JPH05182595A - Electron gun - Google Patents

Abstract

PURPOSE:To miniaturize and simplify the structure of an electron gun and eliminate the necessity of adjusting the arrangement and position of a shadow grid relative to a cathode and increase reliability of operation of the electron gun and the ease with which the electron gun is assembled. CONSTITUTION:A shadow grid 19 is simultaneously positioned relative to and fitted along the outer peripheral structure 17 of a cathode 15 and the peripheral portion of the shadow grid 19 is welded onto the flat surface 17a of the outer peripheral structure 17 through a welding hole 20, whereby the shadow grid 19 and the structure 17 are coupled and held in a predetermined positional relation to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun used for an electron tube such as a traveling wave tube.

[0002]

2. Description of the Related Art FIG. 10 shows, for example, JP-A-61-20064.
FIG. 4 is a perspective view showing the conventional electron gun shown in Japanese Patent Publication No. 3 in a partially broken view, in which 1 is a heater,
Are embedded in the filler 2. 3 is a cathode having an electron emission surface, which is impregnated with a base containing barium. Four
Is a sleeve that supports the cathode 3, 5 is a control grid, 6 is a control grid support that supports the control grid 5, 7 is a shadow grid, and 8 is a shadow grid support that supports the shadow grid 7.

Next, the operation will be described. First, when the cathode 3 heated by the heater 1 reaches the temperature required for thermionic emission, its electron emission surface has the ability to emit electrons. The control of the amount of emitted electrons is performed by applying a positive or negative potential to the control grid 5 and the cathode 3. At this time, the shadow grid 7 interposed between the control grid 5 and the cathode 3 prevents the electrons emitted from the cathode 3 from directly flowing into the control grid 5.

The control grid 5, the shadow grid 7 and the cathode 3 are arranged with a small space therebetween. Furthermore, the control grid 5 and the shadow grid 7 are aligned along the electron beam emission trajectory from the electron emission surface of the cathode 3.

Also, the support and fixation of the shadow grid 7 is
Similar to the method of supporting the control grid 5, the shadow grid support 8 arranged separately is brazed or welded, or as shown in FIG.
A flat surface 9 is provided on a part of the electron emission surface, and a step 11 is provided on the outer peripheral side surface of the cathode 10.
Crimp the cylindrical portion of the shadow grid 7 onto the cathode 10
And the shadow grid 12 are brought into close contact with each other and then supported and fixed by welding or the like.

On the other hand, the shadow grid 12 is shown as an example. As shown in FIGS. 12 and 13, each of the grids 7 and 12 is made of a thin plate of several tens to several hundreds of μm, and a part thereof is formed into a spherical shape. In addition, it has a lattice structure composed of a large number of radial holes 14 divided by grid spokes 13 having a minute width.

Further, since the shadow grids 7 and the shadow grids 12 are arranged in positions close to the cathodes 3 and 10 having a high temperature, molybdenum or rhenium alloy, which is generally a high melting point material and has good workability, is used. It is being appreciated.

[0008]

Since the conventional electron gun is constructed as described above, for example, the shadow grid 7
In order to support and fix the shadow grid 7, the geometrical arrangement of the shadow grid 7 and the cathode 3 must be adjusted, and the geometrical arrangement of the shadow grid support 8 and the cathode 3 must be adjusted. Not only the number of man-hours for assembling the gun is increased, but also the assembling accuracy is deteriorated.

Further, a space for disposing and fixing the shadow grid support 8 must be separately secured, which causes a problem that the structure of the electron gun is enlarged.

Further, the shadow grid 1 shown in FIG.
In the mounting structure of No. 2, the flat surface 9 is present, and the grid spokes 13 are misaligned or deformed by caulking and fixing with the step 11 at a position different from the flat surface 9 by 90 ° and at a distance. There was a problem that could lead to.

Furthermore, since the shadow grids 7 and 12 are adjacent to the high temperature cathodes 3 and 10, the shadow grids 7 and 12 also become high temperature, and the shadow grids 7 and 12 are high.
There is a possibility that the dimensional deviation between the cathodes 3, 10 and the shadow grids 7, 12 and the deformation of the shadow grids 7, 12 may be caused due to the difference in thermal expansion coefficient between the cathodes 3, 10.

