METHOD AND DEVICE FOR FROSTING DETECTION

摘要

PURPOSE: To detect the quantity of the frost adhered to the fin of a heat exchanger. CONSTITUTION: The light emitted from a light emitting element 32 is projected to the end surface 12A of a fin 12 through a projecting lens 201. The scattered light reflected by the end surface 12A of the fin 12 or the surface of a frost 13 through the projecting lens 201 is received by a PSD 33. The output of the PSD 33 is divided by a dividing circuit 209 to provide a displacement signal corresponding to the distance between the light emitting element 32 and the end sun-face 12A of the fin or the surface of the frost 13.