Abstract:
A vibration actuator unit comprises: an electromechanical converting element that converts an electric vibration of an applied actuating voltage into a mechanical vibration; and a contact portion that contacts an actuated surface of an actuating subject and a transmits a mechanical vibration of the electromechanical converting element to the actuated surface as an actuating force, wherein the electromechanical converting element periodically bends within a first vibration plane crossing the actuated surface to vibrate the contact portion within the first vibration plane, and periodically bends within a second vibration plane crossing the first vibration plane to vibrate the contact portion within the second vibration plane.

Description:
[0001]    The contents of the following Japanese patent application(s) are incorporated herein by reference: 
         [0002]    2012-136989 filed in JP on Jun. 18, 2012; 
         [0003]    2012-161999 filed in JP on Jul. 20, 2012; and 
         [0004]    PCT/JP2013/003470 filed on May 31, 2013 
       BACKGROUND 
       [0005]    1. Technical Field 
         [0006]    The present invention relates to a vibration actuator unit, a stage apparatus, and an optical apparatus. 
         [0007]    2. Related Art 
         [0008]    There is a stage apparatus which moves a stage two-dimensionally (for example, refer to Patent Literature 1). Furthermore, there is an actuating apparatus provided with a scale and an encoder for detecting a displacement signal to control an actuating signal based on the displacement signal (for example, refer to Patent Literature 2). 
         [0009]    Patent Literature 1: Japanese Patent Application Publication No. H11-316607 Patent Literature 2: Japanese Patent Application Publication No. 2011-147266 
       SUMMARY 
       [0010]    As provided with actuators for actuating in a X direction and actuating in a Y direction respectively, the apparatus is large in scale. Addition of a scale and an encoder further increases a cost and a space factor. 
         [0011]    A first aspect of the present invention provides a vibration actuator unit comprising: an electromechanical converting element that converts an electric vibration of an applied actuating voltage into a mechanical vibration; and a contact portion that contacts an actuated surface of an actuating subject and a transmits a mechanical vibration of the electromechanical converting element to the actuated surface as an actuating force, wherein the electromechanical converting element periodically bends within a first vibration plane crossing the actuated surface to vibrate the contact portion within the first vibration plane, and periodically bends within a second vibration plane crossing the first vibration plane to vibrate the contact portion within the second vibration plane. 
         [0012]    A second aspect of the present invention provided an optical apparatus comprising the aforementioned vibration actuator unit. Furthermore, a third aspect of the present invention provides a stage apparatus comprising the aforementioned vibration actuator unit. 
         [0013]    A fourth aspect of the present invention provides a vibration actuator unit comprising: an electromechanical converting element that converts an applied actuating power into a mechanical vibration; a contacting portion that actuates an actuating subject article when a mechanical vibration is transmitted from the electromechanical converting element; a biasing force generating portion that generates a biasing force biasing the contacting portion toward the actuating subject article; and a position detecting portion that detects, based on a change in a physical amount to be a biasing force generated by the biasing force generating portion, a relative position between the actuating subject article and the electromechanical converting element. 
         [0014]    A fifth aspect of the present invention provides an optical apparatus comprising the aforementioned vibration actuator unit. Furthermore, the sixth aspect of the present invention provides a stage apparatus comprising the aforementioned vibration actuator unit. 
         [0015]    The summary clause does not necessarily describe all necessary features of the embodiments of the present invention. The present invention may also be a sub-combination of the features described above. The above and other features and advantages of the present invention will become more apparent from the following description of the embodiments taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a schematic cross sectional view of a stage apparatus  101 . 
           [0017]      FIG. 2  is a schematic exploded perspective view of the vibration actuator unit  201 . 
           [0018]      FIG. 3  is a schematic side view of vibration actuator unit  201 . 
           [0019]      FIG. 4  is a diagram illustrating wave patterns of actuating signals of the vibration actuator unit  201 . 
           [0020]      FIG. 5  is a schematic side view of the vibration actuator unit  201 . 
           [0021]      FIG. 6  is a schematic view showing a structure of the vibration actuator unit  201 . 
           [0022]      FIG. 7  is a diagram illustrating wave patterns of actuating signals of the vibration actuator unit  201 . 
           [0023]      FIG. 8  is a schematic side view of the vibration actuator unit  201 . 
           [0024]      FIG. 9  is a schematic cross sectional view of a stage apparatus  102 . 
           [0025]      FIG. 10  is a schematic exploded perspective view of the vibration actuator unit  202 . 
           [0026]      FIG. 11  is a diagram illustrating wave patterns of actuating signals of the vibration actuator unit  202 . 
           [0027]      FIG. 12  is a diagram illustrating wave patterns of actuating signals of the vibration actuator unit  202 . 
           [0028]      FIG. 13  is a schematic cross sectional view of a stage apparatus  103 . 
           [0029]      FIG. 14  is a schematic exploded perspective view of the vibration actuator unit  203 . 
           [0030]      FIG. 15  is a diagram illustrating a phase relation of the actuating signals. 
           [0031]      FIG. 16  is a schematic cross sectional view of an optical apparatus  104 . 
           [0032]      FIG. 17  is a schematic view of the optical apparatus  104 . 
           [0033]      FIG. 18  is a schematic view of an optical apparatus  105 . 
           [0034]      FIG. 19  is a schematic view of an optical apparatus  105 . 
           [0035]      FIG. 20  is a schematic view of an active rotating articulation apparatus  106 . 
           [0036]      FIG. 21  is a schematic cross sectional view of a camera system  500 . 
           [0037]      FIG. 22  is a cross sectional view of a lens unit  600 . 
           [0038]      FIG. 23  is a schematic cross sectional view of a vibration actuator unit  400 . 
           [0039]      FIG. 24  is a schematic view of an electromechanical converting element  420 . 
           [0040]      FIG. 25  is a wave pattern diagram of actuating signals. 
           [0041]      FIG. 26  is a schematic view illustrating an operation of an electromechanical converting element  420 . 
           [0042]      FIG. 27  is a cross sectional view of a lens unit  601 . 
           [0043]      FIG. 28  is a schematic plan view of a stage apparatus  450 . 
           [0044]      FIG. 29  is a schematic cross sectional view of a stage apparatus  451 . 
           [0045]      FIG. 30  is a schematic cross sectional view of the stage apparatus  451 . 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0046]    Hereinafter, some embodiments of the present invention will be described. The embodiments do not limit the invention according to the claims, and all the combinations of the features described in the embodiments are not necessarily essential to means provided by aspects of the invention. 
         [0047]      FIG. 1  is a schematic cross sectional view of a stage apparatus  101 . The stage apparatus  101  comprises a base  110 , biasing portions  120 , a moving stage  130  and a vibration actuator unit  201 . 
         [0048]    In the stage apparatus  101 , the biasing portions  120  and the vibration actuator unit  201  are provided on a flat upper surface of the base  110 . The vibration actuator unit  201  is fixed to the upper surface of the base  110  with a fixing portion  112 . The moving stage  130  is supported by the vibration actuator unit  201  from a downward side. 
         [0049]    The biasing portions  120  have a strut  122 , an elastic member  124 , a spherical seat  126  and a rotation ball  128 . The strut  122  extends from the upper surface of the base  110  upwardly in the figure, and also extends laterally to overhang the moving stage  130  in the figure. Between a distal end of the strut  122  and an upper surface of the moving stage  130 , the elastic member  124 , the spherical seat  126  and the rotation ball  128  are stacked. 
         [0050]    The rotation ball  128  contacts the upper surface of the moving stage  130 . The spherical seat  126  prevents the rotation ball  128  from displacement on an outer surface of the moving stage  130 , while it allows for rotation of the rotation ball  128 . The elastic member  124  is sandwiched between the strut  122  and the spherical seat  126  in a compressed state. Thereby, the spherical seat  126  and the rotation ball  128  are pressed downwardly from an upper end of the strut  122 . 
         [0051]    The aforementioned biasing portions  120  is provided at a plurality of positions on the moving stage  130  and cooperatively biases the moving stage  130  downwardly, in other words, in a direction approaching the base  110 . As the moving stage  130  is supported by the vibration actuator unit  201  from a downward side, a contact portion  210  provided at the upper end of the vibration actuator unit  201  is pressed against a lower surface of the moving stage  130 . 
         [0052]    Note that a structure of the biasing portions  120  is not limited to the example illustrated in the figure. As the biasing portions  120  is provided in order to maintain the contact portion  210  of the vibration actuator unit  201  and an actuated surface of the moving stage  130 , which is an actuating subject, to contact each other, the biasing portions  120  may be provided which generates a biasing force by other means such as a magnetic force, a gravity and a pressure of a working fluid. 
         [0053]      FIG. 2  is a schematic exploded perspective view of the vibration actuator unit  201 . The vibration actuator unit  201  has the contact portion  210 , a piezoelectric element  220 , a common electrode  235  and a plurality of individual electrodes  231 ,  232 ,  233 ,  234 . 
