Abstract:
A piezoelectric actuator with low susceptibility to friction and rubbing is provided. A piezoelectric actuator of the present invention is provided with protruding portions, first piezoelectric actuators and second piezoelectric actuators. The protruding portions protrude from a first face of a base member toward a moving member, and are capable of supporting the moving member. The first piezoelectric actuators are provided along members other than the protruding portions and are capable of expanding and contracting in an orthogonal direction that is orthogonal to the first face. The second piezoelectric actuators are provided along the members other than the protruding portions and are capable of expanding and contracting in a direction other than the orthogonal direction.

Description:
[0001]    The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2009-114615 filed on May 11, 2009. The content of the application is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a piezoelectric actuator. 
         [0004]    2. Description of the Related Art 
         [0005]    A piezoelectric actuator causes electromechanical conversion elements to expand and contract with driving signals, and utilizing the expantion and contraction, the piezoelectric actuator generate progressive oscillation waves (hereinafter referred to “progressive wave”) at a driving surface of an elastic body. The piezoelectric actuator produces elliptical motions at the driving surface by the progressive waves, makes the relative movement member which pressingly contucts against wave peaks of the elliptical motions move to generate the driving force (see Japanese Patent Application Publication No. S58-148682) 
       SUMMARY OF THE INVENTION 
       [0006]    However, because the related art piezoelectric actuator utilizes elliptical motions, friction and rubbing occur at contact portions, and controlling the speed is complicated. 
         [0007]    An object of the present invention is to provide a piezoelectric actuator with low susceptibility to friction and rubbing, and a lens barrel and camera that employ the piezoelectric actuator. 
         [0008]    The present invention solves the above problem with the following solution. 
         [0009]    According to one aspect of the present invention, there is provided a piezoelectric actuator comprising: a protruding portion that protrudes from a first face of a base member toward a moving member and is capable of supporting the moving member; a first piezoelectric element that is disposed along a member other than the protruding portion and that is capable of expanding and contracting in an orthogonal direction that is orthogonal to the first face; and a second piezoelectric element that is disposed along the member other than the protruding portion and that is capable of expanding and contracting in a direction other than the orthogonal direction. 
         [0010]    The first piezoelectric element and the second piezoelectric element may be disposed so as not to touch one another. 
         [0011]    The first piezoelectric element may be disposed between the first face and a first member other than the protruding portion, and the second piezoelectric element may be disposed between the first member and a second member other than the first member. 
         [0012]    The first member may include a second face that is orthogonal to the first face, the second member may include a third face that is orthogonal to the first face, and the second piezoelectric element may be disposed between the second face and the third face. 
         [0013]    The moving member may be placed along a face of the second member at a side that is opposite from the side at which the first face is faced. 
         [0014]    The first piezoelectric element may be disposed between a first member other than the protruding portion and a second member other than the first member, and the second piezoelectric element may be disposed between the second member and the protruding portion. 
         [0015]    The protruding portion may include a second face that is orthogonal to the first face, the first member may include a third face that is orthogonal to the second face, and the second member may include a fourth face that is orthogonal to the first face and a fifth face that is orthogonal to the second face, the first piezoelectric element may be disposed between the third face and the fifth face, and the second piezoelectric element may be disposed between the second face and the fourth face. 
         [0016]    The moving member may be placed along a face of the first member at a side that is opposite from the side at which the first face is disposed. 
         [0017]    The piezoelectric actuator may further comprise a control section that performs control to expand and contract the first piezoelectric element and the second piezoelectric element, wherein the control section performs control to move the moving member in a direction of expansion and contraction of the second piezoelectric element by expanding the second piezoelectric element in a state in which the first piezoelectric element is expanded. 
         [0018]    In a state in which the first piezoelectric element and the second piezoelectric element are contracted, the moving member may be supported by the protruding portion. 
         [0019]    The protruding portion may include a third piezoelectric actuator that is capable of expanding and contracting in the orthogonal direction; and a fourth piezoelectric actuator that is capable of expanding and contracting in a direction other than the orthogonal direction. 
         [0020]    The third piezoelectric element and the fourth piezoelectric element may be disposed so as not to touch one another. 
         [0021]    The third piezoelectric element may be disposed between the first face and a third member other than the first member and the second member, and the fourth piezoelectric element is disposed between the third member and a fourth member other than the third member. 
         [0022]    The third member may include a fourth face that is orthogonal to the first face, the fourth member includes a fifth face that is orthogonal to the first face, and the fourth piezoelectric element is disposed between the fourth face and the fifth face. 
         [0023]    The moving member may be placed along a face of the fourth member at a side that is opposite from the side at which the first face is disposed. 
         [0024]    The control section may perform control to expand and contract the third piezoelectric element and the fourth piezoelectric element, and performs control to move the moving member in a direction of expansion and contraction of the fourth piezoelectric element by expanding the fourth piezoelectric element in a state in which the third piezoelectric element is expanded. 
         [0025]    The moving member may be supported by the second member when the first piezoelectric element is in the expanded state and the third piezoelectric element is in the contracted state, and is supported by the fourth member when the third piezoelectric element is in the expanded state and the first piezoelectric element is in the contracted state. 
