| 摘要 |
PROBLEM TO BE SOLVED: To prevent adhesion between a diaphragm and an electrode caused by a van der Waals force, an electrostatic attraction force, a liquid crosslinking force and a hydrogen combining force, etc., to be generated between the diaphragm and the opposing electrode in an actuator of an electrostatic ink jet head. SOLUTION: The electrostatic actuator is equipped with the diaphragm 5 forming a bottom part of an ink chamber 6, an opposing electrode 12 arranged in opposite to the diaphragm, and a diaphragm chamber between the diaphragm 5 and the opposing electrodes 12. The surface roughness is set to Ra (th) when the attraction force between the diaphragm 5 and the opposing electrode 12, when brought into contact with each other, becomes equal to a restoring force basing on the elasticity of the diaphragm 5, while the opposing electrode 12 surface in the surface roughness Ra is set to greater than Ra (th). The oxidized film 13 surface as a protection film of electrode is made rough by etching to be greater than Ra (th) in the surface roughness.
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