         [0054]    The contact portion  210  is fixed to an upper surface of the piezoelectric element  220  in the figure, and protrudes from an outer surface of the piezoelectric element  220  to contact the lower surface of the moving stage  130  in the figure. When the piezoelectric element  220  generates a mechanical vibration, the contact portion  210  is vibrated with the piezoelectric element  220 . 
         [0055]    The piezoelectric element  220  is formed from a piezoelectric material such as PZT. The piezoelectric material extends and contracts in a preliminarily polarized direction when a voltage is applied. In the example illustrated in the figure, a polarization is performed such that a direction indicated by an arrow Z in the figure is a polarization axis direction. Accordingly, when an actuating voltage is applied of which a voltage value periodically changes, the piezoelectric element  220  generates a mechanical vibration to extend and contract in the direction indicated by the arrow Z in the figure. 
         [0056]    The individual electrodes  231 ,  232 ,  233 ,  234  and the common electrode are formed from a conductive material such as a metal, and are mutually insulated. The common electrode  235  has approximately the same area as an adjacent piezoelectric element  220 , and is coupled to a reference potential, for example, to a ground potential. In other words, the piezoelectric element  220  is, as a whole, divided by the common electrode  235  into two blocks. 
         [0057]    The individual electrodes  231 ,  232 ,  233 ,  234  are respectively provided at positions opposing the common electrode  235  across the piezoelectric element  220 . Thereby, in the piezoelectric element  220 , a plurality of piezoelectric material blocks  221 ,  222 ,  223 ,  224  are formed which are sandwiched between any one of the individual electrodes  231 ,  232 ,  233 ,  234  and the common electrode  235 . In other words, the individual electrodes  231 ,  232 ,  233 ,  234  are provided along an arrangement direction of the piezoelectric material blocks  221 ,  222 ,  223 ,  224 . 
         [0058]    Accordingly, for example, when a voltage is applied to one individual electrode  231 , an electric field strongly acts on the piezoelectric material block  221  corresponding to the individual electrode  231 , such that the piezoelectric material block  221  extends or contracts. Likewise, when a voltage is applied to any one of the other individual electrodes  232 ,  233 ,  234 , the corresponding piezoelectric material blocks  222 ,  223 ,  224  extend or contract. In this manner, with the piezoelectric element  220  and the individual electrodes  231 ,  232 ,  233 ,  234 , an electromechanical converting element is formed which converts an electric vibration of an applied actuating voltage into a mechanical vibration. 
         [0059]    Note that, in the vibration actuator unit  201  in use, the contact portion  210 , the piezoelectric element  220 , the individual electrodes  231 ,  232 ,  233 ,  234  and the common electrode  235  in the figure are in a tight contact mutually. Such vibration actuator unit  201  is not necessarily produced of a combination of assemblies having the shape illustrated in the figure. For example, by layering piezoelectric materials and conductivity materials each of which has a layered shape one after another, the same structure as the vibration actuator unit  201  in the figure can be formed. 
         [0060]    Furthermore, in the example illustrated in the figure, the individual electrodes  231 ,  232 ,  233 ,  234  and the common electrode  235  are provided respectively on planes parallel to an arrow Y in the figure. However, each electrode can be provided at the other planes or corner portions of the piezoelectric element  220 . Furthermore, if the piezoelectric element  220  is formed in a tubular shape, the electrodes can also be provided on its inner surface. 
         [0061]      FIG. 3  is a schematic side view of the vibration actuator unit  201 .  FIG. 3  shows the vibration actuator unit  201  seen from the direction indicated by the arrow X in  FIG. 1  and  FIG. 2 , i.e., a direction normal to a portion of the individual electrodes  231 ,  232 . The same reference numerals are applied to elements in common with  FIG. 2  and overlapping descriptions are omitted. 
         [0062]    The individual electrodes  231 ,  232  are provided on right and left areas of the piezoelectric element  220  in the figure, respectively. Here, it is assumed that a B-phase actuating signal applied to the individual electrode  232  positioned on the left side in the figure, and a C-phase actuating signal applied to the individual electrode  233  positioned on a back side of the individual electrode  232  relative to the piezoelectric element  220 , periodically change a voltage at the same phase. Furthermore, it is assumed that an A-phase actuating signal applied to the individual electrode  231  positioned on the right side in the figure, and a D-phase actuating signal applied to the individual electrode  234  positioned on a back side of the individual electrode  231  relative to the piezoelectric element  220 , periodically change a voltage at the same phase. 
         [0063]      FIG. 4  is a diagram illustrating an example of wave patterns of actuating signals supplied to the vibration actuator unit  201 . As illustrated in the figure, the A-phase actuating signal and the D-phase actuating signal mutually synchronize. The B-phase actuating signal and the C-phase actuating signal also mutually synchronize. Furthermore, the A-phase actuating signal and the D-phase actuating signal have a phase 90-degree precedent to the B-phase actuating signal and the C-phase actuating signal. 
         [0064]      FIG. 5  is a schematic view explaining an actuation of the vibration actuator unit  201  when the aforementioned combination of the actuating signals is applied to the vibration actuator unit  201 . The same reference numerals are applied to elements in common with  FIG. 3  and overlapping descriptions are omitted. 
         [0065]    In  FIG. 4 , in the period when the phase of the A-phase actuating signal is  0  to 135 degrees and in the period of 315 degrees or more, voltages of the A-phase actuating signal and the D-phase actuating signal are higher than voltages of the B-phase actuating signal and the C-phase actuating signal. In such cases, as shown in  FIG. 5 , the piezoelectric material blocks  221 ,  224  are relatively longer than the piezoelectric material blocks  222 ,  223 , and the piezoelectric element  220  bends such that the contact portion  210  at the upper end is displaced rightward in the figure. 
         [0066]    Furthermore, in the period when the phase of the A-phase actuating signal is 135 to 315 degrees, the voltages of the B-phase actuating signal and the C-phase actuating signal are higher than the voltages of the A-phase actuating signal and the D-phase actuating signal. In such cases, the piezoelectric material blocks  222 ,  223  are relatively longer than the piezoelectric material blocks  221 ,  224 , and the piezoelectric element  220  bends such that the contact portion  210  at the upper end is displaced leftward in the figure. 
         [0067]    Moreover, in  FIG. 4 , in the period when the phase of the A-phase actuating signal is 90 to 180 degrees, voltage values of all actuating signals are positive. Furthermore, in the period when the phase of the A-phase actuating signal is 270 to 360 degrees, voltage values of all actuating signals are negative. Accordingly, the entire length of the piezoelectric element  220  is relatively larger in the former period than the latter period. 
         [0068]    To sum up these motions of the piezoelectric element  220 , when the actuating signals shown in  FIG. 4  are supplied to the vibration actuator unit  201 , the contact portion  210  performs an elliptic motion within a plane parallel to the arrow Y in the figure. Accordingly, in the stage apparatus  101 , the moving stage  130  which contacts the contact portion  210  performing the elliptic motion moves in the direction of the arrow Y in  FIG. 1 . Note that if a mutual delay relation of the actuating signals of two phases shown in  FIG. 4  is reversed, the moving direction of the moving stage  130  is reversed. 
         [0069]      FIG. 6  is a schematic side view of the vibration actuator unit  201 .  FIG. 6  shows the vibration actuator unit  201  seen from the direction indicated by the arrow Y in  FIG. 1  and  FIG. 2 , i.e., a plane direction of the individual electrodes  231 ,  234  and the common electrode  235 . The same reference numerals are applied to elements in common with  FIG. 2  and overlapping descriptions are omitted. 
         [0070]    Between each of the individual electrodes  231 ,  234  and the common electrode  235 , the piezoelectric element  220  is positioned. Here, it is assumed that an A-phase actuating signal applied to the individual electrode  231  positioned in the left side in the figure, and a B-phase actuating signal applied to the individual electrode  232  adjacent to the individual electrode  231  periodically change a voltage the same phase. Furthermore, it is assumed that a D-phase actuating signal applied to the individual electrode  234  positioned in the right side in the figure, and a C-phase actuating signal applied to the individual electrode  233  adjacent to the individual electrode  234  periodically change a voltage the same phase. 
         [0071]      FIG. 7  is a diagram illustrating an example of wave patterns of actuating signals supplied to the vibration actuator unit  201 . As illustrated in the figure, the A-phase actuating signal and the B-phase actuating signal mutually synchronize. The D-phase actuating signal and the C-phase actuating signal also mutually synchronize. Furthermore, the A-phase actuating signal and the B-phase actuating signal have a phase 90-degree precedent to the D-phase actuating signal and the C-phase actuating signal. 
         [0072]      FIG. 8  is a schematic view explaining motions of the vibration actuator unit  201  when the aforementioned combination of the actuating signals is applied to the vibration actuator unit  201 . The same reference numerals are applied to elements in common with  FIG. 6  and overlapping descriptions are omitted. 
