Abstract: A thermal printer comprising a print head having many thermal resistors, a movable carriage with the print head mounted thereon, and a ribbon cassette mounted on the carriage. Print data transmitted from a host system, such as a personal computer, in the form of character code is conducted through a processor into character buffers separately for each line, the print data are transformed into dot-matrix data by character generators CG(L) and CG(S), the converted dot matrix data for two lines are stored through the processor into a dot line buffer, the contents of the dot line buffer are transferred to a shift register, and a head driver for the thermal resistors is activated in response to data from the shift register.

Abstract: A thermal printer includes an inked ribbon, an inked ribbon take-up mechanism, a print head with two arrays of thermal resistance elements, a carriage mounting the print head, and a controller for controlling the print operation. The printer is provided with print mode switching circuit which selects low-speed print mode in which one array of thermal resistance elements is activated for each dot pitch for printing, or high-speed print mode in which the two arrays of thermal resistance elements are activated alternately for every dot pitch for printing. The printer having the print head with two thermal resistance elements is capable of high-speed printing and also high quality printing at a low print speed.