JP2012069309A - Magnetron and microwave oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a magnetron having excellent characteristics at a low cost.SOLUTION: An anode body structure of a magnetron comprises an anode cylinder 20, 10 pieces of vanes 30, and three pieces of strap rings 41 to 43. The 10 pieces of vanes 30 are bonded to an inner peripheral surface of the anode cylinder 20 and are arranged radially around an axis 22 of the anode cylinder 20. The 10 pieces of vanes 30 are divided into five pieces of first vanes 31 and five pieces of second vanes 32 which are alternately arranged around the axis 22. The first vanes 31 are short-circuited to each other by the first and second strap rings 41 and 42, and the second vanes 32 are short-circuited to each other by the third strap ring 43. An antenna 84 is connected to one of the five pieces of first vanes 31. The first strap ring 41 and the second and third strap rings 42 and 43 are provided on different ends of the vanes 30.

Description

  The present invention relates to a magnetron and a microwave oven using the same.

  The magnetron includes a resonator including an anode structure and a cathode, and oscillates microwaves. The magnetron for microwave ovens oscillates 2450 MHz band (ISM band) microwaves.

  The anode structure includes an anode cylinder, an even number of vanes, and at least two strap rings. The vane is formed in a plate shape and is joined to the inner peripheral surface of the anode cylinder. The even number of vanes are arranged radially at the axial center of the anode cylinder. The even number of vanes are classified into first and second vanes arranged alternately around the axis, and the first vanes and the second vanes are short-circuited by different strap rings. The strap ring serves to equalize the potentials of the shorted vanes.

  The cathode is a spiral filament and is provided in an electron action space surrounded by the free ends of an even number of vanes.

  The magnetron resonator thus configured has a specific resonance frequency. This resonance frequency is greatly influenced by the capacitance between the vane and the strap ring and the capacitance between the plurality of strap rings. Therefore, various proposals have been made for the vane short-circuit structure using the strap ring.

  Patent Documents 1 and 2 include a total of four strap rings, as shown in FIG. 11, two large strap rings 141 and 142 having the same diameter and two small strap rings 143 and 144 having the same diameter. A magnetron is disclosed (hereinafter referred to as “conventional example 1”).

  In the magnetron of Conventional Example 1, the first vanes 31 are short-circuited by the strap ring 143 at the input side end (lower end in FIG. 11), and the output side end (upper end in FIG. 11). ) Is short-circuited by the strap ring 142. The second vanes 32 are short-circuited by the strap ring 141 at the input side end and short-circuited by the strap ring 144 at the output side end. Therefore, the balance between the potential on the input side and the potential on the output side of the vanes 31 and 32 is good. As a result, the magnetron characteristics such as reverse electron impact and load stability are excellent. Therefore, the magnetron of Conventional Example 1 having such a vane short-circuit structure is currently widely used in microwave ovens.

JP 2004-134228 A JP-A-63-98940 JP-A-4-296429

  As described above, the magnetron of Conventional Example 1 including the four strap rings 141 to 144 has excellent characteristics. However, in order to obtain the four strap rings 141 to 144, as shown in FIG. 12, two copper plates 48 each having a length equal to or larger than the diameter of the strap rings 141 and 142 having a large diameter are required. A lot of scrap 46 is produced. As described above, the magnetron of Conventional Example 1 has a low material utilization efficiency and requires a lot of material costs. In addition, it is necessary to join four strap rings 141 to 144 to the vanes 31 and 32 by brazing, and productivity is poor.

  Here, it is conceivable to reduce the number of strap rings in consideration of material costs and productivity. For example, Patent Document 3 discloses a magnetron provided with two large and small strap rings 241 and 242 as shown in FIG. 13 (hereinafter referred to as “conventional example 2”). In the magnetron of the conventional example 2, the first vanes 31 are short-circuited by the small-diameter strap ring 242 at the output-side end portion, and the second vanes 32 are short-circuited by the large-diameter strap ring 241 at the output-side end portion. Has been.

