| 摘要 |
PURPOSE:To clean a nozzle part of a printing head and enable constantly stable jetting of ink droplets, by sucking a minute quantity of an ink from a printing head through minimizing an ink-sucking force by a controlling means, at a non-printing time after a printing operation. CONSTITUTION:When a valve 5 is opened and a suction pump 4 is operated in the condition where a cap 2 makes gas-tight contact with a printing head 1, 8 negative pressure is developed in the cap 2 by the operation of the pump 3, and air is introduced from the atmosphere into the cap 2 through the valve 5. In this case, a small-diameter pipe 6 exerts a resistance determined by the diameter and length of the pipe 6 on the air being introduced, resulting in the condition where the negative pressure in the cap 2 is not completely canceled, so that an ink flows out from the head 1 in a minute quantity. By the outflow of the ink, the front surface of the part of nozzles 13 of the head 1 is cleaned, and a dried ink, refuse, dust and the like are removed. The minute quantity in which the ink flows out is set in such a range that a sufficient cleaning effect is obtained and the consumption of the ink does not cause any practical problem, and the minute quantity is suitably about 0.0035-0.01cc per such ink-sucking operation. |
