Abstract:
Disclosed is a lens driving device includes: a lens frame; a support frame that elastically supports the lens frame in the optical-axis direction through plate springs; a base support member that elastically supports the lens frame supported by the support frame, in a direction intersecting the optical axis, through support wires; and a driving unit that drives the lens frame in one or both of the optical-axis direction and the direction intersecting the optical axis. The plate springs include elastic arm sections, respectively, which project outward of a portion at which the support frame is attached; and wire attaching sections which are connected to the elastic arm sections, respectively. A connecting position at which the wire attaching section and the elastic arm section are attached to each other is disposed outward of a fixing position where the leading end portion of a corresponding one of the support wires is fixed to the wire attaching section.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a U.S. national phase application under 35 U.S.C. §371 of International Patent Application No. PCT/JP2015/079762, filed Oct. 22, 2015, and claims benefit of priority to Japanese Patent Application No. 2014-242411, filed Nov. 28, 2014. The entire contents of these applications are hereby incorporated by reference. 
     
    
     FIELD OF TECHNOLOGY 
       [0002]    The present invention relates to a lens driving device. 
       BACKGROUND 
       [0003]    There is a known lens driving device provided with a driving portion of an electromagnetic driving type, made from a coil and the magnet. In this type of lens driving device, there is a driving device for the autofocus, which drives the lens frame along the optical axial direction, and a driving device for correcting camera shaking, which drives the lens frame in the directions that are perpendicular to the optical axis, where the camera that is disclosed in Japanese Unexamined Patent Application Publication No. 2011-65140, below, is provided with a combination of a driving device for autofocusing and a driving device for correcting camera shaking. 
         [0004]    In this type of lens driving device, a lens frame is attached to a supporting member through an elastic supporting member such as a leaf spring, or the like, and the position of the lens frame is controlled to the location of the equilibrium between the thrust that is produced by a driving portion and the elastic force of the elastic supporting member. The prior art set forth in Japanese Unexamined Patent Application Publication No. 2011-65140 is a camera shake correcting device for correcting camera shaking through moving the entirety of the autofocus lens driving device in the X and Y directions that are perpendicular to each other and perpendicular to the optical axis, comprising a base that is disposed separated from a bottom face portion of the autofocus lens driving device, and a plurality of wires (suspension wires) having one end each secured at an outer peripheral portion of the base, and that extend along the optical axis, to support the entirety of the autofocus lens driving device so as to swing in the X direction and the Y direction. 
       SUMMARY 
       [0005]    In the conventional lens driving device, the lens frame is supported elastically on a supporting member through a leaf spring, where end portions on one end of each wire are secured to the four corners of a leaf spring that is attached to the supporting member, with the other ends of the wires secured to a base supporting member. Because of this, the lens frame and the supporting member are supported in a state wherein they are suspended by the tip end portions of the wires. 
         [0006]    In such a lens driving device, when an external force, such as a dropping impact, or the like, is applied, the supporting member that is supported in a suspended state approaches the base supporting member side with a large acceleration, with the risk that a buckling load will act on a wire. When this is handled through increasing the rigidity of the wires, there will be a problem in that this is difficult in that if the driving portion is made smaller due to the need for miniaturization and weight reduction of the lens driving device, the thrust will be reduced. 
         [0007]    When the lens frame is moved in a direction that is perpendicular to the optical axis in order to correct camera shaking, the wires that elastically support the lens frame bend, of course, and at this time the lens frame cannot move in parallel to the optical axis, due to the rigidity of the wire that the location wherein the tip end portion and the leaf spring are secured, producing a problem in that the optical axis becomes tilted. This tilting of the optical axis produces a tilt to a degree in that the amount of movement in the direction that is perpendicular to the optical axis will be large. 
         [0008]    In the present invention, the handling of such problems is an example of the problem to be solved. That is, the problems to be solved by the present invention are those of preventing buckling and damaging of the wires when there is a dropping impact, and preventing tilting of the optical axis when correcting camera shaking, to enable high accuracy lens driving. 