         [0026]    According to another aspect of the present invention, there is provided a lens barrel provided with a piezoelectric actuator described above. 
         [0027]    According to further aspect of the present invention, there is provided a camera provided with a piezoelectric actuator described above. 
         [0028]    These constitutions may be suitably modified, and at least portions thereof may be substituted with other constituents. 
         [0029]    According to the present invention, a piezoelectric actuator with low susceptibility to occurrences of friction and rubbing may be provided. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]      FIG. 1  is a diagram schematically illustrating the structure of a piezoelectric actuator that is a first embodiment of the present invention; 
           [0031]      FIG. 2A  and  FIG. 2B  are timing charts describing operations of the piezoelectric actuator of the first embodiment.  FIG. 2A  shows an example of driving a moving member in a +X direction, and  FIG. 2B  shows an example of driving the moving member in the −X direction; 
           [0032]      FIG. 3A  to  FIG. 3D  are diagrams describing an operation of the piezoelectric actuator of the first embodiment step by step; 
           [0033]      FIG. 4  is a diagram schematically illustrating the structure of a piezoelectric actuator that is a second embodiment of the present invention; 
           [0034]      FIG. 5  is a diagram schematically illustrating the structure of a piezoelectric actuator that is a third embodiment of the present invention; 
           [0035]      FIG. 6  is a timing chart describing operation of the piezoelectric actuator of the third embodiment; 
           [0036]      FIG. 7A  to  FIG. 7D  are diagrams describing the operation of the piezoelectric actuator of the third embodiment step by step; 
           [0037]      FIG. 8  is a schematic perspective view of a piezoelectric motor that is a variant example of the present invention; 
           [0038]      FIG. 9  is a diagram illustrating the structure of a driving mechanism of a piezoelectric actuator of a variant example of the present invention; and 
           [0039]      FIG. 10  is a diagram illustrating the structure of a lens barrel and camera provided with an embodiment of the piezoelectric actuator. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment 
       [0040]    Herebelow, a first preferred embodiment of the present invention is described with reference to the attached drawings and suchlike. 
         [0041]      FIG. 1  is a diagram schematically illustrating the structure of a piezoelectric actuator  10  that is the first embodiment of the present invention. In the descriptions hereinafter, directions are indicated by X-Y coordinates as shown in the drawings. That is, the left-right direction in the drawings is the X axis direction, with the right side being the positive side and the left side being the negative side, and the vertical direction orthogonal to the X direction is the Y axis direction, with the upper side being the positive side and the lower side being the negative side. 
         [0042]    The piezoelectric actuator  10  is provided with a base member  11 , a moving member  12  that is movable relative to the base member  11 , driving mechanisms  20  that drive to move the moving member  12 , and a control device  30  that controls driving of the piezoelectric actuator  10 . In the present embodiment, the moving member  12  is described as moving linearly in the X direction relative to the base member  11 , but movements of the moving member  12  are not to be limited to straight lines and may be, for example, circular arcs (rotations). 
         [0043]    The base member  11  and the moving member  12  are formed as plates with respective predetermined thicknesses, and are disposed with plate faces thereof along the X direction. Holding bodies  13  are interposed between the base member  11  and the moving member  12 . The moving member  12  is pushingly urged by a predetermined force F toward the base member  11  (in the −Y direction) by unillustrated urging means. Thus, the base member  11  and the moving member  12  are disposed to be parallel with a spacing defined by the holding bodies  13 . The structure in the present embodiment is provided with the urging means, but this is not to be limiting. The moving member  12  may be urged toward the base member  11  (in the −Y direction) by gravity. 
         [0044]    The above-mentioned holding bodies  13 , which support the moving member  12 , are provided at the base member  11 , standing from an upper face thereof that opposes the moving member  12  (an opposing face  11 A). At the opposing face  11 A, a plural number of the driving mechanisms  20  are disposed with a predetermined spacing in the X direction. 
         [0045]    The holding bodies  13  are respectively disposed between the driving mechanisms  20  disposed with the predetermined spacing in the X direction. The shapes of the holding bodies  13  are rectangles with a predetermined height. Upper faces of the holding bodies  13  serve as flat support surfaces  13 A that correspond with a driven surface  12 A of the moving member  12 , which is described hereafter. Thus, the holding bodies  13  support the moving member  12  that is pushingly urged by the urging means with the support surfaces  13 A, and define the spacing between the base member  11  and the moving member  12 . Note that shapes and positions of arrangement of the holding bodies  13  are not to be limited by this constitution. 
         [0046]    As described above, the moving member  12  is disposed to be parallel with the base member  11  at the upper side (the +Y side) thereof, with the spacing defined by the holding bodies  13 . The face of the moving member  12  at the side that opposes the base member  11  (the lower face) is the driven surface  12 A, which is flat. 
         [0047]    As described above, the driving mechanisms  20  are plurally provided at the opposing face  11 A of the base member  11  with a predetermined spacing in the X direction. Each driving mechanism  20  is provided with a lifter  21  and a slider  22 . The driving mechanism  20  is further provided with a lift driving body  23 , which is interposed between the lifter  21  and the base member  11 , and a slide driving body  24 , which is interposed between the lifter  21  and the slider  22 . 
