JPS5851494A - Microwave heating circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to circuit boards for microwave heating.

Conventionally, in order to fix a toner image in dry electrophotography, the toner image is heated (and pressurized) to melt the resin contained in the toner. However, according to this method,
In addition to requiring a so-called waiting time to heat the heating means to a predetermined temperature, a large amount of electric power is required to perform fixing in a short time, which increases the size of the apparatus. For this reason, it has recently been proposed to fix toner images by microwave heating.

In this case, no waiting time is required, but since toner images are generally formed on sheet-like recording materials such as paper or film that have a large surface area and low thermal capacity, heat loss due to convection or thermal radiation is avoided. For example, an apparatus has been proposed in which four slits extending in the axial direction of the waveguide are provided at the center of the magnetic interface of a rectangular waveguide, and a recording material is passed through the slits (Japanese Patent Laid-Open No. 52-20039). ). However, even with such a device, if a toner image is to be fixed in a short time, multiple waveguides are required.
7. In order to solve this problem, the present inventor focused on the microwave strip circuit that is conventionally used for transmitting microwaves without leaking microwaves. This led to the invention of a circuit board that allows microwaves to leak and effectively utilizes the leaked microwaves for heating.

Therefore, an object of the present invention is generally to provide a circuit board that can directly microwave heat sheet materials such as paper, cloth, resin films, etc. It is an object of the present invention to provide a circuit board for microwave heating of toner images, which can solve the above-mentioned problems in heating, can input high-power microwaves, and can downsize an electrophotographic apparatus.

The circuit board for microwave heating according to the present invention is made of a dielectric material having a dielectric constant of 5 or less and a dielectric loss tangent of o, oos or less, with two conductive plates facing each other so that air substantially occupies the space between them. The present invention is characterized in that a spacer is interposed between the conductive plates.

For example, microwave strip resistor circuits are known as microwave strip circuits, but all of them are three-dimensional circuits for confining microwaves, and are made with a high dielectric constant to minimize microwave leakage. A dielectric material is interposed between the conductive plates. However, in the circuit board of the present invention, contrary to these conventional microwave strip circuits, in order to leak microwaves from the circuit, air with a dielectric constant close to a vacuum is substantially occupied between the conductive plates. is formed.

That is, in a conventional microwave strip circuit, as shown in FIG. 1, conductive plates 2 and 3 are usually laminated 7 on both sides of a substrate l made of a dielectric material with a dielectric constant greater than 5. When microwaves are input to the circuit, the electric field is essentially confined between the conductive plates, and as shown by the lines, the electric field has very little deviation and the leakage height is also extremely low. Furthermore, the energy of the microwave input into the circuit is also small, making it impossible to use conventional circuit boards for heating.

-However, as illustrated in FIGS. 2 and 3,
According to the present invention, the conductive plates 2.3 are placed facing each other, and a spacer 4 made of a dielectric material having a dielectric constant of 5 or less and a dielectric loss tangent of 0.005 or less is interposed between them, so that the conductive plates are substantially separated from each other. By configuring the circuit board so that air occupies the entire area, high-energy microwaves can be input into the circuit, and the leakage of the electric field can be increased. Therefore, the material to be heated 5 scattered close to the circuit board can be sufficiently heated by the microwave.

As the conductive plate, for example, a copper plate punched or etched into a predetermined shape is preferably used, and its thickness is usually:
It is 0.01 to 1 m.

In the present invention, as shown in FIGS. 2 and 3,
It is preferable that one conductive plate 2 has a different width from the other conductive plate 3, and both ends of the narrow conductive plate in the longitudinal direction are formed into tapered portions 6 having an inclination angle as input/output ends. The shape of the wide conductive plate 3 is not particularly limited, and may be a rectangular plate as illustrated, or may have other shapes. The conductive plate 3 can also be a rectangular plate smaller in width than the conductive plate 2.

The spacer 4 is made of a dielectric material having a dielectric constant of 5 or less and a dielectric loss tangent of o, oos or less. Specific examples include polysulfon, polyethersulfon, polyphenylene oxide, silicone resin, glass fiber-filled silicone resin, and glass fiber laminated silicon. Resin plates such as resin, polymethylpentene, polystyrene, polyethylene, polytetrafluoroethylene, glass fiber filled polytetrafluoroethylene, glass fiber laminated polytetrafluoroethylene, polyethylene, polypropylene, polystyrene, polysal 7on,
Examples include foamed resin plates such as polyester 5 rusulfone, silicone resin, and polytetrafluoroethylene, woven fabrics and nonwoven fabrics, and tightening fabrics and non-woven fabrics made of glass fibers.

It is preferable that such porous materials such as foamed resin boards, woven fabrics, and nonwoven fabrics have a porosity of 30% or more. This is because the higher the porosity, the lower the dielectric constant of the spacer. Practically, from the point of view of heat resistance, resins made of polytetrafluoroethylene and silicone resin, plates, foams, and glass #! Woven fabrics and nonwoven fabrics made of fibers are preferably used. The thickness of the spacer is usually about 0.3 to 5 mm.

