Abstract: The backing pressure of an ink tank is controlled. The ink tank is connected to a pressure control apparatus. The pressure control apparatus has first and second check valves. When the internal pressure of the ink tank becomes smaller than that of outside atmosphere by a first predetermined pressure or more, the first check valve is switched into an open state to connect the outside atmosphere and the ink tank. To the contrary, when the internal pressure of the ink tank becomes larger than that of outside atmosphere by a second predetermined pressure or more, the second check valve is switched to an open state to connect the ink tank with the outside atmosphere. Therefore, the internal pressure of the ink tank is controlled precisely enough to stabilize the meniscus.

Abstract: The back pressure of an ink tank is controlled. A porous body is arranged inside the ink tank, the lower end of the porous body contacts an ink, and the ink ascends inside the porous body due to a capillary force. The upper end of the porous body is not immersed in the ink, and a maximum ascending force acts upon the ink stored in the ink tank. Therefore, the ink does not leak from a discharge head located lower than the ink tank. Further, because the ink is accumulated under the porous body and the amount of the ink contacting the porous body is small, components of the ink are less susceptible to deterioration.

Abstract: Vibration is prevented from being transmitted via a common ink chamber or a fixed substrate. A porous member is disposed between the common ink chamber and a pressure generation chamber so that a discharge liquid passes through the interior of the porous member to move from the common ink chamber to the pressure generation chamber. Vibration generated in one pressure generation chamber is attenuated through the porous member when the vibration is transmitted to another pressure generation chamber via the common ink chamber; and thus, no cross-talk is generated. Furthermore, when piezoelectric vibrators having different lengths are mounted on the same fixed substrate and have the resonance frequencies different from each other, vibration is not transmitted to another pressure generation chamber via the fixed substrate and the piezoelectric vibrator; and therefore, the cross-talk is much less likely to be generated.

Abstract: Vibration is prevented from being transmitted via a fixed substrate. In order to set the resonance frequencies of the vibration of piezoelectric vibrators to be different from each other, the piezoelectric vibrators having different lengths are attached to the same fixed substrate. Even if residual vibration of a pressure generation chamber, which is expanded/contracted by a piezoelectric vibrator to which a voltage is applied, is transmitted to the fixed substrate; and even if the vibration is transmitted to another piezoelectric vibrator via the fixed substrate; another piezoelectric vibrator does not vibrate because the resonance frequencies between the piezoelectric vibrators are different from each other. Consequently, the pressure generation chamber in contact with the piezoelectric vibrator is not expanded or contracted by the vibration.

Abstract: The backing pressure of an ink tank is controlled. The ink tank is connected to a pressure control apparatus. The pressure control apparatus has first and second check valves. When the internal pressure of the ink tank becomes smaller than that of outside atmosphere by a first predetermined pressure or more, the first check valve is switched into an open state to connect the outside atmosphere and the ink tank. To the contrary, when the internal pressure of the ink tank becomes larger than that of outside atmosphere by a second predetermined pressure or more, the second check valve is switched to an open state to connect the ink tank with the outside atmosphere. Therefore, the internal pressure of the ink tank is controlled precisely enough to stabilize the meniscus.

Abstract: The back pressure of an ink tank is controlled. A porous body is arranged inside the ink tank, the lower end of the porous body contacts an ink, and the ink ascends inside the porous body due to a capillary force. The upper end of the porous body is not immersed in the ink, and a maximum ascending force acts upon the ink stored in the ink tank. Therefore, the ink does not leak from a discharge head located lower than the ink tank. Further, because the ink is accumulated under the porous body and the amount of the ink contacting the porous body is small, components of the ink are less susceptible to deterioration.