Patent Publication Number: US-2022214558-A1

Title: Optical unit and imaging device

Description:
TECHNICAL FIELD 
     The present disclosure relates to an optical unit and an imaging device. More specifically, the present disclosure relates to an optical unit that drives a lens barrel, and an imaging device including the optical unit. 
     BACKGROUND ART 
     In the related art, an optical unit including a lens barrel having an optical system, such as a lens, disposed therein has been used in an imaging device such as a camera. In the optical unit, the focal position of a subject can be adjusted by adjusting the positions of the optical system and the lens barrel. Such position adjustment for the lens barrel or the like can be performed by displacing the lens barrel or the like using a driving element that expands and contracts in accordance with a voltage to be applied. An electrostrictive polymer actuator can be used as the driving element. The electrostrictive polymer actuator is a driving element configured such that a polymer elastomer is disposed between two electrodes. The electrostrictive polymer actuator expands and contracts by applying a voltage between the two electrodes to generate a Coulomb force and deform the polymer elastomer. 
     As such an optical unit, for example, an optical unit in which a driving element configured in a cylindrical shape is disposed on an end face of a lens barrel on an imaging surface side is used (see, for example, PTL 1). In the optical unit, the driving element supports the lens barrel and supplies a driving power source to the driving element, so that the driving element expands in an optical axis direction and drives the lens barrel in the optical axis direction. In addition, the lens barrel can also be inclined by dividing the driving element into a plurality of elements and individually applying drive power sources to the elements to drive the elements. 
     CITATION LIST 
     Patent Literature 
     [PTL 1] 
     
