US 12,073,861 B2
Magnetic recording medium
Minoru Yamaga, Miyagi (JP); and Futoshi Sasaki, Miyagi (JP)
Assigned to Sony Group Corporation, Tokyo (JP)
Filed by Sony Corporation, Tokyo (JP)
Filed on Mar. 20, 2023, as Appl. No. 18/123,510.
Application 18/123,510 is a continuation of application No. 16/649,400, granted, now 11,610,604, previously published as PCT/JP2019/038960, filed on Oct. 2, 2019.
Claims priority of application No. 2019-151590 (JP), filed on Aug. 21, 2019.
Prior Publication US 2023/0274764 A1, Aug. 31, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. G11B 5/706 (2006.01); G11B 5/592 (2006.01); G11B 5/71 (2006.01); G11B 5/714 (2006.01); G11B 5/73 (2006.01); G11B 5/735 (2006.01)
CPC G11B 5/70678 (2013.01) [G11B 5/5928 (2013.01); G11B 5/71 (2013.01); G11B 5/714 (2013.01); G11B 5/7358 (2019.05); G11B 5/73927 (2019.05)] 19 Claims
OG exemplary drawing
 
1. A magnetic recording medium in a form of a tape, comprising:
a substrate;
a foundation layer provided on the substrate; and
a magnetic layer provided on the foundation layer and containing a magnetic powder, wherein
the magnetic recording medium contains a lubricant,
an average thickness of the magnetic recording medium is equal to or smaller than 5.6 μm, a plurality of recessed portions each having a depth corresponding to 20% to less than 100% of an average thickness of the magnetic layer is provided on a surface of the magnetic layer, and the number of the recessed portions per unit area of 1,600 μm2 of the surface of the magnetic layer is equal to or greater than 20 and equal to or smaller than 200, and
an amount of exudation of the lubricant per unit region of 12.5 μm×9.3 μm on the surface of the magnetic layer in a vacuum is equal to or greater than 3.0 μm2 and equal to or smaller than 6.5 μm,
wherein a squareness ratio is equal to or lower than 38% in a longitudinal direction of the tape.