         [0073]    In  FIG. 8 , in a period when the phase of the A-phase actuating signal is 0 to 135 degrees and in a period 315 degrees or more, voltages of the A-phase actuating signal and the B-phase actuating signal are higher than voltages of the D-phase actuating signal and the C-phase actuating signal. In such cases, as shown in  FIG. 8 , the piezoelectric material blocks  221 ,  222  are relatively longer than the piezoelectric material blocks  224 ,  223 , and the piezoelectric element  220  bends such that the contact portion  210  at the upper end is displaced leftward in the figure. 
         [0074]    Furthermore, in a period when the phase of the A-phase actuating signal is 135 to 315 degrees, the voltages of the D-phase actuating signal and C-phase actuating signal are higher than the voltages of the A-phase actuating signal and B-phase actuating signal. In such cases, the piezoelectric material blocks  221 ,  222  are relatively longer than piezoelectric material blocks  224 ,  223 , and the piezoelectric element  220  bends such that the contact portion  210  at the upper end is displaced rightward in the figure. 
         [0075]    Moreover, in  FIG. 7 , in a period when the phase of the A-phase actuating signal is 90 to 180 degrees, the voltage values of all actuating signal are positive. Furthermore, in a period when the phase of the A-phase actuating signal is 270 to 360 degrees, the voltage values of all actuating signal are negative. Accordingly, the entire length of the piezoelectric element  220  is relatively larger in the former period than the latter period. 
         [0076]    To sum up these motions of the piezoelectric element  220 , when the actuating signal shown in  FIG. 7  is supplied to the vibration actuator unit  201 , the contact portion  210  performs an elliptic motion within a plane parallel to the arrow X in the figure. Accordingly, in the stage apparatus  101 , the moving stage  130  which contacts the contact portion  210  performing an elliptic motion moves in the direction of the arrow X in  FIG. 1 . Furthermore, if a mutual delay relation of the actuating signals of two phases shown in  FIG. 7  is reversed, the moving direction of the moving stage  130  is reversed. 
         [0077]    As described above with reference to  FIG. 3  to  FIG. 8 , the vibration actuator unit  201  allows the moving stage  130  to move both in the direction of the arrow X and in the direction of the arrow Y. Moreover, by applying an actuating signal which is a superposition of the actuating signals shown in  FIG. 4  and the actuating signals shown in  FIG. 7 , to the vibration actuator unit  201 , the moving stage  130  can also move in a direction that the direction of the arrow X and the direction of the arrow Y are combined. 
         [0078]    In this manner, even though the vibration actuator unit  201  is a single actuator, it can move the moving stage  130  two-dimensionally by changing the combination of the actuating signals. Note that, even though  FIG. 1  depicts a single vibration actuator unit  201 , it is obvious that a plurality of vibration actuator units  201  may be provided. 
         [0079]      FIG. 9  is a schematic cross sectional view of a stage apparatus  102 . The stage apparatus  102  has, except for a portion which will be described later, the same structure as the stage apparatus  101  shown in  FIG. 1 . Thus, the same reference numeral as the stage apparatus  101  is applied to the common element, and overlapping descriptions are omitted. 
         [0080]    The stage apparatus  102  differs from the stage apparatus  101  in that it comprises a vibration actuator unit  202 . The vibration actuator unit  202  has a single support portion  114  on a lower surface in the figure, which protrudes downwardly. The support portion  114  contacts the upper surface of the base  110 , and supports and fixes the vibration actuator unit  202  at one point. 
         [0081]    Furthermore, the vibration actuator unit  202  has a pair of contact portions  210  on the upper surface in the figure. The moving stage  130  is biased downwardly by the biasing portions  120 , which is same as the vibration actuator unit  201 . Thereby, the pair of contact portions  210  respectively contacts the lower surface of the moving stage  130 , and supports the moving stage  130  from a downward side. 
         [0082]      FIG. 10  is a schematic exploded perspective view of the vibration actuator unit  202 . The vibration actuator unit  202  has a pair of contact portions  210 , a piezoelectric element divided into the plurality of piezoelectric material blocks  221 ,  222 ,  223 ,  224 , the common electrode  235  and the plurality of individual electrodes  231 ,  232 ,  233 ,  234 , respectively. In the vibration actuator unit  202 , each of the piezoelectric material blocks  221 ,  222 ,  223 ,  224  polarizes in a longitudinal direction, i.e., in a state shown in  FIG. 9 , in the direction indicated by the arrow X in the figure. 
         [0083]    In the vibration actuator unit  202 , a left-wing block  228  corresponding to a left half in the figure is separated by the individual electrodes  231 ,  232  and the common electrode  235  provided horizontally in the figure, to configure the pair of piezoelectric material blocks  221 ,  222  arranged vertically in the figure. In other words, the individual electrodes  231 ,  232  are arranged in an arrangement direction of the piezoelectric material blocks  221 ,  222 . 
         [0084]    Furthermore, in the vibration actuator unit  202 , a right-wing block  229  corresponding to a right half in the figure is separated by the individual electrodes  233 ,  234  and the common electrode  235  provided vertically in the figure, to configure the pair of piezoelectric material blocks  223 ,  224  arranged horizontally in the figure arrangement. In other words, the individual electrodes  233 ,  234  are arranged in an arrangement direction of the piezoelectric material blocks  223 ,  224 . 
         [0085]    Accordingly, for example, when a voltage is applied to one individual electrode  231 , an electric field strongly acts on the piezoelectric material block  221  corresponding to the individual electrode  231  such that the piezoelectric material block  221  extends or contracts. Likewise, when a voltage is applied to any of the other individual electrodes  232 ,  233 ,  234 , the corresponding piezoelectric material blocks  222 ,  223 ,  224  extend or contract. 
         [0086]    Thereby, when actuating voltages different from each other are applied to the individual electrodes  231 ,  232 , the left-wing block  228  of the vibration actuator unit  202  generates a mechanical vibration in the stage apparatus  102 , to bend within a plane normal to the outer surface of the base  110 . Furthermore, when actuating voltages different from each other are applied to the individual electrodes  233 ,  234 , the right-wing block  229  of the vibration actuator unit  202  generates a mechanical vibration in the stage apparatus  102 , to bend within a plane parallel to the outer surface of the base  110 . 
         [0087]    One of the pair of contact portions  210  is provided, in the individual electrode  231  positioned on the upper surface of the left-wing block  228 , at a center in a plane direction. The other contact portion  210  is provided approximately at a center of an upper surface formed when the individual electrodes  233 ,  234 , the piezoelectric material blocks  223 ,  224  and the common electrode  235  of the right-wing block  229  are in a tight contact with one another. These contact portions  210  are respectively vibrated together, when any one of the piezoelectric material blocks  221 ,  222  and the piezoelectric material blocks  223 ,  224  is vibrated. 
         [0088]    Note that, in the vibration actuator unit  202  in use, the contact portions  210 , the piezoelectric material blocks  221 ,  222 ,  223 ,  224 , the individual electrodes  231 ,  232 ,  233 ,  234  and the common electrode  235  in the figure are in a tight contact mutually. Such vibration actuator unit  202  is not necessarily produced of a combination of assemblies having a shape in the figure. For example, by layering piezoelectric materials and conductivity materials each of which has a layered shape one after another, the same structure as the vibration actuator unit  201  in the figure can be formed. 
         [0089]    Furthermore, when the aforementioned vibration actuator unit  202  is produced, after the piezoelectric material blocks  221 ,  222 ,  223 ,  224 , the individual electrodes  231 ,  232 ,  233 ,  234  and the common electrode  235  are assembled, the support portion  114  and the contact portion  210  may be adhesively attached. As a material of the support portion  114  and the contact portion  210 , for example, less deformable and anti-wearing POTICON (trade name) can be used. 
         [0090]      FIG. 11  is a diagram illustrating wave patterns of actuating signals applied to the individual electrodes  231 ,  232 ,  233 ,  234  of the vibration actuator unit  202 . Note that, as shown in  FIG. 10 , the A-phase actuating signal is applied to the individual electrode  231 , the B-phase actuating signal is applied to the individual electrode  232 , the C-phase actuating signal is applied to the individual electrode  233  and the D-phase actuating signal is applied to the individual electrode  234 , respectively. 
         [0091]    In the example illustrated in the figure, the A-phase actuating signal and the B-phase actuating signal have phases which differ by 180 degrees to each other, and the signal wave patterns which are mutually reversed. When such A-phase actuating signal and B-phase actuating signal are applied, the piezoelectric material blocks  221 ,  222  in the vibration actuator unit  202  generate, as mentioned above, a mechanical vibration to bend within a plane normal to the upper surface of the base  110  of the stage apparatus  102 . 
