Capacitive Humidity Sensors Using Highly Durable Polyimide Membrane

Car air conditioners operate in all seasons to keep the cabin temperature cool in summer and warm in winter. In summer, for air conditioning systems without humidity sensors, the system cannot maintain a comfortable humidity level because the dehumidification function stops when the compressor stops. However, a system with humidity sensors can maintain a comfortable level because the system operates with on/off switching control of the compressors based on the information of humidity sensors, even when the engine is stopped. In winter, to reduce the heating load, the air conditioning system, in conjunction with the engine, controls defogging of the windshield using humidity sensors in addition to reducing ventilation loss by increasing the recirculation rate. By adding humidity information, the control of humidity in summer and defogging in winter can minimize the operation of compressors and the engine, and lead to improved fuel consumption without loss of comfort. In particular, in order to prevent energy loss, it is necessary to sense the humidity around windshields to prevent windshields from fogging up in winter.