         [0048]    The lifter  21  is provided with a base plate portion  21 A and a support portion  213 . The base plate portion  21 A extends in the X direction. The support portion  21 B protrudes to a predetermined length upward (in the +Y direction) from an end portion of the base plate portion  21 A at the left side thereof in  FIG. 1 . Thus, a front face shape of the lifter  21  illustrated in  FIG. 1  is formed in a substantial L shape. 
         [0049]    The front face shape of the slider  22  illustrated in  FIG. 1  is formed in a substantial L shape that is inverted to match up with the lifter  21 . That is, a top plate portion  22 A extends in the X direction, and a support portion  22 B protrudes to a predetermined length downward (in the −Y direction) from an end portion of the top plate portion  22 A at the right side thereof in  FIG. 1 . A surface at the upper side of the top plate portion  22 A serves as a flat driving surface  22 C that corresponds with the driven surface  12 A of the moving member  12 . 
         [0050]    The lift driving body  23  and the slide driving body  24  are both piezoelectric elements with predetermined thicknesses that are constituted of a piezoelectric ceramic that exhibits the piezoelectric effect, or the like. The lift driving body  23  and the slide driving body  24  are each deformed by a predetermined amount in one direction (the thickness direction) by the application of a voltage. That is, the lift driving body  23  and the slide driving body  24  expand and contract in the predetermined directions by the voltages being turned on and off (expanding when the voltage is on and contracting when the voltage is off), and thus implement operation driving. Voltages are applied to the lift driving body  23  and the slide driving body  24  from respective driving circuits provided at the control device  30 . Thus, driving control is performed by the control device  30 . 
         [0051]    The lift driving body  23  is interposed between a bottom face  21 C of the lifter  21  and the upper face (the opposing face  11 A) of the base member  11 . The lift driving body  23  is provided with the direction of deformation (operation driving direction) thereof being the Y direction. Thus, the lift driving body  23  expands and contracts in the Y direction in accordance with control by the control device  30 , and the lifter  21  is operated to move with a predetermined stroke length in the Y direction relative to the base member  11 . 
         [0052]    The slide driving body  24  is interposed between a side face of the support portion  21 B of the lifter  21  at the right side thereof in  FIG. 1  (a connecting side face  21 D) and a side face of the support portion  22 B of the slider  22  at the left side thereof in  FIG. 1  (a connecting side face  22 D). The connecting side face  21 D of the lifter  21  and the connecting side face  22 D of the slider  22  are formed to be orthogonal to the opposing face  11 A of the base member  11 . The slide driving body  24  is provided with the direction of deformation (operation driving direction) thereof by the application of voltage being the X direction. Thus, the slide driving body  24  expands and contracts in the X direction in accordance with control by the control device  30 , and the slider  22  is operated to move with a predetermined stroke length in the X direction relative to the lifter  21 . 
         [0053]    As described above, in the driving mechanism  20 , the lifter  21  is operated to move with a predetermined stroke length in the Y direction relative to the base member  11  by driving of the lift driving body  23 , and the slider  22  is operated to move with a predetermined stroke length in the X direction relative to the lifter  21  by driving of the slide driving body  24 . 
         [0054]    The movement stroke length of the slider  22  in the Y direction relative to the base member  11 , by driving with the lift driving body  23 , is set as follows. As illustrated in  FIG. 1 , when the lift driving bodies  23  are in a non-operating state, the lifters  21  are disposed at the lower end of the movement stroke, and the upper faces of the sliders  22  (the driving surfaces  22 C) have a predetermined spacing (Δz) from the lower face of the moving member  12  (the driven surface  12 A), which is supported by the holding bodies  13 . When the lifters  21  are operated to rise by the driving of the lift driving bodies  23  and are disposed at the upper end of the movement stroke, the driving surfaces  22 C of the sliders  22  are a predetermined distance to the upper side relative to the driven surface  12 A of the moving member  12  as supported by the holding bodies  13 , as shown by the two-dot chain lines in  FIG. 1 . 
         [0055]    With this setting, in accordance with the driving of the lift driving bodies  23 , the driving mechanisms  20  (i.e., the lifters  21  via the sliders  22 ) lift up and support the moving member  12  that was supported by the holding bodies  13 . From this state, when the slide driving bodies  24  are driven and the sliders  22  are operated to move in the X direction relative to the lifters  21 , the moving member  12  being held by the sliders  22  moves in the X direction relative to the base member  11 . 
         [0056]    In the piezoelectric actuator  10  that is provided with the driving mechanism  20  constituted as described above, voltages applied to the lift driving bodies  23  and the slide driving bodies  24  of the driving mechanisms  20  are respectively controlled by the control device  30 , and drive to move the moving member  12  continuously. In the present embodiment, the plural driving mechanisms  20  provided at the base member  11  are all operated cyclically by the same control. 
