Tape transport control unit

A tape transport control unit in a magnetic tape apparatus in which a supply reel and a take-up reel are driven by separate motors and a magnetic tape on the supply reel is transported from the supply reel to the take-up reel past a read/write head disposed between the reels without routing a buffer through a substantially constant length path and a reel status amount representing a total amount of the tape on the reel varies from time to time, comprising:

• reel status amount sensing means for sensing the reel status amount of tape rool radii and reel moments of each of said supply reel and said tape-up reel;
• means contacting said tape for detecting a tape tension between said supply reel and said take-up reel;
• reel drive means for comparing a predetermined target signal of each of said supply reel and said take-up reel with a feedback signal obtained by adjusting a signal from said reel status amount sensing means by means of a feedback compensation circuit, and for driving reel drive motors separately connected to each reel on the basis of the compared signal;
• arithmetic and storage means for calculating and storing gain values and feedback constants of said reel drive means which are compensation constants necessary for equalizing dynamic operations of each reel drive means, in accordance with the reel status amount from each reel status sensing means and the detected value from said tape tension detecting means;
• and
• means for selecting a compensation constant corresponding to the instantaneous tap roll radii from said compensation constants calculated by and stored in said arithmetic and storage means in response to said sensing means and for setting the selected compensation constant as a compensation constant for said reel drive means.