, the distance H between the anode electrode 44 and the electron-emitting device is defined as 2 mm, and a potential of 1 kV is applied to the anode electrode 44 by the high voltage power source 43. In this state, the power source 41 applies a voltage to the auxiliary electrodes 2 and 3, so that the potential of the first auxiliary electrode 2 is higher than the potential of the second auxiliary electrode 3. At this time, a rectangular pulse voltage having a pulse height of 10 V is applied to the electron-emitting device to which the voltage of ±12 V had been applied during the “activation” process, a rectangular pulse voltage having a pulse height of 20 V is applied for the electron-emitting device to which the voltage of ±22 V had been applied during the “activation” process, and a rectangular pulse voltage having a pulse height of 28 V is applied to the electron-emitting device to which the voltage of ±30 V had been applied during the “activation” process.
In the measurement of the electron emission characteristic, the ammeters 40 and 42 are employed to measure the device currents If and the emission currents Ie of the electron-emitting devices of the invention and comparison examples 1 and 2, and the electron emission efficiencies for these devices are calculated.
The obtained electron emission efficiencies are shown in Table 1 below, and the obtained emission currents Ie are shown in Table 2. The device currents If were from 0.8 mA to 1.4 mA for all the applied voltages of 12 V, 22 V and 30 V during the “activation” process.
[Table 1]
[Table 2]
As is apparent from these results, when the distance between the second portion 35 and the third portion 36 is equal to or longer than 2 d and equal to or shorter than 50 d, the emission current Ie of the electron-emitting devices of the invention is larger than that for the electron-emitting devices for comparison example 1, and the electron emission efficiency η is superior.
In addition, after the characteristics are evaluated, the electron-emitting devices of the embodiment are driven for an extended period of time by applying the same pulse voltage as were applied for the characteristic evaluation. As a result, the characteristics shown in Tables 1 and 2 could be maintained for a long time.
After the characteristics are evaluated, the cross-section SEM images of the individual electron-emitting devices of this embodiment are observed. The thickness D (“depth” D) of the second carbon film 21b in the direction in which the portion A of the first carbon film 21a is opposite the portion B of the second carbon 21b (the direction in which the electrons are emitted) is 20 nm (see
Moreover, it was also confirmed that the substrate-deformed portion (recessed portion) 22 was also formed in the surface of the substrate 11 between the carbon films 21a and 21b.
In a second embodiment of the present invention, a difference h of the thickness between the first portion B and the second and the third portions 35 and 36 is changed.
In this embodiment, electron-emitting devices are manufactured in the same manner as in the first embodiment, except that in (Step-f) in the first embodiment is changed to the following method. Thus, only (Step-f) will now be explained. Comparison examples 1 and 2 are also the same as those used in the first embodiment.
(Step-f) The electron-emitting devices of this embodiment manufactured at (Step-a) to (Step-e) are extracted to the air from the measurement/evaluation apparatus in
During the “activation” process, for the individual electron-emitting devices manufactured by changing the maximum value of the applied voltage, the thickness of the first portion B is adjusted to 20 nm by using the AFM, and the distance w between the second portion 35 and the third portion 36 is adjusted to 30 nm. Then, nine types of electron-emitting devices are provided wherein the differences h of the thickness between the first portion B and the second and the third portions 35 and 36 are 3 nm, 5 nm, 7 nm, 9 nm, 11 nm, 13 nm, 30 nm, 50 nm and 80 nm. Since the end A of the carbon film 21a is not scraped and remained unprocessed, the thickness of the end A is 20 nm. This process is performed at multiple places along the gap 8, specifically, at the portions where the gap 8 is narrower than at the other areas, i.e., where the distance between the first and the second carbon films is shorter.
The electron emission characteristics of the electron-emitting devices manufactured in the second embodiment is measured in the same manner as in the first embodiment. The electron emission efficiencies obtained by calculation are shown in Table 3, and the emission currents Ie obtained by measurement are shown in Table 4.
