JP2004095544A - Field emission type electron source device and image display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable field emission type electron source device without lowering current even if a long time operation under a high current density is carried out, and to provide a high performance image display that maintains a stable display performance in a long term. <P>SOLUTION: The field emission type electron source device comprises: a cathode plate 11; an insulating layer 13 formed on the cathode plate 11, and having an opening 12; a lead out electrode 14 formed on the insulating layer 13; and an emitter 15 formed in the opening 12. At least one reducing component selected from hydrogen or carbon mono oxide is doped in the surface layer 16 of the electron emitting area of the emitter 15. The image display includes the field emitter. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a cathode ray tube (CRT) used for a color television or a high-definition monitor television, and further relates to an electron gun used for an electron beam exposure apparatus utilizing a converged electron beam, and particularly requires a high current density operation. Field of the Invention The present invention relates to a field emission type electron source element used for a high-brightness CRT electron gun and an image display device using the same.

In recent years, thin displays such as liquid crystal displays and plasma displays have appeared, and the flat display market has been rapidly expanding. However, CRT displays are still used for home TVs of about 32 inches in terms of price and performance in terms of price and performance. You have an advantage. Also, when terrestrial digital broadcasting is newly introduced, it is expected that the display technology for television will change significantly. As the environment surrounding televisions shifts to digital systems, high resolution performance is particularly required for displays.

However, there is a possibility that television technology that has been widely used until now cannot sufficiently meet these demands. That is, an electron gun is used as the heart of a television to display an image, and the performance of the electron gun is strongly related to the resolution performance. If the current density of the cathode used in the electron gun is increased, the effective cathode area can be reduced, and as a result, the resolution performance can be improved. At present, the hot cathode materials used as cathodes for electron guns have been improved in current density by various technical improvements, but are now approaching the physical limit, It is difficult to dramatically improve the current density. In recent years, cathodes for electron guns for digital broadcasting, which are being put to practical use, are required to have a current density improvement of about 6 to 10 times that of conventional hot cathodes. For these reasons, cold cathodes are expected as a technology that responds to a significant improvement in current density.

On the other hand, the idea of using a cold cathode for an electron gun has been proposed. Cold cathodes have the feature that the current density can be increased because a microstructured cathode can be integrated at a high density, and they have been commercialized in some products such as electron beam microscopes. Was.

Patent Document 1 discloses a color picture tube using a field emission cathode as the first proposal using a cold cathode for a CRT. The merit of using a field emission cathode for a color picture tube is that it is advantageous in reducing power consumption in addition to the above-described high current density. In the conventional hot cathode method, a heater for heating is required to emit electrons, and a standby power of about several watts is always required even when the electron gun is not used. However, in the case of the field emission type cathode, since no heater for heating is required, there is an advantage that not only waste of standby power can be saved but also the electron gun can be instantaneously started.

Generally, a high melting point metal such as molybdenum is often used as a material for the cold cathode. The degree of vacuum in the tube of the CRT completed through the CRT manufacturing process is usually about 10 ^-4 Pa due to restrictions in the manufacturing process and problems due to the structure of the CRT. When the cold cathode is operated at a current density of about 10 A / cm ² under this level of vacuum environment, the following problem occurs. That is, various types of residual gas generated in the manufacturing process exist in the CRT. Of these constituent elements of the residual gas, the oxygen element (O) and the carbon element (C) temporarily adhere to the surface of the emitter or change the surface composition of the emitter, thereby lowering the emission performance of the cold cathode. It is known.

To solve these problems, Patent Literature 2 discloses stabilizing emission current using hydrogen gas (H ₂ ). Hereinafter, this will be described with reference to FIG. 8 which shows a cross-sectional view of a field emission type light emitting device using a conventional field emission type electron source device.

陰極 The cathode conductor 3 is formed on the upper surface of the cathode substrate 2 of the field emission light emitting device 1, and the insulating layer 4 is formed on the cathode conductor 3. A gate 5 is formed on the insulating layer 4, and the gate 5 contains a hydrogen storage metal such as Nb, Zr, V, Fe, Ta, Ni, Ti, or the like. A plurality of openings 6 continuous in the thickness direction are formed in the gate 5 and the insulating layer 4. An emitter 7 is formed on the cathode conductor 3 exposed at the bottom of the opening 6 of the insulating layer 4. An anode conductor 9 is formed on the inner surface of the anode substrate 8, and a phosphor layer 10 is formed on the anode conductor 9.

