JP2005183063A - High frequency heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency heating device capable of preventing leakage from a door transparent window in heating to allow a heating state of food to be properly observed. <P>SOLUTION: This high frequency heating device is equipped with a heating chamber 2 for storing food 1 and a door 6 for entering and extracting the food 1 into/from the heating chamber 2. The device is so structured that the transparent window 6b of the door 6 is composed of a slit plate 6b2 having a thickness generally more than three times as much as the depth δ of a superficial skin and heat resistant glass 7 by forming multiple small holes 9 below a cutoff wavelength; a transparent window support part 6d for fixing the transparent window 6b around an opening 6c of a door body 6a for observing the inside of the heating chamber 2, and a slit plate frame part 6b4 with the small holes 9 around the slit plate 6b2 part oppositely contacting the transparent window support part 6d embedded in a preset range (t) are composed; projection parts 6b3 are formed on the transparent window support part 6d oppositely contacting the slit plate frame part 6b4; and the installation interval of the projection parts 6b3 is set not longer than 1/4 wavelength. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a door of a high-frequency heating device that heats food using microwave energy.

  2. Description of the Related Art Conventionally, high-frequency heating apparatuses for the purpose of heating food are provided with a see-through window in a part of the door so that the heating status of the food in the heating chamber can be observed. This see-through window is fitted with a punching metal with a small hole in a thin metal plate or a metal wire made of a thin metal wire so that microwave energy in the heating chamber does not leak outside through the see-through window of the door during heating. Met.

  This punching metal or wire mesh has a structure in which a small hole of about several millimeters is formed with a wavelength that is sufficiently smaller than the cutoff wavelength. Therefore, the user can observe the progress of heating through this small hole without receiving leaked microwave energy from the viewing window.

  In such a perforated window in which a punching metal or a wire mesh made of a thin metal wire is fitted, as shown in Japanese Patent Laid-Open No. 6-104083, small holes are actually clogged with oil, steam, etc. generated in the heating chamber. It is sandwiched with a glass plate or the like so as not to cause the trouble, and is fixed to the see-through window support portion of the metal door.

JP-A-6-104083

  In the prior art described above, there has been a problem that microwave energy leaks through a gap between the punching metal and the metal mesh if they are not electrically short-circuited to the see-through window support portion of the metal door. In addition, when the above punched metal or wire mesh is manufactured by etching or the like, the thickness is several tens to several hundreds of micro and is very thin and is in close contact with the see-through window support of the metal door. There was a problem that it was difficult to short-circuit.

  In order to solve the above-mentioned problems, the present invention is provided in a heating chamber for storing food, a high-frequency oscillator for supplying microwave energy to the heating chamber, and a front surface of the heating chamber, for taking food in and out In a high-frequency heating device that is openable and closable and has a door with a transparent window for viewing food in the heating chamber, a large number of small holes below the cutoff wavelength are provided, and the thickness is about three times the depth of the epidermis. The slit window having the above and the heat-resistant glass constitute a see-through window of the door, and a see-through window support portion for fixing the see-through window around the opening of the door body for observing the heating chamber, and the see-through window support Forming a slit plate frame portion in which a small hole on the outer periphery of the slit plate portion that is in contact with and in contact with the slit is filled in a preset range, and a protrusion on the fluoroscopic window support portion that is in contact with and opposite to the slit plate frame portion Set up , In which the installation interval of the protrusions and the following quarter wavelength.

  As described above, according to the present invention, a heating chamber for storing food, a high-frequency oscillator for supplying microwave energy to the heating chamber, and a front surface of the heating chamber are opened and closed to put food in and out of the heating chamber. In a high-frequency heating apparatus that is free and has a door with a transparent window for viewing food in the heating chamber, a large number of small holes with a cutoff wavelength or less are provided, and the thickness is about three times or more the depth of the epidermis. A see-through window supporting part for fixing the see-through window around the opening of the door body for observing the heating chamber, and forming a see-through window of the door with a slit plate having heat resistance and heat-resistant glass, and the see-through window support part And a slit plate frame portion in which a small hole on the outer periphery of the slit plate portion that is in contact with and in contact with the slit plate frame is filled in a preset range, and a projection is provided on the see-through window support portion that is in contact with and opposite to the slit plate frame portion. Establishment By setting the interval between the projections to be ¼ wavelength or less, the slit plate frame is sandwiched with a heat-resistant glass plate and the slit plate frame is crimped and fixed to the fluoroscopic window support. Therefore, the slit plate frame is attached to the fluoroscopic window support. There is an effect that it is easy to fix tightly, can block leakage of microwave energy to the outside of the heating chamber, improve transparency, and make it easy to observe the heating state of the food in the heating chamber.

