Vibrating element having meandering shape, and optical reflection element
A vibrating element having a meandering shape includes a vibrating beam and a piezoelectric actuator provided on the vibrating beam. The vibrating beam has a meandering-shape substantially formed into the plurality of continuous turned-down shapes. The vibrating beam includes the plurality of turned-down units and the plurality of coupling units coupled to the turned-down units, and the coupling units and the turned-down units are alternately disposed. The piezoelectric actuator includes a lower electrode provided on the vibrating beam, a piezoelectric film provided on the lower electrode, and an upper electrode provided on the piezoelectric film. A non-existence region where the piezoelectric film does not exist is provided in at least one of a neighborhood of a midpoint of an inner circumference of each of the turned-down units and a neighborhood of a curvature changing point in which a curvature of the inner circumference of each of the turned-down shapes changes.
1. A meandering-shaped vibrating element comprising:
a vibrating beam having a meandering shape including:
a plurality of turning portions, and
a plurality of coupling portions having straight shapes that are parallel with each other and are coupled to the plurality of turning portions such that the coupling portions and the plurality of turning portions are connected alternately; and
a piezoelectric actuator including:
a lower electrode provided on the vibrating beam,
a piezoelectric film provided on the lower electrode, and
an upper electrode provided on the piezoelectric film,
wherein each one turning portion out of the plurality of turning portions and respective pair of coupling portions out of the plurality of coupling portions connected to the each one turning portion substantially form a U-shape having an inner circumference and an outer circumference,
wherein each of the plurality of turning portions includes a non-existence region where the upper electrode does not exist and an existence region where the upper electrode exists,
wherein the non-existence region includes the inner circumference of the U-shape, and is located away from the outer circumference of the U-shape, and
wherein the existence region is closer to the outer circumference of the U-shape than the non-existence region.
2. The meandering-shaped vibrating element according to claim 1 ,
wherein each of the plurality of coupling portions and each of the plurality of turning portions are connected at a right angle.
3. The meandering-shaped vibrating element according to claim 1 ,
wherein the piezoelectric film does not exist in alternate ones of the plurality of coupling portions.
4. An optical reflection element comprising:
the meandering-shaped vibrating element according to claim 3 ;
a fixed unit to which one end of the meandering-shaped vibrating element is connected; and
a mirror unit that is turned by the meandering-shaped vibrating element.
5. The meandering-shaped vibrating element according to claim 1 , wherein the non-existence region of each of the plurality of turning portions includes a curvature changing point at which a curvature of the inner circumference of the U-shape changes.
6. The meandering-shaped vibrating element according to claim 5 , wherein
each of the plurality of turning portions and each of the plurality of coupling portions are connected at a curvature changing point.
7. The meandering-shaped vibrating element according to claim 1 ,
wherein the piezoelectric film has a surface having the upper electrode thereon, and
wherein the surface of the piezoelectric film includes a portion located in the non-existence region of each of the plurality of turning portions.
8. The meandering-shaped vibrating element according to claim 7 , wherein
each of the plurality of turning portions and each of the plurality of coupling portions are connected at a curvature changing point.
9. A meandering-shaped vibrating element comprising:
a vibrating beam having a meandering shape including:
a plurality of turning portions, and
a plurality of coupling portions having straight shapes that are parallel with each other and are coupled to the plurality of turning portions such that the coupling portions and the plurality of turning portions are connected alternately; and
a piezoelectric actuator including:
a lower electrode provided on the vibrating beam,
a piezoelectric film provided on the lower electrode, and
an upper electrode provided on the piezoelectric film,
wherein each one turning portion out of the plurality of turning portions and respective pair of coupling portions of the plurality of coupling portions connected to the each one turning portion substantially form a U-shape having an inner circumference and an outer circumference,
wherein each of the plurality of turning portions includes a non-existence region where the piezoelectric film does not exist and an existence region where the piezoelectric film exists,
wherein the non-existence region includes the inner circumference of the U-shape, and is located away from the outer circumference of the U-shape, and
wherein the existence region is closer to the outer circumference of the U-shape than the non-existence region.
10. The meandering-shaped vibrating element according to claim 9 , wherein the upper electrode does not exist in the non-existence region.
11. The meandering-shaped vibrating element according to claim 9 ,
wherein each of the plurality of coupling portions and each of the plurality of turning portions are connected at a right angle.
12. The meandering-shaped vibrating element to claim 9 ,
wherein the piezoelectric film does not exist in alternate ones of the plurality of coupling portions.
13. An optical reflection element comprising:
the meandering-shaped vibrating element according to claim 12 ;
a fixed unit to which one end of the meandering-shaped vibrating element is connected; and
a mirror unit that is turned by the meandering-shaped vibrating element.
14. The meandering-shaped vibrating element according to claim 9 , wherein the non-existence region of each of the plurality of turning portions includes a curvature changing point at which a curvature of the inner circumference of the U-shape changes.