| 摘要 |
PROBLEM TO BE SOLVED: To make it passable to display the parameter of a scan signal with high resolution and high accuracy, by making a particularly important parameter of the scan signal recognizable, and obtaining the scan signal of good quality with a simple means. SOLUTION: A measuring scale 1 having an incremental graduation 2 is scanned by a scanning head 3. Scanning elements F1, F2 of the scanning head 3 generate scan signals S1, S2 with a 90 deg. phase shift. The resolution of the scan signal S1, S2 is interpolated to a lower graduation unit so as to obtain better positional measurement value than a graduation cycle of the incremental graduation 2. For the interpolation of high accuracy, the scan signals S1, S2 are shifted correctly by 90 deg. and have a signal amplitude A as high as possible. Moreover, signal amplitudes A1, A2 of the scan signals hold S1=A1sinωt and S2=A2cosωt, respectively. The analog scan signals S1, S2 are fed to a control device 4, so that a parameter (phase position, amplitude) can be inspected particularly effectively by the control device 4.
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