JP2001195993A - Magnetron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetron which can maintain a cavity resonance property as in prior arts, the cavity resonance property may be changed in the case the size is reduced by reducing a diameter of a cylinder shaped anode body. SOLUTION: This magnetron includes an anode vacuum container having a plurality of banes being arranged radially in a cylinder shaped anode body, a cathode part being disposed on the central axis of the container, an antenna for emitting a microwave to outside. Projected members directed to the central axis of the container are jointed to an inner periphery surface of the cylinder shaped anode body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a magnetron. More specifically, the present invention relates to a magnetron used for a microwave heating device such as a microwave oven or a radar.

[0002]

2. Description of the Related Art As shown in FIGS. 4 and 5, for example, a magnetron includes a plurality of cylindrical anode bodies 51 and a plurality of sheets formed on the inner peripheral surface of the cylindrical anode bodies 51 radially toward the central axis of the anode body 51. An anode vacuum container 53 in which a vane 52 is disposed, and a top hat 54 disposed on a central axis of the container 53.
a, a cathode portion 55 composed of an end hat 54b and a filament 54c, surrounded by two adjacent vanes 52 and the inner peripheral surface of the anode body 51, and generated in a space forming a cavity resonator, for example, of 2450 MHz. It is composed of an antenna 56 and an antenna ceramic 57 for extracting microwaves to the outside. In such a magnetron, thermoelectrons emitted from the filament 54c circulate in the working space of the cavity formed between the vane 52 and the filament 54c, and oscillate microwaves. This microwave passes through one vane 52,
After being transmitted to the antenna 56 joined to the vane 52, it is emitted to the external space. Reference numerals 58 and 59 denote large and small strap rings connected to every other one of the upper and lower sides of each vane 52. Oxygen-free copper or a material equivalent thereto is used as such a material so as to withstand repeated use as a vacuum tube at a high temperature. In particular, the cylindrical anode body 51 has a magnetron-free amount of oxygen-free copper of 7%.
Since it accounts for 0 to 80%, reducing the diameter of the cylindrical anode body 51 is a desirable method for reducing the size and weight of the magnetron and reducing the cost of raw materials. For this reason, it is often attempted to reduce the diameter of the cylindrical anode body 51 by shortening the radial length of the vane projecting from the inner peripheral surface of the cylindrical anode body 51.

[0003]

However, when the diameter of the cylindrical anode body 51 is reduced, the creepage length Lo of the unit cavity is reduced as shown in FIG. There is a problem that L decreases, the resonance frequency changes, and the conventional high-frequency radio wave characteristics cannot be obtained.

To solve such a problem, there is a magnetron that forms the surface of a cavity resonator in an uneven shape (see Japanese Patent Application Laid-Open No. 1-307147). Even when the magnetron is miniaturized due to a reduction in diameter or the like, the concavo-convex shape makes it possible to approximate the conventional high-frequency radio wave characteristics to some extent. However, since the unevenness is formed by pressing integrally from the oxygen-free copper blank on the surface of the cylindrical anode body and the vane by hobbing, it is difficult to ensure the accuracy of the unevenness, and the height of the unevenness is limited. Therefore, when the size is further reduced by further reducing the diameter, there is a limit in obtaining sufficient high-frequency radio wave characteristics.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a magnetron capable of maintaining the characteristics of a cavity resonator that changes when the size is reduced by reducing the diameter of a cylindrical anode body, as in the prior art. The purpose is to:

[0006]

A magnetron according to the present invention comprises: an anode vacuum container having a plurality of vanes radially arranged in a cylindrical anode body; a cathode portion arranged on a central axis of the container; A magnetron comprising an antenna for emitting microwaves to the outside, wherein a projecting member is joined to an inner peripheral surface of the cylindrical anode body toward a center portion side of the cylindrical anode body. And

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a magnetron according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view of an essential part showing an embodiment of the magnetron of the present invention, FIG. 2 is a transverse sectional view showing a cylindrical anode body in FIG. 1, and FIG. 3 shows a unit cavity resonator in FIG. It is an enlarged view.

As shown in FIGS. 1 and 2, a magnetron according to an embodiment of the present invention includes an anode vacuum vessel 1.
A cathode part 2 arranged on the central axis of the container 1, an antenna 3 and an antenna ceramic 4 for extracting microwaves generated in the cavity to the outside, a cathode support 5a,
5b.

