JPH09245742A - Gas sealed electron flow electronic tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine shaped current electronic tube operating constantly for a long period of time. SOLUTION: An electrode tube 10 is made of an electron emission element 4 provided with an acute needle 3 which emits electrons as a cathode, a crystal electrode 7 as a plate, and a phosphor 6 on the inner face side thereof. Helium gas is sealed in an electronic tube 10 to prevent the acute needle 3 from being degraded by impure atom (molecule) produced from a tube wall or the like of the electrode tube 10. At this time, the relationship of λeg>d1 >λg≈λmg is met, where the average free course of electrons is λeg, the average free action of inactive gas atom (molecule) is λg, the average free course of impure atom (molecule) is λmg, and the distance between the acute needle 3 and the crystal electrode 7 is d1 .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas filled electron flow type electron tube, and more particularly to a microscopic electron tube in which electrons are stably emitted.

[0002]

2. Description of the Related Art Among electron tubes used by emitting free electrons from a cathode, a CRT (CRT) as a picture tube is widely used, and an LCD (liquid crystal display) is used.
It is superior in brightness and dot density to PDP (Plasma Display Panel) and PDP (Plasma Display Panel), but since the screen is formed by vertically and horizontally deflecting the electron beam, the driving voltage is extremely high and There is a limit to downsizing the shape. However, if this is miniaturized and a small flat display that uses one electron tube as one dot can be made, a wide variety of images can be displayed on one screen, and a large image can be displayed by combining them. It seems to have great practical significance, such as gaining benefits.

From such a viewpoint, an FED (Field Emission Display) has been proposed. That is, 10 ^-6 Tor
Under high vacuum of about r, pointed needle (curvature radius 10 nm-1 μm)
It is a display device which applies electrons to a high electric field and utilizes electrons emitted by the tunnel effect. FIG. 4 is a schematic partial cross-sectional view of the electron-emitting device 11 used therein. An emitter 12 having an emitter edge 12P at its tip is insulated and led out by silicon nitride 13, both sides of which are sandwiched by silicon oxide 14 as an insulating film, and silicon nitride 15 is further formed on both sides thereof. Further, a conductive emitter contact 16 is provided so as to penetrate the silicon nitride 15 and the silicon oxide 14 on one side, and the emitter 12 is sandwiched between the tip ends of the silicon nitride 15 on both sides, and the gate electrode 17 is provided so as to face each other. It is structured. The gap g between the lead-out portion of the emitter 12 and the silicon nitride 15 is 0.5 μm.

It is reported that a field emission current of 1 μA or more was obtained from the electron-emitting device 11 described above. Further, in another example, there is a report that a current of 1 μA was obtained by applying a voltage of 20V. This means that the above-mentioned electron-emitting device 11
It means that it is possible to cause the phosphor to emit light by the emitted electrons by incorporating the above as a cathode into the electron tube and providing the phosphor on the plate side as the anode.
In fact, it's already a 1 inch diagonal 50x50 cell monochrome F
The ED is being prototyped. Although it is said that there is a problem in the uneven brightness of each cell, the FED is 0.36 mm square per cell.

As described above, it has been pointed out that the electric current of the FED is unstable and that the pointed needle as the cathode is contaminated and deteriorated by the impurities detached from the inner wall of the electron tube and the phosphor. This is also considered to be one of the causes of destabilization.

On the other hand, as a flat display that utilizes the light emission associated with the gas discharge of the gas sealed in the electron tube, P
DP (plasma display panel) has already been put to practical use, and full-colorization is also in progress. FIG. 5 is a schematic partial sectional view of an AC type PDP 20, in which a rear glass substrate 21 has a column electrode 23 covered with a dielectric material 22,
A row electrode 25 covered with a dielectric 24 on its upper surface is provided, and a phosphor 28 is provided with a black barrier 29 on a lower surface of a front glass substrate 27 installed via a space 26 for enclosing helium gas. There is. Then, a voltage is applied between the column electrode 23 and the row electrode 25 to cause the helium gas to generate the discharge indicated by the broken line, and the phosphor 28 of the front glass substrate 27 is made to shine by the generated ultraviolet rays. This PDP2
0 has a defect that the driving voltage is as high as 90 to 300 V and the circuit is burdensome and easy to win. Also, due to its configuration, it is said that it is difficult to display minute dots as small as a CRT on a small PDP.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide an electron flow type electron tube having a minute shape that operates stably for a long period of time.