         [0092]    Meanwhile, the C-phase actuating signal and the D-phase actuating signal synchronize and have mutually the same signal wave pattern. When such C-phase actuating signal and D-phase actuating signal are applied, the piezoelectric material blocks  223 ,  224  in the vibration actuator unit  202  integrally extend and contract. In this case, the extending and contracting direction of the piezoelectric material blocks  223 ,  224  is the direction indicated by the arrow X in  FIG. 9  and  FIG. 10 . 
         [0093]    Moreover, in the wave patterns of actuating signals shown in  FIG. 11 , the phases of the A-phase actuating signal and the B-phase actuating signal are delayed by 90 degrees relative to the wave pattern of the C-phase actuating signal and the phase of the D-phase actuating signal. Accordingly, by combining a bending vibration of the piezoelectric material blocks  221 ,  222  within a vertical plane, and an extension and contraction of the piezoelectric material blocks  221 ,  222  in the longitudinal direction, the vibration actuator unit  202  can move, in the stage apparatus  102 , the moving stage  130  in the direction indicated by the arrow X in the figure. Note that, when a mutual delay relation of, shown in  FIG. 11 , the A-phase actuating signal and the B-phase actuating signal, and the C-phase actuating signal and the D-phase actuating signal is reversed, the moving direction of the moving stage  130  is reversed. 
         [0094]      FIG. 12  is a diagram illustrating other wave patterns of actuating signals applied to the individual electrodes  231 ,  232 ,  233 ,  234  of the vibration actuator unit  202 . In the example illustrated in the figure, the A-phase actuating signal and the B-phase actuating signal have phases which differ by 180 degrees from each other, and signal wave patterns which are mutually reversed. Accordingly, the piezoelectric material blocks  221 ,  222  generate a mechanical vibration, as mentioned above, to bend within a plane normal to the upper surface of the base  110  of the stage apparatus  102 . 
         [0095]    Furthermore, in the wave patterns of actuating signals shown in  FIG. 12 , the C-phase actuating signal and the D-phase actuating signal also have phases which differ by 180 degrees from each other, and signal wave patterns which are mutually reversed. Accordingly, the piezoelectric material blocks  223 ,  224  generate a mechanical vibration to bend within a plane parallel to the outer surface of the base  110  of the stage apparatus  102 . 
         [0096]    Moreover, in the wave patterns of actuating signals shown in  FIG. 12 , the phases of the A-phase actuating signal and the B-phase actuating signal are delayed by 90 degrees relative to the wave pattern of the C-phase actuating signal and the phase of the D-phase actuating signal. Accordingly, by combining a bending vibration of the piezoelectric material blocks  221 ,  222  within a vertical plane and a bending motion of the piezoelectric material blocks  223 ,  224  within a horizontal plane, the vibration actuator unit  202  moves, in the stage apparatus  102 , the moving stage  130  in a direction opposite to the direction indicated by the arrow Y in the figure. Note that, when a mutual delay relation shown in  FIG. 11  of the A-phase actuating signal and the B-phase actuating signal, and the C-phase actuating signal and the D-phase actuating signal is reversed, the moving direction of the moving stage  130  is reversed. 
         [0097]    As described with reference to  FIG. 9  to  FIG. 12 , the vibration actuator unit  202  can move the moving stage  130  both in the direction of the arrow X and in the direction of the arrow Y. Moreover, variable changes in the mutual delay relations of the A-phase to D-phase actuating signals can change the moving directions of the moving stage  130 . 
         [0098]    In this manner, even though the vibration actuator unit  202  is a single actuator, it can move the moving stage  130  two-dimensionally by changing the combination of the actuating signals. Even though the stage apparatus  102  in  FIG. 9  is provided with the single vibration actuator unit  201 , depending on an expected load, it is obvious that a plurality of vibration actuator units  202  may be provided. 
         [0099]      FIG. 13  is a schematic cross sectional view of a stage apparatus  103 . The stage apparatus  103  has, except for a portion which will be described later, the same structure as the stage apparatus  102  shown in  FIG. 9 . Thus, the same reference numeral as the stage apparatus  102  is applied to the common element, and overlapping descriptions are omitted. 
         [0100]    The stage apparatus  102  differs from the stage apparatus  102  in that it comprises a vibration actuator unit  203 . The vibration actuator unit  203  differs from the vibration actuator unit  202  in positions of the piezoelectric material blocks  221 ,  222 ,  223 ,  224  formed by the individual electrodes  231 ,  232 ,  233 ,  234  and the common electrode  235 . 
         [0101]      FIG. 14  is a schematic exploded perspective view of the vibration actuator unit  203 . The vibration actuator unit  203  has the pair of contact portions  210 , the piezoelectric element  220  divided into the plurality of piezoelectric material blocks, the common electrode  235  and the plurality of individual electrodes  231 ,  232 ,  233 ,  234 , respectively. In the vibration actuator unit  203 , each of the piezoelectric material blocks  221 ,  222 ,  223 ,  224  polarizes in a longitudinal direction, i.e., in a state shown in  FIG. 13 , in the direction indicated by the arrow X in the figure. 
         [0102]    In the vibration actuator unit  203 , the piezoelectric element  220  is separated, by the common electrode  235  provided in the longitudinal direction, into a pair of piezoelectric elements  220  aligned in a direction normal to the longitudinal direction. Moreover, in each of the pair of piezoelectric elements  220 , on a plane opposing the common electrode  235 , the four individual electrodes  231 ,  232 ,  233 ,  234  are provided which divide the plane in quarters longitudinally and laterally. 
         [0103]    Thereby, in the piezoelectric element  220  as a whole, the eight piezoelectric material blocks  221 ,  222 ,  223 ,  224  are formed to correspond to the eight individual electrodes  231 ,  232 ,  233 ,  234 . Each of the eight piezoelectric material blocks  221 ,  222 ,  223 ,  224  includes one of apexes of the piezoelectric element  220  which configures a hexahedron as a whole. 
         [0104]    Furthermore, of the eight individual electrodes  231 ,  232 ,  233 ,  234 , a pair having the same reference numeral is provided at diagonally opposing corners of the piezoelectric element  220  which configures a hexahedron as a whole, and receives the actuating signal of the same phase in common 
         [0105]    In the aforementioned vibration actuator unit  203 , the left-wing block  228  corresponding to a left half in the figure and the right-wing block  229  corresponding to a right half in the figure actuates in a similar manner with the vibration actuator unit  201  shown in  FIG. 2 , respectively. However, as these blocks are coupled in a rotating state around a common rotational axis in the longitudinal direction of the piezoelectric element  220 , the left half and the right half of the piezoelectric element  220  in the figure differ in their actuations. 
         [0106]    Thereby, in the vibration actuator unit  203 , when the actuating signal is supplied, an amplitude of a vibration generated in the piezoelectric element  220  is larger. Accordingly, in the stage apparatus  103 , the moving stage  130  is effectively actuated. 
         [0107]      FIG. 15  is a diagram illustrating a phase relation of the actuating signals applied to the individual electrodes  231 ,  232 ,  233 ,  234  of the vibration actuator unit  203 . Furthermore, in  FIG. 15 , signs of X and Y described in the upper row and the left column correspond to the arrow X and the arrow Y shown in  FIG. 13 , and indicate the moving directions of the moving stage  130  actuated by the vibration actuator unit  203 . As illustrated in the figure, by variously changing mutual delay relations of the A-phase to D-phase actuating signals, the moving direction of the moving stage  130  can be changed. 
         [0108]    As described with reference to  FIG. 13  to  FIG. 15 , the vibration actuator unit  203  actuates the eight piezoelectric material blocks  221 ,  222 ,  223 ,  224  with the actuating signals of four phases such that the moving stage  130  moves both in the direction of the arrow X and in the direction of the arrow Y. Furthermore, by changing mutual phase delay relations of the actuating signals, the moving direction of the moving stage  130  can be changed. 
         [0109]    In this manner, even though the vibration actuator unit  203  is a single actuator, by changing a combination of the actuating signals, it can move the moving stage  130  two-dimensionally. Even though the single vibration actuator unit  203  is provided in the stage apparatus  102  in  FIG. 9 , depending on an expected load, a plurality of vibration actuator unit  203  may be provided. 
         [0110]      FIG. 16  is a schematic cross sectional view of an optical apparatus  104 . The optical apparatus  104  comprises the vibration actuator unit  203 . Furthermore, the same reference numeral as the stage apparatus  103  shown in  FIG. 13  is applied to the common element, and overlapping descriptions are omitted. 
         [0111]    The optical apparatus  104  has a unique structure in that it comprises a moving axis  132 , instead of the moving stage  130  in the stage apparatus  102 . The moving axis  132  is inserted through a bearing portion  121  provided in the strut  122 , and supported by the base  110  slidably in the direction indicated by the arrow X in the figure. Furthermore, the moving axis  132  is supported at the bearing portion  121  rotatably around a central axis of the longitudinal direction. 
