A conventional high frequency cooking apparatus which is a kind of the aforementioned cooking apparatus, namely, a microwave oven, has a construction as shown in FIG. 22. A main body 1 of the cooking apparatus has a door 2 at a front face thereof. A material to be cooked is brought in and out of a chamber 3 of the main body by opening and closing the door 2. A high frequency generation device 4 is installed inside the main body 1 and, an emission opening 5 is formed at a top or ceiling face of the chamber 3 to emit high frequency waves into the chamber. The emission opening 5 or a plurality of emission openings 5 are formed in some apparatuses at a rear face or a side face of the chamber other than the top face. A moisture sensor 6 detects the generation of moisture subsequent to cooking, which is utilized to find the progress of cooking. A weight sensor 7 detects the weight of the material to be cooked and is used to adjust the cooking time. These sensors are not always used together, but may be used separately or in combination with other sensors.
During cooking with the use of the thus-constructed high frequency cooking apparatus, there are ways of cooking, e.g., in one way the material is heated only for a preset time; in a different way the cooking is controlled based on values of the humidity and weight detected by the above sensors, that is, the cooking is carried out automatically; in another different way, program cooking is executed, specifically, a heating output and an emission time can be minutely programmed beforehand, so that the cooking is controlled automatically every moment as set by the program. For example, when a frozen meat is to be defrosted and cooked, the meat should be first heated quickly, then moderately, and considerably softly last so as not to be overheated. The meat is properly cooked in the program cooking once the heating intensity and the heating time in each heating state or stage are programmed beforehand. The above-described cooking ways are selected in accordance with the kind of material to be cooked or how to cook the material, resulting in sufficiently satisfactory effects under certain conditions. Optimum cooking conditions for various kinds of materials and cooking ways have been determined from experiments and offered in the form of cookbooks and the like.
Nevertheless, the way of high frequency cooking is unable to control temperatures minutely and delicately, because every material generates a different amount of heat and is greatly influenced by its shape during high frequency heating. Each material cannot be heated uniformly, either. Due to such characteristics of high frequency heating as above, a satisfactory temperature control cannot be achieved when the progress of cooking is indirectly detected by way of the above-described sensing, not by directly detecting the temperature of the material. Meanwhile, if the temperature of the material is to be directly detected, a sensor which does not include metallic parts generating heat by themselves when influenced by high frequency waves or a sensor designed to be resistant to influences by electric waves is needed, although there has been hardly any sensor meeting this requirement put in practical use. In other words, a delicate temperature control based on a temperature change of the material detected during high frequency heating/cooking has never been carried out heretofore. Nor has a control to improve the nonuniform heating state been realized because of the reason that the temperature of the material cannot be detected during cooking. As such, cooking requiring a sensitive temperature control, e.g., vacuum cooking at low temperatures or the like with the use of a high frequency cooking apparatus has not been practiced yet.
In the above-described conventional construction, cooking was done for a fixed time under preliminarily set conditions for menus for which the optimum cooking conditions were already known. Such cooking conditions were conditions conforming to individual cooking apparatuses with no relation to the temperature change of materials. Although it is well known that meat should be heated as rapidly as possible not to exceed 70.degree. C. and vegetables should be heated to 90.degree. C. or higher temperatures, how to set conditions for this way of heating differed in each of the conventional apparatuses. Therefore, the cooking conditions were determined without the temperature change of materials taken into consideration, but with an aim for controlling the operation of each cooking apparatus. In the prior art, unless the optimum cooking condition for each individual cooking apparatus is known, it is hard to perform cooking as required.
The above holds true also for automatic cooking with a programming function. An optimum condition specific to each cooking apparatus and in conformity with each menu should be preliminarily obtained so as to set an optimum program for the menu.
In the case of sensor cooking using various kinds of sensors, the detected physical amount and the temperature of the material are not associated with each other, with the result that the cooking apparatus is controlled based on the ambient temperature or humidity during cooking. While the temperature of the material is directly detected in considerably rare cases, it is practically difficult to detect the temperature of a part of the material for which the temperature is really wanted. Therefore, the cooking apparatus is not controlled using the temperature or temperature change of the material as a parameter.
As discussed hereinabove, the temperature change of the material could not be predicted prior to cooking, or the temperature of the material could not be detected on real-time basis in the middle of cooking in the conventional heating/cooking technology. A good cooking result was hence hard to obtain unless the optimum cooking condition was known. A delicate temperature control in accordance with the temperature of the material was also difficult to achieve.
The present invention has been devised to solve the above-described inconveniences inherent in the prior art, and has for its object to provide a temperature estimation method whereby a temperature change of a material (substance to be cooked) in the middle of cooking is estimated in conformity with the quantity, kind and heating condition of the material. It is also an object of the present invention to provide a cooking apparatus enabling cooking of a material always under required heating conditions irrespective of the amount and kind of the material or the user's experience with the apparatus, etc., with a temperature or temperature change of the material during cooking taken into consideration.