Abstract:
A piezoelectric motor includes: a base; first and second piezoelectric elements that are provided symmetrically on the base to face with each other, the first and second piezoelectric elements actuating in opposite directions; first and second displacement enlarging mechanisms that respectively enlarge actuating displacements of the first and second piezoelectric elements through first and second levers that rotate around first and second fulcrums fixed to the base; first and second leaf springs that are respectively coupled to action points of the first and second levers at one ends thereof; and an actuating portion that is coupled to the other ends of the first and second leaf springs and swings in accordance with actuation of the first and the second piezoelectric elements, the actuating portion being urged against a driven member to actuate the driven member with a frictional force.

Description:
RELATED APPLICATION(S) 
       [0001]    The present disclosure relates to the subject matter contained in Japanese Patent Application No. 2007-201080 filed on Aug. 1, 2007, which is incorporated herein by reference in its entirety. 
       FIELD 
       [0002]    The present invention relates to a piezoelectric motor and a camera device utilizing the piezoelectric motor, which actuates a driven member by a frictional force using a piezoelectric element. 
       BACKGROUND 
       [0003]    Conventionally, in the field of an actuator controller system having a multi-degree-of-freedom in rotation, which is used for controlling orientation of a monitoring camera and for a joint mechanism of a robot, there has widely been used an actuator mechanism or a motor system with a configuration in which a plurality of single-degree-of-freedom type motors are serially stacked in multistage. From a viewpoint of a reduction in a size and an enhancement in accuracy, in some cases, there is employed a multi-degree-of-freedom type actuator mechanism or a multi-degree-of-freedom type motor system which has a support system using a gimbal mechanism or a joint mechanism and an actuator system using an electromagnetic motor provided separately form the support system. However, in a conventional actuator mechanism or motor system, the serial multistage stacking structure of the single-degree-of-freedom type motors serves as a basic configuration irrespective of the presence of the gimbal mechanism or the joint mechanism. Therefore, the conventional actuator controller system has a difficulty in simplifying its configuration and in reducing its overall size, which cannot always satisfy the required design. 
         [0004]    In consideration of the situations, in recent years, attention has been given to a research and development of a spherical motor using a piezoelectric element. In particular, a piezoelectric motor for actuating a spherical member as a driven member by a frictional force using a piezoelectric unit has been expected as a spherical motor of a next generation having small-size and high accuracy. 
         [0005]    As a conventional example of a typical application of a motor of this type, there has been known a digital camera that is configured as described in JP-A-2000-059674. The digital camera is provided with an imaging unit, and the imaging unit has: a unit body; a first support frame for supporting the unit body swingably in a vertical direction; a second supporting member for supporting the unit body rotatably in a horizontal direction; an actuator for rotating the unit body in each of vertical and transverse directions; and a position detector for detecting a rotating position of the unit body. The unit body is formed in a shape of a capsule having both cylindrical ends covered with a semispherical surface, and there is provided an imaging unit having an imaging lens on a center of one of the semispherical surfaces and an imaging element in a rear position from the imaging lens. Furthermore, the actuator is disposed to protrude from an upper position of a short side of the second supporting member, and a tip of the actuator is provided to be in contact with a center of the semispherical surface on a rear side of the unit body. 
         [0006]    The actuator has a configuration in which a piezoelectric element such as PZT is placed on four side faces of an elastic member having a shape of a square pole, and furthermore, a lamination type piezoelectric element and an abutting piece are placed on an upper end face. The abutting piece is provided with a projection for abutting on the semispherical surface of the unit body. 
         [0007]    The imaging unit is set to a predetermined position in which the imaging lens is not exposed from an opening portion in a camera body in a state in which a main switch of the camera is OFF, and the opening portion is shielded with the unit body so that the protection of the imaging lens and the shading of the imaging element are performed. When the main switch is turned ON, the imaging lens of the imaging unit is exposed from the opening portion so that a direction of an optical axis thereof is automatically set to a predetermined position in a front direction and a photographing operation can be performed. Thus, the imaging unit is controlled to be placed in the shielding position of the opening portion and the exposing position of the imaging lens depending on a change in a state of the main switch. 
         [0008]    According to the configuration as described above, the actuator having the piezoelectric element has such a structure that the unit body is directly rotated and actuated in each of the vertical and transverse directions. Therefore, it is possible to eliminate the complexity of the conventional structure having the serial multistage stacking configuration of the single-degree-of-freedom motors, thereby expecting a small-sized and multi-degree-of-freedom actuator mechanism. 
         [0009]    A similar configuration is also disclosed in JP-A-3-166081. 
         [0010]    However, the gimbal mechanism generally has a shaft misalignment caused by a manufacturing process or an assembly process. In a driven member having a spherical shape, particularly, the processing of a rotating bearing portion is difficult to perform and there is a tendency that the shaft misalignment is apt to be generated. An actuating displacement of the piezoelectric element is very small and a frictional contact state of the driven member and the piezoelectric unit greatly varies by the influence of the shaft misalignment. As a result, the actuator characteristic of the piezoelectric motor becomes unstable in some cases. It is also possible to separately provide a mechanism for absorbing the shaft misalignment of the gimbal mechanism, however, Since the size of the whole device is increased, the mechanism would become unsuitable for an application of an actual product so that a design for reducing a size is hindered. 
