Abstract
Experiments were made to study the contact force and frictional force between the magnetic head and the magnetic tape in a two head helical scan type VTR. Both forces were directly measured in the experiment in which the head attached to spring plates contacts with the tape under the conditions of the rest and running at 0.19 m/s. The frictional force at higher speeds was measured by means of the deceleration of disk having heads due to friction. The tension of tape running around the cylinder was also studied in VTR. The frictional force increases linearly with the increase of tape tension and height of head protruded from the cylinder and is of order of 1 g. The friction is independent upon the frictional speed over the range of 0.19 to 11 m/s. It is concluded that the frictional force is directly proportional to the contact force and the coefficient of friction takes approximately the value of 0.22 in operation of VTR. The tape tension at the tape supplying side of the cylinder in VTR is about three times that at the winding side. The increase of tension is mainly due to the friction of tape sliding on the cylinder and decreases as the protruding height of head increases.
