Bidirectional ink sheet driving mechanism in a thermal transfer printer

A thermal transfer multi-color line printer wherein recording paper is imprinted from an ink sheet having a plurality of color frames, the recording paper is overlapped on one color frame of the ink sheet, carried forward with the ink sheet for initial setting and printed by a thermal head while being carried forward, and the recording paper is carried in a reverse direction after said printing from said color frame and overlapped on another color frame of the ink sheet for a next printing, comprising

• a supply roll for an ink sheet around which an unsued portion of said ink sheet is wound;
• a take up roll for winding a used portion of said ink sheet therearound;
• a carrier roller positioned between both rolls for carrying the ink sheet in both the forward and the reverse direction;
• a motor for applying a rotational driving force to the carrier roller;
• a first holding reel for holding said take up roll which is rotationally driven;
• a first shaft located between said carrier roller and said take up roll;
• a first rotating member and a second rotating member supported by said first shaft and provided with a one-way clutch therebetween, and the first rotating member being driven by the rotation of said carrier roller and the one-way clutch transmitting the rotational driving power to the second rotating members when the ink sheet is carried in the forward direction;
• a third rotating member being driven by the second rotating member, being fitted to a second shaft which supports said holding reel for said take up roll with a one-way clutch on said second shaft that prohibits the rotation of said first holding reel when the ink sheet is carried in the reverse direction;
• a first friction member, which is fitted to the second shaft and disposed between said first holding reel for said take up roll and the third rotating member, for transmitting the rotational driving force of said first friction member from the third rotating member to said first holding reel for said take up roll by a frictional force thereof when the ink sheet is carried in the forward direction and applying a brake power to first said holding reel for said take up roll by a frictional force thereof so as to apply a back tension to the ink sheet when the ink sheet is carried in the reverse direction and rotationally drives the take up roll;
• a second holding reel for holding said supply roll which is rotationally driven;
• a third shaft located between said carrier roller and said supply roll;
• a fourth rotating member and a fifth rotating member supported by said third shaft and provided with a one-way clutch therebetween, and the fourth rotating member being driven by the rotation of said carrier roller and the one-way clutch transmitting the rotational driving power to the fifth rotating member when the ink sheet is carried in the reverse direction;
• a sixth rotating member being driven by the fifth rotating member, being fitted to a fourth shaft which supports said second holding reel for said supply roll with a one-way clutch on said fourth shaft that prohibits the rotation of said second holding reel when the ink sheet is carried in the forward direction;
• and
• a second friction member, which is fitted to the fourth shaft and disposed between said second holding reel for said supply roll and the sixth rotating member, for transmitting the rotational driving force of said second friction member from the sixth rotating member to said second holding reel for said supply roll by a frictional force, when the ink sheet is carried in the reverse direction and applying a brake power to said holding second reel for said supply roll by a frictional force thereof so as to apply a back tension to the ink sheet when the ink sheet is carried in the forward direction to rotationally drive the supply roll.