       SUMMARY 
       [0011]    According to a first aspect of the invention, there is provided a piezoelectric motor including: a base; first and second piezoelectric elements that are provided symmetrically on the base to face with each other, the first and second piezoelectric elements being respectively applied with AC driving voltages having a first frequency to actuate in opposite directions; first and second displacement enlarging mechanisms that respectively enlarge actuating displacements of the first and second piezoelectric elements through first and second levers that rotate around first and second fulcrums fixed to the base; first and second leaf springs that are respectively coupled to action points of the first and second levers at one ends thereof; and an actuating portion that is coupled to the other ends of the first and second leaf springs and swings in accordance with actuation of the first and the second piezoelectric elements, the actuating portion being urged against a driven member to actuate the driven member with a frictional force between the actuating portion and the driven member. 
         [0012]    According to a second aspect of the invention, there is provided a camera device including: a camera module having a spherical driven portion and an imaging device provided in the spherical driven portion; and a piezoelectric motor that actuates the spherical driven portion to control the direction of the camera module, the piezoelectric motor including: a base; first and second piezoelectric elements that are provided symmetrically on the base to face with each other, the first and second piezoelectric elements being respectively applied with AC driving voltages having a first frequency to actuate in opposite directions; first and second displacement enlarging mechanisms that respectively enlarge actuating displacements of the first and second piezoelectric elements through first and second levers that rotate around first and second fulcrums fixed to the base; first and second leaf springs that are respectively coupled to action points of the first and second levers at one ends thereof; and an actuating portion that is coupled to the other ends of the first and second leaf springs and swings in accordance with actuation of the first and the second piezoelectric elements, the actuating portion being urged against the spherical driven member to actuate the spherical driven member with a frictional force between the actuating portion and the spherical driven member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    In the accompanying drawings: 
           [0014]      FIG. 1  is a perspective view showing a structure of a piezoelectric motor according to a first embodiment of the present invention; 
           [0015]      FIG. 2  is a view for explaining an operation of the piezoelectric motor in  FIG. 1 , illustrating a moving direction of each portion from a first state ( 1 ) to a fourth state ( 4 ); 
           [0016]      FIG. 3  is a graph showing a temporal variation in a driving voltage to be applied to a piezoelectric element of the piezoelectric motor shown in  FIG. 1 ; 
           [0017]      FIG. 4  is a perspective view showing a motion of a actuating portion of the piezoelectric motor shown in  FIG. 1 ; 
           [0018]      FIG. 5  is a perspective view showing a situation in which the piezoelectric motor shown in  FIG. 1  is used in an in-plane straight actuating operation of a planar driven member; 
           [0019]      FIG. 6  is a perspective view showing a situation in which the piezoelectric motor of  FIG. 1  is used in a rotating and actuating operation of a cylindrical driven member; 
           [0020]      FIG. 7A  is a front view showing an example of a positional relationship between a leaf spring mechanism and a actuator in the piezoelectric motor shown in  FIG. 1 , and  FIG. 7B  is an explanatory view showing a frequency of a force in each direction which is applied to a center of gravity of the actuator shown in  FIG. 7A ; 
           [0021]      FIG. 8A  is a front view showing a different example from  FIG. 7A , illustrating the positional relationship between the leaf spring mechanism and the actuator in the piezoelectric motor shown in  FIG. 1 , and  FIG. 8B  is an explanatory view showing a frequency of a force in each direction which is applied to the center of gravity of the actuator shown in  FIG. 8A ; 
           [0022]      FIG. 9A  is a front view showing a different example from  FIGS. 7A and 8A , illustrating the positional relationship between the leaf spring mechanism and the actuator in the piezoelectric motor shown in  FIG. 1 , and  FIG. 9B  is an explanatory view showing a frequency of a force in each direction which is applied to the center of gravity of the actuator shown in  FIG. 9A ; 
           [0023]      FIG. 10  is a perspective view showing a structure of a piezoelectric motor according to a second embodiment of the invention; 
           [0024]      FIG. 11  is a perspective view showing a situation in which the piezoelectric motor of  FIG. 10  is used in an in-plane actuating operation of a planar driven member; 
           [0025]      FIG. 12  is a perspective view showing a situation in which the piezoelectric motor shown in  FIG. 10  is used in a rotating and actuating operation of a spherical driven member; 
           [0026]      FIG. 13  is a perspective view showing a variant of the piezoelectric motor shown in  FIG. 10 ; 
           [0027]      FIG. 14  is a perspective view showing a structure of a piezoelectric motor according to a third embodiment of the invention; 
           [0028]      FIG. 15  is a perspective view showing a structure of a piezoelectric motor according to a fourth embodiment of the invention; 
           [0029]      FIG. 16  is a typical perspective view showing a camera device according to a fifth embodiment of the invention; 
           [0030]      FIG. 17  is a typical perspective view showing a camera device according to a sixth embodiment of the invention; 
           [0031]      FIG. 18  is a typical perspective view showing a camera device according to a seventh embodiment of the invention; 
           [0032]      FIG. 19  is a typical perspective view showing a camera device according to an eighth embodiment of the invention; and 
           [0033]      FIG. 20  is a functional block diagram showing a function of a control device for controlling the camera device shown in  FIG. 19 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0034]    Hereinafter, embodiments of the invention will be described with reference to the drawings. The same or similar components are described with the same reference numerals and repetitive description will be omitted. In the following description, upper, lower, left and right directions are assumed to be relatively defined, and do not need to be always coincident with a direction of a gravity. 
