초록 ▼

A digital liquid level sensing apparatus for detecting variations in the dielectric of a substance being sensed, to thereby provide a signal indicative of the level of the liquid being sensed in relation to a known full level. The apparatus includes a reservoir having an output plate and an input pl

A digital liquid level sensing apparatus for detecting variations in the dielectric of a substance being sensed, to thereby provide a signal indicative of the level of the liquid being sensed in relation to a known full level. The apparatus includes a reservoir having an output plate and an input plate assembly associated therewith. The input plate assembly includes a plurality of independently electrically excitable input plates which transmit a signal through the liquid being sensed to the output plate. The signals from the output plate are processed and a determination is made as to the level of liquid in the reservoir relative to a known full level. If the input plate assembly is located against the exterior surface of one wall of the reservoir, then both of the interior and exterior portions of that particular wall should be devoid of any metallic surface. In an alternative embodiment, a discardable interior reservoir is provided which fits nestably within the reservoir of the sensor. The interior reservoir is particularly useful for measuring water-based bodily fluids such as urine, where it may be desirable to discard just the reservoir after use.

대표청구항 ▼

[ What is claimed is:] [1.] An apparatus for detecting a level of a liquid-based fluid, comprising:a capacitive element array including a plurality of independent input plates spaced longitudinally along an axis of measurement;a reservoir for supporting said capacitive element array thereon and a qu

[ What is claimed is:] [1.] An apparatus for detecting a level of a liquid-based fluid, comprising:a capacitive element array including a plurality of independent input plates spaced longitudinally along an axis of measurement;a reservoir for supporting said capacitive element array thereon and a quantity of said fluid therein, said reservoir having an interior wall and an exterior wall and having a metallized surface forming an output plate which substantially conforms to the cross-sectional shape of the reservoir, the output plate being spaced apart from said input plates and having a length sufficient to span all of said input plates;a controller for sequentially applying an input signal to each one of said input plates sequentially, one at a time, to thereby electrically excite each said input plate;a current-to-voltage amplifier responsive to said output plate for generating a voltage output signal representative of the current coupled onto said output plate each time one of said input plates is electrically excited by said controller;a peak detector responsive to said current-to-voltage amplifier for generating a peak voltage signal representative of the peak magnitude of the voltage signal from said current to voltage amplifier each time one of said input plates is electrically excited by said controller;memory for storing each one of said peak voltage signals associated with the current coupled onto said output plate for each input plate excited by said controller;said controller including a comparator for comparing said peak voltage signals generated from the excitation of said input plates, one of said input plates at a time in sequential fashion against a reference value, and for determining the difference in each of said peak voltage signals from said reference value, to thereby detect a change in a dielectric of said fluid adjacent any one of said input plates relative to said reference value, to thereby detect a liquid/air interface within said fluid reservoir from which a level of said fluid can be determined; andsaid controller further operating to determine the percentage of each said input plate that is disposed below said liquid/air interface such that a precise level of said fluid can be determined.