JP3169005B2 - Electron gun and method of assembling the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun serving as an electron source for a microwave tube or the like, and more particularly to an electron gun equipped with a cold cathode as a cathode.

[0002]

2. Description of the Related Art A conventional example of an electron gun 31 equipped with a cold cathode 32 will be described below with reference to FIG.

The cold cathode 32 has a Wehnelt electrode 34 provided on the electron emission surface 33 side. On the other hand, the cold cathode 32
On the back surface opposite to the electron emission surface 33, the emitter electrode 3
5 are provided.

The Wehnelt electrode 34 is fixed and held on a cylindrical support (not shown) disposed on the outer periphery thereof. The emitter electrode 35 is supported by an emitter electrode support (not shown) via a spring 36. The emitter (not shown) of the cold cathode 32 is connected to an external power supply via an emitter electrode 35 and an emitter electrode support, and is supplied with power from the external power supply.

The cold cathode 32 is pressed against a Wehnelt electrode 34 by an emitter electrode support and a spring 36. That is, the cold cathode 32 is supported by being sandwiched between the Wehnelt electrode 34 and the emitter electrode 35.

The Wehnelt electrode 34 is for controlling the direction of the flow (electron flow) of the electrons emitted from the cold cathode 32 and for focusing. The Wehnelt electrode 34 has a hole 37 provided at the center thereof, and the periphery of the hole 37 is a cold cathode 32.
It has a mortar-shaped part 38 which is formed in a mortar-like shape on the side. In the Wehnelt electrode 34, the hole 37 allows an electron flow to pass therethrough, and the tip of the mortar-shaped portion 38 contacts the cold cathode 32.

Further, as shown in FIG. 7, a cold cathode 32 is proposed in which an emitter 40, a gate electrode 41 and a focusing cathode 42 are provided on the surface (electron emission surface 33) of a substrate 39 thereof. ing.

The emitter 40 emits electrons. The gate electrode 41 is provided to generate a strong electric field near the emitter 40 and cause the emitter 40 to emit electrons. The gate electrode 41 is connected to an external power supply (not shown) and is supplied with power from the external power supply. The focusing electrode 42 is connected to an external power supply (not shown) via the Wehnelt electrode 34, and forms an electric field for focusing the electron flow emitted from the cold cathode 32.

The gate electrode 41 is connected to an external power source (not shown) in a space between the upper surface of the Wehnelt electrode 34 and the upper surface of the cold cathode 32.

The gate electrode 41 is pulled out using a bonding wire 43 as shown in FIGS. 6 and 7 or a tab 44 as shown in FIG. 8, and the bonding wire 43 and the tab 44 are welded to the gate electrode 41. are doing.

[0011]

As shown in FIG. 6 and FIG. 7, a bonding wire 43 is used for leading out the gate electrode 41, that is, for supplying power to the gate electrode 41.
Is used, it is necessary to form a loop in order to maintain the strength of the bonding wire 43, and the distance between the upper surface of the Wehnelt electrode 34 and the upper surface of the cold cathode 32 is required to obtain a space for forming the loop. Must be secured.

However, in order to ensure a large distance between the upper surface of the Wehnelt electrode 34 and the upper surface of the cold cathode 32, it is not necessary to simply make the mortar-shaped portion 38 of the Wehnelt electrode 34 deeper. Wehnelt electrode 34
When the mortar-shaped portion 38 is deepened, the distance between the Wehnelt electrode 34 and the focusing electrode 42 increases. Then,
The effect of the electric field on the cold cathode 32 is reduced, and electrons cannot be sufficiently extracted.

As described above, it is necessary to find a compromise between the contradictory requirements of ensuring the storability of the bonding wire 43 and the ease of emitting electrons (Pabiance), so that the degree of freedom in designing the shape of the Wehnelt electrode 34 is increased. Limited.

