US 12,293,780 B2
Magnetic recording medium having a particular specific surface area, magnetic recording and reproducing apparatus, and magnetic recording medium cartridge
Masaru Terakawa, Tokyo (JP); and Minoru Yamaga, Tokyo (JP)
Assigned to Sony Group Corporation, Tokyo (JP)
Appl. No. 17/760,571
Filed by Sony Group Corporation, Tokyo (JP)
PCT Filed Oct. 31, 2019, PCT No. PCT/JP2019/042752
§ 371(c)(1), (2) Date Mar. 15, 2022,
PCT Pub. No. WO2021/059542, PCT Pub. Date Apr. 1, 2021.
Claims priority of application No. 2019-176039 (JP), filed on Sep. 26, 2019.
Prior Publication US 2022/0399039 A1, Dec. 15, 2022
Int. Cl. G11B 5/78 (2006.01); G11B 5/592 (2006.01); G11B 5/706 (2006.01); G11B 5/714 (2006.01); G11B 5/72 (2006.01)
CPC G11B 5/70678 (2013.01) [G11B 5/5928 (2013.01); G11B 5/714 (2013.01); G11B 5/72 (2013.01); G11B 5/78 (2013.01)] 21 Claims
OG exemplary drawing
 
1. A magnetic recording medium having a tape shape, the magnetic recording medium comprising:
a base containing polyester as a main constituent; and
a magnetic layer provided on the base, including a plurality of magnetic powders, and configured to record a data signal, wherein
an average thickness of the magnetic recording medium is 5.6 μm or less,
an average thickness of the base is 4.2 μm or less,
an average thickness of the magnetic layer is 90 nm or less,
an average aspect ratio of the magnetic powders is 1.0 or greater and 3.0 or less,
a coercivity in a perpendicular direction is 3000 oersted or less,
a rate of a coercivity in a longitudinal direction to a coercivity in a perpendicular direction is 0.8 or less,
the magnetic layer includes a lubricant, and
an entire BET specific surface area of the magnetic recording medium from which the lubricant has been removed is 2.5 m2/g or greater.