JP3025538B2 - High frequency band shielding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency band shielding member used for shielding electromagnetic waves having a high frequency such as microwaves (microwaves).

[0002]

2. Description of the Related Art In recent years, technologies using high-frequency electromagnetic waves such as microwaves have been developed. Equipment is being manufactured.

[0003] For example, a high-frequency induction electric furnace is a device for heating a conductor such as a metal. When a high-frequency current is passed through a primary conductor disposed around the conductor, a workpiece corresponding to a secondary side is processed. Since an induced current is generated in the object, the workpiece is heated by Joule heat caused by the induced current.

In addition, the induction hardening device is configured such that a conductor similar to the above is disposed around a steel material, and a high-frequency induction current is applied to the conductor to rapidly heat the surface layer of the steel material, and then rapidly cool and harden. Hardening is performed.

[0005] Further, a microwave furnace uses a microwave having a high frequency of 2450 MHz or 915 MHz to heat a dielectric material that is not a conductor, and is usually placed in a metal furnace called a cavity. A workpiece is placed therein, microwaves are introduced into the cavity to create an electric field therein, and thereby the workpiece is heated through electric lines of force.

As furnaces utilizing microwave heating, those using a batch type cavity and a continuous furnace in which a workpiece is carried on a belt conveyor and passed through a plurality of heating furnaces are known. I have.

[0007]

However, in the above-described heating equipment using high frequency, the high frequency sometimes has an undesired effect on surrounding electric equipment and environment.

That is, since high frequency is an electromagnetic wave generally used for television, radio, and various kinds of communication, there is a problem that high frequency electromagnetic wave leaked from a heating device using high frequency interferes with broadcasting and communication. . In particular,
A heating device using a high frequency has a large output, and even a small output may have a great influence on the surroundings.

[0009] Further, since the high frequency can heat the cells of the living body, the electromagnetic wave leaked from the high frequency heating device may adversely affect the human body and the like. As a countermeasure, a method has been proposed in which the surroundings of the heating device are completely covered with a conductor such as metal to prevent high-frequency leakage, but in this case, the state inside the heating device can be directly observed. Since this is not possible, another problem arises in that it is not possible to perform a proper operation operation according to the heating situation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a high-frequency band shielding member that shields high-frequency waves leaking from a heating device and can easily monitor the internal state of the heating device. To provide.

[0011]

That is, the present invention, which has been made to achieve the above object, is a sheet-like shielding member for shielding high-frequency electromagnetic waves such as microwaves, and comprises a plurality of resin-made transparent or transparent members. Form a thin-film shield layer using a conductive material between the translucent sheet-like bodies, and closely laminate the sheet-like bodies with the shield layer interposed therebetween,
The shield member is configured to cover the entire device for generating high frequency, and the shield member is colored red.
The gist is a high frequency band shielding member characterized by the above.

Here, as the transparent or translucent sheet, various flexible resin films such as vinyl chloride, polyethylene, and nylon can be used. Alternatively, a sheet formed by weaving a transparent or translucent fiber and forming the sheet can be used similarly.

The shield layer may be formed by forming a conductive material such as copper or silver into a very thin film on the surface of the sheet by vapor deposition or plating, or by printing or coating a conductive paint. It may be formed by doing. In addition, as this conductive paint, a material obtained by adding a red paint to a material composed of a conductive filler such as silver or carbon, a binder, and a solvent can be used.

[0014]

According to the present invention, the shield member is configured to cover the entire device for generating high frequency.

Therefore, this high frequency band shielding member is
For example, a heating device that heats a workpiece using high frequency (eg,
For example, by placing it around a microwave oven 2),
Ensures high frequency (eg microwave) leaked from thermal equipment
Can be shut off.

Further , in the present invention, the shield member is colored red. Therefore, when the workpiece is heated and glows red, the glow state can be observed through the shielding member colored red.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A high frequency band shielding sheet according to an embodiment in which a high frequency band shielding member according to the present invention is used in a microwave oven will be described below with reference to the drawings.

FIG. 1 shows a state in which the high frequency band shielding sheet 1 of the embodiment is arranged around a microwave oven 2. The microwave furnace 2 uses a microwave of a high frequency (for example, 2450 MHz) to heat a workpiece which is a dielectric, and a surface of a cavity 3 which is a space inside the microwave furnace has: It is covered with metal such as iron. Further, a part of the wall surface 4 constituting the housing of the microwave furnace 2 is provided so that the inside of the cavity 3 can be observed.
The observation hole 5 is opened.

The high frequency band shielding sheet 1 is a thin and flexible member, as shown in FIG. 2, made of a synthetic resin such as polyethylene (for example, having a thickness of several μm to 0.1 mm). A plurality of transparent films 10 and 11 are laminated, and a shielding layer 12 made of a conductive paint is formed between the transparent films 10 and 11.

