1.  Field of the Invention
The present invention relates to an electric rice oven. 
2.  Description of the Related Art
For cooking, rice, adjustment of the water, soaking of the rice in water, and the way of heating and steaming just after the rice is boiled are important. 
In order to cook delicious rice, the rice starch in the rice grain has to be made to undergo a-conversion, and accordingly, it is said that the rice is required to be heated at a temperature higher than 90 deg.  C. for at least 20 min.  Further, the steaming time of the rice just after boiling becomes a key point for enhancing the taste and gloss of the rice. 
Recently, gas type rice ovens using gas as a heat source and electric type rice ovens using electricity as a heat source have been available.  FIG.  5 shows the boiling point reaching/cooling time characteristic (a) of a gas type rice oven and that (b) of an electric type rice oven.  As understood from the figure, the boiling point reaching time and the cooling time using a gas type rice oven are both short, but those of an electric type rice oven are long, that is, the residual heat of an electrical type oven is long as compared with gas type one. 
By the way, an existing electric rice oven has an exhaust system in which an exhaust hole formed in the rear wall or the like of the inside of the oven communicates with an external exhaust pipe, and which discharges steam outside during cooking. 
However, in the above-mentioned conventional electric rice oven, it is a structure only for discharging steam generated during cooking to the outside through the exhaust hole and the exhaust pipe by natural convection.  Accordingly, for example, if rice is steamed at about 120 deg.  C. after it is heated and boiled at 100 deg.  C., the temperature of the inside of the oven rises up immediately to around 150 deg.  C. so that the residual heat existing time becomes long, and that the evaporation of moisture is rapidly carried out, which results in the moisture becoming less so that the rice scorches and sticks to the cooking pot or a net during steaming, and accordingly, a loss of cooking rice corresponding to for example, 20 to 30% occurs.  Further, when the degree of the scorching increases a smoky smell remains and the taste and flavor are deteriorated.