         [0009]    In order to solve such a problem, the present invention is provided with the following structures: 
         [0010]    A lens driving device comprising: a lens frame; a supporting frame for supporting the lens frame elastically in the optical axial direction through a leaf spring; a base supporting member for supporting elastically the lens frame, which is supported on the supporting frame, in a direction that is perpendicular to the optical axis, through a supporting wire; and a driving portion for driving the lens frame in the optical axial direction and in one or both directions that are perpendicular to the optical axis, wherein: the leaf spring comprises an elastic arm portion that is pulled to the outside by an attaching portion of the supporting frame, and a wire attaching portion that is connected to the elastic arm portion; and the connecting position of the wire attaching portion and the elastic arm portion is disposed to the outside of a securing position for securing a tip end portion of the supporting wire to the wire attaching portion. 
         [0011]    The lens driving device according to the present invention, having such distinctive features, enables the prevention of buckling and damage to the wires at the time of a dropping impact, or the like, and enables highly accurate lens driving through preventing tilting of the optical axis when correcting camera shaking. 
     
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         [0012]      FIG. 1  is a cross-sectional diagram, when viewed from the optical axial direction, of a lens driving device according to an example according to the present invention. 
           [0013]      FIG. 2  is an overall perspective diagram of a lens driving device according to an example according to the present invention (in a state wherein the cover has been removed). 
           [0014]      FIG. 3  is a plan view of a lens driving device according to an example according to the present invention. 
           [0015]      FIG. 4A  is an overall plan view illustrating a front side leaf spring of a lens driving device according to an example according to the present invention. 
           [0016]      FIG. 4B  is a partial plan view illustrating a front side leaf spring of a lens driving device according to an example according to the present invention. 
           [0017]      FIG. 5A  is an explanatory diagram illustrating the deformed state of the front side leaf spring according to an example according the present invention. 
           [0018]      FIG. 5B  is an explanatory diagram illustrating the deformed state of the front side leaf spring according to an example according the prior art. 
           [0019]      FIG. 6  is a partial plan view illustrating the front side leaf spring of a lens driving device according to another example according to the present invention. 
           [0020]      FIG. 7A  is an explanatory diagram illustrating a camera equipped with the lens driving device according to examples according to the present invention. 
           [0021]      FIG. 7B  is an explanatory diagram illustrating a mobile information terminal equipped with the lens driving device according to examples according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    An embodiment according to the present invention will be explained below in reference to the drawings.  FIG. 1 through 3  illustrate the overall structure of a lens driving device according to an example according to the present invention. The lens driving device  1  includes a lens frame  2 , a supporting portion  3 , and a driving portion  4 . The lens frame  2  is equipped with a lens barrel attaching opening  2 S into which a lens barrel, not shown, is attached. The axis of the lens barrel attaching opening  2 S is the optical axis of the lens. In the below, the explanation will treat the object side of the lens as the “front,” and the image side of the lens as the “back.” In the figures, the optical axial direction is shown as the Z direction, and the directions that are perpendicular to the optical axis are shown as the X and Y directions. 
         [0023]    The driving portion  4  drives the lens frame  2  in the optical axial direction and in one or both of the directions that are perpendicular to the optical axis. The example in the figure illustrates an example that is provided with a driving portion for autofocusing, which drives in the optical axial direction, and a driving portion for camera shake correction, which drives the directions that are perpendicular to the optical axis. In the example in the figure, the driving portion  4  comprises a focusing coil  20  that is wound around the optical axis, on the outside surface of the lens frame  2 , four focusing magnets  21  that are disposed on the periphery of the lens frame  2 , two camera shake correcting magnets  23  ( 23 A and  23 B) wherein the directions of the magnetic fields are perpendicular in the X-Y directions, and respective camera shake correcting coils  22  ( 22 A and  22 B) that are disposed respectively therebehind. 
         [0024]    The supporting portion  3  elastically supports the lens frame  2  in the direction of driving of the driving portion  4 . The position of the lens frame  2  is controlled by the equilibrium of the thrust of the driving portion  4  and the elastic force of the supporting portion  3 . The supporting portion  3  is equipped with a supporting frame (a movable supporting frame)  10  that is disposed to the outside of the lens frame  2 , and a base supporting member  15  that is disposed to the rear of the lens frame  2 . The supporting frame  10  elastically supports, in the optical axial direction, the lens frame  2  through leaf springs (front side leaf springs  11  and  12  and back side leaf spring  13 ), and the base supporting member  15  elastically supports, in the directions that are perpendicular to the optical axis, the lens frame  2  that is supported on the supporting frame  10 , through a plurality of supporting wires  14 A,  14 B,  14 C, and  14 D, that are disposed along the optical axial direction. The supporting frame  10  is of a rectangular shape that surrounds the lens frame  2  around the optical axis, where the corner portions serve as magnet holding portions  10 P for holding the focusing magnets  21 , described above. 
