Patent Publication Number: US-2012039589-A1

Title: Image stabilization system

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to camera systems, and particularly to an image stabilization system. 
     2. Description of Related Art 
     In normal use of a camera, light rays from an object transmit into the camera and fall on a particular region of an image sensor. The image sensor forms an optical image associated with the object at a first position. 
     However, camera-shake is common during hand-held shooting. Consequently, light rays from the object may fall on a different region of the image sensor resulting in a blurry image. Current image stabilization systems that deal with this problem are expensive and complicated. 
     Therefore, a new image stabilization system is desired to overcome the above-mentioned problems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, all the views are schematic, and like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is an isometric view of an image stabilization system according to an exemplary embodiment. 
         FIG. 2  is an exploded, isometric view of the stabilizing system of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the stabilization system of  FIG. 1 , taken along a line III-III thereof. 
         FIG. 4  is a cross-sectional view of the stabilization system of  FIG. 1 , taken along a line IV-IV thereof. 
         FIG. 5  is a block diagram showing a relationship between a motion sensor, a control circuit, and a first magnetic driving unit of the stabilization system of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-5 , an image stabilization system  100 , in accordance with an exemplary embodiment, is shown. The system  100  includes a camera module  101 , a fixed body  110 , a movable frame  120 , a pivot member  150 , an elastic member  160 , a motion sensor  170 , a magnetic driving module  180 , and a magnetic shield unit  19  made of material having very high permeability to magnetic field. The camera module  101  has an optical axis O. 
     The fixed body  110  is substantially cubic. The fixed body  110  is securely mounted on a main body of an electronic device (not shown) using the system  100 . The fixed body  110  includes a main frame  111  and an attachable frame  112 . 
     The main frame  111  is substantially cubic, and includes a first sidewall  1111 , a second sidewall  1112 , a third sidewall  1113  opposite to the first sidewall  1111 , and a fourth sidewall  1114  opposite to the second sidewall  1112 . The first sidewall  1111  is parallel to the third sidewall  1113  and is perpendicular to the second sidewall  1112 . The second sidewall  1112  is parallel to the fourth sidewall  1114 . The four sidewalls  1111 ,  1112 ,  1113 , and  1114  cooperatively define a first receiving cavity  1115  for receiving the movable frame  120 . The first sidewall  1111  defines a first receiving hole  1116  at the center thereof. The second sidewall  1112  defines a second receiving hole  1117  at the center thereof. The third sidewall  1113  defines a third receiving hole  1118  at the center thereof. An upper end surface of the fourth sidewall  1114  defines a first receiving recess  1119  for receiving the attachable frame  112 . In other embodiments, the main frame  111  may instead be any other suitable shape, such as cylindrical, pentagonal prismatic etc. In this embodiment, an X axis is defined along a direction perpendicular to the first sidewall  1111 , and a Y axis is defined along a direction perpendicular to the second sidewall  1112  and a Z axis is defined along a direction parallel to a central line H of the main frame  111 . The Z axis is perpendicular to the X axis and the Y axis. 
     The attachable frame  112  is substantially L-shaped. The attachable frame  112  is configured for partially receiving the pivot member  150 , and conveniently fixing the elastic member  160  on the main frame  111 . The attachable frame  112  includes a plate  1121 , and a square frame  1122  perpendicular to the plate  1121 . The plate  1121  is securely mounted in the first receiving recess  1119 . The plate  1121  has an inner surface  1123  in the first receiving cavity  1115 . The inner surface  1123  defines a first receiving portion  1124  for partially receiving the pivot member  150  therein. The square frame  1122  is securely mounted on the top surfaces of the first, second, and third sidewalls  1111 ,  1112 , and  1113 . In the present embodiment, the first receiving portion  1124  is a round through hole having a diameter less than that of the pivot member  150 . In alternative embodiments, the first receiving portion  1124  may be a recess. In other alternative embodiments, the pivot member  150  may instead be partially received in the fourth sidewall  1114 . In such case, the recess  1119  and the plate  1121  may be omitted. 
