JPH0556615B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetron cathode assembly, and more particularly to a magnetron cathode assembly in which the vibration resistance of a filament is improved.

[Background of the invention]

FIGS. 1A and 1B are a cross-sectional configuration diagram of a main part showing an example of a conventionally used magnetron cathode assembly, and a -' cross-sectional view thereof. In the figure, a filament 1 disposed at the center of the tube axis of the magnetron that emits thermionic electrons is sandwiched between an upper end shield 2 and a lower end shield 3 that prevent thermionic electrons from deviating in the tube axis direction. A center lead 4 and side leads 5 are connected to the upper end shield 2 and lower end shield 3, respectively.
Furthermore, a terminal 6 is soldered with silver copper to the lower ends of the center lead 4 and side leads 5 together with a stem ceramic 7. Further, an insulating spacer 8 made of an insulator and having a hole through which the two leads 4 and 5 are inserted is disposed in the center lead 4 and the side leads 5. , 5 resonate and prevent the filament 1 from being broken. The spacer 8 is positioned by welding a sleeve 9 to either the center lead 4 or the side leads 5.

In this way, the vibration damping effect of the center lead 4 and side leads 5 is measured by the spacer 8, but this is because the resonance points are different due to the difference in length of the center lead 4 and side leads 5. It is caused by In addition, in order to improve the thermionic radiation efficiency of the filament 1, its surface is carbonized and becomes extremely brittle, and the center lead 4
Alternatively, if either side lead 5 vibrates, the filament 1 cannot follow the deformation and breaks. Therefore, the spacer 8 connects the center lead 4 and the side leads 5, and functions to provide vibration isolation to each other. However, when actually observing the resonance situation, the center lead 4 has a longer length and a lower resonance frequency, so the amplitude becomes larger. Here, for vibrations in the direction of arrow A-A' as shown in figure b,
Spacer 8 has a sufficient vibration-proofing effect, but arrow B
For vibration in the -B' direction, the spacer 8 only has the center lead 4 and the side leads 5 fitted together, so it rotates in the direction of arrow C-C' around either lead that is not vibrating. It moves like it does.

As explained above, in the conventional magnetron cathode structure, the spacer 8 for vibration isolation has directionality, and it is not possible to obtain one with sufficient mechanical strength. Therefore, it is necessary to increase the diameter of the lead using an expensive material such as molybdenum to maintain rigidity, or to form a metallized film around the lead through hole of the spacer 8 made of an insulator, and use an expensive silver-copper brazing material. Measures such as fixing leads 4 and 5 have been proposed, but all of them lead to an increase in the price of the magnetron.
Undesirable.

[Purpose of the invention]

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a magnetron cathode structure that can provide excellent vibration damping effects at a low cost.

[Summary of the invention]

In order to achieve this purpose, the magnetron cathode structure according to the present invention includes an insulating spacer,
The through hole for inserting the side lead is circular, the through hole for inserting the center lead is oval or rectangular in cross section, and almost the entire area of the center lead bent into a crank shape is held between the center lead and the side lead in engagement. This is what I did.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 2 is a diagram showing an embodiment of a magnetron cathode structure according to the present invention. FIG. 2a is a cross-sectional view of a main part, and FIG. The same reference numerals are given and the explanation thereof will be omitted. In the figure, a spacer 11 made of, for example, a ceramic molded body as an insulator is installed at a position where its end on the lower end shield 3 side is almost in contact with the lower end shield 3, and the side lead 5
The longitudinal direction of the through hole 11a, which has a circular cross section through which the center lead 4 is inserted, coincides with the bending width w of the crank-shaped bent portion 4a of the center lead 4, and the center lead is inserted so as to accommodate almost the entire area of the bent portion 4a of the center lead 4. A straight through hole 11b that penetrates from the lower end shield 3 side to the stem ceramic 7 side and has a width that is almost the same as the diameter of the bent portion 5 and has a width that is almost the same as the bent width of the bent portion 4.
The center lead 4 and the side leads 5 are engaged and held together.

