| 摘要 |
PURPOSE:To prevent bubbles from entering when valve is closed and perform opening and closing of passageway and bubble discharging automatically, by providing a passageway which can be opened and closed, in outer chamber of double cavity type on-demand ink jet head and air chamber. CONSTITUTION:A passageway 16 which can be connected to an air chamber 7 is provided in an outer ink chamber 5. When bubbles are suctioned into the ink chamber 5 by variation of ink pressure, etc., supply of air to an air feed pipe 10 is stopped temporarily and pressures in the air chamber 7 and the outer chamber 5 are out of balance, leading to increase of pressure in the outer chamber 5. When an opening and closing device 17 is shut to resume supply of air by an electric signal 11, pressure in the air chamber 7 is increased and ink in the chamber 7 is discharged through an outlet 8. Thus, bubbles are discharged and prevented from reentering. Opening and closing of the passageway 16 is done automatically by electrical control. |
