JP5874406B2 - Piezoelectric actuator and electronic device including the same - Google Patents

Description

  The present invention relates to a piezoelectric actuator including a plate-like vibrating body having a piezoelectric element and a moving body that moves by vibration of the vibrating body, and an electronic device including the piezoelectric actuator.

  Conventionally, as described in, for example, Patent Document 1, a piezoelectric actuator is configured to include a vibrating body having a piezoelectric element and a moving body that comes into contact with the vibrating body, and vibrates due to a reverse piezoelectric effect. The driving force is obtained by moving the moving body. In such a piezoelectric actuator, a necessary driving force is obtained by biasing the vibrating body to the moving body or biasing the moving body to the vibrating body. The urging means includes means for generating a pressing force such as a coil spring and a leaf spring and means for moving the vibrating body or the moving body itself.

JP-A-7-184382

In the piezoelectric actuator described in Patent Document 1, when an impact is applied, since the vibrating body and the moving body are jointed, an excessive force is applied to the joint part and the piezoelectric element may be destroyed. In particular, when used in a portable electronic device, it is often accidentally dropped, but the weight of the vibrating body and the whole means for moving the vibrating body is added to the moving body.
The impact due to the drop is 1m drop on the vinyl tile, and if the collision time is t = 0.0001 sec, the impact force F is
F = m√ (2gh) / t
m: mass, h: drop height, g: acceleration of gravity, and a force of 4.52 kgf is applied at a weight of 1 gf.
Accordingly, an object of the present invention is to prevent the piezoelectric actuator from being broken due to the impact of dropping the vibrating body.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A piezoelectric actuator according to this application example includes a plate-like vibrating body having a piezoelectric element, a moving body that moves by vibration of the vibrating body, a holding member that holds the moving body, and the holding member And a movable bearing movable on one axis side for fixing the movable body shaft and the holding member.

  According to this application example, the impact is mitigated by the movement of the movable bearing movable toward the one axis side due to the impact at the time of dropping, thereby having an effect of preventing the vibration body from being destroyed.

  Application Example 2 In the piezoelectric actuator according to the application example described above, a spring is attached to the movable bearing, and the bearing is normally fixed to one side by a spring force.

  According to this application example, the bearing is normally fixed to one side by a spring force, and thus the moving body can be moved.

  Application Example 3 In the piezoelectric actuator according to the application example described above, the movable bearing moves in a direction in which the distance from the vibrating body is increased.

  According to this application example, since the movable bearing moves in a direction away from the vibrating body, when a force from the vibrating body is applied due to an impact caused by dropping, the force is released. This can prevent destruction due to falling.

  Application Example 4 In the piezoelectric actuator according to the application example described above, the movable bearing is coaxial with a bearing on the opposite side of the movable body axis.

  According to this application example, since the movable bearing is coaxial with the bearing on the opposite side of the moving body axis, the rotation on the moving body axis is not hindered and can be rotated.

  Application Example 5 In the piezoelectric actuator according to the application example described above, an orifice is used for the bearing on the opposite side.

  According to this application example, when the movable body bearing is moved by a spring and the movable body shaft is moved, the opposite bearing is a straight bearing, but the shaft is twisted, but an orifice is used. By this, it is possible to eliminate twisting even if the shaft is inclined.

  Application Example 6 In the piezoelectric actuator according to the application example described above, the movable bearing moves the movable body shaft when an impact is applied.

  According to this application example, since the movable body shaft moves when an impact is applied to the movable bearing, normally, the movable shaft remains fixed at a fixed position, and thus the movable body shaft can rotate without load.

  Application Example 7 An electronic apparatus according to this application example includes the piezoelectric actuator described above.

  According to this application example, an effect similar to that of the above-described piezoelectric actuator can be obtained, whereby an electronic device with high operation reliability can be configured and manufactured. Examples of such electronic devices include watches such as watches and cameras.