In the present invention: 1. As long as air substantially occupies the space between the opposing conductive plates, the shape of the spacer is not particularly limited, and therefore, the spacer may or may not be continuous in the longitudinal direction of the circuit board. As shown in the figure, since microwave leakage occurs between the peripheries of the conductive plates, it is desirable to interpose a spacer so that air exists between the peripheries of the opposing conductive plates. Therefore, in addition to the spacers 4 shown in FIG. 3, spacers 4 may be provided along both side edges of the narrow conductive plate 2 as shown in FIG.

In the present invention, in order to increase the leakage of microwaves onto the circuit board, that is, the protrusion of the electric field, Fig. 185 and I
As shown in Figure J6, there is a missing part 7 inside one of the conductive plates 2.
It is desirable that a When there is no cutout in the conductive plate, the electric field protrudes only at the outer periphery of the conductive plate, but by forming a cutout in the conductive plate, the electric field extends along the cutout 7 as shown in Figure 6. This is because microwave leakage C also occurs from the periphery of the conductive plate 2, and as a result, the heating area of the material to be heated increases, thereby increasing heating efficiency. Although two rectangular missing parts 7 are shown in FIG. 5, the missing parts may be singular (or may be any plural number, or
The shape may be irregular (or regularly arranged.In place of the missing portions, as shown in FIG. 7, the conductive plate 2 has strip portions 8 along its longitudinal direction. It may be formed to have a protruding part 9 that protrudes from this band-shaped part at a substantially right angle.Also, although not shown, a zigzag pattern such as a wavy wave or a square wave shape that extends continuously from one end to the other end may be formed. Such a design of the shape of the conductive plate increases the length of the periphery surrounding the conductive plate, and is useful for increasing the extension of the electric field at the periphery of the conductive plate.

Furthermore, in the microwave heating circuit board of the present invention, when high-power microwaves are input, in order to avoid discharge between the input end and adjacent conductive plates, as shown in FIG. It is preferable to cover one of the conductive plates, particularly the conductive plate 2 with smaller convergence, with a dielectric material 10 having a dielectric constant of 5 or less and a dielectric loss tangent of o, oos or less. Both surfaces are coated with a dielectric 10. Any of the dielectrics mentioned above can be used as such coating material, but
Polytetrafluoroethylene is preferred from the viewpoint of heat resistance.

As described above, according to the present invention, air having a dielectric constant close to vacuum exists as a dielectric between the opposing conductive plates, so that a large amount of input microwaves leak from the circuit board. For example, if the recording material is placed close to the circuit board, the toner image on the recording material can be directly heated by microwaves, making the device more compact than an electrophotographic device using a waveguide. be able to. In particular, in order to increase the length of the periphery of the conductive plate, a cutout is provided within the conductive plate surface, or a sideward protrusion is provided on the conductive plate, and the dielectric constant is increased on the conductive plate surface. By coating with a dielectric material having a dielectric loss tangent of 5 or less and a dielectric loss tangent of 0 or oos or less, the heating area can be increased without causing any overflow.

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 As shown in FIG. 2, the width is 50111! I, length 300
■, Width 30m-1 Length 30m with a 0.5-thick copper plate underneath
0 fin, thickness 0.51111. The copper plates with both ends tapered are placed facing each other, and between them, a width of 15 mm and a length of 2801111 mm is placed along the longitudinal center. A circuit board was manufactured by disposing polytetrafluoroethylene (dielectric constant 2.6, dielectric voltage!! 0.001) with a thickness of 1 m and tapered portions at both ends as a spacer. Heating paper was placed in parallel on the surface of this circuit board at various heights, and the output was 310W and the frequency was 24.
When 50 MH2 microwaves were input to the circuit board and the height of the microwave leakage from the heating of the heated paper was investigated, it was found to be a maximum of 6 m in practical use. Next, when heating paper was placed horizontally at a height of 0.2 cm above the circuit board and the above microwave was input to the circuit board for 5 seconds, a heating pattern p as shown in Figure 9 appeared on the heating paper. Ta.

Alumina porcelain (dielectric constant 9, dielectric loss tangent 0.0) was used as a comparative dielectric material.
01), and except that the conductive plate was made of copper, a circuit board was manufactured that was exactly the same as in Example 1, and the same circuit board was manufactured using 2450 M
Hz microwave was input for 5 seconds. The heating pattern D8 of the heated paper is shown in Fig. 1θ. It is clear that the heating effect is inferior compared to Example 1.

Example 2 As shown in FIG. 11, a circuit board was manufactured in exactly the same manner as in Example 1, except that a conductive plate 2 having a closed loop-shaped cutout was used as the upper conductive plate. The heating pattern D of the heating paper is shown when the heating paper is arranged at a height of 0.2- from the surface of the circuit board and microwaves of 2450 MHz are input for 5 seconds in the same manner as in Example 1. It is clear that the heating area is significantly larger than in Example 1.