         [0057]    Next, control by the control device  30  that continuously drives to move the moving member  12  is described with reference to  FIG. 2A  and  FIG. 2B  and  FIG. 3A  to  FIG. 3D  as well as  FIG. 1 .  FIG. 2A  and  FIG. 2B  are timing charts describing operations of the piezoelectric actuator  10 .  FIG. 2A  shows an example of driving the moving member in the +X direction, and  FIG. 2B  shows an example of driving the moving member in the −X direction.  FIG. 3A  to  FIG. 3D  are diagrams describing an operation of the piezoelectric actuator of the first embodiment step by step, which is an example in which the moving member  12  is driven in the +X direction. 
         [0058]    First, from the non-operating state shown in  FIG. 3A  (the same state as in  FIG. 1 ), the lift driving bodies  23  are driven (turned on). As a result, as shown in  FIG. 3B , the moving member  12  supported by the holding bodies  13  is supported by the driving mechanisms  20  (i.e., the sliders  22 ). After a predetermined duration (Δt 1 ) of the driving of the lift driving bodies  23 , the slide driving bodies  24  are driven (turned on). Therefore, as shown in  FIG. 3C , the sliders  22  are operated to move in the +X direction. As a result, the moving member  12  supported by the sliders  22  is moved in the +X direction by an amount corresponding to the movement stroke of the sliders  22  by the slide driving bodies  24 . 
         [0059]    Then, the driving of the lift driving bodies  23  is stopped (turned off). Therefore, as shown in  FIG. 3D , the support of the moving member  12  by the driving mechanisms  20  (the sliders  22 ) is removed, and the moving member  12  is supported by the holding bodies  13 . Then, a predetermined duration (Δt 2 ) after the driving of the lift driving bodies  23  has stopped (been turned off), the driving of the slide driving bodies  24  is stopped (turned off). Thus, the piezoelectric actuator  10  returns to the non-operating state shown in  FIG. 3A . When the sliders  22  are returning to the non-operating state, the sliders  22  are not supporting the moving member  12  and do not operate to move the moving member  12 . Hence, by rapidly repeating the steps described above, the moving member  12  may be driven to move smoothly in the +X direction. 
         [0060]    The above-described steps are an example in which the moving member  12  is driven in the +X direction. The moving member  12  may be driven in the −X direction by the driving mechanisms  20  being driven as in the timing chart shown in  FIG. 2B . That is, from the non-operating state shown in  FIG. 1 , the slide driving bodies  24  are driven (turned on) and, a predetermined duration (Δt 3 ) later, the lift driving bodies  23  are driven (turned on). As a result, the moving member  12  is supported by the driving mechanisms  20  (the sliders  22 ). 
         [0061]    Then, the driving of the slide driving bodies  24  is stopped (turned off). Therefore, the sliders  22  are operated to move in the −X direction, and the moving member  12  is moved in the −X direction by the amount corresponding to the movement stroke of the sliders  22  by the slide driving bodies  24 . 
         [0062]    A predetermined duration (Δt 4 ) after the driving of the slide driving bodies  24  has stopped (been turned off), the driving of the lift driving bodies  23  is stopped (turned off), and the holding of the moving member  12  by the driving mechanisms  20  (the sliders  22 ) is removed. Therefore, the moving member  12  is supported by the holding bodies  13  and the piezoelectric actuator  10  returns to the non-operating state shown in  FIG. 1 . 
         [0063]    By rapid repetition of the steps described above, the moving member  12  may be driven to move in the −X direction. 
         [0064]    According to the present embodiment, the following effects are provided. 
         [0065]    (1) In the structure of the present embodiment, the moving member  12  is supported by the driving of the lift driving bodies  23 , and the supported moving member  12  is operated to move by the driving of the slide driving bodies  24 . That is, the respective directions of action of the lift driving bodies  23  and the slide driving bodies  24  match directions in which the moving member  12  is operated, and the two actions are performed independently. Velocities (speeds and directions) of forces relating to the respective operations are constant and there are no unnecessary relative displacements (scraping) due to variations in speed between the driving mechanisms  20  (the sliders  22 ) and the moving member  12 . Therefore, abrasion caused by scraping may be suppressed. 
         [0066]    (2) The lift driving bodies  23  implement support of the moving member  12  and the slide driving bodies  24  implement movement operations of the moving member  12 . Because the lift driving body  23  and the slide driving body  24  do not touch one another, the effect of vibrations when one of the driving bodies is driven on the other driving body is extremely small. That is, support and movement driving of the moving member  12  are completely separate, and driving control thereof may be independent. Therefore, there is great freedom of control, and the piezoelectric actuator  10  may be constituted for high driving precision. 
       Second Embodiment 
       [0067]    Next, a second embodiment with a different structure from the above-described first embodiment is described.  FIG. 4  is a diagram schematically illustrating the structure of a piezoelectric actuator  100  of the second embodiment of the present invention. In  FIG. 4 , structural elements with the same functions as in the above-described first embodiment are assigned the same reference numerals, and descriptions thereof are not given. 
         [0068]    The piezoelectric actuator  100  differs from the piezoelectric actuator  10  of the above-described first embodiment (see  FIG. 1 ) in the structure of a driving mechanism  120 . That is, the driving mechanism  120  is provided with a lifter  121  and a slider  122 . The driving mechanism  120  is also provided with the lift driving body  23 , which drives the lifter  121 , and the slide driving body  24 , which drives the slider  122 . 