Furthermore, since the flat surfaces of the cathodes 3 and 10 are also impregnated with the impregnating agent, unnecessary impregnating agent is vaporized, which causes a defect of the electron gun, and the shadow grids 7 and 12 are capped. You have to buzz
There is a problem that only the materials having a relatively large Ericsen value can be used as the shadow grids 7 and 12.

The invention of claim 1 is made to solve the above-mentioned problems. The shadow grid support is omitted to simplify the structure and reduce the size of the shadow grid. It is an object of the present invention to obtain an electron gun that can be operated reliably and can be easily assembled by omitting the work of adjusting the position and position.

It is another object of the present invention to provide an electron gun capable of accurately positioning and fixing the shadow grid on the flat surface of the outer peripheral structure.

Further, according to the invention of claim 3, the shadow grid and the outer peripheral side structure can be easily welded,
Moreover, it is an object of the present invention to obtain an electron gun capable of preventing dimensional deviation due to thermal deformation.

Furthermore, according to the invention of claim 4, the shadow grid of molybdenum alloy and the outer peripheral structure of tungsten can be easily welded, and the dimensional deviation due to the difference in thermal expansion coefficient can be prevented. Aim to get an electron gun.

Still another object of the present invention is to obtain an electron gun capable of suppressing the thermal influence of the cathode on the shadow grid.

A further object of the invention of claim 6 is to obtain an electron gun in which the shadow grid can be mounted directly and easily on the cathode in a simple and reliable manner.

[0019]

An electron gun according to the invention of claim 1 is provided on a cathode base constituting a cathode and around the cathode base, and is brazed on the electron emitting surface side of the cathode base. The outer peripheral structure and a bent piece formed in the peripheral portion of the shadow grid and having the inner periphery joined to the outer peripheral surface of the outer peripheral structure on the electron emission surface side in a positionable manner are provided. A flat surface is formed on the electron emission surface side of the outer peripheral side structure to form a plurality of welding holes in the peripheral portion of the shadow grid so that the peripheral portion and the flat surface can be supported. It is designed so that welding can be performed.

In the electron gun according to the invention of claim 2, a flat surface is formed on the electron emission surface side of the outer peripheral side structure so as to position and support the peripheral portion of the shadow grid, and the flat surface is formed on the flat surface. A spot facing portion is formed, and welding with the flat surface can be performed in a state where the peripheral portion of the shadow grid is fitted to the spot facing portion.

Further, in the electron gun according to the third aspect of the present invention, the shadow grid and the outer peripheral structure for supporting the shadow grid on the flat surface are made of molybdenum alloy.

Furthermore, the electron gun according to the invention of claim 4 is a ruthenium which welds a shadow grid made of a molybdenum alloy and a tungsten outer peripheral structure supporting the shadow grid with a flat surface to each other. -A brazing material of molybdenum or platinum is interposed.

Further, in the electron gun according to the invention of claim 5, there is provided between the cathode base and the outer peripheral side structure,
A heat insulating layer is provided on the part excluding the brazed part.

An electron gun according to a sixth aspect of the present invention includes a bending piece which is formed in the peripheral portion of the shadow grid and has an inner periphery joined to the outer periphery of the cathode on the electron emission surface side so as to be positioned. A flat surface formed on the electron emission surface side of the cathode is provided to position and support the peripheral portion of the shadow grid, and a plurality of the peripheral portion and the flat surface are welded to the peripheral portion of the shadow grid. And a flat surface of the cathode and a peripheral portion of the shadow grid are welded with a brazing material.

[0025]

The structure on the outer peripheral side in the invention of claim 1 is
Since the bent pieces in the peripheral part of the shadow grid are positioned on the outer periphery of the shadow grid, and the peripheral part is positioned on the flat surface of the outer peripheral side structure, the shadow grid is used for the outer peripheral side structure and the control grid or The cathode can be mounted easily and quickly while keeping a predetermined distance from the cathode, and the shadow grid is welded to the flat surface through the welding hole so that the mounting state can be stably fixed. Also, by attaching a shadow grid to the cathode, the electron gun can be downsized.

