Abstract:
The present invention relates to a moving member control apparatus that makes sure unerring control of a moving member having an ill-balanced structure and an imaging apparatus that incorporates that control apparatus.

Description:
The present application claims priority under 35 USC section 119 from Japanese patent application serial No. 2012-072763 filed in Japan on Mar. 28, 2012, the entire contents of which are hereby expressly incorporated by reference into the present application. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a moving member control apparatus that makes sure unerring control of a moving member having an ill-balanced structure and an imaging apparatus that incorporates that control apparatus. 
     There is a camera-shake correction apparatus as an example of controlling a moving member, and a conventional example of that camera-shake correction apparatus is typically shown in Patent Publication 1. This camera-shake correction apparatus includes a pair of voice coil motors in each of the X and Y directions of a moving member having an imaging device to make correction for camera-shake. The camera-shake correction apparatus disclosed in Patent Publication 1 comprises voice coil motors located in such a way as to apply force to the position of center of gravity of the moving member so that there is no rotation of the imaging device at the time of translation of the moving member in the X and Y directions. 
     Another example of the camera-shake correction apparatus is disclosed in Patent Publication 2. The camera-shake correction apparatus disclosed in Patent Publication 2 uses a spring that keeps a moving member against rotation upon application of force to it.
     Patent Publication 1: U.S. Pat. No. 4,564,930   Patent Publication 2: JP(A) 10-254019   

     SUMMARY OF THE INVENTION 
     Objects of the invention are to provide a small-size, high-degree-of-freedom-in-design moving member control apparatus capable of controlling a moving member in such a way as to move rapidly and unerringly, and an imaging apparatus incorporating the same. 
     The moving member control apparatus according to the present invention is characterized by comprising a base part, a moving part capable of moving relatively with respect to the base part, a first driving portion that applies driving force to the moving part, a second driving portion that applies driving force to the moving part, a first instruction portion that gives an instruction to the first driving portion about a displacement position (where to move), a second instruction portion that gives an instruction to the second driving portion about a displacement position, a first position acquisition portion that acquires a real position of the first driving portion, a second position acquisition portion that acquires a real position of the second driving portion, a first deviation calculation portion that calculates a first deviation between a displacement position given to the first instruction portion and a real position acquired by the first position acquisition portion, a second deviation calculation portion that calculates a second deviation between a displacement position given to the second instruction portion and a real position acquired by the second position acquisition portion, a correction portion that produces a first correction signal and a second correction signal corrected for the first deviation and the second deviation, respectively, depending on a difference between the first deviation and the second deviation, and a control portion that receives for the first correction signal and the second correction signal to control the driving forces of the first driving portion and the second driving portion, respectively. 
     Still other objects and advantages of the invention will in part be obvious and will in part be apparent form the specification. 
     The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is illustrative of the image-shake correction apparatus, before assembly, according to one embodiment of the invention. 
         FIG. 2  is illustrative of a base part. 
         FIG. 3  is illustrative of a moving part. 
         FIG. 4  is an illustration of  FIG. 3  as viewed from arrow A. 
         FIG. 5  is illustrative of a magnet support portion. 
         FIG. 6  is illustrative of the image-shake correction apparatus, after assembly, according to one embodiment of the invention. 
         FIG. 7  is an illustration of  FIG. 6  as viewed from arrow B. 
         FIG. 8  is illustrative of the operation of the image-shake correction apparatus, after assembly, according to one embodiment of the invention. 
         FIG. 9  is an enlarged view of a part of  FIG. 8 . 
         FIG. 10  is illustrative in schematic of the moving part of the image-shake correction apparatus according to one embodiment of the invention. 
         FIG. 11  is illustrative of what relations the Hall elements have to the center of gravity in one embodiment of the invention. 
         FIG. 12  is illustrative of the control block of the image-shake correction apparatus according to one embodiment of the invention. 
         FIG. 13  is a flowchart of the image-shake correction apparatus according to one embodiment of the invention. 
         FIG. 14  is illustrative of a specific imaging apparatus including the image-shake correction apparatus according to one embodiment of the invention. 
         FIG. 15  is illustrative of the image-shake correction apparatus, etc. in the imaging apparatus. 
         FIG. 16  is an enlarged view of the imaging apparatus in the vicinity of a tripod screw portion. 
         FIG. 17  is a block diagram of the control arrangement of the digital camera according to one embodiment of the invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     One embodiment of the invention will now be explained. 
       FIG. 1  is illustrative of an image-shake correction apparatus according of this embodiment of the invention before assembly. 