When the field emission light emitting device 1 is turned on, a drive signal is applied to the anode conductor 9, an intersection of the matrix is selected by the cathode conductor 3 and the gate 5, and the phosphor layer 10 corresponding to a desired position of the anode conductor 9 emits light. The anode conductor current is constantly monitored, and when the anode conductor current falls below a certain level, a signal is given to the gate 5 when the lamp is not lit. As a result, when electrons strike the gate 5, hydrogen and methane (CH ₄ ) are emitted near the emitter 7 to remove oxygen and carbon elements attached to the emitter 7, thereby increasing the work function of the emitter 7. Prevent and restore emission performance. As a result, long life and high reliability of the emitter 7 are ensured.

In this conventional example, a method is employed in which electrons are made to collide with a gate 5 made of a hydrogen storage metal, thereby temporarily removing an oxygen element or a carbon element attached to the emitter 7 to recover emission performance. When a high melting point metal such as molybdenum is used as the material of the emitter, the chemical bonding force between the high melting point metal on the surface of the emitter 7 and the oxygen element or carbon element attached thereto is weak. According to the method, the oxygen element and the carbon element can be relatively easily removed.
JP-A-48-90467 JP 2000-36242 A

However, when another material such as silicon is used as the material of the emitter, there is a problem that the emission performance cannot be recovered even by using the above-described conventional method. In other words, the outermost surface of the cleaned silicon that acts as an emitter is present in a state of being chemically unstable, in which bonds of silicon (bonding bonds) exist without being terminated. Here, if an oxidizing gas such as H ₂ O or CO ₂ exists even in a small amount in the vicinity of the emitter, the oxygen element of the oxidizing gas easily bonds to silicon dangling bonds on the silicon surface, and A SiO ₂ film is formed. The SiO ₂ film formed on the surface of the emitter deteriorates the electron emission performance of the emitter, and as a result, the emission current is significantly reduced. In addition, since the SiO ₂ film is extremely chemically stable, once a bond between Si and O has been formed on the emitter surface, it must be removed later using a conventional gas such as hydrogen or methane. Is extremely difficult, and there is a big problem that the emission performance cannot be recovered. Therefore, when a material that easily forms a stable oxide film, such as a silicon material, is used as the emitter, it is an essential element not to form an oxide film that deteriorates emission performance on the surface of the emitter.

The present invention provides a stable field-emission electron source element that does not cause a current drop even when operated at a high current density for a long time, and a high-performance image display device that can maintain stable display performance for a long time. To provide.

The present invention provides a field emission type including a cathode substrate, an insulating layer formed on the cathode substrate and having an opening, a lead electrode formed on the insulating layer, and an emitter formed in the opening. An electron source element,
A field emission type electron source device characterized in that a surface layer of an electron emission region of the emitter is doped with at least one reducing element selected from hydrogen and carbon monoxide.

The present invention also provides an image display device including the above field emission type electron source element.

Further, the present invention provides a vacuum vessel, an electron gun disposed in the vacuum vessel, means for deflecting an electron beam emitted from the electron gun, and a phosphor layer provided at a position facing the electron gun. An image display device comprising:
The electron gun includes the field emission type electron source element,
An image display device comprising means for controlling an atmosphere in the vacuum vessel to an atmosphere having a reducing effect on a material of an emitter of the field emission electron source element.

Further, the present invention provides a vacuum vessel, an electron gun disposed in the vacuum vessel, means for deflecting an electron beam emitted from the electron gun, and a phosphor layer provided at a position facing the electron gun. An image display device comprising:
The electron gun includes a field emission type electron source element having an emitter,
An image display device comprising means for controlling an atmosphere in the vacuum vessel to an atmosphere having a reducing action on a material of the emitter.

In the field emission type electron source device of the present invention, the surface of the emitter (cathode) is oxidized by doping the surface layer of the electron emission region of the emitter with at least one reducing element selected from hydrogen and carbon monoxide. Since it can be effectively prevented, stable electron emission performance can be maintained.

Further, since the image display device of the present invention includes means for controlling the atmosphere in the vacuum vessel to an atmosphere having a reducing action on the material of the emitter of the electron gun, a field emission type used as a cathode of the electron gun is provided. Performance degradation due to oxidation of the electron source element can be effectively prevented, and a great effect can be exerted on long life operation and stable operation.

Hereinafter, embodiments of the present invention will be described.

