JP3250719B2 - Cathode for vacuum tube and field emission display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a diode, a triode,
Vacuum tube cathodes and field emission display devices used for vacuum tubes such as multipole tubes, fluorescent lamps, field emission display devices, electron microscopes, etc.
About the installation .

[0002]

2. Description of the Related Art A vacuum tube in which an electron flow flows from a cathode to an anode under a vacuum atmosphere or a reduced pressure atmosphere filled with an inert gas includes:
Starting from a diode with a hot cathode and an anode, a triode with one grid added to the diode, a multi-electrode with two or more grids added to the diode, a fluorescent display, an electron microscope, and a field emission display ( Hereinafter, it is referred to as “FED”.
Is an abbreviation for Field Emission Display). Such a vacuum tube generally uses a cathode made of a high melting point metal such as W, Mo, Ta, or the like, or a metal such as Ni. The cathode made of these metals functions as a hot cathode that emits electrons when heated.

Here, as a cathode used in a vacuum tube, it is important how to increase the electron emission efficiency of the cathode itself. In other words, if the electron emission efficiency from the cathode is low, it is necessary to apply a higher voltage accordingly, and thus there are problems such as an increase in power consumption and a reduction in the life of the cathode due to repeated application of an excessive voltage. In order to solve these problems, it is necessary to increase the electron emission efficiency of the cathode so that electrons can be effectively emitted from the cathode at a lower voltage.

Therefore, in the above hot cathode, BaO,
Electron emission efficiency has been improved by forming a film made of a material having a low work function, such as an oxide of an alkaline earth metal such as SrO or CaO, on the cathode surface. However, although the oxide film such as BaO formed on the surface of the cathode is porous, the oxide film is densified due to a sinter phenomenon due to heating during thermionic emission, resulting in a significant decrease in electron emission efficiency. Problem. Further, since the metal of the cathode material and the oxide film formed on the surface thereof have different thermal expansion coefficients, there is also a problem that the oxide film is peeled off from the cathode surface due to repetition of the cooling / heating cycle.
Furthermore, when used in a state with a low degree of vacuum, there is a problem that the surface shape of the electrode is sputtered by cations and the electron emission efficiency is reduced. In addition, there is a problem that the heating of the cathode requires a large amount of energy consumption, and the heating shortens the life of the cathode.

On the other hand, in recent years, in fields such as the FED or an electron microscope, conical and Spindt (Spindt) type cold cathode having a sharp tip made of Mo or the like, W, on the surface of the single crystal and W such as LaB ₆ Needle-shaped cold cathodes coated with Cs have been put to practical use. In such a cold cathode, since the electric field is concentrated at the tip and electrons are easily emitted, electrons are efficiently emitted from the tip by applying a high voltage without heating or slightly heating. be able to.

However, such Spindt-type or needle-shaped cold cathodes have the advantage that they consume less energy and have a longer life than hot cathodes. In addition, there is a problem that a structure for performing the process is required, and that a processing technique for forming a cone or a needle or the like requires advanced technology. In addition, there is also a problem that the effect of sputtering by cations is large, and if the sharp tip is rounded by sputtering, the electron emission efficiency is sharply reduced.

As described above, the hot cathode in which the film made of a material having a low work function is formed on the cathode surface and the cold cathode such as Spindt type have their own problems. And diamond-like carbon (hereinafter, referred to as “DL”) as an electron emitter having a negative electron affinity on the cathode surface.
C ". In addition, DLC is Diamond Lik.
In recent years, attention has been paid to films formed by e. The cathode provided with the DLC film can be used as a cold cathode, and therefore does not cause a problem specific to a hot cathode. Since the DLC film is a dense and strong film, stable electron emission can be expected for a long time, and even when used in a low vacuum state, there is a possibility that the electron emission efficiency is reduced due to sputtering by cations. Few. In addition, since it is not necessary to form a conical shape and sharpen the tip, the processing is easy, and a device for applying an ultra-high voltage is not required.

[0008]

However, the above D
Even with a cathode having an LC film, further improvement in electron emission efficiency is desired. The present invention has been made in view of the above circumstances, and has as a technical problem to be solved to further improve the electron emission efficiency in a vacuum tube cathode.

[0009]

Means for Solving the Problems (1) The cathode for a vacuum tube according to the first aspect of the present invention is provided to face the anode electrode in the vacuum tube, and is formed on the cathode electrode and the surface of the cathode electrode. in the negative vacuum tube for cathode made of an electron emitting member having an electron affinity for emitting electrons toward the anode electrode, the cathode electrode is the electron-emitting body shape
Higher melting point metal than melting point
In addition, between the cathode electrode and the electron emitter, an intermediate layer comprising a component constituting the cathode electrode and a component constituting the electron emitter is formed.

In this cathode for a vacuum tube, an intermediate layer composed of a component constituting the cathode electrode and a component constituting the electron emitter is formed between the cathode electrode and the electron emitter. The presence facilitates the transfer of electrons from the cathode electrode to the electron emitter. As a result, the amount of electrons supplied to the electron emitter increases, and the efficiency of emitting electrons from the electron emitter improves.