       First Embodiment 
       [0035]      FIG. 1  is a perspective view showing a structure of a piezoelectric motor according to a first embodiment.  FIGS. 2 to 4  are views for explaining an operation of the piezoelectric motor shown in  FIG. 1 .  FIG. 2  is a perspective view showing a moving direction of each portion from a first state ( 1 ) to a fourth state ( 4 ) in the piezoelectric motor shown in  FIG. 1 .  FIG. 3  is a graph showing a temporal variation in a driving voltage to be applied to a piezoelectric element of the piezoelectric motor shown in  FIG. 1 .  FIG. 4  is a perspective view showing a movement of an actuating portion of the piezoelectric motor shown in  FIG. 1 . 
         [0036]    Moreover,  FIG. 5  is a perspective view showing a situation in which the piezoelectric motor shown in  FIG. 1  is used in an in-plane straight actuating motion of a planar driven member, illustrating an example in which a direct advancing type piezoelectric motor is configured by a driven member having a plate-shaped driven surface supported by a bearing (not shown) so as to enable a direct actuating operation.  FIG. 6  is a perspective view showing a situation in which the piezoelectric motor shown in  FIG. 1  is used in a rotating and actuating operation of a cylindrical driven member, illustrating an example in which a rotating type piezoelectric motor is configured by using a driven member having a driven surface having a shape of a cylindrical surface which is supported rotatably around a rotating shaft through a bearing (not shown). 
         [0037]    In a piezoelectric motor  110 , a first piezoelectric element  112   a  and a second piezoelectric element  112   b  are provided symmetrically with respect to a piezoelectric fixing portion  111   a  of a base  111 . The first piezoelectric element  112   a  and the second piezoelectric element  112   b  have reverse operating directions to each other, and one of ends thereof is coupled to the base  111 . Moreover, the other ends of the piezoelectric elements  112   a  and  112   b  are coupled to constitute a power point  11 , and both ends of the base  111  are provided with a first displacement enlarging mechanism  113   a  and a second displacement enlarging mechanism  113   b  which have a fulcrum  12  based on the principles of a lever. 
         [0038]    The power point  11  and the fulcrum  12  have notch structures having arc shapes, for example, and desirably have such a support structure as to permit a minute rotating displacement with an actuating displacement of each of the piezoelectric elements  112   a  and  112   b . The displacement enlarging mechanisms  113   a  and  113   b  enlarge the actuating displacements of the piezoelectric elements  112   a  and  112   b  based on the principles of a lever and constitute an action point  13 . When a distance between the power point  11  and the fulcrum  12  is represented by L 1  and a distance between the action point  13  and the fulcrum  12  is represented by L 2 , a displacement enlarging ratio is determined by a ratio of the distances of L 2 /L 1  and is properly selected depending on the design of individual applied apparatuses. 
         [0039]    The piezoelectric motor  110  is provided with a first leaf spring mechanism  114   a  and a second leaf spring mechanism  114   b  which are obtained by coupling the action points  13  of the displacement enlarging mechanisms  113   a  and  113   b  to ends and coupling the other ends to a common actuating portion  115 . The actuating portion  115  serves to transmit a driving force to driven members  117  and  118  through a friction by a composite vibration generated via each of components of the displacement enlarging mechanisms  113   a  and  113   b  and the leaf spring mechanisms  114   a  and  114   b  based on the actuating displacements of the piezoelectric elements  112   a  and  112   b . The driven members  117  and  118  will be described below with reference to  FIGS. 5 and 6 . 
         [0040]      FIG. 2  shows an operation sequence of the piezoelectric motor  110 .  FIG. 3  shows driving voltage waveforms of the piezoelectric elements  112   a  and  112   b , illustrating driving voltages  116   a  and  116   b  of the piezoelectric elements  112   a  and  112   b . Moreover,  FIG. 4  shows a condition of an elliptic motion of the actuating portion  115 . Sine waves having different phases from each other by 90 degrees are set to be the driving voltages  116   a  and  116   b . In the case in which the driving voltage  116   b  is delayed in a phase of 90 degrees with respect to the driving voltage  116   a  as shown in  FIG. 3 , an elliptic motion shown in  FIG. 4  can be obtained. In other words, when the driving voltage is applied to the piezoelectric element  112   a  as a step ( 2 ) shown in  FIG. 3 , the actuating portion  115  is moved downward in a rightward direction in the drawing from a position in step ( 1 ) as shown in step ( 2 ) shown in  FIG. 2  depending on the actuating displacement on the action point  13  of the displacement enlarging mechanism  113   a . This is achieved by utilizing the bending deformation of the leaf spring mechanisms  114   a  and  114   b . Subsequently, the operation of step ( 2 )-&gt;step ( 3 )-&gt;step ( 4 )-&gt;step ( 1 )-&gt;step ( 2 ) in the drawing is repeated so that the elliptic motion is obtained in the same manner. 