FIG. 3 is a plan view showing the piezoelectric actuator according to the first embodiment. FIG. 3 is a cross-sectional view illustrating the piezoelectric actuator according to the first embodiment. FIG. 3 is a normal position diagram illustrating the movable bearing according to the first embodiment. Sectional drawing which shows the time of the movable bearing movement by the impact which concerns on Embodiment 1. FIG. The impact position figure which shows the movable bearing which concerns on Embodiment 1. FIG. FIG. 6 is a plan view showing a piezoelectric actuator according to a second embodiment. The back of the top view which shows the piezoelectric actuator which concerns on Embodiment 2. FIG. FIG. 6 is a plan view showing an electronic apparatus according to a third embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale of each layer and each member is made different from the actual scale so that each layer and each member can be recognized.

(Embodiment 1)
FIG. 1 is a plan view showing the piezoelectric actuator according to the first embodiment. FIG. 2 is a cross-sectional view showing the piezoelectric actuator.
First, a schematic configuration of the piezoelectric actuator according to the first embodiment will be described.

  The piezoelectric actuator 100 includes a plate-like vibrating body 21 having a piezoelectric element, a moving body 51 that moves due to the vibration of the vibrating body 21, a holding member 56 that holds the moving body 51, a moving body shaft 52, and a holding member 56. And a movable bearing 55 that is movable on one axis side.

  The moving body 51 is formed in an annular shape and is made of ceramic, stainless steel, iron, aluminum, or other materials. An annular moving body shaft 52 is press-fitted on the inner peripheral side of the moving body 51. The moving body shaft 52 is rotatably fitted to a hole 53 fixed to the holding member 56. A pinion may be formed on the moving body shaft 52, and a deceleration and a speed increasing wheel train can be configured.

  The drive mechanism 20 includes a vibrating body 21 that vibrates entirely by the piezoelectric element 22, a slider 26 to which an arm portion 25 provided on the vibrating body 21 is attached, and an attachment member 10 to which the slider 26 is attached. Yes. The drive mechanism 20 is a so-called piezoelectric actuator that vibrates when a voltage having a predetermined frequency is applied to the piezoelectric element 22 of the vibrating body 21 by a drive circuit (not shown).

  The vibrating body 21 includes a reinforcing plate 23 formed in a substantially rectangular flat plate shape, and flat plate-shaped piezoelectric elements 22 provided on both front and back surfaces of the reinforcing plate 23. The reinforcing plate 23 is made of stainless steel or other material and has a substantially rectangular flat plate shape.

  The support member 28 includes two springs 29 that can expand and contract, and is attached to the attachment member 10 by a single screw 30. The spring 29 is in contact with the back surface of the slider 26 and presses and biases the convex portion 24 of the vibrating body 21 against the side surface 57 of the moving body 51. Here, the material of the piezoelectric element 22 is not particularly limited, and various materials such as lead zirconate titanate (PZT), crystal, and lithium niobate can be used. In addition, a plurality of electrodes (5 locations on one side in this embodiment) 22A, 22B, and 22C are formed on both surfaces of the piezoelectric element 22. These electrodes 22A, 22B, and 22C are electrically connected to the drive circuit.

  When a voltage having a predetermined frequency is applied to the piezoelectric element 22, the entire vibrating body 21 vibrates due to excitation by the piezoelectric element 22. This vibration is generated in a state where the longitudinal vibration that expands and contracts along the longitudinal direction of the vibrating body 21 and the bending vibration that is bent in the plane of the vibrating body 21 are combined, and the convex portion 24 formed on the reinforcing plate 23 has an elliptical orbit. Vibrates like drawing. And the vibration which generate | occur | produced in the convex part 24 is transmitted to the part contact | abutted with the side surface 57 of the mobile body 51, and the mobile body 51 rotates.

  Further, in FIG. 1, when a voltage is applied to the electrodes 22A, 22B, and 22C of the piezoelectric element 22, the rotation direction of the moving body 51 can be arbitrarily selected by appropriately selecting the application electrode. That is, in addition to the center electrode 22A of the piezoelectric element 22, when the pair of electrodes 22B on one diagonal line is selected and when the pair of electrodes 22C on the other diagonal line are selected, the moving body 51 The direction of rotation is reversed.

