Patent ID: 7600861

Claim:
An inkjet head comprising: a passage unit comprising a common ink chamber, and an individual ink passage leading from an outlet of the common ink chamber through a pressure chamber to an ink ejection port; and an actuator that can selectively take a first state wherein a volume of the pressure chamber is V 1 and a second state wherein the volume of the pressure chamber is V 2 larger than V 1 , the actuator changing from the first state to the second state and then returning to the first state to eject ink from the ejection port, a proper oscillation period Ts of an oscillation generated by integral deformation of the actuator and the pressure chamber when ink is ejected from the ejection port, and a proper oscillation period Td of ink filling up a first partial passage in the individual ink passage leading from an outlet of the pressure chamber to the ejection port, satisfying a condition that Ts/Td is not less than 0.36 and not more than 0.90; or not less than 1.1 and not more than 1.7.