| 摘要 |
PURPOSE:To prevent a slide flaw from being formed on a tape surface by forming at least axial serrations on an external surface. CONSTITUTION:The serrations are so sectioned preferably that contact parts contacting a VTR tape are nearly linear, and the sectional shape is preferably a triangle, saw-tooth wave, or waveform as shown in a figure. Intervals of the serrations are at least about 200mum, preferably 200-500mum, and more preferably 200-250mum. The vertical angle of each serration is preferably about 90-130 deg.; when the vertical angle is <=90 deg., ridges of the serrations become easy to break off and when >=130 deg., they become close to planes to reduce the effect of the serrations. Similarly, flanks of each serration become close to planes when the intervals of the serrations are wide, so the effect is reduced. Normally, about 50, 80, or 100 serrations per inch are preferable in terms of both the manufacture and effect.
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