JPH02227987A - Microwave oven - Google Patents

Abstract

PURPOSE:To prevent effective metal exposure by forming the outer surface of an exterior fitting from an electrically insulative substance, protecting the contour of a door with electrically insulative substance, and installing a plurality of switches on both sides of the grounding wire and live wires of a main circuit. CONSTITUTION:The outer surfaces of exterior fittings 4 and a door 2 are covered with electrically insulative substance, and a plurality of switches 11, 12 actuated in response to opening/closing of the door 2 are installed on both sides of the grounding wire and live wires of a main circuit. When the door 2 is opened, the switches 11, 12 separate all electric parts from the main circuit, and even though any of the parts is grounded to the chassis as the worst event, metal parts in the inner wall of a heating chamber 1 or inside the door 2 are free from risk of becoming live. Thereby the metal parts are exposed when the door 2 is opened, but there is not hazard of electric shocks at all, which allows omission of grounding works.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a microwave oven that does not require grounding work.

BACKGROUND OF THE INVENTION The Electrical Appliance and Material Control Law requires that microwave ovens be grounded in order to prevent electric shocks to users.

And as a configuration that can omit such grounding work,
A double insulation structure and a structure in which no metal is exposed are recognized.

Some double insulation structures have already been commercialized, but no structures in which metal is exposed have been commercialized to date.

Problems to be Solved by the Invention In microwave ovens, in order to shield microwave leakage,
At least the heating chamber and the door body are made of metal. It is quite difficult to provide an electrically insulating layer having a certain thickness on the inner walls of the heating chamber and the door body in order to prevent leakage of microwaves.

The above reason is why a microwave oven with a structure in which no metal is exposed has not been commercialized.

In view of this background, the present invention aims to realize a structure that can reliably prevent leakage of microwaves and effectively prevent metal from being exposed.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention covers the exterior and the outer surface of the door body with an electrical insulator, and has a plurality of switches that operate in response to opening and closing of the door body. It is placed on both sides of the live part of the circuit and the ground wire.

Function The microwave oven of the present invention has no metal parts exposed to the outside when the door is closed, and the door and the heating chamber can form a conventional radio wave seal structure, so there is no problem with radio wave leakage. , and when the door body is opened, all electrical components are disconnected from the main circuit by a switch, and even if any of the components should be grounded to the chassis, metal parts such as the inner wall of the heating chamber or the inside of the door body will be disconnected. will not become a live part, and there is no risk of electric shock. As a result, when the door body is opened, the metal parts are exposed, but there is no risk of electric shock and grounding work can be omitted.

EXAMPLES Below, a microwave oven according to the present invention will be explained with reference to the drawings.

FIG. 2 is a perspective view of the main body of the microwave oven according to the present invention.

A door body 2 is provided at the front of the heating chamber 1 so as to be openable and closable, and an operation panel 3 is arranged thereon. The exterior 4 is formed of an electrically insulating material such as a synthetic resin, or a sheet metal material coated with an electrically insulating material such as a paint film.

FIG. 1 is a side sectional view of such a microwave oven.

The heating chamber 1 accommodates the object to be heated 5 and is made of an electrical conductor to shield microwaves.

The heating chamber 5 includes a magnetron 6 as a microwave generating means.
are coupled via a waveguide 7.

The door body 2 has a tick structure 8 to prevent leakage of microwaves, and this is made of an electrical conductor. A screen 9 made of an electrically insulating material such as synthetic resin is provided outside the tick structure 8 to cover and protect the viewing window 10.

11 and 12 are switches, which are fixed to a bracket 13 made of synthetic resin. 14 is a protrusion provided on the door body;
Reference numeral 15 denotes a lever, which rotates around a fulcrum 16. With this configuration, the switches 11 and 12 open and close in response to the opening and closing of the door body 2.

FIG. 3 is a circuit diagram showing the connection of such switches, in which switches 11 and 12 are connected next to fuse 17 on both sides of the live part of the main circuit and the ground line.

If the door body 2 is closed, the switches 11 and 12 are closed, so when the start of heating is commanded from the operation panel, the control unit 18 starts supplying power to the magnetron 6.

That is, the control unit 18 controls the interior light 20 by the main relay 19.
lights up and rotates the cooling fan 21. Then, power supply to the high voltage transformer 22 is started, the magnetron 6 is operated, and microwaves are irradiated into the heating chamber l.

With this configuration, when the door body 2 is opened, the switch 11 is activated.
and 12 are opened and all components are disconnected from the main circuit. Therefore, even if you touch the inner wall of the heating chamber 1 or the metal parts inside the door body 2, high voltage will not be generated, and even if any of the parts should be grounded to the chassis, the chassis will not be damaged. There are no live parts, and the risk of electric shock is completely avoided.

All components are separated from the main circuit by a spatial distance equal to the distance between the switch contacts, which can be as large as desired.

Only the input terminal and fuse of the switch remain connected to the main circuit even when the door is open, but if they are fixed to a synthetic resin bracket as in this example, these parts can be connected to the main circuit even when the door is open. It is safer because it provides heavy insulation.

Effects of the Invention As described above, the microwave oven of the present invention operates by covering the outer shell with an electrical insulator and inserting a plurality of switches that respond to the opening and closing of the door into the live part of the main circuit and the ground wire. No metal parts are exposed inside, and even if any of the parts should be grounded to the chassis when the door is opened, the metal parts such as the inner wall of the heating chamber or the inside of the door will remain live. This eliminates the risk of electric shock. As a result, when the door body is opened, the metal parts are exposed, but there is no risk of electric shock and grounding work can be omitted.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a microwave oven showing an embodiment of the present invention, FIG. 2 is a perspective view of the main body, and FIG. 3 is a circuit diagram of the microwave oven. l... Heating chamber, 2... Door body, 4...
...Exterior, 6...Microwave generating means, 11
．． 12...Switch. Name of agent: Patent attorney Shigetaka Awano

Claims (1)

[Claims] A heating chamber that stores an object to be heated, a door that can open and close the opening of the heating chamber, a plurality of switches that operate in response to opening and closing of the door, and a microwave generator coupled to the heating chamber. and an exterior that covers the outer shell of the aircraft body, at least the outer surface of the exterior is formed of an electrical insulator, the outer shell of the door body is protected with an electrical insulator, and the plurality of switches are connected to the active part of the main circuit. Microwave oven placed on both sides of electric wire and ground wire.