| 摘要 |
PURPOSE:To enable satisfactory printing operation to be performed irrespective of dust settlement condition in a filter by providing a pressure control device which controls an ink pressure to be applied to a recording head in accordance with a print state. CONSTITUTION:A control device 131 drives a pulse motor 154 in accordance with the number of counted copies and thereby rotates a cam 155 to adjust the height of an ink supply system. In addition, the control device 131 controls a difference (h)[mm] in the height from the lower end of a recording head 112 to an ink surface inside an ink tank 113. That is, the device 131 lowers the position of the ink supply system to increase a negative pressure, if each filter 123a, 123b is newly installed and a pressure loss is low resulting in an adequate ink supply. Therefore, if the pressure loss of each filter 123a, 123b increases, an ink supply pressure increases in proportion to the increase of the pressure loss and thus an adequate ink supply is ensued and the failure to discharge ink due to an insufficient pressure application is prevented. Further, thermal energy is caused to generate in an electricity/heat converter 52 so that film ebullition occurs to form bubbles in an ink liquid path. Consequently, the growth of these bubbles allows ink droplets to be discharged from a discharge orifice 51. |
