RECOGNITION OF GAP POSITION OF MAGNETIC HEAD

摘要

PURPOSE:To recognize a gap position of a magnetic head with high precision and at a high speed by a method wherein a set of points which have large differential values and of which the density levels of peripheral points exceed a threshold value is extracted from two-dimensional density image data and the gap position is calculated from data obtained by projecting this set of points in the direction of an azimuth angle of the magnetic head. CONSTITUTION:An image is subjected to photoelectric conversion by means of a solid- state image sensing element or a pickup tube type camera, and it is subjected further to A/D conversion and stored in a storage circuit. Next, a density level in the periphery of a pixie of the input data being the i-th fro the left and the j-th from above is determined. Then, the determined density level is compared with a threshold value to determine a value of secondary differential. A point 5 of a minimum value is found out in respect to each horizontal line 7 of an output image of the secondary differential. The coordinates of the minimum value thus obtained are projected in the direction of an azimuth angle. A distribution is computed for each of sections divided at equal intervals in parallel to the azimuth angle, so as to find out the section that contains the points 5 of the minimum value most. Thereby a gap part 1 is obtained as the minimum value of the secondary differential.