Abstract: A heating apparatus capable of heating an article to be heated accommodated within a heating chamber to a degree that the article becomes charred. Illumination intensity of reflected light from the surface of the article illuminated with visible light rays from a light source is detected by an optical sensor, to thereby identify the degree of charring produced in the article, wherein heating operation is controlled on the basis of the identified degree of charring.

Abstract: A door seal arrangement for application to a high-frequency heating apparatus comprising a heating chamber having an access opening and an oven door for openably closing the access opening, for preventing leakage of electromagnetic wave energy through the peripheral area of the oven door. In this door seal arrangement, a plurality of reactance elements of a conductive metal material or a dielectric material having a high dielectric constant are disposed between the flat surfaces of the parallel plate transmission line constituted by the oven door and the heating chamber to extend along the access opening of the heating chamber thereby forming a series resonance circuit connected in parallel with the parallel plate transmission line provided by the oven door and the heating chamber.

Abstract: A high frequency heating apparatus is provided with a hood so constructed as to limit infrared ray energy reaching an infrared ray detecting element for detecting infrared rays radiated from an object to be heated within a heating chamber. In heating apparatus, the influence by the reflection of infrared rays is minimized by making the absorption factor approach to about "1" with blackening the inner surface of the hood. Also, the rotation of a chopper to detect infrared rays radiated from the object through chopping operation is detected by a mechanical switch. The output signal from the infrared ray detecting element is synchronous-rectified in synchronism with the switching operation of the mechanical switch.

Abstract: A high frequency energy apparatus is provided in which high frequency energy is supplied into a heating chamber containing an object to be heated for heating the same. A temperature sensor unit senses either the temperature of air within the heating chamber or the temperature of air flowing out of the heating chamber and a memory unit memorizes a sensed air temperature. When a difference between the air temperature sensed and the memorized temperature reaches a preset value, the amount of supply of the high frequency energy is varied. The preset value is varied with the heating time for heating the object more properly.

Abstract: A microwave oven having special form of a microwave energy radiation arrangement.In order to heat uniformly materials to be cooked, the microwave energy radiation arrangement includes a rotatable conductive rod extending into an oven chamber through a hole located substantially in the center of one oven chamber wall, a rotating conductive arm having one end fixed on the rod so as to extend transversely thereto, and a conductive plate having the center thereof coincident with the axis of the rod and arrayed such that the rotating arm is interposed between the one wall and the conductive plate. Openings for radiating microwave energy into the oven chamber are formed at the periphery of the conductive plate.

Abstract: In a high-frequency energy apparatus, a heat generating element is disposed on a ventilation path of the high-frequency energy apparatus, which path is channeled through a heating chamber. When the heating time is automatically controlled, external air is introduced into the heating chamber, and when the heating time is manually controlled by such a means as a timer, on the other hand, hot air which has been heated by the heat generating element is introduced into the heating chamber so that the deposition of dew on the wall of heating chamber and the obscuring of a viewing panel of the heating chamber due to moisture may be prevented.

Abstract: The present invention involves a high-frequency heating apparatus of the type which comprises a heating chamber for accommodating an object to be heated, a door openably and closably provided for an opening of the heating chamber, a high-frequency energy generator for supplying high-frequency energy to the interior of the heating chamber, a fan for forcibly ventilating the interior of the heating chamber, and a heating chamber air-outlet cooperative with the fan to effect the forcible ventilation for the interior of the heating chamber. Temperature of air flowing out of heating chamber through the heating chamber air-outlet is detected by a temperature sensor to actuate an automatic heating control unit for controlling the supply of high-frequency energy. The apparatus is also provided with a manual heating control unit for manually controlling the heating time.

Abstract: A heating element consisting of a metal pipe, an electric resistance conductor inserted into the metal pipe and a heat resistant insulating material filled between said metal pipe and said electric resistance conductor, characterized in that said heat resistant insulating material is one obtained by coating a first insulating material such as particulate fused magnesia with a second insulating material having a lower melting temperature than that of the first insulating material such as a silicone resin, which has been molten, can maintain an insulation resistance of at least 10.sup.3 M.OMEGA. in an atmosphere at 40.degree. C and a relative humidity of 90%.

Abstract: A microwave oven in which the amount of ventilation for a heating chamber is changed dependent upon whether the heating time is controlled automatically or whether the heating time is controlled by manually setting a timer or a like device, whereby the deposition of dew on the wall of the heating chamber and the obscuring of a viewing panel are prevented.

Abstract: A high frequency energy apparatus for heating an object contained in a heating chamber by high frequency energy which is supplied to the chamber. The temperature of the air in the heating chamber or flowing out thereof is detected. When the temperature of the air reaches a predetermined level, the high frequency energy is controlled. The predetermined level is also changed with the heating time.

Abstract: A gas sensor comprising as a gas sensible material a spinel-type ferrite represented by the general formula AFe.sub.2 O.sub.4 in which A stands for at least one member selected from the group consisting of Li, Mg, Mn, Fe, Co, Ni, Cu, Zn and Pb is provided. In many cases, a catalyzer or a recovering agent need not be incorporated in this gas sensor, and it is characterized in that it is hardly influenced by moisture in the atmosphere.