Similarly (when a conductive plate 2 having a shape as shown in FIG. 7 is used as the upper conductive plate 2), a heating pattern D appears along the periphery of the conductive plate on the surface of the substrate, as shown in FIG.

The heating area is still larger than in Example 1.

Example 3 2450M at an output of 250W on the circuit board used in Example 1
When Hz microwave was input for 20 seconds, a discharge occurred at the input end. Therefore, the thickness of both sides of each conductive plate is 10 μm.
A circuit board coated with a polytetrafluoroethylene film was prepared, and microwaves were applied to this circuit board at an output of 250 W for 3 minutes, but no discharge phenomenon was observed. Furthermore, when the output was increased to 350 W and microwaves with a frequency of 2450 MH2 were input, no discharge phenomenon was observed even after 3 minutes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional micro connecting plate, FIG. 2 is a partially cutaway perspective view showing an embodiment of a microwave heating circuit board according to the present invention, and FIG. 3 is an am-1 4 is a sectional view similar to FIG. 3 of the circuit board for microwave heating of the present invention, and FIG. 5 is a partially cutaway perspective view showing another embodiment of the circuit board of the present invention. 136 is a sectional view taken along the line M-■ in FIG. 5, and FIG.
The figure shows another preferred embodiment of the circuit board of the present invention.
3 is a sectional view similar to that of FIG. 9, FIG. 9 is a heating pattern diagram of the circuit board of the present invention, FIG. 10 is a heating pattern diagram of a circuit board as a comparative example, and FIGS. FIG. 6 is another heating pattern diagram. DESCRIPTION OF SYMBOLS 1... Substrate, 2.3... Conductive plate, 4... Spacer, 7... Missing part, 8-... Band-shaped part, 9... Protrusion part,
10...Dielectric coating, A, B, O...Protrusion of electric field, D...Heating pattern. Fig. 1 Fig. 4 Fig. 4 Fig. 7 Fig. 8 Fig. 9 Procedural amendment (voluntary) January 1980 L "Mr. Commissioner of the Japan Patent Office 1, Indication of the case 1988 Patent Application No. 136735 2. Name of the invention Microwave heating circuit board 3. Relationship with the case of the person making the amendment Patent applicant address 3-2-15 Meiwa-dori, Hyogo-ku, Kobe City Name
Band - Kagaku Co., Ltd. 4. Agent 5. Date of amendment order (Showa date, month, day, Showa) 6. Number of inventions increased by amendment 7. Subject of amendment ゛ Detailed explanation of the invention in the specification Column 8, Contents of Amendment As shown in the attached sheet, Contents of Amendment 1, page 8 of the specification, line 1, the following sentence is added following "Good." [Although not shown, the spacer may be a wavy, zigzag, or square wave sheet. ] and correct it. Written amendment to the above procedure (spontaneous) November 4, 1980 Mr. Commissioner of the Japan Patent Office 1. Indication of the case 1982 Patent Application No. 136735 2. Name of the invention Microwave heating circuit board 3. Person making the amendment Relationship Patent applicant address: 2-15 Meiwa-dori, 3-chome, Hyogo-ku, Kobe 9 people
Name: Band Kagaku Co., Ltd., 4, Agent address: 1-8-3-5 Shinmachi, Nishi-ku, Osaka, Japan Date of amendment order: Showa, month, day (Shipping date: Showa)
Date) Contents of the amendment (1) “...Tomoyo” on page 7, line 15 of the specification
[Accordingly, when sheet-like spacers such as corrugated plates or cardboard are used, these spacers may be laminated between conductive plates as shown in FIG. 1.] is added after this. that's all

Claims (1)

[Scope of Claims] (1) Two conductive plates are arranged facing each other so that air substantially occupies the space between them, and the dielectric constant is 5 or less and the dielectric loss tangent is 0.00.
A circuit board for microwave heating, characterized in that a spacer made of a dielectric material having a dielectric strength of 5 or less is interposed between the conductive plates. (2) The circuit board for microwave heating according to claim IJ1, wherein at least one of the conductive plates is formed so as to have a cutout inside thereof. Claim 91 (claim 91) characterized in that one of the conductive plates is formed to have a strip-shaped portion along the longitudinal direction and a protrusion portion protruding from the strip-shaped portion at a substantially right angle. A circuit board for microwave heating according to claim 1, wherein: (4) at least one conductive plate is formed to have a continuous wave pattern extending from one end to the other end thereof; A microwave heating circuit board according to claim 1, wherein at least one of the conductive plates is coated with a dielectric material having a dielectric constant of 5 or less and a dielectric loss tangent of o, oos or less. The microwave heating circuit board according to any one of items 1 to 4.