     The movable frame  120  is substantially cubic, and is received in the first receiving cavity  1115 . The movable frame  120  is configured for securely receiving the camera module  101  therein. The movable frame  120  is substantially cubic, and includes a first outer surface  1211 , a second outer surface  1212 , a third outer surface  1213 , a fourth outer surface  1214 , and a top surface  1215 . The first outer surface  1211 , the second outer surface  1212 , the third outer surface  1213 , and the fourth outer surface  1214  are parallel to the optical axis O of the camera module  101 . The top surface  1215  is substantially perpendicular to the optical axis O of the camera module  101 . The top surface  1215  is substantially square, and is perpendicular to the four outer surfaces  1211 ,  1212 ,  1213 , and  1214 . The four outer surfaces  1211 ,  1212 ,  1213 , and  1214  and the top plate  1215  cooperatively define a second receiving cavity  1216  for securely receiving the camera module  101 . The first outer surface  1211  faces the first sidewall  1111 . The second outer surface  1212  faces the second sidewall  1112 . The third outer surface  1213  faces the third sidewall  1113 . The fourth outer surface  1214  faces the fourth sidewall  1114 . A central axis L of the movable frame  120  coincides with the optical axis O of the camera module  101 . When the system  100  stays still, the central axis H of the main frame  111  coincides with the optical axis O of the camera module  101  and the central axis L of the movable frame  120 . That is, when the system  100  stays still, the main frame  111  is coaxial to the movable frame  120  and the camera module  101 . 
     The top surface  1215  defines a through hole  1217  at the center thereof. The through hole  1217  allows light to pass through the top surface  1215  to reach the camera module  101 . In other embodiments, the movable frame  120  may instead be any other suitable shape, such as cylindrical, pentagonal prismatic etc. 
     The system  100  further includes a receiving member  122 . The receiving member  122  is configured for partially receiving the pivot member  150 , thereby engaging with the attachable frame  112  for receiving the pivot member  150 . In this embodiment, the receiving member  122  is securely mounted on the fourth outer surface  1214  and is spaced from the plate  1121 . The receiving member  122  has an outer surface  1221  facing the inner surface  1123 . The outer surface  1221  defines a second receiving portion  1222  for partially receiving the pivot member  150 . In the present embodiment, the second receiving portion  1222  is a recess. In other embodiments, the second receiving portion  1222  may be a round through hole. In a further embodiment, the receiving member  122  may be omitted. In such case, the pivot member  150  can be partially received in the fourth outer surface  1214  therein. 
     The camera module  101  is securely mounted in the movable frame  120 . The camera module  101  includes a lens module  130 , an image sensor  140  and a circuit board  141 . 
     The lens module  130  includes a first lens  131 , a second lens  132  and a barrel  133  receiving the first and second lenses  131 ,  132 . The lens module  130  has an optical axis coinciding with the optical axis O of the camera module  101 . In alternative embodiments, the camera module  101  may further include an actuator for moving the first lens  131  and/or the second lens  132  to achieve focusing and/or zooming of the camera module  101 . 
     The image sensor  140  is electrically connected and securely mounted to the circuit board  141 . The image sensor  140  is located at the image side of the lens module  130 . The circuit board  141  is securely mounted on the bottom end of the barrel  133 . The image sensor  140  is surrounded by the movable frame  120  in this embodiment. The image sensor  140  is configured for converting an optical image to an electrical signal. 
     The pivot member  150  is engagingly received in and between the first receiving portion  1124  and the second receiving portion  1222 , such that the movable frame  120  together with the camera module  101 , driven by the driving module  180 , can rotate around the pivot member  150  relative to the main frame  111 . In the present embodiment, the pivot member  150  is a rolling ball, and the movable frame  120  and the camera module  101  can rotate around both the X axis and Y axis. In other embodiments, the pivot member  150  may instead be a shaft, such that the movable frame  120  can only rotate around the X axis, or only rotate around the Y axis. 
     The elastic member  160  is configured for providing an elastic restoring force to make the movable frame  120  coaxial to the main frame  111 . The elastic member  160  is arranged between the main frame  111  and the attachable frame  112 . The elastic member  160  includes a first fixed portion  161 , a second fixed portion  162 , and an elastic connecting portion  163  connecting the first fixed portion  161  to the second fixed portion  162 . The first fixed portion  161  is, for example, adhesively mounted on the top surface  1215 . The second fixed portion  162  is securely mounted on the first sidewall  1111 , the second sidewall  1112 , and the third sidewall  1113 , thereby interposing the elastic connecting portion  163  between the fixed body  110  and the movable frame  120 . In alternative embodiments, the second fixed portion  162  may instead be secured on the square frame  1122 . In other alternative embodiments, the elastic member  160  may instead be a spring. In such case, the number of the elastic member  160  may be two, three, and so on. 