         [0112]    The moving axis  132  holds, at a holding frame  134  attached thereto outside the base  110  at one outer end, a lens  136  configuring a portion of an optical system. Accordingly, the lens  136  moves, when the moving axis  132  slides in the longitudinal direction, along an optical axis L parallel to the central axis of the moving axis  132 . 
         [0113]      FIG. 17  is a schematic perspective view of the optical apparatus  104 . The same reference numerals are applied to elements in common with  FIG. 16  and overlapping descriptions are omitted. Furthermore, in  FIG. 17 , the base  110  and the strut  122  are omitted. 
         [0114]    As illustrated in the figure, in the optical apparatus  104 , the contact portions  210  of the vibration actuator unit  203  contact a circumferential surface of the moving axis  132  of a cylindrical shape, and transmit an actuating force. Accordingly, when the vibration actuator unit  203  generates the actuating force in the direction of the arrow X shown in  FIG. 16 , the moving axis  132  moves in the direction of its central axis. 
         [0115]    Furthermore, in the optical apparatus  104 , when the vibration actuator unit  203  generates the actuating force in the direction of the arrow Y shown in  FIG. 16 , the moving axis  132  is rotated, as indicated by an arrow Q in  FIG. 17 , around its central axis. When the moving axis  132  is rotated, the lens  136  deviates from the optical axis L. 
         [0116]    In this manner, by using the vibration actuator unit  203 , the lens  136  of an optical member can move not only in the direction of the optical axis L, but also in a direction deviating from the optical axis L. Accordingly, in addition to changing a characteristic of the optical system by moving the lens  136 , the optical configuration as such can be changed by removing the lens  136  from the optical system. 
         [0117]    Note that, in the aforementioned example, the optical apparatus  104  has been formed by using the vibration actuator unit  203 . However, the optical apparatus  104  may be formed by using other vibration actuator units  201 ,  202  which have been already described. 
         [0118]      FIG. 18  is a schematic cross sectional view of an optical apparatus  105  and shows a cross section normal to the optical axis L of the optical system including the lens  136 . The same reference numerals are applied to elements in common with  FIG. 17  and overlapping descriptions are omitted. 
         [0119]    The optical apparatus  105  comprises a lens barrel  116 , flat springs  125 ,  127 , the holding frame  134 , the lens  136  and the vibration actuator units  203 . The holding frame  134  holding the lens  136  is coupled to the pair of flat springs  125 ,  127 . The individual vibration actuator unit  203  has the same structure as the vibration actuator unit  203  which has been already described, and can move in a vertical direction relative to the page, and in a direction parallel to the page, relative to an inner surface of the lens barrel  116 . 
         [0120]    The pair of flat springs  125 ,  127  is biased in an extending direction, and the respective end portions press the vibration actuator units  203  against the inner surface of the lens barrel  116 . Thereby, the holding frame  134  and the lens  136  are held at approximately a center of the lens barrel  116  in the figure. 
         [0121]    In the aforementioned optical apparatus  105 , when a portion of the vibration actuator units  203  move in the direction of the optical axis L, an inclination of the lens  136  relative to the optical axis L is changed. Furthermore, when all of the vibration actuator units  203  move in the direction of the optical axis L at the same time, the lens  136  translates in the direction of the optical axis L, while maintaining an angle relative to the optical axis L. Moreover, when all of the vibration actuator units  203  move parallel to the page at the same time, the lens  136  moves parallel to the page, while maintaining the inclination relative to the optical axis L, as indicated by the arrow X in the figure. 
         [0122]      FIG. 19  is a schematic cross sectional view explaining another operation of the optical apparatus  105  shown in  FIG. 18 . The same reference numerals are applied to elements in common with  FIG. 18  and overlapping descriptions are omitted. 
         [0123]    In the optical apparatus  105  shown in  FIG. 19 , the pair of vibration actuator units  203  provided in an upper side in the figure moves, as indicated by an arrow M 1  in the figure, in a mutually approaching direction and parallel to the page. Furthermore, the pair of vibration actuator units  203  provided in a lower side in the figure moves, as indicated by an arrow M 2  in the figure, in a mutually departing direction and parallel to the page. 
         [0124]    With aforementioned actuations of the vibration actuator units  203 , upper portions of the flat springs  125 ,  127  in the figure approach parallel to a lateral surface of the lens barrel  116 . Meanwhile, inclinations of lower portions of the flat springs  125 ,  127  in the figure are increased, relative to the lateral surface of the lens barrel  116 . Thereby, the lens  136  translates, as indicated by an arrow M 3  in the figure, toward a lower position within the lens barrel  116 . 
         [0125]    In this manner, the vibration actuator units  203  in the upper side in the figure and the vibration actuator units  203  in the lower side in the figure mutually actuate differently such that the lens  136  also moves vertically in the figure. Moreover, by combining the actuations of these vibration actuator units  203 , an optical adjustment of the lens  136  can be performed with an electrical control over the vibration actuator units  203 . 
         [0126]    Note that, in the aforementioned example, the optical apparatus  105  has been formed using the vibration actuator units  203 . However, the optical apparatus  105  may be formed using the other vibration actuator units  201 ,  202  which have been already described. 
         [0127]      FIG. 20  is schematic perspective view of an active rotating articulation apparatus  106 . The active rotating articulation apparatus  106  comprises the base  110 , the biasing portions  120 , an actuated spherical body  138  and the vibration actuator unit  203 . 
         [0128]    The vibration actuator unit  203  allows the support portion  114  to contact the upper surface of the base  110 , and is fixed to the base  110 . The actuated spherical body  138  contacts the contact portion  210  of the vibration actuator unit  203 , and is supported and fixed from a downward side in the figure. 
         [0129]    The biasing portions  120  comprises the strut  122  extending from base  110  upwardly in the figure, the elastic member  124  hung from the strut  122 , and the spherical seat  126  biased downwardly by the elastic member  124 . The spherical seat  126  biases the actuated spherical body  138  downwardly. Accordingly, the actuated spherical body  138  is pressed against the contact portion  210  of the vibration actuator unit  203 . 
         [0130]    In the aforementioned active rotating articulation apparatus  106 , when the vibration actuator unit  203  is actuated, the actuated spherical body  138  is rotated while maintaining the position unchanged. Thereby, a movable leg  139  attached to the actuated spherical body  138  changes an inclination relative to the base  110 . 
         [0131]    As already described, the vibration actuator unit  203  generates an actuating force in an optional direction for a plane direction of the base  110 . Accordingly, the active rotating articulation apparatus  106  can change, with an electrical control of an actuating power supplied to the vibration actuator unit  203 , the inclination of the movable leg  139 . 
         [0132]    Note that, in the aforementioned example, the active rotating articulation apparatus  106  has been formed using the vibration actuator unit  203 . However, the active rotating articulation apparatus  106  may be formed using the other vibration actuator units  201 ,  202  which have been already described. 
         [0133]      FIG. 21  is a schematic cross sectional view of a camera system  500 . The camera system  500  includes a lens unit  600  and a camera body  300 . 
         [0134]    Note that, in order to simplify the description, in the following description, a side on which a subject to be imaged by the camera system  500  is positioned will be described as a front side or a distal side. Furthermore, in the camera system  500 , a side on which the camera body  300  is positioned relative to the lens unit  600  will be described as a rear side or a back side. 
         [0135]    The lens unit  600  has a fixed cylinder  610 , lens groups  620 ,  630 ,  640 , a lens-side control portion  650  and a vibration actuator unit  400 . At a rear end of the fixed cylinder  610 , a lens-side mount portion  660  is provided. 
         [0136]    The lens-side mount portion  660  mate with a body-side mount portion  360  of the camera body  300  such that the lens unit  600  is coupled to the camera body  300 . As a coupling of the lens-side mount portion  660  and the body-side mount portion  360  can be released, the lens unit  600  can be replaced with another lens unit  600  having a lens-side mount portion  660  of the same standard. 
         [0137]    The lens groups  620 ,  630 ,  640  are positioned along an optical axis X inside the fixed cylinder  610 , and form an optical system. At least one lens group  630  is supported by a holding frame  632  having an interlocking portion  634  and an engaging portion  636 . 
         [0138]    The interlocking portion  634  interlocks with a guide axis  612 . Furthermore, the engaging portion  636  engages with the guide axis  612 . The guide axis  612  is provided parallel to the optical axis X of the optical system, and fixed to the fixed cylinder  610 . Accordingly, the holding frame  632  is slidably supported along the guide axis  612 . 
         [0139]    The holding frame  632  is integrally coupled to the vibration actuator unit  400 . The vibration actuator unit  400  includes the biasing portion  410  and the electromechanical converting element  420 . The biasing portion  410  presses the electromechanical converting element  420  against the guide axis  612 . The electromechanical converting element  420  generates a vibration with an actuating power supplied thereto, and generates an actuating force which moves the holding frame  632  along the guide axis  612 . 
