| 摘要 |
PURPOSE:To obtain a thermal head capable of changing the size of a recording dot within the same current supply time and capable of performing high speed recording, in performing halftone recording, by selectively turning switching circuits ON to change the value of the current flowing to a heat generating resistor. CONSTITUTION:A heat generator 1 is constituted by connecting switching circuits 6a1, 6a2, 6a3 having three kinds of ON-resistors r1, r2, r3 to a control electrode 2 without being divided into heat generating elements. By selectively turning the switching circuits 6a1-6a3 ON, 8 stages of currents can be made to flow to the heat generator 1 and the energies corresponding to said currents can be generated. Therefore, 8 stages of medium contrast densities can be obtained within the same current supply time. As a result, since halftone recording can be performed without changing the time required in supplying a current to the heat generator 1, a recording speed can be increased. |
