Liquid level sensor and electrode assembly therefor
US3939360A · kind A · utility
Assignees
Inventor
Key dates
| Filing date | Jan 22, 1975 |
| Grant date | Feb 17, 1976 |
| Priority date | — |
| Expiry date | Jan 22, 1995 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/7306
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system for detecting the fluid level in an intravenous bottle wherein a disposable electrode assembly, consisting of a piece of tape having upper, middle and lower electrode strips, is adhered to the bottle and connected to sensing equipment. The upper strip is longer than the middle strip and the middle strip is longer than the lower strip, so that the capacity between the upper and middle strips (C.sub.1) is normally greater than that between the middle and lower strips (C.sub.2). The sensing equipment includes a bias capacity (C.sub.3) connected between the middle and lower strips so that C.sub.1 is less than C.sub.2 plus C.sub.3 except when the tape is on a bottle with the fluid level in the bottle above the top strip. Pulses having a gradually sloped leading edge and a steep trailing edge are fed to the centre strip. The received pulses at the top and bottom strips are differentiated and fed to the inputs of a differential amplifier which produces an output which changes in polarity when the fluid drops below the upper electrode strip. A delay circuit generates an alarm signal after the changed polarity output signal has persisted for a predetermined interval. If the tape fa…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.