JP2010108711A - Microwave oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave oven capable of effectively doing away with heating shortage occurring around a rotating shaft of a rotating antenna. <P>SOLUTION: The microwave oven 1 includes a heating room 5 housing a heated object, a lower magnetron 18 oscillating microwaves for microwave-heating the heated object in the heating room 5, a lower waveguide 14 coupling the lower magnetron 18 and the heating room 6 to transmit the microwaves, and a metal-made lower rotating antenna 24 located at a heating room 6 side of a lower power-feeding port 17 coupling the lower waveguide 14 and the heating room 6 and supported by a metal-made lower rotating shaft 27. A parallel flat-plate line for transmitting the microwaves is formed with the lower rotating antenna 24 and a top face of a bottom wall 16 of the heating room 6, and at the same time, an end part of the lower rotating antenna 24 extended from the lower rotating shaft 27 is arranged in the vicinity of the lower rotating shaft 27. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a microwave oven that radiates microwaves (high-frequency energy) into a heating chamber using a rotating antenna and heats an object to be heated such as food.

  In recent years, the rotating antenna made of a metal flat plate is rotated to change the direction of microwave radiation in the heating chamber, and the microwave is diffused in the heating chamber to perform heating so that the entire heating chamber can be heated as uniformly as possible. A range has been developed.

  In this case, the rotating antenna is provided at the bottom of the heating chamber or in addition to the ceiling. The rotating antenna is disposed on the heating chamber side of the power feeding port formed in the heating chamber, and is supported by a metal rotating shaft. One end of the waveguide is connected to the power supply port, and the other end of the waveguide is connected to a magnetron provided outside the heating chamber.

Then, the microwave oscillated by the magnetron is transmitted through the waveguide and reaches the rotating antenna through the power feeding port. Since this rotating antenna forms a parallel plate line that transmits microwaves with the wall surface of the heating chamber (cavity), the microwave transmitted from the feeding port to the rotating antenna is transmitted through this parallel plate line to the rotating antenna. It will be radiated | emitted in a heating chamber from an edge part. Since this rotating antenna is rotated by a motor via a rotating shaft, the microwave radiated from the end of the rotating antenna is diffused into the heating chamber.
JP 2008-166221 A

  Here, since the conventional rotating antenna has a shape extending outward from the rotating shaft in one direction, two directions or more, microwaves inevitably radiate strongly toward a position away from the rotating shaft. Will be.

  However, the rotating shaft is usually arranged at the substantially central portion of the bottom (ceiling) of the heating chamber, and the object to be heated is usually placed at the central portion of the heating chamber (actually the central portion on the tray). Therefore, there has been a problem that the portion corresponding to the rotation axis, that is, the vicinity of the center of the object to be heated is inevitably insufficient.

  The present invention has been made to solve the conventional technical problems, and an object of the present invention is to provide a microwave oven that can effectively eliminate insufficient heating that occurs in the vicinity of the rotating shaft of a rotating antenna. It is what.

  A microwave oven according to the present invention includes a heating chamber for storing an object to be heated, a magnetron for oscillating microwaves for microwave heating the object to be heated in the heating chamber, and a coupling between the magnetron and the heating chamber. A microwave transmitting microwave, and a metal rotating antenna that is located on the heating chamber side of the feeding port connecting the waveguide and the heating chamber and is supported by a metal rotating shaft. The rotating antenna and the heating chamber wall surface form a parallel plate line for transmitting microwaves, and the end of the rotating antenna extending from the rotating shaft is disposed in the vicinity of the rotating shaft.

  The microwave oven according to a second aspect of the present invention is characterized in that both ends of the rotating antenna extending in two directions from the rotating shaft are opposed to each other.

  A microwave oven according to a third aspect of the present invention is characterized in that in each of the above inventions, both end portions of the rotating antenna extending in two directions from the rotating shaft are directed toward the rotating shaft.

  A microwave oven according to a fourth aspect of the present invention is characterized in that, in each of the above inventions, the rotating antenna from the rotating shaft to the end is formed in an arc shape.

