CN100583369C - Magnetron - Google Patents

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Publication number
CN100583369C
CN100583369C CN200710006187A CN200710006187A CN100583369C CN 100583369 C CN100583369 C CN 100583369C CN 200710006187 A CN200710006187 A CN 200710006187A CN 200710006187 A CN200710006187 A CN 200710006187A CN 100583369 C CN100583369 C CN 100583369C
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harmonic components
canister
higher harmonic
high frequency
choke groove
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CN101013646A (en
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东正寿
川口敏夫
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Toshiba Hokuto Electronics Corp
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Toshiba Hokuto Electronics Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/14—Leading-in arrangements; Seals therefor
    • H01J23/15—Means for preventing wave energy leakage structurally associated with tube leading-in arrangements, e.g. filters, chokes, attenuating devices
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/72—Radiators or antennas
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/36—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy
    • H01J23/40—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy to or from the interaction circuit
    • H01J23/44—Rod-type coupling devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/36—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy
    • H01J23/54—Filtering devices preventing unwanted frequencies or modes to be coupled to, or out of, the interaction circuit; Prevention of high frequency leakage in the environment
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/74—Mode transformers or mode stirrers

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microwave Tubes (AREA)

Abstract

To provide a magnetron having a lambada /4 type choke structure suppressing higher harmonic wave components propagated in a higher order mode or suppressing an unnecessary radiation of the medium band interposed between two higher harmonic waves having frequencies of integer multiples of the fundamental wave. The magnetron comprising a high frequency wave generating part 11 generating a high frequency wave, an antenna 24 extracting the high frequency wave, a cylindrical metallic envelope 18 surrounding the antenna 24 and a lambada /4 type choke structure C2 suppressing a higher harmonic wave component propagated in a fundamental mode in the metallic envelope 18, another lambada /4 type choke structure C1 suppressing a higher harmonic wave component propagated in a higher order mode in the metallic envelope has been provided.

Description

Magnetron
Technical field
The present invention relates to a kind of magnetron that is used in microwave heating equipment etc.
Background technology
The magnetron of output high frequency waves, the magnetron that the microwave oven that for example is used for the culinary art of food and thaws etc. is used, by the high frequency waves generating unit that generates high frequency waves, to the outside take out high frequency waves antenna, and the canister etc. of tubular that surrounds antenna and form the part of vacuum tank constitute.
Magnetron for microwave oven produces has for example microwave of the frequency of 2450MHz bandwidth.At this moment, fundametal compoment and higher harmonic components produce simultaneously.If higher harmonic components is emitted to the outside, then higher harmonic components is admitted in the heating space of microwave oven etc. with fundametal compoment.Because the higher harmonic components wavelength is short, shielding is difficulty, so to external leakage, cause problems such as air interference sometimes.Therefore, with legal provisions the limiting value of leaking.
The magnetron for microwave oven in past in order to suppress higher harmonic components, has for example disposed λ/4 type choking structures (with reference to patent documentation 1～3) at efferent.λ/4 type choking structures for example are provided with short circuit on one side and the so-called choke groove of another side open circuit.
Here, about magnetron in the past, be example with the magnetron for microwave oven, the sectional view of Fig. 2 of a part illustrates with reference to extracting out wherein.
The high frequency waves generating unit 31 that produces high frequency waves is made of anode cylinder 32 grades, is fixing funnelform pole piece 33 respectively in the upper and lower opening part of anode cylinder 32.Owing to the relation on the drawing, only expression illustrates the pole piece 33 of top among Fig. 2.Center at anode cylinder 32 for example disposes spiral helicine negative electrode 34 on the tubular axis m.The two ends of negative electrode 34 are fixed on the end cap (end hat) 35.Owing to the relation on the drawing, only represent the end cap 35 of the upper end of fixed negative pole 34 among Fig. 2.
34 are provided with a plurality of blades (vane) radially from anode cylinder 32 towards negative electrode.The interval that a plurality of blades 36 are separated by certain on the circumferencial direction of anode cylinder 32 is provided with.One end of blade 36 engages with the inner surface of anode cylinder 32, and the other end extends near the negative electrode 34, becomes free end.Connecting ring 37a, the 37b (strap ring) that utilize the different a pair of size of diameter are every an extremely following part of top part that connects each blade 36.Owing to the relation on the drawing, only expression connects connecting ring 37a, the 37b of the top part of blade 36 among Fig. 2.
