| 摘要 |
PURPOSE:To simplify the construction of a controlling circuit for varying a power source voltage in accordance with the number of heating resistors simultaneously supplied with an electric current, by controlling a generated voltage on the basis of the terminal voltage of a capacitor which is charged or discharged by a switch controlled on the basis of printing data. CONSTITUTION:The capacitor 35 is discharged by a transistor 36 turned ON by a resetting signal RS, and is charged by a transistor 38 turned ON when a printing data signal DS is brought to a high level. The terminal voltage of the capacitor 35 charged while the signal DS is at a high level is raised in accordance with the number of the heating resistors which are simultaneously supplied with an electric current, and a controlling signal DC given to a buffer amplifier 5 is also increased in accordance with said number. As a result, a supply voltage VP generated by an electric controlling element 8 is also increased to such a value as to compensate for the power loss in a current-supplying circuit which is varied is accordance with said number. |