One example of the field emission type electron source element of the present invention is a cathode substrate, an insulating layer formed on the cathode substrate and having a plurality of openings, an extraction electrode formed on the insulating layer, and the cathode substrate. A plurality of emitters (cathodes) formed in the plurality of openings above, and a surface layer of an electron emission region of the emitter has at least one reducing element selected from hydrogen and carbon monoxide. Is doped.

Hydrogen and carbon monoxide have a reducing action, and by doping the above-mentioned reducing element into the surface layer of the electron emission region of the emitter, oxidation of the emitter surface can be effectively prevented, and a long current at a high current density can be obtained. It is possible to obtain a stable field emission type electron source element that does not cause a decrease in current even after performing the time operation.

エ ミ ッ タ Here, the emitter is a portion that emits electrons in a field, and is usually formed in a cone shape. The tip of the cone-shaped emitter becomes a substantial electron emission region. Therefore, in the field emission type electron source element of the present embodiment, it is necessary to dope the reducing element at least to the surface layer of the electron emission region, but the entire surface of the emitter may be doped with the reducing element. Further, a part of the surface of the emitter including the electron emission region may be doped with the reducing element.

The emitter is preferably formed from a material containing silicon. This is because silicon can be stably doped with the reducing element. As silicon, crystalline silicon, amorphous silicon, polysilicon or the like can be used.

The emitter may be formed of a metal, and a thin film containing silicon may be formed on a surface of the metal. This is because the above-mentioned reducing element can be stably doped into a thin film containing silicon. As the metal, a high melting point metal such as molybdenum and tungsten can be used.

{Circle around (5)} The thickness of the surface layer of the emitter doped with the reducing element is preferably 5 nm or more and 30 nm or less, more preferably 10 nm or more and 20 nm or less. This is because if the content is within this range, the reducing element can be doped without excess or shortage.

It is preferable that the reducing element is doped by an ion doping method. The ion doping method is a method conventionally used in a semiconductor manufacturing process, and has high reliability of ion doping.

Further, it is more preferable that the reducing element is doped by a plasma doping method. This is because the plasma doping method can dope the reducing element at a higher concentration than the ion doping method, and can further prevent the oxidation of the emitter surface.

One example of the image display device of the present invention is a vacuum container, an electron gun disposed in the vacuum container, means for deflecting an electron beam emitted from the electron gun, and a device provided at a position facing the electron gun. And the electron gun includes the field emission type electron source element.

Further, another example of the image display device of the present invention includes a vacuum container, an electron gun arranged in the vacuum container, a unit for deflecting an electron beam emitted from the electron gun, and a device facing the electron gun. The electron gun includes a field emission type electron source element having an emitter, and reduces an atmosphere in the vacuum vessel with respect to a material of the emitter (cathode). Means for controlling the atmosphere to have the following.

As a result, the inside of the vacuum vessel can always be kept in a reducing atmosphere, so that oxidation of the emitter surface can be effectively prevented, stable electron emission can be maintained, and stable display performance can be maintained for a long period of time. A high-performance image display device can be obtained.

Further, in order to control the atmosphere to have the above-mentioned reducing action, it is preferable to arrange a hydrogen storage material in the above-mentioned vacuum vessel. Thereby, the inside of the vacuum vessel can be maintained in a reducing atmosphere using a simple and minimal space.

As the hydrogen storage material, it is preferable to use a material containing at least one kind of carbon nanotube, graphite nanofiber, another carbon material, or the like. These materials have an excellent hydrogen storage capacity, which allows the inside of the vacuum vessel to be kept in a reducing atmosphere, so that oxidation of the emitter surface can be effectively prevented, and more stable electron emission can be maintained. Because.

Also, it is preferable to use a material containing a hydrogen storage metal as the hydrogen storage material. This material has an excellent hydrogen storage capacity, which can further keep the inside of the vacuum vessel in a reducing atmosphere, effectively prevent oxidation of the emitter surface, and maintain more stable electron emission. It is.

Further, in the image display device of the present embodiment, it is preferable that a heating unit is further disposed near the material containing the hydrogen storage material. As a result, the release of hydrogen (H ₂ ) from the hydrogen storage material can be promoted, and the inside of the vacuum vessel can be further kept in a reducing atmosphere, so that oxidation of the emitter surface can be effectively prevented and more stable This is because electron emission can be maintained.

