Method and apparatus for low cost thermal printing

Abstract

A method and apparatus for low cost thermal printing in a thermal printer having a software controlled thermal print head that moves in relation to a print ribbon disposed adjacent to a print area of a printed medium. The thermal print head is selectively energized to heat the print ribbon which deposits the ink onto the printed medium as the print head moves in relation to the print ribbon in a print stroke. The cost of printing is decreased by efficient use of the ink on the print ribbon. Between print strokes, the print ribbon is displaced an incremental interval to position an unused portion of the print ribbon for printing on the printed medium during a subsequent print stroke. The precise displacement of the print ribbon may be software controlled based on the detection of indices disposed at spaced intervals along the print ribbon which further increases the efficient usage of ink on the print ribbon. The utilization of ink on the print ribbon is made more efficient by a software controlled generation of an italic or gray shade character font, which require less ink than solid block character fonts. Using less ink on the print ribbon, permits a decrease in the print ribbon displacement interval between print strokes, and also permits some portions of the print ribbon to be over-lapped by the print head during a subsequent print stroke. The utilization of ink on the print ribbon may also be made more efficient by mechanical or software controlled linear and lateral shifts of the printed characters during subsequent print strokes, which permits the utilization of ink between areas on the print ribbon where ink was depleted in a previous print stroke.