Effects of Magnetic Head Wear on Envelope

The signal envelope reproduced by a VCR head varies depending on the combination of the magnetic head contour shape and the tape stiffness, and particularly with low-stiffness tapes which result in a damped envelope. The shapes of head sliding surfaces were measured by the interference ring method using spline interpolation. Changes in the head shape due to wear resulted in various patterns depending on the head construction. The dependence of reproduced envelopes on the head shape and tape tension was studied in connection with the tape stiffness. The reproduced envelope was found to decrease with increasing radius of curvature of the head surface in the width direction. The envelope can be improved by choosing the best gap position on the head contour for different head constructions, and by decreasing the tape tension and head protrusion.