JPS6432424A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the accuracy of an inline monitor for the thickness of a protective film by recording signals of the same wavelength on a metallic medium on which the protective film is formed and a metallic medium on which the protective film is not formed and comparing the reproduced outputs of both. CONSTITUTION:This recording and reproducing roller is constituted of cylinder roller parts 11a, 11b which have magnetic heads 13a, 13b for recording and magnetic heads 14a, 14b for reproducing and rotate at a high speed and a roller part 12. The magnetic heads 13a, 13b for recording record the track-like signals on the surface of the recording layer of the metallic medium wound on the outside circumference of the recording and reproducing roller. The magnetic heads 14a, 14b for reproducing installed to slide on the same tracks reproduce these signals. The outputs detected by the recording and reproducing roller on which the metallic medium formed with a diamond-like carbon film are smaller by as much as the spacing loss component corresponding to the thickness of the diamond-like carbon film than the outputs detected by the recording and reproducing roll wound with the metallic medium on which the diamond- like carbon film is not formed. The accurate inline monitor of the thickness of the protective film is thereby executed.