[Table 3]
[Table 4]
From these results, compared with the electron-emitting devices for comparison examples 1 and 2, it is apparent that the emission current Ie is large and the electron emission efficiency η is superior for the electron-emitting devices of the invention when the difference h of the thickness between the first portion B and the second and the third portions 35 and 36 is equal to or greater than 2 d.
Furthermore, it is also known through calculations performed by the present inventors that, when the difference h of the thickness between the first portion B and each of the second and the third portions 35 and 36 is equal to or greater than 80 nm, the emission current Ie and the electron emission efficiency η are greater than those obtained for the electron-emitting devices manufactured for comparison examples 1 and 2. Therefore, there is no upper limit to the difference h of the thickness between the first portion B and the second and the third portions 35 and 36. However, for the image display device employing the electron-emitting device of the invention, it is preferable that the thickness difference h be equal to or smaller than 200 d because of manufacturing costs and quality control (e.g., prevention of discharge).
After the characteristics are evaluated, the electron-emitting devices of this embodiment were driven for an extended period of time by applying the same pulse voltage as was applied for the characteristic evaluation. As a result, the characteristics shown in Tables 3 and 4 could be maintained for a long time.
After the characteristics are evaluated, the cross-section SEM images of the electron-emitting devices of this embodiment are observed. The thickness of the first portion B of the second carbon film 21b is 20 nm, and the distance w of the second and the third portions 35 and 36 of the second carbon film 21b is 30 nm. The thickness D (“depth” D) of the second carbon film 21b in the direction in which the portion A of the first carbon film 21a is opposite the portion B of the second carbon film 21b (the direction in which the electrons are emitted) is 20 nm (see
Moreover, the substrate-deformed portion (recessed portion) 22 is formed in the surface of the substrate 1 between the first and the second carbon films 21a and 21b.
In a third embodiment, there is a change in the thickness D (“depth” D) of the second carbon film 21b that is present in the direction in which the portion A of the first carbon film 21a is opposite to the portion B of the second carbon film 21b (the direction in which electrons are emitted).
In this embodiment, electron-emitting devices are manufactured in the same manner as in the first embodiment, except that (Step-f) in the first embodiment is changed, and that only (Step-f) will now be described. Comparison Examples 1 and 2 are also the same as those used for the first embodiment.
(Step-f)
The electron-emitting devices manufactured in this embodiment at (Step-a) to (Step-e) are extracted to the air from the measurement/evaluation apparatus in
During the “activation” process, for the individual electron-emitting devices manufactured by changing the maximum value of the voltage to be applied, the thickness of the first portion B is adjusted to 20 nm by using the AFM. Furthermore, the distance w between the second and the third portions 35 and 36 is defined as 30 nm, and the thickness difference h between the first portion B and the second and the third portions 35 and 36 is defined as 80 nm. As a result, seven types of electron-emitting devices are provided wherein the thicknesses D (the “depths” D) for the second carbon film 21b, in the direction in which the portion A of the first carbon film 21a is opposite the portion B of the second carbon film 21b, are 3 nm, 5 nm, 7 nm, 10 nm, 30 nm, 50 nm and 100 nm. Since the end A of the carbon film 21a is not scraped and remained unprocessed, the thickness of the end A was 20 nm. This process is performed at multiple places along the gap 8, specifically, at the portions where the gap 8 is narrower than at the other areas, i.e., where the distance between the first and the second carbon films is shorter.
The electron emission characteristics of the electron-emitting devices of the third embodiment are measured in the same manner as in the first embodiment. The electron emission efficiencies obtained through calculation are shown in Table 5, and the emission currents Ie obtained through measurement are shown in Table 6.
[Table 5]
[Table 6]
According to these results, compared with the electron-emitting devices for comparison examples 1 and 2, the emission current Ie is large and the electron emission efficiency η is superior for the electron-emitting devices of the invention, regardless of the thickness D of the second carbon film 21b (the “depth” D) present in the direction in which the portion A of the first carbon film 21a is opposite the portion B of the second carbon film 21b (the direction in which electrons are emitted).