In addition, the presence of an intermediate layer composed of a component constituting the cathode electrode and a component constituting the electron emitter,
The adhesion between the cathode electrode and the electron emitter is improved, and the durability to the thermal cycle is improved. In a preferred embodiment
The intermediate layer has a thickness of 0.1 to 10 μm. Suitable
In the aspect, the shape of the cathode electrode is linear or band-like.
It is. In a preferred embodiment, the above-mentioned cathode electrode
The surface on the back side with respect to the anode electrode has an insulating layer
And a back electrode is provided .

If a back electrode is provided on the back surface of the cathode electrode with respect to the anode electrode via an insulating layer, a voltage lower than the voltage applied to the cathode electrode with a negative voltage is applied to the back electrode. Thereby, electron emission from the electron emitter toward the anode electrode can be promoted. Thereby, the electron emission efficiency from the electron emitter is improved. (2) The field emission display device according to claim 5, wherein the anode electrode and the cathode electrode are disposed opposite to each other at a predetermined interval, and the phosphor formed on a surface of the anode electrode facing the cathode electrode; A field emission type display device having a cathode electrode and an electron emitter having a negative electron affinity formed on a surface of the cathode electrode facing the anode electrode, wherein the cathode is provided between the cathode electrode and the electron emitter. An intermediate layer comprising a component constituting an electrode and a component constituting the electron emitter is formed, and an intermediate layer is formed on the cathode electrode with respect to the anode electrode.
A back electrode is provided on the back surface through an insulating layer.
It is characterized by having been done.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) The cathode for a vacuum tube according to claim 1, which is disposed in the vacuum tube so as to face the anode electrode, the cathode electrode, an electron emitter for emitting electrons toward the anode electrode, the cathode electrode and the electron emitter. And an intermediate layer formed of a component constituting the cathode electrode and a component constituting the electron emitter.

The material of the cathode electrode is an electron emitting material.
High melting point metal with a melting point higher than the reaction temperature
You. For example, high melting point metals such as W, Mo, Ta, and the like, and metals such as Ni, which are used as general hot cathode materials can be used. However, in order to prevent the cathode electrode material from melting when the electron emitter is formed on the surface of the cathode electrode, a melting point higher than the reaction temperature at the time of forming the electron emitter, specifically, a melting point of 800 ° C. or more is required. It is necessary to have a metal. Further, from the viewpoint of improving the adhesion between the electron emitter and the cathode electrode via the intermediate layer, it is preferable to use one having high reactivity with the components constituting the electron emitter. For example, when crystalline diamond or DLC is used as an electron emitter as described later, a material having high reactivity with C (carbon) as a component constituting the electron emitter, that is, W, Mo, Ta, or the like is used. Preferably, it is used.

The shape of the cathode electrode is not particularly limited, and may be a linear shape, a band shape, or a planar shape such as a flat plate shape. In addition, from the viewpoint of uniformly dispersing the electron emission positions from the cathode electrode, it is preferable to provide the convex corner portions on the surface of the cathode electrode so as to be evenly dispersed at as small an interval as possible. By uniformly dispersing the convex corners on the surface of the cathode electrode as described above, the surface of the electron emitter formed on this surface also has the same shape. Electron emission can be concentrated by concentrating the electric field at the corner, and electron emission from the electron emitter can be stably and uniformly dispersed for a long time.

As the material of the electron emitter, a material having a negative electron affinity and capable of emitting electrons by applying a voltage to the cathode electrode, for example, DLC or crystalline diamond can be used. However, from the viewpoint that the electron emission capability is high and the driving voltage can be reduced, it is preferable to use DLC. The thickness of the electron emitter is 1 to 30 μm.
Degree.

The intermediate layer comprising the components constituting the cathode electrode and the components constituting the electron emitter can be formed simultaneously with the formation of the electron emitter on the surface of the cathode electrode. The lower limit of the thickness of the intermediate layer is preferably 0.01 μm, particularly preferably 0.1 μm. If the thickness of the intermediate layer is less than 0.01 μm, the effect of improving the electron emission efficiency and the adhesion by the intermediate layer can hardly be expected. This is because the effect of improving the performance can be expected. On the other hand, if the thickness of the intermediate layer is a certain thickness or more, the effect of improving the electron emission efficiency and the adhesion by the intermediate layer can be further expected. The upper limit of the thickness is preferably 100 μm, particularly preferably 10 μm.

The intermediate layer and the electron emitter formed on the surface of the cathode electrode are formed on the entire surface of the cathode electrode, or a mask having a predetermined shape is formed by using a photoresist to form a dry etching method or a chemical etching method. It can be partially formed by patterning into a predetermined shape by a method or the like. Further, an insulating layer can be provided on the opposite side of the cathode electrode facing the anode electrode.

