Digital eddy current apparatus for generating metallurgical signatures and monitoring metallurgical contents of an electrically conductive material
US4230987A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 26, 1979 |
| Grant date | Oct 28, 1980 |
| Priority date | — |
| Expiry date | Feb 26, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/72
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The apparatus comprises a parallel coil and a capacitance, the coil having an air gap in which an unknown specimen is inserted, a source of alternating voltage applied to the coil-capacitance combination, scanning means for automatically varying the value of the capacitance in steps, thus varying the phase of the voltage across the coil, means for digitizing the phase of the voltage corresponding to each capacitance value, a memory in which those digitized phase values are stored, a reference memory containing digitized phase values for known specimens, and means for comparing the digitized phase values of the unknown specimen with those of known specimens. A digital tolerance control circuit is also provided which accommodates deviations between the reference and the known phase values, up to predetermined amounts, and means are provided for displaying the generic name or grade of the stored phase values which match the phase values of the unknown specimen.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.