Dialysis machine having enhanced D/A resolution

Abstract

A dialysis machine has control circuit which detects changes in input water temperature and compensates the water heater. The control circuit detects changes in the conductivity of the dialysate concentrate and compensates the concentrate pump. Changes in supply voltage are detected and the outputs of the several sensors and the inputs to the pumps and heater comensated. The control circuit periodically calibrates the blood leak detector. In each of the feedback loops which service the heater and each of the pumps, the control circuit varies both the loop response time and the loop gain to compensate for changes in the dialysate flow rate. The resolution of the D/A converters which drive the pumps are enhanced by the control circuit by time modulating the LSB of the respective digital drive value. If any of the several sensed operating conditions varies significantly from the expected value, the control circuit terminates dialysis.

Dependencies are inferred from the claim text.