         [0069]    In the present second embodiment, the slider  122  is provided at the upper face of the base member  11  (the opposing face  11 A) to be movable in the X direction along the opposing face  11 A. The slider  122  is disposed adjacent to the holding body  13 , and is connected to the holding body  13  via the slide driving body  24 . That is, the slide driving body  24  is interposed between a connecting face  13 B formed at the holding body  13  and a connecting side face  122 A formed at the slider  122 . The connecting face  13 B of the holding body  13  and the connecting side face  122 A of the slider  122  are formed to be orthogonal to the opposing face  11 A of the base member  11 . 
         [0070]    The lifter  121  is provided at the upper face of the slider  122 , with the lift driving body  23  therebetween. That is, the lift driving body  23  is interposed between an upper face of the slider  122  (a connecting top face  122 B) and a bottom face of the lifter  121  (a connecting bottom face  121 A). The connecting top face  122 B of the slider  122  and the connecting bottom face  121 A of the lifter  121  are both formed to be parallel with the opposing face  11 A of the base member  11 . 
         [0071]    According to this constitution, the slider  122  and the lifter  121  (i.e., the driving mechanism  120 ) are operated to move in the X direction by the driving of the slide driving body  24 . Further, the lifter  121  is operated to move in the Y direction (operated to rise and fall) relative to the slider  122  by the driving of the lift driving body  23 . 
         [0072]    The movement stroke length of the lifter  121  in the Y direction by the driving of the lift driving body  23  is set as follows. As illustrated in  FIG. 4 , when the lift driving body  23  is in the non-operating state, the lifter  121  is disposed at the lower end of the movement stroke, and an upper face of the lifter  121  (a driving surface  121 B) has a predetermined spacing (Δz) from the lower face of the moving member  12  (the driven surface  12 A), which is supported by the holding bodies  13 . When the lifters  121  are operated to rise by the driving of the lift driving bodies  23  and are disposed at the upper end of the movement stroke, the driving surfaces  121 B are a predetermined distance to the upper side relative to the driven surface  12 A of the moving member  12  as supported by the holding bodies  13 , as shown by the two-dot chain lines in  FIG. 4 . 
         [0073]    With this setting, in accordance with the driving of the lift driving bodies  23 , the driving mechanisms  120  (i.e., the lifters  121 ) lift up and support the moving member  12  that was supported by the holding bodies  13 . From this state, when the slide driving bodies  24  are driven and the sliders  122  are operated to move in the X direction relative to the holding bodies  13 , the moving member  12  held by the sliders  122  moves in the X direction relative to the base member  11 . 
         [0074]    The piezoelectric actuator  100  that is provided with the driving mechanisms  120  structured as described above may continuously drive the moving member  12  to move in the X direction by controlling driving of the lift driving bodies  23  and the slide driving bodies  24 . This control may be the same as in the above-described first embodiment, and is not described. 
         [0075]    According to the present second embodiment, similarly to the above-described first embodiment, scraping and abrasion caused by scraping may be suppressed. Furthermore, because support and movement driving of the moving member  12  are completely separate and driving control thereof may be independent, there is great freedom of control, and the piezoelectric actuator  100  may be constituted for high driving precision. 
       Third Embodiment 
       [0076]    Next, a third embodiment is described.  FIG. 5  is a diagram schematically illustrating the structure of a piezoelectric actuator  200  of the third embodiment of the present invention. In  FIG. 5 , structural elements with the same functions as in the above-described first embodiment are assigned the same reference numerals, and descriptions thereof are not given. 
         [0077]    Similarly to the piezoelectric actuator  10  of the above-described first embodiment (see  FIG. 1 ), the piezoelectric actuator  200  illustrated in  FIG. 5  is provided with a plural number of the driving mechanisms  20 . In the present embodiment, however, the holding bodies  13  of the first embodiment (see  FIG. 1 ) are not provided. Instead, second driving mechanisms  220  are provided. 
         [0078]    That is, the driving mechanisms  20  and the second driving mechanisms  220  are disposed between the base member  11  and the moving member  12 . The driving mechanisms  20  and the second driving mechanisms  220  are provided alternately on the opposing face  11 A of the base member  11  with a predetermined spacing in the X direction. 
         [0079]    The driving mechanisms  20  have the same structure as the driving mechanisms  20  of the piezoelectric actuator  10  of the above-described first embodiment (see  FIG. 1 ), and descriptions thereof are not given. The second driving mechanisms  220  have the same structure as the driving mechanisms  20  but different reference numerals are assigned to the structural elements. 
         [0080]    That is, each second driving mechanism  220  is provided with a lifter  221 , a slider  222 , a lift driving body  223  and a slide driving body  224 . 
         [0081]    The lift driving body  223  is interposed between the bottom face of the lifter  221  (a connecting bottom face  221 C) and the top face of the base member  11  (the opposing face  11 A), and connects the base member  11  with the lifter  221 . The slide driving body  224  is interposed between a connecting side face  2210  of the lifter  221  and a connecting side face  222 D of the slider  222 , and connects the lifter  221  with the slider  222 . 
