A capacitive occupancy or proximity detector (10) comprises a heating circuit, an impedance measurement circuit (34, 36, 40) and a diagnostic circuit. The heating circuit includes a heating element (12). The impedance measurement circuit is connected to the heating element so as to measure impedance between the heating element and a node at ground potential. The diagnostic circuit is configured for measuring electrical resistance across the heating circuit and includes a heating current sensor (42), configured for sensing a heating current across the heating circuit, a current supply device (48) for driving a diagnostic current across the heating circuit and a current limiting ground path (50), configured for draining the diagnostic current and for blocking the heating current.
CAPACITIVE OCCUPANCY OR PROXIMITY DETECTOR
22.10.2015
Patent
Elektronische Ressource
Englisch
Diagnostic capacitive occupancy or proximity detector
Europäisches Patentamt | 2017
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