| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a planar warmer whose safety device has high precision and reliability as a temperature fuse blows without being affected by a short-circuit place.SOLUTION: A planar warmer includes: an AC power supply 20; a heating body 21 provided with a heater wire 22, a fusible body 23, and a temperature detection wire 24 in one body; a temperature detection part 25 which outputs a temperature signal voltage Va; a control part 27 which drives an electric power control element 28; a power supply circuit part 31 which supplies control power; a temperature fuse 36 which blows with heat of a heating resistance 35; and a heating resistance drive part 39 having an active semiconductor for driving the heating resistance. The heating resistance drive part is triggered with a short current flowing as the heater wire 22 and temperature detection line 24 form a closed circuit so as to apply a current of AC power to the heating resistance 35, and consequently even when the short current is weak, power supply to the heater wire 22 can be securely cut off in a short time, so that safety and reliability can be improved.</p> |
