KR0136190Y1 - Anode structure of magnetron - Google Patents

Abstract

The present invention changes the inner and outer radii of two pairs of inner and outer equalization rings disposed in the upper and lower portions of the anode part to attenuate the second and third harmonics, respectively, to absorb the second and third harmonics. In the normal magnetron, the outer pressure equalizing ring 134 mounted at a predetermined distance by filtering one vane 116 adjacent to the upper and lower portions of the vanes 116 disposed in the anode cylinder 112 in the normal magnetron. When the inner radius of R1, the outer radius of R2, and the median radius of the arithmetic mean are RO, 2πR1≤ the wavelength of the second harmonic ≤ 2πR2 (excitation) to absorb the second harmonic in the outer equalization ring 134. In this case, the inner and outer radii R1 and R2 of the outer equalization ring 134 are set to satisfy the wavelength of the second harmonic is represented by 2πR0, and a predetermined inside of the outer equalization ring 134 is set. P1, the inner radius of the inner pressure equalizing ring 132 mounted at a distance When the outer radius is P2 and the median radius based on these arithmetic averages is PO, 2πP1 ≦ wavelength of the third harmonic ≤2πP2 so that the third harmonic is absorbed by the inner pressure suppressing ring 132 (where the wavelength of the third harmonic is 2πP0. It is characterized in that the inner radius and outer radius (P1, P2) of the inner pressure equalizing ring 132 is set to satisfy.

Description

Magnetron anode structure

1 is a partial longitudinal sectional view showing a conventional general magnetron.

Figure 2 is a schematic longitudinal sectional view of the magnetron according to an embodiment of the present invention.

3 is an enlarged plan view of the anode structure in which the first magnetic pole piece and the second magnetic pole piece are removed in FIG.

Figure 4 (a) is a plan view of the outer pressure equalizing ring.

Figure 4 (b) is a graph of the amount of attenuation of the second harmonic with respect to the middle radius between the inner and outer radius of the outer equalization ring.

Figure 5 (a) is a plan view of the inner pressure equalizing ring.

5 (b) is a graph of the attenuation amount of the third harmonic with respect to the intermediate radius between the inner and outer radius of the inner pressure equalization ring.

* Explanation of symbols for main parts of the drawings

101: filament 102,103: upper and lower end hat

106: vane 107,118: metal tube

112: anode body 113, 114: first and second pole pieces

116: vane 117: antenna

132: inner pressure ring 134: outer pressure ring

136: ceramic tube 139: exhaust pipe

The present invention relates to a magnetron used in a microwave heating device such as a microwave oven, and more particularly, the inner radius of two pairs of inner and outer equalization rings respectively disposed on the upper and lower portions of the anode to attenuate the second and third harmonics. It relates to the anode portion of the magnetron in which the outer radius is changed to absorb the second and third harmonics.

In general, magnetrons, or high-frequency oscillators, generate microwaves efficiently, and they are widely used for heating foods, especially in microwave ovens. In addition, safety, high quality, and long life are demanded. Miniaturization of high frequency oscillation apparatus is also pursued by the demand of the trend.

As a typical representative high frequency oscillation apparatus, there is a patent application No. 3669 of 1990, which the applicant has already applied for. In the present invention, as shown in FIG. 1, a plurality of protrusions protruding toward the cathode filament 10 inside the anode cylinder 1 to form a resonance cavity to attenuate a plurality of kinds of harmonic components leaking to the outside of the high frequency oscillation apparatus. Anode vanes 2 are arranged, and the first and second magnetic pole pieces 5 and 6 for magnetic field convergence are arranged opposite to each other at the open ends of the anode cylinder 1. At the same time, the first cylinder 20 for harmonic choke and the second cylinder 21 for harmonic choke are interposed between the first metal tube 18 via an insulating tube 19 made of ceramic. It is hermetically fixed to one end, and at the upper opening end of the anode cylinder 1 in a state in which the flange portion 18a of the first metal tube 18 covers the first pole piece 5 in an airtight manner. Hermetically sealed to generate a fundamental wave of 2450 MHz. In the first metal tube 18, a second metal tube 33 and a third metal tube 34 are fixed.