[0010] The anode vacuum vessel 1 has a cylindrical anode body 6.
And a plurality of vanes 7 radially arranged in the anode body 6 and magnetic poles 8 and 9 arranged at upper and lower end portions of the cylindrical anode body 6, respectively. Every other one is electrically short-circuited by an inner strap ring 10 and an outer strap ring 11 which connect the staggered 7 alternately. The cathode part 2 includes an end hat 12 fixed to the tip of the cathode support 5a, a top hat 13 fixed to the tip of the cathode support 5b penetrating the center of the end hat 12, and the end hat 12 and the top hat 13. It consists of a filament 14 wound and supported on the cathode support 5b in between.

In the present embodiment, a projecting member 1 is formed on the inner peripheral surface of the cylindrical anode body 6 toward the center of the cylindrical anode body 6.
5 are joined.

The shape of the projection member 15 is rectangular in the present embodiment, but is not limited to this in the present invention, and may be, for example, triangular or parabolic. . In the present invention, the joining method of the projecting member 15 is not particularly limited. For example, the projecting member 15 is welded or brazed after being mechanically joined to the cylindrical anode body 6 directly or by a concave-convex joining of both. Can be used. in this way,
In the present invention, since the projection member 15 is attached to the cylindrical anode body 6, the height of the projection member 15 can be sufficiently ensured.

Most of the microwave current flowing in the space surrounded by the cylindrical anode body 6 constituting the cavity resonator and the two adjacent vanes 7 is caused by the skin effect, and most of the microwave current flows between the cylindrical anode body 6 and the vane. Focus on the surface of 7.

Here, considering the cavity resonator as an LC equivalent circuit, the creeping length Lo of the inner peripheral surface of the pair of vanes 7 and the cylindrical anode body 6 is equal to L, and the vanes 7 The gap between the strap rings 10, 11 and between the strap rings 10, 11 and the vane 7 corresponds to C.

In the present embodiment, the cylindrical anode body 6 is provided on the inner peripheral surface of the cylindrical anode body 6 in accordance with the degree of diameter reduction of the cylindrical anode body 6.
Since the protruding member 15 is provided toward the center of the
The microwave current flowing on the surface due to the skin effect flows along the inner peripheral surface of the cylindrical anode body 6 and the surface of the protrusion member 15 provided toward the center of the cylindrical anode body 6.
The electrical length of the microwave can be longer than that of a conventional magnetron. That is, since the L component of the unit cavity resonator, which has been reduced by reducing the diameter of the cylindrical anode body 6, can be compensated for by the projection member 15, the conventional high-frequency radio wave characteristics become equivalent. As a result, the size and weight of the magnetron and the cost of raw materials can be reduced.

As shown in FIG. 3, the projecting member 15 is made to protrude toward the center of the cylindrical anode body 6 as much as possible, and its height is made larger than the skin thickness (skin depth) a. Thus, the electrical length of the microwave can be reliably increased.

Further, the width of the projection member 15 is set to 2 of the skin thickness a.
If it is larger than twice, the electrical length of the microwave can be further increased, and the size and weight of the magnetron and the cost of raw materials can be reduced.

[0018]

As described above, according to the present invention,
Since the anode structure such as the cylindrical anode body and the vane can be reduced in size while maintaining the conventional characteristics, the size and weight of the magnetron and the cost of raw materials can be reduced. Therefore, according to the present invention, the magnetron can be space-saving and resource-saving.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of a magnetron of the present invention.

FIG. 2 is a cross-sectional view showing the cylindrical anode body in FIG.

FIG. 3 is an enlarged view showing a unit cavity resonator in FIG. 2;

FIG. 4 is a sectional view of a main part showing an example of a conventional magnetron.

FIG. 5 is a transverse sectional view showing the cylindrical anode body in FIG.

FIG. 6 is an enlarged view showing a unit cavity resonator in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode vacuum container 2 Cathode part 3 Antenna 4 Antenna ceramic 5a, 5b Cathode support 6, 21 Cylindrical anode body 7, 22 Bain 8, 9 Magnetic pole 10 Inner strap ring 11 Outer strap ring 12 End hat 13 Top hat 14 Filament 15 Projection Element

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Noriyuki Murao 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture Inside Sanyo Electric Co., Ltd. (72) Inventor Kazuki Miki 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture No. 5 Sanyo Electric Co., Ltd. (72) Inventor Setsuo Hasegawa 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. 5C029 LL01

Claims (3)

[Claims] 1. An anode vacuum container having a plurality of vanes radially arranged in a cylindrical anode body, a cathode disposed on a central axis of the container, and an antenna for emitting microwaves to the outside. A magnetron comprising: a projection member joined to an inner peripheral surface of the cylindrical anode body toward a center portion side of the cylindrical anode body. 2. The magnetron according to claim 1, wherein a height dimension of the projection member is larger than a skin thickness. 3. The magnetron according to claim 1, wherein the width dimension of the projection member is larger than twice the skin thickness.