| 摘要 |
PURPOSE:To surely detect the boiling point regardless of the amount of water and the kind of container by the methods wherein the tempeature of the water in a water heating container is detected indirectly while the boiling is detected with a means based upon the gradient of temperature rise after a predetermined temperature is reached. CONSTITUTION:When a key switch 4 is closed, a microcomputer 1 turns a bilateral thyristor 7 ON through a transistor 10 and a photocoupler 9 so as to energize a heat generating body 6 in order to start heating. Next, the microcomputer 1 receives temperature data of a temperature sensor 2 abutting against the bottom of a container 12 after being converted into digital data at an A/D converter 3 and counts the time tO necessary for the ascent of 2 degree after the temperature in the container 12 exceeds the starting temperature for gradient detection (about 70 deg.C). At this time, when the time tO exceeds a predetermined time T1, the water is judged to be already in boiling state. Said time tO is once memorized and compared with a next similar time tN and the boiling is judged when the ratio of tO to tN reaches a predetermined ratio, and the energizing to the heat generating body 6 is made to be stopped. |