         [0041]    According to the structure in which the driven member (not shown) is urged downward from above in  FIG. 4 , the elliptic motion is performed with the actuating portion  115  abutting on the driven member and a driving force is transmitted from the actuating portion  115  through a friction to the driven member by the motion so that the driven member is rotated or directly driven. 
         [0042]      FIG. 5  is a perspective view showing a situation in which the piezoelectric motor  110  in  FIG. 1  is used in the in-plane straight actuating operation of the driven member  117 . The driven member  117  has a plate-shaped driven surface  117   a  and is supported to be linearly movable in a planar direction of the driven surface  117   a . Although  FIG. 3  shows the case in which the driving voltage  116   b  is delayed by a phase of 90 degrees with respect to the driving voltage  116   a , it is possible to electrically and easily control direct driving directions X 1  and X 2  of the driven member  117  shown in  FIG. 5  by selectively switching the case in which the driving voltage  116   b  is advanced by a phase of 90 degrees with respect to the driving voltage  116   a.    
         [0043]      FIG. 6  is a perspective view showing a situation in which the driven member  118  is rotated and driven by using the piezoelectric motor  110  in  FIG. 1 . The driven member  118  has a driven surface  118   a  having a shape of a cylindrical surface and is supported rotatably around a rotating shaft  2 . In this case, a control in a rotating direction is performed so that rotating and driving directions θ 1  and θ 2  can be electrically controlled easily. A driving speed can be regulated based on voltage values (vibrating displacements) of the driving voltages  116   a  and  116   b . Moreover, it is also possible to make a difference between the voltage values (vibrating displacements) of the driving voltages  116   a  and  116   b  depending on a driving direction of the driven member  118 . 
         [0044]    Although the elliptic motion of the actuating portion  115  has been described with reference to  FIGS. 2 to 4 , the elliptic motion is not restricted but another well-known method, for example, an actuating method using a rapid deforming motion may be employed. In the case in which a larger moving amount than the actuating displacements of the displacement enlarging mechanisms  113   a  and  113   b  is to be applied to the driven members  117  and  118 , furthermore, the application is executed by a high speed feeding operation (a coarse motion) through a repetition of the elliptic motion or the rapid deforming motion. In the case in which fine positioning is to be performed within the actuating displacements of the displacement enlarging mechanisms  113   a  and  113   b , it is preferable to perform an ultrafine moving operation through a linear motion performed by using the expanding and contracting displacements of the piezoelectric elements  112   a  and  112   b  themselves. For a combinational driving principle of the piezoelectric element for performing a coarse and fine motion through the rapid deforming motion and the linear motion, it is possible to use a well-known method as those disclosed in JP-A-3-166081, for example. 
         [0045]      FIG. 7A  is a front view showing an example of a positional relationship between the leaf spring mechanism and the actuator in the piezoelectric motor shown in  FIG. 1 , and  FIG. 7B  is an explanatory view showing a frequency of a force in each direction which is applied to a center of gravity G 1  in the actuator shown in  FIG. 7A . A piezoelectric motor  210  shown in  FIG. 7A  is constituted in a relationship in which an angle α formed by the displacement enlarging mechanisms  113   a  and  113   b  and the leaf spring mechanisms  114   a  and  114   b  is approximately 45 degrees in the drawing and a positional relationship in which an intersection point on extended lines of the leaf spring mechanisms  114   a  and  114   b  and the center of gravity G 1  of the actuating portion  115  are almost coincident with each other. 
         [0046]    There is obtained a vibration characteristic in which a natural frequency f 1  in a vertical direction in the drawing of the actuating portion  115  in the piezoelectric motor  210  is almost coincident with a natural frequency f 2  in a transverse direction in the drawing, and a torsional natural frequency f 3  around the center of gravity G 1  of the actuating portion  115  is different from the natural frequencies f 1  and f 2 . By almost adapting the driving frequencies of the piezoelectric elements  112   a  and  112   b  to the natural frequencies f 1  and f 2 , it is possible to utilize a structural resonance, thereby enlarging the actuating displacement. In addition, it is possible to suppress a torsional vibration around the center of gravity G 1  of the actuating portion  115 . 
         [0047]      FIG. 8A  is a view showing a different example from that shown in  FIG. 7A , illustrating the positional relationship between the leaf spring mechanism and the actuator in the piezoelectric motor shown in  FIG. 1 .  FIG. 8A  is a front view showing the piezoelectric motor and  FIG. 8B  is an explanatory view showing a frequency of a force in each direction which is applied to a center of gravity G 2  of the actuator shown in  FIG. 8A . 