         
         JP 2009-069588A 
       
    
     SUMMARY 
     Technical Problem 
     In the above-described related art, there is a problem in that a driving speed of the lens barrel is low. Because of a configuration in which the driving element is disposed only on the end face of the lens barrel on the imaging surface side, there is a problem in that a driving force is insufficient and a driving speed is reduced. 
     The present disclosure is contrived in view of the above-described problems, and an object thereof is to improve a driving speed of a lens barrel in an optical unit. 
     Solution to Problem 
     The present disclosure is contrived in view of the above-described problems, and a first aspect thereof is an optical unit including a lens barrel that includes an imaging optical system, a housing that includes a front supporting portion and a rear supporting portion in order to support the lens barrel, the front supporting portion being disposed at a front in a direction toward a subject along an optical axis of the imaging optical system, and the rear supporting portion being disposed at a rear with an orientation opposite to being at the front, a front driving portion that connects the lens barrel and the front supporting portion and drives the lens barrel, and a rear driving portion that connects the lens barrel and the rear supporting portion and drives the lens barrel. 
     Further, in the first aspect, the front driving portion and the rear driving portion may be driven by displacing the lens barrel. 
     Further, in the first aspect, a driving element that displaces the lens barrel may be disposed in the front driving portion and the rear driving portion. 
     Further, in the first aspect, the driving element may be constituted by a piezoelectric element. 
     Further, in the first aspect, a plurality of the driving elements may be disposed in the front driving portion and the rear driving portion. 
     Further, in the first aspect, the rear driving portion may be configured such that a plurality of driving elements are disposed at positions facing the plurality of driving elements of the front driving portion. 
     Further, in the first aspect, the rear driving portion may be configured such that a plurality of driving elements are disposed at positions shifted from the plurality of driving elements of the front driving portion. 
     Further, in the first aspect, the front driving portion and the rear driving portion may be disposed obliquely with respect to the optical axis. 
     Further, in the first aspect, the lens barrel may include a driving portion connection portion to which the front driving portion and the rear driving portion are connected. 
     Further, in the first aspect, at least one of the front driving portion and the rear driving portion may also shield incident light. 
     In addition, a second aspect of the present disclosure is an imaging device including an imaging element, a lens barrel that includes an imaging optical system that forms an image of a subject on the imaging element, a housing that includes a front supporting portion and a rear supporting portion in order to support the lens barrel, the front supporting portion being disposed at a front in a direction toward a subject along an optical axis of the imaging optical system, and the rear supporting portion being disposed at a rear with an orientation opposite to being at the front, a front driving portion that connects the lens barrel and the front supporting portion and drives the lens barrel, and a rear driving portion that connects the lens barrel and the rear supporting portion and drives the lens barrel. 
     Adopting such aspects leads to an effect that a lens barrel is driven by a front driving portion and a rear driving portion. It is assumed that a driving force is transmitted from each of a front direction and a rear direction. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram showing a configuration example of an imaging device according to an embodiment of the present disclosure. 
         FIG. 2  is a cross-sectional view showing a configuration example of an imaging device according to a first embodiment of the present disclosure. 
         FIG. 3  is a diagram showing an example of the arrangement of driving elements according to the first embodiment of the present disclosure. 
         FIG. 4  is a diagram showing an example of the arrangement of driving elements according to a modification example of the first embodiment of the present disclosure. 
         FIG. 5  is a diagram showing an example of the arrangement of driving elements according to a second embodiment of the present disclosure. 
         FIG. 6  is a diagram showing an example of the arrangement of driving elements according to a modification example of the second embodiment of the present disclosure. 
         FIG. 7  is a diagram showing another example of the arrangement of driving elements according to a modification example of the second embodiment of the present disclosure. 
         FIG. 8  is a cross-sectional view showing a configuration example of an imaging device according to a third embodiment of the present disclosure. 
         FIG. 9  is a diagram showing an example of the arrangement of driving elements according to a fourth embodiment of the present disclosure. 
         FIG. 10  is a diagram showing an example of the arrangement of driving elements according to a fifth embodiment of the present disclosure. 
         FIG. 11  is a block diagram showing a schematic configuration example of a camera which is an example of a device to which the present technique is applicable. 
         FIG. 12  is a diagram showing an example of a method of adjusting an optical axis according to an embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Next, embodiments for implementing the present disclosure (hereinafter, referred to as embodiments) will be described with reference to the drawings. In the following drawings, the same or similar portions are denoted by the same or similar reference numerals and signs. In addition, embodiments will be described in the following order. 
     1. First Embodiment 
     2. Second Embodiment 
     3. Third Embodiment 
     4. Fourth Embodiment 
     5. Fifth Embodiment 
     6. Sixth Embodiment 
     1. First Embodiment 
     [Configuration of Imaging Device] 
       FIG. 1  is a diagram showing a configuration example of an imaging device according to an embodiment of the present disclosure. A in the drawing is a top view showing a configuration example of an imaging device  10 , and B in the drawing is a side view showing a configuration example of the imaging device  10 . The imaging device  10  in the drawing includes a substrate  11 , an optical unit  100 , a control unit  200 , a signal cable  15 , and a connector  16 . 
     The substrate  11  is a substrate on which an imaging element  12  to be described later, the optical unit  100 , and the control unit  200  are mounted. A wiring that transmits signals of the imaging element  12  and the like is disposed in the substrate  11 . 
     The optical unit  100  forms an image of a subject in the imaging element  12  and protects the imaging element  12 . The optical unit  100  includes a lens barrel  110  and a housing  120 . 
     The lens barrel  110  includes an optical system such as a lens to form an image of a subject in the imaging element  12 . The lens barrel  110  in the drawing shows an example of a lens barrel configured in a cylindrical shape. 
     The housing  120  holds the lens barrel  110  and covers the imaging element  12 . An opening portion  121  is disposed at the center portion of the upper surface of the housing  120 . The lens barrel  110  is disposed to pass through the opening portion  121 . In addition, a driving portion that drives the lens barrel  110  is disposed in the housing  120 . 
     The control unit  200  controls the driving portion of the housing  120 . The control unit  200  performs control by outputting a driving signal to the above-described driving portion. In addition, the control unit  200  can also control the imaging element  12  and process an image signal which is generated by the imaging element  12 . 
     The signal cable  15  transmits a signal such as an image signal. The signal cable  15  in the drawing is constituted by a plurality of signal lines and is connected to the wiring of the substrate  11 . A connector  16  for connection to equipment such as a camera is disposed in the signal cable  15  in the drawing. 
     [Cross-Sectional Configuration of Imaging Device] 
       FIG. 2  is a cross-sectional view showing a configuration example of an imaging device according to a first embodiment of the present disclosure. In the drawing, the imaging device  10  includes the imaging element  12 , the lens barrel  110 , the housing  120 , a front driving portion  130 , and a rear driving portion  140 . Meanwhile, in the drawing, the signal cable  15  and the connector  16  are not shown. 
