Patent ID: 6236324
Filing Date: 2001-05-22
Classification: G01F

Abstract:
A sensor for measuring a level of a liquid in a liquid containment space, comprising;(a) a sealable housing having an elastic plate as part of one surface of said housing;(b) a displacer attached to that surface of said plate that is on the outside of said housing, said displacer being sufficiently large to cause a change in the deformation of said plate when said displacer is immersed in said liquid;(c) at least one emitter of radiant energy in the infra-red portion of the spectrum and at least one sensor of radiant energy sensitive in the infra-red portion of the spectrum, said emitter and said sensor being located inside of said housing, said emitter being located on one side of a gap and said sensor being located on the other side of said gap, said emitter and said sensor positioned so that said energy from said emitter can transit said gap and enter the aperture of said sensor when there is no obstruction in said gap, said energy being of sufficient magnitude to cause a measurable change in the electrical output of said sensor, as compared to the electrical output of said sensor when said gap is obstructed;(d) at least one optical shutter, said shutter attached to the surface of said plate that is inside of said housing, said shutter being positioned in said gap so that said shutter does not block said energy when said displacer is not in contact with said liquid, said shutter size and shape being such that said shutter moves a distance sufficient to block said energy when the deformation of said plate is changed due to said displacer being immersed in said liquid.