Further, the counterbore on the flat surface according to the invention of claim 2 is fitted so as to position the peripheral portion of the shadow grid, so that a predetermined distance is maintained with respect to the control grid and the cathode. The fitting state of these shadow grids and the outer peripheral side structure can be maintained, and the welding state thereof can be stably fixed.

Further, since the shadow grid and the outer peripheral side structure in the invention of claim 3 are both made of molybdenum alloy, they facilitate mutual welding, and since they have the same thermal expansion coefficient, they are displaced by mutual thermal deformation. ， Prevent the occurrence of displacement.

Furthermore, the outer peripheral structure in the invention of claim 4 is made of tungsten, but by using a brazing material such as ruthenium-molybdenum or platinum, welding to a shadow grid made of molybdenum alloy is performed. To be able to do it.

Furthermore, the heat insulating layer in the invention of claim 5 functions to reduce the thermal influence from the cathode to the shadow grid and prevent the deterioration of the operating performance and durability of the shadow grid.

Further, the brazing filler metal according to the invention of claim 6 is fixed in a state where the shadow grid is attached to the cathode itself so as not to cause positional displacement or abnormal deformation.

[0031]

【Example】

Example 1. An embodiment of the invention of claim 1 will be described below with reference to the drawings. In FIG. 1, reference numeral 15 is a cathode, which is composed of a cathode substrate 16 and an outer peripheral structure 17 that surrounds the cathode substrate 16. The outer peripheral structure 17 is made of a molybdenum alloy, and is brazed in advance with a high melting point brazing material 18 such as ruthenium-molybdenum on the cathode substrate 16 and the inner peripheral surface on the electron emission surface side, or although not shown. Welded by beam welding.

Reference numeral 19 is a shadow grid formed in a cap shape, and a flat surface 19a around the shadow grid is provided with a welding hole 20 by etching or the like in advance as shown in FIG. A peripheral portion of the surface 19a is a bent piece 19b bent downward in an L shape. In addition, the flat surface 19 of the shadow grid 19
In the inner diameter portion from a, there is an arc-shaped recess 19c corresponding to the electron emission surface shape of the cathode substrate 16, and this recess 19c has the same grid spoke structure as the conventional one.

Next, the operation will be described. First, the cathode 15
And the shadow grid 19 are fitted with the outer diameter of the outer peripheral structure 17 and the inner diameter of the cylindrical portion of the shadow grid 19, and the flat surface 19a around the shadow grid 19 is placed on the flat surface of the outer peripheral structure 17. To position. Next, the welding holes 20 of the shadow grid 19
Through the laser beam B through the outer peripheral structure 17 and the shadow grid 19 at the flat surface 19a portion.
It is fixed by laser beam welding, etc.

In this case, the shadow grid 1
9 and the outer peripheral side structure 17 of the cathode 15 constitute the invention of claim 3. In the present invention, since the shadow grid 19 and the outer peripheral structure 17 are both made of a molybdenum-based material, the weldability is good.

By doing so, the shadow grid 19 can be easily positioned and fitted,
With respect to the cathode, the entire occupied space can be reduced, and the cathode can be fast and surely fixed without being dislocated, displaced, or deformed.

Example 2. FIG. 3 shows an embodiment of the invention of claim 2. This is because the first embodiment is positioned at the outer diameter of the outer peripheral side structure 17 and the inner periphery of the cylindrical portion of the shadow grid 19 so as to maintain their concentricity, while the flat surface of the outer peripheral side structure 17 is arranged. A circular counterbore 23 is provided in advance, and the outer periphery of the flat portion 19a of the shadow grid 19 is fitted to this so as to be positioned relative to each other. In this case, if necessary, laser welding may be performed along the boundary line between the inner circumference of the spot facing portion 23 and the outer circumference of the flat portion of the shadow grid 19. Further, in this case, a material having a relatively small Ericssen value can be used as the shadow grid 19.

