Proximity sensor for level sensing
First Claim
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1. An apparatus for sensing the level of a substance contained in a tank having a bottom portion and a side wall portion, comprising:
- a first, thin planar electrode associated with said side wall portion;
a second, thin planar electrode associated with on said side wall portion;
said second electrode arranged on said side wall portion substantially above said first electrode with respect to said bottom portion;
said first electrode coupled to a first resistor and to a first input of a detection circuit;
said second electrode coupled to a second resistor and to a second input of a detection circuit;
a strobe line coupled to said first resistor and said second resistor;
wherein said detection circuit produces a low-level output when said fluid substantially covers neither said first nor said second electrode;
wherein said detection circuit produces a low-level output when said fluid substantially covers both said first and said second electrode;
wherein said detection circuit produces a high-level output when said fluid substantially covers one, but not both, of said first and said second electrodes.
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Abstract
A field effect sensor is adapted for use in sensing level of fluids and powders. The sensor uses elongated, parallel electrodes disposed on or within the side wall of a tank. The longitudinal axes of the electrodes are parallel to the surface of fluid or powder contained in the tank.
15 Citations
9 Claims
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1. An apparatus for sensing the level of a substance contained in a tank having a bottom portion and a side wall portion, comprising:
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a first, thin planar electrode associated with said side wall portion;
a second, thin planar electrode associated with on said side wall portion;
said second electrode arranged on said side wall portion substantially above said first electrode with respect to said bottom portion;
said first electrode coupled to a first resistor and to a first input of a detection circuit;
said second electrode coupled to a second resistor and to a second input of a detection circuit;
a strobe line coupled to said first resistor and said second resistor;
wherein said detection circuit produces a low-level output when said fluid substantially covers neither said first nor said second electrode;
wherein said detection circuit produces a low-level output when said fluid substantially covers both said first and said second electrode;
wherein said detection circuit produces a high-level output when said fluid substantially covers one, but not both, of said first and said second electrodes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification