JPH11120931A - Electron gun and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron gun capable of limiting the electron emission area of a cathode without increasing the number of part items and to provide its manufacturing method. SOLUTION: This electron gun is constituted of a cathode, a first grid electrode 16G1 and a second grid electrode 16G2 serving as grid electrodes guiding the electrons emitted from the cathode in one direction, and a conductive plate formed with an electron passing hole having the central axis B passing through the center section of the surface of the cathode, passing through the center sections of the surfaces of the first grid electrode 16G1 and the second grid electrode 16G2 , and perpendicular to the surfaces of the first grid electrode 16G1 . and the second grid electrode 16G2 . A low-work function area A1 is provided at the center section of the surface of the cathode, and a high-work function area A2 is provided at the peripheral section of the center section of the surface of the cathode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube (CR)
T), an electron gun for a cathode ray tube used in an electron microscope, an electron beam exposure apparatus, and the like, and a method for producing the same, and particularly to an improvement in a cathode of the electron gun.

[0002]

2. Description of the Related Art FIG. 6 is an enlarged sectional view showing an example of the vicinity of a cathode of a conventional electron gun disclosed in Japanese Patent Application Laid-Open No. 5-198250. In FIG. 6, 1 is a heater, 2
Is a cylindrical sleeve made of molybdenum formed so as to surround the heater 1, 3 is a base metal for applying or spraying an electron-emitting substance for an oxide cathode, and holds a pellet for an impregnated cathode. And 4 are cathode pellets, which are electron-emitting substances, and 12 is a cap.

In a conventional electron gun, a cap 12 having an opening 11 having a predetermined diameter is attached to a cathode pellet 4 of a cup 3.
Is attached to the cathode from the side where the is formed, and the emission of electrons from the cathode pellet 4 is restricted by the opening 11. According to this conventional example, substantially the same effect can be obtained when the oxide cathode is used as the cathode and when the impregnated cathode described later is used.

FIG. 7 is an enlarged sectional explanatory view showing another example near the cathode of a conventional electron gun disclosed in Japanese Patent Application Laid-Open No. 7-85807. In FIG. 7, 1 is a heater, 2
Is a sleeve formed by laminating a cylindrical inner sleeve 2a and an outer sleeve 2b made of molybdenum formed so as to surround the heater 1; 4, a cathode pellet; 9, an eyelet;
6 _G1 indicates the first grid electrode, and 16 _G2 indicates the second grid electrode. The sleeve 2 is fixed by a ribbon 10 such that it can be hung down from a cylindrical eyelet 9 made of metal. The upper portion of the inner sleeve 2a is closed, and the outer sleeve 2b has an opening 11 at the upper portion.

[0005] The electron emission possible region is constituted by an exposed portion of the surface of the cathode pellet 4 fixed and mounted on the upper central surface of the closed portion of the inner sleeve 2a. The cathode used in this conventional example is generally called an impregnated cathode. The cathode pellet 4 is obtained by impregnating a porous tungsten base with an emitter agent in which BaO, CaO, and Al ₂ O ₃ are mixed at a ratio of 4: 1: 1 (molar ratio). Further, in order to lower the work function of the surface, lower the operating temperature and improve the reliability, the electron emission surface is coated with Ir or Os for several 100 nm and used. The sleeve 2 and the ribbon 1
The cathode is formed by the 0, the eyelet 9, and the cathode pellet 4.

[0006] A first grid electrode 16 _G1 which is a metal electrode plate is provided above the cathode and separated from the cathode. The first grid electrode 16 _G1 is formed with a first grid electron passing apertures 26 _G1.

Further, a second grid electrode 16 _G2 which is a metal electrode plate is disposed above the first grid electrode 16 _G1 . The second grid electrode _16G2 has a second grid electron passage hole _26G2 . Although not shown, a plurality of grid electrodes are further arranged above the second grid electrode. The broken line indicated by "B" in the figure indicates the central axis of each grid electron passage hole.

