Patent ID: 7136252

Claim:
A magnetic recording and reproducing apparatus comprising a magnetic recording medium having a data information recording portion and a servo information portion for tracking, and a magnetic head for detecting servo information of said servo information portion and recording and reproducing data information on and from said data information recording portion, wherein said servo information portion is formed by a convex pattern of a magnetic layer formed in a predetermined convex-concave pattern and a nonmagnetic material is filled inside a concave pattern, said servo information portion comprising a burst portion where burst signals for tracking are recorded, said burst portion is formed by disposing at predetermined positions magnetic layers in the form of convex portions where the burst signals are recorded, and when a length of said magnetic layer in the form of the convex portion in a track circumferential direction is given as L′ 1 , a length thereof in a track width direction (track radial direction) is given as W′ 1 , a whole thickness of said magnetic layer in a region of the convex portion is given as t, an interval in the track width direction (track radial direction) between said magnetic layers in the form of the convex portions adjacent to each other is given as W′ 2 , an interval thereof in the track circumferential direction is given as L′ 2 , a thickness of the magnetic layer remaining under a concave portion is given as δ, and a coercive force, a saturation magnetization, and a coercive force squareness ratio in a direction perpendicular to the film plane of said magnetic layer in the form of the convex portion are given as Hc, Ms, and S*, respectively, a specification of said burst portion is set so that said coercive force squareness ratio S* takes a value of 0.8 or more and a relationship of a first inequality is satisfied, said first inequality given as Hc · S * > Ms ( ⁢ 4 ⁢ arctan ⁢ L ′ ⁢ 1 ⁢ ⁢ W ′ ⁢ 1 t ⁢ L ′ ⁢ 1 2 + W ′ ⁢ 1 2 + t 2 - 4 ⁢ arctan ⁢ L ′ ⁢ 1 ⁢ ⁢ W ′ ⁢ 2 ( t - 2 ⁢ δ ) ⁢ L ′ ⁢ 1 2 + W ′ ⁢ 2 2 + t 2 + 4 ⁢ arctan ⁢ L ′ ⁢ 1 ⁢ ⁢ W ′ ⁢ 1 ( t - 2 ⁢ δ ) ⁢ L ′ ⁢ 1 2 + W ′ ⁢ 1 2 + ( t - 2 ⁢ δ ) 2 + 4 ⁢ arctan ⁢ L ′ ⁢ 1 ⁢ ( W ′ ⁢ 1 + 2 ⁢ W ′ ⁢ 2 ) ( t - 2 ⁢ δ ) ⁢ L ′ ⁢ 1 2 + ( W ′ ⁢ 1 + 2 ⁢ W ′ ⁢ 2 ) 2 + ( t - 2 ⁢ δ ) 2 - 4 ⁢ arctan ⁢ ( L ′ ⁢ 1 + 2 ⁢ L ′ ⁢ 2 ) ⁢ ( W ′ ⁢ 1 + 2 ⁢ W ′ ⁢ 2 ) ( t - 2 ⁢ δ ) ⁢ ( L ′ ⁢ 1 + 2 ⁢ L ′ ⁢ 2 ) 2 + ( W ′ ⁢ 1 + 2 ⁢ W ′ ⁢ 2 ) 2 + ( t - 2 ⁢ δ ) 2 + 4 ⁢ arctan ⁢ ( L ′ ⁢ 1 + 2 ⁢ L ′ ⁢ 2 ) ⁢ ( W ′ ⁢ 1 + 2 ⁢ W ′ ⁢ 2 ) t ⁢ ( L ′ ⁢ 1 + 2 ⁢ L ′ ⁢ 2 ) 2 + ( W ′ ⁢ 1 + 2 ⁢ W ′ ⁢ 2 ) 2 + t 2 ) .