The canister 38 of tubular is fixed on the outlet side of pole piece 33.The lower end of canister 38, for example the front end of the 1st flange portion 38a of the ring-type of broadening engages with the upper end of anode cylinder 32 laterally.
The 1st cylindrical body 39 is set in the inboard of canister 38.The 1st cylindrical body 39 and canister 38 form the choke groove of ring-types, for example constitute the 1st λ/4 type choking structure C1 that suppress 5 order harmonic components.
Tubular pottery 40 engages with the upper end 38b of canister 38, and blast pipe 41 engages with the upper end of tubular pottery 40.Whole blast pipe 41 is covered by cover 42 (cap).
Blast pipe 41 is made of for example dual cylindrical portion 41a and sealing 41b etc.Dual cylindrical portion 41a constitutes for example the 2nd λ of 4 order harmonic components/4 type choking structure C2 of inhibition.Sealing 41b constitutes for example the 3rd λ of 3 order harmonic components/4 type choking structure C3 of inhibition.
The antenna 43 of the high frequency waves that taking-up generates by high frequency waves generating unit 31 is set in the inboard of canister 38 and tubular pottery 40, blast pipe 41.One end of antenna 43 is connected with a blade 36, and the other end passes the opening 33a of pole piece 33, and extends to the inboard of canister 38, is deflated pipe 41 and clamps and fix.
In said structure, the high frequency waves that generated by high frequency waves generating unit 31 are fetched into the outside by antenna 43.At this moment, with the higher harmonic components that fundametal compoment generates simultaneously, for example 3 order harmonic components (7.35GHz)～5 order harmonic components (12.25GHz) suppress by the 1st～the 3rd λ/4 type choking structures.
No. 961611 communique of [patent documentation 1] special permission
No. 2128827 communique of [patent documentation 2] special permission
[patent documentation 3] spy opens clear 63-264848 communique
The magnetron in past is magnetron for microwave oven for example, at efferent a plurality of λ/4 type choking structures is set and suppresses higher harmonic components.λ/4 type choking structures have the coaxial dual cylindrical structure of for example being made up of inside cylindrical and outside cylindrical, between inside cylindrical and outside cylindrical etc., form the so-called choke groove of a terminal shortcircuit and other end open circuit.The length of choke groove, for example the size on the tube axial direction of choke groove generally be set at inhibition higher harmonic components wavelength about 1/4.
The electric field of λ/4 type choking structures concentrates on the open end of choke groove, and produces capacitive component.Therefore can know that if frequency raises, then the influence of parasitic capacitance will increase, can be with the effect of the high order harmonic component that is inhibited than the littler size of theoretic 1/4 wavelength.
On experience, also know in addition, if the inside dimension of choke groove, promptly from the open end of a side of choke groove along its inner surface to being positioned at the half-wavelength that approaches this higher harmonic components with the measured length (creepage distance of choke groove) of the open end of the opposite side of its reverse side, the effect that then suppresses high order harmonic component can increase.
For example, 1/4 wavelength of 5 order harmonic components (12.25GHz) is about 6.12mm.But because the empirical rule of the inside dimension of the influence of parasitic capacitance and relevant choke groove, the length of actual choke groove probably is about 5mm, for example is 4～6mm.
Yet, if the internal diameter of λ/4 type choking structures reduces, shortening with the distance meeting of antenna, the effect that suppresses high order harmonic component increases.But, if internal diameter diminishes, manufacturing property variation then.In addition, place such as between the cylindrical body of antenna and choking structure member, the possibility that the multipactor discharge takes place improves.Strengthen with the degree of coupling of antenna, the influence of the impedance of the firing equipment of microwave oven etc. and power supply, load-up condition etc. will increase, and exist the zone of oscillatory instability to become big problem.
In addition, the λ that uses in the magnetron for microwave oven in past/4 type choking structures, be hypothesis utilize with antenna as inner wire, with canister as the fundamental mode of the coaxial line of outer conductor, be the propagation of so-called TEM pattern.The size of choke groove is a benchmark with 1/4 wavelength of free space wavelength also.But,, can utilize the propagation of the higher modes of higher harmonic components according to the diameter of inner wire that works as coaxial line and outer conductor.