Further, it is preferable that the above-mentioned electron gun is provided with the above-mentioned field emission type electron source element of the present embodiment. By doping the surface layer of the electron emission region of the emitter with at least one reducing element selected from hydrogen and carbon monoxide, and maintaining the inside of the vacuum vessel in a reducing atmosphere, the oxidation of the emitter surface is ensured. This is because it is possible to obtain a high-performance image display device that can prevent the electron emission, maintain more stable electron emission, and maintain stable display performance for a longer period of time.

Next, embodiments of the present invention will be described more specifically with reference to the drawings.

(Embodiment 1)
FIG. 1 is a sectional view showing an example of the field emission type electron source device of the present invention. As shown in FIG. 1, on a cathode substrate 11, an insulating layer 13 having a circular opening 12 in a cathode forming region in an array is formed. On the insulating layer 13, an extraction electrode 14 for controlling emission of electrons is formed.

As the material of the cathode substrate 11, an optimal material such as a normal glass substrate or a silicon substrate can be used in consideration of the characteristics of the electron source element and the process conditions. As a material of the insulating layer 13, a silicon oxide film (SiO ₂ ) or a silicon nitride film used in a semiconductor manufacturing process, a film combining these films, or the like can be used. As a material of the extraction electrode 14, a wiring material using a high melting point metal such as a low resistance polysilicon film or a tungsten film can be used.

An emitter (cathode) 15 serving as an electron emission portion is formed inside the opening 12 of the insulating layer 13 and the extraction electrode 14, and a field emission type electron source array portion including a plurality of emitters 15 is provided on a cathode substrate. 11 is formed on the entire surface of the surface or a desired part of the surface. Although the shape of the emitter 15 is not particularly limited, a cone shape having a sharp acute end portion is usually adopted.

(4) As a material of the emitter 15, a semiconductor such as crystalline silicon, amorphous silicon, or polysilicon can be used. In this case, as a method for manufacturing the emitter 15, a semiconductor manufacturing process such as a vapor deposition method, a sputtering method, or a CVD method can be used. When a high melting point metal such as molybdenum or tungsten is used as the material of the emitter 15, a thin film made of silicon is formed on the surface of the high melting point metal to facilitate doping of the reducing element. In this case, as a method of manufacturing the emitter 15, a method of forming an emitter main body made of a high melting point metal by a vapor deposition method or the like, and then forming a silicon thin film on the surface of the high melting point metal by the above semiconductor manufacturing process can be used.

(4) The surface layer 16 of the emitter 15 is doped with at least one reducing element selected from hydrogen and carbon monoxide. Here, since the tip of the cone-shaped emitter 15 becomes a substantial electron emission region, it is necessary to dope the reducing element to at least the surface layer of the electron emission region. The reducing element may be doped, or a part of the surface layer of the emitter including the electron emission region may be doped with the reducing element.

Next, the field emission type electron source device according to the present embodiment will be described by taking silicon as an example of the material of the emitter 15 as an example.

As described above, a silicon material easily reacts with an oxidizing gas in an oxidizing gas atmosphere, and has a property of easily forming an SiO ₂ film as an oxide film. Simply exposing the cleaned silicon surface to the air at room temperature forms a few atomic layer SiO ₂ film on the surface within a few minutes. The degree of vacuum in a tube of a CRT is usually about 10 ⁻⁴ Pa due to a problem due to a limitation of a manufacturing process and a structure of the CRT. As the residual gas in the CRT, an oxidizing gas such as H ₂ O or CO ₂ is also contained in a large amount. When the cold cathode is operated at a current density of about 10 A / cm ² even in a vacuum environment of this level, the silicon surface (emitter surface) of the field emission type electron source element, which is the operating region of the cold cathode, is emitted. It is activated by ions generated by collision with electrons and residual gas. Even in a vacuum environment, the activated silicon surface and the ionized oxidizing gas are easily chemically bonded to each other, and the outermost surface of the silicon is covered with an oxide SiO ₂ film. Has been revealed by our recent research. This is the biggest technical problem when using a silicon material as a cathode for CRT.

On the other hand, it is known that, for example, hydrogen and carbon monoxide have a reducing action on silicon materials. Therefore, by doping the surface layer of silicon with a reducing element such as hydrogen or carbon monoxide, an effect of suppressing the oxidation of the silicon surface by the oxidizing gas can be expected. As a method for forming a doped layer having an oxidation preventing function on a silicon surface, there are a plurality of methods such as an ion doping method and a plasma doping method.

In the present embodiment, the size of each part of the field emission type electron source element and the method of manufacturing each part are not particularly limited, and can be appropriately selected.

