METHOD FOR DETECTING AN UNACCEPTABLY HIGH DEGREE OF CALCIFICATION IN A WATER-CARRYING HOUSEHOLD APPLIANCE

摘要

The invention relates to a method for detecting an unacceptably high degree of scale in an optical measuring section for measuring the turbidity of a lye in a household appliance which operates using calcareous water, such as a washing machine or a dishwasher. The household appliance has a circuit for evaluating the measuring signals from the measuring section (1) and a microprocessor (5) for transferring the measuring results to the sequential control of the appliance. This method is suitable for indicating an unacceptable degree of scale and for taking into account a deterioration of the measuring section due to scaling when determining the turbidity of the lye. Before or during first use of the appliance, a threshold value for acceptable deterioration of the measuring section by future scaling is memorized. During each operating cycle of the appliance, the deterioration of the measuring section during a cycle section which is carried out without turbid lye is measured and converted into a measured value, which is then compared to the threshold value. The microprocessor emits a control signal to the sequential control when the measured value reaches, or nearly reaches, the threshold value.