Frequency scanning capaciflector for capacitively determining the material properties
US5521515A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 17, 1995 |
| Grant date | May 28, 1996 |
| Priority date | — |
| Expiry date | Feb 17, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/2405
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A capaciflector sensor system scanned in frequency is used to detect the permittivity of the material of an object being sensed. A capaciflector sensor element, coupled to current-measuring voltage follower circuitry, is driven by a frequency swept oscillator and generates an output which corresponds to capacity as a function of the input frequency. This swept frequency information is fed into apparatus e.g. a digital computer for comparing the shape of the capacitance vs. frequency curve against characteristic capacitor vs. frequency curves for a variety of different materials which are stored, for example, in a digital memory of the computer or a database. Using a technique of pattern matching, a determination is made as to the identification of the material. Also, when desirable, the distance between the sensor and the object can be determined.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.