The conductive paint for forming the shield layer 12 is obtained by adding a metal powder such as silver to a paint such as red, and the conductive paint is thinly applied to one surface 10a of the transparent film 10 (FIG. For example, the shield layer 12 can be formed by applying the same to the thickness of the transparent films 10 and 11).
Are formed.

More specifically, the conductive paint comprises a conductive filler, a binder such as a synthetic resin, a solvent, and an additive, and exhibits conductivity when cured. Silver powder, carbon black, graphite, silver-plated fine particles, etc. are used as the conductive filler, and epoxy, phenol, acrylic, polyester, and polyester are used as the binder.
Alkyd, urethane, silicon and the like are used. still,
A conductive polymer material may be used as the conductive filler.

The manufacture of such a high frequency band shielding sheet 1 is performed as follows. First, pellets of a synthetic resin such as polyethylene are dry-blended using a Hensial mixer, a super mixer, or the like, and then the powder formed by the dry blending is kneaded with a single-screw or twin-screw extruder. Then, it is extruded as a round or square strand and then cut into a suitable length by a cutting machine.

Next, an extremely thin and flexible transparent film is manufactured by a known melt extrusion method or the like using the material manufactured by the above-mentioned method, that is, a synthetic resin material cut into small pieces.

On the other hand, the conductive paint is a red oil paint and
A liquid paint is obtained by mixing a metal powder such as silver, a binder made of an epoxy resin or the like, and a solvent, and the metal powder is added in an appropriate amount so that the formed shield layer 12 maintains conductivity. I do.

Then, the conductive paint produced in this manner is applied to one surface 10a of the transparent film 10 by screen printing or the like so as to be adhered thereto, and the shield layer 1 is formed.
Form 2 Then, after the applied conductive paint is dried, another transparent film 11 is formed on the surface of the shield layer 12.
Is placed and heated or adhered using an adhesive.

The high frequency band shielding sheet 1 thus formed covers the observation hole 5 of the microwave furnace 2 and covers the entire furnace 2. Therefore, the microwave leaked from the microwave furnace 2 can be reliably shielded.

In particular, since the observation hole 5 penetrates through the wall surface 4 of the microwave oven 2, microwaves are radiated outside from the observation hole 5, but the high frequency band shield of the present embodiment is used. Since the shielding layer 12 made of a conductive paint is formed on the use sheet 1, the leaked microwave can be suitably shielded.

Further, this high frequency band shielding sheet 1
Since the conductive paint is sandwiched between the transparent films 10 and 11, the glowing work inside the cavity 3 can be recognized through the sheet 1.

That is, when the workpiece in the micro furnace 2 is heated by the microwave and glows red, the high frequency band shielding sheet 1 is not taken off, that is, the microwave is completely shielded. This has a remarkable effect that the glowing state can be observed through the high frequency band shielding sheet 1.

It should be noted that the present invention is not limited to the above-described embodiments, but can be practiced in various modes without departing from the gist of the present invention. For example, a shield layer 12 made of a conductive paint may be further formed on one surface or both surfaces of the high-frequency band shielding sheet 1 of the above-described embodiment. 1 may be laminated to form one sheet. In this case, there is an advantage that the high-frequency shielding property is further improved.

Further, in the above-described embodiment, an example in which the high frequency band shielding sheet 1 is used for the microwave oven 2 has been described. However, it goes without saying that the present invention can be applied to various devices using high frequency. For example, it can be used for a high-frequency induction heating apparatus for heating metal rolling and forging, or for heat treatment such as quenching and annealing, and can also be used for microwave ovens, high-frequency welding, high-frequency electrolysis, and the like.

[0032]

According to the present invention, since the shielding member covers the entire device, there is an advantage that the electromagnetic wave shielding property is high. Moreover, in the present invention, since the shield member is colored red, the red heat state of the workpiece to be processed can be accurately observed through the shield member in a state where high frequency is shielded.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view showing a state in which a high frequency band shielding sheet according to an embodiment of the present invention is used in a microwave oven.

FIG. 2 is a partially cutaway perspective view showing an enlarged high frequency band shielding sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... High frequency band shielding sheet 2 ... Microwave furnace 10, 11 ... Transparent film 12 ... Shield layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H05K 9/00

Claims (1)

(57) [Claims] 1. A sheet-like shielding member for shielding high-frequency electromagnetic waves such as microwaves, wherein a thin film using a conductive material is provided between a plurality of resin-made transparent or translucent sheet-like bodies. the shielding layer is formed, as well as laminated in close contact with the sheet-like body across the shield layer, and configured to cover the entire apparatus for generating a high-frequency a member for the shield, further, red member for the shield Characterized by being colored
High-frequency band shield member to be.