The cathode for a vacuum tube of the present invention can be manufactured as follows. First, a linear or planar cathode electrode is prepared, and if necessary, the surface of the cathode electrode is polished with a diamond paste or the like, so that a fine and uniform uneven shape is obtained. Next, an ion beam deposition method in which a + ion beam of carbon formed by accelerating an ionized carbon atom by an electric field is applied to the surface of the cathode electrode, and a graphite target is irradiated with a pulsed laser, and the evaporated and vaporized emitted carbon atoms are converted into a cathode electrode. Laser deposition method to deposit as diamond on the surface, or decomposition and excitation by heat or discharge to activate a mixed gas obtained by diluting a gas containing carbon atoms such as methane (or acetylene, carbon monoxide, ethyl alcohol, acetone) with hydrogen An atmosphere is formed, and a cathode electrode heated to 600 to 1200 ° C. is placed in the active atmosphere to deposit diamond on the surface thereof. An electron emitter is formed on the surface of the substrate. The above CVD
The energy source in the method is a hot filament (2
Tungsten heated to over 000 ° C), microwave,
High frequency, arc discharge, DC / AC arc discharge, combustion flame using an acetylene gas welding torch, and the like can be adopted.

The intermediate layer provided between the cathode electrode and the electron emitter can be formed simultaneously with the formation of the electron emitter on the surface of the cathode electrode. That is,
Reaction conditions for forming the electron emitter, for example, reaction time,
By appropriately setting the reaction temperature and the like, an intermediate layer having a predetermined thickness can be formed. However, due to the usual method of manufacturing an electron emitter that heats the cathode electrode from the outside,
If an attempt is made to form an intermediate layer having a thickness of 0.01 μm or more, in which the effects of improving electron emission efficiency and adhesion can be expected, there is a problem that the reaction time becomes extremely long. Therefore, the cathode electrode is energized from a DC or AC power supply, and while the cathode electrode is internally heated by resistance heating,
It is preferable to adopt a method of forming an electron emitter on the surface of the cathode electrode. According to this method, since the cathode electrode is heated from the inside, the reaction between the components constituting the cathode electrode and the components constituting the electron-emitting body is promoted very effectively, and the case where the cathode electrode is heated from the outside is considered. In comparison, the intermediate layer can be formed in a shorter time.

Here, conditions of a preferred embodiment for simultaneously forming the electron emitter and the intermediate layer made of crystalline diamond on the surface of the cathode electrode by using the plasma CVD method will be described. Raw material: methane gas and hydrogen gas (methane gas concentration: 0.1
1 to 30%) Reaction pressure: 1 to 30 after exhausting to 10 ^-7 Torr or less once
Adjusted to 0 Torr Heating temperature by energizing the cathode electrode: 500-200
0 ° C. Bias voltage: −1 to 300 V Reaction time: 1 to 60 minutes The conditions of a preferred embodiment for simultaneously forming an electron emitter made of DLC and an intermediate layer on the surface of a cathode electrode using a plasma CVD method are as follows. Shown in

Raw materials: methane gas and hydrogen gas (methane gas concentration: 1 to 5%) Reaction pressure: 50 to 200 Torr Heating temperature by energizing the cathode electrode: 750 to 850
C. Bias voltage: 50 to 200 V Reaction time: 3 to 10 minutes As described above, an intermediate layer composed of a component constituting the cathode electrode and a component constituting the electron emitter is formed between the cathode electrode and the electron emitter. This facilitates the transfer of electrons from the cathode electrode to the electron emitter through the intermediate layer, and increases the amount of electrons supplied to the electron emitter, so that the efficiency of electron emission from the electron emitter can be improved.

Further, the presence of an intermediate layer composed of a component constituting the cathode electrode and a component constituting the electron emitter,
Since the adhesion between the cathode electrode and the electron emitter is improved,
The durability to the cooling / heating cycle can be improved. Furthermore, since DLC or crystalline diamond is used as the electron emitter, the cathode for a vacuum tube can be used as a cold cathode, and therefore, there is no problem peculiar to a hot cathode. Since the electron emitter made of DLC or crystalline diamond is a dense and strong film, stable electron emission can be expected for a long time, and it is sputtered by cations even when it is used in a low vacuum state. The electron emission efficiency is less likely to be reduced. In addition, since there is no need to sharpen the tip by processing into a cone or the like, processing is easy,
There is no need for a device for applying an ultra-high voltage. Furthermore, DL
Electron emitters composed of C or crystalline diamond have good thermal conductivity, can make the temperature of the electrode surface uniform in a short time, and are black or gray and have no metallic luster and are inconspicuous, which is advantageous for application to displays and the like. Become.

In a preferred embodiment, the cathode electrode
An insulating layer is provided on the back surface of the anode electrode.
A back electrode is provided through the intermediary.

The material of the insulating layer is not particularly limited as long as it can insulate between the cathode electrode and the back electrode, and SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , AlN and the like can be used. It is preferable that the thickness of the insulating layer be as thin as possible within a range that allows sufficient insulation between the cathode electrode and the back electrode. Specifically, 0.1 to 1
It is preferably about μm, and particularly preferably about 0.1 to 0.5 μm. The thickness of the insulating layer is 0.1μ
When the thickness is smaller than m, defects such as pinholes are likely to occur in the insulating layer, and it becomes difficult to secure sufficient insulating properties. On the other hand, if the thickness of the insulating layer exceeds 1 μm, the insulating layer is likely to be separated from the cathode electrode due to stress at the time of heating, and it is necessary to increase the applied voltage to the back electrode as the insulating layer becomes thicker. This leads to an increase in power consumption.

