| 摘要 |
PURPOSE:To detect temperature accurately regardless of stray capacitance by connecting in parallel the base and emitter to the resister of both transistors of PNP type and NPN type, and connecting the inside conductor of heat sensing wire to both base sides and an alternating current power source to both emitter sides. CONSTITUTION:The inside conductor 13 of a heat sensing wire 1 is commonly connected to the base of both transistors T1 and T2 of PNP type and NPN type and one side of an alternating current power source 7 is impressed. The other side of the power source 7 is commonly impressed to the outside conductor 11 of the heat sensing wire 1 and the collector side of transistors T1 and T2 by way of diodes D1 and D2 and resister R3 and R4. Thus, all the induction current incurred by the stray capacitance C received by the heat sensing wire 1 is relieved to the other side of the power source 7 through the conductor 11. As the operation of the transistors T1 and T2 is not affected by the induction current, zero point detection of the alternating current voltage and current wave forms is exactly done. By measuring the voltage impressed to the heat sensing wire 1 and the phase angle of the current on it, temperature signal of the heat sensing wire 1 can be obtained. |