It is also known through calculation performed by the present inventors that, when the thickness D of the second carbon film 21b, present in the direction in which the portion A of the first carbon film 21a is opposite the portion B of the second carbon film 21b, is equal to or greater than 10 nm, the emission current Ie and the electron emission efficiency η are greater than those for the electron-emitting devices for comparison examples 1 and 2. Therefore, so long as the second carbon film 21b is thick enough to appropriately provide a potential, there is no specific limit on the thickness D of the second carbon film 21b in the direction in which the portion A of the first carbon film 21a is opposite the portion B of the second carbon film 21b (the direction in which electrons are emitted).
However, for an image forming apparatus or an image display device employing the electron-emitting device of this invention, it is preferable that the thickness D of the second carbon film 21b be equal to or smaller than 200 d because of manufacturing costs and quality control (e.g., prevention of discharge).
After the characteristics are evaluated, the electron-emitting devices of this embodiment are driven for an extended period of time by applying the same pulse voltage as was applied for the characteristic evaluation. As a result, the characteristics shown in Tables 5 and 6 could be maintained for a long time.
After the characteristics are evaluated, the cross-section SEM images of the individual electron-emitting devices of the embodiment are observed. The thickness of the first portion B of the second carbon film 21b is 20 nm, the thickness difference h between the first portion of the second carbon film 21b and the second and third portions 35 and 36 of the second carbon film 21b is 80 nm, and the distance w between the second and the third portions 35 and 36 is 30 nm. Further, it could be confirmed that the thicknesses D for the second carbon film 21b, in the direction in which the portion A of the first carbon film 21a is opposite the portion B of the second carbon film 21b (direction in which electrons are emitted), are 3 nm, 5 nm, 7 nm, 10 nm, 30 nm, 50 nm and 100 nm.
Furthermore, it could be confirmed that the substrate-deformed portion (recessed portion) 22 is formed in the surface of the substrate 1 between the first and the second carbon films 21a and 21b.
In a fourth embodiment of this invention, an electron source is constituted by arranging the electron-emitting devices of the invention in a matrix shape, and an image display device is provided by using this electron source. The processing according to this embodiment for manufacturing the image display device will now be described.
(Auxiliary Electrode Generation Step)
A PD-200, 2.8 mm thick glass plate (by Asahi Glass Co., Ltd.) that contains a small amount of alkaline elements is employed as the substrate 71. Then, an SiO2 film of 100 nm is deposited on this substrate 71.
Then, the process for forming multiple first and second auxiliary electrodes 2 and 3 on the substrate 71 is performed (
(Y-Directional Wiring Formation Step)
As is Shown in
(Insulating Layer Formation Step)
As is shown in
Specifically, a photosensitive glass paste containing PbO as a main element is screen-printed, the exposure process and the developing process are repeated four times, and finally, the resultant structure is annealed at a temperature of around 480° C. The thickness of the insulating layer 75 is 30 μm and the width thereof is 150 μm.
(X-directional Wiring Formation Step)
As is Shown in
The substrate 71 having matrix wiring is thus obtained.
(First Electrode and Second Electrode Formation Step)
The substrate 71 having the matrix wiring is appropriately cleaned, and the surface is processed by using a solution containing a water repellent to obtain a hydrophobic surface. Through this process, a solution that is applied later for forming a conducive film could appropriately be spread over the auxiliary electrodes 2 and 3. Thereafter, using the ink jet coating method, the conductive film 4 is deposited between the auxiliary electrodes 2 and 3 (
In this embodiment, ink used for the ink jet coating method is an organic palladium containing a solution wherein a palladium-proline complex of 0.15 weight % is dissolved in an aqueous solution (water: 85%, isopropyl alcohol (IPA): 15%). An ink jet ejection apparatus employing piezoelectric devices is employed to spray the organic palladium containing solution onto the auxiliary electrodes 2 and 3, while the dot diameter is adjusted to 60 μm. Thereafter, the substrate 71 is heated in the air at 350° C. for ten minutes, and the conductive film 4 made of palladium(II) oxide (PdO) is obtained. The diameter of the dot is about 60 μm, and the maximum thickness of the film is 10 nm.