         [0025]    Outer attaching portions  11 A and  11 B of the front side leaf spring  11  are attached to front end attaching portions  10 A and  10 B of the supporting frame  10 , and an inner attaching portion  11 C of the front side leaf spring  11  is attached to the front side attaching portion  2 A 1  that is attached to the front face  2 A of the lens frame  2 . Outer attaching portions  12 B and  12 A of the front side leaf spring  12  are attached to front end attaching portions  10 C and  10 D of the supporting frame  10 , and an inner attaching portion  12 C of the front side leaf spring  12  is attached to the front side attaching portion  2 A 1  that is provided on the front face  2 A of the lens frame  2 . 
         [0026]    In the front side leaf spring  11 , an elastic portion  11 D is provided between the outer attaching portions  11 A and  11 B and the inner attaching portion  11 C, and, similarly, in the front side leaf spring  12 , an elastic portion  12 D is provided between the outer attaching portions  12 A and  12 B, and the inner attaching portion  12 C. 
         [0027]    An outer attaching portion  13 A of the back side leaf spring  13  is attached to a back end attaching portion  10 E of the supporting frame  10 , and an inner attaching portion  13 B of the back side leaf spring  13  is attached to a back side attaching portion  2 C that is provided on the back face of the lens frame  2 . In the back side leaf spring  13 , an elastic portion  13 C is provided between the outer attaching portion  13 A and the inner attaching portion  13 B. 
         [0028]    The front side of the lens frame  2  is supported on the front side of the supporting frame  10  through the front side leaf springs  11  and  12 , which are provided with the elastic portions  11 D and  12 D, and the back side of the lens frame  2  is supported on the back side of the supporting frame  10  through the back side leaf spring  13  that is provided with the elastic portion  13 C. Through this, the lens frame  2  is supported elastically on the supporting frame  10  in regards to driving in the optical axial direction. 
         [0029]    The base supporting member  15  is disposed on the back side of the lens frame  2  and the supporting frame  10 , and is provided with a center opening portion  15 A through which light that has passed through a lens of a bottom plate  15 B passes. In the example in the figure, in the same manner as with the supporting frame  10 , the base supporting member  15  has a rectangular shape that has corner portions, around the optical axis, with wire holding portions  15 C provided in the corner portions. 
         [0030]    Supporting wires  14 A through  14 D have elasticity in relation to bending, with the back ends thereof held in wire holding portions  15 C of the base supporting member  15 , provided extending along the optical axis. Additionally, the tip end portions of the supporting wires  14 A through  14 D are secured to wire attaching portions  11 S and  12 S that protrude respectively to the outside from the outer attaching portions  11 A,  12 A,  11 B, and  12 B of the front side leaf springs  11  and  12  that are attached to the supporting frame  10 , where the supporting wires  14 A through  14 D support, in a suspended state, the supporting frame  10  that supports the lens frame  2  elastically. Through this, the lens frame  2  is supported elastically, relative to the driving directions that are perpendicular to the optical axis, through elastic bending of the supporting wires  14 A through  14 D. 
         [0031]    The base supporting member  15  is provided with an external connecting terminal  15 F, wherein a circuit for connecting the external connecting terminal  15 F is provided on the bottom plate  15 B, to structure a terminal portion for supplying power to the driving portion  4 . Portions of the external connecting terminal  15 F, which has a plurality of individual terminals, are connected to both ends of the camera shake correcting coils  22  ( 22 A and  22 B) that are supported in the coil supporting portion  15 D of the base supporting member  15  through the circuit that is provided on the bottom plate  15 B, to the terminals for supplying power to the camera shake correcting coils  22 . 