         [0082]    In the second driving mechanism  220 , the lifter  221  is operated to move with a predetermined stroke length in the Y direction relative to the base plate portion by driving of the lift driving body  223 , and the slider  222  is operated to move with a predetermined stroke length in the X direction relative to the lifter  221  by driving of the slide driving body  224 . The slider  222  rises and falls in association with movements of the lifter  221  in the Y direction (rises and falls) caused by the driving of the lift driving body  223 . The movement stroke length of the slider  222  in the Y direction relative to the base member  11  due to the driving of the lift driving body  223  is set equal to that of the driving mechanism  20 . 
         [0083]    Similarly to the driving mechanisms  20 , the second driving mechanisms  220  that are structured thus are controlled by the control device  30 . That is, in accordance with the driving of the lift driving bodies  223 , the lifters  221 , via the sliders  222 , lift up and support the moving member  12  that was supported by the holding bodies  13 . Then, in the state in which the moving member  12  is supported, when the slide driving bodies  224  are driven and the sliders  222  are operated to move in the X direction relative to the lifters  221 , the moving member  12  being held by the sliders  222  moves in the X direction relative to the base member  11 . 
         [0084]    As mentioned above, the driving mechanisms  20  and the second driving mechanisms  220  have the same structures, but timings of driving control thereof are different. The driving mechanisms  20  and the second driving mechanisms  220  mutually alternately implement holding and movement operation of the moving member  12  and release holding of the moving member  12 , and thus operate to move the moving member  12  in the X direction relative to the base member  11 . 
         [0085]    Next, driving control of the driving mechanisms  20  and the second driving mechanisms  220  for movement operation of the moving member  12  is described with reference to  FIG. 6  and  FIG. 7A  to  FIG. 7D  as well as the above-described  FIG. 5 .  FIG. 6  is a timing chart describing operation of the piezoelectric actuator  200 , and illustrates an example of driving the moving member  12  in the +X direction.  FIG. 7A  to  FIG. 7D  are diagrams describing the operation of the piezoelectric actuator  200  step by step, which is the example in which the moving member  12  is driven in the +X direction. 
         [0086]    Basic operations of the driving mechanisms  20  and the second driving mechanisms  220  are the same as in the above-described first embodiment. That is, the lift driving bodies  23  or  223  are driven (turned on) and support the moving member  12  with the sliders  22  or  222 . Then the slide driving bodies  24  or  224  are driven (turned on) and the moving member  12  held by the sliders  22  or  222  moves in the +X direction. Thereafter, the driving of the lift driving bodies  23  or  223  stops (is turned off) and the holding of the moving member  12  by the sliders  22  or  222  is released, and the driving of the slide driving bodies  24  or  224  stops (is turned off) and the piezoelectric actuator  200  returns to the state before driving. 
         [0087]    By offsetting driving control by a predetermined duration T between the driving mechanisms  20  and the second driving mechanisms  220 , it is possible to drive the moving member  12  while supporting the moving member  12 . 
         [0088]    Herebelow, control of the driving mechanisms  20  and the second driving mechanisms  220  is described in more detail. In the non-operating state shown in  FIG. 7A  (the same state as in  FIG. 5 ), the driving mechanisms  20  (the lift driving bodies  23  and the slide driving bodies  24 ) are in a driving state and the second driving mechanisms  220  (the lift driving bodies  223  and the slide driving bodies  224 ) are in a non-driving state. In this initial state, the driving mechanisms  20  are supporting the moving member  12 . 
         [0089]    From this initial state, the lift driving bodies  223  of the second driving mechanisms  220  are driven. Hence, as shown in  FIG. 7B , both the driving mechanisms  20  and the second driving mechanisms  220  support the moving member  12 . 
         [0090]    After a predetermined duration (Δt 5 ) of the driving of the lift driving bodies  223  of the second driving mechanisms  220 , the driving of the lift driving bodies  23  of the driving mechanisms  20  stops (is turned off) and the support of the moving member  12  by the driving mechanisms  20  is removed. Hence, as shown in  FIG. 7C , the piezoelectric actuator  200  is in a state in which only the second driving mechanisms  220  are supporting the moving member  12 . That is, the second driving mechanisms  220  have replaced the driving mechanisms  20  in supporting the moving member  12 . 
         [0091]    Then, a predetermined duration (Δt 6 ) after the driving of the lift driving bodies  23  of the driving mechanisms  20  has stopped, the slide driving bodies  224  of the second driving mechanisms  220  are driven (turned on). Thus, the moving member  12  supported by the second driving mechanisms  220  moves in the +X direction. At the same time, the driving of the lift driving bodies  23  of the driving mechanisms  20  stops (is turned off). Thus, the piezoelectric actuator  200  goes into the state shown in  FIG. 7D . 
         [0092]    In the state shown in  FIG. 7D , the second driving mechanisms  220  (the lift driving bodies  223  and the slide driving bodies  224 ) are in the driving state and are supporting the moving member  12 . Meanwhile, the driving mechanisms  20  (the lift driving bodies  23  and the slide driving bodies  24 ) are in the non-driving state. In other words, the state shown in  FIG. 7D  is a state in which the operational states of the driving mechanisms  20  and the second driving mechanisms  220  are exchanged from the state shown in  FIG. 7A . 