     The imaging element  12  is a semiconductor element that generates and outputs an image signal corresponding to incident light. The imaging element  12  is constituted by a semiconductor chip and is mounted as a bare chip on the substrate  11 . Specifically, the imaging element  12  is bonded to the substrate  11  and is connected to a pad (not shown) formed in the substrate  11  by a bonding wire  13 . The pad is connected to the wiring of the substrate  11 . 
     The lens barrel  110  is disposed between a subject and the imaging element  12  and forms an image of the subject on a light receiving surface of the imaging element  12 . The lens barrel  110  in the drawing is configured in a cylindrical shape as described above, and shows an example in which a plurality of lenses  112  are disposed as an optical system. The position of the optical system of the lens barrel  110  is adjusted to an optical axis that passes through the center portion of the imaging element  12  from the subject. In addition, a disk-like driving portion connection portion  111  is disposed at an end of the lens barrel  110  on the imaging element  12  side. The driving portion connection portion  111  is a portion to which a driving portion to be described later is connected. 
     The housing  120  is disposed to be adjacent to the substrate  11  and is disposed at a position surrounding the imaging element  12 . The housing  120  in the drawing shows an example in which a top plate and a bottom plate are attached to a side plate  122  having a shape surrounding the imaging element  12 . The top plate is disposed on the upper surface of the housing  120 . The opening portion  121  is formed in the top plate, and the above-described lens barrel  110  passes therethrough. On the other hand, the bottom plate is disposed on the bottom surface of the housing  120 . An opening portion  125  is formed in the bottom plate, and the imaging element  12  is disposed on the substrate  11  at a position adjacent to the opening portion  125 . The bottom plate can be bonded to the substrate  11  using, for example, an adhesive. The top plate is disposed at a position closer to a subject in the housing  120 , and the bottom plate is disposed at a position closer to the imaging element  12  in the housing  120 . Here, a direction toward the subject in the optical axis of the optical system of the lens barrel  110  and a direction toward the imaging element  12  are assumed to be forward and rearward, respectively. The top plate and the bottom plate are respectively disposed at the front and rear of the housing  120 . 
     A top plate portion in the vicinity of the opening portion  121  constitutes a front supporting portion  123  for supporting the lens barrel  110 . The front driving portion  130  to be described later is connected to the front supporting portion  123 . The front supporting portion  123  supports the lens barrel  110  through the front driving portion  130 . On the other hand, the bottom plate portion in the vicinity of the opening portion  125  constitutes a rear supporting portion  124  for supporting the lens barrel  110 . The rear driving portion  140  to be described later is connected to the rear supporting portion  124 . The rear supporting portion  124  supports the lens barrel  110  through the rear driving portion  140 . The front supporting portion  123  and the rear supporting portion  124  are respectively disposed at the front and the rear of the housing  120  and support the lens barrel  110 . 
     The front driving portion  130  connects the lens barrel  110  and the front supporting portion  123  of the housing  120 . In addition, the front driving portion  130  further performs the driving of the lens barrel  110 . Specifically, the front driving portion  130  can displace and drive the lens barrel  110  by expanding and contracting by itself. The front driving portion  130  in the drawing is constituted by a plurality of driving elements  131  to  134 . In the drawing, the driving elements  131  and  133  are shown. The driving element  131  and the like can be constituted by, for example, a piezoelectric element. The piezoelectric element is an element configured by sandwiching a piezoelectric material such as ceramic between two electrodes. The piezoelectric element can be contracted by applying a voltage between the two electrodes. In addition, it is also possible to use a piezoelectric element using a polymer elastomer instead of ceramic. In addition, the piezoelectric element can also be expanded by reversing the polarity of a voltage to be applied between the two electrodes depending on the type of piezoelectric material. 
     The rear driving portion  140  connects the lens barrel  110  and the rear supporting portion  124  of the housing  120 . In addition, the rear driving portion  140  further performs the driving of the lens barrel  110 . Similarly to the front driving portion  130 , the rear driving portion  140  can drive the lens barrel  110  by expanding and contracting by itself. The rear driving portion  140  in the drawing is constituted by a plurality of driving elements  141  to  144 . In the drawing, the driving elements  141  and  143  are shown. Similarly to the driving element  131  and the like, the driving element  141  and the like can be constituted by a piezoelectric element. Meanwhile, a wiring not shown in the drawing is connected to the driving element  131  and the like and the driving element  141  and the like, and a driving signal is transmitted through the wiring. A voltage based on the driving signal is applied to electrodes of the driving element  131  and the like. 
     The front driving portion  130  and the rear driving portion  140  are connected to the driving portion connection portion  111  of the lens barrel  110 . The driving element  131  and the like constituting the front driving portion  130  are connected to a surface of the driving portion connection portion  111  on the front side. On the other hand, the driving element  141  and the like constituting the rear driving portion  140  are connected to a surface of the driving portion connection portion  111  on a rear side. In this manner, the lens barrel  110  is held by the housing  120  through the front driving portion  130  and the rear driving portion  140 . The arrangement of the driving element  131  and the like and the arrangement of the driving element  141  and the like will be described in detail. 
     In the drawing, the lens barrel  110  can be displaced forward by contracting the front driving portion  130  (the driving elements  131  to  134  to be described later in  FIG. 3 ), and the lens barrel  110  can be displaced backward by contracting the rear driving portion  140  (the driving elements  141  to  144  to be described later in  FIG. 3 ). In addition, the lens barrel  110  can be displaced backward by expanding the front driving portion  130 , and the lens barrel  110  can be displaced forward by expanding the rear driving portion  140 . Thereby, a focal position of a subject can be adjusted. 
     Further, in a case where the front driving portion  130  is contracted and the rear driving portion  140  is expanded, a driving force to be applied to the lens barrel  110  can be substantially doubled. Similarly, when the front driving portion  130  is expanded, and the rear driving portion  140  is contracted, a driving force to be applied to the lens barrel  110  can also be improved. Thereby, the speed of displacement of the lens barrel  110  can be improved. 
     In addition, the driving element positioned diagonally to the lens barrel  110  is expanded and contracted, and thus the lens barrel  110  can be displaced in an inclination direction. Specifically, the lens barrel  110  can be inclined in the oblique right direction in the drawing by contracting the driving element  131  and the driving element  143 . At this time, a driving force to be applied to the lens barrel  110  can be improved by expanding the driving element  133  and the driving element  141 . In addition, the lens barrel  110  can be inclined in the oblique left direction in the drawing by contracting the driving element  133  and the driving element  141 . 