FIG. 8 is a cross-sectional explanatory view showing a conventional electron gun being assembled, and is an explanatory view showing a step of aligning an outer sleeve, a first grid electrode, and a second grid electrode. 8, the same parts as those in FIG. 7 are indicated by the same reference numerals. Further, 14 is an alignment rod, 16 _G3 is a third grid electrode, 16 _G4 is a fourth grid electrode, 16 _G5 is a fifth grid electrode, 26 _G3 is a third grid electron passage hole,
26 _G4 indicates a fourth grid electron passage hole, and 26 _G5 indicates a fifth grid electron passage hole. Aligning rod 14 with outer sleeve 2
b, first grid electrode 16 _G1 , second grid electrode 1
6 _G2 , third grid electrode 16 _G3 , fourth grid electrode 16
In the inserted state to each opening or passage holes _G4 and fifth grid electrode 16 _G5, the outer sleeve 2b by the bead glass (not shown), the first grid electrode 16 _G1, second grid electrode 16 _G2, third grid electrode 16 _G3 Then, the fourth grid electrode 16 _G4 and the fifth grid electrode 16 _G5 are fixed.

In this way, it can be adjusted so that the central axis B of the electron passage hole of the first grid electrode and the electron passage hole of the second grid electrode pass through the center of the opening of the outer sleeve.

FIG. 9 is an explanatory sectional view showing a conventional electron gun being assembled, and is an explanatory view showing a step of inserting an inner sleeve into an outer sleeve. 9, the same parts as those in FIGS. 7 and 8 are denoted by the same reference numerals. In this step, after removing the alignment rod 14, the outer sleeve 2 is removed.
b, the inner sleeve 2a is inserted from the direction shown by the arrow C and fixed.

FIG. 10 is a cross-sectional view of the vicinity of the cathode showing the electron trajectory of electrons emitted from the cathode in a conventional electron gun using a cathode which does not limit a normal electron emission region. 10, the same parts as those in FIG. 9 are indicated by the same reference numerals. Further, reference numeral 15 denotes an electron orbit of electrons emitted from the cathode. FIG. 10 shows only the cathode pellet 4, the electron trajectory 15, the first grid electrode _16G1 , the second grid electrode _16G2 , and the third grid electrode _{16G3 in} order to clearly show the electron trajectory 15. . As can be seen from the figure, the electron trajectory of an electron radiated from near the central axis has a crossing point with another electron trajectory far from the cathode, but the electron trajectory of an electron radiated from a position distant from the central axis B is , And has an intersection with another electron orbit at a position close to the cathode. The fact that the intersection of the electrons emitted from a position away from the central axis does not coincide with the intersection of the electrons emitted from the vicinity of the central axis contributes to a halo when the electron beam is incident on the phosphor screen.

[0012] For this reason, it is preferable that the diameter of the electron-emitting region be small, since the electron is not emitted from a place far away from the central axis. Further, when the diameter of the electron-emitting area is reduced, the current density increases when the same current is extracted when the diameter is large. Therefore, electrons emitted from a location away from the central axis are strongly repulsed outward from the central axis, so that the intersection of the electron orbits moves to the phosphor screen side and more electron orbits intersect at the same intersection. become. For these reasons, if the diameter of the electron-emission-possible region is limited to a small value, the generation of halos can be reduced, so that the effect of improving the focusing characteristics can be obtained. However, in order to obtain this effect sufficiently, the diameter of the electron emission region must be formed to be considerably smaller, for example, about one fourth of the diameter of the first grid electrode. Furthermore, it is necessary that the center point of the electron emission possible region is located on the center point of the first grid electrode, the second grid electrode, or the like. As described above, the electron gun according to the conventional example has an electron emission area of, for example, 0.1 mm
Since it is formed with a small area and the center point of the electron dischargeable region is located on the center point of the first grid electrode, the second grid electrode, or the like, the focusing characteristics can be improved.

[0013]

As a method for manufacturing a cathode having a limited electron emission area, a method as in the case of Conventional Example 1 shown in FIG. 6 can be considered. But,
Not only does the number of parts increase, which leads to an increase in cost, but also it is difficult to accurately align the center point of the limited electron emission surface of the cathode with the center axis of the electron passage hole of the grid electrode.

