| 摘要 |
<p>In order to prevent, in an operation for circulating liquid, an ejection port from sucking air or the ejection port from pushing out liquid, the subtank (3) for temporally storing ink to be supplied to the ink jet head (1) includes the air communication passage (34) opened or closed by the air communication valve (6d). The ink jet head (1) is communicated with the subtank (3) by the first passage (31) and the second passage (32) to constitute one circulation passage. In order to circulate the ink in the subtank (3) into the common liquid chamber (26), the main pump (4) is energized while the air communication valve (6) is being closed. When the circulation operation is stopped, the air communication valve (6d) is opened immediately after the stoppage of the main pump (4), thereby eliminating the differential pressure between the common liquid chamber (26) and the subtank (3) within a short period of time.
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