For example, be a if establish the radius of a circle that the outer circumference surface of inner wire when blocking the inner wire that constitutes coaxial line forms (inner wire overall diameter 1/2), the radius of a circle that the inner peripheral surface of outer conductor forms when blocking outer conductor (outer conductor interior diameter 1/2) is b, TEn 1The cut-off wavelength of pattern is λ c, and the relation of formula (1) is then arranged:
λc＝π(a+b)/n …(1)
As seen from formula (1), under the situation of TE11 pattern,, then can carry out the propagation of higher modes if the value of π (a+b) is bigger than λ c.For example, when the overall diameter of inner wire is 2.5mm, if the interior diameter of outer conductor more than 13.08mm, then 5 order harmonic components can enough higher modes (TE11 pattern) propagate.Therefore, in order to prevent the manufacturing property variation, perhaps,, then can carry out the propagation of TE11 pattern if increase the interior diameter of λ/4 type choking structures in order to make vibrational stabilization.
If can propagate for example TE11 pattern of higher modes, then this high order harmonic component is mainly selected the less side in the load impedance of the load impedance of TEM pattern and TE11 pattern, a side who promptly propagates easily.
The λ in past/4 type choking structures are the size that benchmark decides choke groove with 1/4 wavelength of free space wavelength.In addition, even identical higher harmonic components is also inequality with the wavelength in pipe of first-harmonic pattern and higher modes.Therefore, the λ that uses in the magnetron for microwave oven in past/4 type choking structures promptly allow to suppress the higher harmonic components propagated with fundamental mode, but owing to use the wavelength difference of higher modes, so suppress also insufficiently, this higher harmonic components will be leaked.
In addition, the λ in past/4 type choking structures are to set size etc. like this, make to suppress to have the N order harmonic components (back is called common higher harmonic components) of frequency of the integral multiple of first-harmonic.In fact, be clipped in frequency band between each frequencies of 3 order harmonic components and 4 order harmonic components etc., also can be clipped in higher harmonic components between the frequency band of 2 adjacent common higher harmonic components (back is called the higher harmonic components of intermediate frequency band).What for example be positioned at 3.5 order harmonic components of approximate center of intermediate frequency band and 4.5 order harmonic components etc. does not need radial component, reaches the energy level identical or higher with common higher harmonic components sometimes.
The λ in past/4 type choking structures can not suppress the higher harmonic components of intermediate frequency band fully, exist the problem of the higher harmonic components leakage of intermediate frequency band.In addition, in order to suppress the higher harmonic components of intermediate frequency band, if λ/4 type choking structures that intermediate frequency band is used are set specially, the problem that then exists cost to improve or maximize.
The invention provides a kind of magnetron, purpose is to solve above-mentioned shortcoming, has higher harmonic components that inhibition propagates with higher modes or the λ/4 type choking structures that suppress the higher harmonic components of intermediate frequency band.
Summary of the invention
Magnetron of the present invention has: generate high frequency waves the high frequency waves generating unit, take out above-mentioned high frequency waves antenna, surround this antenna the tubular canister, suppress the λ/4 type choking structures of the higher harmonic components in above-mentioned canister, propagated with fundamental mode, in such magnetron, characteristics are to be provided with: the 2nd λ/4 type choking structures that suppress the above-mentioned higher harmonic components propagated with higher modes in above-mentioned canister.
In addition, magnetron of the present invention has: the high frequency waves generating unit that generates high frequency waves, take out the antenna of above-mentioned high frequency waves, surround the tubular canister of this antenna, in this canister, form the cylindrical body of the choke groove of λ/4 type choking structures, in such magnetron, characteristics are: according to the 1st higher harmonic components that suppresses to propagate in above-mentioned canister with fundamental mode, and the 2nd higher harmonic components different with above-mentioned the 1st higher harmonic components frequency and that in above-mentioned canister, propagate with higher modes the two, thereby set the size of the length of above-mentioned choke groove.
If employing the present invention then is provided with the λ/4 type choking structures of inhibition with the higher harmonic components of fundamental mode propagation, the λ/4 type choking structures of the propagation of the usefulness higher modes that suppress identical higher harmonic components are set simultaneously.Therefore, even under the situation of a higher harmonic components enough fundamental mode of energy and both propagation of higher modes, also can positively suppress, can prevent the leakage of higher harmonic components.