A moving body shaft 52 is held by a hole 53 fixed to a holding member 56 that holds the moving body 51. A movable bearing 55 having a hole 53 fixed to the spring member 54 is provided on one axis side for fixing the moving body shaft 52, and the hole 53 is fixed on the other axis side.
As shown in FIG. 2, the movable bearing 55 has two hole stones on the same axis at the normal time when no impact is applied.

  FIG. 3 is a normal position diagram illustrating the movable bearing 55 according to the first embodiment. Specifically, it is a normal position diagram showing the movable bearing 55 to which no impact is applied. FIG. 4 is a cross-sectional view showing the movable bearing 55 moving due to an impact according to the first embodiment. FIG. 5 is an impact position diagram illustrating the movable bearing 55 according to the first embodiment. At the time of impact, the movable bearing 55 moves to release the impact. Further, although the shaft is displaced due to the impact, it is indicated that the shaft is not twisted even if the shaft is inclined by the orifice of the hole 53.

As described above, according to the piezoelectric actuator 100 according to the present embodiment, the following effects can be obtained.
When an impact is applied due to falling onto a vinyl tile or the like, the piezoelectric element 22 and the movable body 51 are prevented from being destroyed due to the weight of the slider 26 and the piezoelectric element 22 being applied to the movable body 51.

(Embodiment 2)
FIG. 6 is a plan view showing the piezoelectric actuator 100 according to the second embodiment. FIG. 7 is a back view of the plan view showing the piezoelectric actuator 100.
In addition, about the component same as Embodiment 1, the same number is used and the overlapping description is abbreviate | omitted.
First, a schematic configuration of the piezoelectric actuator according to the second embodiment will be described.

  The piezoelectric actuator 100 includes a plate-like vibrating body 21 having a piezoelectric element, a moving body 51 that moves due to the vibration of the vibrating body 21, a holding member 56 that holds the moving body 51, a moving body shaft 52, and a holding member 56. And a movable bearing 55 that is movable on one axis side.

  The moving body 51 is formed in an annular shape and is made of ceramic, stainless steel, iron, aluminum, or other materials. An annular moving body shaft 52 is press-fitted on the inner peripheral side of the moving body 51. The moving body shaft 52 is rotatably fitted to a hole 53 fixed to the holding member 56. A pinion may be formed on the moving body shaft 52, and a deceleration and a speed increasing wheel train can be configured.

  The holding member 56 is formed to be rotatable about the rotation shaft 80. The rotating shaft 80 is guided to the mounting member 10 by a bearing such as a bearing and can freely rotate.

  The drive mechanism 20 includes a vibrating body 21 that vibrates entirely by the piezoelectric element 22, a fixed base 81 to which the arm portion 25 provided on the vibrating body 21 is attached, and an attachment member 10 to which the fixed base 81 is attached. It is a so-called piezoelectric actuator. The drive mechanism 20 includes a drive circuit (not shown) that vibrates the vibrating body 21 by applying a voltage having a predetermined frequency to the piezoelectric element 22 of the vibrating body 21.

  The vibrating body 21 includes a reinforcing plate 23 formed in a substantially rectangular flat plate shape and the flat plate-like piezoelectric elements 22 provided on both the front and back surfaces of the reinforcing plate 23. The reinforcing plate 23 is made of stainless steel or other material and has a substantially rectangular flat plate shape. Further, a convex portion 24 is formed at one end portion in the length direction of the reinforcing plate 23, and the convex portion 24 is in contact with the side surface 57 of the moving body 51. The vibrating body 21 is fixed to the fixed base 81 with screws 27. The fixed base 81 is attached to the mounting member 10.

  The holding member 56 and the fixed base 81 are provided with a spring 29 that can be expanded and contracted, and are attached by two spring fixing pins 82. The spring 29 applies a tensile force between the holding member 56 and the fixed base 81, and presses and biases the convex portion 24 of the vibrating body 21 against the side surface 57 of the moving body 51. Here, the material of the piezoelectric element 22 is not particularly limited, and various materials such as lead zirconate titanate (PZT), crystal, and lithium niobate can be used.

