US 12,462,840 B2
Magnetic recording medium and cartridge
Noboru Sekiguchi, Tokyo (JP); Minoru Yamaga, Tokyo (JP); and Futoshi Sasaki, Tokyo (JP)
Assigned to SONY GROUP CORPORATION, Tokyo (JP)
Appl. No. 18/574,137
Filed by Sony Group Corporation, Tokyo (JP)
PCT Filed Mar. 31, 2022, PCT No. PCT/JP2022/016806
§ 371(c)(1), (2) Date Dec. 26, 2023,
PCT Pub. No. WO2023/002723, PCT Pub. Date Jan. 26, 2023.
Claims priority of application No. 2021-121070 (JP), filed on Jul. 21, 2021.
Prior Publication US 2024/0331727 A1, Oct. 3, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. G11B 5/733 (2006.01); G11B 5/706 (2006.01); G11B 5/708 (2006.01); G11B 5/714 (2006.01)
CPC G11B 5/733 (2013.01) [G11B 5/70678 (2013.01); G11B 5/7085 (2013.01); G11B 5/714 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A magnetic recording medium, the magnetic recording medium sequentially comprising a base, an underlayer, and a magnetic layer,
wherein the magnetic layer includes magnetic particles, first particles, and second particles having a Mohs hardness of 7.0 or more,
the magnetic layer has a concavoconvex shape on a magnetic surface,
the concavoconvex shape includes a first protrusion including the first particles and a second protrusion including the second particles,
a ratio H1/H2 of an average height H1 of the first protrusion and an average height H2 of the second protrusion satisfies H1/H2≤2.3,
a height range ΔH obtained from statistical information on a height of the concavoconvex shape satisfies 3.00 nm≤ΔH≤6.00 nm,
a gradient range ΔA obtained from statistical information on a gradient of the concavoconvex shape satisfies 4.00 degrees≤ΔA≤9.00 degrees,
the first particles include carbon-containing particles,
the second particles include non-magnetic particles, and
the magnetic recording medium is tape-shaped.