In addition, by the 1st higher harmonic components that suppresses simultaneously with a λ/4 type choking structures to propagate and and 2nd higher harmonic components that with higher modes propagate different with its frequency with fundamental mode.Therefore, can suppress a plurality of higher harmonic components of different communication modes by enough common λ/4 type choking structures, not make cost improve and can prevent the leakage of higher harmonic components.
Description of drawings
Fig. 1 is the fragmentary cross sectional view of explanation example of the present invention.
Fig. 2 is the explanation fragmentary cross sectional view of example in the past.
Label declaration
11 high frequency waves generating units
12 anode cylinders
13 pole pieces
14 negative electrodes
15 end caps
16 blades
17a, 17b connecting ring
18 canisters
19 the 1st cylindrical body
20 the 2nd cylindrical body
21 tubular potteries
22 blast pipes
23 covers
24 antennas
The λ of C1～C4 the 1st～4th/4 type choking structures
The m tubular axis
Embodiment
About example of the present invention, be example with the magnetron for microwave oven, illustrate with reference to the sectional view of Fig. 1.
The high frequency waves generating unit 11 that generates high frequency waves is made of anode cylinder 12 grades.At the opening portion of anode cylinder 12, outlet side and the opening portion of input side below the diagram, the pole piece 13 of fixed funnel shape respectively above the diagram for example.Because the relation of drawing, Fig. 1 only represents the pole piece 13 of outlet side.The spiral helicine negative electrode 14 of configuration on the center of anode cylinder 12, for example tubular axis m.
The diagram of negative electrode 14 is fixed on the end cap 15 at two ends up and down.Because the relation of drawing, Fig. 1 only represents to be fixed on the upper end of negative electrode 14, the end cap 15 of for example outlet side.
Be to negative electrode 14 from anode cylinder 12 a plurality of blades 16 are set radially.Blade 16 for example is a rectangle, and separates certain interval be provided with on the circumferencial direction of anode cylinder 12.One end of blade 16 engages with the inner surface of anode cylinder 12, and the other end extends near the negative electrode 14 always, becomes free end.Top part and following connecting ring 17a, the 17b that is partly disposing the different a pair of size of diameter along blade 16.Each blade 16 is coupled together every one by connecting ring 17a or connecting ring 17b.Because the relation of drawing, Fig. 1 only represents to connect connecting ring 17a, the 17b of the top part of blade 16.
The canister 18 of tubular is fixed on the outlet side of pole piece 13.The 2nd flange portion 18c of the cylindrical portion 18b that canister 18 extends abreast by the 1st flange portion 18a of the ring-type that for example is positioned at diagram lower end and outside broadening, with tubular axis m, the ring-type of extending to the inside and constitute to the bend 18d of tubular axis m direction bending etc. from the 2nd flange portion 18c from the upper end of cylindrical portion 18b.The end edge of the 1st flange portion 18a engages with the upper end of anode cylinder 12.
The 1st cylindrical body 19 and the inboard of canister 18, the interior side engagement of for example cylindrical portion 18b.The 1st cylindrical body 19 for example has the cylindrical portion 19a that extends abreast with tubular axis m and the flange portion 19b of the ring-type of extending laterally perpendicular to tubular axis from the upper end of cylindrical portion 19a etc., and this cross section roughly is the word shape of falling L.The cylindrical portion 18b arranged coaxial of cylindrical portion 19a and canister 18, the annular end face of flange portion 19b engages with the inner surface of canister 18.
Canister 18 and the 1st cylindrical body 19 form the ring-type choke groove of a terminal shortcircuit of diagram top and the other end open circuit below the diagram, constitute the 1st λ/4 type choking structure C1.About the length on the tubular axis m direction of the choke groove that forms the 1st λ/4 type choking structure C1, the length of the cylindrical portion 19a of the 1st cylindrical body 19 and canister 18 subtends for example, as described later, be set at 4.5 times frequency suppressing to have first-harmonic and 4.5 order harmonic components of propagating with fundamental mode and 5 times frequency and the size of 5 order harmonic components propagated with higher modes with first-harmonic.
The 2nd cylindrical body 20 of ring-type and the inboard of canister 18, the illustrated lower surface engages of the 2nd flange portion 18c for example.The 2nd cylindrical body 20 is formed by cylindrical portion 20a and flange portion 20b etc.Though different with the size of the 1st cylindrical portion 19, shape is roughly the same, this cross section forms the roughly font of falling L.