The material of the back electrode is not particularly limited, and metals such as Au, Ag, Cu, Al, and Mg can be used. The shape of the back electrode can be appropriately determined according to the shape of the cathode electrode. That is, if the cathode electrode is flat, the back electrode can also be flat, and if the cathode electrode is linear, a C-shape or U-shape with a substantially uniform thickness along the linear outer peripheral surface. It may have a concave shape extending substantially half way around the character. In addition, the thickness of the back electrode can be about 0.1 to 1.0 μm.

As described above, the back electrode is provided on the surface on the back side of the cathode electrode with respect to the anode electrode via the insulating layer.
By applying a voltage lower than the voltage applied to the cathode electrode with a negative voltage to this back electrode, to create an electric field that pushes electrons to the surface of the electron emitter opposite to the back electrode, that is, the side facing the anode electrode. In addition, electron emission from the electron emitter can be promoted. Thereby, the electron emission efficiency from the electron emitter is improved.

Further, in the cathode for a vacuum tube, the cathode electrode and the back electrode are provided integrally with an insulating layer interposed therebetween, so that the handling is facilitated. In addition, the distance between the cathode electrode and the back electrode can be reduced as much as possible while preventing short-circuit between the two. It can be improved very effectively.

(2) The cathode for a vacuum tube according to claims 1 to 4 can be suitably used for a fluorescent display tube, an electron microscope, an FED, etc., in addition to a diode tube, a triode tube and a multi-pole tube. A field emission display (FED) according to claim 5.
Are formed on an anode electrode and a cathode electrode opposed to each other at a predetermined interval; a phosphor formed on a surface of the anode electrode facing the cathode electrode; and a phosphor formed on a surface of the cathode electrode facing the anode electrode. In an FED provided with an electron emitter having a negative electron affinity, a component constituting the cathode electrode and a component constituting the electron emitter are provided between the cathode electrode and the electron emitter. An intermediate layer is formed, and the cathode electrode corresponds to the anode electrode.
A back electrode is provided on the back surface through an insulating layer.
It is characterized by having been done.

[0030]

In this FED, for example, a transparent face substrate serving as a display surface and a back substrate are disposed to face each other, and a spacer made of a resin mixed with silica or resin beads is provided around both substrates to provide a space between the two substrates. The gap can be maintained at about 5 to 50 μm, and a space can be formed inside, and the space can be evacuated to about 10 ⁻⁶ to 10 ⁻⁷ Torr. Then, one of the anode electrode and the cathode electrode is formed on the surface of the transparent face substrate facing the back substrate, and the other of the anode electrode and the cathode electrode is formed on the surface of the back substrate facing the transparent face substrate. In addition, a phosphor can be formed on the surface of the anode electrode facing the cathode electrode, and an electron emitter having a negative electron affinity can be formed on the surface of the cathode electrode facing the anode electrode. In addition, the thickness of the transparent face substrate and the back substrate is 0.5 to 3 mm.
Degree. Further, the gap between the anode electrode and the cathode electrode is appropriately set in accordance with the threshold value of the electron emitter and the magnitude of a drive voltage of a drive IC for applying a voltage to the FED.

As a method for evacuating the internal space surrounded by the transparent face substrate, the back substrate, and the spacer, for example, a glass tube for evacuation is drawn from the back substrate, and after evacuation from the glass tube, A method of fusing the glass tube or the like can be adopted. If necessary, a ring-shaped metal (magnesium, barium, or the like) called a getter is placed inside the vacuum structure, and the metal is evaporated by high-frequency heating during or after evacuation or sealing. Also, the degree of vacuum in the vacuum structure can be increased.

The anode electrode is a transparent electrode when located on the display surface side of the FED, and can be a normal metal electrode or a transparent electrode when located on the opposite side to the display surface. As the transparent electrode, ITO thin film, SnO ₂ thin film, I
An n ₂ O ₃ thin film, an In ₂ O ₃ —SnO ₂ thin film, or the like can be used, and a metal electrode can be an Al thin film, a Cu, Ti, Cr thin film, or the like. The thickness of the anode electrode is 0.1 to
It can be about 2 μm.

