초록 ▼

A humidity detector using a ceramic sensor and a heater to periodically clean the sensor. The output of the sensor is sampled and held while the heater is on. When the detector is turned on, the heater is not started until the sensor has been sampled and held. The timer controlling this operation ca

A humidity detector using a ceramic sensor and a heater to periodically clean the sensor. The output of the sensor is sampled and held while the heater is on. When the detector is turned on, the heater is not started until the sensor has been sampled and held. The timer controlling this operation can be externally reset. When the ceramic sensor is temperature corrected, the humidity output indicates a dew point at a fixed temperature. By adjusting this fixed temperature dew point output according to a sensed temperature, the dew point can be detected.

대표청구항 ▼

A humidity detecting circuit comprising: a humidity sensor providing an AC output; an AC-DC conversion amplifier circuit receiving said AC output of said humidity sensor and providing a DC output; a non-linear amplifier circuit receiving said DC output of said AC-DC conversion amplifier circuit and

A humidity detecting circuit comprising: a humidity sensor providing an AC output; an AC-DC conversion amplifier circuit receiving said AC output of said humidity sensor and providing a DC output; a non-linear amplifier circuit receiving said DC output of said AC-DC conversion amplifier circuit and providing a signal indicating a relative humidity; wherein said humidity sensor is a ceramic humidity sensor and further comprising a heater for selectively heating said humidity sensor to remove impurities on a surface thereof; an output holding circuit receiving said signal indicating a relative humidity; a timer circuit controlling a turning on of said heater and said output holding circuit after a set period, whereby said output holding circuit holds said signal indicating said relative humidity while said heater is operating; and external means for selectively resetting said timer circuit, said resetting means including an external input terminal.