| 摘要 |
PURPOSE:To reduce the temperature ripple and yet get the good temperature rise by a method wherein an one-side emitting type face heater formed by substance with large thermal emissivity and a controlling circuit, which energizes in the time ratio in response to the detected temperature, are provided respectively. CONSTITUTION:The face heater unit 3 comprising the one-side emitting type face heater 4, the underside of which serves as an emitting surface and is formed by substance with large thermal emissivity, a reflector 5, a reticulate guard 6 and a reflector 7 is arranged at the center of the top board of a Kotatsu frame 1. A connector 8 containing a temperature detecting thermistor (not shown) therewith is fitted to the face heater unit 3 and a controlling box 10 containing a time proportional controlling circuit (not shown), which is connected through a lead wiring 11 to the connector 8, is also provided. In addition, the energizing to the face heater 4 is performed continuously in case that the detected voltage Vd is higher than the peak value of oscillatory voltage Vo, resulting in causing to raise the temperature in the frame 1 in response to the energizing to the face heater 4 and consequently in lowering the detected voltage Vd. As a result, when the voltage Vd drops below the peak value of the oscillatory voltage Vo, the energizing to the face heater 4 is performed during the period of Vd>Vo or the ratio of energizing time to total operating time is gradually reduced, resulting in accomplishing time proportional controlling. |
