| 摘要 |
PURPOSE:To secure uniformity of printed density, by a method wherein the resistance of each head stored, and a driving signal with a pulse width calculated from the stored value and an impressed voltage is impressed on each head. CONSTITUTION:When a printing operation is started, each of resistance R1, R2...Rn of the thermal heads 1 is read from a memory element 22 into a CPU25. Further, a voltage VB controlled to a fixed voltage is read into the CPU25 as a digital value through an AD converter 21. A pulse width t1, t2...tn for each of the thermal heads 1 is determined from the resistance R1, R2...Rn and the voltage VB. When a driving circuit 27 outputs a driving signal based on the pulse width tn, an AND circuit 3 outputs ''1'' or ''0'' in accordance with image information from a shift register 2, thereby controlling the operation of transistor 4. Accordingly, predetermined heat generation is effected in the thermal heads 1 corresponding to the image information. |
