| 摘要 |
PURPOSE:To detect the notch of a disc rapidly and accurately by a method wherin a curvature fluctuation on the circumference of a disc at a specified distance is pursued after along the periphery of the disc to detect a straight line part out of circular part. CONSTITUTION:A marking peripheral image element detector 7 detects an optional peripheral image element P0 out of peripheral image elements on the circumference of a disc 2. Next a peripheral equidistant image element detector 8 as a means to detect two peripheral image elements P1 and P2 at a specified distance (r) from the reference image element P0 outputs location data of said elements P1 and P2 from the reference image element P0. A straight line discriminator 9 calculates a supplementary angle delta met by segments P0-P1 and P0-P2 in terms of the location data on three image elements comprising the reference image element P0, said peripheral equidistant image elements P1 and P2 to output a true datum in case the image elements P0, P1 and P2 are on a straight line with the supplementary angle delta=0 while a final processor 10 discriminates the direction of a notch of the straight line part i.e. the attitude of the disc 2. When the datum is false, said output may be forward to a marking image element shifting processor 11 to set up a new marking image element for detecting a truly straight line part. |
