| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem in an inkjet head that when a downtime of printing is prolonged, a nozzle is clogged by an increase of viscosity of ink in the nozzle or though the downtime does not result in clogging with the same, an ink droplet is not normally discharged to deteriorate a quality of an image depending on the duration of the downtime of printing. <P>SOLUTION: The inkjet unit has an operation means 11 connected to the inkjet head 1 and obtaining pressure in an ink discharge opening portion based on the pressure detected by an ink circulation system 2 according to a preliminarily established operation expression. A pressure determination means 12 compares the value Y obtained by the operation means with a reference value Pn to determine whether the obtained value is positive pressure or negative pressure to the reference value. A negative pressure adjustment means 23 is connected to the ink circulation system 2, and when the obtained value is determined to be the positive pressure to the reference value Pn, the negative pressure value to the ink discharge opening is increased. The pressure determination means 12 can change the reference value Pn to the negative pressure side, and by this the viscosity-increased ink or the like is removed from the inside of the nozzle. <P>COPYRIGHT: (C)2012,JPO&INPIT |