The conventional example 2 shown in FIG. 7 which solves the problem of aligning the center axes of the electron passing holes is also difficult to manufacture for the following reasons, for example. First, after removing the alignment rod, the cathode pellet fixed to the inner sleeve must be inserted into the opening of the outer sleeve, and the outer sleeve and the inner sleeve must be fixed by welding or the like. This operation must be performed while looking through the grid electrode side. At this time, the cathode pellet and the opening of the outer sleeve are very small, and there is a certain distance from the grid electrode to the sleeve. Is required. Further, as is apparent from FIG. 7, two sleeves are required in this case. Therefore, particularly in the case of the impregnated cathode, it is necessary to use expensive processed parts made of Ta, Mo, or the like, which undesirably increases the cost. Furthermore, the increase in the number of parts increases the total heat capacity, and causes many problems, such as an increase in power required for driving and a long time from the passage of current to the heater to the emission of electrons.

[0015] The first problem is that there is a problem in manufacturing due to the positioning of the electron-emitting area of the cathode in the presence of a plurality of grid electrodes. In other words, there is a certain distance from the cathode to the grid electrode, and when the number of components is large, the handling becomes poor, and it becomes an obstacle when the electron emission area of the cathode is axially aligned. A second problem is that many adverse effects such as an increase in cost and an increase in power due to an increase in the number of components are raised.

An object of the present invention is to provide an electron gun including a cathode having a limited electron emission area without increasing the number of parts, and to provide a method of manufacturing the same.

[0017]

According to a first aspect of the present invention, there is provided an electron gun comprising a cathode, and a grid electrode for guiding electrons emitted from the cathode in one direction, and passing through a central portion of the cathode surface. A conductive plate in which an axis perpendicular to the cathode surface passes through the center of the grid electrode surface and is perpendicular to the grid electrode surface, and the grid electrode has an electron passage hole having the axis as the central axis. Wherein the low work function region is provided in the center of the cathode surface, and the high work function region is provided in the periphery of the center of the cathode surface.

In the electron gun according to claim 2 of the present invention, the work function in the low work function region is 1.9 eV or less, and the work function in the high work function region is 2.1 eV or more.

According to a third aspect of the present invention, in the electron gun, the work function of the low work function region is 0.5 to 1.9 eV,
The work function of the high work function region is 2.1 to 6.0 eV.

In the electron gun according to a fourth aspect of the present invention, a difference between a work function in the low work function region and a work function in the high work function region is 0.2 eV or more.

In the electron gun according to a fifth aspect of the present invention, a difference between a work function in the low work function region and a work function in the high work function region is 0.2 to 5.5 eV.

The electron gun according to claim 6 of the present invention has the following features.
Ir, Os, Ru and R are formed on the surface of the low work function region.
e, a thin film made of at least one metal of e is provided.

The electron gun according to claim 7 of the present invention comprises:
Ir, Os, Ru and R are formed on the surface of the low work function region.
e, a thin film made of an alloy of at least two metals is provided.

Further, the electron gun according to claim 8 of the present invention comprises:
A thin film made of at least one metal of Si, Pt, Ta, Mo and Zr is provided on the surface of the high work function region.

Further, the electron gun according to the ninth aspect of the present invention comprises:
A thin film made of an oxide of at least one metal of Si, Pt, Ta, Mo and Zr is provided on the surface of the high work function region.

In the electron gun according to claim 10 of the present invention, Si, Pt, Ta, M
A thin film made of an alloy of at least two metals of o and Zr is provided.

According to the eleventh aspect of the present invention, there is provided the electron gun, wherein Si, Pt, Ta, M
A thin film made of an oxide of an alloy of at least two metals of o and Zr is provided.

According to a twelfth aspect of the present invention, there is provided a method for manufacturing an electron gun, wherein a grid electrode for guiding electrons emitted from the cathode in one direction is arranged at a predetermined interval above the cathode. The electron gun according to claim 1, wherein a grid electrode is disposed above the cathode, and a film forming jig is inserted into the electron passage hole so that a center axis of the electron passage hole is the same as that of the electron gun. A thin film is provided on the surface of the low work function region by using one of the sputtering method and the vapor deposition method while adjusting so as to pass through the center point of the low work function region.

