Patent ID: 7109512
Filing Date: 2006-09-19
Classification: G01F

Abstract:
1. A liquid level transducer, having a transparent body adapted for exposure to a liquid to be measured, the liquid level transducer comprising: an electrical circuit comprising: a light source for projecting radiant energy into the transparent body; a photosensor for detecting a level of the radiant energy emanating from the transparent body, the level of radiant energy being indicative of the presence or absence of liquid on the transparent body; a pulsing circuit portion connected to the light source for pulsing the light source between on and off conditions; a rectifier circuit portion connected to the photosensor for rectifying a signal from the photosensor, the rectified signal being proportional to the detected level of radiant energy; an integrator circuit portion connected to the rectifier circuit portion for temporarily storing the rectified signal; a comparator circuit portion connected to the integrator circuit portion for comparing the rectified signal with a predetermined value; and a load switch portion connected to the comparator circuit portion for switching an external load when the rectified signal is at least one of above and below the predetermined value; wherein the comparator circuit portion comprises first and second comparators, the first comparator being configured to output a high signal to the load switch portion when the rectified signal is above the predetermined value, the second comparator being configured to output a low signal to the load switch portion when the rectified signal is above the predetermined value.