Then, the substrate 71 wherein multiple units, including the auxiliary electrodes 2 and 3 and the conductive film 4 connecting these electrodes, are formed through the above described steps is placed in the vacuum container 23. Thereafter, the pressure in the vacuum container 23 is reduced to be equal to or lower than 1.3×10−3 Pa, and the introduction of a reduction gas (a gas mixture of N2=98% and H2=2%) into the vacuum container 23 is started. Then, the “forming” process is initiated.
The “forming” process is performed by applying one pulse selectively to each of the X-directional wirings 72. That is, the process for applying one pulse to one selected X-directional wiring 72, and applying one pulse to another selected X-directional wiring 72 is repeated. The waveform of the pulse voltage to be applied is a triangular pulse, as is shown in
After the air is removed from inside the vacuum container 23, the “activation” process is performed. In this embodiment, methanol is employed as a carbon containing gas, and the activation process is performed when the pressure in the vacuum container 23 is 1.3×10−4 Pa. The pressure of methanol to be introduced is a little affected by the shape of the vacuum apparatus and the member used for the vacuum apparatus, and 1×10−5 Pa to 1×10−2 Pa is appropriate. Further, during the “activation” process, the bipolar pulse waveform in
After sixty minutes has elapsed since the start of the “activation” process, it is confirmed that the “activation” process has entered the area to the right of the broken line shown in
Through the above-described steps, the substrate 71, wherein multiple electron-emitting devices are arranged, could be obtained.
By performing the above-described steps, substrates are prepared on which multiple electron-emitting devices are provided for measurement, and the cross-section TEM images of the individual electron-emitting devices are observed. As schematically shown in
The substrate 71 on which provided were multiple electron-emitting devices are provided, for which the “activation” process has been completed, is extracted to the air from the vacuum container, and as described above, the end of the second carbon film 21b is changed by using the AFM (see
By scraping the end of the second carbon film 21b using the AFM, the first portion B, the second portion 35 and the third portion 36 are formed (
Through the above-described steps, the substrate 71, on which the electron source of the invention (a plurality of the electron-emitting devices) is mounted, is obtained.
Sequentially, as is shown in
In this embodiment, in order to provide a color display, the fluorescent film 84, which is an image forming member, is a stripe phosphor (see
The metal back 85 could be obtained by depositing aluminum, by vacuum evaporation, on the inner wall of the fluorescent film 84 (near the electron-emitting device).
For the thus completed image display device, a desired electron-emitting device is selected via the X-directional wiring and the Y-directional wiring, and a pulse voltage of +20 V is applied to the selected electron-emitting device, so that the potential of the second auxiliary electrode of this electron-emitting device is higher than the potential of the first auxiliary electrode. At the same time, a voltage of 8 kV is applied to the metal back 85 via the high voltage terminal Hv. As a result, a bright, satisfactory image could be displayed for an extended period of time.
The mode and embodiments described above are merely examples, and various modifications for the members and the sizes of the members are also included within the steps of the present invention.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited only to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims priority from Japanese Patent Application No. 2004-147836 filed May 18, 2004 and Patent Application No. 2005-110981 filed Apr. 7, 2005, which are hereby incorporated by reference herein, its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-147836 | May 2004 | JP | national |
| 2005-110981 | Apr 2005 | JP | national |
This application is a division of U.S. application Ser. No. 11/131,195, filed May 18, 2005.
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| Number | Date | Country | |
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| Parent | 11131195 | May 2005 | US |
| Child | 12481851 | US |
