Liquid discharge head and liquid discharge apparatus

1. A liquid discharge head comprising:

an individual liquid chamber having a nozzle through which a liquid is discharged in a liquid discharge direction;

a piezoelectric element facing the individual liquid chamber;

a first groove adjacent to the piezoelectric element in a nozzle array direction, the first groove extending in the liquid discharge direction;

a dummy individual liquid chamber without any nozzle;

a dummy piezoelectric element facing the dummy individual liquid chamber; and

a second groove adjacent to the dummy piezoelectric element in the nozzle array direction, the second groove having a shorter length in the liquid discharge direction than the first groove.

2. The liquid discharge head according to claim 1 ,

wherein the dummy individual liquid chamber, the dummy piezoelectric element, and the second groove include a plurality of dummy individual liquid chambers, a plurality of dummy piezoelectric elements, and a plurality of second grooves, respectively,

wherein the plurality of dummy individual liquid chambers is disposed adjacent to the individual liquid chamber on a side close to an end of the liquid discharge head in the nozzle array direction, and

wherein lengths of the second grooves in the liquid discharge direction are shorter at a position farther from the individual liquid chamber.

3. The liquid discharge head according to claim 1 ,

wherein each of the second grooves is a pair of second grooves between which each of the dummy piezoelectric elements is disposed, and

wherein the second grooves in the pair have the same length.

4. The liquid discharge head according to claim 1 ,

wherein each of the second grooves is a pair of second grooves between which each of the dummy piezoelectric elements is disposed, and

wherein the second grooves in the pair have different lengths.

5. The liquid discharge head according to claim 1 ,

wherein the dummy individual liquid chamber, the dummy piezoelectric element, and the second groove include a plurality of dummy individual liquid chambers, a plurality of dummy piezoelectric elements, and a plurality of second grooves, respectively,

wherein the plurality of dummy individual liquid chambers is disposed adjacent to the individual liquid chamber on a side close to an end of the liquid discharge head in the nozzle array direction, and

wherein one of the second grooves closest to the end of the liquid discharge head has a shorter length in the liquid discharge direction than another one of the second grooves closest to the individual liquid chamber.

6. The liquid discharge head according to claim 1 , further comprising a heating device configured to adjust a temperature of the individual liquid chamber.

7. The liquid discharge head according to claim 6 , further comprising:

a nozzle substrate in which the nozzle is formed; and

a diaphragm substrate configured to pressurize the liquid in the individual liquid chamber together with the piezoelectric element,

wherein the heating device, the dummy piezoelectric element, the diaphragm substrate, the dummy individual liquid chamber, and the nozzle substrate are arranged in this order in the liquid discharge direction.

8. The liquid discharge head according to claim 7 ,

wherein the heating device and the dummy piezoelectric element are stacked in the liquid discharge direction.

9. A liquid discharge apparatus comprising:

the liquid discharge head according to claim 1 .