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Abstract

A thermal transfer color printer for printing color images on individual sheets of paper. One sheet of paper at a time is removed from a stack of paper stored in a cassette and this sheet is transported by a reversible platen roller in a first or forward direction at a first predetermined rate. While the sheet of paper is gripped between the reversible platen roller and one or more pinch rollers, slack is removed by a slack removing device. A multicolored ink ribbon with successively arranged color segments also is transported in the first direction at the same predetermined rate. A thermal printhead presses against the reversible platen roller to press the ink ribbon and sheet of paper together as they move in the first direction. Energization of the thermal elements on the thermal printhead by color component signals corresponding to the current color of the ink ribbon causes the particular current color to be thermally and selectively transferred to the sheet of paper. The thermal printhead then disengages the platen roller and the sheet of paper is transported in a set distance in a second direction opposite the first direction, and at a second predetermined rate, in order to repeat the process of thermally transferring other colors to the sheet of paper. During the back and forth movement of the sheet of paper, the reversible platen roller and the pinch rollers continuously grip the sheet of paper in order to precisely control the position of the sheet of paper to thereby avoid distortion. A complete color image is formed on the sheet of paper by superimposing the multiple colors of the ink ribbon as the sheet of paper and the different colors of the ink ribbon repeatedly move past the selectively energized thermal elements of the thermal printhead.

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