  However, in the structure of Conventional Example 2 in which the strap rings 241 and 242 are provided only on one side of the vanes 31 and 32 in the axis 22 direction, Conventional Example 1 in which two strap rings 241 and 242 are provided on both sides of the vanes 31 and 32 in the axis 22 direction. Compared to the structure, the capacitance of the resonator is small, and the resonance frequency may be as high as several hundred MHz. In such a case, it is necessary to correct the resonance frequency by means such as narrowing the distance between the strap rings 241 and 242 and the vanes 31 and 32 or increasing the cross-sectional area of the strap rings 241 and 242. However, if the distance between the strap rings 241 and 242 and the vanes 31 and 32 is reduced, the brazing material may cause a short circuit between the strap rings 241 and 242 or between the strap rings 241 and 242 and the vanes 31 and 32 during brazing. And productivity deteriorates. Further, when the cross-sectional areas of the strap rings 241 and 242 are increased, the material cost may increase as a result.

  Further, in the structure of the conventional example 2 in which the strap rings 241 and 242 are provided only on the output side of the vanes 31 and 32, it is difficult to adjust the resonance frequency. Normally, the resonance frequency of the anode structure is set to be slightly higher than a desired frequency at the time of assembly in consideration of variations in dimensional accuracy and assembly accuracy of components, and is adjusted after assembly. For this adjustment work, a method of cutting a part of the vane or deforming the strap ring is used. In consideration of productivity, side effects on characteristics and workability of adjustment work, the strap ring is deformed in the axial direction while monitoring the resonance frequency with the antenna derived from the anode structure in the waveguide. Thus, a technique is desired in which the capacitance is increased by narrowing the distance between the strap ring and the vane and adjusted to a desired frequency. However, this adjustment method cannot be used in the structure of the conventional example 2 in which the strap rings 241 and 242 are provided only on the output side of the vanes 31 and 32. Further, if the cross-sectional areas of the strap rings 241 and 242 are large, it is difficult to deform the strap rings 241 and 242 themselves.

  Further, in the structure of the conventional example 2 in which the strap rings 241 and 242 are provided only on one side of the vanes 31 and 32 in the axis 22 direction, the potentials on both sides of the vanes 31 and 32 in the axis 22 direction are unbalanced. Therefore, the magnetron of the conventional example 2 is inferior to the magnetron of the conventional example 1 in characteristics such as electron reverse impact and load stability.

  In addition, a magnetron in which three large, medium, and small strap rings are provided only on one side in the axial direction of the vane is also known (hereinafter referred to as “conventional example 3”). With respect to the characteristics of the magnetron, such as electron reverse impact and load stability, Conventional Example 3 is superior to Conventional Example 2 but inferior to Conventional Example 1. In addition, the large-diameter strap ring of the conventional example 3 needs to be designed larger than the large-diameter strap rings 141 and 142 of the conventional example 1, and as a result, it is difficult to suppress the material cost.

  Furthermore, as shown in FIG. 14, a magnetron including two strap rings 341 and 342 having the same diameter is also known (hereinafter referred to as “conventional example 4”). In the magnetron of the conventional example 4, the first vanes 31 are short-circuited by the strap ring 342 at the output-side end portion, and the second vanes 32 are short-circuited by the strap ring 341 at the input-side end portion. In this structure, since the capacitance between the strap rings 341 and 342 cannot be expected, the cross-sectional areas of the strap rings 341 and 342 need to be greatly increased. Therefore, it is difficult to reduce the material cost as a result. In addition, the above-described frequency adjustment becomes difficult.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to manufacture a magnetron having excellent characteristics at a low cost.

  In order to achieve the above object, a magnetron according to the present invention includes an anode cylinder extending along an axis, one first end in the axial direction, and the second end in the other axial direction. A plurality of first vanes and a plurality of second vanes which are formed in a plate shape, are radially arranged around the axis center, are joined to the inner peripheral surface of the anode cylinder, and are alternately arranged around the axis; An annular first strap ring that is disposed on the first end side of the vane and short-circuits the plurality of first vanes, and is disposed on the second end side of the vane. An annular second strap ring in which the first vanes are short-circuited; and an annular third strap ring that is disposed on the second end side of the vane and short-circuits the plurality of second vanes; An unbonded to any one of the plurality of first vanes Characterized by comprising a Na.

  In order to achieve the above object, a microwave oven according to the present invention includes an anode cylinder extending along an axis, one first end in the axial direction, and the second end in the other axial direction. A plurality of first vanes and a plurality of second vanes which are formed in a plate shape and are arranged radially on the axis center and joined to the inner peripheral surface of the anode cylinder and alternately arranged around the axis. And an annular first strap ring that is disposed on the first end side of the vane and short-circuits the plurality of first vanes, and is disposed on the second end side of the vane. An annular second strap ring in which the first vanes are short-circuited, and an annular third strap ring that is disposed on the second end side of the vane and short-circuits the plurality of second vanes. , The antenna joined to any one of the plurality of first vanes Characterized by comprising a magnetron with and.

