US 12,243,569 B2
Magnetic recording medium and cartridge
Noboru Sekiguchi, Tokyo (JP); Yuuko Kamoshita, Tokyo (JP); and Minoru Yamaga, Tokyo (JP)
Assigned to Sony Group Corporation, Tokyo (JP)
Filed by Sony Group Corporation, Tokyo (JP)
Filed on Jun. 28, 2023, as Appl. No. 18/215,392.
Application 18/215,392 is a continuation of application No. 17/790,298, granted, now 11,854,585, previously published as PCT/JP2021/001664, filed on Jan. 19, 2021.
Claims priority of application No. 2020-007936 (JP), filed on Jan. 21, 2020.
Prior Publication US 2023/0368814 A1, Nov. 16, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. G11B 5/71 (2006.01); G11B 5/592 (2006.01); G11B 5/706 (2006.01); G11B 5/78 (2006.01)
CPC G11B 5/71 (2013.01) [G11B 5/5928 (2013.01); G11B 5/70678 (2013.01); G11B 5/78 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A magnetic recording medium comprising:
a substrate;
an underlayer disposed on the substrate; and
a magnetic layer disposed on the underlayer,
wherein the magnetic layer has a surface having an uneven shape,
wherein a height range ΔH obtained from a statistical information of a height of the uneven shape is in a range of 4.00 nm≤ΔH≤10.00 nm,
wherein a gradient range ΔA obtained from a statistical information of a gradient of the uneven shape is in a range of 2.50 degrees≤ΔA,
wherein an average thickness of the magnetic recording medium is 5.3 μm or less, and
wherein the substrate includes a polyester.