Liquid level indicators
Abstract
Abstract A LIQUID LEVEL INDICATOR, PARTICULARLY SUITABLE AS A TIDE GAUGE, INDICATES THE MEAN LEVEL OF A LIQUID. A NUMBER OF SENSING ELEMENTS, E.G. CAPACTIVE ELECTRODES OR DONCUTIVITY SENSORS, SPACED VERTICALY, SENSE THE PRESENCE OR ABSNCE OF LIQUID AT EACH ELECTRODE AND GIVE SIGNALS WHICH MAY BE CONVERTED TO A BINARY DIGITAL NUMBER INDICATING THE INSTANTANEOUS LEVEL. THIS DIGITAL OUTPUT SIGNAL CONTROLS A SERIES OF AND GATES TO PASS PULSES WHICH, FOR EACH GATE, ARE AT A RATE CORRESPONDING TO THE SIGNIFICANCE OF THE APPROPRIATE DIGIT. THE PULSES ARE NON-COINCIDENT PULSES OBTAINED BY DIVIDING DOWN THE OUTPUT OF AN OSCILLATOR. THE TOTAL NUMBER OF PULSES FROM ALL THE GATES OVER A PREDETERMINED PERIOD IS FED TO A COUNTER WHICH INDICATES THE MEAN LEVEL OVER THAT PERIOD. BY USING PULSE TRAINS, THE LEVEL IS AVERAGED OVER A PERIOD OF TIME ENABLING THE MEAN LEVEL TO BE DETERMINED TO AN ACCURACY BETTER THAN THE ELECTRODE SPACING.
Inventors
- 👤 James Stewart Johnston
Bibliographic Details
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-01-04 | 1974-07-06 | 1975-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |