Device and method for determining liquid-probe contact
US5866426A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 17, 1996 |
| Grant date | Feb 2, 1999 |
| Priority date | — |
| Expiry date | Dec 17, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T436/2575
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A sensor detects when a probe contacts liquid in a container due to a change in frequency of a probe oscillator. The sensor can have its output compared to a reference level to determine the presence or absence of liquid wherein the reference level is changed to follow the output of the detector. In one embodiment, it can be determined that liquid has been contacted when a count has been reached several times in a row (the count being a function of the probe output and changeable). In another embodiment of the invention, it can be determined that liquid has been contacted when a count has been reached within a certain threshold several times in a row, while still having the reference count change to follow the probe output (regardless of the threshold). A digital counter can be provided to determine the frequency of the probe oscillator. A reference counter can also be provided to tune the count (frequency) from the probe oscillator counter to thereby compensate for drift. And, the adjustable detection threshold permits control of the sensitivity by changing the parameters of the circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.