JPS62133640A - Microwave tube furnishing electron gun with grid - Google Patents

Abstract

PURPOSE:To make it possible to position a grid at a highly accurate position readily and rapidly when it is installed as a microwave tube, by processing a sign of the position beforehand at the center of the electron discharge surface of a cathode member of a microwave tube. CONSTITUTION:At the center of the electron discharge surface 5 of a cathode 1, a sign hole 6 to indicate the central position is engraved. The diameter of the hole is 0.5mm compared to the cathode diameter 10mmphi, and area ratio of the sign hole to the all electron discharge area is about 25/10,000, the influence to the all electron discharge quantity being negligible although the electron discharge is disturbed by the sign hole engraved. By installing the microwave tube in using the cathode member with such a sign, it is possible to install the grid extremely accurately and readily in unifying the center axes of the cathode and the grid.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a microwave tube that performs pulse operation, and in particular, a grid for modulating the electron beam is provided in front of the cathode, which is the electron source of the microwave tube. relates to a microwave tube equipped with an electron gun loaded with

BACKGROUND OF THE INVENTION Microwave tubes operating in pulsed mode typically have their electron guns loaded with a grid. That is, as schematically shown in a sectional view in FIG. 3, a mesh-like grid 3 supported by a support member 2 is disposed in parallel with the cathode I on the front surface of a cathode I serving as an electron source. The electron beam 3 is configured to perform a pulse operation by intermittent flow of the electron beam 3 by applying a voltage to the electron beam 3 . At this time, in order to keep the pulse modulation power small, grid 3
are arranged at an interval of 0.1 to 1 mm from the cathode 1,
Also, the voltage applied to the grid is usually -1000~1o
It is about oov.

Such an electron emitting surface 5 of the cathode 1 of the microwave tube
The grid 3 usually has a concave shape that is part of a spherical surface, and it is desirable that the grid 3 is disposed at a constant distance from the electron emission surface 5.

In addition, Fig. 4 shows the positional relationship between the cathode 1 and the grid 3 in one child as seen from the grid side, but the central axis of the electron emitting surface 5 of the cathode 1 and the grid 3 must be exactly aligned. is desirable.

That is, if the central axes of the cathode 1 and the grid 3 do not coincide, the electron beam 4 collides with a portion of the outermost portion of the grid 3 that does not have the mesh-like transmission holes 3A. This results in an increase in grid current. Furthermore, since the emission direction of the electron beam 3 after passing through the grid 3 deviates from the central axis of the microwave tube, it may penetrate the high frequency circuit following the electron gun section and cause so-called beam transmission failure. Become.

Therefore, in assembling a microwave tube equipped with a grid-equipped electron gun as described above, it is necessary to align the cathode 1 and the grid 3 with extremely high precision.

The spacing between the cathode 1 and the grid 5 can be kept constant relatively easily by unifying the shape of each, especially the curvature of the spherical surface, in advance when forming each as a component. be able to.

However, since the electron emitting surface 5 of the cathode 1 is formed extremely smoothly, it is very difficult to identify the center of the electron emitting surface 5 in order to align the center axes of the two.

Conventionally, the method used to assemble the cathode 1 and the grid 5 while aligning their central axes is to set the distance between the edge of the cathode 1 and the outer periphery of the grid 2, shown as d in FIG. 4, to the outer periphery of the grid. A method of assembling by measuring at 3 to 4 locations and adjusting them so that they are equal.
Alternatively, high precision can be maintained by mechanically assembling the cathode 1 and the support member 2 of the grid 3 in advance with a precision jig, and then joining the support member 2 and the grid 3. It has been implemented.

Problems to be Solved by the Invention The first method for assembling a microwave tube as described above involves measuring d at several locations for each electron gun and adjusting the grid assembly position based on the results. (This will significantly increase the time required for assembly.Also,
If the precision of forming the edges of the cathode to be assembled is not ensured, high-precision assembly cannot be achieved by this method.

Also, when using the second method, in order to maintain high accuracy in the positional relationship between the cathode and the grid; in addition to the dimensional accuracy of the cathode, grid support member, grid, etc. The jigs used for this require extremely high dimensional accuracy, making the manufacturing costs of each member and jig more expensive, which in turn increases the price of the manufactured microwave tube itself.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to make it possible to easily and quickly align the central axes of the cathode and the grid in assembling a microwave tube equipped with an electron gun with a grid. The purpose of this invention is to provide a structure for a microwave tube.

