| 摘要 |
A generated signal is passed through an elongated signal conveying element positioned preferably perpendicular to the surface of a fluid the level of which is to be measured. The signal is directed from the signal conveying element to a detector element which senses the signal output from the signal conveying element. The signal output detected varies linearly with the depth of immersion of the signal conveying element into the fluid. In one embodiment, the signal conveying element is a capacitive probe comprising two plates or wires, one of which is grounded to the fluid into which the two plates or wires are immersed. Proper selection of accompanying circuitry results in detected signal changes which vary linearly with immersion changes. A second embodiment employs an electromagnetic wave, e.g. light, signal which passes through a light pipe signal conveying element. By nearly matching the light pipe index of refraction with that of the fluid, a predetermined percentage of the wave is lost into the fluid. The portion of light sensed at a detector, which is located where the unrefracted light exits, is simply converted to a linear output which corresponds to the depth the light pipe signal conveying element is immersed into the fluid.
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