Window fog detector

摘要

A vehicle (10) includes a windshield presenting an inner surface (14) including a test section (16) therein. A cooling device (24) is attached to the inner surface (14) for cooling the section (16) to a temperature a few degrees below the temperature of the inner surface (14) adjacent the test section (16). A sensor (26) is disposed adjacent the inner surface (14) for sensing condensation on the test section (16) and for providing a heating signal to a defogging control (28) in response to condensation on the test section (16) for initiating the heating of the surface surrounding the test section (16) by the vehicle heater (18) to prevent condensation from forming on the surface surrounding the test section (16).