Lens array and display device

1. A lens array comprising a plurality of lens elements, wherein

each of the plurality of lens elements comprises:

a boundary surface of two layers with different refractive indices, and

an actuator configured to deform the boundary surface, wherein

the actuator comprises a first electrode, a second electrode, and a piezoelectric element that deforms in response to a voltage between the first electrode and the second electrode, and

the boundary surface deforms together with the piezoelectric element.

2. The lens array of claim 1 , wherein

the first electrode is superposed on a part of the piezoelectric element, and

in a case where a voltage is applied between the first electrode and the second electrode, the piezoelectric element deforms convexly with its top at a portion where the first electrode and the piezoelectric element superpose, or concavely with its bottom at a portion where the first electrode and the piezoelectric element superpose.

3. The lens array of claim 2 , wherein the first electrode has a linear shape that is superposed on a central part of the lens element in a first direction and extends in a second direction intersecting the first direction.

4. A lens array comprising a plurality of lens elements, wherein

each of the plurality of lens elements comprises:

a boundary surface of two layers with different refractive indices; and

an actuator configured to deform the boundary surface, wherein

the actuator comprises a shape memory alloy that deforms due to heat generated when energized, and

the boundary surface deforms together with the shape memory alloy.

5. The lens array of claim 4 , wherein

the shape memory alloy has a linear shape extending in a first direction, and

the actuator includes a plurality of said shape memory alloys aligned in a second direction intersecting the first direction.