A method of manufacturing an electron gun according to a thirteenth aspect of the present invention is a method of manufacturing an electron gun, wherein a grid electrode for guiding electrons emitted from the cathode in one direction is arranged at a predetermined interval above the cathode. The electron gun according to claim 1, wherein a grid electrode is arranged on the cathode, and the high work function region is formed in a state where a mask is provided on a portion of the cathode where electrons are emitted. Then, the low work function region is formed with the mask removed.

[0030]

Next, an embodiment of the electron gun of the present invention and a method of manufacturing the same will be described.

Embodiment 1 Embodiment 1 of an electron gun and a method for manufacturing the same according to the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view showing Embodiment 1 of the electron gun of the present invention. 1, the same parts as those in FIG. 6 are denoted by the same reference numerals. Further, 16 _G1 denotes a first grid electrode, 16 _G2 denotes a second grid electrode, 26 _G1 denotes a first grid electron passage hole, and 26 _G2 denotes a second grid electron passage hole. FIG. 1A is an explanatory sectional view showing Embodiment 1 of the electron gun of the present invention, and FIG. 1B is a top view of the electron gun of FIG. 1A viewed from the second grid electrode side. FIG.

In FIG. 1, the cathode pellet 4 is an impregnated cathode. The surface of the cathode pellet 4 is coated with a 200 nm thick Ir (iridium) thin film 5 in an area smaller than the first grid electron passage hole.
A portion Ir thin film 5 is coated out of cathode pellet 4 surface called a low work function area A _1, the central axis B is low work function area A of the electron passing holes of all of the grid electrode comprising a first grid electrode 16 _{G1 1} is formed so as to pass through the center point.

As the thin film, other than the Ir thin film, Os
A thin film made of (osmium), Ru (ruthenium) or Re (rhenium), or a thin film having a multilayer structure made of at least two of Ir, Os, Ru and Re may be used. Further, a thin film made of an alloy of at least two metals of Ir, Os, Ru and Re may be used. For example, substantially the same effect can be obtained by using Os, an Os-Ru alloy, or Re. Note that an appropriate method for forming a film may be selected depending on the material of the thin film. For example, a sputtering method or an evaporation method is used.

The work function of the low work function region formed as described above is 1.9 eV or less, preferably 0.5 to 1.9.
eV. The reason for setting the low work function region to 1.9 eV or less is that if it is 1.9 eV or less, sufficient emission as an electron gun can be obtained at about 1000 ° C. to 1050 ° C. which is the operating temperature of a normal impregnated cathode. This is because it can be done.

Further, the work function of the high work function regions _{A 2} which is not a coating of cathode pellet 4 surface 2.1eV or more, preferably a 2.1～6.0EV. The reason for setting the work function of the high work function region to 2.1 eV or more is that at the operating temperature of the above-described ordinary impregnated cathode, electron emission is slight, and unnecessary electrons are emitted from portions other than the center of the cathode. It is to prevent that.
Thus, the cathode in order to function effectively in the electron gun, the difference between the low work function regions _{A 1} and the high work function regions _{A 2} is more than 0.2 eV, preferably a difference of 0.2~5.5eV is necessary.

Next, a description will be given of a position adjustment in assembling an electron gun as Embodiment 1 of the method for manufacturing an electron gun of the present invention with reference to the drawings. FIG. 2 is an explanatory sectional view showing the vicinity of the cathode of the electron gun of FIG. 1 during assembly. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals. Further, reference numeral 8 denotes a hermetic component, and 7a denotes a film forming jig.

