| 摘要 |
PURPOSE:To enable to perform accurate temperature measurement, by avoiding the pulse width from being affected from external conditions, in the temperature measurement using the circuit in which the resistance value of element converting the temperature into resistance value is converted into pulse width. CONSTITUTION:When the balance of the bridge circuit is unbalanced and the voltage Vi is outputted, it is DC-amplified 2 and inputted to the pulse width modulator 3 to change the pulse width ts of pulse train from the pulse generator 4. The pulse train receiving the pulse width modulation is inputted to the transistor 5 to control ON.OFF operation of the transistor 5 and the effective resistance value Rt between a-b. When the input voltage of the modulator 3 is decreased (increased), the pulse width ts increases (decreases), and the effective resistance value Rt is decreased (increased). Thus, the bridge circuit keeps balancing and variable output is obtained so that the pulse width ts can be determined with the value of the temperature conversion resistance R1. By counting the pulse output through the gate control with the pulse of pulse width ts, the temperature sensed with the conversion resistor can be grasped. |