In this embodiment, the field emission type electron source device has been described by taking a typical cathode ray tube (CRT) as an example. However, the application is not limited to the cathode ray tube. It can be applied to a high-luminance light-emitting display tube, a light-emitting display tube for illumination, and the like.

Next, an example of manufacturing a field emission type electron source element by using an ion doping method for manufacturing a thin film transistor (TFT) device used for a liquid crystal display will be described with reference to the drawings.

FIG. 2 is a cross-sectional view showing an example of a process for manufacturing the field emission electron source device of the present embodiment. As shown in FIG. 2, after completing the field emission type electron source device, an ion doping process using hydrogen ions as an ion source is performed over the entire surface of the field emission type electron source device. As the process conditions, the acceleration energy may be set to about ²⁰ to 30 keV, and the doping amount may be set to about 5 × 10 ¹⁵ atom / cm ² .

By the ion doping process, a surface layer 16 doped with hydrogen ions at a high concentration is formed on the entire surface of the emitter 15 made of silicon or at least a part of the surface including the electron emission region. Further, in order to activate the doped hydrogen ions, annealing is performed at a temperature of 800 ° C. for about 30 minutes in nitrogen or a vacuum atmosphere. By this annealing treatment, hydrogen ions doped on the silicon surface are taken into the silicon crystal, and the antioxidant function is effectively exhibited.

In order to verify the effect of the doped hydrogen ions, the field emission electron source device was continuously operated in a vacuum chamber containing a small amount of oxidizing gas such as H ₂ O, and the current stability was compared. investigated.

When the composition and the partial pressure of the residual gas in the evaluated vacuum chamber were examined using a quadrupole mass spectrometer (Q-Mass), the most dominant residual gas at a total vacuum of 1 × 10 ⁻⁶ Pa was obtained. The main gas was H ₂ O, which accounted for about 70% by volume of the residual gas. In addition, residual gases such as N ₂ (15% by volume), H ₂ (9% by volume), and CO ₂ (6% by volume) were confirmed. Into this vacuum chamber, a field emission type electron source element whose emitter was formed by sputtering using silicon was introduced, and a change in field emission current was measured.

主 The main configuration of the field emission type electron source device is as follows. As the extraction electrode, polysilicon subjected to a conductive treatment generally used in a semiconductor manufacturing process was used, and the opening diameter was about 0.6 μm. The radius of curvature of the tip of the emitter, which affects the field emission characteristics, was set to about several nm using the sharpening effect of thermal oxidation of silicon. The number of the emitters was 1000, and the distance between the emitters was 1.6 μm. In addition, an emission condition of 100 μA was selected this time as a condition of the emission current that affects current stability as well as the residual gas.

Next, the surface layer of the emitter was doped with hydrogen ions by an ion doping method in the field emission electron source device manufactured under the above configuration and conditions. The doping acceleration voltage was 20 keV, and the doping amount was 5 × 10 ¹⁵ atoms / cm ² . The field emission type electron source device manufactured in this manner was used as the device of the example. A field-emission electron source device manufactured in the same manner as the device of the above example except that hydrogen ions were not doped was used as a device of a comparative example.

FIG. 3 shows the relationship between the elapsed time and the emission current of the field emission electron source devices of the example and the comparative example. In FIG. 3, the emission current value (%) is shown as a relative value when the initial (elapsed time 0) emission current value is 100 (%). As is clear from FIG. 3, the current stability between the field emission type electron source device doped with hydrogen ions (Example) and the field emission type electron source device not doped with hydrogen ions (Comparative Example) was improved. Significant differences occurred. That is, in the device of the comparative example, the emission current value was halved after about 30 hours, whereas in the device of the example, the emission current value of 90% or more was maintained even after the lapse of 30 hours.

Thereafter, the surfaces of both field emission electron source devices were analyzed using Auger electron spectroscopy. As a result, in the device of the comparative example, the surface of the electron emission region was covered with a SiO ₂ film, and this surface oxidation was performed. Was the main factor of the current drop. On the other hand, in the device of Example, the presence of a remarkable SiO ₂ film on the surface of the electron emission region was not confirmed. These analyzes have demonstrated that the surface layer of the emitter doped with hydrogen ions suppresses the oxidizing action of the oxidizing gas and is effective for stable emission operation over a long period of time.

