CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2019-069633 filed on Apr. 1, 2019, the content of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Aspects of the disclosure relate to a piezoelectric actuator and a liquid ejection apparatus including the piezoelectric actuator.

BACKGROUND

A known piezoelectric actuator includes a lower electrode, a first piezoelectric layer disposed on the lower electrode, an intermediate electrode disposed on the first piezoelectric layer, a second piezoelectric layer disposed on the intermediate electrode, and an upper electrode disposed on the second piezoelectric layer. The lower electrode and the upper electrode electrically connect to each other by an electrode connector. An upper/lower electrode wire is led from the electrode connector. An intermediate electrode wire is lead from the intermediate electrode.

SUMMARY

The upper/lower electrode wire and the intermediate electrode wire are led on the same side of the piezoelectric actuator relative to the intermediate electrode. For electrical insulation between the upper/lower electrode wire and the intermediate electrode wire, an insulation layer is required between the upper/lower electrode wire and the intermediate electrode wire, which may lead to a complicated configuration of the piezoelectric actuator. Even if the insulation layer is provided, electrical reliability of the piezoelectric actuator may be reduced because a distance between the wires is short.

Aspects of the disclosure provide a piezoelectric actuator and a liquid ejection apparatus including the piezoelectric actuator that may achieve a simplified configuration and increase electrical reliability.

According to one aspect of the disclosure, a piezoelectric actuator comprise a common electrode, a first piezoelectric body disposed at one side of the common electrode in a thickness direction of the common electrode, an individual electrode disposed at one side of the first piezoelectric body in the thickness direction, a second piezoelectric body disposed at one side of the individual electrode in the thickness direction, a first conductive pattern disposed at one side of the second piezoelectric body in the thickness direction, a second conductive pattern disposed at the one side of the second piezoelectric body in the thickness direction, the second conductive pattern being insulated from the first conductive pattern, and a third conductive pattern disposed at the one side of the second piezoelectric body in the thickness direction. The third conductive pattern is insulated from the first conductive pattern and the second conductive pattern. The first conductive pattern electrically connects to the common electrode, and does not to electrically connect to the individual electrode. The second conductive pattern does not electrically connect to either the common electrode or the individual electrode. The third conductive pattern does not electrically connect to the common electrode, and electrically connects to the individual electrode. The first conductive pattern is disposed at one side of the second conductive pattern in a perpendicular direction that is perpendicular to the thickness direction. The third conductive pattern is disposed at an other side of the second conductive pattern in the perpendicular direction.

According to another aspect of the disclosure, a liquid ejection apparatus comprises a pressure chamber substrate having a pressure chamber formed therein, a diaphragm disposed at one side of the pressure chamber substrate in the thickness direction, the diaphragm covering the pressure chamber, a common electrode disposed at one side of the diaphragm in the thickness direction, a first piezoelectric body disposed at one side of the common electrode in the thickness direction, an individual electrode disposed at one side of the first piezoelectric body in the thickness direction, a second piezoelectric body disposed at one side of the individual electrode in the thickness direction, a first conductive pattern disposed at one side of the second piezoelectric body in the thickness direction, a second conductive pattern disposed at the one side of the second piezoelectric body in the thickness direction, the second conductive pattern being insulated from the first conductive pattern, and a third conductive pattern disposed at the one side of the second piezoelectric body in the thickness direction. The third conductive pattern is insulated from the first conductive pattern and the second conductive pattern. The first conductive pattern electrically connects to the common electrode, and does not electrically connect to the individual electrode. The second conductive pattern does not electrically connect to either the common electrode or the individual electrode. The second conductive pattern, the common electrode, and the individual electrode overlap, in the thickness direction, with the pressure chamber. The third conductive pattern does not electrically connect to the common electrode, and electrically connects to the individual electrode. The first conductive pattern is disposed at one side of the second conductive pattern in a perpendicular direction that is perpendicular to the thickness direction. The third conductive pattern is disposed at another side of the second conductive pattern in the perpendicular direction.

According to still another aspect of the disclosure, a piezoelectric actuator comprises a first actuator array and a second actuator array. The first actuator array includes a common electrode, a first piezoelectric body disposed at one side of the common electrode in a thickness direction of the common electrode, an individual electrode disposed at one side of the first piezoelectric body in the thickness direction, a second piezoelectric body disposed at one side of the individual electrode in the thickness direction, a first conductive pattern disposed at one side of the second piezoelectric body in the thickness direction, a second conductive pattern disposed at the one side of the second piezoelectric body in the thickness direction, the second conductive pattern being insulated from the first conductive pattern, and a third conductive pattern disposed at the one side of the second piezoelectric body in the thickness direction. The third conductive pattern is insulated from the first conductive pattern and the second conductive pattern. The second actuator array includes a common electrode, a first piezoelectric body disposed at one side of the common electrode in the thickness direction, an individual electrode disposed at one side of the first piezoelectric body in the thickness direction, a second piezoelectric body disposed at one side of the individual electrode in the thickness direction, a first conductive pattern disposed at one side of the first piezoelectric body of the second actuator array in the thickness direction, a second conductive pattern disposed at the one side of the first piezoelectric body of the second actuator array in the thickness direction, the second conductive pattern of the second actuator array being insulated from the first conductive pattern of the second actuator array, a third conductive pattern disposed at the one side of the fourth second piezoelectric body of the second actuator array in the thickness direction. The third conductive pattern of the second actuator array is insulated from the first conductive pattern of the second actuator array and the second conductive pattern of the second actuator array. The first conductive pattern of the first actuator array electrically connects to the common electrode of the first actuator array, and does not electrically connect to the individual electrode of the first actuator array. The second conductive pattern of the first actuator array does not electrically connect to either the common electrode or the individual electrode of the first actuator array. The third conductive pattern of the first actuator array does not electrically connect to the common electrode of the first actuator array, and electrically connects to the individual electrode of the first actuator array. The first conductive pattern of the second actuator array electrically connects to the common electrode of the second actuator array, and does not electrically connect to the individual electrode of the second actuator array. The second conductive pattern of the second actuator array does not electrically connect to either the common electrode or the individual electrode of the second actuator array. The third conductive pattern of the second actuator array does not electrically connect to the common electrode of the second actuator array, and electrically connects to the individual electrode of the second actuator array. The second conductive pattern of the first actuator array and the second conductive pattern of the second actuator array are disposed between the first conductive pattern of the first actuator array and the first conductive pattern of the second actuator array in a perpendicular direction that is perpendicular to the thickness direction. The third conductive pattern of the first actuator array and the third conductive pattern of the second actuator array are disposed between the second conductive pattern of the first actuator array and the second conductive pattern of the second actuator array in the perpendicular direction.

According to aspects of the disclosure, configuration of the piezoelectric actuator may be simplified and electrical reliability of the piezoelectric actuator may be increased.

