| 摘要 |
<P>PROBLEM TO BE SOLVED: To calculate an absolute position through a small amount of operation even when a false random code is used for an ABS pattern, and also to ensure the accuracy of the absolute position even when thickening or the like occurs in the ABS pattern. Ž<P>SOLUTION: This encoder is equipped with: a scale 102 which forms a contrast pattern by the ABS pattern 104 based on the false random code; an edge position detecting circuit 124 which binarizes a signal SA3 from a light receiving element 112 receiving the contrast pattern and determines a position where an absolute value after differentiation of a value of the binarized signal is maximum, for each section of the minimum line width P<SB>ABS</SB>of the ABS pattern 104;, a peak position detecting circuit 126 which determines a peak position PK from a histogram about the above position; a decoding circuit 128 which decodes the false random code, based on the binarized value; an ABS position detecting circuit 130 which calculates the absolute position by referring to a design value of the false random code; and a position data synthesizing circuit 132 which compensates the absolute position with the peak position PK. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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