     The image-shake correction apparatus  1  according to the embodiment of the invention here serving as a moving member control apparatus comprises a base part  10  working as the foundation, a moving part  30  movably supported on the base part  10 , and a magnet support portion  50  that is opposed to the base part  10  with the moving part  30  between them and fixed to the base part  10 . 
     The base part  10  is fixedly provided with a first permanent magnet group  20 , and the magnet support portion  50  is fixedly provided with a second permanent magnet group  60 . The moving part  30  is fixedly provided with a coil group  40 . The first and second permanent magnet groups  20  and  60  include oppositely magnetized and located portions in such a way as to generate a magnetic field in an opposite space. The coil group  40  is located in a space where the first permanent magnet group  20  is opposite to the second permanent magnet group  60 . In  FIG. 1  and other figures, it is noted that the magnetic poles of the first and second permanent magnet groups  20  and  60  face on the side of the coil group  40 . 
       FIG. 2  is illustrative of the base part  10 . 
     The base part  10  comprises a base body  11  formed of a magnetic material such as iron or an iron alloy, supporting through-holes  12   a  and  12   b  that are provided through the base body  11  for inserting screws (not shown) through them to support the magnet support portion  50  on the base part  10 , and a first assembly of spring supports  13   a ,  13   b  and  13   c  for supporting springs (not shown) to support the moving part  30  on the base part  10  in a movable manner. 
     Here the X direction is defined as a first direction to the base part  10 , and the Y direction is defined as a second direction orthogonal to the X direction, as shown in  FIG. 2 . 
     The first permanent magnet group  20  on the base portion  10  comprises a first magnet portion  21  that is N-polarized on the coil group  40  side, a second magnet portion  22  that opposes to the first magnet portion  21  in the X direction and S-polarized on the coil group  40  side, a third magnet portion  23  that is located away from the first magnet portion  21  in the Y direction, a fourth magnet portion  24  that opposes to the third magnet portion  23  in the X direction and S-polarized on the coil group  40  side, and a firth magnet portion  25  that opposes to the fourth magnet portion  24  in the Y direction and N-polarized on the coil group  40  side. Note here that the faces of the first  21  to the fifth magnet portion  25  on the coil group  40  side and the opposite side are oppositely polarized. 
     The side of the second magnet portion  22  in the Y direction of the fourth magnet portion  24  is shorter than the first magnet portion  21  with a first space  101   a  leaving as a cutout that is not opposite to the first magnet portion  21 , and the side of the fourth magnet portion  24  in the Y direction of the second magnet portion  22  is shorter than the third magnet portion  23  with a second space  101   b  leaving as a cutout that is not opposite to the third magnet portion  23 . 
       FIG. 3  is illustrative of the moving part  30 , and  FIG. 4  is an illustration of  FIG. 3  as viewed from arrow A. 
     The moving part  30  comprises a moving body  31  formed of a nonmagnetic material such as an aluminum alloy or synthetic resin, a coil housing  32  provided on a part of the circumference of the moving body  31 , and a second assembly of spring supports  33   a ,  33   b  and  33   c  for supporting springs (not shown) to support the moving part  30  on the base part  10  in a movable manner. The moving part  30  is also provided with a Hall element assembly  34  and sensors like a temperature sensor  35 . The Hall element assembly  34  comprises a first Hall element  34   a , a second Hall element  34   b  and a third Hall element  34   c.    
     Here the X direction is defined as a first direction to the moving part  30 , and the Y direction is defined as a second direction orthogonal to the X direction, as shown in  FIG. 3 . 
     The moving body  31  includes an imaging device  36  for photoelectric conversion of light, a filter group  37  and an electric device  38  mounted on it. The filter group  37  comprises an ultrasonic filter  37   a  and an infrared cut filter  37   b  as viewed from its side away from the imaging device  36 . On the side of the filter group  37  opposite to the imaging device  36  there is the electric device  38  mounted to detect the quantity of light received at the imaging device and process image signals based on that quantity of light received, etc. 
     The coil housing  32  is provided on a part of the circumference of the moving body  31  and has a recess for stowing the coil group  40 . The moving body  31  is longer than the coil housing  32  in the Z direction orthogonal to the X and Y directions. 
     The coil group  40  comprises a first coil  41 , a second coil  42  and a third coil  43 . The first coil  41  is located in opposition to the first  21  and the second magnet portion  22  on the base part  10  shown in  FIG. 2 . The second coil  42  is located in such a way as to oppose to the third  23  and the fourth magnet portion  24  on the base part  10  shown in  FIG. 2 , and the third coil  43  is located in such a way as to oppose to the fourth  24  and the fifth magnet portion  25  on the base part  10  shown in  FIG. 2 . The first, second and third Hall elements  34   a ,  34   b  and  34   c  are mounted in such a way as to correspond to the first, second and third coils  41 ,  42  and  43 , respectively. 