  A microwave oven according to a fifth aspect of the present invention is characterized in that, in each of the above inventions, the rotating antenna has a line-symmetric shape with respect to a line passing through the rotation axis.

  According to the present invention, a heating chamber that accommodates an object to be heated, a magnetron that oscillates microwaves for microwave heating the object to be heated in the heating chamber, and the magnetron and the heating chamber are coupled to each other. In a microwave oven equipped with a waveguide that transmits microwaves, and a metal rotating antenna that is positioned on the heating chamber side of the power feeding port connecting the waveguide and the heating chamber and supported by a rotating shaft. A parallel plate line that transmits microwaves is formed between the antenna and the heating chamber wall, and the end of the rotating antenna that extends from the rotating shaft is placed near the rotating shaft, so it consists of the rotating antenna and the heating chamber wall. The microwave transmitted through the parallel plate line is emitted from the end of the rotating antenna located near the rotation axis.

  Thereby, the heating performance in the vicinity of the rotating shaft can be strengthened, and the insufficient heating in the vicinity of the center of the object to be heated can be effectively solved.

  In particular, if both ends of the rotating antenna extending in two directions from the rotating shaft are opposed to each other as in the invention of claim 2, the microwaves radiated from both ends interfere with each other and are absorbed by the object to be heated. Therefore, the heating performance near the center can be further improved.

  Further, the heating performance in the vicinity of the center of the object to be heated can also be improved by directing both end portions of the rotating antenna extending in two directions from the rotating shaft to the rotating shaft side as in the invention of claim 3.

  Further, if the rotating antenna extending from the rotating shaft to the end portion is formed in an arc shape as in the invention of claim 4, the microwave leaking from the rotating shaft to the end portion is reduced, and the heating performance in the vicinity of the rotating shaft is reduced. Can be further improved.

  Furthermore, if the rotating antenna is made symmetrical with respect to the line passing through the rotation axis as in the invention of claim 5, the left and right line lengths are the same, and the heating performance near the center of the object to be heated is improved. Can do.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a microwave oven 1 to which the present invention is applied, and FIG. 2 is a sectional view taken along line AA of FIG. In FIG. 1, reference numeral 1 denotes a commercial microwave oven of the embodiment, 2 is a main body of the microwave oven 1, 3 is a door disposed on the front surface of the main body 2, and 4 is a user inputting various information to the microwave oven 1. Therefore, the operation panel is disposed on the front surface of the main body 2 and above the door 3.

  Next, in FIG. 2, reference numeral 6 denotes a heating chamber that is configured in the main body 2 and stores an object to be heated such as food, 7 is a partition plate made of resin, for example, disposed in the upper part of the heating chamber 6, and 8 is a heating chamber. 6 is a tray (food placing shelf) made of ceramic, for example, disposed at the bottom of the inside. Reference numeral 9 denotes an upper waveguide connected to the heating chamber 6 at an upper feeding port 12, one end of which is formed in the substantially central portion of the top wall 11 of the heating chamber 6. An upper magnetron connected to the end. Reference numeral 14 denotes a lower waveguide connected to the heating chamber 6 at a lower feeding port 17, one end of which is formed in the substantially central portion of the bottom wall 16 of the heating chamber 6, and 18 denotes the other end of the lower waveguide 14. It is a connected lower magnetron. The magnetrons 13 and 18 and the upper and lower waveguides 9 and 14 are disposed outside the heating chamber 6 in the main body 2.

  The upper and lower waveguides 9 and 14 are coupled between the upper and lower magnetrons 13 and 18 and the heating chamber 6 via the upper and lower power feeding ports 12 and 17, respectively, and the microwaves oscillated by the upper and lower magnetrons 13 and 18 are heated. Are transmitted to the ceiling and the bottom of each.