     The motion sensor  170  is securely mounted on the fourth outer surface  1214 , and is configured for sensing movement of the camera module  101  (i.e., movement of the movable frame  120 ). In such arrangement, the system  100  is compact. The motion sensor  170  can be a gyro sensor. 
     The driving module  180  is configured for driving the camera module  101  (i.e., the movable frame  120 ) to move relative to the main frame  111  to compensate for movements of the camera module  101  based on/associated with a motion detection result/signals of the motion sensor  170 , thereby eliminating/reducing blur due to camera shake. The driving module  180  includes a first magnetic driving unit  181 , a second magnetic driving unit  182 , and a control circuit  184 . The first magnetic driving unit  181  is arranged on the fixed body  110 . The second magnetic driving unit  182  is arranged on the first, second and third outer surfaces  1211 ,  1212 , and  1213 . The first magnetic driving unit  181  and the second magnetic driving unit  182  interact with each other to drive the movable frame  120  and the camera module  101  to rotate round the pivot member  150  relative to the fixed body  110 . 
     In this embodiment, the first magnetic driving unit  181  includes three electromagnetic members  1811 ,  1821 ,  1831  (e.g., coils, hereinafter a first electromagnetic member  1811 , a second electromagnetic member  1821  and a third electromagnetic member  1831 ). Each electromagnetic member is substantially a rectangular ring and includes an upper portion and a lower portion. For example, the first electromagnetic member  1811  includes an upper portion  1813  and a lower portion  1814 . The first electromagnetic member  1811  is received in the first through hole  1116 . The second electromagnetic member  1821  is received in the second through hole  1117 . The third electromagnetic member  1831  is received in the third through hole  1118 . 
     The second magnetic driving unit  182  includes three magnet units  1812 ,  1822 , and  1832  (hereinafter a first magnet unit  1812 , a second magnet unit  1822 , and a third magnet unit  1832 ). Each magnet unit is securely attached to a corresponding outer surface of the movable frame  120  and faces a corresponding electromagnetic member to interact with the corresponding electromagnetic member to generate a driving force. That is, the first magnet unit  1812  is positioned on the first outer surface  1211  and faces the first electromagnetic member  1811 . The second magnet unit  1822  is positioned on the second outer surface  1212  and faces the second electromagnetic member  1821 . The third magnet unit  1832  is positioned on the third outer surface  1213  and faces the third electromagnetic member  1831 . 
     Each magnet unit includes an upper magnet and a lower magnet. A magnetic pole of the upper magnet facing a corresponding electromagnetic member is opposite to a magnetic pole of the lower magnet facing the corresponding electromagnetic member. For example, the first magnet unit  1812  includes an upper magnet  1815  spatially corresponding to the upper portion  1813 , and a lower magnet  1816  spatially corresponding to the lower portion  1814 . A first magnetic pole  18  of the upper magnet  1815  facing the first electromagnetic member  1811  is opposite to a second magnetic pole  28  of the lower magnet  1816  facing the first electromagnetic member  1811 . In this embodiment, the first magnetic pole  18  is magnetic south, and the second magnetic pole  28  is magnetic north, as shown in  FIG. 2 . 
     The control circuit  184  is electrically connected to the first magnetic driving unit  181 . The control circuit  184  includes a processor  1841  and a driving circuit  1842  electrically connected to the processor  1841 . The processor  1841  is electrically connected to the motion sensor  170 . The driving circuit  1842  is electrically connected to the first electromagnetic member  1811 , the second electromagnetic member  1821  and the third electromagnetic member  1831 . The processor  1841  can be, for example, a digital signal processor (DSP) position controller. 
     The magnet shield unit  19  includes three U-shaped magnetic shields  190 ,  191 ,  192  (hereinafter a first magnetic shield  190 , a second magnetic shield  191 , and a third magnetic shield  192 ). 
     The first magnetic shield  190  is configured for enhancing magnetic fields of the first electromagnetic member  1811  and the first magnet unit  1812 , and preventing the magnetic fields from interfering with the normal operation of the camera module  101 , such as the image sensor  140 . In the present embodiment, the first magnetic shield  190  is made of ferronickel alloy. In alternative embodiments, the first magnetic shield  190  may instead be made of any other magnetically permeable material, such as electrically conductive polymer, surface conductive material, electrically conductive glass, etc. 
