Patent ID: 7948510

Claim:
A thermal printer comprising: thermal paper, which has a thermosensitive layer on one side or both sides, and is fed in a predetermined direction; a first thermal head which prints one side of the thermal paper; a second thermal head which prints the other side of the thermal paper; a control section which selectively prints one side and the other side of the thermal paper with the first and second thermal heads; a first mark sensor which detects a mark printed on one side of the thermal paper; a second mark sensor which detects a mark printed on the other side of the thermal paper; a determination section which determines whether the thermal paper is double-side thermal paper printable on both sides or one-side thermal paper printable on only one side, according to the detection results of the first and second mark sensors; a detection section which detects a print density for the thermal paper according to the outputs of the first and second mark sensors; and an adjustment section which adjusts print densities of the first and second thermal heads, according to the detection results of the detection section.