US 7,532,420 B2
Master disk for magnetic transfer, magnetic recording medium and magnetic recording apparatus
Makoto Nagao, Odawara (Japan); Minoru Araki, Odawara (Japan); Satoshi Wakamatsu, Odawara (Japan); and Kenji Ichikawa, Odawara (Japan)
Assigned to FUJIFILM Corporation, Tokyo (Japan)
Filed on Dec. 21, 2005, as Appl. No. 11/312,556.
Claims priority of application No. 2005-012878 (JP), filed on Jan. 20, 2005.
Prior Publication US 2006/0158763 A1, Jul. 20, 2006
Int. Cl. G11B 5/86 (2006.01)
U.S. Cl. 360—17  [360/16; 360/18] 3 Claims
OG exemplary drawing
 
1. A method of designing a master disk for magnetic transfer which has a disk-like outer shape and in the surface of which a large number of fine magnetic layer patterns are formed, wherein outside diameter size d (mm) of the extreme outer circumference of the magnetic layer pattern and the master disk thickness t (mm) are in a relationship where a value of t depends upon a value of d,
wherein the value of t increases as the value of d increases, and
wherein a lower limit for a range values of t is 2.04×10−3×d+0.006 and an upper limit for the range is 8.15×10−3×d+0.024, so that the master disk thickness t is designed in accordance with the value of d.