| 摘要 |
A piezoelectric actuator has a first ceramic layer covering openings of pressure chambers, a first electrode provided over the plurality of pressure chambers, a second ceramic layer, a second electrode, a third ceramic layer and a third electrode in this order from the side of the pressure chambers. By measuring insulation resistance between a cavity unit and the first electrode in the state where ink is filled into the pressure chambers, a defect in the ceramic layer is detected.
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