       FIG. 5  is illustrative of the magnet support portion  50  of  FIG. 1 , as viewed from the moving part  30  side. 
     The magnet support portion  50  comprises a support body  51  formed of a magnetic material such as iron or an iron compound, and supporting through-holes  52   a  and  52   b  that are provided through the support body  51  for inserting screws (not shown) through it to support the magnet support portion  50  relative to the base body  10 . 
     Here the X direction is defined as a first direction to the magnet support portion  50 , and the Y direction is defined as a second direction orthogonal to the X direction, as shown in  FIG. 4 . 
     The second permanent magnet group  60  on the magnet support portion  50  comprises a first opposite magnet portion  61  that is S-magnetized on the coil group  40  side, a second opposite magnet portion  62  that is opposite to the first opposite magnet portion  61  and N-polarized on the coil group  40  side, a third opposite magnet portion  63  that is located away from the first opposite magnet portion  61  in the Y direction and S-polarized on the coil group  40  side, a fourth opposite magnet portion  64  that is opposite to the third opposite magnet portion  63  in the X direction and N-magnetized on the coil group  40  side, and a fifth opposite magnet portion  65  that is in opposition to the fourth magnet portion  64  in the Y direction and S-magnetized on the coil group  40  side. Note here that the first  61  to the fifth opposite magnet portion  65  are oppositely magnetized on the coil group  40  side and the opposite side. 
     The side of the fourth opposite magnet portion  64  in the Y direction of the second opposite magnet portion  62  has a cutout and is shorter than the first opposite magnet portion  61 , with a third space  102   a  serving as a cutout that is not in opposition to the first opposite magnet portion  61 , and the side of the second opposite magnet portion  62  in the Y direction of the fourth opposite magnet portion  64  has a cutout and is shorter than the third opposite magnet portion  63 , with a fourth space  102   b  serving as a cutout that is not in opposition to the third opposite magnet portion  63 . 
       FIG. 6  is illustrative of the image-shake correction apparatus  1  assembled according to the invention, and  FIG. 7  is an illustration of  FIG. 6  as viewed from arrow B. 
     To assemble the image-shake correction apparatus  1  according to the embodiment of the invention here, screws (not shown) are inserted through the supporting through-holes  12   a  and  12   b  in the base part  10  shown in  FIG. 1  and the threaded through-holes  52   a  and  52   b  in the magnet support portion  50 , and the support body  51  of the magnet support portion  50  is supported by a plate  41  attached to the base body  11  of the base part  10 . Consequently, the support body  51  is firmly supported on the base body  11  at three sites: supporting through-holes  12   a  and  12   b  and plate  14 . In addition, coil springs  15   a ,  15   b  and  15   c  are mounted on the first spring supports  13   a ,  13   b  and  13   c  of the base part  10 , and on the second spring supports  33   a ,  33   b  and  33   c  of the moving part  30 , respectively. 
     Preferably, the base part  10  and moving part  30  are supported in a fashion generally called the ball support wherein they are supported by a plurality of spherical balls (not shown) held between them. As the spherical balls roll, it enables the moving part  30  to move relative to the base part  10 . 
     With the image-shake correction apparatus assembled in place, the first permanent magnet group  20  of the base part  10  is opposite to, and away from, the second permanent magnet group  60  of the magnet support portion  50 . In a space between the first permanent magnet group  20  and second permanent magnet group  60 , there is a magnetic field generated because the magnets are oppositely magnetized. Then, the coil group  40  of the moving part  30  is located in a discrete space having the magnetic field generated in it. Such arrangement of the first permanent magnet group  20 , second permanent magnet group  60  and coil group  40  provides for formation of a voice coil motor  70 . 
     In the embodiment of the invention here, the first and second magnet portions  21  and  22 , first coil  41  and first and second opposite magnet portions  61  and  62  are combined together into a first X-direction voice coil motor  71  operating as a first voice coil motor for moving the moving part  30  in the X direction defined as the first direction, and the third and fourth magnet portions  23  and  24 , second coil  42  and third and fourth opposite magnet portions  63  and  64  are combined together into a second X-direction voice coil motor  72  operating as a second voice coil motor for moving the moving part  30  in the X direction defined as the first direction. Further, the fourth and fifth magnet portions  24  and  25 , third coil  43  and fourth and fifth opposite magnet portions  64  and  65  are combined together into a Y-direction voice coil motor  73  operating as a third voice coil motor for moving the moving part  30  in the Y direction defined as the second direction. 