Canister 18 is identical with the situation of the 2nd cylindrical body 20 and the 1st λ/4 type choking structure C1, forms the choke groove of ring-type, constitutes 5 overtones bands that suppress for example to have first-harmonic and the 2nd λ/4 type choking structure C2 of 5 order harmonic components propagated with fundamental mode.
Tubular pottery 21 engages with the upper end of canister 18, the front end of for example bend 18d.Blast pipe 22 engages with the upper end of tubular pottery 21, and whole blast pipe 22 is covered by cover 23.
Blast pipe 22 is made of for example dual cylindrical portion 22a and sealing 22b etc.Dual cylindrical portion 22a is made of inner cylindrical section a1 and outer cylinder portion a2 etc.Between inner cylindrical section a1 and outer cylinder portion a2, form the choke groove of ring-type, for example, constitute the 3rd λ/4 type choking structure C3 of 4 order harmonic components of 4 times the frequency that suppresses to have first-harmonic.Inner cylindrical section a1 and sealing 22b side within it form continuous space.
Sealing 22b for example its central authorities is outstanding upward, and the inner space of sealing 22b and inner cylindrical section a1 constitutes the 4th λ/4 type choking structure C4 of 3 order harmonic components of 3 times the frequency that suppresses to have first-harmonic.
In addition, in the inboard of canister 18 and tubular pottery 21, blast pipe 22 etc., the antenna 24 that takes out the high frequency waves that generate with high frequency waves generating unit 11 is set.One end of antenna 24 is connected with a blade 16, and the other end passes the opening 13a of pole piece 13, and extends to the inboard of canister 18, and the sealing 22b that is deflated pipe 22 clamps and fixes.
Here, λ/4 type choking structure C1, C2 about the above-mentioned the 1st and the 2nd is described.In the following description, the internal diameter φ that establishes the cylindrical portion 18b of canister 18 is 19mm, and the external diameter of antenna 24 is 2.5mm, and the internal diameter φ 2 of the cylindrical portion 20a of the 2nd cylindrical body 20 is 14mm, and thickness of slab is 0.3mm.
Then, the 1st λ/4 type choking structure C1 are set in the size on the tubular axis m direction of its choke groove, make it possible to suppress the TEM pattern of 4.5 subharmonic and the TE11 pattern of 5 subharmonic.For example the cylindrical portion 18b of canister 18 is parallel with the cylindrical portion 19a of the 1st cylindrical body 19 and the length of the part of subtend determines the external diameter φ 3 of the cylindrical portion 19a of the 1st cylindrical body 19, thereby makes and equate with 1/4 of the wavelength in pipe separately of the TE11 pattern of the TEM pattern of 4.5 subharmonic and 5 subharmonic.
Generally, wavelength in pipe (λ g) try to achieve by following formula (2).
[mathematical expression 3]
λ g = λ n / 1 - ( λ n λ c ) 2 - - - ( 2 )
If establish 4.5 subharmonic is 11GHz, and then the wavelength in pipe of this TEM pattern is 27.254mm.Therefore, use formula (1) and formula (2) are tried to achieve the external diameter φ 3 of the cylindrical portion 19a of the 1st cylindrical body 19, thereby make that the wavelength in pipe of TE11 pattern of 5 subharmonic is 27.254mm.
In formula (2), if substitution λ g=27.254mm, λ n(free space wavelengths of 5 subharmonic)=24.473mm then tries to achieve λ c=55.61mm.
Then, in formula (1) if in substitution λ c=55.61mm, then 55.61=π (a+b).Because b=19/2=9.5, so obtain a=8.2.
Here, a is the outer circumference surface radius of the cylindrical body 19 of choke groove part, promptly when the cylindrical portion 19a of the tubular axis m that will be parallel to the 1st cylindrical body 19 carries out the cross section, the radius of a circle that forms of the outer circumference surface of this cylindrical portion 19a, b is the inner peripheral surface radius of the cylindrical portion 18b of choke groove part, promptly when the cylindrical portion 18b of the tubular axis that will be parallel to canister 18 carries out the cross section, the radius of a circle that forms of the inner peripheral surface of this cylindrical portion 18b.
