Patent ID: 6484564
Filing Date: 2002-11-26
Classification: G01M

Abstract:
A liquid leakage sensor having a white paper that becomes transparent when liquid is absorbed; a paper holder for holding said paper level, said paper holder being placed on a floor and having a bottom thereof forming a reflector; a case inserted into said holder and having a transparent or semi-transparent bottom plate; a light source for emitting light to said paper through said transparent or semi-transparent bottom plate; a photodetection means for detecting light reflected from said holder bottom; and a sensing means for detecting liquid leakage based on data from the photodetection means; said light source and photodetection means being integrally housed in said case, and said case and holder being disposed with a gap therebetween so that when leaked liquid contacts an edge of said paper the leaked liquid quickly permeates the paper;or a liquid leakage sensor having a white paper that becomes transparent when liquid is absorbed; a paper holder for holding said paper level, the bottom of the paper holder forming a reflector; a case inserted into said holder and having a transparent or semi-transparent bottom plate; a light source for emitting light; a first light transmitting means for guiding light emitted from said light source to said paper through the transparent or semi-transparent bottom plate of the case; a second light transmitting means for detecting and transmitting reflected light from the holder bottom; a photodetection means for detecting light from said second light transmitting means; and a sensing means for detecting liquid leakage based on data from the photodetection means; an end of said first light transmitting means and an end of said second light transmitting means forming an integrated light path housed inside said case, and said case and holder being disposed with a gap therebetween so that when leaked liquid contacts an edge of said paper the leaked liquid quickly permeates the paper; wherein said paper has a circular or noncircular shape; and an asymmetrical opening formed in a middle part of the paper except in a reflection area and outside edge part of the paper, said opening being asymmetrical to the reflection area so that a bubble is not held in the reflection area even when a large volume of liquid leaks at once, said reflection area being detected by the photodetection means.