公开(公告)号：US5027077A

公开(公告)日：1991-06-25

申请号：US397619

申请日：1989-08-22

申请人： Michio Yanagisawa ,  Masahisa Ikejiri ,  Hajime Miyazaki ,  Tsukasa Muranaka ,  Kunihiro Inoue ,  Shouichi Uchiyama

发明人： Michio Yanagisawa ,  Masahisa Ikejiri ,  Hajime Miyazaki ,  Tsukasa Muranaka ,  Kunihiro Inoue ,  Shouichi Uchiyama

IPC分类号： G01N27/12

CPC分类号： G01N27/121 ,  G01N27/122

摘要： A humidity sensing apparatus which includes a humidity sensor which detects humidity as a function of impedance is provided. A reference resistor has a predetermined resistance value. A charge switching circuit selectively couples one of the reference resistor or the humidity sensor in series with a reference capacitor which has a predetermined capacitance. A voltage judging circuit determines whether the terminal voltage of the reference capacitor is high or low. A charge/discharge switch selectively charges and discharges the reference capacitor in accordance with the output of the voltage judging circuit. A sensor direction switching circuit inverts the direction of current flowing through the humidity sensor during charging of the reference capacitor. An oscillation frequency counter counts the number of charge/discharge cycles which are repeated during a predetermined time period. A humidity sensor resistance value calculating circuit calculates the resistance value of the humidity sensor in accordance with the number of repeated charge/discharge cycles when the reference capacitor is coupled to the reference resistor for charging and the number of repeated charge/discharge cycles when the reference capacitor is coupled to the humidity sensor during charging. A humidity determining circuit determines the humidity from the resistance value of the humidity sensor calculated by the humidity sensor resistance value calculating circuit.

摘要翻译： 提供一种湿度感测装置，其包括检测作为阻抗的函数的湿度的湿度传感器。 参考电阻器具有预定的电阻值。 充电开关电路选择性地将参考电阻器或湿度传感器中的一个与具有预定电容的参考电容器串联。 电压判定电路判定基准电容器的端子电压是高还是低。 充电/放电开关根据电压判断电路的输出选择性地对参考电容器进行充电和放电。 在参考电容器充电期间，传感器方向切换电路使流过湿度传感器的电流的方向反转。 振荡频率计数器计数在预定时间段内重复的充电/放电循环的数量。 湿度传感器电阻值计算电路根据当参考电容器耦合到用于充电的参考电阻器时的重复的充电/放电循环次数和当参考电压的重复充电/放电循环次数时，计算湿度传感器的电阻值 在充电期间电容器耦合到湿度传感器。 湿度测定电路根据由湿度传感器电阻值计算电路计算出的湿度传感器的电阻值来确定湿度。