Patent ID: 6485980
Filing Date: 2002-11-26
Classification: G01N,Y10T

Abstract:
An apparatus for controlling a stream of liquid packages, each liquid package comprising a plurality of liquid and air segments, the liquid packages being formed in one or more cycles of aspiration of liquid and air segments, each cycle beginning with the aspiration of a first air segment and a first liquid segment, the apparatus comprising:a fluid conduit into which the liquid and air segments aspirated in each of said cycles are inserted and in which the stream of liquid packages is repeatedly bi-directionally flowed in a forward and a reverse direction; a valve coupled to a first end of said fluid conduit; an air and liquid interface detector positioned along said fluid conduit adjacent said valve; a detection apparatus positioned along said fluid conduit for measuring a reaction that occurs in said stream of liquid packages as they flow by said detection apparatus in said forward and reverse directions; means for stopping said flow of said stream of liquid packages in said reverse direction; and a feedback controller comprising a feedback loop for adjusting the time of stopping the flow of said stream of liquid packages at a point in time calculated from when said air and liquid interface detector detects an interface between the first air segment and the first liquid segment most recently inserted into said fluid conduit adjusted by a delay, said delay being normalized around a predetermined nominal center point delay.