  Reference numeral 21 denotes an upper rotating antenna which is disposed in a space between the partition plate 7 and the top wall 11 of the heating chamber 6, is coupled to the upper waveguide 9 in a radio wave manner, and is rotatably attached. The upper rotating antenna 21 is provided for radiating the microwave oscillated by the upper magnetron 13 from the ceiling into the heating chamber 6 and diffusing the microwave into the heating chamber 6, and is a highly conductive metal such as aluminum. It is made of a flat plate and is located on the heating chamber 6 side of the upper power supply opening 12. An upper motor 22 is attached to the outside of the upper waveguide 9, and a metal upper rotating shaft 23 is connected to a resin rotating shaft of the upper motor 22. The upper rotating antenna 21 is attached to the lower end of the upper rotating shaft 23 through the opening 12 and into the heating chamber 6. In addition, due to such a structure, the upper rotating shaft 23 is positioned at a substantially central portion of the top wall 11 of the heating chamber 6.

  Reference numeral 24 denotes a lower rotating antenna which is disposed in a space between the tray 8 and the bottom wall 16 of the heating chamber 6, is coupled to the lower waveguide 14 in a radio wave manner, and is rotatably attached. The lower rotating antenna 24 is provided to radiate the microwave oscillated by the lower magnetron 18 from the bottom into the heating chamber 6 and diffuse the microwave into the heating chamber 6. It is comprised with the metal flat plate, and is located in the heating chamber 6 side of the lower electric power feeding opening | mouth 17. A lower motor 26 is attached to the outside of the lower waveguide 14, and a metal lower rotating shaft 27 is connected to a resin rotating shaft of the lower motor 26. The lower rotating antenna 24 is attached to the upper end of the lower rotating shaft 27 through the opening 17 and into the heating chamber 6. Further, due to such a structure, the lower rotating shaft 27 is positioned at a substantially central portion of the bottom wall 16 of the heating chamber 6.

  Next, FIG. 3 shows a plan view of the lower rotating antenna 24. The lower rotating antenna 24 extends in two directions from the lower rotating shaft 27, and each of the extended sides 28 and 29 has a C-shaped arc shape and an inverted C-shaped arc shape. That is, the lower rotating antenna 24 has a shape in which one end of each of the C-shaped side 28 and the inverted C-shaped side 29 is connected by the lower rotating shaft 27. The other end of each side 28, 29, that is, both end portions 28 A, 29 A of the lower rotating antenna 24 are located in the vicinity of the lower rotating shaft 27. Further, both end portions 28A and 29A of the lower rotating antenna 24 face each other in a state facing the lower rotating shaft 27 side, that is, a state facing inward. Further, in the lower rotating antenna 24, the sides 28 and 29 are symmetrical with respect to the line L 1 passing through the lower rotating shaft 27.

  The lower rotary antenna 24 and the upper surface of the bottom wall 16 of the heating chamber 6 form a parallel plate line that transmits microwaves, and the microwaves transmitted through the lower waveguide 14 exit from the lower feeding port 17. The lower rotary antenna 24 is transmitted, and a parallel plate line between the lower rotary antenna 24 and the upper surface of the bottom wall 16 of the heating chamber 6 is transmitted and radiated from both end portions 28A and 29A.

  In this case, the sum of the distance from the magnetron antenna 18A of the lower magnetron 18 to the end portion 28A of the lower rotating antenna 24 and the sum of the distance from the magnetron antenna 18A of the lower magnetron 18 to both end portions 29A of the lower rotating antenna 24 are: The size of the lower rotating antenna 24 is determined so as to be an integral multiple of a half wavelength of the microwave considering the in-tube wavelength in the waveguide. Thus, impedance matching for microwave transmission is achieved, and microwaves are efficiently emitted from both end portions 28A and 29A.

  Next, FIG. 4 shows a plan view of the upper rotating antenna 21. The upper rotating antenna 21 extends from the upper rotating shaft 23 in four directions, and the extended two sides 31 and 32 have arc shapes of opposite shapes facing each other. The remaining two sides 33 and 34 are linear and extend outward in substantially opposite directions. Since the upper rotating antenna 21 is suspended from the top wall 11, the two sides 33 and 34 play a role of balancing. Further, the upper rotary antenna 21 has sides 31 and 33 and sides 32 and 34 that are line-symmetric with respect to a line L2 passing through the upper rotary shaft 23.