         [0032]    Other portions of the external connecting terminal  15 F are connected to both ends of the focusing coil  20  through the front side leaf springs  11  and  12  and the supporting wires  14 A and  14 B that are held in the wire holding portion  15 C, from the circuit that is provided on the bottom plate  15 B, to be a terminal for supplying power to the focusing coil  20 . 
         [0033]    Moreover, other portions of the external connecting terminal  15 F are connected to position detecting sensors  6  (or  6 A and  6 B) that are supported on a sensor supporting portion  15 E of the base supporting member  15 , through the circuit that is provided on the bottom plate  15 B, to the input/output terminals for the position detecting sensors  6  ( 6 A and  6 B). The position detecting sensors  6  ( 6 A and  6 B) may use Hall sensors (magnetism sensors), and magnets  7  ( 7 A and  7 B) for position detection are provided on the supporting frame  10  so as to face the position detecting sensors  6 . 
         [0034]    It is possible to carry out the independent focusing control and camera shake correcting control for the lens frame  2  by controlling the supplies of power to the focusing coil  20  and to the camera shake correcting coils  22  each independently. At this time, feedback control, using the detection signals from the position detecting sensors  6  ( 6 A and  6 B) is carried out in the camera shake correcting control. A filter frame (not shown), for example, is equipped behind the base supporting member  15 , and an imaging element is equipped behind that. Moreover, a cover  5  that is provided with a center opening  5 A is installed on the base supporting member  15  so as to encompass the outer periphery of the supporting frame  10 . 
         [0035]      FIG. 4  illustrates the front side leaf springs  11  and  12  (wherein (a) is an overall plan view and (b) is a partial plan view). The front side leaf springs  11  and  12  comprise elastic arm portions  11 T and  12 T that are pulled to the outside by attaching portions of the supporting frame  10 , where wire attaching portions  11 S and  12 S, and are connected respectively to the elastic arm portions  11 T and  12 T. The elastic arm portions  11 T and  12 T are provided in pairs on the left and right of the wire attaching portions  11 S and  12 S, and are connected at connecting positions R that are provided at two locations each. 
         [0036]    Given this, the connecting positions R of the wire attaching portions  11 S and  12 S and the elastic arm portions  11 T and  12 T are disposed to the outside of securing positions W wherein the tip end portions of the supporting wires  14 A through  14 D are secured to the wire attaching portions  11 S and  12 S. In the figure, the line L 1  is an imaginary line connecting a securing position W and the optical axis O, where the line L 2  is an imaginary line that passes through the securing position W, perpendicular to the line L 1 , and the connecting positions R, described above, are disposed to the outside of the line L 2  (on the side opposite from the optical axis side). 
         [0037]    Moreover, the elastic arm portions  11 T and  12 T and the wire attaching portions  11 S and  12 S are disposed at axially symmetrical positions around the optical axis O. In the example in the figure, the elastic arm portions  11 T and  12 T and the wire attaching portions  11 S and  12 S are disposed in four directions around the optical axis O. 
         [0038]    With the lens driving device  1  that is provided with such front side leaf springs  11  and  12 , as illustrated in  FIG. 5A , even when a large load acts on the supporting frame  10  in the direction of the arrow, an angular dislocation is produced between both portions of the connecting positions R between the wire attaching portions  11 S and  12 S and the elastic arm portions  11 T and  12 T, so that the wire attaching portions  11 S and  12 S that are supported by the supporting wires  14 A through  14 D will maintain the horizontal state. Through this, bending of the supporting wires  14 A through  14 D is suppressed extremely, making it possible to prevent buckling and damage of the supporting wires  14 A through  14 D in relation to dropping impacts, and the like. 
         [0039]    In contrast, in the leaf spring  11 J, such as in the prior art that is illustrated in  FIG. 5B , when the connecting positions R of the wire attaching portion  11 J 1  and the elastic arm portion  11 J 2  are arranged to the inside of the securing positions W, wherein the tip end portions of the supporting wires  14 A through  14 D are secured to the wire attaching portion  11 J 1 , the wire attaching portion  11 J 1  would be tilted by the dislocation of the supporting frame  10  in the direction of the arrow, which would produce a state wherein the supporting wires  14 A through  14 D tend to buckle, and are damaged easily through bending. 
