| 摘要 |
PURPOSE:To improve the reading/writing accuracy of information on an optical memory card by providing plural position recognizing patterns on the memory card and measuring the displacement of these patterns with high accuracy by means of a picture processing to detect the position of the memory card with high accuracy. CONSTITUTION:In a displacement value calculating process 40, a recognizing pattern having no loading error is photographed and registered to a reference recognizing pattern film 35. Thus a point where i=1 and j=1 calculated in a processing 30 are satisfied shows zero in terms of the loading position error, where (i) shows a segmentation start line of a partial picture set on the basis of read picture and (j) shows a segmentation start pixel respectively. Therefore i=-DELTAx and j=DELTAy (DELTAx, DELTAy>=0) are satisfied with the position of a recognizing pattern 100 formed on an optical memory card 90 having a loading error in comparison with a recognizing pattern 80 on an optical memory card 70. In other words, DELTAx and DELTAy show the displacement values against the reference position. In a correction value calculating process these calculated displacement values DELTAx and DELTAy are read out and converted into the variates serving as the input of a driving system of a beam scanning/photodetecting device.
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