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US Patent numbers 5,406,843 and
it's continuations; 5,613,399,
6,125,696, and
6,138,508.
Availability
This patent, and it's continuations, are available for sale.
Key Benefits
- Capacitive Liquid Level Sensing Technology
- High Resolution
- Harsh Environments
Abstract
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.
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