GB1190671A - Temperature Detecting Apparatus. - Google Patents

Abstract

1,190,671. Measuring temperature, electrically. K. NIJO. Jan. 22, 1968, No.3321/68. Heading G1N. [Also in Divisions F4 and G3] A temperature detector comprises two electrodes bridged by water and a switching circuit connected to the electrodes to be operated by a change in electrical resistance between the electrodes due to a physical state transformation of the water between the liquid and solid states. One or both of the electrodes may form part of a hermetically sealed chamber containing the water to which may be added an inorganic salt or organic compound (examples given) to lower its freezing point to a temperature it is desired to detect. Alternatively, the detector may comprise two plate electrodes between which is sandwiched a water absorbent layer open to the air. An arrangement for controlling defrosting of a refrigerator includes two such detectors, one mounted on a cooling fin of the evaporator in a highly cooled position and the other mounted on a plate spaced from a cooling fin in a lens cooled position by a distance corresponding to the thickness of frost at which defrosting is to begin, connected to a control circuit which stops the cooling when both detectors are below their freezing point and restarts the cooling when both detectors are above their freezing point.