     Consequently, the fourth magnet portion  24  and the fourth opposite magnet portion  64  will be included in both the second X-direction voice coil motor  72  and Y-direction voice coil motor  73 . Thus, at least one magnet portion in the first and second magnet groups  20  and  21  is set up in such a way as to be included in both the X- and Y-direction voice coil motors  72  and  73  to have a dual function of moving the moving part  30  in the X and Y directions. This will contribute to a reduction of parts count, and make it possible to reduce the size and cost of the apparatus. 
     In the embodiment of the invention here, as an electric current flows through the first and second coils  41  and  42 , it causes the moving part  30  to move in the X direction, and as an electric current flows through the third coil  43 , it causes movement of the moving part  30  in the Y direction. 
     In the embodiment of the invention here, the first and second magnet portions  21  and  22  in the first permanent magnet group  20  are magnetized as a single magnet; the third, fourth and fifth magnet portions  23 ,  24  and  25  in the first permanent magnet group  20  are magnetized as a single magnet; the first and second opposite magnet portions  61  and  62  in the second permanent magnet group  60  are magnetized as a single magnet; and the third, fourth and fifth opposite magnet portions  63 ,  64  and  64  in the second permanent magnet group  60  are magnetized as a single magnet. However, they may be magnetized as separate magnets or, alternatively, some of them may be magnetized as a separate magnet. Such separate magnetization could facilitate processing, and allow for simple low-cost production. The number of turns of the first, second and third coils  41 ,  42  and  43  may be varied depending on the volume of the cutout. 
     It is here to be noted that how to fix each magnet to the base part  10  and magnet support portion  50  is not specifically limited: it may be fixed using screwing, caulking or the like. In the embodiment of the invention here, an adhesive is typically used to fix the magnet to the base part  10  and magnet support portion  50 . 
       FIG. 8  is illustrative of the operation of the image-shake correction apparatus  1  after assembled according to the embodiment of the invention here, and  FIG. 9  is an enlarged view of a part of  FIG. 8 . It is here to be noted that the magnet support portion  50  is left out of  FIG. 8  for the purpose of making movement of the moving part  30  more visible, and only the first and second magnet portions  21  and  22  are shown together with the moving body  31  in  FIG. 9 . 
     As shown typically in  FIG. 8 , suppose now that the moving part  30  moves relative to the base part  10  in a direction indicated by arrow C. Thereupon, the moving body  31  comes closer to the first and second magnet portions  21  and  22 . If the Y-direction length of the second magnet portion  22  is the same as the Y-direction length of the first magnet portion  21 , then the moving body  31  will interfere with the magnet portion  22 . 
     With the first space  101   a  defined by a cutout formed by making the Y-direction length of the second magnet portion  22  shorter than the Y-direction length of the first magnet portion  21 , it is then possible to avoid interference of the moving body  31  with the second magnet portion  22 , thereby reducing the size of the apparatus. It is here to be noted that if the first and second spaces  101   a  and  101   b  serving as cutouts are positioned in the central direction side of the base part  10  or moving part  30 , the apparatus could be further reduced in size, or if the cutouts are positioned in a position where they overlap at least a part of a range wherein the moving part  30  is movable by the voice coil motor  30 , the apparatus could be even further reduced in size. 
     It is here to be noted that if a cutout is provided for other magnet portion too, it is then possible to avoid interference of the moving body  31  with that magnet portion or interference of that magnet portion with other member, thereby reducing the size of the apparatus without narrowing down the moving range of the moving part  30 . 
     While the embodiment of the invention here is explained with reference to a specific arrangement having permanent magnet groups in both the base part  10  and the magnet support portion  50 , it is to be understood that only one of them may include permanent magnet groups provided that there is an output capable of moving the moving part  30 . 
     Reference will now be made to control of the moving part in the image-shake correction apparatus  1  according to the embodiment of the invention here. 
       FIG. 10  is illustrative in schematic of the moving part  30  of the image-shake correction apparatus  1  according to the embodiment of the invention here. 
     The operation of the image-shake correction apparatus  1  according to the embodiment of the invention here is now explained with reference to  FIG. 10 . As shown, the first X-direction voice coil motor  71  as a first driving or actuating member and the second X-direction voice coil motor  72  as a second driving or actuating member are actuated to apply force to the moving part  30  thereby moving it in the X direction, and the Y-direction voice coil motor  73  as a third driving or actuating member is actuated to apply force to the moving part  30  thereby moving it in the Y direction. It is here to be noted that not only the voice coil motors but also other actuators capable of generating driving force may be used as the first, second and third actuating members. 