         [0140]    Note that, to an inner surface of the fixed cylinder  610 , a magnetic sensor  430  provided opposing the vibration actuator unit  400  is fixed. The magnetic sensor  430  is used to detect positions of the biasing portion  410  and the electromechanical converting element  420 . 
         [0141]    The lens-side control portion  650  includes an actuating circuit which outputs an actuating power of the vibration actuator unit  400 , and performs an overall control over the lens unit  600 . Furthermore, the lens-side control portion  650  also performs a communication between a body-side control portion  322  mounted on the camera body  300  and the lens unit  600 . Thereby, the lens unit  600  loaded on the camera body  300  operates in cooperation with the camera body  300 . 
         [0142]    The camera body  300  comprises a mirror unit  370  on a rear side of the body-side mount portion  360 . The mirror unit  370  has a main mirror holding frame  372  and a main mirror  371 . The main mirror holding frame  372  is pivotally supported by a main mirror rotating axis  373 , while holding the main mirror  371 . 
         [0143]    Furthermore, the mirror unit  370  has a sub-mirror holding frame  375  and a sub-mirror  374 . The sub-mirror holding frame  375  is pivotally supported by the main mirror holding frame  372  via a sub-mirror rotating axis  376 , while holding the sub-mirror  374 . When the main mirror holding frame  372  rotates, the sub-mirror  374  and the sub-mirror holding frame  375  rotate relative to the main mirror holding frame  372 , while moving with the main mirror holding frame  372 . 
         [0144]    In the camera body  300 , above the mirror unit  370  in the figure, a focusing screen  352  and a pentaprism  354  are provided one after another. Furthermore, in the camera body  300 , behind the pentaprism  354  in the figure, a finder optical system  356  and a photometric sensor  390  are provided. A rear end of the finder optical system  356  is exposed as a finder  350 , through a back side of the camera body  300 . The photometric sensor  390  detects an intensity of an incident light. 
         [0145]    In the camera body  300 , behind the mirror unit  370  in the figure, a focal plane shutter  310 , an optical filter  332  and an imaging element  330  are provided one after another. The focal plane shutter  310  is opened and closed to open or shield the imaging element  330  against the incident light. 
         [0146]    The optical filter  332  is provided just in front of the imaging element  330  to remove an infrared light and an ultraviolet light from the light entering the imaging element  330 . Furthermore, the optical filter  332  protects an outer surface of the imaging element  330 . Moreover, the optical filter  332  includes a lowpass filter which reduces a space frequency of the incident light. Thereby, the optical filter  332  removes space frequency components exceeding the Nyquist frequency of the imaging element  330  from the incident light to inhibit an occurrence of a moire. 
         [0147]    The imaging element  330  is formed of a photoelectric converting element such as a CCD sensor and a CMOS sensor, and receives the light which enters through the optical filter  332 . Further behind the imaging element  330 , a substrate  320  and a back-side display portion  340  are provided one after another. In the substrate  320 , a body-side control portion  322 , an image processing portion  324  and the like are implemented. The back-side display portion  340  is formed of a liquid crystal display and the like, and exposed through the back side of the camera body  300 . 
         [0148]    The main mirror  371  in a state illustrated in the figure is at an observation position obliquely crossing the light entering through the lens unit  600 . The main mirror  371  has a reflecting area reflecting the incident light and a half mirror area allowing for a penetration of a portion of the incident light. 
         [0149]    A portion of a subject light entering the main mirror  371  at the observation position penetrates the half mirror area and enters the sub-mirror  374 . The sub-mirror  374  reflects the incident light downwardly in the figure such that the incident light enters a focusing sensor  382  through a focusing optical system  380  provided below the mirror unit  370  in the figure. 
         [0150]    Furthermore, the reflecting area of the main mirror  371  at the observation position reflects the light entering through the lens unit  600  toward the focusing screen  352 . The focusing screen  352  is provided at a position optically conjugate to an element arrangement surface of the imaging element  330 , and visualizes an image formed by the optical system of the lens unit  600 . The subject image produced on the focusing screen  352  is observed as an erect image from the finder  350  through the pentaprism  354  and the finder optical system  356 . 
         [0151]    A portion of the light emitted from the pentaprism  354  is received by the photometric sensor  390  provided above the finder optical system  356 . When a release button of the camera body  300  is in a half-pressed state, the photometric sensor  390  detects the light intensity of the received light. 
         [0152]    The body-side control portion  322  calculates a subject brightness in accordance with the detected light intensity, and calculates imaging conditions such as an aperture value, a shutter speed, an ISO sensitivity and the like, in accordance with the calculated subject brightness. Thereby, the camera system  500  can be in a state for imaging a subject under appropriate imaging conditions. 
         [0153]    Furthermore, when the release button of the camera body  300  is in the half-pressed state, the focusing sensor  382  detects a defocus amount in the optical system of the lens unit  600 , and notifies the body-side control portion  322 . The body-side control portion  322  calculates a moving amount of the lens group  630  enough to negate the sensed defocus amount, and notifies the lens-side control portion  650 . 
         [0154]    The lens-side control portion  650  allows the vibration actuator unit  400  to actuate and actuate the lens group  630 , in accordance with the notified moving amount. Thereby, the subject image formed by the optical system of the lens unit  600  is produced on the focusing screen  352  clearly. 
         [0155]    In the camera system  500 , when the release button is further pressed, the main mirror holding frame  372  rotates with main mirror  371  in a clockwise direction in the figure, and stops at an imaging position in an approximately horizontal state. Thereby, the main mirror  371  retreats from a path of the light entering through the optical system of the lens unit  600 . 
         [0156]    When the main mirror  371  rotates toward the imaging position, the sub-mirror holding frame  375  also moves upwardly with the main mirror holding frame  372 , rotates around the sub-mirror rotating axis  376 , and stops at the imaging position in an approximately horizontal state. Thereby, the sub-mirror  374  also retreats from the path of the incident light. 
         [0157]    When the main mirror  371  and the sub-mirror  374  move to the imaging position, subsequently, a front curtain of the focal plane shutter  310  is opened. Thereby, the light entering through the optical system of the lens unit  600  passes through the optical filter  332  and is received by the imaging element  330 , and imaging is performed. Then, a rear curtain of the focal plane shutter  310  is closed, the main mirror  371  and the sub-mirror  374  return to the observation position again, and a series of operations for imaging are completed. 
         [0158]    Note that, though the description has been given of an example of the vibration actuator unit  400  applied to the lens unit  600  in the camera system  500  of a single-lens reflex camera with interchangeable lenses, the vibration actuator unit  400  can be used for moving an optical member in a lens unit of various imaging apparatuses such as a mirrorless camera, a compact camera and a video camera. Besides, not only for an imaging apparatus, the vibration actuator unit  400  can be widely used for an optical apparatus such as a microscope comprising an optical member and for actuating a member which is positioned with a high positioning accuracy. Moreover, not only for an optical apparatus, the vibration actuator unit  400  can be used as an actuator of a stage apparatus and the like. 
         [0159]      FIG. 22  is a cross sectional view schematically illustrating a cross section normal to the optical axis X of the lens unit  600 . The same reference numerals are applied to elements in common with  FIG. 21  and overlapping descriptions are omitted. 
         [0160]    In the lens unit  600 , the holding frame  632  holding the lens group  630  integrally comprises the interlocking portion  634  at an upper end in the figure. The interlocking portion  634  encompasses the guide axis  612  with the electromechanical converting element  420 . Thereby, the holding frame  632  mates with the guide axis  612  in a rotatable state around guide axis  612 . 
         [0161]    Furthermore, the holding frame  632  integrally comprises the engaging portion  636  at a lower end in the figure. The engaging portion  636  has parallel surfaces having an interval approximately the same as an outer diameter of the guide axis  612  such that the guide axis  612  is sandwiched between the parallel surfaces. Thereby, a lower side of the holding frame  632  is prevented to be displaced parallel to the page and horizontally in the figure. Accordingly, with the interlocking portion  634  and the engaging portion  636 , the holding frame  632  is positioned in a direction parallel to the page. 
         [0162]    Note that the magnetic sensor  430  is fixed to an inner surface of fixed cylinder  610  to be opposing an upper surface of the biasing portion  410 . However, the biasing portion  410  moves, with the holding frame  632 , vertically relative to the page. Accordingly, in the direction vertical to the page, the magnetic sensor  430  and the biasing portion  410  are not necessarily opposing each other at the same position. 
         [0163]      FIG. 23  is a schematic view illustrating an overall structure of the vibration actuator unit  400 . The same reference numerals are applied to elements in common with  FIG. 21  and  FIG. 22 , and overlapping descriptions are omitted. 
