| 摘要 |
PROBLEM TO BE SOLVED: To detect whether or not an insulation layer of a piezoelectric actuator of a liquid ejection head has a crack formed therein. SOLUTION: According to a liquid ejection head checking method, firstly, ink is filled in individual ink channels, each having a piezoelectric layer forming an internal wall of a pressure chamber (S16). Then electric characteristic value between a channel unit and a common electrode is measured (S17 to S19) by applying voltage to a point between the channel unit and the common electrode such that an electrode value of the former becomes higher than an electrode value of the latter if a pH value of the ink is larger than a pH value at a location corresponding to an isoelectric point of the piezoelectric layer. On the other hand, the measurement is carried out by applying voltage to a point between the channel unit and the common electrode such that an electrode value of the former becomes lower than an electrode value of the latter if a pH value of the ink is smaller than a pH value at a location corresponding to the isoelectric point of the piezoelectric layer. Then resistance values equal to or above a threshold value are selected (S20), and remaining resistance values are discarded (S21). COPYRIGHT: (C)2008,JPO&INPIT
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