     For instance, while the first and second X-direction voice coil motors  71  and  72  are driven in place, the Y-direction voice coil motor  73  is actuated by an instruction given to it about the amount of driving thereby parallel shifting the moving part  30  in the Y direction, and while the Y-direction voice coil motor  73  is driven in place, the first and second X-direction voice coil motors  71  and  72  are actuated as much by an instruction given to them thereby parallel shifting the moving part  30  in the X direction. Further, as different amounts of driving are given to the first and second X-direction voice coils  71  and  72  and the Y-direction voice coil motor  73  for their actuation, it causes rotation of the moving part  30 . 
     It is here to be noted that the voice coil motors  71 ,  72  and  73  are each provided with a Hall element  34  serving as a corresponding position acquisition element in the vicinity of the corresponding moving part  30  so that the positions of the voice coil motors  71 ,  72  and  73 , for instance, the positions of movement of the first, second and third coils  41 ,  42  and  43  in a normal state can be detected. 
       FIG. 11  is illustrative of relations between the Hall elements here and the center of gravity. 
     In the embodiment of the invention here, Hall elements  34  and the center of gravity G are located in such a way as to meet the relations shown in  FIG. 11 . As shown in  FIG. 10 , the moving part  30  receives driving forces from the voice coil motors  71 ,  72  and  73 . For instance, when, as contemplated herein, the position of center of gravity G of the moving part  30  does not lie on the straight line of the vector of the driving or actuating force given by the Y-direction voice coil motor  73  to the moving part  30  and the driving force acts in a direction different from the position of center of gravity G of the moving part  30 , not only the translational force in the Y direction but also torque about the center of gravity and translational force in the X direction occur upon application of force to the moving part  30 . The torque and translational force in the X direction are unnecessary force components, and they may be diminished by simple feedback control of the first and second X-direction voice coil motors  71  and  72 . However, the torque and translational force in the X direction constantly remain disturbing factors for the first and second X-direction voice coil motors  71  and  72 , which may otherwise lead to a lowering accuracy of position control performance. 
     In the embodiment of the invention here, therefore, the voice coil motors  71 ,  72  and  73  are each controlled in such a way as to achieve a further reduction of torque and translational force occurring upon application of force to the moving part  30  by the voice coil motors  71 ,  72  and  73 . 
     It is here to be noted that if the voice coil motors  71 ,  72  and  73  are each set up in such a way as to apply driving force to the moving part  30  in a direction different from the center of gravity G, it is then possible to achieve small-format size and bring up the degree of freedom in design, and so make contributions to size reductions. In addition, if at least two voice coil motors are designed to apply driving forces in parallel, it is then possible to achieve fast operation of the precise position of the moving part  30  and reduce to an amount of processing steps on that control operation. 
       FIG. 12  is a control block diagram for the image-shake correction apparatus  1  according to the embodiment of the invention here. 
     The control block of the image-shake correction apparatus  1  comprises a correction portion  2 , a control portion  3  and a voice coil motor  70 . 
     First, a first target displacement position signal r X1  indicative of a displacement position is entered from a first instruction portion  4 A into a first X-direction voice coil motor  71 , whereupon a first X-direction deviation e X1  serving as a first deviation that is a difference between the first target displacement position signal r X1  and the present position X 1   pos  of the second X-direction voice coil motor  72  is calculated out at a first deviation calculation portion  5 A, providing feedback control. 
     Likewise, a second target displacement position signal r X2  indicative of a displacement position is entered from a second instruction portion  4 B into a second X-direction voice coil motor  72 , whereupon a second X-direction deviation e X2  serving as a second deviation that is a difference between the second target displacement position signal r X2  and the present position X 2   pos  of the second X-direction voice coil motor  72  is calculated out at a second deviation calculation portion  5 B, providing feedback control. 
     Further, a third target displacement position signal r y  indicative of a displacement position is entered from a third instruction portion  4 C into a Y-direction voice coil motor  73 , whereupon a Y-direction deviation e y  serving as a third deviation that is a difference between the third target displacement position signal r y  and the present position Y pos  of the Y-direction voice coil motor  73  is calculated out at a third deviation calculation portion  5 C, providing feedback control. 
     The correction portion  2  receives the first X-direction deviation e X1  and adds up a value obtained by multiplying a difference between the first deviation and the second deviation by a first correction coefficient Rk X1 , producing an output as a first correction output signal r′ x1 , and the correction portion  2  also receives the second X-direction deviation e X2  and adds up a value obtained by multiplying a difference between the first deviation and the second deviation by a second correction coefficient Rk X2 , producing an output as a second correction output signal r′ X2 . Further, the correction portion  2  receives the Y-direction deviation e y  and adds up a value obtained by multiplying a difference between the first deviation and the second deviation by a third correction coefficient Rk y , producing an output as a third correction output signal r′ y . 
