Ink-jet printing head having a plurality of actuator units and/or a plurality of manifold chambers

An ink-jet printing head comprising:

• a cavity unit;
• and
• an actuator which is superposed on the cavity unit and which consists of two actuator units that are separate from each other,
• the cavity unit having:
• a plurality of nozzles open in a front surface of the cavity unit and arranged in a plurality of rows for ejecting droplets of inks of respective different colors, the plurality of rows of the nozzles being spaced apart from each other in a direction substantially perpendicular to a direction of extension of the rows, and corresponding to said respective different colors of the inks;
• a plurality of pressure chambers arranged in a plurality of rows corresponding in number to the respective rows of the nozzles;
• a plurality of communication passages for communication between the respective pressure chambers and the respective nozzles;
• and
• a manifold portion for storing the inks of the respective different colors supplied from respective ink supply sources and re-filling the plurality of pressure chambers arranged in the plurality of rows,
• the two actuator units of the actuator being arranged in the direction of extension of the plurality of rows of the nozzles, and each of the two actuator units having a plurality of active portions arranged in a plurality of rows which respectively correspond to the plurality of rows of the pressure chambers and which are selectively operable to deliver the inks from the corresponding nozzles,
• the plurality of nozzles in each of the plurality of rows including two groups of nozzles which respectively correspond to the two actuator units and which are arranged in the direction of extension of the plurality of rows,
• the plurality of pressure chambers in each of the plurality of rows including two groups of pressure chambers respectively corresponding to the two actuator units and the two groups of nozzles in each of the plurality of rows,
• the manifold portion having manifold chambers arranged in a plurality of rows respectively corresponding in number to the respective rows of the pressure chambers, each of the plurality of rows of the manifold chambers consisting of two manifold chambers which respectively correspond to the two actuator units and the two groups of pressure chambers, and each of which re-fills the pressure chambers of the corresponding group of pressure chambers, the two manifold chambers in each of the plurality of rows being arranged in the direction of extension of the plurality of rows of nozzles and aligned with each other, such that the two manifold chambers in each row correspond in number to the two groups of nozzles in the corresponding row of nozzles,
• each of the two manifold chambers in each of the plurality of rows being elongated in the direction substantially parallel to the direction of extension of the plurality of rows of nozzles, and being held in communication with the ink supply source, at one of opposite longitudinal end portions thereof which is remote from the other of said two manifold chambers in the direction of extension of said two manifold chambers, and
• the two manifold chambers in each of the plurality of rows being independent of each other such that the two manifold chambers inhibit flows of the ink between the two manifold chambers in a same row of the plurality of rows of manifold chambers.