Importance

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Abstract

Control apparatus for a stepping motor driving a peristaltic pump comprises a presettable downcounter for supplying drive pulses to the stepping motor at different repetition rates so as to regulate the speed of rotation of the motor, processing means for controlling the downcounter so that the motor is normally operated to drive the pump at a predetermined pumping rate, and a sensor for detecting indexing marks at spaced positions about the pump head, the processing means being responsive to the sensor detecting the index marks to alter the count in the downcounter so as to increase the motor speed for a predetermined number of motor steps upon detection of each index mark. After the predetermined number of steps at increased speed, the processing means resets the downcounter to its normal setting, so that the motor operates at the required pumping rate for a further predetermined number of motor steps and until detection of the next successive index mark of the head. Hence, the drive motor rotates or skips more rapidly during alternate periods corresponding to dwell periods of the peristaltic pump when reduced or no fluid flow would normally occur and, consequently, the pump delivers fluid at a more constant flow rate.

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First Claim