Apparatus for detecting the physical properties of magnetic or electric conductive heat-responsive or deformable material using negative input impedance network
US3946307A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 23, 1974 |
| Grant date | Mar 23, 1976 |
| Priority date | — |
| Expiry date | Apr 23, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/82
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A measuring apparatus uses an impedance element whose impedance varies with the physical properties of an object consisting of magnetic or electric conductive, heat-responsive or deformable substance, under the condition where the impedance element is energized by a D.C. or A.C. voltage source of a predetermined level. Connected in parallel or series with the impedance element is a negative impedance network, with its input impedance set at a negative value, which comprises an amplifier and positive and negative feedback impedance networks each connected between the input and output terminals of the amplifier. At least either of the positive and negative feedback impedance networks is constituted by a low, high or band pass filter for eliminating an external noise component, whereby the measuring apparatus enables to detect the physical properties of the object with as high a sensitivity and accuracy as possible.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.