| 摘要 |
<p>1472185 Liquid detector; bubble density measurement HECTRONIC AG 21 May 1974 [22 May 1973] 22512/74 Heading G1A Apparatus for detecting the presence of a liquid medium comprises a light source 4, a photoelectric detector 14 and at least one member 3 pervious to light rays, the arrangement being such that, in the absence of liquid, light from the source reaches the detector via path 9 passing outside pervious member 3 and in the presence of liquid, light does not reach the detector (path 9a). Preferably the detector is also associated with a light pervious member 13. As described, source 4 is a LED and detector 14a phototransistor. The pervious member has a refractive index of about 1À5, may be inorganic or organic glass, (e.g. acrylic), and may be of spherical or cylindrical section. Opaque sheet 22 prevents direct transmission between source and detector. The system only operates correctly when the liquid is bubble free as bubbles reflect, refract or diffract light, that would otherwise miss the detector to the detector and produce output pulses. A rough measure of bubble concentration can be determined from the frequency of these pulses. In an alternative embodiment, the source is placed behind a block of the light pervious material in one face of the vessel for the liquid and the detector is placed behind a sheet of glass in an adjacent face.</p> |
