Patent ID: 7341798
Filing Date: 2008-03-11
Classification: G11B

Abstract:
1. A magnetic tape medium for recording and reproducing data in the longitudinal direction comprising: a non-magnetic substrate; a first metal layer formed directly on a first surface of the non-magnetic substrate; a first magnetic layer formed on the first metal layer; a second magnetic layer formed on the first magnetic layer, the second magnetic layer including ferromagnetic powder dispersed in a binding agent and having a thickness of 0.3 μm or smaller; a second metal layer formed directly on a second surface of the non-magnetic substrate opposite the first surface of the non-magnetic substrate; a back layer formed on the second metal layer, the back layer including plate shaped or acicular shaped inorganic powder dispersed in a second binding agent and having a thickness of 0.1 to 1.5 μm, wherein a servo signal for a tracking control being recorded on at least one of the second magnetic layer and the back layer, a track density in the direction of width being 50 lines/mm or more, an off-track margin A equal to ((recording track width)−(reproducing track width))/2 being 5 μm or smaller, and a variation that is permitted at maximum as a dimensional variation in the direction of width due to environmental factors being small as low as 0.10% or less, and wherein the first metal layer and the second metal layer are made of a metallic material selected from metal, semimetal, alloy, and oxides and compounds of them.