| 摘要 |
PROBLEM TO BE SOLVED: To reduce failure of an air pump in an ink circulation type ink jet printer in which a pressure tank and a negative pressure tank are arranged below an ink jet head and in which a positive pressure and a negative pressure are imparted to the pressure tank and the negative pressure tank respectively by the air pump at the time of ink circulation.SOLUTION: A control unit, when starting ink circulation, executes preliminary processing for sealing a pressure tank 21 by a pressure side atmosphere open valve 53, and, in a state where a negative pressure tank 24 is opened to the atmosphere by a negative pressure side atmosphere open valve 57, for feeding ink toward an ink jet head 11 from the pressure tank 21 by imparting a positive pressure to the pressure tank 21 by an air pump 59, and also, for feeding the ink to the pressure tank 21 from the negative pressure tank 24 by an ink pump 25 until liquid level height of the negative pressure tank 24 becomes less than reference hight. |