と し て As a method of doping the surface layer of the silicon material with a higher concentration of hydrogen, there is a plasma doping method in addition to the ion doping method. In this method, a plasma of a gas containing a hydrogen element is generated, a silicon material is directly placed in the plasma, and the entire surface of the silicon material is doped with extremely low energy (energy of several keV or less). A high-concentration hydrogen doping layer can be formed in a region having a depth of 10 to 30 nm from the surface of the material. By using this method, it is possible to dope the surface layer of the silicon material with a higher concentration of hydrogen than in the above-described ion doping method, and the effect of preventing oxidation of the emitter can be further enhanced.

As described above, according to the field emission type electron source device according to the present embodiment, the surface of the emitter (cathode) is formed by forming the hydrogen doping layer on the surface layer of the electron emission region of the emitter of the field emission type electron source device. Can be effectively prevented, so that stable electron emission performance can be maintained.

(Embodiment 2)
FIG. 4 is a sectional view showing an example of the image display device of the present invention. As shown in FIG. 4, the image display device of the present embodiment has a deflection yoke in which an electron gun 43 is housed in a neck 42 of a bulb 41 and an electron beam 44 emitted from the electron gun 43 is mounted on the outer periphery of a funnel. The image is formed on the entire surface of the face panel 46 by scanning by 45 and irradiating the fluorescent film 47 on the inner surface of the face panel 46. Further, on the inner surface of the funnel, a conductive material 48 made of a hydrogen storage material and a conductive material such as graphite is disposed. Conventionally, as this conductive material, a conductive paste mainly containing a conductive material such as graphite is usually used in order to maintain a constant potential between the face panel 46 and the neck 42 to which a high voltage of about 30 kV is applied. However, in the present embodiment, the conductive paste is mixed with a hydrogen storage material. This hydrogen storage material may be disposed in a vacuum vessel, and its position is not particularly limited. However, it is easy to include the hydrogen storage material in a conductive material 48 generally used in a CRT in the manufacturing process.

Next, the function of the conductive material 48 containing the hydrogen storage material, which is a feature of the present embodiment, will be specifically described.

Recent research has revealed that the carbon nanotube (CNT) material is a promising material having a hydrogen storage function, and has attracted attention. The mechanism by which CNTs can be treated in a high-pressure hydrogen atmosphere to store hydrogen gas in internal voids such as straws has been elucidated. There are reports that the occlusion amount reaches 10% by weight, depending on the conditions of the hydrogen treatment. By using the CNT material subjected to the hydrogen storage process as a conductive paste material used as a conductive material inside the CRT or as a mixture of the conductive materials, a certain amount of hydrogen is stored in the CRT. It becomes possible. In that case, the amount of CNT and the hydrogen storage condition of CNT can be set so as to always release a fixed amount of hydrogen, assuming a vacuum environment such as a process processing condition for CRT manufacturing and a getter processing condition in a tube. . The partial pressure of hydrogen, which is a reducing gas released from CNT, is always set to be three to ten times higher than the partial pressure of oxidizing gas (H ₂ O, O ₂ , CO _2, etc.) in the CRT. By doing so, it is possible to always keep the inside of the CRT in a reducing gas atmosphere.

In the first embodiment, the structure in which the surface layer of the electron emission region of the emitter of the field emission type electron source element is doped with hydrogen or carbon monoxide to effectively prevent the oxidation of the emitter surface is described. It was confirmed that even in the image display device of the embodiment, an oxidation prevention effect almost equivalent to that of the first embodiment can be obtained. Also in the current stability evaluation experiment by continuous operation as performed in the first embodiment, the emitter of the field emission type electron source element is formed by setting the inside of the CRT to a reducing gas atmosphere using the CNT of the present embodiment. It was confirmed that stable electron emission was obtained over a long period of time.

Further, in the present embodiment, an example is shown in which CNTs having excellent hydrogen storage effect are used. However, other carbon materials such as graphite nanofiber, activated carbon, and fullerene other than CNTs have confirmed the same hydrogen storage effect. It is also possible to use these materials.

In the present embodiment, the size of each part of the image display device and the method of manufacturing each part are not particularly limited, and can be appropriately selected.

In the present embodiment, a typical cathode ray tube (CRT) has been described as an example of the application of the image display device. However, the application is not limited to the cathode ray tube. It can also be applied to a light-emitting display tube for lighting.

As described above, according to the image display device of the present embodiment, by controlling the atmosphere in the vacuum vessel of the CRT to an atmosphere having a reducing effect on the material of the emitter of the electron gun, the surface of the emitter (cathode) is controlled. Oxidation can be effectively prevented, so that stable electron emission performance can be maintained and a great effect can be exerted on long life operation and stable operation.