The phosphor formed on the surface of the anode electrode facing the cathode electrode is Zn, which emits green light.
O: Zn, ZnS: M that emits amber (amber) color
n or the like can be adopted. The phosphor can be uniformly applied at a rate of 1 to 10 mg / cm ² by a sedimentation method or the like. According to the FED of the fifth aspect, since the electron emission efficiency from the electron emitter is improved, many electrons can be emitted from the electron emitter at a low voltage.
It is possible to reduce the power consumption, improve the emission luminance, and extend the life of D.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a cathode for a vacuum tube and a field emission type of the present invention will be described.
Examples of the display device will be described more specifically. (Example 1) In this example, the cathode for a vacuum tube according to claim 1 is applied to an FED. As shown in the schematic sectional view of FIG. 1, the FED includes a transparent face glass substrate 1 serving as a display surface,
A back glass substrate 2 disposed opposite to the transparent face glass substrate 1 at a predetermined interval, and a spacer made of a resin mixed with silica or resin beads for sealing around the transparent face glass substrate 1 and the back glass substrate 2. 3 forms a vacuum space inside. The transparent face glass substrate 1 and the back glass substrate 2
Both are made of soda-lime glass having a thickness of 1.1 mm. Further, the FED draws a glass tube for evacuation from the back glass substrate 2, evacuates the glass tube, and melts the glass tube to obtain 10 ^-6 T.
The vacuum degree is orr.

A transparent anode electrode 4 is formed on the inner surface of the transparent face glass substrate 1, and a vacuum tube cathode 6 is provided on the inner surface of the back glass substrate 2 via a lead electrode 5. A phosphor 7 is formed on a surface of the transparent anode electrode 4 facing the vacuum tube cathode 6. The gap between the transparent anode 4 and the vacuum tube cathode 6 is 10 μm.

The transparent anode electrode 4 is made of an ITO thin film having a thickness of 0.2 μm formed by sputtering. The phosphor 7 is made of ZnO: Zn which emits green light formed by a precipitation method, and has a thickness of 10 μm. As shown in FIG. 2, the vacuum tube cathode 6 includes a linear cathode electrode 61, and an electron emitter 62 having a negative electron affinity and formed over the entire outer peripheral surface of the cathode electrode 61 with a substantially uniform thickness. And an intermediate layer 63 formed between the cathode electrode 61 and the electron emitter 62. And
The cathode electrode 61 is made of a tungsten wire having a diameter of φ0.5 mm, the electron emitter 62 is made of crystalline diamond, and the intermediate layer 63 is made of carbon as a compound formed by reacting carbon, which is a component of diamond, with tungsten. It is made of tungsten (WC or W ₂ C). Note that the thickness of the electron emitter 62 is 0.5 μm, and the thickness of the intermediate layer 63 is 1.0 μm.

The cathode 6 for a vacuum tube was manufactured by an apparatus schematically shown in FIG. This device comprises a cathode electrode 61
Reels 10 and 11 for feeding and winding
, A diamond thin film forming apparatus 12, a cathode electrode 6
The power supply 13 supplies an AC or DC current to the power supply 1. That is, in this device, one reel 10
, A linear cathode electrode 61 is continuously fed into the diamond thin film forming apparatus 12. The cathode electrodes 6 on the upstream and downstream sides of the diamond thin film forming apparatus 12
Power supply 1 via current supply line 14 connected to power supply 1
The cathode 6 for a vacuum tube is manufactured by forming an electron emitter 62 and an intermediate layer 63 made of crystalline diamond on the surface of the cathode electrode 61 by the diamond thin film forming device 12 while supplying a current to the cathode electrode 61 from 3. The cathode 6 for a vacuum tube after manufacture is wound up on the other reel 11.

In this embodiment, the diamond thin film forming apparatus 1
As No. 2, a plasma CVD apparatus was used. The film forming conditions in this plasma CVD apparatus are as follows. The reaction time can be adjusted by adjusting the feeding and winding speed of the cathode electrode 61 by the reels 10 and 11. In addition, the tungsten wire as the cathode electrode 61 was previously polished with a diamond paste.

Raw material: methane gas and hydrogen gas (methane gas concentration: 3%) Reaction pressure: once evacuated to 10 ^-7 Torr or less, then 100 T
Heating temperature by energizing the cathode electrode: 800 ° C. Bias voltage: 120 V Reaction time: 5 minutes In the FED having the above configuration, a predetermined electric field is applied between the transparent anode electrode 4 and the vacuum tube cathode 6 from a driving power source (not shown). Then, electrons are efficiently emitted from the electron emitters 62 of the vacuum tube cathode 6, and the electrons collide with the phosphor 7, whereby the phosphor 7 emits light of a predetermined color. And the image is transmitted through the transparent face substrate 1.

According to this FED, the intermediate layer 63
, The electron emission efficiency from the electron emitter 62 is improved, so that more electrons can be emitted from the electron emitter 62 at a lower voltage, and the power consumption in the FED is reduced, the emission luminance is improved, and It is possible to extend the life. (Evaluation) In the FED of Example 1, the voltage applied to the anode electrode 4 and the cathode 6 for the vacuum tube was variously changed, and the state of the change in the electron current emitted from the electron emitter 62 was examined.
For comparison, Comparative Example 1 using a vacuum tube cathode made of a tungsten wire instead of the vacuum tube cathode 6 of Example 1 above.
And the FED of Comparative Example 2 using a vacuum tube cathode comprising a cathode electrode 61 and an electron emitter 62 instead of the vacuum tube cathode 6 of Example 1 described above. FIG. 4 shows the results. The cathode for a vacuum tube according to Comparative Example 2 was manufactured in the same manner and under the same conditions as in Example 1 except that the cathode electrode 61 was not electrically heated.