In other words, the side leads 5 are located near the lower end shield 3 of the center lead 4 in a direction away from the side leads 5 and are spaced apart from the side leads 5 on the stem ceramic 7 side.
The insulating ceramic spacer 11 has a bent portion 4a which is bent to be larger than the distance between the filament 1 and the lower end shield 3. A straight circular through hole 11a having a diameter almost the same as the diameter of the center lead 5 and a straight circular through hole 11a having a width almost the same as the diameter of the center lead 5 and accommodating almost the entire area of the bent part 4a of the center lead 4.
It has a straight penetrating shape 11b having approximately the same dimension as the bending width dimension of a and penetrating from the lower end shield 3 side to the stem ceramic 7 side, through which the side lead 5 at the end on the stem ceramic 7 side is inserted. Sleeve 9 fixed in contact with circular through hole 11a
The configuration is equipped with the following.

According to such a configuration, when the center lead 4 tries to move in the direction of the arrow C-C', the center lead 4 is twisted, and a drag force is generated to prevent the center lead 4 from swinging in the direction of the arrow C-C'. That will happen. Here, in the example shown in FIG. 1, the movement of the spacer 11 in the axial direction is prevented on the one hand by the melted portion 3a of the side lead 5 caused by butt welding of the side lead 5 and the lower end shield 3. The other end is stopped by a sleeve 9, but instead of this sleeve 9, for example, a projection (not shown) may be provided on the center lead 4 and stopped.

[Effects of the Invention] As explained above, in the magnetron structure according to the present invention, the ceramic spacer that engages the center lead and the side leads is installed substantially in contact with the lower end shield of the filament, and the crank-shaped bent portion of the center lead Since it has a through hole that holds the spacer in place, it can provide vibration isolation effects against vibrations in all directions, and it also has a simple structure that does not impair the ease of manufacturing the spacer itself. It has the extremely excellent effect of being able to obtain a magnetron at a low price.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining an example of a conventional magnetron structure, and FIG. 2 is a diagram for explaining an embodiment of a magnetron cathode structure according to the present invention. 1... Filament, 2... Upper end shield, 3... Lower end shield, 3a... Melting part, 4... Center lead, 4a... Bent part, 5... Side lead, 6... Terminal, 7 ... Stem ceramic, 9 ... Sleeve, 11 ... Ceramic spacer, 11a ... Circular through hole, 11
b...Oval or rectangular through hole.

Claims (1)

[Claims] 1. A filament 1 that emits thermoelectrons, an upper end shield 2 and a lower end shield 3 fixed to the upper and lower ends of the filament, and a center lead 4 whose one end is connected and fixed to the upper end shield. , a side lead 5 with one end connected and fixed to the lower end shield, an insulating ceramic spacer 11 into which the center lead and side leads are inserted, and a stem to which the other ends of the center lead and side leads are connected and fixed. In the magnetron cathode structure having a ceramic 7, the center lead 4 is located near the lower end shield 3 in a direction away from the side leads 5, and on the side of the stem ceramic 7, the distance from the side leads 5 is the same as that of the lower end shield. The insulating ceramic spacer 11 has a bent portion 4a that is bent to be larger than the distance from the side lead 5 on the third side, and the insulating ceramic spacer 11 has an end portion on the filament 1 side in contact with the lower end shield 3. A diameter of the center lead 5 that accommodates a straight circular through hole 11a having approximately the same diameter as the diameter of the side lead 5 through which the side lead 5 is inserted, and a diameter of the center lead 5 that accommodates almost the entire area of the bent portion 4a of the center lead 4. and a straight through hole 11b penetrating from the lower end shield 3 side to the stem ceramic 7 side and having almost the same width as the bending width dimension of the bending part 4a, A magnetron cathode structure comprising a sleeve 9 fixed in contact with a circular through hole 11a at the end of the ceramic 7 through which the side lead 5 is inserted.