Further, when the field emission type electron source element used in the first embodiment is used as the field emission type electron source element of the electron gun used in this embodiment, the effect described in the present embodiment is further enhanced, and a more desirable effect is obtained. You can expect it.

(Embodiment 3)
FIG. 5 is a schematic sectional view showing an example of an electron gun used for the image display device of the present invention. In FIG. 5, a field emission type electron source element 51 is fixed on a cathode structure 52. At a position facing the field emission type electron source element 51, an electron lens portion 53 composed of an aggregate of grid electrodes G1 to G5 is arranged. An optimal voltage is applied to each of the grid electrodes G1 to G5 constituting the electron lens portion 53, and has an action of accelerating and converging the electron beam emitted from the field emission type electron source element 51. I have.

In this embodiment, means for controlling the atmosphere in the vacuum vessel of the CRT to an atmosphere having a reducing effect on the material of the emitter of the electron gun is performed by adding the following configuration to the electron gun. That is, among the components of the electron gun, at least any one of the grid electrodes G1 to G5 constituting the cathode structure 52 or the electron lens portion 53 is manufactured using a hydrogen storage metal having a hydrogen storage function. . As the hydrogen storage metal, for example, an alloy such as Ti, Mg, Pd, or TiCo can be used. By exposing these metals to a high temperature atmosphere of hydrogen at about 300 ° C. to 1000 ° C. for a certain period of time and performing a hydrogen annealing treatment, it is possible to obtain a metal absorbing a certain amount of hydrogen. In addition, since it is exposed to various heat treatment conditions in the CRT manufacturing process, a material configuration and a process treatment condition capable of maintaining the performance under these high heat environments are appropriately set. Specifically, the partial pressure of hydrogen, which is a reducing gas released from the hydrogen storage metal, is always 3 times the partial pressure of the oxidizing gas (H ₂ O, O ₂ , CO _2, etc.) in the CRT. By setting the value to about twice to about ten times, it is possible to always keep the inside of the CRT in a reducing gas atmosphere. Further, as described in the present embodiment, among the components of the electron gun, at least one of the grid electrodes G1 to G5 constituting the cathode structure 52 or the electron lens portion 53 has a hydrogen storage function. Since hydrogen is produced using the hydrogen storage metal, the released hydrogen always exists near the emitter (cathode). As a result, the effect of preventing oxidation of the emitter is further enhanced, and more stable cathode operation can be expected.

In the first embodiment, the structure in which the surface layer of the electron emission region of the emitter of the field emission type electron source element is doped with hydrogen to effectively prevent the oxidation of the emitter surface has been described. It was confirmed that the same anti-oxidation effect as that of the first embodiment can be obtained with the apparatus. Also, in the current stability evaluation experiment by continuous operation as performed in the first embodiment, the field emission type electron source element is formed by setting the inside of the CRT to a reducing gas atmosphere using the hydrogen storage metal of the present embodiment. It has been confirmed that stable electron emission can be obtained over a long period of time from the emitter of the present invention.

As shown in FIG. 6, it is also effective to provide a heater 54 as a mechanism capable of heating the vicinity of the cathode to a constant temperature in a part of the cathode structure 52. Further, as shown in FIG. 7, the same heat treatment can be performed by providing the heater 54 as a configuration capable of heating the cathode from the outside after manufacturing the CRT. With these heating mechanisms, the hydrogen stored in the hydrogen storage metal can be efficiently released to the vicinity of the cathode, and the reducing atmosphere near the cathode can be more effectively maintained. Performing the heat treatment not only promotes the release of hydrogen from the hydrogen storage metal, but also enhances the surface cleaning action of the field emission electron source element itself. Further, the effect of recovering the emission performance can be expected by removing the adsorbed gas components such as the oxygen element and the carbon element temporarily attached to the emitter surface by the operation in the CRT by the heat treatment.

In this embodiment, an example in which a hydrogen storage metal is directly used as the material of the cathode structure forming the electron gun has been described. However, the hydrogen storage metal is formed on the surface of a general electron gun member used conventionally. Similar effects can be obtained by coating the material.

In the present embodiment, the size of each part of the image display device or the electron gun and the method of manufacturing each part are not particularly limited, and can be appropriately selected.

In the present embodiment, a typical cathode ray tube (CRT) has been described as an example of the application of the image display device. However, the application is not limited to the cathode ray tube. It can also be applied to a light-emitting display tube for lighting.