[0038] First, assembled hermetically part 8 which is fixed to the cathode and previously welded to the first grid electrode 16 _G1 (welded portion is not shown). Next, a film forming (ie, coating) jig (hereinafter, referred to as a “film forming jig”) 7a is inserted from the first grid electrode _16G1 side. Subsequently, the cathode is inserted into the hermetic component. At this time, it is necessary to accurately define the distance between the cathode and the first grid electrode _16G1 . This is because a voltage that does not emit electrons when provided in an electron gun, that is, a cutoff voltage is determined by the distance between the cathode and the first grid electrode and the second grid electrode. For this reason, the film-forming jig 7a is set to an exact length in advance, and when the cathode surface contacts the film-forming jig 7a,
The cathode is fixed to the hermetic component 8 by laser welding or the like. At the center of the film forming jig 7a,
A through hole 27 is provided so that only a desired portion of the cathode surface is exposed. In this state, the integrated component shown in FIG.
It was coated at 20 μm to a thickness of 200 nm. Although not shown in the drawing, at this time, a film was formed with a predetermined jig so as to prevent Ir from adhering to the first grid electrode and the like.

Lastly, by utilizing a separate axial alignment notch provided beforehand in any part of the part where the first grid electrode and the cathode are integrated, and the electrodes after the second grid electrode. An electron gun is obtained by assembling the second and subsequent grid electrodes and fixing each part with bead glass.

In order to evaluate the emission characteristics of the cathode alone, especially how the electron emission distribution is performed, only the cathode is taken out of the hermetic part of the electron gun shown in FIG. Was done. In this measurement, while the cathode was moved on the X and Y stages in 10 μm steps, electrons that passed through the holes of the Mo plate with a diameter of 10 μm facing the cathode were captured by a Faraday cup, so that the electron emission on the cathode surface was reduced. The measurement was performed using an apparatus capable of evaluating how the particles are distributed. FIG. 3 is a graph showing the electron emission distribution of the cathode of the electron gun of FIG. In FIG. 3, the vertical axis indicates the emission current (μA), and the horizontal axis indicates the position where the measurement was performed, as a distance (μm) from an arbitrary point on the X and Y stages. This is from a low work function regions A ₁ coated with Ir thin as about as compared to the high work function regions A ₂ uncoated 4
Double electron emission is obtained. However, as can be seen from FIG. 3, it can be seen that some electron emission is also performed from the high work function region.

As described above, according to the method of manufacturing an electron gun of the present invention, it is possible to easily assemble an electron gun including a cathode having a limited electron emission area without increasing the number of parts. In such an electron gun which is E and in, because the diameter of the low work function regions consist A ₁ electron emitting region is limited smaller, there is no possible central axis electron emission from a place far away from the B is performed So the central axis B
It is possible to reduce the occurrence of a so-called halo caused by the emission of electrons from the location far away from the device, and to improve the focusing characteristics.

Embodiment 2 According to the above-described first embodiment of the electron gun and the method for manufacturing the same according to the present invention, Ba is relatively actively vaporized from a region that does not emit electrons, and thus has no effect on grid emission. An example in which this point is improved will be described in the present embodiment.

Embodiment 2 of an electron gun and a method of manufacturing the same according to the present invention will be described with reference to the drawings. FIG. 4 is an explanatory view showing Embodiment 2 of the electron gun of the present invention during assembly.
FIG. 4A is an explanatory cross-sectional view of the electron gun, and FIG.
FIG. 4 is an explanatory view showing the film forming jig of FIG. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals. Reference numeral 7b denotes a film forming jig as a mask at the time of coating.

The film forming jig 7b can cover a low work function region on the surface of the cathode pellet 4. Deposition jig 7b has a hole 37a that can expose a portion located lower _G1 least first grid electron passing apertures 26 of the high work function regions. The film forming jig 7b
The portion 37b covering the low work function region is a columnar member provided along the central axis of the hole 37a. further,
The portion 37b covering the low work function region is fixed to the center of the hole using a portion 37b covering the low work function region and a thin plate-like member 37c provided between the wall surfaces of the hole 37a. The side surface of the thin plate member is flush with the end surface of the hole. Therefore, the thin plate-like member 37c is
Part of the hole 37a is closed by the thickness of the member. However, if the thickness of the thin plate-like member 37c is sufficiently small, no problem occurs because the film is formed below the thin plate-like member 37c.