  According to the present invention, a magnetron having excellent characteristics can be manufactured at a low cost.

1 is a schematic longitudinal sectional view of a magnetron according to a first embodiment of the present invention. It is a schematic longitudinal cross-sectional view of the anode structure of Example 1 of the magnetron based on the 1st Embodiment of this invention. It is a schematic longitudinal cross-sectional view of the anode structure of Example 2 of the magnetron based on the 1st Embodiment of this invention. It is a schematic longitudinal cross-sectional view of the anode structure of the comparative example 1 for demonstrating the magnetron which concerns on the 1st Embodiment of this invention. It is a schematic longitudinal cross-sectional view of the anode structure of the comparative example 2 for demonstrating the magnetron which concerns on the 1st Embodiment of this invention. It is a table | surface for demonstrating the magnetron which concerns on the 1st Embodiment of this invention, Comprising: It is the table | surface which showed the dimension of the magnetron of Example 1, 2 and Comparative Example 1,2. It is a table | surface for demonstrating the magnetron which concerns on the 1st Embodiment of this invention, Comprising: It is the table | surface which showed the characteristic of the magnetron of Example 1, 2 and Comparative Example 1,2. It is the figure which showed typically a mode that three strap rings of the magnetron based on the 1st Embodiment of this invention were punched out from a copper plate. It is a schematic longitudinal cross-sectional view of the anode structure of Example 3 of the magnetron based on the 2nd Embodiment of this invention. It is a schematic longitudinal cross-sectional view of the anode structure of Example 4 of the magnetron based on the 2nd Embodiment of this invention. It is a schematic longitudinal cross-sectional view of the anode structure of the magnetron of the prior art example 1. It is the figure which showed typically a mode that the four strap rings of the magnetron of the prior art example 1 were punched out from a copper plate. 6 is a schematic longitudinal sectional view of an anode structure of a magnetron of Conventional Example 2. FIG. It is a schematic longitudinal cross-sectional view of the anode structure of the magnetron of the prior art example 4.

[First Embodiment]
A magnetron and a microwave oven according to a first embodiment of the present invention will be described.

  First, the outline of the structure of the magnetron according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic longitudinal sectional view of a magnetron.

  The anode structure 10 includes an anode cylinder 20, an even number of vanes 30, and three strap rings 40. The anode cylinder 20 is made of copper, for example, and is formed in a cylindrical shape.

  Each vane 30 is made of copper, for example, and is formed in a plate shape. The even number of vanes 30 are arranged radially at the center of the axis 22 of the anode cylinder 20. The outer end of the vane 30 is joined to the inner peripheral surface of the anode cylinder 20. The inner end of the vane 30 is a free end. A cylindrical space surrounded by the free ends of the even number of vanes 30 is an electron action space.

  The three strap rings 40 are disposed at both ends of the even number of vanes 30 in the direction of the axis 22. Each strap ring 40 short-circuits a plurality of vanes 30 alternately arranged around the shaft 22 among the even number of vanes 30.

  The cathode 50 is a spiral filament and extends along the direction of the axis 22. The cathode 50 is provided in the above-described electron action space. The cathode 50 is arranged at an interval from the free ends of the even number of vanes 30. The anode structure 10 and the cathode 50 serve as a magnetron resonance part.

  The ring-shaped end hat 60 is fixed to the input side end of the cathode 50 (the lower end of FIG. 1). Further, the disk-shaped end hat 62 is fixed to the output side end portion (the upper end portion in FIG. 1) of the cathode 50.

  The side support rod 64 is electrically connected to the cathode 50 via a ring-shaped end hat 60. The center support rod 66 penetrates the center of the spiral filament of the cathode 50. The center support rod 66 is electrically connected to the cathode 50 via a disk-shaped end hat 62. The side support rod 64 and the center support rod 66 support the cathode 50 and supply current to the cathode 50.

  The pair of pole pieces 70 and 72 are each formed in a funnel shape. The pair of pole pieces 70 and 72 are joined to the input side end portion and the output side end portion of the anode cylinder 20, respectively.

  The pair of metal sealing bodies 74 and 76 are each formed in a cylindrical shape. The pair of metal sealing bodies 74 and 76 extend along the shaft 22. One end of the metal seal 74 is fixed to the input-side end of the anode cylinder 20 and the pole piece 70. On the other hand, one end of the metal sealing body 76 is fixed to the output side end portion of the anode cylinder 20 and the pole piece 72.

