| 摘要 |
A pressure-sensing capacitor and a method for trimming the capacitor is disclosed. The capacitor includes a pair of spaced flexible parallel quartz plates. A thin circular layer of conductive metal is formed on the opposing inner surfaces of the plates to define the electrodes of the capacitor. A glass frit sealing compound, forming a concentric ring about the conductive layers, is disposed between the plates to seal the evacuated space between the plates. The thickness of the ring is small enough so that the capacitance between the electrodes is higher by an unknown amount than the desired value of capacitance at every point in the range of variation of the value of pressure. The capacitor is trimmed by first measuring the capacitance value at zero pressure and also at a maximum pressure. The size and location of a path on one of the electrodes is computed from the measured capacitance values and the deflection characteristics of the plates. A point on the inner surface of one of the flexible plates moves a maximum perpendicular distance towards the other plate under pressure. That point defines a maximum deflection point along a deflection axis perpendicular to the inner surface at the maximum deflection point. Radiant energy in the form of a laser beam is applied to the electrode to cut through the electrode along the computed path which is closed on itself to define a disc eccentrically spaced a calculated distance from the deflection axis so that the value of capacitance at zero and the maximum pressure is substantially equal to the desired values.
|
