Liquid ejection apparatus, controlling method thereof, and computer-readable medium for liquid ejection

A liquid ejection apparatus comprises a plurality of piezoelectric element units, which can be driven to eject liquid by changing a drive voltage, and a control device. The control device may calculate an accumulated time for each of the piezoelectric element units. The accumulated times may be a time that a respective piezoelectric element unit is in a driven state. The control device may also identify a first piezoelectric element unit having a maximum accumulated time and a second piezoelectric element unit having a minimum accumulated time from among the piezoelectric element units. The control device may reduce the drive voltage applied to one or more of the piezoelectric element units that are not in the driven state to a lower voltage, when the control device determines that the difference between the maximum accumulated time and the minimum accumulated time is less than a predetermined time.