Importance

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Abstract

Disclosed herein is a method and apparatus employing a D.C. drive motor and digital printhead for recording electrocardiographic data or other digital data on a chart at a constant time scale, regardless of temporary variations in the D.C. motor speed. A buffer memory stores sensed digital ECG data, and a data count register provides a count indicative of the amount of data stored. A pulse width register controls the width of long and short pulses generated by a motor driver for the selected paper speed. An experience count register has a count indicative of the relative number of long and short pulses generated. The original or current width of the pulses may be adjusted by the pulse width register, subject to the count of the experience count register, for controlling the speed of the D.C. drive motor. The motor speed is increased if the buffer memory is storing more than a preselected amount of data, and the motor speed is decreased if the buffer memory is storing less than a preselected amount of data. Means, including a tach count register, regulate the output of ECG data from the buffer memory to the digital printhead for recording at a rate proportional to the speed of the D.C. drive motor, to produce a constant time scale chart record of such data, regardless of temporary variations in the D.C. motor speed.

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First Claim