High-Density Recording Characteristics of Obliquely Oriented Particulate Magnetic Tapes by Removal of Disoriented Surface Layer
In order to achieve high recording densities, wide bandwidth and high output, a magnetic tape should have a high Bs, perpendicular orientation, a smooth surface, good head contact, and a small longitudinal component. By using a "LIPS" orienting process which produces media with a longitudinally oriented inside layer and a perpendicular oriented surface layer, we have fabricated obliquely oriented magnetic films based on acicular metal particles; of these, tape oriented at 45° had the widest-bandwidth characteristics. But a significant improvement in output was not obtained because of the existence of disoriented particles in the surface layer, resulting from calendering treatment. We tried to remove this surface layer using polishing sheets. An obliquely oriented (45°) tape exhibited an improvement in short-wavelength output (by 10 dB at 0.3 ¿m) after the thickness of the disoriented layer was reduced by 0.12 ¿m.
Analysis due to vector magnetic field for recording characteristic of metal evaporated tape
Metal-evaporated tape (ME tape) is one of the most promising materials for high-density magnetic recording. In a previous study, we reported that the recording characteristics of ME tape are directly affected by the columnar microstructure of the magnetic layer (Co-Ni-O magnetic film). In this study, we have conducted the theoretical analysis of the effects of both head motion and the vector magnetic field H θ , which is essentially parallel to the columnar longitudinal axis. The results of this analysis offer an effective explanation of the recording characteristics of ME tape.
A perpendicular orientation of a coated particulate medium by an AC-demagnetization process
A new perpendicular magnetic orientation method for coated particulate medium has been studied in order to resolve two problems : "self-demagnetization accompanying re-disorientation" of particles and "surface roughening" in conventional DC orientation method applied to coating a particulate medium in a low viscous state. These two phenomena are discussed in terms of a stabilization of magnetization energy in a perpendicular demagnetization field. AC demagnetization is used to erase residual magnetization just after AC magnetic orientation. For these two purposes a magnet is used which has a pair of pole pieces with graded edges and is operated at 50 Hz. CrO 2 particles in coated medium were perpendicularly oriented by this method. Achievement of the orientation is evident from magnetic measurements : Hc\perp=700 Oe, Hc\parallel=600 Oe, O. R. \perp=3.22 , O. R. \parallel =0.71, and from high