Blood fractionation apparatus having collection rate display system

摘要

An apparatus for separating and collecting plasma from whole blood includes a collection rate monitoring system which provides a digital display of the rate of plasma collection per minute. A transducer circuit within the system develops an electrical signal frequency-dependent on the weight of the collected plasma. The frequency of this signal over a present measurement interval is periodically compared with the frequency of the signal over a preceding measurement interval to develop a signal indicative of the volume of plasma collected during the interval. This signal is combined in a shift register with signals developed over a plurality of immediately preceding measurement intervals, which, taken with the present interval, comprise a one minute period, to develop at the end of each interval an output signal indicative of the total units of plasma collected over the previous minute. A display counter responsive to each output of the shift register produces a digital display of collected volume units per minute. In the illustrated embodiment, each measurement interval is one second, and the present increment and fifty-nine immediately preceding increments are combined to obtain a readout in units per minute.