That is, stretched metal tube 33, the flange portion (33b) on one side of the second toward the outside, the ceiling portion is λ ₂ of the through hole and a second harmonic wavelength (λ ₂₎ of the antenna (24) through One end of the cylindrical portion having a length L1 corresponding to / 4 is integrally connected to the flange portion 18a of the first metal tube 18, and the third metal tube 34 has a flange portion at the bottom thereof. 34b extends to the outside, and the through-hole is also formed in the ceiling of the second metal tube 33 through which the antenna 24 penetrates, and? Of the _third harmonic wavelength λ ₃ . _One end of the cylindrical portion 34a having a length L2 of 3/4 is connected to the flange portion 34b. Here, the space constituted by the cylindrical portion of the first metal tube 18 and the cylindrical portion 33a and the flange portion 33b of the second metal tube 33 serves as the first choke means 40. In addition, the space constituted by the cylindrical portion 33a of the second metal tube 33 and the cylindrical portion 34a of the third metal tube 34 acts as the second choke means 41. The first choke means 40 is set to a length L1 to attenuate harmonics lower than that of the second choke means 41.

Further, in order to shield the leakage of harmonics, a first cylinder 20 having a height L3 from the upper end of the insulated tube 19 is welded to the upper opening of the insulated tube 19.

However, in the high frequency oscillator configured as described above, the harmonic components radiated to the outside of the high frequency oscillator cannot be sufficiently shielded from the microwave output including the harmonic components corresponding to the fundamental waves of the 2450MHZ band and the integral multiple of the fundamental waves. There is a problem that the harmonic components leaked from cause TV, radio, radio interference.

In addition, the hot electrons emitted from the filament 10 to the positive electrode vanes 2 form an electric field, and since the hot electrons collide with the positive electrode vanes 2 and are reflected, the upper part serving as the positive electrode vanes 2 and the electron escape preventing plate. And 30 MHZ in the cavity resonant region 7 composed of the first and second pole pieces 6, 5, the anode vanes 2, and the anode cylinder 1, passing through between the lower end hats 11, 12. In addition to the problem that radio frequency interference noise of ~ 300MHZ band is generated, it may cause disturbance of TV, radio, and wireless communication.In addition, second and third metal tubes (1) 33) (34) has to be manufactured separately, and spaces to be arranged are required, and there are various problems such as a complicated structure, a reduction in manufacturing cost, and no miniaturization.

Accordingly, the present invention has been made to solve the various problems described above, and an object of the present invention is to shield at least two types of first and second harmonic components leaking to the outside of the magnetron, and at the same time, the structure can be simplified and miniaturized. In addition, the present invention provides a magnetron anode structure capable of reducing the manufacturing cost.

In order to achieve the above object, the anode structure of the magnetron according to the present invention includes a filament for emitting hot electrons, upper and lower end hats fixed to both ends of the filament and disposed to prevent radiation of hot electrons in the direction of the central axis thereof; And a funnel shape that forms a positive electrode cylinder having a plurality of vanes disposed so as to form a resonant cavity near the center by surrounding the filament outside, and a magnetic path that is uniformly condensed in the working space in the opening of the anode cylinder. A pair of first and second magnetic pole pieces forming a pair, a metal tube disposed in the funnel-shaped first and second magnetic pole pieces, respectively, to seal the inside of the anode cylinder with a vacuum, and the metal tube on the output side. The exhaust pipe disposed on the upper part of the ceramic tube and one end is fixed to the exhaust pipe and the other end is fixed to the vane. In a magnetron having an antenna for outputting high frequency oscillated in the resonant cavity, the inner radius of the outer equalization ring mounted at a predetermined distance by filtering one vane adjacent to the upper and lower portions of the vanes disposed in the anode cylinder is R1, If the outer radius is R2 and the median radius of the arithmetic mean is RO, 2πR1≤the wavelength of the second harmonic≤2πR2 so that the second harmonic is absorbed by the outer equalization ring, where the wavelength of the second harmonic is 2πR0. The inner radius and outer radius R1 and R2 of the outer equalization ring are set so as to satisfy the above), and the inner radius of the inner pressure equalizing ring mounted at a predetermined distance inside the outer pressure reducing ring is set to P1 and outer radius. When P2 and the median radius of these arithmetic averages are PO, 2πP1≤3rd harmonic wavelength≤2πP2 (here, the third harmonic wavelength is expressed as 2πP0) so that the third harmonic is absorbed by the inner equalization ring. satisfied Characterized in that a key set of inner radius and an outer radius (P1, P2) of the inner apring to bacteria.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic longitudinal sectional view of the magnetron according to an embodiment of the present invention, and FIG. 3 is an enlarged plan view of the anode structure in which the first and second pole pieces are removed in FIG. 2, and FIG. 4 (a) (B) is a measurement graph of the attenuation amount of the second harmonic with respect to the intermediate radius between the inner radius and the outer radius of the outer equalization ring, and FIG. 5 (a) is the inner equalization ring 5B is a measurement graph of the attenuation amount of the third harmonic with respect to the middle radius between the inner radius and the outer radius of the inner pressure equalizing ring. Here, the same reference numerals are attached to the same parts as those in FIG.

