公开(公告)号：US10607647B2

公开(公告)日：2020-03-31

申请号：US15611243

申请日：2017-06-01

Applicant: HOYA CORPORATION ,  HOYA LAMPHUN LTD.

Inventor： Toshio Takizawa ,  Kraisorn Phandon ,  Kenichi Nishimori

IPC: G11B5/73 ,  G11B5/82

Abstract: A magnetic disk substrate having a flat main surface, an end face, and a chamfered face formed between the main surface and the end face. The substrate has an offset portion, present on the main surface within a range of 92.0 to 97.0% in a radial direction from a center of the substrate. A distance from the center of the substrate to the end face of the substrate in a radial direction is 100%, the offset portion being raised or lowered with respect to a virtual straight line connecting two points on the main surface, set at positions of 92.0% and 97.0%. A maximum distance from the virtual straight line to the offset portion in a direction perpendicular to the virtual straight line is a “maximum offset value.”