| 摘要 |
PURPOSE:To reduce time required for the pressure of ink to reach a fixed value at an initial stage of printing, and to reduce pressure pulsation and noises, by providing a plunger pump and a piezoelectric pump that are connected in series or in parallel, and by driving the plunger pump or both plunger pump and piezoelectric pump until the pressure of the ink fluid reach a fixed value, and by driving only the piezoelectric pump thereafter. CONSTITUTION:The pressure of the ink fluid is detected by a pressure sensor 5, and its pressure signal is sent to a pump control portion 9 to control driving of the pump. A plunger pump 7 is driven until the pressure of the ink fluid reach a set value, and when the value is exceeded, the driving of the plunger pump 7 is stopped, and a piezoelectric pump 8 is driven. The ink fluid is controlled to pass the inside of the pump which is not driven. And after the piezoelectric pump 8 is driven, its normal operation continues and the ink flows quietly with less pulsation, and the ink is supplied to a print head 4 through a magnetic valve 3. |
