Signalverarbeitungsschaltung für Zustandssignale eines resistiven Foliendrucksensors

摘要

The invention relates to a simplified signal processing circuit for processing and analysing signals relating to the status of a force sensing resistor film pressure sensor (10) used in a seat occupation detection device. The circuit provided for by the invention makes use of the fact that an application-specific integrated circuit (3), which in any event is present in a motor vehicle and has digital controlling and regulating functions performed by by a micro control unit (MCU) (2), has a test voltage source (4) which can be switched with very high precision. One end of an electric circuit containing the FSR film (10) is connected to a circuit output VTA of the ASIC (3). The other end of said electric circuit is connected to a port (port0) of the MCU (2). On a reference resistor (R1) connected in series to the FSR film (10), a measuring voltage dependent on current strength which is in turn status-dependent, decreases and crosses the FSR film. Said measuring voltage is fed to an analog/digital converter (ADC) input of the MCU (2) and is transformed into a digital signal indicating the occupation status of the FSR film. In this way, it is possible to evaluate the OCCUPIED / NOT OCCUPIED status of the FSR film (10) and to detect various types of error status by means of only one precisely switchable constant voltage source, one port (port0) of the MCU (2) and one ADC channel.