  The vibrating body 21 is formed in a substantially rectangular plate shape. When the length of the long side of the piezoelectric element is 1, the length of the short side is 0.274 or more, and primary longitudinal vibration and secondary bending are performed. The vibration ratio to the vibration is set such that the ratio of the resonance frequency of the secondary bending vibration to the resonance frequency of the primary longitudinal vibration is greater than 1.00 and less than 1.03. desirable.

  Since the resonance frequencies of the primary longitudinal vibration and the secondary bending vibration are close to each other, when a voltage having a predetermined frequency is applied to the piezoelectric element 22 near these resonance frequencies, the primary longitudinal vibration and the secondary bending vibration are generated. At the same time, it tends to appear, and the entire vibrator 21 vibrates due to excitation by the piezoelectric element 22. This vibration is generated in a state where the longitudinal vibration that expands and contracts along the longitudinal direction of the vibrating body 21 and the bending vibration that is bent in the plane of the vibrating body 21 are combined, and the convex portion 24 formed on the reinforcing plate 23 has an elliptical orbit. Vibrates like drawing. And the vibration which generate | occur | produced in the convex part 24 is transmitted to the part contact | abutted with the side surface 57 of the mobile body 51, and the mobile body 51 rotates.

  A moving body shaft 52 is held by a hole 53 fixed to a holding member 56 that holds the moving body 51. A movable bearing 55 having a hole 53 fixed to the spring member 54 is provided on one axis side for fixing the moving body shaft 52, and the hole 53 is fixed on the other axis side.

In the second embodiment, as in the case of the actual machine form 1, the movable bearing 55 has two hole stones on the same axis at the normal time when no impact is applied as shown in FIG.
As shown in FIGS. 3 to 5, the impact is released by moving the movable bearing 55 at the time of impact. Further, although the shaft is displaced due to the impact, it is indicated that the shaft is not twisted even if the shaft is inclined by the orifice of the hole 53. FIG. 5 is an impact position diagram illustrating the movable bearing according to the second embodiment.

As described above, according to the piezoelectric actuator 100 according to the present embodiment, the following effects can be obtained.
When an impact is applied due to falling onto a vinyl tile or the like, the piezoelectric element 22 and the moving body 51 are prevented from being destroyed due to the weight of the piezoelectric element 22 and the like being applied to the moving body 51.

(Embodiment 3)
FIG. 8 is a plan view showing an electronic apparatus (clock) according to the third embodiment.
First, a schematic configuration of the electronic device according to the third embodiment will be described.

  The electronic device 200 includes a plate-like vibrating body 21 having a piezoelectric element, a moving body 51 that moves due to the vibration of the vibrating body 21, a holding member 56 that holds the moving body 51, a moving body shaft 52, and a holding member 56. And a movable bearing 55 that is movable on one axis side.

  The moving body 51 is formed in an annular shape and is made of ceramic, stainless steel, iron, aluminum, or other materials. An annular moving body shaft 52 is press-fitted on the inner peripheral side of the moving body 51. The moving body shaft 52 is rotatably fitted to a hole 53 fixed to the holding member 56. A pinion is formed on the moving body shaft 52 and is combined with the gear of the fourth wheel & pinion 110. The pinion of the fourth wheel 110 is combined with the gear of the third wheel 111. The pinion of the third wheel 111 is combined with the gear of the second wheel 112 on the same axis as the fourth wheel 110 to constitute a reduction wheel train.

  A second hand is attached to the tip of the fourth wheel 110 and an hour hand is attached to the tip of the second wheel 112 to constitute a timepiece.

  The drive mechanism 20 includes a vibrating body 21 that vibrates entirely by the piezoelectric element 22, a slider 26 to which an arm portion 25 provided on the vibrating body 21 is attached, and an attachment member 10 to which the slider 26 is attached. Yes. The drive mechanism 20 is a so-called piezoelectric actuator that vibrates when a voltage having a predetermined frequency is applied to the piezoelectric element 22 of the vibrating body 21 by a drive circuit (not shown).