     The control portion  3  receives the first correction output signal r′ X1  and implements phase compensation/gain multiplication processing or the like with a first X-direction IIR filter or the like, producing a first X-direction filter output I X1 . The control portion  3  also receives the second correction output signal r′ X2  and implements phase compensation/gain multiplication processing or the like with a second X-direction IIR filter or the like, producing a second X-direction filter output I X2 . Further, the control portion  3  receives the third correction output signal r′ y  and implements phase compensation/gain multiplication processing or the like with a Y-direction IIR filter or the like, producing a Y-direction filter output I y . 
     The voice coil motor  70  drives the first X-direction voice coil motor  71  (P X1 ) by a first X-direction output I X1  from the control portion  3 . The voice coil motor  70  also drives the second X-direction voice coil motor  72  (P X2 ) by a second X-direction output I X2  from the correction portion  2 . Further, the voice coil motor  70  drives the Y-direction voice coil motor  73  (P y ) by a Y-direction output I y  from the correction portion  2 . 
     How to calculate the first, second and third correction coefficients Rk X1 , Rk X2  and Rk y  multiplied in the correction portion  2  is now explained. 
     In the arrangement of the Hall elements  34  shown in  FIG. 11 , suppose that R X1  is indicative of a distance from the position of center of gravity to the first Hall element  34   a , R X2  is indicative of a distance from the position of center of gravity to the second Hall element  34   b , and Ry is indicative of a distance from the position of center of gravity to the third Hall element  34   c . Then, movements ΔH X1 , ΔH X2  and ΔH y  of the first, second and third Hall elements  34   a ,  34   b  and  34   c  from the reference point of a rotation system could be given by the following Expressions (1), (2) and (3).
 
Δ H   X1   =R   X1  sin(θ X1 −θrot)− R   X1  sin(θ X1 )  (1)
 
Δ H   X2   =R   X2  sin(θ X2 +θrot)− R   X2  sin(θ X2 )  (2)
 
Δ H   y   =R   y  sin(θ y +θrot)− R   X2  sin(θ y )  (3)
 
     Here, Expressions (1), (2) and (3) could be transformed into the following Expressions (4), (5) and (6) by approximation to a trigonometric function with the proviso of θrot=(−ΔH X1 +ΔH X2 )/(R X1 +R X2 ).
 
Δ H   X1   =−R   X1 ×(−Δ H   X1   +ΔH   X2 )  (4)
 
Δ H   X2   =R   X2 ×(−Δ H   X1   +ΔH   X2 )/( R   X1   +R   X2 )  (5)
 
Δ H   y   =R   y ×(−Δ H   X1   +ΔH   X2 )/( R   X1   +R   X2 )  (6)
 
     Therefore, the first, second and third correction coefficients Rk X1 , Rk X2  and Rk y  could become the following Expressions (7), (8) and (9).
 
 Rk   X1   =−R   X1 /( R   X1   +R   X2 )  (7)
 
 Rk   X2   =R   X2 /( R   X1   +R   X2 )  (8)
 
 Rk   y   =R   y /( R   X1   +R   X2 )  (9)
 
     Thus, by correcting the signals sent out to the first X-direction voice coil motor  71 , second X-direction voice coil motor  72  and Y-direction voice coil motor  73  with the first, second and third correction coefficients Rk X1 , Rk X2  and Rk y , respectively, it is possible to prevent the moving part  30  from unnecessary rotation and process it constantly in an unerring position. 
       FIG. 13  is a flowchart of the image-shake correction apparatus  1  according to the embodiment of the invention here. 
     For control of the moving member of the image-shake correction apparatus  1  according to the embodiment of the invention here, target drive positions X, Y and θ are first acquired in Step  1  (ST 1 ). 
     Then, the process goes to Step  2  for transforming the target drive positions X, Y and θ into the amounts of translational driving r X1 , r X2  and r y  in the respective X 1 , X 2  and Y axis directions (ST 2 ). 
     Then, the process goes to Step  3  for acquiring the present positions X 1   POS , X 2   POS  and Y POS  by the first, second and third Hall elements  34   a ,  34   b  and  34   c , respectively (ST 3 ). 
     Then, the process goes to Step  4  for finding differences of the present positions X 1   POS , X 2   POS  and Y POS  of the respective axes, obtained in Step  3 , from the amounts of translational driving in the respective axis directions, obtained in Step  2 , thereby calculating the deviations e y , e X1  and e X2  of the respective axes (ST 4 ). 
     Then, the process goes to Step  5  for calculating a deviation difference (e X2 −e X1 ) in the X 1  and X 2  directions in the correction portion  2  (ST 5 ). 