     Note that the front driving portion  130  and the rear driving portion  140  in the drawing are disposed obliquely with respect to the optical axis of the optical system. Specifically, the driving elements  131  to  134  are disposed in an oblique direction from the front supporting portion  123  to the driving portion connection portion  111  and in a direction approaching the optical axis. Similarly, the driving elements  141  to  144  are disposed in an oblique direction from the rear supporting portion  124  to the driving portion connection portion  111  and in a direction approaching the optical axis. Thereby, the lens barrel  110  can be displaced in a direction perpendicular to the optical axis. Specifically, the lens barrel  110  can be displaced to the left in the drawing by contracting the driving element  131  and the driving element  141 , and the lens barrel  110  can be displaced to the right in the drawing by contracting the driving element  133  and the driving element  143 . In addition, the lens barrel  110  can be displaced to the right in the drawing by expanding the driving element  131  and the driving element  141 , and the lens barrel  110  can be displaced to the left in the drawing by expanding the driving element  133  and the driving element  143 . 
     Note that, when the lens barrel  110  is displaced to the left, a driving force can be improved by contracting the driving element  131  and the driving element  141  and expanding the driving element  133  and the driving element  143 . Similarly, when the lens barrel  110  is displaced to the right, a driving force can be improved by expanding the driving element  131  and the driving element  141  and contracting the driving element  133  and the driving element  143 . In this manner, the lens barrel  110  can be displaced in a direction perpendicular to the optical axis by obliquely disposing the front driving portion  130  and the rear driving portion  140 . 
     In this manner, the lens barrel  110  is driven using the driving element  131  and the like, and thus it is possible to achieve miniaturization of and low-power consumption in the imaging device  10 , as compared to a case where a mechanical component such as a motor is used. 
     Note that the configuration of the imaging device  10  is not limited to this example. For example, the driving portion connection portion  111  can also be disposed at a center portion on the side surface of the lens barrel  110 . In addition, the front driving portion  130  and the rear driving portion  140  can also be directly connected to the side surface of the lens barrel  110  by omitting the driving portion connection portion  111 . Even in such a case, the front driving portion  130  and the rear driving portion  140  are naturally disposed on the front and rear sides, respectively. 
     [Arrangement of Driving Elements] 
       FIG. 3  is a diagram showing an example of the arrangement of the driving elements according to the first embodiment of the present disclosure. The drawing shows the optical unit  100  which is seen from the front, and shows an example of the arrangement of the driving elements  131  to  134  and the driving elements  141  to  144 . In the drawing, a rectangle indicated by an alternating two dots-dashed line represents an end of the side plate  122  of the housing  120 . A circle indicated by a solid line represents the opening portion  121  of the top plate of the housing  120  and represents an end of the front supporting portion  123 . A circle indicated by an alternating dotted-dashed line represents the opening portion  125  of the bottom plate of the housing  120  and represents an end of the rear supporting portion  124 . A circle indicated by a dashed line represents the driving portion connection portion  111  of the lens barrel  110 . 
     A in the drawing is a diagram showing the arrangement of the driving elements  131  to  134 . In A of the drawing, a region surrounded by a broken line indicates each of the driving elements  131  to  134 . As shown in A of the drawing, the driving elements  131  to  134  are disposed at intervals of 90 degrees on a circumference along the front supporting portion  123  and the driving portion connection portion  111 . 
     B in the drawing is a diagram showing the arrangement of the driving elements  141  to  144 . In B of the drawing, a region surrounded by a broken line indicates each of the driving elements  141  to  144 . As shown in B of the drawing, the driving elements  141  to  144  are disposed at intervals of 90 degrees on a circumference along the rear supporting portion  124  and the driving portion connection portion  111  at positions overlapping the driving elements  131  to  134 . In this manner, the driving elements  141  to  144  are disposed at positions facing the driving element  131  to  144  with the driving portion connection portion  111  interposed therebetween. 
     In the drawing, the direction of the optical axis is assumed to be a z-axis. The lens barrel  110  can be displaced forward along the z-axis by contracting the driving elements  131  to  134  and expanding the driving elements  141  to  134  as described above. In addition, the lens barrel  110  can be displaced backward along the z-axis by expanding the driving elements  131  to  134  and contracting the driving elements  141  to  134  as described above. 
     In addition, the horizontal direction of the paper in the drawing is assumed to be an x-axis, and toward the right side and the left side in the drawing are assumed to be positive and negative directions, respectively. In addition, the vertical direction of the paper in the drawing is assumed to be a y-axis, and toward the upper side and the lower side in the drawing are assumed to be positive and negative directions, respectively. The lens barrel  110  can be displaced in the positive direction of the x-axis by expanding the driving element  131  and the driving element  141  and contracting the driving element  133  and the driving element  143  as described above. In addition, the lens barrel  110  can be displaced in the negative direction of the x-axis, for example, by contracting the driving element  131  and the driving element  141  and expanding the driving element  133  and the driving element  143 . 
     In addition, the lens barrel  110  can be displaced in the positive direction of the y-axis, for example, by contracting the driving element  132  and the driving element  142  and expanding the driving element  134  and the driving element  144 . In addition, the lens barrel  110  can be displaced in the negative direction of the y-axis, for example, by expanding the driving element  132  and the driving element  142  and contracting the driving element  134  and the driving element  144 . 
     In addition, the lens barrel  110  can be inclined in the positive direction of the x-axis by expanding the driving element  131  and the driving element  143  and contracting the driving element  133  and the driving element  141  as described above. In addition, the lens barrel  110  can be inclined in the negative direction of the x-axis by contracting the driving element  131  and the driving element  143  and expanding the driving element  133  and the driving element  141  as described above. Thereby, the lens barrel  110  can be displaced in a rotation direction ( 3  direction) along the y-axis. 
     In addition, the lens barrel  110  can be inclined in the positive direction of the y-axis, for example, by contracting the driving element  132  and the driving element  144  and expanding the driving element  134  and the driving element  142 . In addition, the lens barrel  110  can be inclined in the negative direction of the y-axis, for example, by expanding the driving element  132  and the driving element  144  and contracting the driving element  134  and the driving element  142 . Thereby, the lens barrel  110  can be displaced in a rotation direction (a direction) along the x-axis. 
     In addition, the lens barrel  110  can be displaced in the upper right direction in the drawing by contracting the driving element  132  and  133  and the driving element  142  and  143  and expanding the driving element  134  and  131  and the driving element  144  and  141 . In addition, the displacement of the driving elements  131  to  134  and the driving elements  141  to  144  can be adjusted by adjusting a voltage to be applied. In this manner, the optical unit  100  in the drawing can displace the lens barrel  110  in any direction except for rotation along the z-axis. 
     The driving of the lens barrel  110  by the front driving portion  130  and the rear driving portion  140  can be performed when the adjustment of a focal position of a subject during imaging and camera shake correction are performed. In addition, tilt imaging and the like can be performed by driving the lens barrel  110 . In addition, the tilt imaging and the like can also be performed when an optical axis is adjusted in the manufacturing process for the imaging device  10 . 
     Modification Example 
     The optical unit  100  described above includes the driving elements  131  to  134  and the driving elements  141  to  144 , but the arrangement of the driving elements can also be changed. 
