| 摘要 |
PURPOSE:To eliminate irregularity of color density according to the printing direction of a both-direction printing head, by a method wherein heat is generated by passing an electric current individually through heating elements in either of two rows of heating elements which are placed on the outside peripheral surface of a cylindrical head made of glass or the like. CONSTITUTION:A common electrode element 5 is provided to be overlapped with two rows of the heating elements 211-21n, 221-22n which are placed on the outside peripheral surface of the cylindrical head made of glass or the like, and individual electrodes 611-61n, 621-62n are provided correspondingly to the heat elements to constitute the head 1. When the center line of the head 1 is maintained to be orthogonal to a thermal printing paper 3 and a platen 4, printing in the printing direction (+) is performed by the electrode provided at the position corresponding to a head inclination angle of +theta0 (curve E) while the printing in the printing direction (-) is performed by the electrode provided at the position corresponding to a head inclination angle of -theta0 (curve F). In both cases of printing, the maximum color density Dmax is obtained. When there is a stagger of an angle DELTAtheta in the printing direction (+), the printing in the direction (+) is performed in the condition corresponding to a point R, while the printing in the direction (-) is performed in the condition corresponding to a point S, and the difference in color density is extremely little. |