As is apparent from FIG. 4, the electron emission voltage can be reduced from about 1300 V to about 400 V by forming the electron emitter 62 made of crystalline diamond on the surface of the cathode electrode 61 made of a tungsten wire. Also, by forming the intermediate layer 63 between the cathode electrode 61 and the electron emitter 62, the electron emission voltage could be further reduced to 300V.

(Embodiment 2) In a vacuum tube cathode 6 according to the present embodiment shown in FIG. 5, a ridge 61a having a triangular cross section extending in the circumferential direction is formed on the surface of the cathode electrode 61 at equal intervals in the axial direction. They are provided in a uniformly dispersed manner. The height of the ridges 61a is about 50 μm, and the interval between the ridges 61a is about 150 μm.
It is. Other configurations are the same as those in the first embodiment.

Since the projection 61 a is formed on the surface of the cathode electrode 61, the surface of the electron emitter 62 formed on this surface also has the same unevenness as the cathode electrode 61. Then, the ridges 6 of the electron emitting body 62
Since the electric field is concentrated on the tip of 1a, that is, the convex streak, and electrons are intensively emitted therefrom, the electron emitter 6
2 can be uniformly dispersed.

(Embodiment 3) A cathode 6 for a vacuum tube according to the present embodiment shown in FIG. 6 has convex ridges 61b having a rectangular cross section extending in the circumferential direction on the surface of the cathode electrode 61 at equal intervals in the axial direction. They are provided in a uniformly dispersed manner. The height of the ridges 61b is about 50 μm, and the interval between the ridges 61b is about 150 μm.
It is. Other configurations are the same as those in the first embodiment.

Since the projection 61 ba is formed on the surface of the cathode electrode 61, the surface of the electron emitter 62 formed on this surface also has the same concavo-convex shape as the cathode electrode 61. Then, the electric field is concentrated on the protruding ridges of the protruding ridges 61b of the electron emitter 62, and the electrons are intensively emitted therefrom, so that the electron emission from the electron emitter 62 can be uniformly dispersed. Becomes

(Embodiment 4) The vacuum tube cathode 6 according to the present embodiment shown in FIG.
Only the electron emitter 62 formed on the outermost surface is patterned, and the electron emitter 62 is formed in a circular shape only on the surface of the cathode electrode 61 facing the anode electrode 4. This is because after manufacturing the cathode 6 for a vacuum tube of the first embodiment,
It is manufactured by applying a resist in a circular shape to a portion of the surface of the electron emitter 62 where the electron emitter 62 is desired to be left, and removing the electron emitter 62 where the resist is not applied by dry or chemical etching. The circular diameter of the electron emitter 62 is about 30 μm.
The interval between the two is about 100 μm. Other configurations are the same as those in the first embodiment.

Since the electron emitters 62 are partially formed as described above, the electric field is concentrated on the convex corners of each electron emitter 62, so that the electron emission can be concentrated. Further, since the electron emitters 62 are uniformly dispersed, the electron emission can be uniformly dispersed. (Embodiment 5) Cathode 6 for vacuum tube according to this embodiment shown in FIG.
In the fourth embodiment, the intermediate layer 63 in a portion where the electron emitter 62 is not provided in the fourth embodiment is removed, and the other configuration is the same as that of the first embodiment. This means that, in advance, a heat-resistant oxide film or the like is formed on the surface of the tungsten wire serving as the cathode electrode 61, and the oxide film or the like where the electron emitter 62 and the intermediate layer 63 are to be formed is removed by etching. A cathode for a vacuum tube is produced from the cathode electrode 61 thus treated in the same manner as in the first embodiment, and then an oxide film or the like is melted and removed, thereby producing the cathode.

(Embodiment 6) The cathode 6 for a vacuum tube according to this embodiment shown in FIG. 9 is obtained by patterning the electron-emitting body 62 in Embodiment 4 so as to form a strip extending in the circumferential direction. Is similar to that of the first embodiment. (Embodiment 7) The vacuum tube cathode 6 according to the present embodiment shown in FIG. 10 is the same as the embodiment 6 except that the intermediate layer 63 where the electron emitter 62 is not provided is removed. Other configurations are the same as those of the first embodiment.

(Embodiment 8) The cathode 6 for a vacuum tube according to this embodiment shown in FIG.
₂ ) forming an insulating layer 64 made on the surface of the electron emitter 62, and then partially removing the insulating layer 64 by etching;
The electron emitter 62 is exposed in a circular shape only on the surface of the cathode electrode 61 facing the anode electrode 4, and the other configuration is the same as that of the first embodiment. The insulating layer 6
4 has a thickness of about 0.2 μm.

(Embodiment 9) The vacuum tube cathode 6 according to the present embodiment shown in FIG.
Is obtained by etching and removing the insulating layer 64 so as to appear in a strip shape extending in the circumferential direction. The other configuration is the same as that of the first embodiment. (Embodiment 10) A vacuum tube cathode 6 according to this embodiment shown in FIG. 13 has an electron emitter 62 and an intermediate layer 63 formed only on the surface side of a cathode electrode 61 facing the anode electrode 4. The configuration is the same as in the first embodiment. This was manufactured by forming a vapor deposition film only from a specific direction.