     Then, the process goes to Step  6  where, in the correction portion  2 , a first correction value Rk X1 (e X2 −e X1 ) obtained by multiplying the X 1 - and X 2 -direction deviation difference (e X2 −e X1 ) by the first correction coefficient Rk X1  and the first X-direction deviation e X1  are added up into a first X-direction correction output r X1 , a second correction value Rk X2 (e X2 −e X1 ) obtained by multiplying the X 1 - and X 2 -direction deviation difference (e X2 −e X1 ) by the second correction coefficient Rk X2  and the second X-direction deviation e X2  are added up into a second X-direction correction output r X2 , and a third correction value Rk y (e X2 −e X1 ) obtained by multiplying the X 1 - and X 2 -direction deviation difference (e X2 −e X1 ) by the third correction coefficient Rk y  and the Y-direction deviation e y  are added up into a Y-direction correction output r y  (ST 6 ). 
     Then, the process goes to Step  7  for calculation of control filter outputs I X1 , I X2  and I y  of the respective axes in the control portion  3  (ST 7 ). 
     Then, the process goes to Step  8  for driving the voice coil motors of the respective axes depending on the results of calculation (ST 8 ). 
     Such moving member control allows for a small-format apparatus having a high degree of freedom in design, and enables control of the moving part  30  such that it moves rapidly and unerringly relative to the base part  10 . 
     The image-shake correction apparatus as described above may be used with electronic imaging apparatus, inter alia a digital camera, a video camera or the like, as can been seen from the following exemplary embodiments. 
       FIG. 14  is illustrative of an imaging apparatus comprising the image-shake correction apparatus according to one embodiment of the invention, and  FIG. 15  is illustrative of the image-shake correction apparatus, etc. within the imaging apparatus. 
     A digital camera  80  that is an imaging apparatus comprising the image-shake correction apparatus according to one embodiment of the invention comprises a camera body  81 , and a lens unit  82  including an imaging lens L that is interchangeably mounted on the camera body  81 , as shown in  FIGS. 14 and 15 . 
     It is here to be noted that an axis of light entering from the imaging lens L into the camera body  81  is indicated by O, and that the object side of the cameral body  81  with respect to the axis of incident light is called the front (front surface side) and the imaging side is called the rear (rear surface side). It is also to be noted that of directions orthogonal to the optical axis O, the horizontal direction as viewed from the front in an ordinary operation state is defined as the first or X direction, and the vertical direction is defined as the second or Y direction. The first or X direction and the second or Y direction correspond to the first or X direction and the second or Y direction with respect to the image-shake correction apparatus  1 . 
     The camera body  81  comprises an outer casing  83  also serving as a camera proper that houses therein members forming the digital camera  80 , and includes in a front position on the incident optical axis O a ring-like mount  84  for interchangeable mounting of the lens unit  82 . On the left side as viewed from the front, the outer casing  83  is provided with a grip (not shown) held by the right hand of a camera operator during imaging operation. On top of the grip there are various switches and buttons such as a release button located. 
     Further, the camera body  81  comprises a battery chamber  92  for stowing away batteries  91  within the outer casing  83 . In the rear of the battery chamber  92 , there are a circuit board or the like (not shown) provided, having a circuit board or the like (not shown) including a control circuit for implementing control over the camera, image processing, compression processing, data storage processing or the like, and a memory such as SDRAM and a power source circuit, etc. Furthermore, the camera body  81  has a built-in shake-status detector (not shown) for that camera body which uses a gyro sensor or the like as an example. 
     As shown in  FIGS. 14 and 15 , the camera body  81  further comprises a liquid crystal panel  86  having a panel display window on the rear surface side of the outer casing  83 . This liquid crystal panel  86  is a TFT (thin-film transistor) type of rectangular display panel that is capable of not only displaying taken images but also showing as images various information pieces such as various settings and adjustments. On top of the outer casing  83 , there is a hot shoe  87  located for attachment of an optical viewfinder, an electronic viewfinder, an external flash, a microphone, etc. 
     Within the outer casing  83  of the camera body  81 , there are a focal plane shutter  88  and an imaging unit  89  received as shown in  FIG. 14 . The imaging unit  89  comprises an image-shake preventing apparatus  1  that supports an imaging device  36  such as a CCD (charge coupled device (image sensor)) and a CMOS sensor (complementary metal oxide semiconductor (image sensor)) on the XY plane in a displaceable fashion and uses a voice coil motor as an actuator. This image-shake preventing apparatus  1  operates in response to a shake signal from the above-mentioned shake detector to cancel out the force detected in the shake direction. The imaging device  36  includes a light-receiving plane having a long side along the X direction. The outer casing  83  is provided on its bottom surface with a tripod screw portion  90 . 
       FIG. 16  is an enlarged view of the digital camera  80  in the vicinity of the tripod screw portion. 
