Impedance detection apparatus and method of physical variable
US6373264B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 8, 1999 |
| Grant date | Apr 16, 2002 |
| Priority date | — |
| Expiry date | Oct 8, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R5/04
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for detecting an impedance variable in response to a sensed physical amount of a sensor is provided which comprises an impedance-frequency conversion unit and a counter. The impedance-frequency conversion unit converts the sensor impedance to an oscillation signal a frequency of which corresponds to the sensor impedance. The impedance-frequency conversion unit comprises an impedance-voltage converter for providing a voltage corresponding to the sensor impedance, and a Wien bridge oscillator including an element an impedance of which varies in response to the voltage from the impedance-voltage converter, for generating the oscillation signal. The Wien bridge oscillator is capable of generating a square wave signal as the oscillation signal. The counter counts the number of waves (or wave number) of the oscillation signal in a predetermined time period to output a count value which can be handled as a digital signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.