Example 3. In the second embodiment, laser welding is performed along the boundary line between the inner periphery of the spot facing portion 23 of the outer peripheral structure 17 and the outer periphery of the flat portion of the shadow grid 19, but in order to further improve weldability. , Fig. 4
As shown in FIG. 5, a plurality of notches 26 may be provided in advance on the outer periphery of the shadow grid 19 at a certain depth, and the shadow grid 19 may be welded to the outer peripheral structure 17 at this portion. In this case, the notch that vertically penetrates the notch may be a hole.

Example 4. FIG. 5 shows an embodiment of the invention of claim 4. In the third aspect of the invention, the shadow grid 19 and the outer peripheral side structure 17 are both molybdenum alloys, whereas the outer peripheral side structure 17 is tungsten. In this case, the shadow grid 19
Since the weldability of tungsten is inferior in the joining with the brazing material, the brazing material 2 such as ruthenium-molybdenum or platinum is previously formed on the flat surface 17a of the outer peripheral structure 17.
By coating No. 8, these welds are satisfactorily performed and it becomes possible to integrally fix them.

In this case, since the cathode substrate 16 and the outer peripheral side structure 17 are made of the same kind of metal, there is no problem such as displacement or deformation due to a difference in thermal expansion coefficient between them. Further, since the tungsten of the outer peripheral side structure 17 is not impregnated with the impregnating agent, the evaporation amount of the impregnating agent can be reduced,
As a result, the durability of the electron gun can be improved.

Example 5. FIG. 6 shows an embodiment of the invention of claim 5. In this structure, the entire outer peripheral side of the cathode substrate 16 is not joined to the outer peripheral structure 17, but a gap 29 as a heat insulating layer is provided in a portion other than a portion where the upper portion is joined and fixed to each other. By doing so, the cathode base 16 and the outer peripheral side structure 17 are insulated from each other, and the effect of the heat shield of the cathode 15 and the thermal influence on the shadow grid 19 can be suppressed. Here, the above-mentioned joining of the cathode substrate 16 and the outer peripheral side structure 17 may be performed at one end on the electron emitting surface side or at a lower portion thereof.

Example 6. Although a gap 29 is provided between the cathode substrate 16 and the outer peripheral side structure 17 in the fifth embodiment, as shown in FIG. 7, a heat insulating material 30 such as ceramic is interposed at a portion corresponding to the gap. Well, in Example 5 above
Has the same effect as.

Example 7. FIG. 8 shows an embodiment of the invention of claim 6. This uses a cathode 10 which is not divided into two and is the same as the conventional one (impregnating agent is also included in the flat surface), and the flat portion 19a around the shadow grid 19 is used as a coating portion in the flat portion 10a of the cathode 10. Placed through the brazing filler metal 28 of the welding hole 2
Through welding, these flat portions are welded together by a laser beam, etc.
There is an effect that it is possible to easily and inexpensively realize the coupling between the outer peripheral structure 17 and the outer peripheral side structure 17 without displacement or deformation thereof.

Example 8. In the above Examples 1 to 7,
Although a shadow grid based on molybdenum is used, if the shadow grid does not have the bent piece 19b as the 90 ° bent portion as in the second embodiment, as shown in FIG. 9, a shadow grid of tungsten or a tungsten alloy is used. It can also be used as 19. Furthermore, by combining the fourth and seventh embodiments, it is possible to configure all of them with the same kind of metal, so that it is possible to reduce various problems such as deformation of the shadow grid 19 and dimensional deviation due to the difference in thermal expansion of materials.

[0044]

As described above, according to the first aspect of the present invention, the cathode base constituting the cathode and the periphery of the cathode base are provided, and the cathode base is brazed on the electron emission surface side. An outer peripheral side structure and a bent piece formed in the peripheral part of the shadow grid and having an inner periphery joined to the outer peripheral side of the outer peripheral side structure so as to be positionable, are provided in the peripheral part of the shadow grid. A flat surface is formed on the electron emission surface side of the electron emission material of the outer peripheral side structure to form a plurality of welding holes in the peripheral portion of the shadow grid, and the flat portion Since it is configured to be welded to the surface, the structure of the shadow grid support can be simplified and downsized, and adjustment and assembly work such as positioning with respect to the cathode is easy. There is an effect that can be what is obtained.