Means for Solving the Problems The present inventors analyzed the problems of the conventional assembly method.

In other words, in the conventional assembly method, the central axis alignment of the cathode and the grid was determined at the periphery of each member, which required dimensional accuracy and measurement beyond what was originally necessary. . Therefore, the present inventor came up with a structure for a microwave tube in which the electron gun is assembled by directly aligning the center of the grid and the cathode by displaying the center position of the cathode in advance, and completed the present invention.

That is, according to the present invention, as shown in FIGS. 1 and 2, in a microwave tube equipped with an electron gun in which a grid 3 for modulating an electron beam is loaded on the front surface of a cathode 1, A microwave tube is provided which is characterized in that it has a mark 6 or 7 on its electron emission surface 5 indicating the center of the emission surface.

Eaves" The cathode of the microwave tube according to the present invention has a mark indicating the center displayed in advance at the center of its electron emitting surface. This mark is mechanical, for example, as shown in Figure 1.
It can be displayed by using recesses or holes 6 formed on the electron emitting surface 5. In this case, if the liquid holes are made sufficiently small, the effect on the electron emitting surface can be ignored. Further, the mark indicating the center may be a cross-shaped line 7 as shown in FIG.

Such a mark indicating the center of the cathode can be extremely easily and accurately measured and marked during lathe processing when manufacturing the cathode.

If a cathode member having a mark indicating the center of its electron emitting surface as described above is used, when assembling the grid,
By assembling the grid while monitoring the mark representing the center of the electron emitting surface through the mesh of the grid using a microscope or the like, it is possible to align the center of the electron emitting surface of the cathode with the center of the grid extremely accurately. It becomes possible.

Note that, as described above, the mark provided on the electron emitting surface needs to be visually recognized through the mesh of the grid, and its dimensions or size are set with this in mind. On the other hand, since such a mark is placed on the electron emitting surface of the cathode, it must be sufficiently small with respect to the entire electron emitting surface.

EXAMPLES Below, the effects of the present invention will be specifically explained in detail with reference to examples, but it goes without saying that the following examples do not limit the technical scope of the present invention.

Embodiment FIG. 1 is a cross-sectional view of an electron gun of a microwave tube having a structure according to the present invention. A mark 6 is bored in the center of the electron emitting surface 5 of the cathode 1 as a hole to indicate the center position. This hole has a diameter of 0.5 mm with respect to the cathode diameter of 10 mmφ, and in this case, the area ratio of the stamp hole to the total area of the electron emitting surface is approximately 25/10.00.
0, and since no electrons are emitted from this part due to the opening of the hole as a mark, the effect on the total amount of emitted electrons can be completely ignored.

If you assemble a microwave tube using a cathode member with such markings according to the procedure described above, you will be able to assemble the grid very accurately and easily by aligning the central axes of the cathode and the grid. Ta.

Effects of the Invention As detailed above, according to the present invention, by processing a mark indicating the position in advance at the center of the electron emitting surface of the cathode member of a microwave tube, it is possible to extremely easily assemble the microwave tube. It becomes possible to easily and quickly realize highly accurate grid positioning.

The microwave tube having such a structure according to the present invention can eliminate poor transmission of electron beams caused by misalignment of the cathode and grid centers, while also making it easy and quick to assemble the microwave tube. can be done.

Therefore, by stabilizing product performance and improving yield, it is possible to reduce costs.

In addition, speeding up the assembly process also means shortening the time the cathode components are exposed to the atmosphere, and by reducing damage to the cathode due to water vapor, etc., it also achieves even more stable performance of the microwave tube. be able to.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing the structure of the main part of the electron gun of the microwave tube according to the present invention, and FIG. 2 shows the center on the electron emitting surface of the cathode according to the present invention. FIG. 3 is a cross-sectional view schematically showing the configuration of a grid, a cathode, and a grid indicating member of a microwave tube equipped with a conventional grid-equipped electron gun. , FIG. 4 is a diagram showing the positional relationship between the grid and the cathode shown in FIG. 3 as viewed from the electron beam emitting surface side. (Main reference numbers) 1. Cathode, 2. Grid support member, 3.
・Grid, 4. Electron beam, 5. Electron emission surface of cathode, 6.7. Seal indicating the center position of cathode Patent application filed NEC Corporation

Claims (1)

[Claims] (1) In a microwave tube equipped with an electron gun loaded with a grid for modulating an electron beam on the front surface of the cathode, a mark indicating the center of the electron emission surface of the cathode is provided. A microwave tube featuring: