초록 ▼

A monitoring unit for remotely monitoring liquid levels in a container includes a common probe, a reference probe, and four sensing probes, each mounted to the container in electrical contact with liquid within the container. A liquid level sensing unit measures resistance between the common probe a

A monitoring unit for remotely monitoring liquid levels in a container includes a common probe, a reference probe, and four sensing probes, each mounted to the container in electrical contact with liquid within the container. A liquid level sensing unit measures resistance between the common probe and the reference probe and uses the measured resistance as a threshold to determine which of the sensing probes is in contact with liquid in the container. In this way, the sensing unit is made substantially independent of the resistivity of the liquid in the container. The sensing unit is connected to an evaluating unit by a single conductor, and the sensing unit draws a variable amount of current through the conductor in accordance with the number of sensing probes in contact with liquid in the container. The conductor thus supplies power to the sensing unit and also transmits information from the sensing unit to the evaluating unit. The evaluating unit includes a current-to-voltage converter which generates voltage proportional to the current drawn by the sensing unit. A display circuit displays an indication of the resulting voltage.

대표청구항 ▼

A liquid level sensing system for sensing the level of a liquid in a container, said system comprising: a set of sensing probes, a common probe, and a reference probe, each positioned at a respective level in electrical contact with a respective interior portion of the container; means for providing

A liquid level sensing system for sensing the level of a liquid in a container, said system comprising: a set of sensing probes, a common probe, and a reference probe, each positioned at a respective level in electrical contact with a respective interior portion of the container; means for providing a reference signal indicative of electrical resistance between the common probe and the reference probe through the liquid; means for providing a set of sensing signals, each indicative of electrical resistance between the common probe and a respective one of the sensing probes through the liquid; means for comparing the reference signal with each of the sensing signals and for providing a set of output signals indicative of the number of sensing signals which deviate from the reference signal by more than a selected amount.