  The insulating cylinder 80 is made of ceramic and extends along the shaft 22. One end of the insulating cylinder 80 is joined to the output side end of the metal sealing body 76. The other end of the insulating cylinder 80 is joined to the exhaust pipe 82.

  The antenna 84 extends from one of the even number of vanes 30 through the output-side pole piece 72, extends inside the metal sealing body 76 and the insulating cylinder 80, and is led to the exhaust pipe 82. The antenna 84 serves to take out the oscillated microwave to the outside of the magnetron. The tip of the antenna 84 is sandwiched by the exhaust pipe 82. The cap 86 is provided so as to cover the outside of the exhaust pipe 82.

  The insulating stem 88 is joined to the end of the metal sealing body 74 on the input side.

  The pair of magnets 90 and 92 are each formed in a ring shape. The pair of magnets 90 and 92 are disposed outside the metal sealing bodies 74 and 76, respectively. The pair of magnets 90 and 92 are arranged so as to sandwich the anode cylinder 20 and generate a magnetic field in the direction of the axis 22. The yoke 94 is provided so as to surround the anode cylinder 20 and the magnets 90 and 92. The pair of magnets 90 and 92 and the yoke 94 form a magnetic circuit. The radiator 96 is provided between the anode cylinder 20 and the yoke 94, and releases heat generated by the oscillation to the outside of the magnetron.

  Next, characteristic portions of the magnetron according to the present embodiment will be described in detail using Examples 1 and 2 and Comparative Examples 1 and 2.

  First, the structure of Example 1 of the magnetron according to the present embodiment will be described with reference to FIG. FIG. 2 is a schematic longitudinal sectional view of the anode structure of Example 1.

  The magnetron of Example 1 has ten vanes 30. The ten vanes 30 are radially arranged around the shaft 22 in the anode cylinder 20. The ten vanes 30 are classified into five first vanes 31 and five second vanes 32. The first vane 31 and the second vane 32 are alternately arranged around the axis 22. The antenna 84 is connected to one output-side end (the upper end in FIG. 2, hereinafter referred to as “second end”) of the first vane 31.

  The input end of the first vane 31 (the lower end of FIG. 2; hereinafter referred to as “first end”) and the output end (hereinafter referred to as “second end”). ) Are formed with notches 31a and 31b having different shapes. Similarly, notches 32a and 32b having different shapes are formed at the first end and the second end of the second vane 32, respectively.

  The magnetron according to the first embodiment includes three strap rings (first to third strap rings) 41 to 43. The three strap rings 41 to 43 are made of copper and formed in an annular shape. The three strap rings 41 to 43 are arranged at the center of the shaft 22.

  In the present embodiment, the diameters of the three strap rings 41 to 43 are different from each other. The three strap rings 41 to 43 are designed to be smaller in the order of the second strap ring 42, the first strap ring 41, and the third strap ring 43.

  In the present embodiment, the three strap rings 41 to 43 are obtained by punching one copper plate 48 four times by pressing as shown in FIG. Therefore, the inner diameter of the second strap ring 42 is equal to the outer diameter of the first strap ring 41. Further, the inner diameter of the first strap ring 41 is equal to the outer diameter of the third strap ring 43.

  When punching, a slight taper may be formed on the shearing surfaces of the strap rings 41 to 43. Further, when punching, the copper plate 48 is fixed by applying pressure so that the copper plate 48 is not distorted. Therefore, the inner diameter of the second strap ring 42 and the outer diameter of the first strap ring 41, and the inner diameter of the first strap ring 41 and the outer diameter of the third strap ring 43 are substantially equal, but may not completely match. is there.

  The first strap ring 41 is disposed on the first end side (input side) of the vane 30. The first strap ring 41 is inserted through the notches 31 a of the five first vanes 31 and the notches 32 a of the five second vanes 32. The first strap ring 41 is joined to the inner edge of the notch 31a of the first vane 31 by brazing, but does not contact the inner edge of the notch 32a of the second vane 32. That is, the first strap ring 41 short-circuits the five first vanes 31.

