| 摘要 |
PURPOSE:To obtain a digital signal in proportion to a relative humidity, by a method wherein a differential signal, which differentiates a pulse from a pulse generator, is amplified in proportion to a resistance value of a humidity-sensitive element, and a time width pulse, which has higher than the given level of said signal, is measured. CONSTITUTION:A pulse signal, generated by means of a pulse generator 1, is differentiated by a condenser 2 and a resistor 3, and the differential signal is inputted to an inversion input terminal of an amplifier 6. A resistance system humidity-sensitive element 5, whose resistance value changes exponent-functionally, is connected to the amplifier 6 in the middle of a return ranging from an output side to the inversion input terminal. This adds a differential signal, having a waveform being symmetrical to a time axis, to the humidity-sensitive element 5, and exerts no polarization action. Additionally, a decay time T, which elapses during the decrease to the given level of the differential signal, changes in a straight line according to changes in a relative humidity. The decay time T opens a gate 9 for the duration of a time T, and a pulse E from a crystal oscillator 10 is measured by counting through the working of a counter circuit 11. |