  An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a main part of a high-frequency heating device according to an embodiment of the present invention. Reference numeral 2 denotes a heating chamber for storing the food 1 and is made of a metal conductor. A high frequency supply port 3 is provided on the ceiling surface of the heating chamber 2 and radiates microwave energy to the heating chamber 2.

  Reference numeral 4 denotes a high-frequency oscillator that oscillates microwave energy. Reference numeral 5 denotes a waveguide, to which a high-frequency oscillator 4 is fixed. Microwave energy generated by the high-frequency oscillator 4 is guided to the high-frequency supply port 3.

  A door 6 is provided on the front surface of the heating chamber 2 and is used when the food 1 is taken in and out of the heating chamber 2 and can be opened and closed. The door 6 is configured by reference numerals 6a to 6i described below.

  6a is a door body which is a basic structure of the door 6, and when the door 6 is closed, a part thereof is in close contact with the front surface of the heating chamber 2, and the microwave energy in the heating chamber 2 does not leak to the outside during heating. Like that. Reference numeral 6c denotes an opening that is cut out into a rectangular shape in the middle of the door body 6a to form a hole. The opening 6c is provided so that the food 1 in the heating chamber 2 can be observed.

  6d is a see-through window support portion, which is provided around the opening 6c and is formed as a flat portion from the door body 6a portion that is in close contact with the front surface portion of the heating chamber 2. This is a step for fitting a reference 6b described below.

  Reference numeral 6b denotes a see-through window, which is composed of reference numerals 6b2 and 7 described below. Of these, 6b2 is a slit plate that reflects microwave energy. This slit plate is provided with a large number of small holes 9 having a cutoff wavelength or less.

  Further, the slit plate 6b2 constitutes a slit plate frame portion 6b4 in which the slit plate 6b2 portion of the see-through window 6b opposed to and comes into contact with the see-through window support portion 6d fills the small holes 9 in the range t as shown in FIG. doing. The range t varies depending on the dimension of the see-through window support 6d.

  Reference numeral 7 denotes a heat-resistant glass, which is provided to mechanically protect the slit plate 6b2. 4b3 in FIG. 4, which is a perspective view enlarging a part of the see-through window support portion 6d, is a protrusion, and is provided on the see-through window support portion 6d that contacts and faces the slit plate frame portion 6b4 of the slit plate 6b2. The interval between the protrusions 6b3 is set to ¼ wavelength or less.

  The slit plate 6 b 2 and the heat-resistant glass plate 7 of the see-through window 6 b are fixed to the door body 6 a with a silicone adhesive 8. Reference numeral 6f denotes a choke groove, which electrically attenuates microwave energy so as not to leak to the outside when a gap is generated between the door body 6a and the front surface of the heating chamber 2. A choke cover 6g made of a low dielectric loss material is fitted in the opening of the choke groove 6f so that foreign matter from the outside does not enter.

  6h is a door cover which covers the front part of the door body 6a. A cover transparent portion 6i provided on the front surface of the door cover 6h is transparent so that the food 1 in the heating chamber 2 can be observed.

  Next, the operation of this embodiment in the above configuration will be described.

  When the food 1 is heated, the door 6 is opened, the food 1 is placed in the heating chamber 2, the door 6 is closed, and heating is started. Simultaneously with the start of heating, microwave energy is generated from the high-frequency oscillator 4. This microwave energy is guided into the heating chamber 2 from the high-frequency supply port 3 provided in the ceiling portion of the heating chamber 2 through the waveguide 5 to heat the food 1.

  The progress of the heating of the food 1 in the heating chamber 2 can be observed through the cover transparent portion 6i provided on the door 6 and the transparent window 6b. This is because the microwave energy in the heating chamber 2 is reflected by the slit plate 6b2, and the microwave energy does not leak to the outside.

  Here, the see-through window 6b will be described in detail. The see-through window 6b is composed of the slit plate 6b2 and the heat-resistant glass 7 as described above. The slit plate 6b2 is a conductor in which a large number of small holes 9 having a cut-off wavelength or less are provided, and the thickness of the slit plate 6b2 is approximately three times as large as the depth δ of the skin. It is produced in a very thin film with a thickness of several tens to several hundreds of microns.

  The depth δ of the skin is related to the conductivity σ of the material of the slit plate 6b2 and the frequency f of the microwave energy used, and becomes a smaller value as the frequency f increases and the conductivity σ increases.