       FIG. 4  is a diagram showing an example of the arrangement of driving elements according to a modification example of the first embodiment of the present disclosure. Similarly to  FIG. 3 ,  FIG. 4  is a diagram showing an optical unit  100  which is seen from the front. The optical unit  100  is different from the optical unit  100  in  FIG. 3  in that the driving element  134  and the driving element  144  are omitted. 
     In A of the drawing, driving elements  131  to  133  are disposed at intervals of 120 degrees on a circumference along the front supporting portion  123  and the driving portion connection portion  111 . Further, in B of the drawing, driving elements  141  to  143  can be disposed at intervals of 120 degrees on a circumference along the rear supporting portion  124  and the driving portion connection portion  111  at positions overlapping the driving elements  131  to  133 . 
     As described above, the imaging device  10  according to the first embodiment of the present disclosure connects the lens barrel  110  to the housing  120  by the front driving portion  130  and the rear driving portion  140  and drives the lens barrel  110 . It is possible to drive and displace the lens barrel  110  from both the front and the rear and improve a driving force. A driving speed can be improved. 
     2. Second Embodiment 
     In the imaging device  10  according to the above-described first embodiment, the driving element  131  and the like constituting the front driving portion  130  and the driving element  141  and the like constituting the rear driving portion  140  are disposed at positions overlapping each other when seen in a top view. On the other hand, an imaging device  10  according to the second embodiment of the present disclosure is different from that in the above-described first embodiment in that driving elements constituting a front driving portion  130  and a rear driving portion  140  are disposed at positions shifted from each other when seen in a top view. 
     [Arrangement of Driving Elements] 
       FIG. 5  is a diagram showing an example of the arrangement of driving elements according to the second embodiment of the present disclosure. Similarly to  FIG. 3 ,  FIG. 5  is a diagram showing an optical unit  100  which is seen from the front and is a diagram showing an example of the arrangement of driving elements  131  and the like, and a driving element  141  and the like. The optical unit  100  is different from the optical unit  100  described in  FIG. 3  in that driving elements  133  and  134  and driving elements  143  and  144  are omitted, and the driving element  131  and the like, and the driving element  141  and the like are disposed at positions shifted from each other. 
     In A of the drawing, the driving elements  131  and  132  are disposed at positions facing each other with a lens barrel  110  interposed therebetween. That is, the driving elements  131  and  132  are disposed at intervals of 180 degrees on a circumference along a front supporting portion  123  and a driving portion connection portion  111 . 
     In B of the drawing, the driving elements  141  and  142  are disposed at positions facing each other with the lens barrel  110  interposed therebetween, similar to the driving elements  131  and  132 . The driving elements  141  and  142  are disposed at intervals of 180 degrees on a circumference along a rear supporting portion  124  and a driving portion connection portion  111  at positions shifted from the driving elements  131  and  132  by 90 degrees. That is, the driving elements  141  and  142  are disposed at positions shifted from the driving elements  131  and  132  in a circumferential direction of the lens barrel  110 . In this manner, the lens barrel  110  are supported at four points, that is, the driving elements  131  and  132  and the driving elements  141  and  142 . Thereby, the position and inclination of the lens barrel  110  can be stabilized. 
     The lens barrel  110  can be displaced to the front along the z-axis, for example, by contracting the driving elements  131  and  132  and expanding the driving elements  141  and  142 . In addition, the lens barrel  110  can be displaced to the rear along the z-axis, for example, by expanding the driving elements  131  and  132  and contracting the driving elements  141  and  142 . 
     In addition, the lens barrel  110  can be rotated in an a direction by expanding and contracting any one of the driving elements  131  and  132 . In addition, the lens barrel  110  can be rotated in a  8  direction by expanding and contracting any one of the driving elements  141  and  142 . 
     Modification Example 
     The above-described optical unit  100  includes the driving elements  131  and  132  and the driving elements  141  and  142 , but the number of driving elements can also be increased. 
       FIG. 6  is a diagram showing an example of the arrangement of driving elements according to a modification example of the second embodiment of the present disclosure. Similarly to  FIG. 5 ,  FIG. 6  is a diagram showing the optical unit  100  which is seen from the front. The optical unit  100  is different from the optical unit  100  in  FIG. 5  in that the driving element  133  and the driving element  143  are added. 
     In A of the drawing, the driving elements  131  to  133  are disposed at intervals of 120 degrees on a circumference along the front supporting portion  123  and the driving portion connection portion  111 . Further, in B of the drawing, the driving elements  141  to  143  are disposed at intervals of 120 degrees on a circumference along the rear supporting portion  124  and the driving portion connection portion  111  at positions shifted from the driving elements  131  to  133  by 60 degrees. 
     A displacement range of the lens barrel  110  can be widened by increasing the number of driving elements to be disposed. For example, the lens barrel  110  can be displaced in the upper right direction in the drawing by contracting the driving elements  132  and  133  and the driving element  142  and expanding the driving elements  131  and the driving elements  143  and  141 . 
       FIG. 7  is a diagram showing another example of the arrangement of driving elements according to a modification example of the second embodiment of the present disclosure. The optical unit  100  is different from the optical unit  100  in  FIG. 5  in that the driving elements  133  and  134  and the driving elements  143  and  144  are added. 
     In A of the drawing, the driving elements  131  to  134  are disposed at intervals of 90 degrees on a circumference along the front supporting portion  123  and the driving portion connection portion  111 . Further, in B of the drawing, the driving elements  141  to  144  are disposed at intervals of 90 degrees on a circumference along the rear supporting portion  124  and the driving portion connection portion  111  at positions shifted from the driving elements  131  to  134  by 45 degrees. 
     The number of driving elements to be disposed is further increased, and thus it is possible to finely adjust the displacement of the lens barrel  110 . 
     The other configurations of the imaging device  10  are similar to the configurations of the imaging device  10  described in the first embodiment of the present disclosure, and thus description thereof will be omitted. 
     As described above, in the imaging device  10  according to the second embodiment of the present disclosure, the number of driving elements constituting the front driving portion  130  can be reduced, and the configuration of the imaging device  10  can be simplified. 
     3. Third Embodiment 
     In the imaging device  10  according to the above-described first embodiment, the front driving portion  130  and the rear driving portion  140  are disposed obliquely with respect to the optical axis of the optical system. On the other hand, an imaging device  10  according to a third embodiment of the present disclosure is different from that in the above-described first embodiment in that a front driving portion  130  and a rear driving portion  140  are disposed in parallel with an optical axis. 
     [Configuration of Cross-Section of Imaging Device] 
       FIG. 8  is a cross-sectional view showing a configuration example of the imaging device according to the third embodiment of the present disclosure. Similarly to  FIG. 2 ,  FIG. 8  shows a configuration example of the imaging device  10 . The imaging device  10  is different from the imaging device  10  described in  FIG. 2  in that the front driving portion  130  and the rear driving portion  140  are disposed in a direction parallel to a lens barrel  110 . 
