Magnetic recording and reproducing method and magnetic recording medium employed for the same

• US 6,791,803 B2
• Filed: 08/15/2002
• Issued: 09/14/2004
• Est. Priority Date: 08/20/2001
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Yamazaki, Nobuo, Saito, Shinji, Noguchi, Hitoshi
• Primary Examiner(s): Resan, Stevan A.
• Application Number:
  US10/218,569
• Publication Number:
  US 20030128453A1
• Time in Patent Office: 761 Days
• Field of Search: 428/329, 428/694.BH, 360/313, 360/55
• US Class Current: 428/829
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/70678 Ferrites
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles
• CPC Class Codes: Y10T 428/257 Iron oxide or aluminum oxide

Abstract

Provided are a method of magnetic recording and reproducing capable of permitting high density recording on magnetic recording media even under the condition of high data transfer rates and yielding adequate recording and reproduction characteristics when an MR head is used in reproduction, and a magnetic recording medium capable of being used in this magnetic recording and reproducing method. The magnetic recording and reproducing method is a method for reproducing a signal magnetically recorded on a magnetic recording medium with a magnetoresistive (MR) head. The magnetic recording medium comprises a substantially nonmagnetic lower layer and a magnetic layer comprising a hexagonal ferrite ferromagnetic powder and a binder in this order on at least one side of a nonmagnetic support, in which said hexagonal ferrite ferromagnetic powder has a mean plate diameter ranging from 15 to 40 nm and a mean plate thickness ranging from 4 to 15 nm, and said magnetic layer has a coercive force Hc ranging from 143.3 to 318.4 kA/m, and said signal magnetically recorded has a maximum recording frequency ranging from 10 to 80 MHz.

Claims

1. A magnetic recording and reproducing method for reproducing a signal magnetically recorded on a magnetic recording medium with a magnetoresistive (MR) head, wherein

said magnetic recording medium comprises a substantially nonmagnetic lower layer and a magnetic layer comprising a hexagonal ferrite ferromagnetic powder and a binder in this order on at least one side of a nonmagnetic support, in which said hexagonal ferrite ferromagnetic powder has a mean plate diameter ranging from 15 to 40 nm and a mean plate thickness ranging from 4 to 15 nm, and said magnetic layer has a coercive force Hc ranging from 143.3 to 318.4 kA/m, and

said signal magnetically recorded has a maximum recording frequency ranging from 40 50 to 80 MHz.

2. The magnetic recording and reproducing method according to claim 1, wherein said hexagonal ferrite ferromagnetic powder has a mean plate diameter ranging from 20 to 35 nm and a mean plate thickness ranging from 7 to 12 nm.

3. The magnetic recording and reproducing method according to claim 1, wherein said magnetic layer has a coercive force Hc ranging from 159.2 to 278.6 kA/m.

4. The magnetic recording and reproducing method according to claim 1, wherein said magnetic recording medium is a tape-shaped magnetic recording medium and said magnetic layer comprising a hexagonal ferrite ferromagnetic powder has a squareness ranging from 0.6 to 0.9.

5. The magnetic recording and reproducing method according to claim 1, wherein said magnetic recording medium is a disk-shaped magnetic recording medium and said magnetic layer comprising a hexagonal ferrite ferromagnetic powder has a squareness ranging from 0.45 to 0.65.

6. The magnetic recording and reproducing method according to claim 1, wherein said signal magnetically recorded has a maximum recording frequency ranging from 50 to 60 MHz.