         [0164]    The vibration actuator unit  400  has the biasing portion  410 , the electromechanical converting element  420  and the magnetic sensor  430 . Furthermore, the vibration actuator unit  400  in the lens unit  600  is supplied with an actuating power from the lens-side control portion  650 , and actuates under a control of the lens-side control portion  650 . 
         [0165]    The electromechanical converting element  420  has a support portion  422 , contacting portions  424  and a piezoelectric element  425 . The piezoelectric element  425  is formed from a piezoelectric material of a cuboid shape. The pair of contacting portions  424  is provided on a lower surface of the piezoelectric element  425  in the figure, and contacts the guide axis  612 , respectively. 
         [0166]    The support portion  422  is provided on an upper surface of the piezoelectric element  425  in the figure. The support portion  422  contacts the biasing portion  410  from a downward side in the figure, and receives a biasing force from the biasing portion  410 . Thereby, the electromechanical converting element  420  is biased downwardly in the figure such that the contacting portions  424  are pressed against the guide axis  612 . 
         [0167]    The biasing portion  410  includes a permanent magnet  412 , a yoke  414  and a buffer member  416 . The yoke  414  is formed from a magnetic body material, and provided along the upper surface to the lateral surface of the electromechanical converting element  420  in the figure. A lower end of the yoke  414  is close to, but does not contact the guide axis  612 . 
         [0168]    The permanent magnet  412  is provided, overlaid on the yoke  414 , in a direction such that a magnetic pole is arranged parallel to the guide axis  612 . Accordingly, the yoke  414  is also magnetized by the permanent magnet  412 . Note that, in the vibration actuator unit  400 , the guide axis  612  is also formed from a magnetic body and configures a portion of the biasing portion  410 . That is, the magnetic field generated by the permanent magnet  412  forms a magnetic circuit with the yoke  414  and the guide axis  612  each of which is a magnetic body. Thereby, the biasing portion  410  is attracted toward the guide axis  612 . 
         [0169]    A force attracting the biasing portion  410  toward the guide axis  612  is transmitted, as already described, through the support portion  422  to the electromechanical converting element  420  as a biasing force, and presses the contacting portions  424  against the guide axis  612 . Thus, in the vibration actuator unit  400  having the biasing portion  410 , with the magnetic force generated by the permanent magnet  412 , the electromechanical converting element  420  is pre-compressed toward the guide axis  612 . 
         [0170]    Note that, in the vibration actuator unit  400 , the buffer member  416  is loaded at a lower end of the yoke  414  to prevent the guide axis  612  from being scratched, when the lower end of the yoke  414  contacts the guide axis  612  for some reasons. Furthermore, by forming the buffer member  416  from a non-magnetic body, the buffer member  416  is prevented from being fastened to the guide axis  612  when contacting the guide axis  612 . In consideration of these functions, preferably, the buffer member  416  is formed using a resin material such as a POM resin having elastic and lubricating properties. 
         [0171]    In the vibration actuator unit  400 , the magnetic sensor  430  detects a magnetic force of the permanent magnet  412  of the biasing portion  410 , as a physical amount. Accordingly, when the biasing portion  410  and the electromechanical converting element  420  are displaced relative to the fixed cylinder  610 , the magnetic sensor  430  detects a change in the magnetic field. Thereby, the lens-side control portion  650  can recognize a position of the holding frame  632  based on a detection result of the magnetic sensor  430 . Accordingly, the lens-side control portion  650  can adjust an actuating power to be supplied to the vibration actuator unit  400  in accordance with the position of the holding frame  632 . 
         [0172]    Note that, as the magnetic sensor  430 , a Hall element, a magnetic impedance element and the like can be used. Furthermore, along the moving route of the vibration actuator unit  400 , a plurality of magnetic sensors  430  may be positioned. 
         [0173]    Moreover, even though in the example illustrated in the figure, the biasing portion  410  has the single permanent magnet  412 , a plurality of permanent magnets  412  may be provided on the yoke  414 . Thereby, in the magnetic sensor  430 , a periodical change in the magnetic flux density is detected such that a movement amount of the vibration actuator unit  400  is detected with a high accuracy. 
         [0174]    Moreover, in the biasing portion  410 , instead of the permanent magnet  412 , an electromagnet can be used. As the electromagnet can change a strength of the generated magnetic force, the biasing portion  410  using the electromagnet can change the biasing force. However, when the magnetic force of the electromagnet is changed, preferably, the detection result is corrected in accordance with a change in the generated magnetic force magnetic sensor  430 . 
         [0175]      FIG. 24  is a schematic view illustrating one of the electromechanical converting elements  420  enlarged and seen from the lateral surface. The same reference numerals are applied to elements in common with other figures and overlapping descriptions are omitted. 
         [0176]    Each of the electromechanical converting elements  420  has a pair of A-phase electrodes  421  and B-phase electrodes  423  provided at diagonally opposing corner positions of the piezoelectric element  425 , which configures an approximately rectangular shape when being seen from the lateral surface. The piezoelectric element  425  is formed from a piezoelectric material such as PZT. The A-phase electrodes  421  and the B-phase electrodes  423  are respectively formed from a metal material which has been processed through calcination with the piezoelectric element  425 . 
         [0177]    Note that piezoelectric element  425  may be formed by layering piezoelectric materials having a layered shape or may be in a bulk state. The dimension of the piezoelectric element  425  formed in this manner may be, for example, about  2  mm on a side, by layering about  10  layers of layered-shape piezoelectric materials. 
         [0178]    The A-phase electrodes  421  and the B-phase electrodes  423  are also provided, in a direction vertical to the page, at the corresponding positions on a back surface of the piezoelectric element  425 . Accordingly, when an actuating voltage is applied to the A-phase electrodes  421 , in an area between the A-phase electrodes  421 , the piezoelectric element  425  contracts or extends. Likewise, when an actuating voltage is applied to the B-phase electrodes  423 , in an area between the B-phase electrodes  423 , the piezoelectric element  425  contracts or extends. 
         [0179]      FIG. 25  is a wave pattern diagram illustrating signal wave patterns of the A-phase actuating signal and the B-phase actuating signal supplied to the electromechanical converting element  420 . As illustrated in the figure, the A-phase actuating signal and the B-phase actuating signal are periodically varied. When the A-phase actuating signal has, for example, an electric vibration forming a wave pattern of a sine wave, the B-phase actuating signal generates a sine wave pattern delayed by 90 degrees relative to the A-phase actuating signal, i.e., a voltage signal modulated with a modulation signal having a cosine wave pattern, as the B-phase actuating signal. 
         [0180]      FIG. 26  is a schematic view illustrating an actuation of the electromechanical converting element  420  which is supplied with the aforementioned A-phase actuating signal and B-phase actuating signal. As described above, as the A-phase actuating signal and the B-phase actuating signal have mutually different phases, in the area provided with the A-phase electrodes  421  and in the area provided with the B-phase electrodes  423 , the piezoelectric element  425  shows different extended and contracted states. 
         [0181]    In the electromechanical converting element  420 , as the A-phase electrodes  421  and the B-phase electrodes  423  are provided adjacent to one another, the aforementioned extension and contraction of the piezoelectric element  425  allow the electromechanical converting element  420  to generate a bending deformation. Furthermore, the electromechanical converting element  420  also generates a deformation at the same time such that the dimension in the longitudinal direction extends and contracts. Thereby, as indicated by an arrow V in the figure, an elliptic vibration is generated such that the contacting portions  424  draw an elliptic orbit in the figure. 
         [0182]    Turning back to  FIG. 23 , the contacting portions  424  of the electromechanical converting element  420  are pressed against the guide axis  612  with the biasing force applied by the biasing portion  410 . Accordingly, when the contacting portions  424  generate the aforementioned elliptic vibration, the guide axis  612  is relatively displaced relative to the electromechanical converting element  420 . 
         [0183]    Note that, in view of the aforementioned actions of the electromechanical converting element  420 , preferably, the contacting portions  424  is positioned at anti-node portions of the vibration generated in the electromechanical converting element  420 . Thereby, the actuating force generated by the elliptic vibration of the electromechanical converting element  420  is effectively transmitted to the guide axis  612 . 
         [0184]    In the aforementioned vibration actuator unit  400 , the vibration actuator unit  400  integrally moving with the holding frame  632  contacts the guide axis  612  at the contacting portions  424  generating an actuating force, and does not at any other portions. Accordingly, in accordance with the movement of the holding frame  632  actuated by the vibration actuator unit  400 , no slide resistance is generated such that the holding frame  632  is smoothly actuated. 
         [0185]    Furthermore, in the vibration actuator unit  400 , by detecting the magnetic flux density of the magnetic field generated by the permanent magnet  412  which is a portion of the biasing portion  410 , an actuating amount of the vibration actuator unit  400  can be detected. Accordingly, without an assembly which occupies a space and costs much such as a linear scale, the actuation amount of the vibration actuator unit  400  can be detected with a high accuracy. 
