High speed and highly stable motors are required for magnetic disk or LBP polygon mirror devices. To measure fluctuations in the rotational speed of the motor, an encoder is provided and measurements of period, phase difference, pulse width jitter, max., min. and average of the signal output from the encoder are made (see figure below). Usually, all these items can be measured by changing measuring functions of the Time Interval Analyzer. On a manufacturing line, it is necessary to shorten the measuring time. To do this, shape the waveform as shown below and measure pulse width only. This data can be transferred to a PC and converted to interval or pulse width using calculations.
*Period, pulse width and phase difference between A and B are calculated by the PC. Average, jitter, maximum and minimum values are also calculated based on the above results.
The Yokogawa Model TA320 provides the following solution for this application:
veform is shaped and pulse width is measured to shorten the measuring time, it can measure 8000 periods of encoder signal.
*Signal shaping circuit and analysis software are to be provided by customers.
The TA320 Time Interval Analyzer is an instrument which can measure the period, pulse width and time interval of a signal continuously at a maximum rate of 14 MS/s with a maximum resolution of 100 picoseconds. The large liquid crystal display panel is equipped with a touch-sensitive screen, enabling an intuitive, smooth operation in measurement and data analysis. A high screen-update rate allows the immediate display of analysis results.