Further, according to the invention of claim 2, a flat surface is formed on the electron emitting surface side of the outer peripheral side structure so as to position and support the peripheral portion of the shadow grid, and the spot facing portion is formed on the flat surface. Since it was configured to be able to perform welding with the flat surface in the state where the peripheral part of the shadow grid is fitted to this, the shadow grid should be correctly positioned on the flat surface on the cathode side. It is easy and quick to assemble.

Further, according to the invention of claim 3, since the shadow grid and the structure on the outer peripheral side supporting the shadow grid on the flat surface are made of molybdenum alloy, the weldability of these shadow grids to the cathode side is improved. There is an effect that it is possible to obtain a good product and to prevent a dimensional deviation and an abnormal deformation between them due to thermal expansion.

Further, according to the invention of claim 4, between the shadow grid of molybdenum alloy and the outer peripheral structure of tungsten for supporting the shadow grid on the flat surface, ruthenium-molybdenum is welded to each other. Alternatively, since the brazing material of platinum is interposed, the shadow grid can be bonded to the cathode side with good weldability, and dimensional deviation and abnormal deformation due to thermal expansion between these can be reliably prevented. There is an effect that you can get what you can.

Further, according to the invention of claim 5, since the heat insulating layer is provided between the cathode substrate and the outer peripheral side structure, except for the brazed portion, the cathode is formed. There is an effect that the thermal influence from the side to the shadow grid can be mitigated, and therefore the deterioration of the operating performance and durability of the shadow grid can be prevented.

Further, according to the invention of claim 6, a bent piece which is formed in the peripheral portion of the shadow grid and whose inner periphery is joined to the outer periphery of the cathode on the electron emission surface side so as to be positioned, and the shadow grid. A flat surface formed on the electron emission surface side of the cathode is provided so as to position and support the peripheral portion of, and the peripheral portion of the shadow grid,
Since a plurality of welding holes for welding the peripheral portion and the flat surface are provided, and the flat surface of the cathode and the peripheral portion of the shadow grid are welded with a brazing material, the shadow grid is formed on the cathode. Just by mounting and welding, the shadow grid can be positioned and fixed without misalignment or abnormal deformation.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a partially broken electron gun according to an embodiment of the inventions of claims 1 and 3. FIG.

FIG. 2 is a plan view showing a shadow grid in FIG.

FIG. 3 is a front sectional view showing a partially broken electron gun according to an embodiment of the present invention.

FIG. 4 is a plan view showing a shadow grid in FIG.

FIG. 5 is a partially cutaway front view showing an electron gun according to an embodiment of the invention of claim 4;

FIG. 6 is a front sectional view showing a partially broken electron gun according to an embodiment of the invention of claim 5;

FIG. 7 is a front sectional view showing a partially broken electron gun according to another embodiment of the invention of claim 5;

FIG. 8 is a front sectional view showing a partially broken electron gun according to an embodiment of the present invention.

9 is a sectional view showing another embodiment of the shadow grid in FIG.

FIG. 10 is a perspective view showing a conventional electron gun partially broken away.

FIG. 11 is a front view showing another conventional electron gun in a partially cutaway manner.

12 is a plan view showing a shadow grid in FIG.

13 is a cross-sectional view showing a shadow grid in FIG.