         [0040]    Moreover, a lens driving device  1  according to an example according to the present invention is structured so that bending of the supporting wires  14 A through  14 D is unlikely in relation to movements of the supporting frame  10  (the lens frame  2 ), making it possible to suppress tilting of the optical axis of the lens frame  2 , even when the lens frame  2  is moved in a direction that is perpendicular to the optical axis through camera shake correction. This enables highly accurate lens driving. 
         [0041]      FIG. 6  illustrates another example configuration of the front side leaf springs  11  and  12 . Identical reference symbols are assigned to identical sites as in the example illustrated in  FIGS. 4A-4B , and redundant explanations are omitted. In this example, the point that the connecting positions R for the wire attaching portions  11 S ( 12 S) and the elastic arm portions  11 T ( 12 T) are arranged further out than the securing positions W for securing the tip end portions of the supporting wires  14 A through  14 D to the wire attaching portions  11 S ( 12 S) is the same as in the example illustrated in  FIG. 4B , but in contrast to the wire attaching portions  11 S ( 12 S) and the elastic arm portions  11 T ( 12 T) being connected at connecting positions R in two locations, in this example the wire attaching portion  11 S ( 12 S) and the elastic arm portion  11 T ( 12 T) are connected at a connecting position R at a single location. 
         [0042]    In the example illustrated in  FIG. 6 , the single connecting position R wherein the wire attaching portion  11 S ( 12 S) and the elastic arm portion  11 T ( 12 T) are connected is disposed to the outside relative to the line L 2  (the side that is opposite from the optical axial side) (where the line L 1  is an imaginary line that connects the securing position W and the optical axis O, and the line L 2  is an imaginary line that passes through the securing position W, perpendicular to the line L 1 ). The left and right elastic arm portions  11 T ( 12 T) are integrated together at the tip end parts thereof, and a single connecting position R is provided at the part wherein they are connected together. 
         [0043]    In the example illustrated in  FIG. 6 , the width of the connecting position R can be greater than the width of the tip ends of the elastic arm portions  11 T ( 12 T). The width of the tip ends of the elastic arm portion  11 T ( 12 T) must be set depending on the spring characteristics of the front side leaf spring  11  ( 12 ), and having the width of the connecting position R the greater than that relaxes the concentration of stresses at the connecting position R, enabling an increased connecting strength between the wire attaching portion  11 S ( 12 S) and the elastic arm portion  11 T ( 12 T) while preserving the desired spring characteristics. This enables improved durability of the front side leaf spring  11  ( 12 ). Moreover, through having the connecting position R be at a single location, this improves the component manufacturability of the front side leaf spring  11  ( 12 ). 
         [0044]    The lens driving device  1  that is equipped with the front side leaf springs  11  and  12  having the connecting positions R, as illustrated in  FIG. 6 , also, in the same manner as in the example described above, produces angular dislocation between both of the connecting positions R of the wire attaching portions  11 S and  12 S and the elastic arm portions  11 T and  12 T when a large load acts on the supporting frame  10  in the arrow direction, as illustrated in  FIG. 5A , so that the wire attaching portions  11 S and  12 S that are supported by the supporting wires  14 A through  14 D maintain the horizontal state. This can suppress extremely bending of the supporting wires  14 A through  14 D, enabling prevention of buckling and damage of the supporting wires  14 A through  14 D in respect to dropping impacts, and the like. 
         [0045]      FIG. 7  illustrates electronic devices equipped with lens driving devices  1  according to examples according to the present invention. The lens driving device  1  according to an example according to the present invention being mounted in a camera  100 , illustrated in  FIG. 7A , not only enables miniaturization, but enables high autofocusing performance and camera shake correcting performance. Moreover, installation in the mobile information terminal  200  (such as a mobile telephone, a smart phone, or the like), illustrated in  FIG. 7B , enables the device as a whole to be made thinner, and enables the camera function not part to have enhanced functionality with reduced space. 
         [0046]    While examples according to the present invention were described in detail above, referencing the drawings, the specific structures thereof are not limited to these examples, but rather design variations within a range that does not deviate from the spirit and intent of the present invention are also included in the present invention. Moreover, insofar as there are no particular contradictions or problems in purposes or structures, or the like, the technologies of the various examples described above may be used together in combination.