         [0048]    A piezoelectric motor  310  shown in  FIG. 8  is constituted in a relationship in which the angle α formed by the displacement enlarging mechanisms  113   a  and  113   b  and the leaf spring mechanisms  114   a  and  114   b  is smaller than 45 degrees and the intersection point on the extended line of the leaf spring mechanisms  114   a  and  114   b  is separated outward by a distance L 3  from the center of gravity G 2  of the actuating portion  115 . The center of gravity G 2  of the actuating portion  115  is provided apart from a actuating surface  115   a  of the actuating portion  115  by a distance L 4 , and a relationship of L 3 &lt;L 4  is desirable. There is obtained a vibration characteristic in which a natural frequency f 4  in the vertical direction in the drawing of the actuating portion  115  in the piezoelectric motor  310  is almost coincident with a torsional natural frequency f 6  around the center of gravity G 2  of the actuating portion  115  and a natural frequency f 5  in the transverse direction of the drawing is different from the natural frequencies f 4  and f 6 . By almost adapting the driving frequencies of the piezoelectric elements  112   a  and  112   b  to the natural frequencies f 4  and f 6 , a structural resonance can be utilized so that the actuating displacement is enlarged. 
         [0049]      FIG. 9A  is a view showing a different example from those shown in  FIGS. 7A and 8A , illustrating the positional relationship between the leaf spring mechanism and the actuator in the piezoelectric motor shown in  FIG. 1 .  FIG. 9A  is a front view showing the piezoelectric motor, and  FIG. 9B  is an explanatory view showing a frequency of a force in each direction which is applied to a center of gravity of the actuator shown in  FIG. 9A . 
         [0050]    A piezoelectric motor  410  shown in  FIG. 9A  is constituted in a relationship in which the angle α formed by the displacement enlarging mechanisms  113   a  and  113   b  and the leaf spring mechanisms  114   a  and  114   b  is smaller than 45 degrees and the intersection point on the extended line of the leaf spring mechanism  114   a  and  114   b  is separated inward by a distance L 5  from a center of gravity G 3  of the actuating portion  115 . The center of gravity G 3  of the actuating portion  115  is provided apart from the actuating surface  115   a  of the actuating portion  115  by a distance L 6 , and a relationship of L 5 &lt;L 6  is desirable. There is obtained a vibration characteristic in which a natural frequency f 7  in the vertical direction in the drawing of the actuating portion  115  in the piezoelectric motor  410  is almost coincident with a torsional natural frequency f 9  around the center of gravity G 3  of the actuating portion  115  and a natural frequency f 8  in the transverse direction of the drawing is different from the natural frequencies f 7  and f 9 . By almost adapting the driving frequencies of the piezoelectric elements  112   a  and  112   b  to the natural frequencies f 7  and f 9 , a structural resonance can be utilized so that the actuating displacement is enlarged. 
         [0051]    According to the first embodiment, the actuating displacement of the piezoelectric motor is enlarged. Consequently, it is possible to absorb the shaft misalignment of the driven member supported on the gimbal mechanism, thereby stabilizing the actuator characteristic to reduce the size of the whole device and to enhance a performance. 
       Second Embodiment 
       [0052]    Next, a piezoelectric motor according to a second embodiment of the invention will be described with reference to  FIGS. 10 to 12 . 
         [0053]      FIG. 10  is a perspective view showing a structure of the piezoelectric motor according to the second embodiment,  FIG. 11  is a perspective view showing a situation in which the piezoelectric motor shown in  FIG. 10  is used in an in-plane actuating operation of a planar driven member, and  FIG. 12  is a perspective view showing a situation in which the piezoelectric motor shown in  FIG. 10  is used for a rotating and actuating operation of a spherical driven member. 
         [0054]    As shown in  FIG. 10 , a piezoelectric motor  510  is a composite piezoelectric motor having a structure in which a common actuating portion  115  is provided and two pairs of piezoelectric units  110 A and  110 B are disposed orthogonally to each other. The piezoelectric units  110 A and  110 B have almost the same structures as the piezoelectric motor  110  according to the first embodiment, respectively. The actuating portion  115  and a base  111 C are common to the two pairs of piezoelectric units  110 A and  110 B respectively. The base  111 C is substantially cross-shaped in such a manner that four piezoelectric elements  112   a A,  112   a B,  112   b A and  112   b B and four displacement enlarging mechanisms  113   a A,  113   a B,  113   b A and  113   b B are fixed apart from one another by 90 degrees. 
         [0055]    By independently actuating the piezoelectric units  110 A and  110 B respectively, it is possible to operate the actuating portion  115  three-dimensionally, thereby performing an elliptic motion or a rapid deforming motion and a linear motion in an optional direction which is controlled. According to a structure in which a driven member (not shown) is urged downward from above in the drawing, the elliptic motion or the quick deforming motion and the linear motion are performed in a state in which the actuating portion  115  abuts on the driven member, and a driving force is transmitted from the actuating portion  115  through a friction to the driven member by the motion so that the driven member is rotated or directly driven. 
         [0056]      FIG. 11  is a perspective view showing a situation in which the piezoelectric motor  510  in  FIG. 10  is used in an in-plane actuating operation of a driven member  511 . As shown in  FIG. 11 , the driven member  511  has a plate-shaped driven surface  511   a . In the example shown in  FIG. 11 , a biaxial direct advancing type piezoelectric motor is constituted. By changing operations of the piezoelectric units  110 A and  110 B, direct driving directions X 3 , X 4 , X 5  and X 6  (not shown, a reverse direction to X 5 ) of the driven member  511  shown in  FIG. 11  can be electrically controlled easily. 