     The front driving portion  130  in the drawing is constituted by driving elements  331  to  334  (driving elements  332  and  334  are not shown in the drawing). The driving elements  331  to  334  are disposed in a direction parallel to the lens barrel  110  between a front supporting portion  123  and a driving portion connection portion  111  and connect the front supporting portion  123  and the lens barrel  110  to each other. In addition, the rear driving portion  140  in the drawing is constituted by driving elements  341  to  344  (driving elements  342  and  344  are not shown in the drawing). The driving elements  341  to  344  are disposed in a direction parallel to the lens barrel  110  between the rear supporting portion  124  and the driving portion connection portion  111  and connect the rear supporting portion  124  and the lens barrel  110  to each other. It is possible to displace the lens barrel  110  in a z-axis direction and to rotate the lens barrel  110  in a and  8  directions by the front driving portion  130  and the rear driving portion  140 . 
     In this manner, the front driving portion  130  and the rear driving portion  140  in the drawing are disposed in a direction parallel to an optical axis of an optical system of the lens barrel  110  and drive the lens barrel  110 . It is not necessary to dispose driving elements constituting the front driving portion  130  and the like in an oblique direction, and thus a manufacturing process for the optical unit  100  can be simplified. 
     The other configurations of the imaging device  10  are similar to the configurations of the imaging device  10  described in the first embodiment of the present disclosure, and thus description thereof will be omitted. 
     As described above, in the imaging device  10  according to the third embodiment of the present disclosure, the front driving portion  130  and the rear driving portion  140  are disposed in a direction parallel to the optical axis of the lens barrel  110 . Thereby, it is possible to simplify a manufacturing process for the optical unit  100  of the imaging device  10 . 
     4. Fourth Embodiment 
     The imaging device  10  according to the above-described first embodiment performs the displacement of the lens barrel  110  in the x, y, z, α, and β directions. On the other hand, an imaging device  10  according to a fourth embodiment of the present disclosure is different from that in the above-described first embodiment in that the displacement of the lens barrel  110  in a θ direction is further performed. 
     [Arrangement of Driving Elements] 
       FIG. 9  is a diagram showing an example of the arrangement of driving elements according to the fourth embodiment of the present disclosure. Similarly to  FIG. 3 ,  FIG. 9  is a diagram showing an optical unit  100  which is seen from the front and is a diagram showing an example of the arrangement of a driving element  131  and the like, and a driving element  141  and the like. The optical unit  100  is different from the optical unit  100  described in  FIG. 3  in that protrusion portions  126  and  114  are respectively disposed in a housing  120  and a driving portion connection portion  111 , and driving elements  151  and  152  are further disposed. 
     In the housing  120  in the drawing, two protrusion portions  126  are disposed in a side plate  122 . The protrusion portions  126  are disposed at positions symmetrical to the optical axis of the side plate  122 . Further, in the driving portion connection portion  111  in the drawing, two protrusion portions  114  are disposed. The protrusion portions  114  are disposed at positions symmetrical to the optical axis of the driving portion connection portion  111 . 
     The driving elements  151  and  152  are disposed between the protrusion portion  126  of the side plate  122  and the protrusion portion  114  of the driving portion connection portion  111 , and displace the lens barrel  110  in a rotation direction ( 0  direction) with respect to the optical axis. The driving elements  151  and  152  are disposed such that the direction of expansion and contraction is parallel to the tangent line of the outer circumference of the driving portion connection portion  111 . In addition, the driving elements  151  and  152  are disposed at positions symmetrical to the optical axis and drive the lens barrel  110  in a rotation direction. In the drawing, the lens barrel  110  can be displaced counterclockwise by contracting the driving elements  151  and  152 , and the lens barrel  110  can be displaced clockwise by expanding the driving elements  151  and  152 . It is possible to perform 6-axis displacement of the lens barrel  110  in the x, y, z, α, β and θ directions by adding the driving elements  151  and  152 . 
     Note that the configuration of the imaging device  10  is not limited to this example. For example, it is also possible to adopt a configuration in which three or less driving elements  131  and the like, and three or less driving elements  141  and the like are disposed. 
     The other configurations of the imaging device  10  are similar to the configurations of the imaging device  10  described in the first embodiment of the present disclosure, and thus description thereof will be omitted. 
     As described above, the imaging device  10  according to the fourth embodiment of the present disclosure can further perform the displacement of the lens barrel  110  in the θ direction by disposing the driving elements  151  and  152  such that the direction of expansion and contraction is parallel to the tangent line of the outer circumference of the driving portion connection portion  111 . 
     5. Fifth Embodiment 
     The imaging device  10  according to the above-described second embodiment includes the driving elements  131  to  134  and the driving elements  141  to  144 . On the other hand, an imaging device  10  according to a fifth embodiment of the present disclosure is different from that in the above-described second embodiment in that the imaging device  10  includes a driving element that shields incident light. 
     [Arrangement of Driving Elements] 
       FIG. 10  is a diagram showing an example of the arrangement of driving elements according to the fifth embodiment of the present disclosure. Similarly to  FIG. 7 ,  FIG. 10  is a diagram showing the optical unit  100  which is seen from the front and is a diagram showing an example of the arrangement of driving elements. The optical unit  100  is different from the optical unit  100  described in  FIG. 7  in that driving elements  135  to  138  and driving elements  145  to  148  are disposed instead of the driving elements  131  to  134  and the driving elements  141  to  144 . 
     The driving elements  135  to  138  constitute a front driving portion  130 . The driving elements  135  to  138  drive the lens barrel  110  and shield incident light. In addition, the driving elements  145  to  148  constitute a rear driving portion  140  and are disposed at positions shifted from the driving elements  135  to  138 . The driving elements  145  to  148  drive the lens barrel  110  and shield incident light. The driving elements  135  to  138  and the driving elements  145  to  148  are disposed to shield light, and thus light incident into the optical unit  100  through a gap between a housing  120  and the lens barrel  110  in an opening portion  121  can be reduced. For example, a piezoelectric element using a polymer elastomer in which a light-shielding material is dispersed can be used for the driving elements  135  to  138  and the driving elements  145  to  148 . In addition, as shown in the drawing, a light-shielding ability can be improved by using the driving elements  135  to  138  and the driving elements  145  to  148  configured to have a wider area than the driving element  131  and the like shown in  FIG. 7 . 
     Note that the configuration of the imaging device  10  is not limited to this example. Fr example, the sizes of the driving elements  135  to  138  and the like can also be changed so that the driving elements have shapes in contact with adjacent driving elements. In addition, any one of the driving elements  135  to  138  and the driving elements  145  to  148  can also be replaced with a driving element that does not have a light-shielding ability. 
     The other configurations of the imaging device  10  are similar to the configurations of the imaging device  10  described in the second embodiment of the present disclosure, and thus description thereof will be omitted. 
     As described above, in the imaging device  10  according to the fifth embodiment of the present disclosure, the driving elements  135  to  138  and the driving elements  145  to  148  are disposed to shield incident light. Thereby, it is possible to prevent the leakage of incident light to an imaging element  12  and to prevent the deterioration of an image quality. 
