JP2006221958A - Heating method and device by microwave of sheet-like heating object having conductive or magnetic thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new means of heating at high efficiency and uniformly a sheet-like heating object including a conductive thin film or a magnetic thin film. <P>SOLUTION: A sheet-like heating object 1 including a conductive thin film or a magnetic thin film is inserted into a cavity resonator 4 which generates electromagnetic field of TM110, and by utilizing the electric field and current generated in the conductive thin film or magnetic thin film, this is heated directly or indirectly. The insertion location into the cavity resonator 4 can be made changeable according to the size of surface resistance of the thin film. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for heating a sheet-like object to be heated by irradiating microwaves, and in particular, a composite multilayer film sheet in which a conductive thin film or a magnetic thin film is stacked on a substrate is enhanced by microwaves. The present invention relates to a heating method and apparatus capable of heating uniformly and efficiently.

Microwaves are widely used as a heat source for industrial heating furnaces including microwave ovens. Microwaves not only heat water contained in substances, but also act on polar dielectric substances to directly and selectively heat them, so that samples can be heated from outside like conventional heating means. Compared to a device that does this, it has the feature of heating efficiently in a short time.
In recent years, there has been an increasing demand in the fields of solar cells, photocatalysts, sheet pharmaceuticals, printing, electronic devices and the like to selectively and uniformly heat a sheet-like object to be heated using microwaves. The demands range from simple drying to heat treatment and activation. In such a flow of demand, microwaves have been forced to meet demands that include conductive thin films and magnetic thin films beyond the scope of simple dielectric heating.
Usually, microwaves are reflected on the metal surface and cannot enter the metal. However, since the electromagnetic wave is transmitted when the metal thickness is on the order of nm or submicron, the use of microwaves, which has been excluded from conventional targets, is being opened up, especially in the world of thin films.
As a heating device for sheet-like materials by microwaves, a folded line type device that was constructed by bending a waveguide many times was developed, and this bent line was placed in a ring resonator for the purpose of strengthening the electric field. The idea of capturing was devised, but it was used only in a limited range due to problems such as weak electric field and low efficiency.
When a TM110 mode resonance is obtained using a rectangular parallelepiped resonator, a very strong uniform electromagnetic field can be generated as compared with the waveguide type. Using this device, drug drying, printed matter drying, etc. have been studied and as of today, sheet heating exceeds the range of mere dielectric heating, and there is a prospect of being able to respond to heating of conductive thin films. The heating test is in progress.
In the United States, microwave processing using a pure magnetic field and a pure electric field has been proposed in connection with powder metallurgy (Patent Document 3). This is because a microwave is coupled to a system in which both ends of a standard waveguide are short-circuited to resonate TE103, and the electric field is zero and the electric field is maximum except for both ends, and the electric field is maximum. One point where the magnetic field becomes zero is created at equal intervals, and the object to be heated is inserted at the point where the electric field is maximized and the point where the magnetic field is maximized to obtain a characteristic heating result. is there. However, the microwave heating is not limited to heating by a pure electric field and a pure magnetic field, but is usually performed in a space in which an electric field and a magnetic field are present at an appropriate ratio. Although it is a comparison, it is not a practical use. In addition to the TE103 mode described in this document, there are various resonances, and it is a generally known phenomenon that there is a position where a pure electric field and a pure magnetic field are generated by the resonance. Appropriate use of the optimum mode for the object to be heated by microwaves has not been fully developed at present. Therefore, from such a viewpoint, it is necessary and urgent to develop a heating apparatus suitable for an object and to consider a heating method for uniform heating and high-efficiency heating.
US Pat. No. 6,365,885

  The present invention has been made under the background and requirements as described above, and is a new means for uniformly heating a sheet-like object to be heated, particularly a sheet containing a conductive or magnetic thin film, with microwaves. The purpose is to provide.

  In the invention described in claim 1, in order to solve the above-mentioned problem, a TM110 mode electric field is generated in a rectangular parallelepiped cavity resonator, and a sheet-like object to be heated including a conductive thin film or a magnetic thin film is obtained. Provided is a method of passing through the cavity resonator and performing substantially uniform heating with high efficiency.

  The invention described in claims 2, 3 and 4 provides a microwave heating apparatus for carrying out the heating method for a sheet-like object to be heated described in claim 1. The inventions described in claims 3 and 4 provide a microwave heating apparatus capable of selecting an insertion port of a sheet arbitrarily.

  In the present invention, a sheet-like object to be heated having a conductive or magnetic thin film can be uniformly heated with high efficiency.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a simplified partial sectional view showing the basic structure of a sheet to be heated in the present invention, that is, a sheet in which a conductive or magnetic thin film is formed on a substrate, and FIG. 2 shows cavity resonance of the sheet to be heated. FIG. 3 is a perspective view of a microwave heating apparatus having an opening for arbitrarily selecting a position where a sheet to be heated is inserted into the apparatus and passed through the apparatus. It is.