  The second strap ring 42 is disposed on the second end side (output side) of the vane 30. The second strap ring 42 is inserted through the notches 31 b of the five first vanes 31 and the notches 32 b of the five second vanes 32. The second strap ring 42 is joined to the inner edge of the notch 31b of the first vane 31 by brazing, but does not contact the inner edge of the notch 32b of the second vane 32. That is, the second strap ring 42 short-circuits the five first vanes 31.

  The third strap ring 43 is disposed on the second end side (output side) of the vane 30. The third strap ring 43 is inserted through the notches 31 b of the five first vanes 31 and the notches 32 b of the five second vanes 32. The third strap ring 43 is joined to the inner edge of the notch 32 b of the second vane 32 by brazing, but does not contact the inner edge of the notch 31 b of the first vane 31. That is, the third strap ring 43 short-circuits the five second vanes 32.

  As described above, in the first embodiment, the first strap ring 41 is disposed on the first end side (input side) of the vane 30, and the second and third strap rings 42 and 43 are the second end of the vane 30. It is arranged on the part side (output side). The first and second strap rings 41 and 42 short-circuit the first vanes 31 to which the antenna 84 is connected, and the third strap ring 43 short-circuits the second vanes 32.

  That is, the first vanes 31 including the vane to which the antenna 84 is connected are short-circuited by the first strap ring 41 at the first end and short-circuited by the second strap ring 42 at the second end. The second vanes 32 are short-circuited by the third strap ring 43 at the second end.

  When the magnetron oscillates, the five first vanes 31 have the same potential due to the first strap ring 41 and the second strap ring 42. Further, the five second vanes 32 have the same potential due to the third strap ring 43.

  Next, the structure of Example 2 of the magnetron according to this embodiment will be described with reference to FIG. FIG. 3 is a schematic longitudinal sectional view of the anode structure according to the second embodiment. In addition, the same code | symbol is attached | subjected to the same part as Example 1, or a similar part, and duplication description is abbreviate | omitted.

  In the second embodiment, similarly to the first embodiment, the first strap ring 41 is disposed on the first end side (input side) of the vane 30, and the second and third strap rings 42 and 43 are disposed on the vane 30. It arrange | positions at the 2nd edge part side (output side). The first strap ring 41 short-circuits the first vanes 31 including the vane to which the antenna 84 is connected.

  On the other hand, in the second embodiment, unlike the first embodiment, the second strap ring 42 short-circuits the second vanes 32. The third strap ring 43 short-circuits the first vanes 31 including the vane to which the antenna 84 is connected.

  In addition, the 1st thru | or 3rd strap rings 41-43 of Example 1 and the 1st thru | or 3rd strap rings 41-43 of Example 2 are each designed by the same diameter. In the first embodiment and the second embodiment, the vane 30 to be short-circuited is changed by changing the shapes of the notches 31b and 32b on the second end side.

  Next, the structures of Comparative Examples 1 and 2 will be described with reference to FIGS. FIG. 4 is a schematic longitudinal sectional view of the anode structure of Comparative Example 1. FIG. 5 is a schematic longitudinal sectional view of the anode structure of Comparative Example 2. In addition, the same code | symbol is attached | subjected to the same part as Example 1, 2 or a similar part, and duplication description is abbreviate | omitted.

  In Comparative Examples 1 and 2, as in Examples 1 and 2, the first strap ring 41 is disposed on the first end side (input side) of the vane 30, and the second and third strap rings 42 and 43 are The vane 30 is disposed on the second end side (output side).

  On the other hand, in the first and second comparative examples, unlike the first and second embodiments, the first strap ring 41 short-circuits the second vanes 32 to which the antenna 84 is not connected.

  In the first comparative example, as in the first embodiment, the second strap ring 42 short-circuits the first vanes 31 and the third strap ring 43 short-circuits the second vanes 32.

  In Comparative Example 2, as in Example 2, the second strap ring 42 short-circuits the second vanes 32 and the third strap ring 43 short-circuits the first vanes 31.

  In addition, the 1st thru | or 3rd strap rings 41-43 of Example 1, 2 and the 1st thru | or 3rd strap rings 41-43 of the comparative examples 1 and 2 are each designed by the same diameter. In Examples 1 and 2 and Comparative Examples 1 and 2, the shapes of the notches 31a, 31b, 32a, and 32b are different depending on the vane 30 that is short-circuited.

  Further, the magnetrons of Examples 1 and 2 and Comparative Examples 1 and 2 are all designed to have the same shape and size except for the notches 31a, 31b, 32a, and 32b. In particular, FIG. 6 shows the dimensions of a portion having a great influence on the characteristics of the magnetron described later.

