Method and apparatus for controlling tension in tape progressed along a feed path

A thermal transfer printer for transferring marking material from a transfer ribbon onto adjacent receiving paper in a predetermined pattern, said transfer ribbon being transferable between ribbon supply and ribbon take-up reels and said paper being transferable between paper supply and paper take-up reels, said printer comprising:

• a thermal print head for effecting the desired transfer of said marking material from said transfer ribbon onto said receiving paper, said print head being positioned adjacent said transfer ribbon between said ribbon supply and ribbon take-up reels;
• a roller, positioned adjacent said receiving paper, for maintaining the desired orientation of said transfer ribbon and said receiving paper with respect to said print head;
• a roller motor, coupled to said roller, for producing motion of said roller allowing said roller to maintain said desired orientation of said transfer ribbon and said receiving paper with respect to said print head;
• a ribbon take-up reel motor, coupled to said ribbon take-up reel, for applying an adjustable torque to said ribbon take-up reel;
• a ribbon and paper advancement indicator for producing a reference signal representative of any change in said desired orientation of said ribbon and paper with respect to said print head;
• a ribbon take-up reel control indicator for producing a ribbon take-up feedback signal representative of any change in position of said ribbon take-up reel resulting from said adjustable torque applied by said ribbon take-up reel motor, said processing means producing a paper take-up control signal in reel motor;
• and
• processing means for producing a ribbon take-up control signal in response to said reference signal and said ribbon take-up feedback signal, said ribbon take-up control signal being provided to said ribbon take-up reel motor to adjust said torque applied to said ribbon take-up reel sufficiently to produce the desired tension in said ribbon between said roller and said ribbon take-up reel.

The process of maintaining a desired tension in a tape disposed between an advancement device and a rotatable reel, said advancement device being operable to advance said tape by a predetermined distance, the method comprising the steps of:

• producing a reference signal in response to the operation of said advancement device;
• producing a first feedback signal in response to the operation of said reel;
• comparing said reference signal and said first feedback signal to produce a first comparison signal;
• and
• adjusting the operation of said reel in response to said first comparison signal to maintain said desired tension in said tape substantially independent of the operation of said advancement means.