Solid state fluid level sensor
First Claim
1. A method of manufacturing a solid state fluid level sensor for activating a pump, comprising the steps of:
- disposing a first electrode and a second electrode on a dielectric substrate;
disposing a current switching device and a first differential sensing circuit on the dielectric substrate;
electrically coupling the first and second electrodes to the current switching device and the differential sensing circuit to form a printed wiring board assembly, the first and second electrodes being configured to apply common mode signals to inputs of the first differential sensing circuit;
providing a housing that forms a fluid-proof cavity that is adapted to be submerged in a fluid whose level is to be detected;
disposing the printed wiring board assembly in the housing; and
sealing the printed wiring board assembly within the housing.
2 Assignments
0 Petitions
Accused Products
Abstract
A sensor system for sensing liquid level in a bilge, for use in automatic bilge pump actuation. First and second field effect sensors are potted or sealed within a container or the bilge wall and are aligned in a vertical array and each comprise a substantially planar pattern of “electrodes” or conductive traces disposed on a printed circuit board (PCB) along with integrated circuits used to create a loop or arc-shaped electric field. As bilge liquid rises to the proximity or level of the field effect sensors, a change in the arc-shaped electric field is sensed and, in response, a bilge pump is automatically actuated to pump liquid out of the bilge. Optionally, the pump control can be programmed by use of a microprocessor to permit control of on-off timing and prevent undesirable effects of “sloshing.”
42 Citations
19 Claims
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1. A method of manufacturing a solid state fluid level sensor for activating a pump, comprising the steps of:
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disposing a first electrode and a second electrode on a dielectric substrate; disposing a current switching device and a first differential sensing circuit on the dielectric substrate; electrically coupling the first and second electrodes to the current switching device and the differential sensing circuit to form a printed wiring board assembly, the first and second electrodes being configured to apply common mode signals to inputs of the first differential sensing circuit; providing a housing that forms a fluid-proof cavity that is adapted to be submerged in a fluid whose level is to be detected; disposing the printed wiring board assembly in the housing; and sealing the printed wiring board assembly within the housing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of manufacturing a solid state fluid level sensor for activating a pump, comprising the steps of:
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providing a dielectric substrate having a front surface opposite a back surface; disposing a first electrode pattern and a second electrode pattern on the back surface of the dielectric substrate, each of said first and second electrode patterns being configured to detect fluid contact with the front surface of the dielectric substrate and comprising a center electrode and an outer electrode, the outer electrode being in a spaced and substantially surrounding relationship to said center electrode; disposing a low impedance, active electrical component on the back surface of the dielectric substrate immediately adjacent to said first and second electrode patterns; and electrically coupling the first and second electrode patterns to the low impedance, active electrical component to form a printed wiring board assembly on the back surface of the dielectric substrate, wherein the printed wiring board assembly will activate the pump when fluid contact is detected at the front surface of the dielectric substrate. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification