PRODUCING DEVICE OF STANDARDIZED TAPE FOR CONTROL OF DROP-OUT CORRECTION LEVEL

摘要

PURPOSE:To attain production of a tape through a simple VTR for reduction of cost by controlling continuously the degree of demagentization with detection of the level of the drop-out obtained from a demagnetizing means. CONSTITUTION:A magnetic tape 12 recorded previously by an optimum recording current travels through an erasion fixed head 13 and undergoes the normal reproduction via a video head drum 11. The RF signal obtained from a video head attached to the drum 11 is amplified by a video head amplifier 14 and turned into a waveform (a). This waveform (a) undergoes a shaping process through a DO level detecting circuit 15 to be turned into a waveform (b) and produces a waveform (c) in the form of the DC voltage showing the drop-out degree of the DO. This DC voltage drives an erasion current control circuit 16, and a current is supplied to an erasion fixed head 13. Thus the demagnetization is carried out in the lengthwise direction of the tape running through the gap part of the head 13. Then the DO shown by the waveform (a) is produced. Thus the DO produced by demagnetization are detected simultaneously and the erasion current is controlled so that the level of the DO is always constant against the set value.