Abstract: A primary winding (1) and a secondary winding (2) are layered concentrically with a magnetic substance forming a main magnetic circuit (13) and the magnetic resistance of a subordinate magnetic circuit (14) placed between the primary winding (1) and the secondary winding (2) is adjusted, whereby a concentric multilayer winding transformer having an arbitrary coupling coefficient can be provided.

Abstract: A high frequency heating apparatus has an oven-defining structure having an access opening in communication with a heating chamber defined therein, and a hingedly supported metallic door for selectively opening and closing over the access opening. The door has its peripheral area formed with a groove open towards the heating chamber. The bottom of the groove is situated frontwardly of the door with respect to the apparatus. An outerside wall extending from the groove is formed with a plurality of cutouts and a plurality of generally rectangular openings alternating with the cutouts. Each of the cutouts and each of the rectangular openings have one edge positioned on one side of a setup portion, protruding from the bottom of the groove, adjacent the oven-defining structure. The outer wall has a portion bent to protrude transversely into the groove to define a partitioning wall.

Abstract: A high frequency heating apparatus has an oven-defining structure having an access opening in communication with a heating chamber defined therein, and a hingedly supported metallic door for selectively opening and closing over the access opening. The door has its peripheral area formed with a groove open towards the heating chamber. The bottom of the groove is situated frontwardly of the door with respect to the apparatus. An outerside wall extending from the groove is formed with a plurality of cutouts and a plurality of generally rectangular openings alternating with the cutouts. Each of the cutouts and each of the rectangular openings have one edge positioned on one side of a setup portion, protruding from the bottom of the groove, adjacent the oven-defining structure. The outer wall has a portion bent to protrude transversely into the groove to define a partitioning wall.

Abstract: In a microwave heating oven, a safety switch 301 is disposed in an external position relative to a heating chamber 100. A displacement rod 302, which is made of polyprophylene or the like low dielectric constant plastic substance, is disposed through and across the heating chamber 100. Displacement rod 302 serves as a thermal switch, so that at an abnormally high temperature displacement rod 302 melts down, thereby opening the safety switch 301 and disengaging the microwave generator.

Abstract: This invention relates to a fail-safe device for use in heating appliances including an electric oven and a microwave oven. More particularly it relates to a fail-safe device which includes an electronic control circuit 28 for controlling a main circuit of the heating appliance and a mechanical latch for unlocking actuator levers 39, 44 and 45 for fail-safe switches 26, 27, 29 and 30 responsive to the opening and closing movement of a door 3 and to the turning on of a switch 31 in the main circuit upon mechanical actuation of a cook start button 7. There is, therefore, no danger that the appliance may be self-triggered due to the failure of the electronic control circuit 28, incoming noise, a surge of lightning, electrostatic noise, momentary power failure, etc., and become operative when it is not desirable.