Referring to the assembling sequence in the case of using the tab 44 as shown in FIG. 8, the tab 44 is first connected to the gate electrode, and then the Wehnelt electrode 34 is connected to the focusing electrode. That is, until the Wehnelt electrode 34 is connected, the cold cathode 32 is connected to the emitter electrode 35 using only the tab 44.
It is something to hold to the side. If Wehnelt electrode 3
This is because, if 4 is connected to the cold cathode 32 first, the distance between the upper surface of the Wehnelt electrode 34 and the upper surface of the cold cathode 32 is small, so that it is difficult to connect the tab 44 to the cold cathode 32.

When the cold cathode 32 is pressed and fixed by the tab 44 from the beginning, if the rigidity of the tab 44 is low, the cold cathode 3
Since the force for holding down the cathode 2 is limited, there is a possibility that the cold cathode 32 cannot be held down sufficiently.

If the cold cathode is pressed by the stiffened tab 44, the connection between the Wehnelt electrode 34 and the focusing electrode may be incomplete.

It is an object of the present invention to provide an electron gun which increases the degree of freedom in designing the shape of the Wehnelt electrode and improves the reliability of the connection between the Wehnelt electrode and the focusing electrode.

[0018]

In order to achieve this object, according to the present invention, the Wehnelt electrode is provided with at least one notch in the outer peripheral portion. Are configured to be connected.

According to this configuration, it is not necessary to increase the distance between the upper surface of the Wehnelt electrode and the upper surface of the cold cathode in consideration of the gate electrode lead-out means. Therefore, the degree of freedom in designing the shape of the Wehnelt electrode is increased.

Further, according to this configuration, as an assembling sequence, after connecting the Wehnelt electrode to the cold cathode focusing electrode,
A gate electrode lead-out means can be connected to the gate electrode at the missing portion of the Wehnelt electrode. Since the cold cathode is pressed and fixed by the Wehnelt electrode from the beginning, the connection between the Wehnelt electrode and the focusing electrode does not become incomplete.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIGS. 1 to 4 show an embodiment of the electron gun of the present invention.

This electron gun 1 has a Ka band (30 GHz band).
It is used for electron tubes.

In the electron gun 1, the emitter 8, the gate electrode 9, and the focusing electrode 10 are formed on the surface of the substrate 11 (the electron emission surface 1).
2) The cold cathode 2 provided in 2), for example, a gate electrode feeding plate 3 as a gate electrode lead-out means for connecting the gate electrode 9 of the cold cathode 2 and an external power supply (not shown) side, the focusing electrode 10 and the outside A Wehnelt electrode 4 for connecting to a power supply (not shown) side, an emitter electrode 5 provided in contact with a back surface of the cold cathode 2 opposite to the electron emission surface 12, and the emitter electrode 5 is connected via a spring 6. And an emitter electrode support 7 for supporting.

Here, the electron gun 1 is housed in a vacuum envelope (not shown) and is kept in a high vacuum environment.

The cold cathode 2 is provided with an anode (not shown) at a position facing the cold cathode.

The emitter 8 provided on the cold cathode 2 is for emitting electrons. The gate electrode 9 is provided to generate a strong electric field near the emitter 8 to emit electrons. The focusing electrode 10 is provided for controlling the direction of electrons emitted from the emitter 8 and focusing the electrons.

The Wehnelt electrode 4 is connected to the focusing electrode 10. The Wehnelt electrode 4 has a hole 13 provided at the center and a mortar-shaped portion 14 provided around the hole 13.
And a missing portion 15 provided on the outer peripheral portion. At least one notch 15 is provided on the outer peripheral portion of the Wehnelt electrode 4, for example, four notches 15 are provided at equal intervals in the circumferential direction. The point that the notch 15 is provided in the Wehnelt electrode 4 as described above is as follows.
This is the most significant feature of the present invention.

The Wehnelt electrode 4 is fixed to and supported by an end face of a first cylindrical support 16 made of metal or the like by welding or the like, and is connected to an external power supply via the first cylindrical support 16. It is connected.

The Wehnelt electrode 4 is made of, for example, a non-magnetic stainless steel having a thickness of 0.5 mm, and has an inner diameter of 2 mm and an outer diameter of 5 mm.
mm and a height of 1 mm.