         [0057]      FIG. 12  is a perspective view showing a situation in which the piezoelectric motor  510  shown in  FIG. 10  is used in a rotating and actuating operation of a driven member  512 . The driven member  512  has a driven surface  512   a  having a spherical shape. In the example shown in  FIG. 12 , the piezoelectric motor  510  constitutes a biaxial rotating type piezoelectric motor. Also in this case, a control in a rotating direction is performed in the same manner as in  FIG. 11  and rotating and driving directions θ 3 , θ 4 , θ 5  and θ 6  (not shown) can be electrically controlled easily. 
         [0058]      FIG. 13  is a perspective view showing a piezoelectric motor  610  according to a variant of the piezoelectric motor in  FIG. 10 . The piezoelectric motor  610  constitutes a composite piezoelectric motor in which a common actuating portion  115  is provided and two piezoelectric units  110 A and  110 B are disposed orthogonally to each other. In leaf spring mechanisms  114   a A and  114   b A of the piezoelectric unit  110 A, a thickness of a leaf spring portion is set to be t 1  and a natural frequency constituting a vibrating system of the actuating portion  115  is set to be fA. In leaf spring mechanisms  114   a B and  114   b B of the piezoelectric motor  110 B, moreover, a thickness of a leaf spring portion is set to be t 2  and a natural frequency constituting the vibrating system of the actuating portion  115  is set to be fB. 
         [0059]    The natural frequencies fA and fB of the piezoelectric units  110 A and  110 B are set to be different from each other, and driving frequencies DfA and DfB of the piezoelectric units  110 A and  110 B are operated in the vicinity of the natural frequencies fA and fB, respectively. It is possible to easily regulate the natural frequencies fA and fB by varying the thicknesses t 1  and t 2  of the leaf spring portions. 
         [0060]    Consequently, it is possible to avoid a resonance obtained by combining the piezoelectric units  110 A and  110 B. Thus, it is possible to independently control the piezoelectric units  110 A and  110 B, thereby driving the actuating portion  115  in an optional direction. 
         [0061]    While the description has been given to the purport that the natural frequencies fA and fB are regulated by varying the thicknesses t 1  and t 2  of the leaf spring portions, this is not restricted but the regulation may be performed by changing widths of the leaf spring portions or using different materials. For a method of regulating the natural frequencies fA and fB, furthermore, an optimum method is properly selected depending on a design of an applied product. 
       Third Embodiment 
       [0062]    A piezoelectric motor according to a third embodiment of the invention will be described with reference to  FIG. 14 .  FIG. 14  is a perspective view showing a structure of the piezoelectric motor according to the third embodiment. The third embodiment is a variant of the first embodiment and a piezoelectric motor  710  is obtained by adding, to the piezoelectric motor  110  according to the first embodiment, coil springs  711   a  and  711   b  for urging displacement enlarging mechanisms  113   a  and  113   b  from an outside thereof. Forces F 2   a  and F 2   b  generated from the coil springs  711   a  and  711   b  have a relationship of F 1   a ≦F 2   a  and F 1   b ≦F 2   b  with respect to component forces F 1   a  and Fib in the displacement enlarging mechanisms  113   a  and  113   b  of a force F 1  for urging a actuating portion  115  downward from above in the drawing by a driven member (not shown). Moreover, parts for applying pressures to piezoelectric elements  112   a  and  112   b  may be added to the forces F 2   a  and F 2   b  generated in the coil springs  711   a  and  711   b.    
         [0063]    In general, a conventional piezoelectric motor has such a structure that a driven member and a piezoelectric element (corresponding to the piezoelectric elements  112   a  and  112   b  in the embodiment) and a pressure applying mechanism (corresponding to the coil springs  711   a  and  711   b  in the embodiment) are disposed in series. Therefore, there is still a problem in that a force to be applied to the piezoelectric element cannot be always optimized if a pressure to be applied to the driven member is optimized. 
         [0064]    According to the piezoelectric motor  710  in accordance with the embodiment, the piezoelectric elements  112   a  and  112   b  and the coil springs  711   a  and  711   b  are disposed in parallel with respect to the driven member. Therefore, it is possible to individually set the pressure to be applied to the driven member and the pressure to be applied to the piezoelectric element. Thus, the whole piezoelectric motor can be regulated optimally. 
       Fourth Embodiment 
       [0065]    A piezoelectric motor according to a fourth embodiment of the invention will be described with reference to  FIG. 15 .  FIG. 15  is a perspective view showing a structure of the piezoelectric motor according to the fourth embodiment. The fourth embodiment is obtained by combining the features of the second and third embodiments. In a piezoelectric motor  810  according to the embodiment, coil springs  811   a A,  811   b A,  811   a B and  811   b B for urging the displacement enlarging mechanisms  113   a A,  113   b A,  113   a B and  113   b B from an outside thereof are added to the piezoelectric motor  510  according to the second embodiment. 
