Position detecting system

摘要

A position detecting system has the following steps of: detecting picture element information (E2) corresponding to patterns on a chip (10) illuminated; calculating threshold information (E3) representing a threshold level (S1, S3) to discriminate a pad pattern (11) from the patterns on the basis of the mean (eH) of a high level portion of the picture element information (E2) and the mean (eL) of low level portion thereof; and calculating a position of the pad pattern (11) from video information (E4) discriminated with respect to the threshold level (S1, S3) by comparing a level of the threshold information (E3) with a level of video information (E4) corresponding to the picture element information (E2) used to calculate the threshold information (E3).