         [0186]    Note that, in the aforementioned example, the permanent magnet  412  is provided in the yoke  414  which moves with the piezoelectric element  425  side. However, a structure is acceptable in which the permanent magnet  412  is provided on the guide axis  612  side to attract the yoke  414  formed by the magnetic body with a magnetic force and generate a biasing force. With such a structure, by positioning the magnetic sensor  430  on the piezoelectric element  425  side, the actuation amount of the vibration actuator unit  400  can be detected. 
         [0187]      FIG. 27  is a cross sectional view of another lens unit  601  comprising the vibration actuator unit  400 , and shows a cross section normal to the optical axis X. The same reference numerals are applied to elements in common with the embodiments shown in  FIG. 26  or the other preceding figures, and overlapping descriptions are omitted. 
         [0188]    The lens unit  601  comprises a pair of vibration actuator units  400 . Furthermore, the fixed cylinder  610  has, instead of the guide axis  612 , a guide rail  611  integrally formed with the fixed cylinder  610 . The guide rail  611  extends in a direction vertical to the page, i.e., in a direction parallel to the optical axis X of the lens unit  601 , with the cross section in a constant shape. 
         [0189]    Thereby, the guide rail  611  forms a pair of flat guide surfaces  613  in the longitudinal direction of the lens unit  601 . The pair of guide surfaces  613  has mutually different inclinations relative to a horizontal line in the figure. 
         [0190]    Each of the pair of vibration actuator units  400  contacts the pair of guide surfaces  613 . Here, in each of the vibration the actuator units  400 , as already described, the magnetic force generated by the permanent magnet  412  of the biasing portion  410  presses the contacting portions  424  against the guide surfaces  613  in mutually different directions. Accordingly, the holding frame  632  is positioned, by the pair of vibration actuator units  400  respectively generating adsorption forces to the pair of guide surfaces  613 , relative to the fixed cylinder  610  in any directions in the cross section illustrated in the figure. 
         [0191]    In other words, in the lens unit  601 , the holding frame  632  and the fixed cylinder  610  contact each other at the vibration actuator units  400 , and do not at any other portions. Accordingly, when the holding frame  632  is actuated with the actuating forces of the vibration actuator units  400 , no slide resistance is generated in accordance with the movement of the holding frame  632  such that the holding frame  632  smoothly moves. 
         [0192]    Furthermore, each of the pair of vibration actuator units  400  can detect individually the moving amount with a high accuracy, with the magnetic sensors  430 . Accordingly, the actuations of the pair of vibration actuator units  400  can be synchronized to move the holding frame  632  without an inclination relative to the optical axis X. 
         [0193]      FIG. 28  is a schematic plan view of the stage apparatus  450  comprising the vibration actuator units  401 ,  402 . The stage apparatus  450  comprises a plate  452 , a moving stage  454  and an actuating portion  456 . 
         [0194]    In the stage apparatus  450 , the moving stage  454  is provided, via the actuating portion  456 , on the fixed plate  452 . The moving stage  454  is actuated by the actuating portion  456  to move in a plane direction of the plate  452 , relative to the plate  452 . 
         [0195]    The actuating portion  456  has the plurality of vibration actuator units  401 ,  402 . The individual structure of the vibration actuator units  401 ,  402  is approximately equivalent to the vibration actuator unit  400  shown in  FIG. 23 . However, the magnetic sensors  430  are embedded in the plate  452  at positions opposing the permanent magnet  412 , respectively. 
         [0196]    Furthermore, in the actuating portion  456 , a pair of vibration actuator units  401  is provided parallel to a direction indicated by the arrow Y in the figure. Another vibration actuator unit  402  is provided, as indicated by the arrow X in the figure, in a direction normal to the vibration actuator units  401 . These vibration actuator units  401 ,  402  are integrally coupled to each other with a coupling member  440 , and further mount the moving stage  454 . Accordingly, the moving stage  454  moves on the plate  452  with the actuating portion  456 , in accordance with the actions of the actuating portion  456 . 
         [0197]    In the aforementioned stage apparatus  450 , the pair of vibration actuator units  401  is actuated synchronously, and generates the actuating force in the same direction such that the moving stage  454  is translated in the directions indicated by the arrows Y and -Y in the figure. Furthermore, by actuating the another vibration actuator unit  402  to generate the actuating force, the moving stage  454  can be translated in the directions indicated by the arrows X and −X in the figure. 
         [0198]    Moreover, in the stage apparatus  450 , when the pair of vibration actuator units  401  is actuated differently from each other, as indicated by arrows θ and −θ in the figure, the moving stage  454  can be rotated. In this manner, by combining the plurality of vibration actuator units  401 ,  402  to form the actuating portion  456 , the stage apparatus  450  can be formed with a simplified structure and a high functionality. 
         [0199]      FIG. 29  and  FIG. 30  are a schematic cross sectional view of another stage apparatus  451 .  FIG. 29  shows a cross section of the moving stage  454  taken along the moving direction, and  FIG. 30  shows a cross section normal to the cross section in  FIG. 29 , respectively. The stage apparatus  451  comprises the plate  452 , a vibration actuator unit  403  and the moving stage  454 . 
         [0200]    In the stage apparatus  451 , the moving stage  454  is supported by the vibration actuator unit  403  on the fixed plate  452 . Thereby, the moving stage  454  is actuated by the vibration actuator unit  403  to move relative to the plate  452  in a plane direction of the plate  452 . 
         [0201]    The vibration actuator unit  403  has the biasing portion  410  and the electromechanical converting element  420 . The structure of the electromechanical converting element  420  is equivalent to the vibration actuator unit  400  illustrated in  FIG. 23 . Accordingly, the common reference numerals are applied to the same element, and overlapping descriptions are omitted. 
         [0202]    The biasing portion  410  has a communication hole  411  having an opening just close to the plate  452 . The communication hole  411  is coupled to a vacuum source through the flexible tube  413 . Thereby, a negative pressure is also generated at an opening at a lower end of the communication hole  411  to vacuum an outer surface of the plate  452 . 
         [0203]    In this manner, the biasing portion  410  generates a biasing force to press the contacting portions  424  of the electromechanical converting element  420  against the plate  452 . Thereby, when the electromechanical converting element  420  operates, mechanical vibrations of the contacting portions  424  generate an actuating force between the plate  452  and the vibration actuator unit  403  such that the moving stage  454  moves on the plate  452 . 
         [0204]    Furthermore, in the stage apparatus  451 , the plate  452  has a slit  453 , a cavity  455  and a pressure sensor  432 . The cavity  455  is a hollow space formed inside the plate  452 , and allows the slit  453  and the pressure sensor  432  to be in communication with each other. The pressure sensor  432  is, a left edge in the figure, i.e., at a biased position relative to the moving direction of moving stage  454 , in communication with the cavity  455 . 
         [0205]    The slit  453  allows the cavity  455  and outside of the plate  452  to be in communication. Furthermore, the slit  453  is provided, on the outer surface of the plate  452 , at a position opposing the opening of the communication hole  411 . Accordingly, when the communication hole  411  is in communication with the vacuum source, the communication hole  411  also vacuums an inner air in the slit  453 . Thereby, an air in the cavity  455  is also vacuumed such that the pressure in the cavity  455  is also reduced. 
         [0206]    The pressure sensor  432  detects a change in an air pressure in such cavity  455 . 
         [0207]    Moreover, when the vibration actuator unit  403  is actuated and the moving stage  454  moves on the plate  452 , the position at which the communication hole  411  and the slit  453  are opposing is changed such that a distance D between the communication hole  411  and the pressure sensor  432  is changed. As the inner air in the cavity  455  has a viscosity, in accordance with a change in the distance D, a pressure in the cavity  455  detected by the pressure sensor  432  differs. More specifically, when the distance D is smaller, the reduced pressure detected by the pressure sensor  432  is larger, and when the distance D is larger, the reduced pressure detected by the pressure sensor  432  is smaller. 
         [0208]    In this manner, also in the stage apparatus  451 , the vibration actuator unit  403  detects the air pressure which is the physical amount generated by the biasing portion  410  to sense the moving amount. Accordingly, without additional members such as a linear scale and an encoder, the moving amount can be monitored such that the control is performed with a good accuracy. 
         [0209]    Note that, also in the stage apparatus  451 , like the stage apparatus  450  illustrated in  FIG. 28 , the actuating portion  456  having a plurality of vibration actuator units  403  oriented in mutually different directions may be provided. Thereby, the moving stage  454  can move two-dimensionally on a plane parallel to the outer surface of the plate  452 , and can be rotated on the same plane. 
         [0210]    While the embodiment(s) of the present invention has (have) been described, the technical scope of the invention is not limited to the above described embodiment(s). It is apparent to persons skilled in the art that various alterations and improvements can be added to the above-described embodiment(s). It is also apparent from the scope of the claims that the embodiments added with such alterations or improvements can be included in the technical scope of the invention.