  The vibrating body 21 includes a reinforcing plate 23 formed in a substantially rectangular flat plate shape, and flat plate-shaped piezoelectric elements 22 provided on both front and back surfaces of the reinforcing plate 23. The reinforcing plate 23 is made of stainless steel or other material and has a substantially rectangular flat plate shape.

  The support member 28 includes a single elastic spring 29 and is directly attached to the attachment member 10. The spring 29 is in contact with the back surface of the slider 26 and presses and biases the convex portion 24 of the vibrating body 21 against the side surface 57 of the moving body 51.

  When a voltage having a predetermined frequency is applied to the piezoelectric element 22, the entire vibrating body 21 vibrates due to excitation by the piezoelectric element 22. This vibration is generated in a state where the longitudinal vibration that expands and contracts along the longitudinal direction of the vibrating body 21 and the bending vibration that is bent in the plane of the vibrating body 21 are combined, and the convex portion 24 formed on the reinforcing plate 23 has an elliptical orbit. Vibrates like drawing. And the vibration which generate | occur | produced in the convex part 24 is transmitted to the part contact | abutted with the side surface 57 of the mobile body 51, the mobile body 51 rotates, and a timepiece wheel train rotates.

A moving body shaft 52 is held by a hole 53 fixed to a holding member 56 that holds the moving body 51. A movable bearing 55 having a hole 53 fixed to the spring member 54 is provided on one axis side for fixing the moving body shaft 52, and the hole 53 is fixed on the other axis side.
As shown in FIG. 2, the movable bearing 55 has two hole stones on the same axis at the normal time when no impact is applied.

As described above, according to the electronic device 200 according to the present embodiment, the following effects can be obtained.
When an impact is applied due to falling onto a vinyl tile or the like, the weight of the slider 26 and the piezoelectric element 22 and the like is applied to the moving body 51, thereby preventing the piezoelectric element 22 and the moving body 51 from being destroyed. Failure is prevented.

  DESCRIPTION OF SYMBOLS 10 ... Mounting member 20 ... Drive mechanism 21 ... Vibrating body 22 ... Piezoelectric element 22A, 22B, 22C ... Electrode 23 ... Reinforcement plate 24 ... Convex part 25 ... Arm part 26 ... Slider 27 ... Screw 28 ... Supporting member 29 ... Spring 51 ... Moving body 52 ... Moving body shaft 53 ... Hole stone 54 ... Spring member 55 ... Movable bearing 56 ... Holding member 57 ... Side surface 80 ... Rotating shaft 81 ... Fixed base 82 ... Spring fixing pin 100 ... Piezoelectric actuator 110 ... Fourth wheel 111 ... Third car 112 ... Second car 200 ... Electronic equipment.

Claims (7)

A plate-like vibrating body having a piezoelectric element;
A moving body that moves by vibration of the vibrating body;
A holding member for holding the moving body;
A moving body shaft attached to the holding member;
A movable bearing that is provided on the one-axis side that fixes the movable body axis and the holding member, and is movable in a direction intersecting the direction along the movable body axis;
A piezoelectric actuator characterized by comprising: The piezoelectric actuator according to claim 1, wherein
A piezoelectric actuator, wherein a spring is attached to the movable bearing, and the bearing is normally fixed to one side by a spring force. The piezoelectric actuator according to claim 1 or 2,
The piezoelectric actuator is characterized in that the movable bearing moves in a direction away from the vibrating body. In the piezoelectric actuator as described in any one of Claims 1-3,
The piezoelectric actuator is characterized in that the movable bearing is coaxial with a bearing opposite to the moving body axis. The piezoelectric actuator according to claim 4, wherein
A piezoelectric actuator characterized in that an orifice is used for the bearing on the opposite side. In the piezoelectric actuator according to any one of claims 1 to 5,
The movable actuator is a piezoelectric actuator characterized in that the moving body axis moves when an impact is applied.   An electronic apparatus comprising the piezoelectric actuator according to claim 1.

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