Physical displacement sensing with differential capacitor
US4011500A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 16, 1974 |
| Grant date | Mar 8, 1977 |
| Priority date | — |
| Expiry date | Dec 16, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M1/60
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A device for measuring spatial displacement comprises two similar elementary capacitors of a differential capacitor and which share a common movable armature and the two capacitors are used to produce respective pulses whose lengths are compared to produce a third pulse whose length is proportional to the displacement of the armature. In a preferred embodiment, the capacitors are switched in alternation into an oscillating circuit and serve to determine the frequency of oscillation thereof and the time taken for a fixed number of oscillations to be produced with each capacitor switched in is measured to produce the first and second pulses. An adder/subtractor counter is provided which provides a fourth pulse whose length is equal to twice that of the first pulse and the fourth pulse is compared with a pulse whose length equals the sum of the first and second pulses to produce the third pulse.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.