| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a capacitance type physical quantity detection system determining a short circuit fault of self-diagnosis output. <P>SOLUTION: The capacitance type physical quantity detection system is provided with a plurality of capacitance type physical quantity sensors each having: a detection part comprising a movable electrode moving corresponding to the change of physical quantity and a fixed electrode disposed oppositely to the movable electrode; and a C-V conversion circuit including a differential amplifier in which one input is connected to the movable electrode and the other input is connected to a reference potential to detect capacitance change at the time of normal operation which is not self-diagnosis and connected to a self-diagnosis potential which is different from the reference potential at the time of self-diagnosis, and outputting voltage corresponding to capacitance change between the movable and fixed electrodes, wherein: a reference potential of each sensor is the same as each other; the self-diagnosis is performed at the same timing; and self-diagnosis potentials of two selected from the plurality of capacitance type physical quantity sensors are different from each other. <P>COPYRIGHT: (C)2008,JPO&INPIT |