         [0066]    Forces F 4   a , F 4   b , F 4   c  and F 4   d  generated in the coil springs  811   a A,  811   b A,  811   a B and  81  lbB have a relationship of F 3   a ≦F 4   a , F 3   b ≦F 4   b , F 3   c ≦F 4   c  and F 3   d ≦F 4   d  with respect to component forces F 3   a , F 3   b , F 3   c  and F 3   d  in the displacement enlarging mechanisms  113   a A,  113   b A,  113   a B and  113   b B of a force F 3  for urging a actuating portion  115  downward from above in the drawing by a driven member (not shown). Moreover, parts for applying pressures to piezoelectric elements  112   a A,  112   b A,  112   a B and  112   b B may be added to the forces F 4   a , F 4   b , F 4   c  and F 4   d  generated in the coil springs  811   a A,  811   b A,  811   a B and  811   b B. 
         [0067]    According to the piezoelectric motor  810  in accordance with the embodiment, in the same manner as in the piezoelectric motor  710  according to the third embodiment ( FIG. 14 ), the piezoelectric elements  112   a A,  112   b A,  112   a B and  112   b B and the coil springs  811   a A,  811   b A,  811   a B and  811   b B are disposed in parallel with respect to the driven member. Therefore, it is possible to individually set the pressure to be applied to the driven member and the pressure to be applied to the piezoelectric element. Thus, the whole piezoelectric motor can be regulated optimally. 
       Fifth Embodiment 
       [0068]    A camera device according to a fifth embodiment of the invention will be described with reference to  FIG. 16 .  FIG. 16  is a typical perspective view showing the camera device according to the fifth embodiment. 
         [0069]    In the camera device shown in  FIG. 16 , a camera module  901  is mounted on a spherical driven member  512 , and the driven member  512  can be rotated in an optional direction by means of a piezoelectric motor  510 . For the piezoelectric motor  510 , for example, the piezoelectric motor  510  described in the second embodiment is used. As described above, the piezoelectric motor  510  can directly drive the driven member  512  through two rotating shafts. Therefore, it is possible to regulate a direction of an elevation angle and that of an azimuth in the camera module  901 . 
         [0070]    An object  903  is captured by the camera module  901  and an object light beam P 1  reflected from the object  903  is led to the camera module  901  to form an image on an imaging plane  902  of the camera module  901 . In the case in which a direction of a visual line of the camera module  901  is to be switched from the object  903  to an object  904 , a processing is performed in accordance with a next procedure. 
         [0071]    When an operator inputs control information  905  about the object  904 , that is, control information  905  about the direction of an elevation angle and that of an azimuth in the camera module  901  and a direction of a rotating angle around a radial axis, visual line changing controller  906  generates an actuating signal for operating each piezoelectric element of the piezoelectric motor  510  based on the control information  905 . The actuating signal is input to actuator mechanism controller  907 , and the actuator mechanism controller  907  operates each piezoelectric element of the piezoelectric motor  510  to drive the driven member  512 . As a result, a direction of a visual line of the camera module  901  is switched into the object  904 , the object  904  is captured by the camera module  901 , an object light beam P 2  reflected from the object  904  is led to the camera module  901 , and an image is formed on the imaging plane  902  of the camera module  901 . 
         [0072]    According to the fifth embodiment, it is possible to implement a biaxial direct actuating operation of the camera module and a reduction in a weight of the driven member including the camera module at the same time, and to expect an implementation of an increase in a speed and an enhancement in accuracy. As a result, it is possible to enhance a control property in a visual line changing function of the camera device, and furthermore, to realize a reduction in a size of the camera device and to make the camera device compact. 
       Sixth Embodiment 
       [0073]    A camera device according to a sixth embodiment of the invention will be described with reference to  FIG. 17 .  FIG. 17  is a conceptual view showing a structure of the camera device according to the embodiment. 
         [0074]    In the camera device of  FIG. 17 , in the same manner as in the fifth embodiment, a camera module  911  is mounted on a spherical driven member  512 , and the driven member  512  can be rotated in an optional direction through a piezoelectric motor  510 . 
         [0075]    An object  913   a  is captured by the camera module  911  and an object light beam P 3  reflected from the object  913   a  is led to the camera module  911  to form an image on an imaging plane  912  of the camera module  911 . 
         [0076]    Furthermore, image tracking controller  914  is provided. The image tracking controller  914  generates an actuating signal for causing a direction of a visual line of the camera module  911  to follow the object  913   a  in a moving state M of the object  913   a  based on image information  916  which is captured, that is, an actuating signal for operating each piezoelectric element of the piezoelectric motor  510 . 
         [0077]    The actuating signal is input to actuator mechanism controller  915 , and the actuator mechanism controller  915  operates each piezoelectric element of the piezoelectric motor  510 , thereby driving the driven member  512 . As a result, the direction of the visual line of the camera module  911  photographs an object  913   b  after the movement of the object  913   a , leads an object light beam P 4  reflected from the object  913   b  to the camera module  911 , and forms an image on the imaging plane  912  of the camera module  911 . 
