| 摘要 |
PROBLEM TO BE SOLVED: To realize low noise high output and high C/N by a method wherein the ratio between the maximum and minimum values of coercive force acquired when the magnetic field angleθimpressed longitudinally is varied within a specific angle range is specified to be at a specific value. SOLUTION: A chamber is exhausted at the pressure down to 3×10<-7> Torr and then a PET film 9.8μm thick is wound from the feeding side roll to the winding side roll at a rate of 25m/min so that the PET film may be irradiated with electron beams from two electron guns in output of 30kw and 25kw to evaporate a magnetic metal. Besides, in case of evaporating the magnetic metal particles, oxygen at 130 and 110sccm is fed from respective oxygen gas feeding nozzles. Thus, a magnetic tape for 8mm VTR having dual layer laminated magnetic films (upper and lower layer magnetic films 800Å, 1200Åthick respectively) can be formed. Through these procedures, the ratio between the maximum value Hcmax and the minimum value Hcmin of coercive force acquired when the impressed magnetic field angle of this magnetic tape is varied from 0 deg. to 180 deg. will become 4-6.
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