1. Field of the Invention
This invention relates to a thermal transfer printer for color printing and, in particular, to a thermal transfer printer for color printing on a recording paper by using an ink sheet having sequential sections of ink of three primary colors or four colors including black. Each color is applied to a section of the ink sheet sequentially in segments equal to the length and width of a sheet of recording paper and the printer is programed to advance the ink sheet until the desired color reaches the print position.
2. Description of the Prior Art
A thermal transfer printer used as an output printer in the computer system, word-processor, and the like is readily capable of color printing by the application of ink of several different colors successively to the same page of the same printing medium. Such a printer can be used for outputting such data as displayed by the so-called computer graphics or to produce multi-color images.
A thermal transfer printer capable of color printing as described above has been disclosed in, for example, the Japanese Patent, Laid-open No. 58-140266 (1983).
In the thermal transfer printer such as above, generally, an ink sheet having sequential sections of ink in four colors including three primary colors (yellow, magenta, and cyan) and black and a recording paper are put one upon another and carried to a contact position between a thermal transfer head and the platen so that all colors of ink are thermally transferred to the recording paper in succession. Each time that printing in one color is completed, the recording paper is reversed, then brought forward and again printed in the succeeding color on the same page as that previously printed, the repeat of such process providing multi-color printing.
However, a thermal transfer printer of this type has a problem in that the recording paper and the ink sheet are transported together in the initial stage. When the machine is turned on, recording paper is fed until it reaches a sensor which is beyond the thermal transfer head a distance approximating a sheet of paper. The transfer is then retracted from contact with the platen and the machine is ready to print. The recording paper is relatively inexpensive, so this small amount of waste is not critical. The ink sheet, however, is very expensive and, since the ink sheet is transported with the recording paper, one of the colors advances past the transfer head. If that color is that which is programed to be printed, the ink sheet will be advanced until that color is again detected. As a consequence, four full ink faces can be, and usually are, wasted. This wastefulness is very expensive and most undesirable.