Loudspeakers

1. A loudspeaker, comprising: a casing, a driving unit, and a vibration unit, wherein:

the driving unit is fixed to the casing and is drivingly connected with the vibration unit;

the driving unit includes a plurality of driving beams, each of the plurality of driving beams includes a fixed region and an overhanging region, each of the plurality of driving beams is connected with the casing through its fixed region, and each of the plurality of driving beams is connected with the vibration unit through its overhanging region; and

each of the plurality of driving beams includes a substrate layer, a first electrode layer, a piezoelectric layer, a second electrode layer, and a reinforcement layer stacked in a vibration direction of the vibration unit, and a ratio of a thickness of the substrate layer to a thickness of the piezoelectric layer is in a range of 0 to 2, wherein each of the plurality of driving beams is connected with a vibration transmission unit, respectively, the vibration transmission unit is connected with the vibration unit, and each of the plurality of driving beams transmits vibration to the vibration unit through the vibration transmission unit.

2. The loudspeaker of claim 1 , wherein,

for each of the plurality of driving beams,

in a direction extending from the fixed region to the overhanging region, the overhanging region has a length dimension;

in the vibration direction of the vibration unit, the overhanging region has a thickness dimension; and

a square root of a ratio of the thickness dimension of the overhanging region to a square of the length dimension of the overhanging region is in a range of 0.01 to 0.3.

3. The loudspeaker of claim 1 , wherein each of the plurality of driving beams includes a piezoelectric structure and one or more reinforcement layers stacked in the vibration direction of the vibration unit, and a slot structure is provided on a reinforcement layer that is furthest away from the piezoelectric structure; wherein

the slot structure includes a plurality of slots in a direction extending from the fixed region to the overhanging region, and a dimension of a slot that is proximate to the fixed region is greater than a dimension of a slot that is further away from the fixed region; or

the slot structure includes a plurality of reinforcement members spaced apart in a direction extending from the fixed region to the overhanging region, a slot is provided between any two adjacent reinforcement members, and a width of a reinforcement member that is further away from the fixed region is greater than a width of a reinforcement member that is proximate to the fixed region.

4. The loudspeaker of claim 1 , wherein the driving unit includes two sets of driving beams disposed on opposite sides of the casing, each of the two sets of driving beams includes one or more driving beams, and a shape of the one or more driving beams includes a rectangle, a trapezoid, or a rounded chamfered corner.

5. The loudspeaker of claim 4 , wherein the driving unit further includes two sets of driving beams located on another pair of opposite sides of the casing.

6. The loudspeaker of claim 5 , wherein the vibration transmission unit includes a ring structure, and each set of the driving beams is connected with a different region of the vibration transmission unit.

7. The loudspeaker of claim 6 , wherein a second driving beam is connected with the vibration transmission unit and is indirectly connected with the casing, the vibration unit further includes a mass element, one end of the second driving beam away from the vibration transmission unit is directly connected with the mass element; or the end of the second driving beam away from the vibration transmission unit is connected with the mass element through a coupled elastic structure.

8. The loudspeaker of claim 6 , wherein the vibration unit further includes a mass element, and the vibration transmission unit is connected with the mass element through a coupled elastic structure.

9. The loudspeaker of claim 4 , wherein the two sets of driving beams extend in a staggered type, the vibration transmission unit includes a folded structure, and each set of the two sets of driving beams is connected with a different region of the vibration transmission unit.

10. The loudspeaker of claim 9 , wherein each set of the two sets of driving beams is directly connected with the vibration transmission unit; or each set of the two sets of driving beams is connected with the vibration transmission unit through a coupled elastic structure.

11. The loudspeaker of claim 4 , wherein each set of the two sets of driving beams includes one driving beam with a bent structure, and each driving beam with a bent structure has an end away from its fixed region, two ends of the two driving beams each with a bent structure are coupled to a same vibration transmission unit.

12. The loudspeaker of claim 1 , wherein each of the plurality of driving beams is stacked in a different region of the vibration unit.

13. The loudspeaker of claim 12 , wherein the vibration unit includes a suspension region not covered by the driving beams, in a direction extending from the fixed region to the overhanging region, the overhanging region has a length dimension, a sum of a length of each of the driving beams and half of a length of the suspension region is defined as a first parameter, and a ratio of the length dimension of the overhanging region to the first parameter is in a range of 0.7 to 1; or

in a direction perpendicular to a direction extending from the fixed region to the overhanging region, a ratio of a width dimension of the overhanging region to a width dimension of the suspension region is in a range of 0.5 to 0.95.

14. The loudspeaker of claim 12 , wherein different driving beams are connected with each other through a coupled elastic structure.

15. The loudspeaker of claim 1 , wherein the overhanging region of each of the plurality of driving beams includes a non-electrode-covered region, at least a portion of the non-electrode-covered region is located at an end portion of the driving beam away from the fixed region.

16. The loudspeaker of claim 15 , wherein the overhanging region of each of the plurality of driving beams includes an electrode-covered region, in a direction extending from the fixed region to the overhanging region, a ratio of a length dimension of the electrode-covered region to a length dimension of the overhanging region is in a range of 0.3 to 1; or a ratio of an area of the electrode-covered region to an area of the overhanging region is in a range of 0.3 to 1.

17. The loudspeaker of claim 1 , wherein each of the plurality of driving beams is connected with the vibration transmission unit through a coupled elastic structure.

18. The loudspeaker of claim 1 , wherein the vibration unit includes a movable region, the movable region is provided with a reinforcement structure, at least a portion of the reinforcement structure covers the movable region, and a projection of a center of the reinforcement structure coincides with a projection of a center of the movable region in the vibration direction of the vibration unit.

19. The loudspeaker of claim 18 , wherein the reinforcement structure is provided with a hollow structure; or the reinforcement structure is provided with a notch along a periphery of the reinforcement structure.