Patent Number: 6,297,641

Title: Signal-processing circuit arrangement for status signals of a resistivefoil pressure sensor

Abstract: The simplified signal-processing circuit arrangement for processing andevaluating signals indicative of the status of an FSR-foil pressure sensorutilized in a seat-occupancy detection device, makes use of the fact thatan application-oriented, integrated circuit, present in a motor vehiclehaving digital open-loop and closed-loop control functions implemented ina microcontroller MCU, contains a highly precise, switchable test-voltagesource. One end of a circuit containing the FSR-foil is connected to aswitching output VTA of the ASIC carrying the highly precise test voltage.The other end of this circuit is connected to a port of the MCU. Ameasuring voltage, which is a function of the status-contingent currentintensity through the FSR-foil, drops off across a reference resistorconnected in series to the FSR-foil, is fed to an analog-digital converterinput of the MCU, and is converted therein into a digital signalindicating the occupancy status of the FSR-foil. Thus, using only oneprecise, switchable, d.c. voltage source, one port of the MCU and one ADCport, it is possible to evaluate the OCCUPIED/NOT OCCUPIED status of theFSR-foil, as well as to detect various fault conditions.

Inventors: Mattes; Bernhard (Sachsenheim, DE), Nitschke; Werner (Ditzingen, DE), Drobny; Wolfgang (Heilbronn, DE), Karl; Otto (Leonberg-Hofingen, DE), Hanussek; Adrian (Muhlacker-Lienzingen, DE), Schadler; Peter (Ludwigsburg, DE)

Assignee:

International Classification:

Expiration Date: 10/02/2013