| 摘要 |
PURPOSE:To prevent an ink from dripping and ink droplets from being jetted erroneously and thereby to obtain an ink jet with excellent leading-edge response by preoperating a head immediately before changing over to an informative picture signal, in the ink-on-demand type printer. CONSTITUTION:A picture signal Vid is inputted into the first, second and third filp-flops 11, 12, 13, where signal outputs Q1, Q2, Q3 sequentially delayed by the period of a clock signal Cp are generated and are inputted into an OR circuit 14. An output Or from the circuit 14 is sampled by the clock signal Cp in an AND circuit 15 and is impressed as an output An on an amplifying circuit 16. When the output Q3 is low, the amplifying circuit 16 amplifies the output An to an injection signal Vo of a level lower than a threshold value Vth of the ink head 5. When the output Q3 becomes high, a switch 20 of a reference voltage setting circuit 17 is changed over and the output An is amplified to an injection signal Vo higher than the threshold value Vth. Accordingly, the voltage Vo lower than the threshold value is generated immediately before the change-over to the informative picture signal, so that the preliminary operation of the head is performed. |
