A recorded tape has a tendency to transfer or print its magnetic pattern on adjacent layers when it is stored on a reel. This phenomenon is called the accidental printing effect, and a theoretical investigation has been made in 1953 by W.K. Westmijze, and further experimental work has not been reported.
In this article, the analysis of the accidental printing was made by establishing the following characteristics; the volume of magnetic particles, the coercive force of magnetic powder γ-Fe₂O₃ in which a small amount of cobalt is substituted, and the effect of temperature. Following results were obtained.
(1) The influence of particle size on printing effect was investigated. Sixteen samples of cubical Co-substituted γ-Fe₂O₃ were used to prepare the magnetic tapes. The increase of particle size from 0.046μ to 0.10μ in mean diameter resulted in the increase of printing effect.
(2) The influence of Hc of γ-Fe₂O₃ on printing effect was studied. The increase in the coercive force of about 10 Oe resulted in the increase in the printing effect by 0.6dB.
(3) The effect of temperature on the accidental printing was studied. It was indicated over the range of 10°C-65°C that the printing effect was reduced as the temperature was raised.