Bsh Bosch Und Siemens Hausgeraete Gmbh

Andreas Lahrmann

Lothar Knopp

Impermissibly high scaling is ascertained of an optical measurement section in which the turbidity of a washing liquid is detected in a domestic appliance that is operated with hard water, such as a washing machine or dishwasher. The appliance has an evaluation circuit for the measured signals from the measurement section and a microprocessor for binding the measurement results into the sequence control system of the appliance. The system is suitable for indicating impermissibly high scaling and for taking into account attenuation of the measurement section by chalk deposits during the determination of the turbidity of the washing liquid. Before or during the initial commissioning of the appliance, a threshold value for the permissible attenuation of the measurement section by future chalk deposits is stored, during each working cycle of the appliance, the attenuation of the measurement section is measured during a cycle section which is carried out without clouded washing liquid, whereby the attenuation is transformed into a measured value and compared with the threshold value, and the microprocessor outputs a control signal for the sequence control system when the measured value has reached or approximately reached the threshold value.

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Berlin, Germany

Andreas Lahrmann