     Note that the driving elements  151  and  152  according to the fourth embodiment may be combined with the optical units  100  according to the first to third embodiments. In addition, similarly to the driving elements  135  to  138  and the driving elements  145  to  148  according to the fifth embodiment, a driving element that shields incident light may be applied as the driving elements of the optical units  100  according to the first to third embodiments. 
     Sixth Embodiment 
     The technique according to the present disclosure (the present technique) can be applied to various products. For example, the present technique may be realized as an imaging device mounted on a camera and the like. 
     [Configuration of Camera] 
       FIG. 11  is a block diagram showing a schematic configuration example of a camera which is an example of a device to which the present technique is applicable. A camera  1  in the drawing includes an imaging device  10  and a recording unit  5 . In the imaging device  10  in the drawing, a housing  120  is not shown. 
     The recording unit  5  is a unit in which images generated by the imaging device  10  are recorded. A storage device such as a semiconductor memory or a hard disk can be used as the recording unit  5 . 
     A control unit  200  in the drawing includes an imaging control unit  201 , an image processing unit  202 , and a lens barrel driving unit  203 . 
     The imaging control unit  201  is a unit that controls imaging in the imaging device  10 . The imaging control unit  201  controls imaging by outputting a control signal to the imaging element  12  and the image processing unit  202 . For example, a control signal for causing the imaging element  12  to start imaging can be generated and output on the basis of a signal received from an input device (not shown) such as a push button switch. The imaging element  12  to which the control signal is input generates and outputs an image signal after a predetermined exposure period has elapsed. In addition, the imaging control unit  201  can output a control signal to a lens barrel driving unit  203  to be described later and can control the lens barrel driving unit  203 . For example, the imaging control unit  201  can generate a control signal for displacing the lens barrel  110  to the front or the rear with respect to an optical axis and can output the generated control signal to the lens barrel driving unit  203  during imaging, and can adjust a focal position of a subject. 
     The lens barrel driving unit  203  is a unit that drives the lens barrel  110 . The lens barrel driving unit  203  drives the lens barrel  110  by generating and outputting driving signals of the driving elements constituting the front driving portion  130  and the rear driving portion  140 . In addition, the lens barrel driving unit  203  holds correction values of driving signals of a driving element  131  and the like and a driving element  141  and the like constituting the front driving portion  130  and the rear driving portion  140 . The correction value is an initial value of a control signal for displacing the lens barrel  110  in order to adjust the optical axis of the lens barrel  110 . For example, a correction value is output to be superimposed on a driving signal when the lens barrel  110  is displaced to the front and the rear in order to adjust a focal position of a subject. Thereby, it is possible to adjust the focal position while holding a state where the optical axis of the lens barrel  110  has been adjusted. 
     The image processing unit  202  processes an image signal generated by the imaging element  12 . The image processing unit  202  processes an image signal on the basis of a control signal received from the imaging control unit  201 . The processing of the image signal corresponds to, for example, processing for generating an image from the image signal. In addition, the generated image is output to the recording unit  5  described above. In addition, the image processing unit  202  can also perform processing for evaluating a generated image. The evaluation is processing for determining whether or not an optical axis is required to be adjusted by detecting a defect or the like of an image. For example, the image processing unit  202  can determine that an optical axis is required to be adjusted in a case where blurring or the like has been detected in a peripheral portion of an image. At this time, the image processing unit  202  calculates a correction value of the position of the lens barrel  110  and outputs the correction value to the lens barrel driving unit  203 . The correction value held in the lens barrel driving unit  203  described above is updated by the output correction value. The optical axis can be adjusted by such processing. 
     In a manufacturing process for the imaging device  10 , the optical axis of the lens barrel  110  can be adjusted. As the adjustment, for example, the adjustment of the lens barrel  110  in the x-axis, y-axis, and z-axis and the adjustment of a rotation angle in the α and β directions can be performed. In addition, the adjustment of the optical axis can be performed by displacing the lens barrel  110  on the basis of a known method such as active alignment. A driving signal corresponding to the displacement of the lens barrel  110  based on adjustment corresponds to an initial value of the above-described correction value. 
     In addition, it is also possible to adjust an optical axis after the use of the imaging device  10  is started. For example, in a case where the optical axis deviates due to a change in the shape of the housing  120  due to external factors, the optical axis can be adjusted in a state where the imaging device is mounted on a product. 
     [Adjustment of Optical Axis] 
       FIG. 12  is a diagram showing an example of a method of adjusting an optical axis according to an embodiment of the present disclosure. The drawing is a diagram showing an example of a method of adjusting an optical axis in the imaging device  10 . Processing in the drawing is performed on the assumption that an optical axis is adjusted when imaging is performed in the imaging device  10 . 
     First, the imaging element  12  performs the imaging of a subject. An image signal generated by the imaging is transmitted to the image processing unit  202 . This is performed on the basis of a control signal received from the imaging control unit  201  (step S 901 ). Next, the image processing unit  202  forms an image on the basis of the transmitted image signal and evaluates whether or not correction is required (step S 902 ). As a result of the evaluation, in a case where correction is required (step S 903 : Yes), the image processing unit  202  generates a correction value (step S 904 ). The generated correction value is output to the lens barrel driving unit  203 . Next, the lens barrel driving unit  203  holds the output correction value, generates a driving signal based on the correction value, and outputs the driving signal to the front driving portion  130  and the rear driving portion  140  (step S 905 ). Thereafter, the processing proceeds to the process of step S 901 . 
     On the other hand, as a result of the evaluation, in a case where it is determined in step S 903  that correction is not required (step S 903 : No), the image processing unit  202  outputs an image to the recording unit  5  to record the image in the recording unit  5  (step S 906 ). By the above-described procedure, it is possible to perform imaging and processing for adjusting an optical axis. 
     Finally, the description of each of the above-described embodiments is an example of the present disclosure, and the present disclosure is not limited to the above-described embodiments. Therefore, it goes without saying that various changes can be made according to the design and the like within the scope without departing from the technical idea according to the present disclosure even in other than this embodiment. 
     Additionally, the effects described in the present specification are merely exemplary and not limited. Further, other effects may be obtained. 
     The drawings in the above-described embodiment are schematic, and the dimensional ratios and the like of each part do not always match the actual ones. In addition, it is needless to say that drawings include portions where dimensional relationships and ratios differ between the drawings. 
     In addition, the processing procedures in the above-described embodiments may be ascertained as methods including the series of procedures or may be ascertained as a program that causes a computer to perform the series of procedures or a recording medium that stores the program. As the recording medium, for example, a compact disc (CD), a digital versatile disc (DVD), a memory card, or the like can be used. 
     Further, the present technique can have the following configurations. 
     (1) An optical unit including:
 
