Tape speed and tension control system for a magnetic tape cassette apparatus

摘要

A digital tape cassette apparatus having a speed sensing roller in frictional contact with the magnetic tape within a cassette housing at a point intermediate the magnetic head and that one of the cassette hubs operating as the takeup hub during forward tape transportation. Utilizing a tape speed signal generated by a speed sensor driven by the speed sensing roller, a closed loop servomechanism controls a pair of drive motors coupled directly to the respective cassette hubs to afford constant tape speed. The servomechanism is associated with a tape tension control circuit whereby a supply side one of the drive motors during tape travel in either direction is energized to an extent increasing with the increase in the diameter of the tape reel on the takeup side hub, thereby affording constant tape tension. A reverse tape tension drop circuit is connected to the tape tension control circuit for making the tape tension less during reverse tape travel than during forward tape travel under the condition of the same tape reel diameter on the takeup side cassette hub, so that the tape tension at the magnetic tape is rendered approximately the same during forward and reverse tape travels despite the dynamically asymmetrical tape path due to the speed sensing roller in frictional engagement with the tape.