| 摘要 |
PURPOSE:To keep prevent cracks on a ferromagnetic thin film a tape at a long life, by keeping a value obtained by subtracting a thermal expansion factor of a magnetic tape having a ferromagnetic thin film from a thermal expansion factor of a reel or a hub of a magnetic tape cassette, to a specifica value or over. CONSTITUTION:The value obtained by subtracting the thermal expansion factor of the magnetic tape from that of the reel or the hum of the magnetic tape cassette is set to 2X10<-5>/ deg.C or below. In the thin magnetic tape vapor-depositing Fe, Co, Ni, their alloys, or oxides, for example, a polyester film-based tape, the thermal expansion factor is 2.0X10<-5>/ deg.C. While that of titanium is 0.9X10<-5>/ deg.C and that of nylon is 10X10<-5>/ deg.C. In forming the reel and hub with titanium having less thermal expansion factor difference, the crack on the magnetic layer because of expanded reel or hub at high temperatures and the deformation of the magnetic layer because of the background layer of the tape pressed strongly against the magnetic layer resulting in deteriorating the S/N are prevented. |
