| 摘要 |
PURPOSE:To enhance temp. stability, by alternately connecting detection capacity and reference capacity to the same converter circuit through a change-over circuit to convert the respective capacities to oscillation frequencies and detecting the ratio of said oscillation frequencies. CONSTITUTION:An alumina diaphragm 1 having a disk-shaped common electrode 6 mounted to the rear surface thereof and an alumina base stand 3 equipped with a disk-shaped detection electrode 7 and an annular reference electrode 8 are provided to a wt. detection element and the peripheral parts of both of them are fixed by a glass adhesive layer 5 to respectively form detection capacity CW between electrodes 7, 6 and reference capacity CR between electrodes 8, 6. The capacities CW, CR are alternately connected to a converter circuit through a change-over circuit SW to be respectively converted to detection frequency and reference frequency and the ratio of both frequencies is calculated by a microcomputer. Therefore, temp. stability can be made excellent regardless of the temp. characteristic of the converter circuit.
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