Liquid discharge head

A liquid discharge head comprising:

• a piezoelectric body including a plurality of stacked piezoelectric layers having a first end and a second end separated in a first direction orthogonal to a stacking direction of the plurality of piezoelectric layers;
• a plurality of individual electrodes located at a first plane orthogonal to the stacking direction;
• a first common electrode located at a second plane which is orthogonal to the stacking direction and different in position in the stacking direction from the first plane and different in position in the stacking direction from a neutral plane of the piezoelectric body;
• and
• a second common electrode located at a third plane which is orthogonal to the stacking direction and different in position in the stacking direction from the first plane and different in position in the stacking direction from the neutral plane of the piezoelectric body,
• wherein the neutral plane is positioned between the third plane and one of the first and second planes in the stacking direction,
• wherein a relation of
• D1×S1+D2×S2>D3×S3
• is satisfied, where S1 is a sum of the areas of the plurality of individual electrodes, S2 is an area of the first common electrode, S3 is an area of the second common electrode, D1 is a distance between the neutral plane and the first plane in the stacking direction, D2 is a distance between the neutral plane and the second plane in the stacking direction, and D3 is a distance between the neutral plane and the third plane in the stacking direction,
• wherein the plurality of individual electrodes include a plurality of individual electrode arrays arranged at intervals between the first end and the second end,
• wherein the plurality of individual electrode arrays include a first individual electrode array, a second individual electrode array adjacent to the first individual electrode array in the first direction, a third individual electrode array adjacent to the second individual electrode array in the first direction, and a fourth individual electrode array adjacent to the third individual electrode array in the first direction,
• wherein the first individual electrode array is positioned between the first end and the second individual electrode array in the first direction, the second individual electrode array is positioned between the first individual electrode array and the third individual electrode array in the first direction, and the third individual electrode array is positioned between the second individual electrode array and the fourth individual electrode array in the first direction,
• wherein the plurality of individual electrodes forming the first individual electrode array are arranged in a second direction being orthogonal to the stacking direction and intersecting the first direction, the plurality of individual electrodes forming the second individual electrode array are arranged in the second direction, the plurality of individual electrodes forming the third individual electrode array are arranged along the second direction, and the plurality of individual electrodes forming the fourth individual electrode array are arranged in the second direction,
• wherein the second common electrode includes a first extending portion extending in the second direction to pass through between the first individual electrode array and the second individual electrode array in the first direction, a plurality of first projecting portions projecting from the first extending portion toward the second end, a second extending portion extending in the second direction to pass through between the third individual electrode array and the fourth individual electrode array along the first direction, and a plurality of second projecting portions projecting from the second extending portion toward the first end,
• wherein the respective first projecting portions overlap partially with one of the plurality of individual electrodes forming the second individual electrode array in the stacking direction, and the respective second projecting portions overlap partially with one of the plurality of individual electrodes forming the third individual electrode array in the stacking direction, and
• wherein the liquid discharge head further comprises a plurality of conductor layers which are formed on the third plane between the plurality of first projecting portions and the plurality of second projecting portions in the first direction, without contact with the second common electrode and without contact with each other.