| 摘要 |
PURPOSE:To enable gradations to be accurately provided, by a construction wherein a plurality of heating resistors are provided on a picture element line so that the heating part area of the resistors is gradually decreased with a factor of 1/2, and a plurality of split heating parts are symmetrically provided in at least the largest one and the second largest one of the resistors. CONSTITUTION:The heating resistors are provided on a picture element line at such positions as not to overlap with each other when printing a picture element. Namely, heating resistors A (A1, A2), B (B1, B2), C-F capable of printing with a total of 64 gradations are so provided that the heating part area thereof is sequentially decreased with a factor of 1/2, and at least the largest one A and the second largest one B of the resistors respectively have bisected heating parts A1, A2 and B1, B2 which are symmetrically disposed as shown. Accordingly, the thermal head itself can be manufactured in a simple construction, gradations can be accurately provided in printing, and high fidelity printed images can be obtained with inconspicuous blank parts as well as favorable linearity of the gradation. |