The gate electrode power supply plate 3 is connected to the gate electrode 9. The gate electrode power supply plate 3 is fixed and supported on an end face of a second cylindrical support 17 made of metal or the like by welding or the like, and is connected to an external power supply via the second cylindrical support 17. Have been. The second cylindrical support 17 is arranged on the inner peripheral side of the first cylindrical support 16.

The gate electrode power supply plate 3 is formed in an annular shape, and at least one projection 18 protruding toward the gate electrode 9 is provided, for example, at equal intervals in the circumferential direction. The gate electrode power supply plate 3 is made of, for example, a non-magnetic Monel plate having a thickness of 0.1 mm.

The gate electrode power supply plate 3 has four projections 1
8 are connected to the gate electrode 9 at the four missing portions 15 of the Wehnelt electrode 4. According to the gate electrode power supply plate 3, electrical connection is possible only by pressing and contacting the gate electrode 9 by the spring force of the projection 18, so that electrical connection can be made in comparison with the case of connection by welding such as a bonding wire. Becomes easier.

The recess 15 of the Wehnelt electrode 4 is provided in such a size that the entire projection 18 of the gate electrode power supply plate 3 can be seen from the outside.
8 may be provided in such a size that the tip of the 8 is hidden by the Wehnelt electrode 4. However, the lacking portion 15 that allows the entire projection 18 to be seen has an advantage that it can be visually confirmed whether or not the gate electrode power supply plate 3 is connected to the gate electrode 9.

The Wehnelt electrode 4 is a gate electrode power supply plate 3
A material having higher rigidity is used, and the cold cathode 2 can be pressed sufficiently.

The order of assembling the electron gun 1 is as follows. After the Wehnelt electrode 4 is connected to the focusing electrode 10 of the cold cathode 2,
The projections 18 of the gate electrode power supply plate 3 are brought into contact with the gate electrode 9 of the cold cathode 2 at the four notches 15 of the Wehnelt electrode 4.

In the electron gun 1 configured as described above, the degree of freedom in designing the shape of the Wehnelt electrode 4 and the connection between the Wehnelt electrode 4 and the focusing electrode 2 are increased as follows. Reliability is improved.

The protrusion 18 of the gate electrode power supply plate 3 is pressed against the gate electrode 9 at the notch 15 of the Wehnelt electrode 4 and connected thereto. According to this, it is not necessary to design a large distance between the upper surface of the Wehnelt electrode 4 and the upper surface of the cold cathode 2 in consideration of the gate electrode power supply plate 3, so that the shape of the Wehnelt electrode 4, particularly The degree of freedom in designing the depth is increased. As a result, for example, by designing the distance between the upper surface of the Wehnelt electrode 4 and the upper surface of the cold cathode 2 to be small, a sufficient paviance can be secured.

After the Wehnelt electrode 4 is connected to the focusing electrode 10, the gate electrode power supply plate 3 is connected to the gate electrode 9. That is, the member that presses the cold cathode 2 against the emitter electrode 5 is the Wehnelt electrode 4 from the beginning. Since the Wehnelt electrode 4 has higher rigidity and a higher spring coefficient than the gate electrode power supply plate 3, the connection between the Wehnelt electrode 4 and the focusing electrode 10 is not incomplete. on the other hand,
Since the gate electrode power supply plate 3 having a low rigidity and a low spring coefficient is used, the protrusion 18 of the gate electrode power supply plate 3 is used.
Satisfactorily comes into contact with the gate electrode 9, and the connectivity is improved.

When a predetermined voltage is applied to each of the first cylindrical support 16, the second cylindrical support 17, and the emitter electrode support 7, the cold cathode 2 emits electrons, It functions as an electron gun 1.

The present invention is not limited to the above-described embodiment, and various modifications can be made.

For example, in the above-described embodiment, the gate lead-out means composed of the gate electrode power supply plate 3 is shown. However, the present invention is not limited to this. For example, as shown in a modification shown in FIG. You may connect.

