| 摘要 |
PURPOSE:To provide a rotary magnetic recording medium which permits easy discrimination of the front and rear from the appearance and eliminates the need for total inspection and to improve remarkaly the mass productivity of said medium by providing marker holes for discrimination of the front and rear consisting of at least one through-hole to said medium. CONSTITUTION:The rotary magnetic recording medium 20 is formed by forming the 1st and 2nd magnetic layers 11, 12, then molding the same into, for example, 88.9mm.phi disk shape by press blanking. An index hole 22 for monitoring the rotating condition during recording and reproducing is further formed thereto in the position apart by a prescribed distance from the central hole 21 in the radial direction. The marker hole 23 for discrimination of the front and rear having the diameter smaller than the diameter of the hole 22 is formed on the line running the hole 21 of the medium 20 and perpendicular to a reference line L so as to be positioned on the circumference inner than the circumference passing the position where the hole 22 is formed. The central hole 21, the index hole 22 and the marker hole 23 are simultaneously formed in the stage of blanking a substrate 10 to the disk shape.
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