[0008]

In the electron tube provided with a cathode as an electron emission source and a plate, the electron emission source is caused by impurity atoms (molecules) from the tube wall of the electron tube and others. Is filled with an inert gas for preventing it from being contaminated and deteriorated, and the average free path of electrons for collision with the atom (molecule) of the inert gas is λeg, the impurity atom (molecule) The mean free path is λmg, and the distance between the cathode and the plate is d.
_{When 1} , the distance d is set so that the following equation (1) is satisfied.
It is achieved by a gas filled electron flow type electron tube, wherein ₁ is set. λeg> d ₁ > λg≈λmg Equation (1)

By setting as in the above equation (1), the impurity atoms (molecules) generated from the tube wall of the electron tube or the like and deteriorating the electron emission source as the cathode are the atoms of the enclosed inert gas ( (Molecules) cannot reach the electron emission source, so it does not contaminate the electron emission source, and the electrons emitted from the electron emission source reach the plate without being blocked by other electrons, which stabilizes the electron tube for a long time. Works.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a gas filled electron flow type electron tube according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view of a gas filled electron flow type electron tube 10 according to an embodiment of the present invention. Inside the electron tube 10, for example, tungsten (W), tantalum (Ta)
Alternatively, an electron-emitting device 4 as a cathode having a rhenium (Re) needle 3 is provided, and a plate serving as an anode comprises a transparent electrode 7 and a phosphor 6 formed on the inner surface side thereof. A voltage is applied between the pointed needle 3 and the transparent electrode 7, and electrons e emitted from the pointed needle 3 and accelerated accelerate the phosphor 6 to reach the transparent electrode 7. In addition, an inert gas, such as helium gas, which should be collided into the electron tube 10 so that the impurity atoms (molecules) m desorbed from the tube wall 2 of the electron tube 10 and the phosphor 6 by a small amount cannot reach the needle 3. It is sealed and a cloud of inert gas atoms (molecules) g is applied between the needle 3 and the tube wall 2.

In the operating state of the electron tube 10 described above, electrons e and impurity atoms (molecules) m coexist in the sealed inert gas, but the atoms (molecules) g of the sealed inert gas are present.
The mean free path of the electron e in collision with λeg, the mean free path of the enclosed inert gas atom (molecule) g is λg, the mean free path of the impurity atom (molecule) m is λmg, and the needle 3 and the transparent electrode. 7 and the distance d ₁ between
Establish the relationship. λeg> d ₁ > λg≈λmg Equation (1)

That is, the mean free path λ is an atom (molecule)
Although it is inversely proportional to the cross-sectional area of the electron, the cross-sectional area of the emitted electron e is much smaller than the cross-sectional area of the impurity atom (molecule) m, so the electron e collided with the enclosed inert gas atom (molecule) g. After that, the mean free path λeg, which is the average flight distance until the next collision, is larger (at least 4 times or more) than the similar mean free path λmg for the impurity atom (molecule) m.
The distance d ₁ between the needle 3 and the transparent electrode 7 is larger than the mean free path λmg of the impurity atom (molecule) m and the mean free path λg of the enclosed inert gas atom (molecule) g, and the average of the electrons e. By setting it smaller than the free path, the emitted electrons e reach the transparent electrode 7 from the needle 3 without being blocked by collision.

Further, the voltage applied between the pointed needle 3 as the cathode and the transparent electrode 7 constituting the plate is not more than the dissociation voltage at which the enclosed inert gas does not generate discharge, for example, 24.6 V or less for helium gas. To do. Of course, even with the applied voltage at this level, the electrons e are sufficiently accelerated.

Further, the pressure of the inert gas filled in to prevent the electron-emitting source needle 3 from being contaminated by impurity atoms (molecules) m is the distance d ₂ between the tube wall 2 and the needle 3. Can be derived by setting the following equation (3). d ₂ > 3λmg ··· Equation (3)

That is, in order to prevent the impurity atom (molecule) m desorbed from the tube wall 2 from reaching the needle 3, the needle 3
The distance d ₂ between the tube wall 2 and the tube wall 2 is set to 3 times or more of the mean free path λmg of the impurity atom (molecule) m. As described above, the mean free path λ is inversely proportional to the cross-sectional area of the atom (molecule), but the impurity atom (molecule) m is larger than the cross-sectional area of the helium atom regardless of its type. The path λ _He is the mean free path λ of impurity atoms (molecules)
Greater than mg. Therefore, it suffices to set it as in the following equation (2). d ₂ > 3λ _He ······ Equation (2)