     Upon mounting of the image-shake correction apparatus  1  to the digital camera  80 , there is a possibility that it may interfere with the tripod screw portion  90 . Such interference can be avoided if the X-direction lengths of the fourth and fifth magnet portions  64  and  65  are made different from each other to receive the tripod screw portion  90  in the fifth space  103   a  as shown in  FIG. 16 . 
     Thus, upon attachment of the image-shake correction apparatus  1  to the digital camera  80 , there is a possibility that the members within the digital camera  80  may interfere with the image-shake correction apparatus  1 . This interference of the members within the digital camera  80  with the image-shake correction apparatus  1  can be avoided if the lengths of the magnet portions are made different from each other to form a cutout for receiving those members, thereby reducing the size of the digital camera  80 . 
       FIG. 17  is a block diagram illustrative of the internal circuitry of a main part of the digital camera  80  according to the embodiment of the invention here. In the following explanation, the processing means are constructed typically from a CDS/ADC portion  124 , a temporal storage memory  117 , an image processing portion  118  and so on, and the storage means are made up of a storage medium and so on. 
     As shown in  FIG. 17 , the digital camera  80  includes an operating portion  112 , a control portion  113  connected to the operating portion  112 , an imaging drive circuit  116  and a temporal storage memory  117  connected to the control signal output port of the control portion  113  via buses  114  and  115 , an image processing portion  118 , a storage medium portion  119 , a display portion  120 , and a preset information storage memory portion  121 . 
     The temporal storage memory  117 , image processing portion  118 , storage medium portion  119 , display portion  120  and preset information storage memory portion  121  are designed such that data are mutually entered in or produced out of them via a bus  22 , and the imaging drive circuit  116  is connected with the imaging device  36  and CDS/ADC portion  124 . 
     The operating portion  112  is a circuit including various input buttons and switches, through which event information entered (by the camera operator) from outside is notified to the control portion  113 . The control portion  113  is a central processing unit that is made up of typically a CPU and has a built-in program memory (not shown): it is a circuit that, according to the program loaded in that program memory, has control over the digital camera  80 . 
     The imaging device  36  such as the CCD is the one that is driven and controlled by the imaging drive circuit  116 , and converts or transforms light quantity per pixel of the object image formed through the imaging optical system  111  into electrical signals that are in turn sent out to the CDS/ADC portion  24 . 
     The CDS/ADC portion  124  is made up of a co-related double sampling circuit and an analog to digital conversion circuit, and amplifies electrical signals entered from the imaging device  36  to remove noises from the electrical signals from the imaging device  36  by means of co-related double sampling. Then, the electrical signals cleared of noises are subjected to analog to digital conversion so that image raw data (Bayer pattern output image data: hereinafter called the RAW data) subjected only to amplification and digital conversion are sent out to the temporal storage memory  117 . 
     The temporal storage memory  117  is a buffer memory made up of typically an SDRAM (synchronous dynamic random access memory): it is a memory device for temporal storage of the RAW data produced out of the CDS/ADC portion  124 . The image processing portion  118  is a circuit that reads out the RAW data stored in the temporal storage memory  117  or the RAW data stored in the storage medium portion  119  thereby electrically implementing various forms of processing including distortion correction, based on an image quality parameter instructed by the control portion  113 . 
     The storage medium portion  119  detachably receives a card type or stick type of recording medium comprising typically a flash memory so that the RAW data transferred from the temporal memory  117  or image data processed at the image processing portion  118  are recorded and held in that flash memory  117 . 
     The display portion  120  is made up of a liquid crystal display monitor or the like to display the taken RAW data or image data, operating menus or the like on it. The preset information storage memory portion  121  includes a ROM (read only memory) portion having various image quality parameters previously loaded in it, and a RAM (random access memory) portion for storing an image quality parameter read out of that ROM portion by entering operation of the operating portion  112 . 
     The thus setup digital camera  80  makes use of the inventive lens system as the imaging optical system  114 , providing an imaging apparatus that is of small-format size and well fit for taking of moving images. 
     It is to be understood that some embodiments described herein are not intended as limitations on the present invention. Although many exemplary specific details are included in the explanation of illustrative embodiments, it will be readily apparent to those skilled in the art that varying substitutions or modifications may be made to such detailed disclosures without departing from the scope of the invention. In other words, some exemplary embodiments of the invention have been described without losing the generality of the invention recited in the claims, and imposing any particular limitations on the invention. 
     For instance, some exemplary embodiments of invention have been explained with reference to a structure capable of moving and controlling the moving part  30  including the imaging device  36 ; however, the invention may also be applied to an arrangement having the lens unit  82  as the moving part to be controlled. Alternatively, the invention illustratively described herein may also be applied to a translational moving member such as a printer s head.