Piezoelectric vibrator, intrinsic frequency adjusting method of piezoelectric vibrator, piezoelectric actuator and electronic device

Abstract

A piezoelectric vibrator includes: a flat plate piezoelectric element, the piezoelectric vibrator vibrating in a mixed mode of stretching vibration that generates a displacement in a first direction within a plane of the piezoelectric element and a bending vibration that generates a displacement in a second direction orthogonal to the first direction; a vibrating member provided with the piezoelectric element and vibrated by applying voltage on the piezoelectric element; a support member provided on the vibrating member to support the vibrating member in a vibratable manner the support member being provided on an outer edge of the vibrating member at a position adjacent to anti-node other than free end of the bending vibration, the support member including a first support section extending in a direction approximately orthogonal to the first direction and a second support section extending in a direction approximately orthogonal to the direction in which the first support section extends; and a fixing portion provided on the support member to be fixed on an object on which the piezoelectric vibrator is attached.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.

FIG. 1 shows an exterior of an electronic timepiece according to an exemplary embodiment of the invention;

FIG. 2 is a plan view showing a date display device of the exemplary embodiment;

FIG. 3 is a partially enlarged illustration of FIG. 2;

FIG. 4 is an exploded perspective view showing a piezoelectric actuator of the exemplary embodiment;

FIG. 5 is a plan view showing a piezoelectric vibrator of the exemplary embodiment;

FIG. 6 is a plan view illustrating a movement of the piezoelectric vibrator of the exemplary embodiment;

FIG. 7 is a plan view illustrating a movement of the piezoelectric vibrator of the exemplary embodiment;

FIG. 8A is a graph showing a relationship between drive frequency and impedance of the piezoelectric vibrator of the exemplary embodiment;

FIG. 8B is a graph showing a relationship between drive frequency and amplitude of longitudinal vibration and bending vibration of the piezoelectric vibrator of the exemplary embodiment; and

FIG. 9 is a plan view showing a piezoelectric actuator according to a modification of the invention.

Claims

1. A piezoelectric vibrator, comprising: a flat plate piezoelectric element, the piezoelectric vibrator vibrating in a mixed mode of stretching vibration that generates a displacement in a first direction within a plane of the piezoelectric element and a bending vibration that generates a displacement in a second direction orthogonal to the first direction;a vibrating member provided with the piezoelectric element and vibrated by applying voltage on the piezoelectric element;a support member provided on the vibrating member to support the vibrating member in a vibratable manner, the support member being provided on an outer edge of the vibrating member at a position adjacent to anti-node other than free end of the bending vibration, the support member including a first support section extending in a direction approximately orthogonal to the first direction and a second support section extending in a direction approximately orthogonal to the direction in which the first support section extends; anda fixing portion provided on the support member to be fixed on an object on which the piezoelectric vibrator is attached.

2. The piezoelectric vibrator according to claim 1, wherein the first support section includes a pair of first support sections extending substantially in parallel from positions adjacent to different anti-nodes of a plurality of anti-nodes of the bending vibration, andthe second support connects the pair of first support sections.

3. The piezoelectric vibrator according to claim 1, wherein the fixing portion is fixed on the object along a nodal line of the stretching vibration of the vibrating member.

4. The piezoelectric vibrator according to claim 1, wherein the first support section includes portions having different rigidity, the portions including a first rigid portion adjacent to the vibrating member and a second rigid portion having less rigidity than the first rigid portion.

5. The piezoelectric vibrator according to claim 1, wherein the second support section includes portions having different rigidity, the portions including a first rigid portion adjacent to the fixing portion and a second rigid portion having less rigidity than the first rigid portion.

6. The piezoelectric vibrator according to claim 1, wherein the vibrating member is formed by laminating a reinforcing plate on the piezoelectric element, andthe first and the second support sections are integrally provided on the reinforcing plate.

7. An intrinsic frequency adjusting method, comprising: providing a piezoelectric vibrator, the piezoelectric vibrator including: a flat plate piezoelectric element, the piezoelectric vibrator vibrating in a mixed mode of stretching vibration that generates a displacement in a first direction within a plane of the piezoelectric element and a bending vibration that generates a displacement in a second direction orthogonal to the first direction; a vibrating member provided with the piezoelectric element and vibrated by applying voltage on the piezoelectric element; a support member provided on the vibrating member to support the vibrating member in a vibratable manner, the support member being provided on an outer edge of the vibrating member at a position adjacent to anti-node other than free end of the bending vibration, the support member including a first support section extending in a direction approximately orthogonal to the first direction and a second support section extending in a direction approximately orthogonal to the direction in which the first support section extends; and a fixing portion provided on the support member to be fixed on an object on which the piezoelectric vibrator is attached; andchanging a dimension or a shape of at least one of the first support section and the second support section to adjust the intrinsic frequency of the piezoelectric vibrator.

8. The intrinsic frequency adjusting method according to claim 7, wherein, in adjusting the intrinsic frequency, difference between the intrinsic frequency of the stretching vibration and intrinsic frequency of the bending vibration is adjusted by altering the dimension or the shape of one of the first support section and the second support section.

9. A piezoelectric actuator, comprising: a piezoelectric vibrator that includes: a flat plate piezoelectric element, the piezoelectric vibrator vibrating in a mixed mode of stretching vibration that generates a displacement in a first direction within a plane of the piezoelectric element and a bending vibration that generates a displacement in a second direction orthogonal to the first direction; a vibrating member provided with the piezoelectric element and vibrated by applying voltage on the piezoelectric element, a free end of the stretching vibration of the vibrating member in the displacing direction abutting on a body to which the vibration of the piezoelectric vibrator is transmitted; a support member provided on the vibrating member to support the vibrating member in a vibratable manner, the support member being provided on an outer edge of the vibrating member at a position adjacent to anti-node other than free end of the bending vibration, the support member including a first support section extending in a direction approximately orthogonal to the first direction and a second support section extending in a direction approximately orthogonal to the direction in which the first support section extends; and a fixing portion provided on the support member to be fixed on an object on which the piezoelectric vibrator is attached.

10. The piezoelectric actuator according to claim 9, wherein the support member includes a plurality of support members that are disposed substantially axisymmetrically with respect to a displacing direction of the stretching vibration of the vibrating member, anda vibration locus of the free end is switched substantially axisymmetrically with respect to the displacing direction of the stretching vibration of the vibrating member.

11. An electronic device, comprising: a piezoelectric vibrator that includes a flat plate piezoelectric element, the piezoelectric vibrator vibrating in a mixed mode of stretching vibration that generates a displacement in a first direction within a plane of the piezoelectric element and a bending vibration that generates a displacement in a second direction orthogonal to the first direction; a vibrating member provided with the piezoelectric element and vibrated by applying voltage on the piezoelectric element; a support member provided on the vibrating member to support the vibrating member in a vibratable manner, the support member being provided on an outer edge of the vibrating member at a position adjacent to anti-node other than free end of the bending vibration, the support member including a first support section extending in a direction approximately orthogonal to the first direction and a second support section extending in a direction approximately orthogonal to the direction in which the first support section extends; and a fixing portion provided on the support member to be fixed on an object on which the piezoelectric vibrator is attached.

12. The electronic device according to claim 11, wherein the electronic device is a timepiece including a timer and a time information display that displays information timed by the timer.