In this vacuum tube cathode, the cathode electrode 61
Since the cathode electrode 61 having a low electric resistance is exposed on the back side of the anode electrode 4, electrons are effectively supplied from this portion, and the cathode electrode 61 is exposed.
Electrons can be effectively emitted toward the anode electrode 4 from the electron emitters 62 formed on the front surface side facing the anode electrode 4.

(Embodiment 11) A vacuum tube cathode 6 according to this embodiment shown in FIG. 14 has an insulating layer 64 provided on the surface of an electron emitter 62 on the back side of the cathode electrode 61 with respect to the anode electrode 4. The other configuration is the same as in the first embodiment.
Is the same as (Embodiment 12) In a vacuum tube cathode 6 according to this embodiment shown in FIG. 15, an insulating layer 64 is formed on the surface of an electron emitting body 62 on the back side of a cathode electrode 61 with respect to an anode electrode 4, and this insulating layer A concave back electrode 65 having a uniform thickness and extending half a circumference in a C-shape along the linear outer peripheral surface is formed on the surface of the substrate 64, and the other configuration is the same as that of the first embodiment. . The insulating layer 64 is made of SiO ₂
And a thickness of about 0.2 μm. The back electrode 65 is made of Au and has a thickness of about 3 μm. This back electrode 65 was manufactured by patterning using a photoresist.

In the vacuum tube cathode 6, a negative voltage lower than the voltage applied to the cathode electrode 61 is applied to the back electrode 65, and the opposite side of the back electrode 65, that is, the side facing the anode electrode 4. By generating an electric field that pushes out electrons on the surface of the electron emitter 62, electron emission from the electron emitter 62 can be promoted. Thus, the efficiency of emitting electrons from the electron emitter 62 is improved.

In the vacuum tube cathode 6, since the cathode electrode 61 and the back electrode 65 are provided integrally with the insulating layer 64 interposed therebetween, the handling becomes easy. Further, the distance between the cathode electrode 61 and the back electrode 65 can be reduced as much as possible while preventing a short circuit between them. The release efficiency can be improved very effectively.

(Evaluation) In the FED of Example 12, while applying a voltage of 100 V to the back electrode 65, the voltage applied to the anode electrode 4 and the cathode 6 for the vacuum tube were variously changed, and the emission from the electron emitter 62 was performed. The state of the change in the electron current was examined. For comparison, the same test was performed for the case where no voltage was applied to the back electrode. Figure 1 shows the results.
6 is shown.

As is apparent from FIG.
By applying a voltage to, the electron emission voltage could be reduced. Since the insulating layer 64 has a sufficient withstand voltage, when the entire surface of the electron emitter 62 is covered with the insulating layer 64, no electrons are emitted even when a voltage of 1500 V is applied.

(Embodiment 13) In the vacuum tube cathode 6 of this embodiment shown in FIG. 17, an insulating layer 64 is formed on the surface of an electron emitter 62 on the back side of the cathode electrode 61 with respect to the anode electrode 4, and the insulating layer 64 is formed. On the surface of the insulating layer 64, a concave back electrode 65 having a uniform thickness and extending in a C-shape along a linear outer peripheral surface is formed, while a surface of the cathode electrode 61 facing the anode electrode 4 is formed. On the side, the electron emitter 62 is partially formed in a cone shape, and an insulating layer 64 is formed on the surface of the other portion of the electron emitter 62 so that the electron emitter 62 formed in the cone shape is exposed. The acceleration electrode 66 is formed through the intermediary of the second embodiment, and the other configuration is the same as that of the first embodiment. In addition, this cathode 6 for vacuum tubes is
After the cathode for a vacuum tube of Example 1 was manufactured, the cathode was manufactured using micromachining to which an advanced semiconductor process was applied.

In the cathode for a vacuum tube, an acceleration electrode 66 is also formed together with the back electrode 65, and furthermore, electrons are emitted from the tip of the electron emitter 62, which is formed in a cone shape and where the electric field is concentrated, so that the electron emission is extremely effective. Efficiency can be increased. Further, by changing the voltage applied to the acceleration electrode 66, the amount of electron emission from the electron emission pair 62 can be positively controlled.

(Embodiment 14) In the vacuum tube cathode 6 of this embodiment shown in FIG. 18, the cathode electrode 61 is made of a flat tungsten plate, and the surface of the cathode electrode 61 facing the anode electrode 4 has an electron emitting material. 62 and an intermediate layer 63 are formed, the electron emitter 62 is partially formed in a cone shape, and the surface of another portion of the electron emitter 62 is exposed so that the cone-shaped electron emitter is exposed. An acceleration electrode 66 is provided via an insulating layer 64, and a flat back electrode 65 is provided on the surface of the cathode electrode 61 on the back side of the anode electrode 4 via the insulating layer 64. This is similar to the first embodiment.