[Explanation of symbols]

 1 Heater 5 Control Grid 10 Cathode 10a Flat Surface 15 Cathode 16 Cathode Base 17 Periphery Side Structure 17a Flat Surface 19 Shadow Grid 19b Bending Piece 20 Weld Hole 23 Counterbore 28 Brazing Material 29 Gap (Heat Insulating Layer) 30 Heat Insulating Material (Heat Insulation) layer)

Claims (6)

[Claims] 1. A cathode heated by a heater to emit thermoelectrons, a control grid for controlling the amount of thermoelectrons emitted by applying a positive or negative potential to the cathode, the control grid and the cathode. And an electron gun provided with a shadow grid for preventing the thermoelectrons from directly flowing into the control grid, which is provided between the cathode base constituting the cathode and the periphery of the cathode base, Further, the outer peripheral side structure brazed on the electron emitting surface side of the cathode substrate and the peripheral portion of the shadow grid are formed, and the inner peripheral side of the outer peripheral side structure can be positioned with respect to the outer peripheral side of the electron emitting surface side. Electrons of the outer peripheral side structure so as to position and support the joined bent piece and the peripheral portion of the shadow grid. An electron gun comprising: a flat surface formed on the emission surface side; and a plurality of welding holes formed in a peripheral portion of the shadow grid for welding the peripheral portion and the flat surface. 2. A cathode heated by a heater to emit thermoelectrons, a control grid for controlling the amount of thermoelectrons emitted by applying a positive or negative potential to the cathode, the control grid and the cathode. And an electron gun provided with a shadow grid for preventing the thermoelectrons from directly flowing into the control grid, which is provided between the cathode base constituting the cathode and the periphery of the cathode base, An outer peripheral structure brazed on the electron emission surface side of the cathode substrate, and a flat surface formed on the electron emission surface side of the outer peripheral structure so as to positionally support the peripheral portion of the shadow grid. , The flat surface formed on the flat surface, with the peripheral portion of the shadow grid being fitted. An electron gun provided with a spot facing portion for welding with. 3. A cathode that is heated by a heater to emit thermoelectrons, a control grid that controls the amount of thermoelectrons emitted by applying a positive or negative potential to the cathode, the control grid, and the cathode. And an electron gun provided with a shadow grid for preventing the thermoelectrons from directly flowing into the control grid, which is provided between the cathode base constituting the cathode and the periphery of the cathode base, An electron is characterized in that an outer peripheral structure brazed on the electron emission surface side of the cathode substrate is provided, and the shadow grid and the outer peripheral structure supporting the shadow grid on a flat surface are molybdenum alloys. gun. 4. A cathode heated by a heater to emit thermoelectrons, a control grid for controlling the amount of thermoelectrons emitted by applying a positive or negative potential to the cathode, the control grid and the cathode. And an electron gun provided with a shadow grid for preventing the thermoelectrons from directly flowing into the control grid, which is provided between the cathode base constituting the cathode and the periphery of the cathode base, Further, it is interposed between the outer peripheral structure brazed on the electron emission surface side of the cathode substrate, the shadow grid of molybdenum alloy, and the outer peripheral structure of tungsten supporting the shadow grid on a flat surface. , Provided with a brazing filler metal of ruthenium-molybdenum or platinum for welding these together An electron gun characterized by that. 5. A cathode heated by a heater to emit thermoelectrons, a control grid for controlling the amount of thermoelectrons emitted by applying a positive or negative potential to the cathode, the control grid and the cathode. And an electron gun provided with a shadow grid for preventing the thermoelectrons from directly flowing into the control grid, which is provided between the cathode base constituting the cathode and the periphery of the cathode base, And an outer peripheral side structure brazed on the electron emission surface side of the cathode base, and a heat insulating layer disposed between the cathode base and the outer peripheral side structure, excluding the brazed portion. An electron gun characterized by being provided with. 6. A cathode which is heated by a heater to emit thermoelectrons, a control grid which controls the emission amount of the thermoelectrons by applying a positive or negative potential to the cathode, the control grid and the cathode. An electron gun having a shadow grid that is interposed between the shadow grid and the shadow grid to prevent the thermoelectrons from directly flowing into the control grid. A bending piece whose inner periphery is joined so that it can be positioned relative to the outer periphery of
A flat surface formed on the electron emission surface side of the cathode and a peripheral portion of the shadow grid so as to position and support the peripheral portion of the shadow grid, and weld the peripheral portion and the flat surface to each other. An electron gun comprising a plurality of welding holes to be formed, and a brazing material interposed between the flat surface of the cathode and the peripheral portion of the shadow grid to weld them.