a lens barrel that includes an imaging optical system;
 
a housing that includes a front supporting portion and a rear supporting portion in order to support the lens barrel, the front supporting portion being disposed at a front in a direction toward a subject along an optical axis of the imaging optical system, and the rear supporting portion being disposed at a rear with an orientation opposite to being at the front;
 
a front driving portion that connects the lens barrel and the front supporting portion and drives the lens barrel; and a rear driving portion that connects the lens barrel and the rear supporting portion and drives the lens barrel.
 
(2) The optical unit according to (1), wherein the front driving portion and the rear driving portion are driven by displacing the lens barrel.
 
(3) The optical unit according to (2), wherein a driving element that displaces the lens barrel is disposed in the front driving portion and the rear driving portion.
 
(4) The optical unit according to (3), wherein the driving element is constituted by a piezoelectric element.
 
(5) The optical unit according to (3), wherein a plurality of the driving elements are disposed in the front driving portion and the rear driving portion.
 
(6) The optical unit according to (5), wherein the rear driving portion is configured such that the plurality of driving elements are disposed at positions facing the plurality of driving elements of the front driving portion.
 
(7) The optical unit according to (5), wherein the rear driving portion is configured such that the plurality of driving elements are disposed at positions shifted from the plurality of driving elements of the front driving portion.
 
(8) The optical unit according to any one of (1) to (7), wherein the front driving portion and the rear driving portion are disposed obliquely with respect to the optical axis.
 
(9) The optical unit according to any one of (1) to (8), wherein the lens barrel includes a driving portion connection portion to which the front driving portion and the rear driving portion are connected.
 
(10) The optical unit according to any one of (1) to (9), wherein at least one of the front driving portion and the rear driving portion further shields incident light.
 
(11) An imaging device including:
 
an imaging element;
 
a lens barrel that includes an imaging optical system that forms an image of a subject on the imaging element;
 
a housing that includes a front supporting portion and a rear supporting portion in order to support the lens barrel, the front supporting portion being disposed at a front in a direction toward a subject along an optical axis of the imaging optical system, and the rear supporting portion being disposed at a rear with an orientation opposite to being at the front;
 
a front driving portion that connects the lens barrel and the front supporting portion and drives the lens barrel; and a rear driving portion that connects the lens barrel and the rear supporting portion and drives the lens barrel.
 
     REFERENCE SIGNS LIST 
     
         
           1  Camera 
           10  Imaging device 
           12  Imaging element 
           100  Optical unit 
           110  Lens barrel 
           111  Driving portion connection portion 
           120  Housing 
           123  Front supporting portion 
           124  Rear supporting portion 
           130  Front driving portion 
           131  to  138 ,  141  to  148 ,  151 ,  152 ,  331  to  334 ,  341  to  344  Driving element 
           140  Rear driving portion 
           200  Control unit 
           201  Imaging control unit 
           202  Image processing unit 
           203  Lens barrel driving unit