| 摘要 |
PROBLEM TO BE SOLVED: To achieve a higher safety by disabling reusing with ease after the detection of abnormal overheating. SOLUTION: In an overheat prevention circuit 20, a conductive pattern 13 of a heat sensitive sheet is connected in series to a divided resistor 21 and a divided voltage between the both is inputted separately into an input terminal of a comparator 22 and into an input terminal of a comparator 23 as reference voltage. A divided voltage between divided resistors 24 and 25 is inputted as upper limit voltage into the input terminal of the comparator 22 and a divided voltage between the divided resistors 25 and 26 is inputted as lower limit voltage into an input terminal of the comparator 23 among the three divided resistors 24, 25 and 26 connected in parallel with the conductive pattern 13 and the divided resistor 21. Outputs from the comparators 22 and 23 are enabled to be inputted into an input port IP of a microcomputer 27.
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