US 12,094,506 B2
Magnetic-disk substrate and magnetic disk
Masanobu Itaya, Minami-Alps (JP); Kinobu Osakabe, Tokorozawa (JP); and Toshio Takizawa, Kai (JP)
Assigned to HOYA CORPORATION, Tokyo (JP); and HOYA GLASS DISK VIETNAM II LTD., Yen Province (VN)
Filed by Masanobu Itaya, Minami-Alps (JP); Kinobu Osakabe, Tokorozawa (JP); and Toshio Takizawa, Kai (JP)
Filed on Feb. 6, 2023, as Appl. No. 18/165,295.
Application 18/165,295 is a continuation of application No. 17/364,730, filed on Jun. 30, 2021, granted, now 11,587,585.
Application 17/364,730 is a continuation of application No. 16/368,046, filed on Mar. 28, 2019, granted, now 11,081,134, issued on Aug. 3, 2021.
Application 16/368,046 is a continuation of application No. 15/401,615, filed on Jan. 9, 2017, granted, now 10,283,156, issued on May 7, 2019.
Application 15/401,615 is a continuation of application No. 14/424,261, granted, now 9,564,166, issued on Feb. 7, 2017, previously published as PCT/JP2013/067944, filed on Jun. 28, 2013.
Claims priority of provisional application 61/694,521, filed on Aug. 29, 2012.
Prior Publication US 2023/0197111 A1, Jun. 22, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. G11B 5/82 (2006.01); G11B 5/73 (2006.01)
CPC G11B 5/82 (2013.01) [G11B 5/73921 (2019.05)] 20 Claims
OG exemplary drawing
 
1. A magnetic-disk substrate in which an average value of squares of inclinations is 0.0025 or less and a frequency at which squares of inclinations are 0.004 or more is 15% or less, in a case where samples of inclinations on a main surface are obtained at intervals of 10 nm,
the main surface is configured to receive at least a magnetic recording layer thereon,
the magnetic-disk substrate includes an outer circumferential end portion and an inner circumferential end portion, and
the magnetic-disk substrate is configured as a substrate of a magnetic disk for energy-assisted magnetic recording.