  In the present invention, the slit plate 6b2 uses, for example, a copper material, aluminum, or stainless steel as a conductor material. These materials have a skin depth δ of about 2 to 10 μm with respect to a frequency of 2.45 (GHz) used in a high-frequency heating apparatus.

  In general, most of the microwave energy is not transmitted if it has a thickness of about 3 times the depth δ of the epidermis. That is, when used as the slit plate 6b2, a thickness of about 3 times or more of the depth δ of the skin is sufficient for shielding microwave energy. In this embodiment, stainless steel (SUS304) is used. The thickness is an extremely thin film of 30 μm.

  This is a remarkably small value compared with the conventional thickness of 0.4 (mm). The reason why the thickness of the slit plate 6b2 is particular is that as the thickness is smaller, the fluoroscopic performance is dramatically improved. On the other hand, when the thickness of the slit plate 6b2 is about 30 μm, the greatest problem is that it is difficult to tightly fix the slit plate 6b2 to the fluoroscopic window support 6d.

  For this reason, the slit plate 6b2 part of the see-through window that faces and comes into contact with the see-through window support part 6d is composed of a slit plate frame part 6b4 filled with small holes all around, and the see-through window support part 6d that comes into contact with and faces the slit plate frame part 6b4. Protruding portions 6b3 are provided, and the interval between the protruding portions 6b3 is set to ¼ wavelength or less, and the slit plate frame portion 6b4 and the see-through window supporting portion 6d provided with the protruding portions 6b3 are arranged to face each other.

  In this way, by arranging the see-through window support 6d provided with the projection 6b3 that is opposed to and in contact with the slit plate frame 6b4, the slit plate frame 6b4 is sandwiched with a heat-resistant glass plate and the see-through window support 6d. When crimping and fixing to the slit window frame portion 6b4, the slit window frame portion 6b4 is easily fixed in close contact with the see-through window support portion 6d, and the leakage of microwave energy in the heating chamber 2 to the outside can be blocked and the see-through property is improved. It becomes easy to observe the heating situation of the food 1 in 2.

  Note that the installation interval of the protrusions 6b3 is set to ¼ wavelength or less in theory if the installation interval of the protrusions 6b3 is set to ½ wavelength or less which is a cutoff wavelength of microwave energy. Since energy cannot pass through this gap, in consideration of safety, it is set to ¼ wavelength or less, which is a half of the cutoff wavelength.

  Thus, by providing the projection window support 6d with the projection 6b3 and the slit plate frame 6b4 on the slit plate 6b2, the slit window 6b2 that shields the microwave energy from the seepage window support 6d is electrically connected. By facilitating the conductive contact, the microwave energy is cut off, and the microwave energy in the heating chamber 2 is prevented from leaking outside through the opening 6c.

It is principal part side surface sectional drawing of the high frequency heating apparatus in one Example of this invention. It is a block diagram of a see-through window. It is an enlarged view of the P section of FIG. It is a partial expansion perspective view of the see-through window support part provided with the projection part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Foodstuff 2 ... Heating chamber 4 ... High frequency oscillator 6 ... Door 6a ... Door body 6b ... Transparent window 6b2 ... Slit plate 6b3 ... Projection 6b4 ...・ Slit plate frame part 6c ・ ・ ・ Opening part 6d ・ ・ ・ Transparent window support part 7 ・ ・ ・ Heat resistant glass 9 ・ ・ ・ Small hole

Claims (1)

A heating chamber (2) for storing food (1), a high frequency oscillator (4) for supplying microwave energy to the heating chamber (2), and a front surface of the heating chamber (2) In a high-frequency heating apparatus having a door (6) that can be opened and closed to enter and exit the heating chamber (2), a large number of small holes (9) having a cut-off wavelength or less are provided, and the thickness is approximately the depth (δ) of the skin. The slit plate (6b2) having about three times or more and the heat-resistant glass (7) constitute a transparent window (6b) of the door (6) and a door body (6a) for observing the inside of the heating chamber (2). A transparent window support portion (6d) for fixing the transparent window (6b) around the opening (6c) of the aperture plate, and a small outer peripheral portion of the slit plate (6b2) portion facing the transparent window support portion (6d). Slit plate frame (6b) with holes (9) filled in a preset range (t) ) And a projection portion (6b3) is provided on the see-through window support portion (6d) in contact with and opposed to the slit plate frame portion (6b4), and an interval between the projection portions (6b3) is set to 1/4 wavelength. A high-frequency heating device characterized by the following.

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