JPH088068B2 - Cathode structure for magnetron - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cathode assembly of a direct heating magnetron used in a microwave oven or the like.

2. Description of the Related Art A cathode assembly of a direct heating type magnetron is constructed, for example, as shown in FIGS. 4 and 5, and has a spiral cathode 1 made of thorium tungsten and a first cathode provided at both ends of the cathode 1. And the second end hats 2 and 3, and the first lead wire 4 whose tip is fixed to the first end hat 2.
A second lead wire 5 having a tip end fixed to the second end hat 3 without penetrating the first end hat 2 and the cathode 1, and the first and second lead wires 4, 5. Has two holes through which the upper surface of the first stem lead wire 4 is in contact with the bulging protrusion 4a formed on the first stem lead wire 4, and an insulating spacer 6 for regulating the spacing between the lead wires, and a lower surface of the insulating spacer 6 It is provided with a cup-shaped choke member 7 which is in contact with and attached to the second lead wire 5, and a cathode terminal lead-out stem 8.

The cathode 1 is fragile, but the insulating spacer 6 has both lead wires
Since the mutual intervals of 4 and 5 are always kept constant, there is almost no risk that the cathode 1 is distorted even if an external impact is applied.
On the other hand, the choke member 7 is for preventing the microwave generated in the magnetron tube from leaking to the stem 8 side, and has a depth corresponding to an electrical length of about a quarter of the fundamental wavelength of the microwave. And surrounds a part of the lead wire 5. The hole 7a provided in the choke member 7 is an escape hole for the first lead wire 4. Further, the first and second lead wires 4, 5 penetrating the bottom plate portion of the cup-shaped insulator forming the stem 8 are hermetically sealed to the bottom plate portion of the stem insulator by the terminal pieces 9, 10. The eyelet-shaped metal tube 11 sealed at the open end of the stem insulator serves as a tray for the anode assembly (not shown).

Problems to be Solved by the Invention In the conventional cathode assembly having such a structure, the choke member 7 prevents the microwave output from leaking to the stem 8 side through the second lead wire 5, as described above. However, when the choke member 7 is attached to the second lead wire 5 by a method such as electric welding, the choke member 7 comes into contact with the first lead wire 4 if the direction of rotation is inappropriate. May cause a short circuit accident, or the desired choke effect may not be obtained satisfactorily. Therefore,
The work of attaching the choke member 7 becomes very troublesome, which is one of the factors that hinder the improvement of manufacturing efficiency.

Means for Solving the Problems The present invention has been made in order to eliminate such a conventional inconvenience. According to the present invention, the choke member is provided with a guide hole, and the insulating spacer is inserted into the guide hole. Have a projecting edge.

Operation With this structure, the insulating spacers, whose rotational directions are determined by penetrating the first and second lead wires, regulate the rotational direction of the choke member. The rotational direction of the choke member immediately before being fixed to the second lead wire is naturally determined, and the positioning with respect to the second lead wire can be accurately and simply obtained. Further, the positional relationship between the direction of rotation of the choke member and the first lead wire is also predetermined, so that it is possible to prevent the two from approaching each other and causing a short circuit or other trouble.

EXAMPLES Next, the present invention will be described in detail with reference to the examples shown in the drawings.

The cathode structure shown in FIG. 1 is different from the conventional cathode structure shown in FIG. 4 in that the insulating spacer 12 for regulating the lead wire interval, which is made of ceramic, has a guide edge 12a. The cup-shaped choke member 13 has a guide hole 13b in addition to the clearance hole 13a for the first lead wire 4, and the guide flange 12a is inserted into the guide hole 13b as shown in FIG. The insulating spacer 12 is molded into a shape as shown in FIG.

The guide hole 13b is formed to be slightly larger than the cross-sectional shape of the tip portion of the projecting edge 12a, but the first and second lead wires are formed.
The direction of rotation of the insulating spacer 12 in which the holes 4 and 5 penetrate the two holes depends on the arrangement direction of the lead wires 4 and 5.
Therefore, the positional relationship between the first lead wire 4 and the choke member 13 which is skewered by the second lead wire 5 and whose rotational direction is determined based on the projecting edge 12a of the insulating spacer 12 is also predetermined. In this state, the choke member 13 may be fixed to the second lead wire 5 by welding or the like.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, the choke member can be accurately and easily attached to a predetermined lead wire in a predetermined rotation direction without using a complicated jig and without increasing the number of parts. It can be installed and quality and assembly efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of a cathode assembly embodying the present invention, FIG. 2 is a perspective view of an essential part of the cathode assembly, FIG. 3 is a perspective view of an insulating spacer of the cathode assembly, and FIG. FIG. 5 is a side sectional view of the cathode assembly, and FIG. 5 is a perspective view of a part of the cathode assembly. 1 …… Cathode, 2,3 …… End hat, 4,5 …… Lead wire,
12 ... Insulating spacer, 12a ... Edge, 13 ... Choke member, 13b ... Guide hole.

Claims (1)

[Claims] 1. A spiral cathode, first and second end hats provided at both ends of the cathode, a first lead wire having a tip end fixed to the first end hat, and a first end hat. The end-hat and cathode of the second without penetrating
Second lead wire whose tip is fixed to the end hat of
It is provided with a lead wire interval regulating insulating spacer having two holes for inserting the first and second lead wires, and a cup-shaped choke member attached to the second lead wire in contact with the insulating spacer. The cathode assembly for a magnetron, wherein the insulating spacer has a projecting wire for guiding into the guide hole of the choke member.