First, as in the first embodiment, the hermetic component 8 fixed to the cathode and the first grid electrode 1
6 _G1 is assembled by welding in advance (the welded portion is not shown). Next, the film-forming jig 7b is inserted from the first grid electrode _16G1 side, and the distance between the first grid electrode and the cathode is defined in the same manner as the above over the entire length of the film-forming jig 7b. Hermetic parts 8 by laser welding, etc.
Fix the cathode to. In this state, the integral component shown in FIG. 4 is set in the sputtering or vapor deposition apparatus, and the electron emitting portion having a diameter of 120 μm covered by the film forming jig 7b on the impregnated cathode surface is not coated. SiO ₂ (silicon oxide) thin film 6 in work function region
Was coated to a thickness of 100 nm.

As the thin film, other than SiO ₂ thin film, S
i (silicon), Pt (platinum), Ta (tantalum), M
A thin film made of o (molybdenum) or Zr (zirconium), or a thin film having a multilayer structure made of at least two of Si, Pt, Ta, Mo, and Zr may be used. Further, a thin film made of an oxide of Pt, an oxide of Ta, an oxide of Mo, or an oxide of Zr, or S
A thin film having a multilayer structure composed of at least two of the oxide of i, the oxide of Pt, the oxide of Ta, the oxide of Mo, and the oxide of Zr may be used. Also, Si, Pt, T
A thin film made of an alloy of at least two metals of a, Mo, and Zr, or a thin film made of an oxide of an alloy of at least two metals of Si, Pt, Ta, Mo, and Zr may be used. Note that an appropriate method for forming a film may be selected depending on the material of the thin film. For example, a sputtering method or an evaporation method is used.

Subsequently, as shown in FIG. 5, an Ir thin film 5 was coated on the entire surface with a thickness of 200 nm with the mask removed. FIG. 5 is an explanatory sectional view showing Embodiment 2 of the electron gun of the present invention during assembly. 5, the same parts as those in FIGS. 1 and 4 are denoted by the same reference numerals. Although not shown in the figure, the first grid electrode is covered with a jig so that the film-forming substance is not sputtered on the surface of the first grid electrode in forming any of the SiO ₂ thin film and the Ir thin film. Was.

The emission characteristics of the thus assembled cathode alone were evaluated in the same manner as in the first embodiment. As a result, almost no electrons were emitted from the high work function region, and no emission was observed from the low work function region. Emission characteristics similar to those of the first embodiment were obtained.

According to the manufacturing method shown in the second embodiment, it is possible to easily assemble an electron gun including a cathode having a limited electron emission area without increasing the number of parts. In the electron gun obtained in this manner, the diameter of the electron-emitting region composed of the low work function region is limited to a small value, and no electron is emitted from the peripheral portion. Therefore, since electrons are not emitted from a location far from the central axis B, so-called halo generation caused by electron emission from a location far from the central axis B can be reduced, and the focusing characteristics can be greatly improved. Can be improved. In addition, Ba from a portion that does not emit electrons
Unnecessary evaporation is almost completely suppressed, which is very effective for grid emission.

In this embodiment, FIG. 4 and FIG. 5, the S
After the iO ₂ thin film 6 is provided, the Ir thin film 5 is provided on the exposed portion of the surface of the cathode pellet 4 and on the surface of the SiO ₂ thin film 6. However, after the Ir thin film is provided on the entire surface of the cathode pellet, the SiO ₂ thin film may be provided only above the high work function region of the cathode pellet.

Further, in the present embodiment, the electron-emitting area is a circle, but it is not necessary that the area is an accurate circle.
An oval shape, a rectangular shape, or the like may be used to improve focusing characteristics in a target direction such as a horizontal direction or a vertical direction. Further, it may be inclined in a direction that is neither horizontal nor vertical. The shape of the electron-emitting area may be appropriately selected according to the specifications of the electron gun or a device such as a CRT in which the electron gun is used.

Although there is no particular limitation on how the electron emission region is limited, it must be determined in consideration of the convergence of the electron beam, the load on the drive circuit, and the like.