2 and 3, reference numeral 112 denotes an anode cylinder formed in a cylindrical shape by, for example, a copper plate or the like, and a plurality of vanes 116 forming a plurality of resonant cavities on the inner surface of the anode cylinder 112. This anode is arranged, and the anode body 112 and the vanes 116 constitute an anode portion. In addition, a working space is formed near the central axis of the anode body 112 by the tip portions of the plurality of vanes 116, and in this working space, for example, thorium (Th) to emit hot electrons. The filament 101 wound around the tungsten (W)) in a spiral shape is arranged. The upper and lower end hats 102 and 103 are fixed to both ends of the filament 101 so as to prevent radiation of hot electrons in the direction of the central axis, which is a loss current that does not contribute to oscillation, and the bottom surface of the lower end hat 103. The outer lead wire 127, which is an outer support, is welded and fixed, and the central lead wire 135, which is a central support, is formed of the upper end hat 102 through a through hole (not shown) formed near the center of the lower end hat 103. Welded to the lower end. Here, the center lead wire 135 penetrates non-contact with the lower end hat 103 and the filament 101, and these lead wires 127 and 135 are made of molybdenum, thereby providing an operating current to the filament 101. To supply.

In the drawing, reference numerals 113 and 114 are funnel-shaped first and second pole pieces that are fixed to both openings of the anode cylinder 112 to form a magnetic path uniformly converging the magnetic flux in the working space. Bending and fixing the outer edges of both ends remaining after being seated at the cutouts inside the both ends of the anode cylinder 112, the airtight welding is fixed, the upper and lower portions of the funnel-shaped first and second pole pieces (113, 114) Metal tubes 118 and 106 for sealing the inside of the anode cylinder 112 by vacuum are respectively fixed to the middle portions of the first and second pole pieces 113 and 114 or by the end portions of the anode cylinder 112 by welding. The ring-shaped permanent magnets 120 and 121 are disposed on the outer surfaces of the metal pipes 118 and 106 at a predetermined distance, respectively. An output side ceramic tube 136 formed in a ceramic cylindrical shape is fixedly connected to the upper opening end of the metal tube 118 by welding or the like, and the upper end of the output side ceramic tube 136 is made of copper. The exhaust pipe 139 is fixed to the other side, and the other side of the antenna 117 coupled to one side to the vane 116 is welded near the inner central portion of the exhaust pipe 139 to output high frequency oscillated in the resonance cavity. The outer surface of the exhaust pipe 139 is covered with an antenna cap 137 that protects the welded portion of the exhaust pipe 139 and prevents sparking due to electric field concentration, and acts as a high frequency antenna and draws a high frequency output to the outside. have.

In addition, on the outer circumferential surface of the anode cylinder 112, a plurality of aluminum heat sinks 115 extending in the radial direction of the tube are fitted and arranged by a clamp member 124 fixed to a yoke, which will be described later. The permanent magnets 120 and 121 are covered by yokes 122 and 123 for forming a porcelain. In addition, a first gasket 129 formed of a metal mesh or the like between the openings of the upper yoke 122 of the permanent magnet 120 on the output side to prevent radio wave leakage at a high frequency is interposed between the second gasket 138. Are arranged.

The lower ends of the outer and center lead wires 127 and 135 are electrically connected to the first and second external connection terminals 130 and 131 via the first and second metal plates 132 and 133 formed on the insulating ceramic 141, respectively. Connected.

Next, with reference to FIG. 3, FIG. 4, and FIG. 5, the structure of the anode part which is the summary of this invention, and its effect are demonstrated.

As described above, a plurality of vanes 116 are disposed in the anode cylinder 112 constituting the anode portion in the axial direction thereof, and capacitances of the vanes 116 can be changed in the upper and lower portions near the tip end side thereof. The inner and outer equalization rings 132 and 134 are disposed so as to filter the vanes 116 to each other. As such, if the vane 116 is disposed every other and the intermediate radius RO of the outer equalization ring 134 absorbing the second harmonic is changed from 8.75 to 10.75 mm, the fourth degree is as shown in FIG. Attenuation amount (b) of (b) generally exhibits a parabolic shape in which the vertex is downward, and the second harmonic is absorbed by the outer equalization ring 134. Here, when the inner radius of the outer pressure equalizing ring 134 is set to R1 and the outer radius is set to R2, the median radius RO of these calculated average values is (R1 + R2) / 2, and the median radius RO is Multiplying 2 [pi] results in the intermediate circumferential length L of the outer equalizing ring 134 connecting the intermediate point of the outer equalizing ring 134, and the wavelength λ ₂ of the second harmonic is the intermediate circumferential length L. In order to absorb the second harmonic, R1 and R2 may be set so as to satisfy the wavelength? Λ ₂ ≤ 2πR2 range of the second harmonic.

