Printer, printing method for printer, and program

A printing method for a printer that comprises a thermal head that has a plurality of heating elements arranged in a line, the printer being configured to print on a print medium having a thermal color developing layer, the printing method comprising:

• setting a first application period of a pulse of energizing current for applying to the plurality of heating elements during a scanning line time for one line to cause the thermal color developing layer to develop color;
• correcting a length of the set first application period based on an image to be printed;
• determining a print speed to be used in printing the whole image at a constant speed by extending the scanning line time so as to contain a maximum length of first application periods that have been corrected;
• and
• further correcting the length of the first application period so that a first ratio of the first application period of the pulse of energizing current during the scanning line time before the print speed is determined and a second ratio of the first application period of the pulse of energizing current during the scanning line time after the print speed is determined will be the same.

A non-transitory recording medium containing a program, the program being configured, when installed in a printer to cause a computer to execute a predetermined method, the printer comprising a thermal head that has a plurality of heating elements arranged in a line, the printer being configured to print on a print medium having a thermal color developing layer, the predetermined method comprising:

• setting a first application period of a pulse of energizing current for applying to the plurality of heating elements during a scanning line time for one line to cause the thermal color developing layer to develop color,
• correcting a length of the set first application period based on an image to be printed;
• determining a print speed to be used in printing the whole image at a constant speed by extending the scanning line time so as to contain a maximum length of first application periods that have been corrected;
• and
• further correcting the length of the first application period so that a first ratio of the first application period of the pulse of energizing current during the scanning line time before the print speed is determined and a second ratio of the first application period of the pulse of energizing current during the scanning line time after the print speed is determined will be the same.