Sensor system for ice or scale deposition on cooling surfaces - has LED and photodiode in refrigerator, or freezer, active surface, with direct light path

摘要

The sensor system detects ice or scale deposition on the cooling surface and refrigerators or freezers. On the respective cooling surface (K) is mounted a light emitting diode (LQ) as a light source and a photodiode (LE) as a light receiver. Between these two components is not a direct visual connection. Preferably the two components lie in the same plane, flush on the cooling surface, with which they form a smooth surface. The two components may be mounted horizontally adjacent in a vertical cooling surface. The light emitting diode may be operated by a push-button switch, in order to maintain the generated heat as low as possible. The sensing function is typically interrupted on opening the door of the refrigerator cabinet. The distance between two diodes is such that it cannot be bridged by a water droplet. Parts of the light path (LW) are in the form of optical fibres, both for thermal decoupling or mechanical matching and sealing.