| 摘要 |
<p>A displacement converter in which a pressure difference is determined by detecting capacitances C1 and C2 between fixed electrodes (3, 4) and a diaphragm (1), which receives pressure differences on both of its sides and can be displaced. The pressure difference is output as a process-unified signal via a V/I converter (209). This eliminates the need for tedious adjustments involving hardware such as a compensation capacitor in order to compensate the floating capacitance in capacitances (C1, C2), which is unrelated to diaphragm displacement. Instead, adjustment (calibration) is simplified without decreasing measurement precision, in that a microprocessor (205), in an initial calibration mode, takes a plurality of known pressure differences and measures capacitances (C1, C2) using time constant measuring unit (202), A/D converter (203) and timer counter (206). This data, which is needed to determine the constants needed to perform correction on floating capacitance and detection of pressure, is stored in memory (204). In measurement mode, pressure difference is calculated by using the measured capacitances (C1, C2) and the constants stored in memory (204). The results are output by the converter via D/A converter (207) and V/I converter (209). <IMAGE></p> |