The sheet 1 takes a form in which one or more thin films are formed on a dielectric substrate 2, and at least one of them is a conductive or magnetic thin film 3. FIG. 1 representatively shows the simplest example in which a sheet 1 is composed of a dielectric substrate 2 and a single conductive thin film 3 formed thereon. The conductive thin film 3 includes a layered material that forms a conductive thin film when melted by microwave heating, and also includes a thin film that has conductivity when irradiated with ultraviolet rays or the like. For example, on a glass or resin sheet as the dielectric substrate 2, a conductive thin film coated by means such as sputtering or vapor deposition, or a conductive substance (usually fine powder) is dissolved with an auxiliary material such as a solvent. It has been applied. The thin film 3 is heated by being irradiated with microwaves in the cavity resonator 4. In the above description, the substrate is a dielectric. However, as an extreme case, the substrate itself may be conductive.
The cavity resonator 4 is formed of a rectangular parallelepiped cavity, and has three to six conductor side walls 4a, 4b, 4c, 4d, 4e, and 4f that face each other in the x, y, and z axis directions orthogonal to each other. A waveguide 5 connected to a microwave oscillator (not shown) is coupled to the center of the side wall 4 c, and a microwave is introduced into the cavity resonator 4. An elongated opening 6 extending in parallel with the side wall 4c is provided at a position opposite to the side walls 4a and 4b. The sheet 1 passes through the cavity resonator 4 through the opening 6.
When the surface resistance of the conductive thin film 3 of the sheet 1 is large, for example, several hundred Ω / □ or kΩ / □, it is inserted in a relatively strong electric field in the cavity, and when it is small, that is, several Ω / □. Or when it is several tens of ohms / □, it is inserted where the electric field is relatively weak. The electric field of TM110 is directed in the width direction (z direction) of the sheet 1, and the intensity changes in a sine wave shape in the direction perpendicular to the sheet (x direction), and the wall surfaces of the side walls 4a, 4b, 4c, 4d. Zero at the maximum and maximum at the center between the walls. The magnetic field is generated in such a form as to surround the electric field, there is no component in the width direction (z direction) of the sheet, the strength is maximum on the side walls 4a, 4b, 4c, and 4d, and at the center of the cavity resonator. It becomes zero. Therefore, the strength of the electric field or magnetic field applied to the sheet can be arbitrarily determined by selecting the position where the sheet is inserted into the cavity resonator 4. When the surface resistance of the thin film 3 is large, dielectric heating is performed mainly by the action of the microwave electric field in the cavity, and when it is small, a new electric field is generated in and near the thin film 3 mainly by the action of the magnetic field. As a result, the thin film 3 is heated by an electric current flowing due to an electric field or an electromotive force. In an extreme example in which the insertion position is biased, the sheet 1 is inserted at a position very close to the side wall 4d. In practice, due to the presence of the side wall 4d, it cannot be physically placed at the position of the pure magnetic field, and a certain appropriate distance is taken from the side wall 4d. When the dielectric substrate 2 has a large microwave absorption and it is not desired to heat it as much as possible, the substrate 2 is inserted as close as possible to the side wall 4d.

  When the thin film 3 is a magnetic thin film, it is normally inserted near the side wall 4d of the resonator. However, even in this case, it is necessary to select an appropriate insertion position depending on the surface resistance of the magnetic thin film and its magnetic permeability and thickness, and the optimum position is usually determined experimentally.

  When a conductive thin film or magnetic thin film is inserted at a position where the electric field is strong, the direction of the electric field is the same in the film as in normal dielectric heating, but when this is placed at a position where the magnetic field is strong, the magnetic thin film When there is no conductivity, the direction of the electric field is reversed in the film, and in the case of a conductive thin film or a conductive magnetic thin film, the current flows in the form of a skin current, and the direction is reversed on the back and front. Because of the skin current, it is possible to perform heating with considerably high efficiency even when the conductivity is very high.

  In FIG. 2, the sheet 1 that is the object to be heated passes through the cavity resonator 4 in the x direction indicated by the arrow. The microwave is excited in the cavity through the waveguide 5 to generate a TM110 mode electromagnetic field. The intensity of the electric field in this mode does not change in the width direction (z direction) of the sheet 1 but changes in a sine wave shape with respect to the moving direction (x direction), but by moving the sheet 1 in the x direction, It can be heated uniformly.