  Next, the characteristics of the magnetrons of Examples 1 and 2 and Comparative Examples 1 and 2 are compared using FIG. FIG. 7 is a table showing the characteristics of the magnetrons of Examples 1 and 2 and Comparative Examples 1 and 2.

  FIG. 7 shows the minimum value of back heat (cathode reverse impact) of the magnetrons of Examples 1 and 2 and Comparative Examples 1 and 2, the difference between the maximum value and the minimum value of back heat, and the measured values of load stability. Show. In general, from the viewpoints of magnetron operational stability, equipment matching, and product lifetime, it is desirable that the back heat minimum value and load stability be large, and the maximum and minimum back heat values. About the difference with a value, it is desirable that the value is small.

  As can be seen from FIG. 7, the characteristics are excellent in the order of Example 1, Example 2, Comparative Example 1, and Comparative Example 2. The magnetrons of Examples 1 and 2 have sufficient characteristics that can be applied to a microwave oven, but the magnetrons of Comparative Examples 1 and 2 do not have sufficient characteristics that can be applied to a microwave oven. .

  As described above, in the first and second embodiments, the first vane 31 to which the antenna 84 is connected is short-circuited by the strap ring 40 at the first end and the second end. Therefore, in the first and second embodiments, the balance between the input-side potential and the output-side potential of the first vane 31 from which the microwave is derived is good, and both are stable.

  On the other hand, as described above, in Comparative Examples 1 and 2, the first vane 31 to which the antenna 84 is connected is short-circuited by the strap ring 40 at the second end, but short-circuited by the strap ring 40 at the first end. It has not been. Therefore, in Comparative Examples 1 and 2, the balance between the input-side potential and the output-side potential of the first vane 31 from which the microwave is derived is poor, and the stability is low.

  Whether or not the first vane 31 to which the antenna 84 is connected is short-circuited by the strap ring 40 at both ends in the direction of the axis 22 is considered due to the difference in characteristics between the first and second embodiments and the first and second comparative examples. It is done.

  From comparison between the first embodiment and the second embodiment, it can be seen that it is preferable that the second strap ring 42 having a large diameter is joined to the first vane 31 to which the antenna 84 is connected.

  Hereinafter, the effect of the magnetron according to the present embodiment (magnetron of Examples 1 and 2) will be described.

  As described above, in the magnetron according to this embodiment, the strap ring 40 is joined to both sides (input side and output side) of the first vane 31 in the direction of the axis 22 to which the antenna 84 is connected. Therefore, the potential on the input side and the potential on the output side of the first vane 31 from which the microwave is derived are both stable and have excellent characteristics.

  According to the present embodiment, the three strap rings 41 to 43 can provide excellent characteristics equivalent to those of the conventional magnetron including the four strap rings 141 to 144. Therefore, compared with the magnetron of the prior art example 1, material cost is reduced and productivity is improved. As a result, a magnetron having excellent characteristics can be manufactured at low cost.

  In this embodiment, since the diameters of the three strap rings 41 to 43 are different from each other, the three strap rings 41 to 43 can be obtained from one copper plate. Therefore, the material utilization efficiency is high, and the material cost can be further reduced. In addition, in the present embodiment, the inner diameter of the second strap ring 42 and the outer diameter of the first strap ring 41 are equal, and the inner diameter of the first strap ring 41 and the outer diameter of the third strap ring 43 are equal. Therefore, three strap rings 41 to 43 can be obtained by punching four times from one copper plate 48. Therefore, productivity is improved.

  Further, a first strap ring 41 is disposed on the first end side (input side) of the vane 30. Therefore, it is possible to easily adjust the resonance frequency, which is performed by deforming the first strap ring 41 after assembly.

[Second Embodiment]
A magnetron (magnetron of Examples 3 and 4) and a microwave oven according to a second embodiment of the present invention will be described with reference to FIGS. 9 and 10. FIG. 9 is a schematic longitudinal sectional view of the anode structure of Example 3. FIG. 10 is a schematic longitudinal sectional view of the anode structure of Example 4. In addition, since this embodiment is a modification of 1st Embodiment, the same code | symbol is attached | subjected to the same part or similar part as 1st Embodiment, and duplication description is abbreviate | omitted.

  In the first embodiment (Examples 1 and 2), the first strap ring 41 is disposed on the first end side (input side) of the vane 30, and the second and third strap rings 42 and 43 are formed on the vane. 30 is arranged on the second end side (output side).