[0053]

According to the first aspect of the present invention, there is provided an electron gun comprising a cathode, and a grid electrode for guiding electrons emitted from the cathode in one direction. An electron gun having an axis perpendicular to the grid electrode surface and having an axis perpendicular to the grid electrode surface, wherein the grid electrode is formed of a conductive plate having an electron passage hole formed around the axis. The low work function region is provided in the center of the cathode surface, and the high work function region is provided in the periphery of the center of the cathode surface. The area can be limited.

In the electron gun according to claim 2 of the present invention, the work function in the low work function region is 1.9 eV or less and the work function in the high work function region is 2.1 eV or more. The electron gun can be used at the operating temperature, and electrons can be prevented from being emitted from other than the center of the cathode.

According to a third aspect of the present invention, in the electron gun, the work function of the low work function region is 0.5 to 1.9 eV,
Since the work function of the high work function region is 2.1 to 6.0 eV, the electron gun can be used at a normal operating temperature and electrons are not emitted from a point other than the center of the cathode. be able to.

In the electron gun according to the fourth aspect of the present invention, since the difference between the work function in the low work function region and the work function in the high work function region is 0.2 eV or more, the cathode can be effectively used in the electron gun. Can function.

In the electron gun according to the fifth aspect of the present invention, the difference between the work function in the low work function region and the work function in the high work function region is 0.2 to 5.5 eV. It can function effectively in a gun.

The electron gun according to claim 6 of the present invention is
Ir, Os, Ru and R are formed on the surface of the low work function region.
Since a thin film made of at least one metal of e is provided, a low work function region can be easily formed.

The electron gun according to claim 7 of the present invention has the following features.
Ir, Os, Ru and R are formed on the surface of the low work function region.
Since a thin film made of an alloy of at least two metals of e is provided, a low work function region can be easily formed.

The electron gun according to claim 8 of the present invention has the following features.
Since a thin film made of at least one metal of Si, Pt, Ta, Mo and Zr is provided on the surface of the high work function region, Ba is evaporated from a portion of the cathode pellet that does not emit electrons. Can be suppressed.

The electron gun according to claim 9 of the present invention is
Since a thin film made of an oxide of at least one of Si, Pt, Ta, Mo and Zr is provided on the surface of the high work function region, Ba evaporates from a portion of the cathode pellet that does not emit electrons. Can be suppressed.

In the electron gun according to claim 10 of the present invention, Si, Pt, Ta, M
Since a thin film made of an alloy of at least two metals of o and Zr is provided, Ba can be suppressed from evaporating from a portion of the cathode pellet that does not emit electrons.

Further, in the electron gun according to claim 11 of the present invention, the surface of the high work function region is provided with Si, Pt, Ta, M
Since a thin film made of an oxide of an alloy of at least two metals of o and Zr is provided, Ba can be suppressed from evaporating from a portion of the cathode pellet that does not emit electrons.

A method of manufacturing an electron gun according to a twelfth aspect of the present invention is a method of manufacturing an electron gun in which a grid electrode for guiding electrons emitted from the cathode in one direction is arranged at a predetermined interval above the cathode. The electron gun according to claim 1, wherein a grid electrode is disposed above the cathode, and a film forming jig is inserted into the electron passage hole so that a center axis of the electron passage hole is the same as that of the electron gun. In the state adjusted so as to pass through the center point of the low work function region, a thin film is provided on the surface of the low work function region by using one of the sputtering method and the vapor deposition method. It is possible to reduce the occurrence of halos caused by the emission of electrons from other than the center.

A method of manufacturing an electron gun according to a thirteenth aspect of the present invention is a method of manufacturing an electron gun in which a grid electrode for guiding electrons emitted from the cathode in one direction is arranged at a predetermined interval above the cathode. The electron gun according to claim 1, wherein a grid electrode is arranged on the cathode, and the high work function region is formed in a state where a mask is provided on a portion of the cathode where electrons are emitted. In addition, since the low work function region is formed with the mask removed, Ba can be suppressed from evaporating from a portion of the cathode pellet that does not emit electrons.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing Embodiment 1 of an electron gun of the present invention.

FIG. 2 is an explanatory sectional view showing the vicinity of a cathode of the electron gun of FIG. 1 during assembly.

FIG. 3 is a graph showing an electron emission distribution of a cathode of the electron gun of FIG.