In this modification, the electron gun 1 is L (1.3G).
Hz) band, which is larger than that of the above-described embodiment. Wehnelt electrode 4 has an inner diameter of 5 m
m, outer diameter 25 mm, height 2 mm.

In this modification, the electron gun 1 is larger than in the above-described embodiment, so that the cold cathode 2 and the anode (not shown)
Is larger than in the above-described embodiment. Therefore, a space enough to allow the loop of the bonding wire 19 can be secured. When the bonding wire 19 is used, the manufacturing cost can be reduced as compared with the gate electrode power supply plate 3 and the like.

[0045]

As described above, according to the present invention, after the Wehnelt electrode is connected to the cold cathode focusing electrode,
Since the gate electrode lead-out means is connected to the gate electrode at the portion where the Wehnelt electrode is missing, the following effects are obtained.

(1) Since the gate electrode lead means is connected to the gate electrode at the missing portion, the degree of freedom in designing the shape of the Wehnelt electrode can be increased.

(2) Further, since the cold cathode is pressed and fixed by the Wehnelt electrode from the beginning, the connection between the Wehnelt electrode and the focusing electrode can be ensured.

(3) Since there is a missing portion, an electrical short circuit between the Wehnelt electrode and the gate electrode is prevented.

(4) Since the gate electrode lead-out means is connected to the gate electrode at the missing portion, the connection operation can be easily performed, and no special jig, device, or skill is required for the connection. .

(5) Since the cold cathode is pressed and fixed by the Wehnelt electrode from the beginning, the gate electrode lead-out means can be reduced in size and weight.

(6) Since the cold cathode is first pressed and fixed by the Wehnelt electrode, the axis alignment between the Wehnelt electrode and the cold cathode, that is, the eccentricity can be easily adjusted.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an electron gun according to an embodiment of the present invention, with a part cut away.

FIG. 2 is a partially enlarged sectional view of the electron gun of FIG.

FIG. 3 is a plan view of the electron gun of FIG. 1;

FIG. 4 is a schematic configuration diagram of the electron gun of FIG. 1;

FIG. 5 is a schematic configuration diagram of a modification of the electron gun of the present invention.

FIG. 6 is a schematic configuration diagram of an example of a conventional electron gun.

FIG. 7 is a partially enlarged sectional view of the proposed electron gun.

FIG. 8 is a schematic configuration diagram of another example of a conventional electron gun.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electron gun 2 cold cathode 3 gate electrode power supply plate (gate electrode drawing means) 4 Wehnelt electrode 5 emitter electrode 6 spring 7 emitter electrode support 8 emitter 9 gate electrode 10 focusing electrode 11 substrate 12 electron emission surface 13 hole 14 mortar-shaped part 15 Missing portion 16 First cylindrical support 17 Second cylindrical support 18 Projection 19 Bonding wire (gate electrode lead-out means)

Claims (6)

(57) [Claims] 1. An emitter for emitting electrons, a gate electrode for emitting electrons by generating a strong electric field near the emitter, and a focusing electrode for focusing the direction of electrons emitted from the emitter are provided on the surface. A cold cathode, a gate electrode leading means for connecting the gate electrode to the external power supply side, and a Wehnelt electrode for connecting the focusing electrode and the external power supply side. An electron gun, wherein at least one missing portion is provided, and a gate electrode lead means is connected to the gate electrode at the missing portion. 2. The electron gun according to claim 1, wherein the Wehnelt electrode has a higher rigidity than the gate electrode lead-out means. 3. The gate electrode lead-out means comprises a gate electrode power supply plate.
An electron gun according to claim 1. 4. The electron gun according to claim 3, wherein the gate electrode power supply plate is provided with at least one protrusion that protrudes toward the gate electrode. 5. The electron gun according to claim 1, wherein the gate electrode lead-out means comprises a bonding wire. 6. The method for assembling an electron gun according to claim 1, wherein the Wehnelt electrode is connected to the cold cathode focusing electrode, and then the gate electrode lead-out means is provided at the missing portion of the Wehnelt electrode. A method for assembling an electron gun.