초록 ▼

A digital liquid level sensing apparatus for detecting variations in the dielectric of a substance being sensed. The apparatus includes a capacitive element array including a plurality of individual (i.e., segmented) input plates positioned along an axis of measurement of a fluid to be detected. The

A digital liquid level sensing apparatus for detecting variations in the dielectric of a substance being sensed. The apparatus includes a capacitive element array including a plurality of individual (i.e., segmented) input plates positioned along an axis of measurement of a fluid to be detected. The array also includes a common output plate having a length sufficient to span the entire accumulated length of the input plates. A controller sequentially applies DC excitation pulses to the input plates which cause a series of output currents to be coupled onto the output plate. The output currents are input to a current-to-voltage amplifier which generates a series of corresponding analog output voltages. The analog output voltages are then input to a peak voltage detector circuit to generate a series of peak voltage signals representative of the magnitudes of the analog output voltages. The controller converts each of the peak voltage signals into a corresponding digital value and stores each of the digital values in an on-board memory. The controller then sequentially compares each of the values against at least one predetermined reference value indicative of an output produced by an input plate disposed in air until a predetermined difference is detected between the reference value and any one of the stored digital values. This indicates a predetermined difference in the dielectric, thus indicating that a corresponding input plate is at least partially submerged in fluid.

대표청구항 ▼

[ What is claimed:] [1.] Apparatus for determining and monitoring the position of a dielectric material relative to a reference point, comprising:a plurality of independent input elements arranged generally parallel to one another and in spaced apart relation to one another;a common receiver plate s

[ What is claimed:] [1.] Apparatus for determining and monitoring the position of a dielectric material relative to a reference point, comprising:a plurality of independent input elements arranged generally parallel to one another and in spaced apart relation to one another;a common receiver plate spaced apart but adjacent said input elements for receiving electrical output signals coupled thereonto such that said receiver plate, in cooperation with said input elements, forms a plurality of independent capacitors;a controller for applying an electrical signal to each said input element to sequentially electrically excite each of said input elements;said controller including:an amplifier for generating a voltage signal representative of each said electrical output signal;a peak detector for detecting a peak magnitude of each said voltage signal coupled onto said receiver plate as each of said input elements is electrically excited;a comparator for comparing said voltage signals against a reference value;said controller determining from said voltage signals which ones of said capacitors have experienced a change in capacitance and the relative percentage of coverage of each said capacitor by said dielectric material to make a determination of the position of said dielectric material within a predetermined area.