For example, considering an electron tube 10 with d ₂ = 10 μm = 1 × 10 ^-5 m, from equation (3), λ _He <3.3 × 1
Although the 0 ^-6 m, the pressure P _{the He} helium gas corresponding to the mean free path lambda _{the He} is more 45 Torr. Also,
In considering the electron tube 10 of _{d 2 = 0.15mm = 15 × 10} -5 m, λ He <5 × 10 -5 m , and the pressure P _{the He} helium gas corresponding to the mean free path lambda _{the He} is 3Torr more is there. That is, when helium is filled as the inert gas, it is 45 for the electron tube 10 with d ₂ = 10 μm.
Electron tube 10 with pressure over Torr and d ₂ = 0.15 mm
For the above, it is sufficient to seal at a pressure of 3 Torr or more.

That is, the electron tube 1 according to the embodiment of the present invention.
0 is similar to the FED of the conventional example in that it uses electrons e that are field-emitted, but it is also possible to use heat-emitted electrons and that it is gas-filled.
Different from ED. Further, it is similar to the PDP 20 of the conventional example in that it is filled with gas, but the electron tube 10 of the embodiment of the present invention is not plasma-discharged, so the PDP 2
It is completely different from 0.

The gas filled electron flow type electron tube 10 according to the embodiment of the present invention is constructed as described above. Next, its operation will be described.

Referring to FIG. 1, in a gas filled electron flow type electron tube 10 according to an embodiment of the present invention, helium gas is filled in the electron tube 10 at a predetermined pressure derived from the above equation (3). By applying a voltage lower than the dissociation voltage of helium gas of 24.6 V between the needle 3 as a cathode and the transparent electrode 7 forming the plate, the helium gas does not cause discharge and the needle 3 From e
Are field-emitted. Since the distance d ₁ between the needle 3 and the transparent electrode 7 is set to be smaller than the mean free path λeg of the electron e, the electron e passes through the phosphor 6 without being blocked by another collision. It shines and reaches the transparent electrode 7.

Although a small amount of impurity atoms (molecules) m are desorbed from the tube wall 2 of the electron tube 10 in the helium gas, the distance d ₂ between the tube wall 2 and the needle 3 is the impurity atom ( Since the average free path λ _He of helium, which is larger than the average free path λ mg of the molecule) m, is set to be three times or more as large as the average free path λ _He of helium, the impurity atom (molecule) m collides with the helium atom and reaches the needle 3. Therefore, the contamination of the needle 3 does not occur, and the electron tube 10 operates stably for a long time.

That is, the phosphor 6 can be turned on and off by turning on and off the applied voltage. Moreover, by arranging the units in which the red, green, and blue phosphors are shared by the three electron tubes 10 in a plane,
The electron tube 10 of the book can be operated as a small full-color flat display panel having one pixel. (Alternatively, it can be used as a known color filter type display.)

Although the embodiments of the present invention have been described with reference to the drawings, the present invention is not limited to these, and various modifications can be made based on the technical idea of the present invention.

For example, in the embodiment of the present invention, only the transparent conductive film 7 and the fluorescent material 6 forming the plate, the pointed needle 3 as the cathode are installed in the electron tube 10, but FIG. 2 shows a first modification. as the electron tube 10 'shown, T ₁ the temperature of the plate side, T ₁ the temperature of the cathode side as T _2>
By making a temperature difference with T ₂ , the enclosed helium gas convects from the upper side along the tube wall 2 as shown by the arrow, so that the getter 8 for trapping impurity atoms (molecules) m is attached to the tube wall. By setting along 2, the needle 3
Can be covered with helium having a higher purity, and deterioration of the needle 3 as an electron emission source can be prevented.

As a second modification, a grid 9 may be provided inside the electron tube 10 ″ shown in FIG. 3 to control the flow of emitted electrons, and the electron emitting element 4 may be provided with a sharp needle instead of the grid 9. When forming 3, the gate electrodes may be formed on both sides of the same at the same time, and the emission electron flow may be controlled by the voltage applied to the gate electrode.

Further, in the embodiment of the present invention, the electron emitting element 4 having only one pointed needle 3 as the electron emitting source is adopted, but a plurality of pointed needles 3 are included in one electron emitting element 4. May be formed, whereby the flow of the emitted electron flow reaching the transparent electrode 7 is averaged and the current is further stabilized.