FIG. 4 is an explanatory view showing Embodiment 2 of the electron gun of the present invention during assembly.

FIG. 5 is an explanatory sectional view showing Embodiment 2 of the electron gun of the present invention during assembly.

FIG. 6 is an enlarged sectional view illustrating an example of the vicinity of a cathode of a conventional electron gun.

FIG. 7 is an enlarged sectional explanatory view showing another example near the cathode of a conventional electron gun.

FIG. 8 is an explanatory sectional view showing a conventional electron gun being assembled.

FIG. 9 is an explanatory sectional view showing a conventional electron gun being assembled.

FIG. 10 is an explanatory cross-sectional view near the cathode, showing an electron trajectory of electrons emitted from the cathode in the conventional electron gun.

[Explanation of symbols]

1 heater, 2 sleeves, 3 cups, 4 cathode pellets, 5 Ir thin film, 6 SiO ₂ thin film, 7a,
7b Film forming jig, 8 hermetic parts, 9 eyelets, 10, ribbon, 14 axes alignment rod.

Claims (13)

[Claims] 1. A cathode and a grid electrode for guiding electrons emitted from the cathode in one direction, wherein an axis passing through a center portion of the cathode surface and perpendicular to the cathode surface is a center of the grid electrode surface. An electron gun formed of a conductive plate passing through a portion and being perpendicular to the grid electrode surface, wherein the grid electrode is formed with an electron passage hole having the axis as a central axis, and a low electrode is provided at the center of the cathode surface. An electron gun having a work function region and a high work function region around a central portion of the cathode surface. 2. The work function of the low work function region is 1.9.
eV or less, and the work function of the high work function region is 2.
The electron gun according to claim 1, wherein the electron gun is 1 eV or more. 3. The work function of the low work function region is 0.5
3. The electron gun according to claim 2, wherein the work function of the high work function region is 2.1 to 6.0 eV. 4. The electron gun according to claim 1, wherein a difference between a work function in the low work function region and a work function in the high work function region is 0.2 eV or more. 5. The electron gun according to claim 4, wherein a difference between a work function in the low work function region and a work function in the high work function region is 0.2 to 5.5 eV. 6. The surface of the low work function region, wherein Ir, O
2. The electron gun according to claim 1, wherein a thin film made of at least one of s, Ru and Re is provided. 7. The surface of the low work function region, wherein Ir, O
2. The electron gun according to claim 1, wherein a thin film made of an alloy of at least two of s, Ru and Re is provided. 8. The method according to claim 1, wherein the surface of the high work function region includes Si, P
The electron gun according to claim 1, wherein a thin film made of at least one metal of t, Ta, Mo, and Zr is provided. 9. Si, P
The electron gun according to claim 1, wherein a thin film made of an oxide of at least one of t, Ta, Mo, and Zr is provided. 10. A high work function region surface comprising Si, P
The electron gun according to claim 1, wherein a thin film made of an alloy of at least two metals of t, Ta, Mo, and Zr is provided. 11. The method according to claim 1, wherein the surface of the high work function region has Si, P
2. The electron gun according to claim 1, wherein a thin film made of an oxide of an alloy of at least two metals of t, Ta, Mo and Zr is provided. 12. An electron gun according to claim 1, wherein a grid electrode for guiding electrons emitted from the cathode in one direction is arranged above the cathode while maintaining a predetermined interval. After a grid electrode is arranged above the cathode, a film forming jig is inserted into the electron passage hole, and the center axis of the electron passage hole passes through the center point of a location where the low work function region is formed. A method for producing an electron gun in which a thin film is formed on a surface where a low work function region is formed by using one of a sputtering method and a vapor deposition method in such a state. 13. An electron gun according to claim 1, wherein a grid electrode for guiding electrons emitted from said cathode in one direction is arranged above said cathode while maintaining a predetermined interval. After arranging a grid electrode on the cathode, the high work function region is formed in a state where a mask is provided in a portion of the cathode from which electrons are emitted, and the mask is removed in a state where the mask is removed. A method of manufacturing an electron gun that forms a low work function region.