         [0078]    According to the sixth embodiment, it is possible to implement a biaxial direct actuating operation of the camera module and a reduction in a weight of the driven member including the camera module at the same time, and to expect an implementation of an increase in a speed and an enhancement in accuracy. As a result, it is possible to enhance a control property in an image tracking function of the camera device, and furthermore, to realize a reduction in a size of the camera device and to make the camera device compact. 
       Seventh Embodiment 
       [0079]    A camera device according to a seventh embodiment of the invention will be described with reference to  FIG. 18 .  FIG. 18  is a conceptual view showing a structure of the camera device according to the embodiment. 
         [0080]    In the camera device shown in  FIG. 18 , in the same manner as in the fifth and sixth embodiments, a camera module  921  is mounted on a spherical driven member  512 , and the driven member  512  can be rotated in an optional direction through a piezoelectric motor  510 . 
         [0081]    An object  923  is captured by the camera module  921  and an object light beam P 5  reflected from the object  923  is led to the camera module  921  to form an image on an imaging plane  922  of the camera module  921 . Furthermore, camera shaking correction controller  924  is provided. The camera shaking correction controller  924  prevents image shaking by obtaining an image shaking state Q of the object  923  based on image information  926  which is captured and driving the camera module  921  in vertical and horizontal directions, and generates an actuating signal for canceling the camera shaking, that is, an actuating signal for operating each piezoelectric element of the piezoelectric motor  510 . 
         [0082]    The actuating signal is input to actuator mechanism controller  925 , and the actuator mechanism controller  925  operates each piezoelectric element of the piezoelectric motor  510 , thereby driving the driven member  512 . As a result, the camera module  921  can obtain a clear image having less shaking. 
         [0083]    According to the seventh embodiment, it is possible to implement a biaxial direct actuating operation of the camera module and a reduction in a weight of the driven member including the camera module at the same time, and to expect an implementation of an increase in a speed and an enhancement in accuracy. As a result, it is possible to enhance a control property in a image stabilization function of the camera device, and furthermore, to realize a reduction in a size of the camera device and to make the camera device compact. 
         [0084]    Although the image shaking state Q is obtained by using the image information  926  and the actuating signal for canceling the camera shaking vibration is thus obtained in the description, it is also possible to employ a structure in which a sensor for measuring the camera shaking vibration is separately disposed in the camera device body to obtain the actuating signal for canceling the camera shaking vibration based on information of the sensor. In addition, it is also possible to employ such a structure as to obtain the actuating signal for canceling the camera shaking vibration based on both the image information  926  and the information of the sensor for measuring the camera shaking vibration. 
       Eighth Embodiment 
       [0085]    A camera device according to an eighth embodiment of the invention will be described with reference to  FIGS. 19 and 20 .  FIG. 19  is a conceptual view showing a structure of the camera device according to the embodiment. Moreover,  FIG. 20  is a functional block diagram showing a function of a control device for controlling the camera device in  FIG. 19 . 
         [0086]    In the camera device of  FIG. 19 , two camera modules  931   a  and  931   b  are mounted on separate driven members  512 , and the respective driven members  512  can be rotated in optional directions by separate piezoelectric motors  510  in the same manner as in the fifth to seventh embodiments. 
         [0087]    A common object  933  is captured by the two camera modules  931   a  and  931   b  which are provided in parallel, and an object light beam P 6  reflected from the object  933  is led to the camera module  931   a  to form an image on an imaging plane  932   a  of the camera module  931   a . Moreover, an object light beam P 7  reflected from the object  933  is led to the camera module  931   b  to form an image on an imaging plane  932   b  of the camera module  931   b.    
         [0088]    Furthermore, image processor  934  is provided and images α 1  and α 2  of the imaging planes  932   a  and  932   b  are input to the image processor  934 , thereby generating a three-dimensional image. In other words, the three-dimensional image is obtained by the images α 1  and α 2  in two directions having a parallax in a horizontal direction. Image correction controller  935  analyses the three-dimensional image obtained by the image processor  934  and determines an actuating signal for finely adjusting a shift in a vertical direction which is generated through a zooming operation or focusing of the camera modules  931   a  and  931   b  in addition to a fine adjustment for providing a proper three-dimensional image to an observer, that is, a fine adjustment in the horizontal direction. The actuating signal serves to operate each piezoelectric element of the piezoelectric motor  510 . 
         [0089]    The actuating signal is input to actuator mechanism controller  936 , and each piezoelectric element of the piezoelectric motor  510  is operated based on signals β 1  and β 2  output from the actuator mechanism controller  936  to drive the driven member  512 . A parallax adjustment and a shift correction in a vertical direction can be executed at a high speed with high accuracy so that an excellent three-dimensional image can be always provided. As compared with a conventional structure using a pan-tilt mechanism, moreover, it is possible to expect a more reduction in a size and a more compactness of the whole camera device. 
         [0090]    It is to be understood that the present invention is not limited to the specific embodiments described above and that the invention can be embodied with the components modified without departing from the spirit and scope of the invention. The invention can be embodied in various forms according to appropriate combinations of the components disclosed in the embodiments described above. For example, some components may be deleted from all components shown in the embodiments. Further, the components in different embodiments may be used appropriately in combination.