| 摘要 |
<p>PURPOSE:To increase the accuracy of measurement, by performing a compensation of the interpolated scales through an automatic detection of the vernier relation between a grid pattern and a sensor array based on the output waveform of the sensor array. CONSTITUTION:The output of sensor 21 that is supplied to the signal distributor 32 from an amplifier 26 is distributed into the signals of elements of both even- and odd-number orders, and the counting of counter 36 is stopped with the intersection where the positive phase shifts to the negative phase is detected through the comparator 35 via the envelope curve wave detectors 33 and 34. At the same time, the FF37 is set. The FF37 opens the gate 38 until the comparator detects intersection and sends consecutively the clock to the counter 39 from the oscillator 22. The outputs of counters 36 and 39 are applied to the converting circuit 40 to perform a compensation to the variation of projecting magnification ratio to the line sensor 21 of optical grid. Then the rough-read value signal sent from the counter 30 is received via the sample holding circuit 27 and others and then converted into an actual shift extent via the adder circuit 42 and multiplier circuit 41 to be displayed on a display device. In such way, the accuracy of measurement can be increased.</p> |
