Tape tension control for a magnetic recording and reproducing apparatus

A magnetic recording and reproducing apparatus comprising:

• supply reel drive means for driving a supply reel on which a magnetic tape is wound;
• magnetic tape supply means for driving the magnetic tape at a specified speed along a magnetic tape path from said supply reel via a head cylinder on which a rotary magnetic head is mounted;
• a supply side movable pin located in the magnetic tape path from said supply reel to said head cylinder for varying a length of the magnetic tape path between said supply reel and said head cylinder;
• supply side tape actuator means for driving said supply side movable pin;
• tension detecting means for detecting a tension of the magnetic tape in accordance with said supply side movable pin;
• tension control means for controlling and maintaining the tension of the magnetic tape at a specified value by operating said supply reel drive means alone or in cooperation with said supply side tape actuator means;
• acceleration detecting means for detecting an acceleration of a deck on which the magnetic recording and reproducing apparatus is mounted in a direction of movement of said supply side movable pin and for outputting an acceleration signal indicative of the detected acceleration;
• and
• an adder/subtractor for adding/subtracting the acceleration signal output by said acceleration detecting means to/from an output signal of said tension detecting means indicative of a detected tension of the magnetic tape,
• said tension control means operating said supply reel drive means and said supply side tape actuator means based on an output signal of said adder/subtractor.