         [0093]    Thereafter, control is performed to carry out the above-described steps with references to the driving mechanisms  20  and the second driving mechanisms  220  being switched. That is, the moving member  12  is supported by the driving mechanisms  20 , the support of the moving member  12  by the second driving mechanisms  220  is removed, and the moving member  12  is driven to move by the driving mechanisms  20 . The above-described process is repeated, and thus the moving member  12  may be driven to move smoothly in the +X direction. 
         [0094]    That is, as is illustrated in  FIG. 6 , the moving member  12  may be driven to move in the +X direction by the second driving mechanisms  220  performing exactly the same operations as the operations of the driving mechanisms  20 , offset by the predetermined duration T. It is sufficient if the time differential (T) between the driving mechanisms  20  and the second driving mechanisms  220  is at least a duration from the moving member  12  being supported to the feeding driving ending. 
         [0095]    In the present embodiment too, similarly to the above-described first embodiment, the moving member  12  may be driven to move in the −X direction. In this case, it is sufficient to reverse the control for turning on and off the lift driving bodies  23  of the driving mechanisms  20  and the lift driving bodies  223  of the second driving mechanisms  220  in each of the above-described steps, detailed descriptions are not given. 
         [0096]    In the above descriptions, the third embodiment is described as being provided with the second driving mechanisms  220  with the same structure as the driving mechanisms  20  instead of the holding bodies  13  of the above-described first embodiment, and as implementing different control for the driving mechanisms  20  and the second driving mechanisms  220 . However, taking a different point of view, the third embodiment may be described as having a plural number of the driving mechanism  20  arranged with the predetermined spacing in the X direction and alternatingly grouped, with the moving member  12  being controlled to move in the X direction relative to the base member  11  by different control being implemented for the groups. 
         [0097]    According to the above-described third embodiment, the following effects are provided. Specifically, similarly to the above-described first embodiment, scraping and abrasion caused by scraping may be suppressed. Furthermore, because support and movement driving of the moving member  12  are completely separate and driving control thereof may be independent, there is great freedom of control, and the piezoelectric actuator  200  may be constituted for high driving precision. 
         [0098]    In addition, because the moving member  12  is supported and operated to move at the same height (a Y direction position) by the driving mechanisms  20  and the second driving mechanisms  220 , the moving member  12  does not move in the vertical direction (the Y direction). Therefore, smooth operation is possible. 
         [0099]    The embodiments described above are not limiting, numerous modifications and alterations are possible and are to fall within the scope of equivalents of the present invention. 
         [0100]    (1) The above embodiments are structural examples in which the driving mechanisms  20  (and the second driving mechanisms  220 ) are linearly arranged, and thus the moving member  12  is operated to move linearly. However, the movement direction of the moving member  12  is not to be limited to a straight line, and may be circular. That is, a structure that performs rotation operations, by the driving mechanisms  20  being arranged in a circular ring, is possible.  FIG. 8  shows a schematic perspective view of a piezoelectric motor  300  that is an example thereof. 
         [0101]    The piezoelectric motor  300  illustrated in  FIG. 8  is provided with annularly arranged driving mechanisms  320  between a stator  301  corresponding to the base member  11  of the third embodiment (see  FIG. 5 ) and a rotor  302  corresponding to the moving member  12  (see  FIG. 5 ). 
         [0102]    The stator  301  is formed in an annular shape, a central portion of which is a circular aperture portion. The rotor  302  is formed substantially in a circular disc shape. A rotating shaft  303  is fixed to the rotor  302 . The rotating shaft  303  passes through the aperture portion at the central portion of the stator  301 , and is supported to be both movable by a predetermined amount in the axial direction and rotatable. The rotor  302  is pushingly urged to move closer to the stator  301  by unillustrated urging means. Thus, the stator  301  and the rotor  302  are made relatively rotatable with a predetermined spacing. 
         [0103]    The rotating shaft  303  protrudes from the stator  301  to the lower side in  FIG. 8 , and the protruding portion thereof outputs rotary force. In  FIG. 8 , an output gear  304  is attached to the rotating shaft  303 . 
         [0104]    The annularly arranged driving mechanisms  320  are constituted with structures the same as the driving mechanisms  20  and  220  of the third embodiment (see  FIG. 5 ) and plurally disposed in a circular ring arrangement. Each of the annularly arranged driving mechanisms  320  is provided with a lifter disc  321  and a slider disc  322  that is disposed to oppose the lifter disc  321 . 
         [0105]    The lifter discs  321  are attached to the stator  301  via lift driving bodies  323 . Lifters  321 A protrude from the upper faces of the lifter discs  321 , with a predetermined spacing in the circumferential direction. 
         [0106]    A plural number of sliders  322 A protrude from faces of the slider discs  322  that oppose the lifter discs  321  (i.e., lower faces), with a predetermined spacing. Positions of arrangement of the sliders  322 A correspond with locations of the spaces between the lifters  321 A provided at the lifter discs  321 . Between one circumferential direction side face of each slider  322 A and the lifter  321 A of the lifter disc  321 , a slide driving body  324  is interposed. Thus, the lifter disc  321  and the slider disc  322  are connected via the slide driving body  324  to be relatively non-movable in the vertical direction. A predetermined spacing is provided between the slider disc  322  and the rotor  302  disposed thereabove at non-driving times. 