In the above embodiment, crystalline diamond is used as the electron emitter 62. However, DLC can be used instead of crystalline diamond.

[0062]

As described above in detail, in the vacuum tube cathode according to the first to fourth aspects, since the electron emission efficiency of the electron emitter is increased, many electrons are emitted from the electron emitter at a low voltage. It is possible to reduce the power consumption and extend the life of the vacuum tube. Claim 5
According to FED described, since the improved electron emission efficiency from the electron emitter can emit many electrons from the electron emitting member at a low voltage, reduction in power consumption in FED, the emission luminance It is possible to improve and extend the service life.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an FED according to a first embodiment.

FIG. 2 shows a cathode for a vacuum tube according to the first embodiment;
Is a longitudinal sectional view, and (b) is a transverse sectional view.

FIG. 3 is an explanatory view schematically showing a method of manufacturing the cathode for a vacuum tube according to the first embodiment.

FIG. 4 is a diagram showing a relationship between a voltage applied to a cathode and an anode and an electron current emitted from an electron emitter.

FIG. 5 is a longitudinal sectional view of a vacuum tube cathode according to the second embodiment.

FIG. 6 is a longitudinal sectional view of a vacuum tube cathode according to a third embodiment.

FIG. 7 shows a cathode for a vacuum tube according to Example 4;
Is a plan view, (b) is a longitudinal sectional view, and (c) is a transverse sectional view.

FIG. 8 is a longitudinal sectional view of a vacuum tube cathode according to a fifth embodiment.

FIG. 9 shows a cathode for a vacuum tube according to the sixth embodiment, wherein (a)
Is a plan view, (b) is a longitudinal sectional view, and (c) is a transverse sectional view.

FIG. 10 is a longitudinal sectional view of a vacuum tube cathode according to a seventh embodiment.

FIG. 11 shows a vacuum tube cathode according to the eighth embodiment,
(A) is a plan view, (b) is a longitudinal sectional view, and (c) is a transverse sectional view.

FIG. 12 shows a vacuum tube cathode according to the ninth embodiment;
(A) is a plan view, (b) is a longitudinal sectional view, and (c) is a transverse sectional view.

FIG. 13 shows a vacuum tube cathode according to the tenth embodiment;
(A) is a longitudinal sectional view, (b) is a transverse sectional view.

FIG. 14 shows a cathode for a vacuum tube according to Example 11;
(A) is a longitudinal sectional view, (b) is a transverse sectional view.

FIG. 15 shows a vacuum tube cathode according to Example 12;
(A) is a longitudinal sectional view, (b) is a transverse sectional view.

FIG. 16 is a diagram showing the relationship between the voltage applied to the cathode and anode electrodes and the electron current emitted from the electron emitter.

FIG. 17 shows a vacuum tube cathode according to Example 13;
(A) is a plan view, (b) is a longitudinal sectional view, and (c) is a transverse sectional view.

FIG. 18 shows a cathode for a vacuum tube according to Example 14;
(A) is a plan view, and (b) is a cross-sectional view taken along line AA of (a).

[Explanation of symbols]

1 is a transparent face glass substrate, 2 is a back glass substrate,
3 is a spacer, 4 is a transparent anode electrode, 5 is a lead electrode, 6 is a cathode for a vacuum tube, 7 is a phosphor, 61 is a cathode electrode, 62 is an electron emitter, 63 is an intermediate layer, 64 is an insulating film,
65 is a back electrode and 66 is an acceleration electrode.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-65701 (JP, A) JP-A-4-138636 (JP, A) JP-A-10-112257 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01J 1/304 H01J 9/02

Claims (5)

(57) [Claims] A cathode, and an electron emitter having a negative electron affinity formed on a surface of the cathode and emitting electrons toward the anode; In the vacuum tube cathode, the cathode electrode is made of a high melting point metal having a melting point higher than a reaction temperature at the time of forming the electron emitter, and the cathode electrode is formed between the cathode electrode and the electron emitter. A cathode for a vacuum tube, wherein an intermediate layer comprising a component and a component constituting the electron emitter is formed. 2. The vacuum tube cathode according to claim 1, wherein said intermediate layer has a thickness of 0.1 to 10 μm. 3. The cathode for a vacuum tube according to claim 1, wherein the shape of the cathode electrode is linear or band-like. 4. The cathode for a vacuum tube according to claim 1, wherein a back electrode is provided on a surface of the cathode electrode on a back side of the anode electrode with an insulating layer interposed therebetween. 5. An anode electrode and a cathode electrode which are disposed opposite to each other at a predetermined interval, a phosphor formed on a surface of the anode electrode facing the cathode electrode, and a surface of the cathode electrode facing the anode electrode. A field emission type display device provided with an electron emitter having a negative electron affinity formed on the cathode electrode, wherein a component constituting the cathode electrode and the electron emitter are provided between the cathode electrode and the electron emitter. an intermediate layer is formed consisting of the components constituting the above cathodic electrodeposition
The surface on the back side of the pole with respect to the anode electrode is insulated
A field emission display device comprising a back electrode provided via a layer .