Liquid discharge apparatus

1. A liquid discharge apparatus comprising:

a diaphragm that has a first surface and a second surface facing in a direction opposite to the first surface;

a pressure chamber substrate laminated on the first surface and including a partition wall partitioning a pressure chamber communicating with a nozzle for discharging liquid;

a piezoelectric element laminated on the second surface and including a first active portion that overlaps a center of the pressure chamber when viewed in a thickness direction of the diaphragm and a second active portion that overlaps the pressure chamber at a position closer to an outer edge of the pressure chamber than the first active portion; and

a drive signal generation portion that generates a first drive signal that drives the first active portion and a second drive signal that drives the second active portion, wherein

the first drive signal includes a first shrinkage element that shrinks a volume of the pressure chamber per periodic unit period,

the second drive signal includes a second shrinkage element that shrinks the volume of the pressure chamber per unit period, and

a shrinkage step is executed in which a first period and a second period overlap, and the first shrinkage element is supplied to the first active portion in the first period, and the second shrinkage element is supplied to the second active portion in the second period.

2. The liquid discharge apparatus according to claim 1 , wherein

during executing the shrinkage step, a magnitude relationship between potentials of the first drive signal and the second drive signal is reversed.

3. The liquid discharge apparatus according to claim 1 , wherein

in the unit period, a start timing of the first shrinkage element is later than a start timing of the second shrinkage element.

4. The liquid discharge apparatus according to claim 3 , wherein

in the unit period, an end timing of the first shrinkage element is later than an end timing of the second shrinkage element.

5. The liquid discharge apparatus according to claim 1 , wherein

the first drive signal includes a first expansion element that expands the volume of the pressure chamber per unit period,

the second drive signal includes a second expansion element that expands the volume of the pressure chamber per unit period, and

an expansion step is executed in which a third period during which the first expansion element is supplied to the first active portion and a fourth period during which the second expansion element is supplied to the second active portion overlap.

6. The liquid discharge apparatus according to claim 5 , wherein

in the unit period, the expansion step is executed before the shrinkage step.

7. The liquid discharge apparatus according to claim 5 , wherein

in the unit period, the expansion step is executed after the shrinkage step.

8. The liquid discharge apparatus according to claim 7 , wherein

the first drive signal includes a first holding period that holds a voltage after the first shrinkage element,

the second drive signal includes a second holding period that holds a voltage after the second shrinkage element, and

lengths of the first holding period and the second holding period are different.

9. The liquid discharge apparatus according to claim 7 , wherein

the first drive signal and the second drive signal are signals having mutually opposite phases.

10. The liquid discharge apparatus according to claim 7 , wherein

in a standby state where liquid is not discharged from the nozzle, the second drive signal maintains a state where the volume of the pressure chamber is expanded.

11. The liquid discharge apparatus according to claim 5 , wherein

the first period and the fourth period do not overlap, and

the second period and the third period do not overlap.

12. The liquid discharge apparatus according to claim 5 , wherein

the expansion step includes a first expansion step and a second expansion step, and

in the unit period, the shrinkage step is executed between the first expansion step and the second expansion step.

13. The liquid discharge apparatus according to claim 1 , wherein

the piezoelectric element includes a third active portion that overlaps the pressure chamber at a position closer to the outer edge of the pressure chamber than the first active portion when viewed in the thickness direction of the diaphragm, and

the first active portion is located between the second active portion and the third active portion when viewed in the thickness direction of the diaphragm.

14. The liquid discharge apparatus according to claim 13 , wherein

the piezoelectric element includes a first electrode layer, a piezoelectric layer, and a second electrode layer in this order in a direction away from the diaphragm,

the piezoelectric layer and the second electrode layer are provided in common over the first active portion, the second active portion, and the third active portion, and

the first electrode layer includes a plurality of individual electrodes individually provided in the first active portion, the second active portion, and the third active portion.

15. A liquid discharge apparatus comprising:

a diaphragm that has a first surface and a second surface facing in a direction opposite to the first surface;

a pressure chamber substrate laminated on the first surface and including a partition wall partitioning a pressure chamber communicating with a nozzle for discharging liquid;

a piezoelectric element laminated on the second surface and including a first active portion that overlaps a center of the pressure chamber when viewed in a thickness direction of the diaphragm and a second active portion that overlaps the pressure chamber at a position closer to an outer edge of the pressure chamber than the first active portion; and

a drive signal generation portion that generates a first drive signal that drives the first active portion and a second drive signal that drives the second active portion, wherein

the first drive signal includes a first period during which a first potential changes to a second potential per periodic unit period,

the second drive signal includes a second period during which a third potential changes to a fourth potential per unit period, and

the first period and the second period overlap.

16. The liquid discharge apparatus according to claim 15 , wherein

in a period during which the first period and the second period overlap, a magnitude relationship between voltages of the first drive signal and the second drive signal is reversed.

17. The liquid discharge apparatus according to claim 15 , wherein

in the unit period, a start timing of the first period is later than a start timing of the second period.

18. The liquid discharge apparatus according to claim 15 , wherein

the first drive signal, per unit period, includes

a first holding period that follows the first period and holds the second potential, and

a third period that follows the first holding period and during which the second potential changes to a fifth potential,

the second drive signal, per unit period, includes

a second holding period that follows the second period and holds the fourth potential, and

a fourth period that follows the second holding period and during which the fourth potential changes to a sixth potential, and

the third period and the fourth period overlap.

19. The liquid discharge apparatus according to claim 18 , wherein

in a period during which the third period and the fourth period overlap, a magnitude relationship between potentials of the first drive signal and the second drive signal is reversed.

20. The liquid discharge apparatus according to claim 18 , wherein

lengths of the first holding period and the second holding period are different.