  On the other hand, in the present embodiment, the first strap ring 41 is arranged on the second end side (output side) of the vane 30, and the second and third strap rings 42 and 43 are on the first end side of the vane 30. (Input side).

  In the third embodiment, similarly to the first embodiment, the first and second strap rings 41 and 42 short-circuit the first vanes 31 including the vane to which the antenna 84 is connected, and the third strap ring 43 includes the first strap ring 43. The two vanes 32 are short-circuited.

  In the fourth embodiment, similarly to the second embodiment, the first and third strap rings 41 and 43 short-circuit the first vanes 31 including the vane to which the antenna 84 is connected, and the second strap ring 42 is The second vanes 32 are short-circuited.

  Also in this embodiment, as in the first embodiment, the first vane 31 to which the antenna 84 is connected is short-circuited by the strap ring 40 at the first end and the second end. Therefore, an effect equivalent to that of the first embodiment can be obtained.

[Other Embodiments]
The above embodiments are merely examples, and the present invention is not limited to these. For example, in the above embodiment, the first to third strap rings 41 to 43 are designed to have different diameters. For example, the first strap ring 41 and the second strap ring 42 have the same diameter, The three strap rings 43 may be designed to have a smaller diameter than the first and second strap rings 41 and 42. In this case, the scrap 46 at the time of punching from the copper plate 48 is increased, but the amount of material used is almost the same, so that the cost can be reduced by recycling.

  Further, the outer diameter of the first strap ring 41 may be designed to be smaller than the inner diameter of the second strap ring 42, and the outer diameter of the third strap ring 43 may be designed to be smaller than the inner diameter of the first strap ring 41.

DESCRIPTION OF SYMBOLS 10 ... Anode structure, 20 ... Anode cylinder, 22 ... Shaft of anode cylinder, 30 ... Vane, 31 ... 1st vane, 32 ... 2nd vane, 40 ... Strap ring, 41 ... 1st strap ring, 42 ... 2nd strap Ring, 43 ... Third strap ring, 46 ... Scrap, 48 ... Copper plate, 50 ... Cathode, 60, 62 ... End hat, 64 ... Side support rod, 66 ... Center support rod, 70, 72 ... Pole piece, 74, 76 ... Metal sealing body, 80 ... insulating cylinder, 82 ... exhaust pipe, 84 ... antenna, 86 ... cap, 88 ... insulating stem, 90, 92 ... magnet, 94 ... yoke, 96 ... radiator

Claims (5)

An anode cylinder extending along the axis;
It is formed in a plate shape having one first end portion in the axial direction and the other second end portion in the axial direction, and is arranged radially at the axial center and joined to the inner peripheral surface of the anode cylinder. A plurality of first vanes and a plurality of second vanes arranged alternately around the axis;
An annular first strap ring that is disposed on the first end side of the vane and short-circuits the plurality of first vanes;
An annular second strap ring that is disposed on the second end side of the vane and short-circuits the plurality of first vanes;
An annular third strap ring disposed on the second end side of the vane and short-circuiting the plurality of second vanes;
An antenna joined to any one of the plurality of first vanes;
A magnetron comprising:   The magnetron according to claim 1, wherein an outer diameter of the third strap ring is equal to or smaller than an inner diameter of the second strap ring.   The outer diameter of the first strap ring is less than or equal to the inner diameter of the second strap ring, and the outer diameter of the third strap ring is less than or equal to the inner diameter of the first strap ring. 2. The magnetron according to 2.   The outer diameter of the first strap ring and the inner diameter of the second strap ring are equal, and the outer diameter of the third strap ring and the inner diameter of the first strap ring are equal. 3. The magnetron according to 3. An anode cylinder extending along the axis;
It is formed in a plate shape having one first end portion in the axial direction and the other second end portion in the axial direction, and is arranged radially at the axial center and joined to the inner peripheral surface of the anode cylinder. A plurality of first vanes and a plurality of second vanes arranged alternately around the axis;
An annular first strap ring that is disposed on the first end side of the vane and short-circuits the plurality of first vanes;
An annular second strap ring that is disposed on the second end side of the vane and short-circuits the plurality of first vanes;
An annular third strap ring disposed on the second end side of the vane and short-circuiting the plurality of second vanes;
An antenna joined to any one of the plurality of first vanes;
A microwave oven provided with a magnetron equipped with

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