  The upper rotary antenna 21 and the lower surface of the ceiling wall 11 of the heating chamber 6 form a parallel plate line that transmits microwaves. The microwaves transmitted through the upper waveguide 9 exit from the upper feeding port 12. To the upper rotary antenna 21, transmitted through a parallel plate line between the upper rotary antenna 21 and the lower surface of the top wall 11 of the heating chamber 6, and radiated from the end portions 31 </ b> A to 34 </ b> A of the sides 31 to 34. become.

  In this case, the sum of the distances from the magnetron antenna 13A of the upper magnetron 13 to the respective end portions 31A to 34A of the upper rotary antenna 21 is an integral multiple of 1/2 wavelength of the microwave considering the in-tube wavelength in the waveguide. The dimensions of the upper rotating antenna 21 are determined so that Thereby, impedance matching for microwave transmission is taken, and microwaves are efficiently radiated from the end portions 31A to 34A.

  The heating operation of the object to be heated (food etc.) in the heating chamber 6 with the above configuration will be described. The door 3 is opened, an object to be heated is inserted into the heating chamber 6, placed on the approximate center of the tray 8, and the door 3 is closed. In this state, the lower rotary shaft 27 substantially corresponds to the lower part of the center of the object to be heated. Thereafter, when a predetermined heating menu is selected on the operation panel 4 and the start button is operated, the upper and lower magnetrons 13 and 18 start to oscillate, and the upper and lower motors 22 and 26 also start to operate, and the upper rotary antenna 21 and the lower rotary antenna. 24 begins to rotate.

  Microwaves oscillated by the upper magnetron 13 are transmitted through the upper waveguide 9 from the magnetron antenna 13A, exit from the upper feeding port 12, reach the upper rotating antenna 21, and the lower surface of the top wall 11 and the upper rotating antenna 21. A parallel plate line is transmitted between the edges 31 </ b> A to 34 </ b> A of the sides 31 to 34 and radiated into the heating chamber 6. Since the upper rotating antenna 21 is rotated by the upper motor 22, the microwave radiated from the upper rotating antenna 21 is radiated from the ceiling to the entire inside of the heating chamber 6.

  In this case, since the sides 31 and 32 of the upper rotating antenna 21 have opposing arc shapes, the microwaves radiated from the end portions 31 </ b> A and 32 </ b> A go to the center portion in the heating chamber 6. These sides 31 and 32 have an arc shape, and there are no corners in the line extending from the upper rotary shaft 23 to the end portions 31A and 32A, so that there is little microwave leakage before reaching the end portions 31A and 32A. Become. Thereby, the amount of microwave radiation from the end portions 31A and 32A can be ensured. Further, since the sides 33 and 34 are directed outward, the microwaves radiated from the end portions 33 </ b> A and 34 </ b> A are directed to the outer portion in the heating chamber 6. Furthermore, since the upper rotary antenna 21 has a line-symmetric shape with respect to the line L2 passing through the upper rotary shaft 23, the upper rotary antenna 21 is not evenly distributed in the heating chamber 6 from the ceiling, but is substantially uniform throughout the entire heating chamber 6. Microwaves will be emitted.

  On the other hand, the microwave oscillated by the lower magnetron 18 is transmitted through the lower waveguide 14 from the magnetron antenna 18A, exits from the lower feeding port 17, reaches the lower rotating antenna 24, and rotates on the upper surface and the lower portion of the bottom wall 16. A parallel plate line between the antennas 24 is transmitted and radiated into the heating chamber 6 from the end portions 28 </ b> A and 29 </ b> A of the sides 28 and 29. Since the lower rotating antenna 24 is rotated by the lower motor 26, the microwave radiated from the lower rotating antenna 24 is also radiated into the heating chamber 6 from the bottom.