In addition, in order to absorb the third harmonic by the inner pressure equalizing ring 132, when the inner radius of the inner pressure equalizing ring 132 is P1 and the outer radius is P2 in FIG. 5 (a), between these inner and outer diameters. The median radius PO of the medial radius PO, i.e., the median radius PO by the arithmetic mean of the medial radius P1 and the exterior radius P2 of the medial pressure equalization ring 132, is equal to (P1 +). P2) / 2, and the intermediate circumferential length of the inner side pressure ring 132 connecting the middle point of the inner side pressure ring 132 becomes 2πP0. In the wavelength (λ ₃₎ of the third harmonic will have a circumferential length (L ') and a wavelength (λ ₃₎ in the range of ≤2πP2 2πP1≤ third harmonic is the same of the inner bacteria apring 132, the P1 and P2 You can set it.

FIG. 5 (b) shows the attenuation amount of the third harmonic in dB when the median radius PO of the inner side equalization ring 132 disposed every other vane 116 is changed to 5.5 to 7.5 (mm). A graph measured in units.

As described above, according to the anode structure of the magnetron according to the present invention, a pair of inner and outer equalization rings are provided for each of the vanes adjacent to the upper and lower portions of the plurality of vanes disposed in the anode cylinder. And the arithmetic mean of the inner and outer radius of these outer equalization rings, i.e., the intermediate circumferential length (L) with respect to the intermediate radius, where the circumferential length is equal to the wavelength of the second harmonic (λ ₂ ). By setting larger than the circumferential length to the inner radius of the outer equalization ring and smaller than the circumferential length to the outer radius of the outer equalization ring, the second harmonic can be completely absorbed by the outer equalization ring, and the inner radius of the inner equalization ring And the arithmetic mean of the outer radius, i.e., the intermediate circumferential length L 'for the middle radius (where the circumferential length is equal to the wavelength λ ₃ of the third harmonic) than the circumferential length for the inner radius of the inner equalization ring. Since the third harmonic can be completely absorbed by the inner side equalization ring by setting it larger and smaller than the circumferential length with respect to the outer radius of the inner side equalization ring, the second metal tube acting as a choke in the first metal tube as in the prior art, and Since there is no need to install a third metal tube, the structure can be simplified and downsized, and the manufacturing cost of these components can be reduced, and the structure is simple and the assembly labor can be reduced, thereby reducing the manufacturing cost. It is a very practical design.

Claims (1)

Filaments 101 for emitting hot electrons, upper and lower end hats 102 and 103 that are attached to both ends of the filaments 101 and disposed to prevent radiation of hot electrons in the direction of the central axis thereof, and the filaments Anode cylinder 112 in which a plurality of vanes 116 are disposed so as to surround the outer portion 101 to form a resonant cavity near the center portion, and is fixed to an opening of the anode cylinder 112, respectively, to have a uniform magnetic flux in the working space. Are disposed on a pair of funnel-shaped first and second pole pieces 113 and 114 and a funnel-shaped first and second pole pieces 113 and 114 respectively to form a path for converging them. A metal pipe 118 and 106 for sealing the inside of the anode cylinder 112 with a vacuum, an exhaust pipe 139 disposed on an upper portion of the ceramic pipe 136 disposed on the metal pipe 118 on the output side, and the exhaust pipe One end is fixed to (139) and the other end is fixed to the vane 116 to the ball In a magnetron having an antenna 117 for outputting high frequency oscillated in a vacuum cavity, the vane 116 adjacent to the upper and lower portions of the vane 116 disposed in the anode cylinder 112 is disposed at a predetermined distance from each other. When the inner radius of the outer equalization ring 134 is set to R1, the outer radius is R2, and the median radius of the arithmetic mean is RO, 2πR1 ≦ 2nd harmonic to absorb the second harmonic from the outer equalization ring 134. The inner radius and outer radius (R1, R2) of the outer equalization ring 134 is set to satisfy the wavelength ≤ 2πR2 (wherein, the wavelength of the second harmonic is represented by 2πR0), and the outer equalization ring 134 When the inner radius of the inner pressure equalizing ring 132, which is mounted at a predetermined distance inside the inner side, is P1, the outer radius is P2, and the median radius based on these arithmetic averages is PO, the third harmonic is the inner harmonic ring 132. 2πP1 ≤ wavelength of the third harmonic ≤ 2πP2 (where the third harmonic A magnetron anode structure, characterized in that the inner and outer radii (P1, P2) of the inner side equalization ring 132 are set to satisfy the wavelength).