Abstract:
An image detecting module. The image detecting module comprises a base, a seat movably disposed on the base, an image detecting unit disposed on the seat, a first guide member by which the seat is joined to the base, moving relative to the base in a first direction, a first coil disposed on either the base or the seat, a first magnet disposed on either the base or the seat and opposite to the first coil, and a first Hall element disposed on either the base or the seat and adjacent to the first coil. A magnetic force is generated between the first coil and the first magnet by providing a voltage to the first coil, thereby moving the seat in the first direction along the first guide element.

Description:
BACKGROUND  
       [0001]     The invention relates to an image detecting module, and in particular to an image detecting module having an image detecting unit with 2-dimensional motion.  
         [0002]     Referring to FIG. 1, U.S. Pat. No. 5,266,988 discloses an image shake suppressing device for a camera. The image shake suppressing device is mounted in a lens. When the camera is used, an angular velocity meter measures the angular velocity of the moving camera and provides the measured data to a circuit to drive a driving part moving the lens in a direction of a vertical optical axis, thereby compensating or suppressing blurring due to vibration of the camera.  
         [0003]     Because the lens, however, is moved in a vertical optical axis, the MTF value thereof is reduced. This compensation method has limited compensation effect and may reduce image quality.  
         [0004]     Referring to FIGS. 2A and 2B, Japan patent No. 3551174 discloses a moving mechanism. The moving mechanism employs piezoelectric elements to drive an image detecting unit, such as CCD, in a vertical direction, such that blur can be compensated or suppressed, and it is applicable to any lens.  
         [0005]     The piezoelectric elements must be driven by voltage to move the CCD. As the CCD, however, is heavier than a single lens, a large piezoelectric element is needed, increasing the volume of the camera.  
       SUMMARY  
       [0006]     An embodiment of an image detecting module of the invention comprises a base, a seat movably disposed on the base, a image detecting unit disposed on the seat, a first guide member by which the seat is joined to the base and moves relative to the base in a first direction, a first coil disposed on either the base or the seat, a first magnet disposed on either the base or the seat and opposite the first coil, and a first Hall element disposed on either the base or the seat and adjacent to the first coil. A magnetic force is generated between the first coil and the first magnet by providing a voltage to the first coil, thereby moving the seat in the first direction along the first guide element.  
         [0007]     The first guide element comprises a plurality of first holding portions disposed on the base and the seat respectively, and a pair of first shafts held parallel by the first holding portions, whereby the seat is joined to the base, and the seat moves along the axis of the first shaft.  
         [0008]     The seat further comprises a movable plate movably disposed on the seat, and a circuit board joined to the movable plate, whereby the image detecting unit is electrically connected to the circuit board and fixed on the base.  
         [0009]     The image detecting module further comprises a second guide element by which the movable plate is joined to the seat and moves relative to the seat in a second direction, a second coil disposed on either the base or the movable plate, a second magnet disposed on either the base or the movable plate and opposite the second coil, and a second Hall element disposed on either the base or the movable plate and adjacent to the second coil. A magnetic force is generated between the second coil and the second magnet by providing a voltage to the second coil, thereby moving the seat along the second guide element in the second direction.  
         [0010]     The second guide element comprises a plurality of second holding portions disposed on the seat and the movable plate respectively, and a pair of second shafts held parallel by the second holding portions, whereby the movable plate is joined to the seat and moves along the axis of the second shaft.  
         [0011]     The axis of the second shaft is perpendicular to the axis of the first shaft.  
         [0012]     The first magnet comprises an N pole and an S pole disposed along the axis of the first shaft. The second magnet comprises an N pole and an S pole disposed along the axis of the second shaft.  
         [0013]     When the image detecting module is idle, two halves of the first Hall element are located on the N pole and the S pole of the first magnet respectively.  
         [0014]     When the image detecting module is idle, two halves of the second Hall element are located on the N pole and the S pole of the second magnet respectively. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:  
         [0016]      FIG. 1  depicts an image shake suppressing device disclosed in U.S. Pat. No. 5,266,988;  
         [0017]      FIGS. 2A and 2B  depict a moving mechanism disclosed in Japan Patent No. 3551174;  
         [0018]      FIG. 3  is a perspective view of an embodiment of an image detecting module of the invention;  
         [0019]      FIG. 4  is a rear view of a base of the image detecting module;  
         [0020]      FIG. 5  is a perspective view of a seat with a movable plate of the embodiment of the invention;  
         [0021]      FIG. 6  is a rear view of a seat with a movable plate of the embodiment of the invention; and  
         [0022]      FIG. 7  is a schematic view of a camera having the image detecting module of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0023]     Before the description, it is noted that location language, such as first direction X, second direction Y, or third direction Z, is based on the coordinate of each individual figure, and the first direction X, second direction Y, and the third direction Z are orthogonal.  
         [0024]     Referring to  FIG. 3 , an embodiment of an image detecting module of the invention comprises a base  20  with a hollow portion  29 , a seat  30  disposed in the hollow portion  29 , a movable plate  40  disposed in the seat  30 , and an image detecting unit  50  (such as a CCD)disposed on the movable plate  40 . The sensing surface of the image detecting unit  50  faces opposite the third direction Z.  
         [0025]     Referring to  FIG. 4 , the base  20  comprises a pair of first magnets  21  and  22 , a pair of second magnets  23  and  24  and a pair of parallel first shafts  25  and  26 . The first magnet  21  and  22  are disposed parallel on two sides of the hollow portion  29 . The N pole and S pole of the first magnet  21  are disposed along the first direction X, and the N pole and S pole of the first magnet  22  are also disposed along the first direction X. The second magnets  23  and  24  are disposed parallel on two sides of the hollow portions  29 . The N pole and the S pole of the second magnet  23  are disposed along the second direction Y, and the N pole and the S pole of the other second magnet  24  are also disposed along the second direction Y. In addition, N poles of the first magnet  21  and  22  face the hollow portion  29 , and the S poles of the second magnet  23  and  24  face the hollow portion  29 .  
