| 摘要 |
PURPOSE:To make it possible to control static pressure in an ink sump, in an ink jet printing head, by controlling the opening and closing valve of an ink supply means by the output of a liquid level detecting circuit connected to the liquid level sensing part of a liquid column gange. CONSTITUTION:When an ink is supplied to an ink sump 105 for supplying the ink to plural nozzles to increase the static pressure of the ink and a liquid level 208 reaches an upper level sensor 209, an opening and closing valve 211 is closed by a signal sent from a liquid level detecting circuit part 301 through an opening and closing valve drive circuit part 302. In addition, when the static pressure of the ink is lowered by injecting the ink and the liquid level 208 in the liquid column gange 203 is lowered to a lower level sensor 210, the opening and closing valve 211 is opened again to supply the ink. As mentioned above, the equilibrium state with the surface tension of the ink in a nozzle hole can be held by controlling the static pressure in the ink sump. |