  In this case, since the end portions 28A and 29A of the sides 28 and 29 of the lower rotating antenna 24 are disposed in the vicinity of the lower rotating shaft 27, a parallel plate line constituted by the lower rotating antenna 24 and the upper surface of the bottom wall 16 is used. Is radiated from the end portions 28A and 29A of the lower rotating antenna 24 located in the vicinity of the lower rotating shaft 27. As a result, the heating performance in the vicinity of the lower rotating shaft 27 is enhanced, and the insufficient heating in the vicinity of the center of the object to be heated located near the lower rotating antenna 24 can be effectively eliminated.

  In particular, since both end portions 28A and 29A of the lower rotating antenna 24 extending in two directions from the lower rotating shaft 27 are opposed to each other, the microwaves radiated from both end portions 28A and 29A interfere with each other, It will be absorbed by the object to be heated. Thereby, the heating performance near the center of the object to be heated is further improved.

  Furthermore, since both end portions 28A and 29A of the lower rotating antenna 24 extending in two directions from the lower rotating shaft 27 face the lower rotating shaft 27 side, the heating performance near the center of the object to be heated is further improved. At this time, since the sides 28 and 29 of the lower rotating antenna 24 extending from the lower rotating shaft 27 to the ends 28A and 29A have an arc shape, the micro leaks from the lower rotating shaft 27 to the ends 28A and 29A. Waves also decrease, and the heating performance in the vicinity of the lower rotating shaft 27 is further improved.

  Here, since the microwaves reflected by the end portions 28A and 29A are radiated from the lower rotating antenna 24 of the lower rotating shaft 27, the object to be heated located near the lower rotating antenna 24 by these. Thus, the heating capacity near the center of the substrate is remarkably improved as compared with the conventional case.

  Furthermore, since the lower rotating antenna 24 has a line symmetrical shape with respect to the line L1 passing through the lower rotating shaft 27, the left and right line lengths are the same, and the heating performance near the center of the object to be heated is improved. Will be able to.

  In the embodiment, the present invention has been described with a microwave oven in which antennas are provided on both the bottom and ceiling of the heating chamber. However, the present invention is also applied to a microwave oven in which antennas are provided only on either the bottom or the ceiling. The invention is effective.

It is a perspective view of the microwave oven to which this invention is applied. It is the sectional view on the AA line of the microwave oven of FIG. It is a top view of the lower rotating antenna of the microwave oven of FIG. It is a top view of the upper rotating antenna of the microwave oven of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microwave oven 6 Heating chamber 9 Upper waveguide 11 Top wall 12 Upper feed port 13 Upper magnetron 14 Lower waveguide 16 Bottom wall 17 Lower feed port 18 Lower magnetron 21 Upper rotating antenna 22 Upper motor 23 Upper rotating shaft 24 Lower rotation Antenna 26 Lower motor 27 Lower rotating shaft 28, 29 Side 28A, 29A End

Claims (5)

A heating chamber for storing an object to be heated;
A magnetron that oscillates microwaves for microwave heating the object to be heated in the heating chamber;
A waveguide for transmitting microwaves by coupling between the magnetron and the heating chamber;
In a microwave oven provided with a metal rotating antenna that is located on the heating chamber side of a power feeding port connecting the waveguide and the heating chamber and supported by a metal rotating shaft,
A parallel plate line for transmitting microwaves is formed by the rotating antenna and the heating chamber wall surface, and an end of the rotating antenna extending from the rotating shaft is disposed in the vicinity of the rotating shaft. microwave.   The microwave oven according to claim 1, wherein both ends of the rotating antenna extending in two directions from the rotating shaft are opposed to each other.   The microwave oven according to claim 1 or 2, wherein both ends of the rotating antenna extending in two directions from the rotating shaft are directed toward the rotating shaft.   The microwave oven according to any one of claims 1 to 3, wherein the rotating antenna extending from the rotating shaft to the end portion is formed in an arc shape.   The microwave oven according to any one of claims 1 to 4, wherein the rotating antenna has a line-symmetric shape with respect to a line passing through the rotation axis.

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