         [0026]     Referring to  FIGS. 5 and 6 , the seat  30  has two wing portions  31   a  and  31   b . A pair of first coils  32   a  and  32   b  and a first Hall element  44   a  are disposed on the wing portions  31   a  and  31   b  respectively. The first coil  32   a  is disposed on the wing portion  31   a ; the first Hall element  44   a  is also disposed on the wing portion  31   a  and adjacent to the first coil  32   a ; the other first coil  32   b  is disposed on the wing portion  31   b . The first coils  32   a  and  32   b  are substantially rectangular and their longitudinal sides are parallel. The movable plate  40  also has two wing portions  41   a  and  41   b . A pair of second coils  42   a  and  42   b  and a second Hall element  44   b  are disposed on the wing portions  41   a  and  41   b  . The second coil  42   a  is disposed on the wing portion  41   a ; the second Hall element  44   b  is disposed on the wing portion  41   a  and adjacent to the second coil  42   a  ; the other second coil  42   b  is also disposed on the wing portion  41   b  . The second coils  42   a  and  42   b  are also substantially rectangular, and their longitudinal sides are parallel. Two first holding portions  35   a  and  35   b  are disposed on the seat  30  adjacent to the wing portion  41   a . The first holding portions  35   a  and  35   b  have holes  351   a  and  351   b  respectively; two first holding portions  35   c  and  35   d  are disposed on the seat  30  adjacent to another wing portion  41   b  . The first holding portion  35   c  and  35   d  has holes  351   c  and  351   d.    
         [0027]     A pair of first shafts  25  and  26  are parallel. The shorter first shaft  25  is disposed on the side of the magnets  21  and  24 , the longer first shaft  26  is disposed on the side of the magnet  23  away from the hollow portion  29 . The longer first shaft  26  extends through the holes  351   c  and  351   d  and is held by the first holding portions  35   c  and  35   d  and fixed to the holding portions  25   b  and  25   c . The shorter first shaft  25  extends through holes  351   a  and  351   b  and is fixed by the holding portion  25   a . The first shafts  25 ,  26  and the holding portions  25   a ,  25   b ,  25   c ,  35   a ,  35   b ,  35   c ,  35   d  constitute a first guide element  60 . The seat  30  moves in the first direction X via the first guide element  60 .  
         [0028]     Referring to  FIGS. 5 and 6 , the seat  30  has a hollow portion  39 . The image detecting unit  50  is disposed in the hollow portion  30  on the movable plate  40 . The movable plate  40  has a circuit board  45  to which the image detecting unit  50  is electrically connected. A rectangular frame  46  is fixed to the circuit board  45  and surrounds the image detecting unit  50 . A pair of parallel frame walls  461  and  462  of the rectangular frame  46  have second holding portions  463   a ,  463   b ,  463   c  and  463   d  respectively. The second holding portions  463   a ,  463   b ,  463   c  and  463   d  have holes  4631   a ,  4631   b ,  4631   c  and  4631   d  respectively. A pair of second shafts  47  and  48  are parallel to the second direction Y. The second shaft  47  extends through the holding portion  36   a  and  36   b  on the seat  30  and is inserted into holes  4631   a  and  4631   b  and fixed to the seat  30 . The other second shaft  48  extends through the holding portions  36   c  and  36   d  and holes  4631   c  and  4631   d , whereby the movable plate  40  is joined to the seat  30 . The second shafts  47 ,  48  and the holding portions  36   a ,  36   b ,  36   c ,  36   d ,  463   a ,  463   b ,  463   c , and  463   d  constitute a second guide element  70 . The movable plate  40  moves in the second direction Y via the second guide element  70 .  
         [0029]      FIG. 7  depicts a camera employing the image detecting unit of the invention. Referring to  FIGS. 3 and 7 , a camera  100  comprises a motion sensor  110 , such as an angular acceleration element or linear acceleration element. When the motion sensor  110  detects motion of the camera  100 , a PWM circuit  120  or a digital circuit provides a voltage signal to the first coils  32   a ,  32   b  and the second coils  42   a  and  42   b . The first coils  32   a ,  32   b  and the second coils  42   a ,  42   b  generate variable magnetic field interacting with the first magnet  21 ,  22  and the second magnet  23 ,  24 , whereby the seat  30  moves in the first direction X, the movable plate  40  moves in the second direction Y, and the image detecting unit  50  moves in the first direction X and the second direction Y correspondingly. Blurring is thereby modified or prevented.  
         [0030]     When the camera  100  is still, the image detecting module is also still. At this time, two halves of the first Hall element  44   a  are located on the N pole and the S pole of the first magnet  21 , and two halves of the second Hall element  44   b  are located on the N pole and the s pole of the second magnet  23 . The first and second Hall element  44   a  and  44   b  detect no magnetic field variation. When the camera  100  is moved, the first and second coils  42   a ,  42   b ,  43   a ,  43   b  interact with the first and second magnets  21 ,  22 ,  23  and  24  to move the seat  30  in the first direction X and the second direction Y. The Hall element  44   a  and  44   b  detects variation of the magnetic field to calculate the displacement and moving frequency of the seat  30 , whereby the voltage signal from the PWM circuit and the digital circuit is modified.  
         [0031]     Because the invention changes the position of the image detecting unit with respect to the optical axis rather than adjusting the lens position, image quality is affected. Further the pair of coils and a pair of magnets moving the image detecting unit resulting in the element having small volume, allowing reduced camera size.  
         [0032]     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.