Importance

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Abstract

An improved ink jet head is provided. This improved ink jet head comprises a diaphragm, which is part of an ink chamber. The diaphragm includes a segment which contacts an opposing wall by a drive voltage lower than that for the rest of the diaphragm. The ink jet head also comprises an opposing wall opposite to the diaphragm. When the pressure for ink droplet ejection is generated, the segment of the diaphragm contacts the opposing wall, creating an extremely low compliance state. After ink droplet ejection, the segment of the diaphragm separates from the opposing wall, producing a high compliance state that absorbs the pressure created in the ink chamber by oscillation in the ink channel. Thus, pressure in the ink chamber resulting from ink vibration in the ink path including the ink chamber is buffered to prevent satellite emissions. When plural different gaps are formed between the diaphragm and the opposing wall to create the segments requires different drive voltage for contacting the opposing wall, the part of the diaphragm contributing to ink droplet ejection can be selected by appropriately controlling the voltage applied to opposing electrodes. The mass of the ejected ink droplets can thus be variably controlled. Drive at a lower drive voltage is also possible because contact with the opposing wall is propagated from the segment of the diaphragm to the other parts of the diaphragm. A high ink nozzle density is also achieved in an ink jet head using an electrostatic actuator without increasing the drive voltage.

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First Claim