  In FIG. 3, a part of the side walls 4a, 4b is composed of a plurality of strip-like opening / closing members 7a, 7b, 7c, 7d,. The opening / closing member 7 is detachable from the cavity resonator 4. When the pair of opposed opening / closing members 7 are removed, this becomes the opening 6 for inserting and moving the seat 1. If necessary, even if a plurality of opening / closing members 7 are removed, there is no problem because the width of the opening is not particularly wide as long as the opening / closing members 7 are separated from each other. In addition, it may sometimes give a good result from the viewpoint of radio wave leakage by adding small metal pieces only at both ends of the opening to make the opening closed at both ends.

  The wall current of the TM110 mode of the rectangular parallelepiped cavity flows in a direction parallel to the electric field, and is parallel to the opening 6 for inserting the sheet. For this reason, if the width of the opening 6 and the wall thickness of the side walls 4a and 4b are appropriately determined, radio wave leakage hardly occurs. As described above, the position of the opening 6 can be easily changed by the method described above.

  The present invention can meet the demand to selectively and uniformly heat a sheet-shaped object to be heated using microwaves in the fields of solar cells, photocatalysts, sheet-form pharmaceuticals, printing, electronic devices, and the like. . Beyond the area of dielectric heating, it can meet the requirements of microwave heating including conductive thin films and magnetic thin films. The purpose of heating ranges from mere drying to heat treatment and activation.

It is sectional drawing which shows the basic structure of the sheet | seat heated by the method of this invention. It is a perspective view of the heating apparatus of the sheet | seat by the microwave which concerns on embodiment of this invention. It is a perspective view of the heating apparatus of the sheet | seat by the microwave which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Composite multilayer sheet 2 Substrate 3 Thin film 4 Cavity resonator 4a ... 4f Side wall 5 Waveguide 6 Opening 7a ... Opening / closing member

Claims (4)

A heating method for a sheet-like object to be heated 1 in which one or a plurality of thin films 3 are formed on a thin substrate 2, and at least one of the thin films 3 is a conductive or magnetic thin film,
The rectangular parallelepiped cavity resonator 4 having the first to sixth six side walls 4a... 4f is substantially perpendicular to the fifth and sixth two side walls 4e and 4f facing each other, and the remaining four side walls 4a and 4b. , 4c, 4d generating a microwave electric field substantially parallel to
Cavity resonance is performed in parallel to the side walls 4c and 4d at a position separated from the third and fourth side walls 4c and 4d substantially parallel to the microwave electric field in the cavity resonator 4 by an arbitrary distance. Passing the sheet-like object to be heated 1 through a vessel 4;
Heating the sheet-like object to be heated 1 with an electromagnetic field generated in the cavity resonator 4. One or a plurality of thin films 3 are formed on a thin substrate 2, and at least one of the thin films 3 is a conductive or magnetic thin film 1 to be irradiated with microwaves. A device for heating,
It has first to sixth six side walls 4a ... 4f, is substantially perpendicular to the fifth and sixth two side walls 4e, 4f facing each other, and is substantially perpendicular to the remaining four side walls 4a, 4b, 4c, 4d. A rectangular parallelepiped cavity resonator 4 for generating parallel microwave electric fields therein;
In the first and second side walls 4a and 4b facing each other substantially parallel to the microwave electric field in the cavity resonator 4, elongated insertion openings 6 extending substantially parallel to the microwave electric field are opposed to each other. Provided in
The sheet-like object to be heated by microwaves is heated by an electromagnetic field generated in the cavity resonator by passing the sheet-like object to be heated 1 through the insertion opening and into the cavity resonator. Heating device. One or a plurality of thin films 3 are formed on a thin substrate 2, and at least one of the thin films 3 is a conductive or magnetic thin film 1 to be irradiated with microwaves. A device for heating,
It has first to sixth six side walls 4a ... 4f, is substantially perpendicular to the fifth and sixth two side walls 4e, 4f facing each other, and is substantially perpendicular to the remaining four side walls 4a, 4b, 4c, 4d. A rectangular parallelepiped cavity resonator 4 for generating parallel microwave electric fields therein;
The first and second side walls 4a and 4b facing each other substantially parallel to the microwave electric field in the cavity resonator 4 have elongated insertion openings 6 extending substantially parallel to the microwave electric field. A plurality of distances from the other pair of opposite third and fourth side walls 4c, 4d substantially parallel to the wave electric field are provided in stages,
The plurality of insertion openings 6 are configured to be selectively openable and closable.
The sheet-like object to be heated 1 is allowed to pass through the cavity resonator 4 through a pair of opposed openings 6 that are selectively opened and heated by an electromagnetic field generated in the cavity resonator 4. A heating apparatus for a sheet-like object to be heated by using a microwave.   A part of the first and second side walls 4a, 4b facing each other substantially parallel to the microwave electric field of the cavity resonator 4 is composed of a plurality of strip-like opening / closing members 7a, 7b,. The opening / closing members 7a, 7b,... Are detachable from the cavity resonator 4. The apparatus for heating an object to be heated by a microwave according to claim 3, wherein

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