As described above, according to the image display device of the present embodiment, by controlling the atmosphere in the vacuum vessel of the CRT to an atmosphere having a reducing effect on the material of the emitter of the electron gun, the surface of the emitter (cathode) is controlled. Oxidation can be effectively prevented, so that stable electron emission performance can be maintained and a great effect is obtained for long life operation and stable operation.

Further, when the field emission type electron source element used in the first embodiment is used as the field emission type electron source element of the electron gun used in this embodiment, the effect described in the present embodiment is further enhanced, and a more desirable effect is obtained. You can expect it.

As described above, the field emission type electron source device of the present invention provides an emitter (cathode) by doping the surface layer of the electron emission region of the emitter with at least one reducing element selected from hydrogen and carbon monoxide. Since it is possible to effectively prevent the surface from being oxidized, it is possible to provide a cathode ray tube (CRT), an electron gun, and the like having stable electron emission performance.

Further, since the image display device of the present invention includes means for controlling the atmosphere in the vacuum vessel to an atmosphere having a reducing action on the material of the emitter of the electron gun, a field emission type used as a cathode of the electron gun is provided. It is possible to effectively prevent performance deterioration due to oxidation of the electron source element, and to provide a CRT display or the like having a large effect on long life operation and stable operation.

FIG. 1 is a cross-sectional view illustrating an example of a field emission type electron source device of the present invention. It is sectional drawing which shows an example of the process of manufacturing the field emission type electron source element of this invention. FIG. 9 is a diagram showing the relationship between the elapsed time and the emission current of the field emission electron source devices of the example and the comparative example. FIG. 2 is a cross-sectional view illustrating an example of the image display device of the present invention. FIG. 2 is a schematic sectional view illustrating an example of an electron gun used for the image display device of the present invention. FIG. 9 is a schematic sectional view showing another example of the electron gun used for the image display device of the present invention. It is sectional drawing which shows another example of the image display device of this invention. FIG. 2 is a cross-sectional view of a field emission light emitting device using a conventional field emission electron source device.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 11 Cathode substrate 12 Opening 13 Insulating layer 14 Leader electrode 15 Emitter 16 Surface layer

Claims (14)

A field emission electron source element including a cathode substrate, an insulating layer formed on the cathode substrate and having an opening, a lead electrode formed on the insulating layer, and an emitter formed in the opening. So,
A field emission type electron source device, wherein a surface layer of an electron emission region of the emitter is doped with at least one reducing element selected from hydrogen and carbon monoxide. The field emission electron source device according to claim 1, wherein the emitter is formed of a material containing silicon. The field emission electron source device according to claim 1, wherein the emitter is formed of a metal, and a thin film containing silicon is formed on a surface of the metal. 4. The field emission type electron source device according to claim 1, wherein the thickness of the surface layer is 5 nm or more and 30 nm or less. (5) The field emission type electron source device according to any one of (1) to (4), wherein the reducing element is doped by an ion doping method. (5) The field emission electron source device according to any one of (1) to (4), wherein the reducing element is doped by a plasma doping method. An image display device comprising the field emission type electron source device according to any one of claims 1 to 6. An image display device comprising: a vacuum container; an electron gun disposed in the vacuum container; means for deflecting an electron beam emitted from the electron gun; and a phosphor layer provided at a position facing the electron gun. And
The electron gun includes the field emission type electron source device according to any one of claims 1 to 6,
An image display apparatus comprising: means for controlling an atmosphere in the vacuum vessel to an atmosphere having a reducing action on a material of an emitter of the field emission electron source element. An image display device comprising: a vacuum container; an electron gun disposed in the vacuum container; means for deflecting an electron beam emitted from the electron gun; and a phosphor layer provided at a position facing the electron gun. And
The electron gun includes a field emission type electron source element having an emitter,
An image display device comprising means for controlling an atmosphere in the vacuum vessel to an atmosphere having a reducing action on a material of the emitter. The image display device according to claim 9, wherein the means for controlling the atmosphere having the reducing action is made of a material containing a hydrogen storage material. 11. The image display device according to claim 10, wherein a heating unit is further provided near the material containing the hydrogen storage material. 12. The image display device according to claim 10, wherein the hydrogen storage material is a material containing at least one selected from carbon nanotubes, graphite nanofibers, and other carbon materials. The image display device according to claim 10, wherein the material containing the hydrogen storage material is a conductive material provided in the vacuum vessel. 11. The image display device according to claim 10, wherein the material including the hydrogen storage material forms a grid electrode of the electron gun.

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