Therefore, the external diameter φ 3 of the cylindrical portion 19a of the 1st cylindrical body 19 is 16.4mm (8.2 * 2), is 0.3mm if establish thickness of slab, and then internal diameter φ 4 is 15.8mm.
If the diameter of the cylindrical portion 19a of the cylindrical portion 18b of canister 18 and the 1st cylindrical body 19 is set at above-mentioned size, then the wavelength in pipe of the TE11 pattern of the TEM pattern of 4.5 subharmonic and 5 subharmonic becomes identical.Therefore, can suppress the TEM pattern of 4.5 subharmonic and the TE11 pattern of 5 subharmonic by the 1st λ/4 type choking structure C1.
4.5 1/4 wavelength of subharmonic is 6.813mm (27.254/4mm).But, be half-wavelength (13.626mm) if make the inside dimension (creepage distance) of choke groove, then the length on the tube axial direction of Shi Ji choke groove is about about 6.2mm.
Size on the tubular axis m direction of the cylindrical portion 20a of the 2nd cylindrical body 20 is set at fundamental mode (TEM pattern) wavelength in pipe 1/4, make the 2nd cylindrical body 20 suppress the TEM pattern of 5 subharmonic.The wavelength in pipe of fundamental mode equals free space wavelength, and 1/4 wavelength is 6.12mm.In this case, if make the size (creepage distance) of choke groove also be the 12.24mm of half-wavelength, then the length of Shi Ji choke groove is about 5mm.
The situation of above-mentioned example explanation is to use the 1st and the 2nd λ/4 type choking structures, 5 order harmonic components that inhibition is propagated with fundamental mode and higher modes.But,, then also can suppress other higher harmonic components of propagating with fundamental mode and higher modes if suitably set the size of λ/4 type choking structures.
In addition, be to form canister and cylindrical body respectively, again both are engaged.But, also canister and cylindrical body can be formed one.
If the employing said structure then under the situation that higher harmonic components is propagated with fundamental mode or with higher modes, can both prevent that higher harmonic components is to external leaks.In addition, also can suppress the higher harmonic components in intermediate frequency band zone, can positively prevent the unwanted radiation of higher harmonic components to the outside.
(for example will be clipped under the situation of intermediate frequency band 10 five equilibriums in the middle of 2 higher harmonic components, make progress several 4～6 scope from low frequency in) has maximum to the higher harmonic components of intermediate frequency band generally in the central portion office of intermediate frequency band.Therefore, if suppressed the higher harmonic components of the middle body of intermediate frequency band, for example 3.5 order harmonic components and 4.5 order harmonic components etc., then prevent to increase to the effect of external leakage.
In addition, use a λ/4 type choking structures, can suppress the common higher harmonic components and the higher harmonic components of intermediate frequency band simultaneously.Therefore can not raise the cost, and can reduce or suppress the leakage of higher harmonic components to the outside.
In addition, suppress under the situation of higher harmonic components of common higher harmonic components and intermediate frequency band the change of the diameter by cylindrical body and can adjust being limited in scope of wavelength in pipe at the same time.Therefore, wish that the frequency of two higher harmonic components of inhibition is approaching simultaneously.In addition, the wavelength in pipe of TE11 pattern is longer than fundamental mode.Therefore, suppress at the same time under the situation of higher harmonic components of common higher harmonic components and intermediate frequency band, wish that this for example is combined as (N/2) order harmonic components (N 〉=3) propagated with fundamental mode and (N+1)/2 order harmonic components of propagating with TE11 (N 〉=3).
In addition, do not adopt the structure of very big size, make canister can not maximize.Therefore, reduce and use the higher modes higher to propagate,, then in practicality, problem can not take place if suppress the TE11 pattern for higher modes than TE11.
If the employing said structure can suppress with the higher modes higher harmonic components propagated of TE11 pattern for example.Therefore, the internal diameter of the cylindrical body that forms choke groove can be increased, situations such as multipactor discharge and oscillatory instability can be prevented.
In above-mentioned example, use the performance of the 1st～the 4th grade.These numerals also do not mean that special content such as order and position, just use in order to come with other difference.
In addition, adopted the direction of λ/4 type choking structures, for example the open end direction of this choke groove is for towards the structure of input side.But, also can be the structure of the open end of choke groove towards outlet side, in this case, also can access identical effect.