     The first magnetic shield  190  includes a first plate  1901 , a second plate  1902  opposite to the first plate  1901 , and a connecting plate  1903  perpendicularly connected the first plate  1901  and the second plate  1902 . The first plate  1901  is securely mounted on the movable frame  120 . The second plate  1902  is located on an opposite side of the first plate  1901  to the fixed body  110  such that the first electromagnetic member  1811  and the first magnet unit  1812  are arranged between the first plate  1901  and the second plate  1902 . In the present embodiment, the first plate  1901  is securely mounted on an inner surface of the movable frame  120 , and the second plate  1902  is away from an outer surface of the first sidewall  1111 . Thus, from the inside to the outside, the first plate  1901 , the first outer surface  1211 , the first magnet unit  1812 , the first electromagnetic member  1811 , and the second plate  1902  are arranged in that order. 
     The second magnetic shield  191  is similar to the first magnetic shield  190 , and is configured for enhancing magnetic fields of the second electromagnetic member  1821  and the second magnet unit  1822 , and preventing the magnetic fields from interfering with the normal operation of the camera module  101 . 
     The third magnetic shield  192  is similar to the first magnetic shield  190 , and is configured for enhancing magnetic fields of the third electromagnetic member  1831  and the third magnet unit  1832 , and preventing the magnetic fields from interfering with the normal operation of the camera module  101 . 
     In operation, at the beginning of capturing an image with the system  100 , the elastic members  160  are in a normal state and the movable frame  120  is coaxial to the main frame  111 ; and there is no power supplied to the first electromagnetic member  1811 , a second electromagnetic member  1821 , and the third electromagnetic member  1831 . At this moment, the system  100  forms an image associated with an object (not shown) on a first position of the image sensor  140 . 
     During image capture, camera shake may cause, for example, the system  100  to rotate clockwise around the Y axis relative to the object. Accordingly, the camera module  101  is rotated with the system  100 . The motion sensor  170  detects a movement of the camera module  101  and sends a motion detection result to the processor  1841 . Based on the motion detection result, the processor  1841  computes a compensating adjustment for the camera module  101  in order to reposition the image on the first position of the image sensor  140 . For example, the computed compensating angle may require the camera module  101  to rotate anti-clockwise around the Y axis a certain degree. The processor  1841  then sends a signal to the driving circuit  1842 , and the driving circuit  1842  applies power to the first electromagnetic member  1811  in response to the signal, such that the first magnet unit  1812  (i.e. the movable frame  120 ), is driven by magnetic force to rotate clockwise around the Y axis. 
     Hence, the movable frame  120  together with the camera module  101  is rotated anti-clockwise the predetermined angle around the Y axis, and the elastic connecting portion  163  becomes stretched. As a result, the system  100  forms an image associated with the object (not shown) on the first position of the image sensor  140  and camera shake is compensated for. In addition, the driving module  180  of the system  100  applies magnetic forces to drive the movable frame  120  to rotate around the pivot member  150 , and the control of the magnetic forces is easier. Therefore, the driving module  180  is simpler, and the system  100  is accordingly simpler, too. Therefore, the cost of the system  100  is lower. 
     After capturing the stabilized image of the object, even though the driving circuit  1842  may stop supplying power to the first electromagnetic member  1811 , the elastic restoring forces generated by the deformation of the elastic connecting portion  163  can drive the movable frame  120  to be coaxial to the main frame  111  again. 
     It is to be understood that when the system  10  shakes, the system  100  may be only rotated around the X axis. In such circumstances, the second electromagnetic member  1821  should and can be activated to adjust the position of the movable frame  120  and the camera module  101 . 
     It is also to be understood that when the system  10  shakes, the system  100  may be rotated around both the X axis and the Y axis. In these circumstances, the first electromagnetic member  1811 , a second electromagnetic member  1821 , and the third electromagnetic member  1831  may be activated to adjust a position of the movable frame  120  and the camera module  101 . 
     It is to be understood that in alternative embodiments, the first magnetic pole may be magnetic north, and the second magnetic pole may be magnetic south. The first magnetic driving unit  181  may include magnet units and the second magnetic driving unit  182  may include electromagnetic members. In such case, the control circuit  184  is electrically connected to the second magnetic driving unit  182 . 
     While certain embodiments have been described and exemplified above, various other embodiments will be apparent to those skilled in the art from the foregoing disclosure. The disclosure is not limited to the particular embodiments described and exemplified but is capable of considerable variation and modification without departure from the scope and spirit of the appended claims.