Patent ID: 8485745

Claim:
A thermal printer comprising: a first thermal head configured to be brought into contact with a first side of a printing medium and energize a plurality of first heater elements to print dot image data on the first side of the printing medium; a second thermal head configured to be brought into contact with a second side of the printing medium and energize a plurality of second heater elements to print dot image data on the second side of the printing medium; a controller configured to set energization cycles of the first and second thermal heads to a time period that is more than double an energization time required for the first and second thermal heads to print one dot-line data, the controller is also configured to energize the first thermal head, and start energizing the second thermal head after the energization for the first thermal head is completed, and a feeding motor configured to advance the printing medium half a dot length of a print dot in a feeding direction after the energization for the first thermal head is completed and before the energization for the second thermal head is started, wherein a position of dot image data on the first side of the printing medium and a position of dot image data on the second side of the printing medium are displaced by half of the dot length, wherein a timing when the energization for the second thermal head is completed is prior to an end of the time period, and wherein the controller controls the energization cycles of the first and second thermal heads such that the energization time required for the first thermal head to print one dot-line data and energization time required for the second thermal head to print one dot-line data do not overlap each other and both the first and second thermal heads are deenergized before the end of the time period such that during at least a portion of the time period neither the first thermal head nor the second thermal head are energized, and wherein the plurality of first heater elements are arranged in a line and the plurality of second heater elements are arranged in a line such that an arrangement direction of the first heater elements and the second heater elements is at right angles to the feeding direction of the printing medium.