Further, in the embodiment of the present invention, the electron e is field-emitted from the apex needle 3 by utilizing the tunnel effect, but the electron-emitting device 4 is made large within the range allowed in principle ( For example, 3 mm square), the tip needle 3 as a cathode is heated by a heater, or the tip needle 3 is externally heated by a laser whose beam diameter is narrowed to a unit of μm. You may allow it. It goes without saying that the field emission and the heat emission may be used together.

Further, in the embodiment of the present invention, the electron tube 10 as an image tube is exemplified, but the gas-filled electron flow type electron tube of the present invention is not only used as an image tube, but also the electron energy at the surface where electrons collide. It is also possible to apply the conversion to other than video. For example, by providing a photoconductor instead of the phosphor 6, it is possible to eliminate the static charge from the photoconductor that has been previously charged with the static charge.

[0029]

As described above, since the gas-filled electron flow type electron tube of the present invention has a minute electron-emitting device having an electron emission source as a cathode and is filled with an inert gas,
The electron tube can be made into a minute shape, and the impurity atoms (molecules) desorbed from the tube wall are shielded by the enclosed gas and do not pollute and deteriorate the electron emission source, so that the electron tube operates stably for a long time.
Therefore, by providing a phosphor on the plate side of the electron tube, a monochrome image tube can be obtained, and by arranging the units in which the red, green, and blue phosphors are shared among the three electron tubes in a plane, a compact and full-color image can be obtained. Flat panel
It can also be a display.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a gas filled electron flow type electron tube according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a gas filled electron flow type electron tube of a first modified example.

FIG. 3 is a schematic cross-sectional view of a gas filled electron flow type electron tube of a second modified example.

FIG. 4 is a schematic sectional view of an electron-emitting device in a conventional FED.

FIG. 5 is a schematic partial sectional view of a conventional plasma display panel.

[Explanation of symbols]

 2 Tube Wall 3 Needle 4 Electron Emitting Element 5 Plate 6 Transparent Conductive Film 7 Phosphor 8 Getter 9 Grid 10 Gas Filled Electron Flow Electron Tube

Claims (7)

[Claims] 1. An electron tube including a cathode as an electron emission source and a plate, for preventing the electron emission source from being contaminated and deteriorated by impurity atoms (molecules) from the tube wall of the electron tube and the like. An inert gas is enclosed, and the average free path of electrons is λeg, the average free path of the inert gas atoms (molecules) is λg, and the impurity atoms are in collision with the atoms (molecules) of the inert gas. When the mean free path of the (molecule) is λmg and the distance between the cathode and the plate is d ₁ , the distance d ₁ is set so that the following expression (1) is established. A gas filled electron flow electron tube. λeg> d ₁ > λg≈λmg Equation (1) 2. When the distance between the cathode and the tube wall is d ₂ and the mean free path of helium gas is λ _He ,
The gas filled electron flow type electron tube according to claim 1, wherein the distance d ₂ is set so that the following expression (2) is established. d ₂ > 3λ _He ······ Equation (2) 3. The cathode is formed in the shape of a single needle or a plurality of needles, a voltage lower than the dissociation voltage of the inert gas is applied between the cathode and the plate, and electrons are field-emitted from the cathode. The gas filled electron flow type electron tube according to claim 1 or 2, which is accelerated toward the plate. 4. A voltage equal to or lower than the dissociation voltage of the inert gas is applied between the cathode and the plate, the cathode is heated by a heater, and thermoelectrons are emitted from the cathode toward the plate. Claim 1 accelerated
Alternatively, the gas filled electron flow type electron tube according to claim 2. 5. A temperature difference is provided between the temperature on the plate side and the temperature on the cathode side to generate convection in the enclosed inert gas, and the impurity atoms (molecules) are included.
The gas filled electron flow type electron tube according to any one of claims 1 to 4, wherein a getter for capturing the gas is provided inside along the tube wall. 6. The gas-filled electron according to claim 1, wherein a gate electrode or a grid for controlling a flow of electrons emitted from the cathode is provided in the vicinity of the cathode. Flow type electron tube. 7. The gas-filled electron according to claim 1, wherein a phosphor that emits light upon collision with the electron is integrally provided on the plate and is used as a picture tube. Flow type electron tube.