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US 5,210,769 AGranted
Liquid level measuring system
AssigneeThe Great American Company
InventorsWilliam W. Seidel, Lance C. Tagliapietra
Life of this patent
Estimating the term…
Abstract
A liquid level measuring and indicating system using a positive temperature coefficient wire as a sensor, a microprocessor based operating circuit, and an electronically controlled display device. With energy to operate the system being supplied by a battery, circuit includes energy conservation provisions.
Claims36
A system for measuring the level of a liquid in a container,
- a liquid level probe having,
- an insulating support member,
- a positive temperature coefficient conductor mounted on said insulating support member, and extending into the liquid, such that the portion of said positive temperature coefficient conductor immersed in the liquid is dependent on the level of the liquid in the container,
- a microprocessor for receiving an input signal from said liquid level probe,
- a display means for receiving an output signal from said microprocessor and displaying an indication of the liquid level as determined by said liquid level probe,
- a main power supply circuit energized by an unregulated power source, which provides a regulated power output,
- a constant current power supply circuit energized by said main power supply circuit for supplying a constant current to the positive temperature coefficient conductor, whereby the supply of current to said positive temperature coefficient conductor causes the voltage across said conductor to rise, the voltage rising at a rate which is dependent on the level of the liquid in the container, the rate of change of said voltage appearing across said conductor being processed by said microprocessor to supply a digital signal indicative of said liquid level to said display means which in response thereto provides a display indicative of the liquid level in the container.
4 more elements
A system for determining fluid level of liquid in a container comprising,
- a liquid level probe to interact with the fluid whose level is being measured having an insulating support member, a positive temperature coefficient conductor mounted on said insulating support member and extending into the liquid such that the portion of said positive temperature coefficient conductor immersed in liquid is dependent on the level of the liquid in the container,
- a microprocessor for receiving an input signal from said liquid level probe,
- a display means for receiving an output signal from said microprocessor and displaying an indication of the liquid level as determined by said liquid level probe,
- a main power supply circuit energized by an unregulated power source which provides regulated and unregulated power,
- a constant current power circuit energized by said unregulated power for supplying a constant current to the positive temperature coefficient conductor, whereby the supply of current to said positive temperature coefficient conductor causes the voltage appearing across said conductor to rise, the voltage rising at a rate which is dependent on the level of the liquid in the container, the rate of change of said voltage being processed by said microprocessor to supply a digital signal indicative of said liquid level to said display means which in response thereto provides a display indicative of the liquid level in the container.
2 more elements
Dependencies are inferred from the claim text.