         [0107]    In the piezoelectric motor  300  constituted as described above, the lifter discs  321  and the slider discs  322  are moved in the axial direction relative to the stator  301  by driving of the lift driving bodies  323 , and the slider discs  322  abut against the rotor  302 . In this state, the rotor  302  may be driven to turn about the rotating shaft  303  by driving of the slide driving bodies  324 . Control of the lift driving bodies  323  and the slide driving bodies  324  is the same as in the above third embodiment. 
         [0108]    In this structural example, the structures of the third embodiment are applied to the annularly arranged driving mechanisms  320 , but clearly the structures of the first embodiment may also be applied. 
         [0109]    (2) The numbers of the driving mechanisms  20  (and the second driving mechanisms  220 ) in the above embodiments are not to be limited to the numbers shown in the drawings. Obviously, greater numbers may be provided. The moving member  12  may be moved more smoothly by providing a larger number of the driving mechanisms  20  (and the second driving mechanisms  220 ). Furthermore, arrangements of the driving mechanisms  20  (and the second driving mechanisms  220 ) are not just to be single straight rows. They may be disposed in parallel rows. 
         [0110]    (3) In the above embodiments, the driving mechanisms  20  (and the second driving mechanisms  220 ) are constituted to drive the moving member  12  by the lift driving bodies  23  and  223  and the slide driving bodies  24  and  224  being displaced in their thickness directions (that is, by being displaced in the Y direction in  FIG. 1  and  FIG. 5 ). However, the constitution illustrated in  FIG. 9  is also possible.  FIG. 9  is a diagram illustrating the structure of a driving mechanism  420  according to a variant example. 
         [0111]    In  FIG. 9 , a slider  421  is a member the same as the lifter  21  in  FIG. 1  (or the lifter  221  in  FIG. 5 ), and a lifter  422  is a member the same as the slider  22  in  FIG. 1  (or the slider  222  in  FIG. 5 ). A slide driving body  423  is disposed at the same position as the lift driving body  23  in  FIG. 1  (or the lift driving body  223  in  FIG. 5 ), and a lift driving body  424  is disposed at the same position as the slide driving body  24  in  FIG. 1  (or the slide driving body  224  in  FIG. 5 ), 
         [0112]    The slide driving body  423  and the lift driving body  424  are both piezoelectric elements with predetermined thicknesses that are constituted of a piezoelectric ceramic that exhibits the piezoelectric effect, or the like. The slide driving body  423  is deformed, by the application of a voltage, by a predetermined amount in a direction orthogonal to the thickness direction thereof (i.e., the X direction in  FIG. 9 ). That is, the slide driving body  423  expands and contracts in the X direction by the voltage being turned on and off. Consequently, the slider  421  may be moved in the X direction. The lift driving body  424  is also deformed, by the application of a voltage, by a predetermined amount in a direction orthogonal to the thickness direction thereof (i.e., the Y direction in  FIG. 9 ). That is, the lift driving body  424  expands and contracts in the Y direction by the voltage being turned on and off. Consequently, the lifter  422  may be moved in the Y direction. 
         [0113]    The moving member  12  may be controlled to drive in the same manner as in  FIG. 1  or  FIG. 5  by the slide driving bodies and lift driving bodies of  FIG. 9  being controlled in a similar manner to the slide driving bodies and lift driving bodies of  FIG. 1  or  FIG. 5 . 
         [0114]    (4)  FIG. 10  is a structural diagram of a camera  101  which is provided with the piezoelectric motor  300  that is constituted by arranging the driving mechanisms  20  (or  120 ,  220  or  420 ) in an annular arrangement as in  FIG. 9 . In  FIG. 10 , the camera  101  is provided with a camera body  102  including an imaging device  108  and a lens barrel  103  including a lens  107 . The lens barrel  103  is an interchangeable lens which is detachable from the camera body  102 . Although an example is illustrated in  FIG. 10  in which the lens barrel  103  is an interchangeable lens, this is not to be limiting. For example, it may be a lens barrel of a type that is integral with the camera body. 
         [0115]    The lens barrel  103  is provided with the lens  107 , a cam tube  106 , the gear  304 , the piezoelectric motor  300  and so forth. The piezoelectric motor  300  is used as a drive source that drives the  107  during focusing operations of the camera  101 . Driving force provided from the piezoelectric motor  300  is transmitted to the cam tube  106  via the gear  304 . The lens  107  is retained in the cam tube  106 . The lens  107  is a focusing lens that is moved substantially parallel to an optical axis direction L by the driving force of the piezoelectric motor  300  to adjust the focus. 
         [0116]    In  FIG. 10 , an image of an object is focused at an imaging plane of the imaging device  108  by a lens unit ncluding the lens  107 ) provided inside the lens barrel  103 . 
         [0117]    The focused object image is converted to electronic signals by the imaging device  108 , and these signals are A/D-converted. Thus, image data is obtained. 
         [0118]    The embodiments and variant examples may be suitably combined and used, but detailed descriptions are not given herein. Further, the present invention is not to be limited by the embodiments described hereabove.