Circuit for detecting capacitance change in variable capacitance
US7071709B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 14, 2004 |
| Grant date | Jul 4, 2006 |
| Priority date | — |
| Expiry date | Dec 29, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01P15/125
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A capacitance of a capacitor member, which varies according to a dynamic force such as an acceleration force imposed on the capacitor member, is detected by a detecting circuit. The detecting circuit is composed of an operational amplifier and a switched capacitor circuit connected in parallel to each other. A reset time (t), during which a feedback capacitor in the switched capacitor circuit is discharged, is set to satisfy the following formula: t>(ΔC+m)/n, where ΔC is an initial capacitance of the capacitor member, and n and m are constant factors having values in certain ranges. By setting the reset time (t) according to the above formula, an amount of acceleration imposed on the capacitor member is accurately detected even when the capacitor member has a certain level of the initial capacitance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.