Electro-optical liquid level indicator

Abstract

A liquid level indicator consisting of a transparent rod within which is embedded a plurality of infrared emitters and photosensors. The infrared emitters and photosensors are mounted to a substrate which places the emitters and sensors in such a geometry as to cause total internal reflection off the transparent rod surface when an emitter-sensor pair is above the liquid level and to minimize internal reflection when an emitter-sensor pair is immersed in the liquid. The emitters are activated by electric current via conductive paths which are part of the supporting substrate. The sensors provide electric currents to an external readout device to indicate the absence or presence of liquid between emitter-sensor pairs. The liquid level indicator is made relatively insensitive to ambient light by shading the sensors from all but the desired infrared rays from the emitters. The liquid level indicator is hinged to allow a given length indicator assembly to be used in a variety of container depths.

Dependencies are inferred from the claim text.