Claims (5)

1. magnetron, have: generate high frequency waves the high frequency waves generating unit, take out described high frequency waves antenna, surround the tubular canister of this antenna and the 1st λ/4 type choking structures of the higher harmonic components that suppresses in described canister, to propagate with fundamental mode, it is characterized in that
Be provided with the 2nd λ/4 type choking structures that suppress the described higher harmonic components in described canister, propagated with higher modes.
2. magnetron has: generates the high frequency waves generating unit of high frequency waves, the antenna that takes out described high frequency waves, the cylindrical body of surrounding the tubular canister of this antenna and in this canister, forming the choke groove of λ/4 type choking structures, it is characterized in that,
According to the two size of the 1st higher harmonic components that suppresses in described canister, to propagate and the 2nd higher harmonic components different with described the 1st higher harmonic components frequency and that in described canister, propagate with higher modes with fundamental mode, set the length of described choke groove
Higher modes are TE11 patterns, and the wavelength in pipe of establishing the 1st higher harmonic components of propagating with fundamental mode is λ g, the free space wavelength of the 2nd higher harmonic components is λ n, the cut-off wavelength of the TE11 pattern of propagating in canister is λ c, the radius of the cylindrical body outer peripheral face of choke groove part is a, and the radius of the canister inner peripheral surface of choke groove part is b, and the length of choke groove is λ g/ 4, in this case, satisfy following relation:
λ c＝π(a+b)
λ g = λ n / 1 - ( λ n λ c ) 2 .
3. the magnetron described in claim 2 is characterized in that,
The frequency of the 1st higher harmonic components is in the frequency of the integral multiple with first-harmonic and have between 2 higher harmonic components of frequency of adjacent size.
4. the magnetron described in claim 2 is characterized in that,
The frequency size of the 1st higher harmonic components is the size of centre in fact of 2 higher harmonic components that is positioned at the frequency of the integral multiple with first-harmonic and the frequency of adjacent size is arranged.
5. magnetron has: generates the high frequency waves generating unit of high frequency waves, the antenna that takes out described high frequency waves, the cylindrical body of surrounding the tubular canister of this antenna and in this canister, forming the choke groove of λ/4 type choking structures, it is characterized in that,
According to the N/2 order harmonic components (N 〉=3) that suppresses in described canister, to propagate and with the two size of (N+1)/2 order harmonic components (N 〉=3) of TE11 mode propagation with fundamental mode, set the length of described choke groove,
If the wavelength in pipe of the N/2 order harmonic components of propagating with fundamental mode (N 〉=3) is λ g, (N+1)/2 the free space wavelength of order harmonic components (N 〉=3) is λ n, the cut-off wavelength of the TE11 pattern of propagating in canister is λ c, the radius of the cylindrical body outer circumference surface of choke groove part is a, and the radius of the canister inner peripheral surface of choke groove part is b, and the length of choke groove is λ g/ 4, in this case, satisfy following relation:
λ c＝π(a+b)
λ g = λ n / 1 - ( λ n λ c ) 2 .
CN200710006187A 2006-01-30 2007-01-29 Magnetron Active CN100583369C (en)

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CN104253009A (en) * 2013-06-27 2014-12-31 乐金电子(天津)电器有限公司 Antenna fixing structure of magnetron for microwave oven
KR102082506B1 (en) * 2018-02-09 2020-02-27 엘지전자 주식회사 Magnetron having enhanced harmonics shielding performance

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JPS62122028A (en) * 1985-06-07 1987-06-03 Toshiba Corp Magnetron for microwave oven
JPH02230640A (en) * 1989-03-03 1990-09-13 Hitachi Ltd Magnetron
KR100209690B1 (en) * 1997-05-31 1999-07-15 구자홍 Magnetron for microwave oven
JPH1125870A (en) * 1997-06-27 1999-01-29 Sanyo Electric Co Ltd Magnetron
JP2004103550A (en) * 2002-07-18 2004-04-02 Matsushita Electric Ind Co Ltd Magnetron
JP3622742B2 (en) * 2002-07-31 2005-02-23 松下電器産業株式会社 Magnetron
JP3944470B2 (en) * 2003-07-30 2007-07-11 東芝ホクト電子株式会社 Magnetron for microwave oven

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