Abstract:
An exemplary camera module includes a fixture, a lens module, a movable frame, an image sensor, a position sensor, a first and a second magnet, and a first and a second magnetic field generator. The position sensor is used to detect displacements of the lens module caused by shake. The magnetic field generators are used to apply a magnetic field to the corresponding magnets, each of the magnetic field generators is electrifiable in response to detection by the position sensor of displacement of the lens module caused by shake. Accordingly, at least one of the magnets and the corresponding magnetic field generator cooperatively drive the lens module to move and compensate the displacement of the image sensor.

Description:
BACKGROUND 
     1. Technical Field 
     The disclosure generally relates to camera modules, and particularly, to an anti-shake camera module. 
     2. Description of Related Art 
     Lens modules and image sensors are key components of camera modules. Generally, light beams from an object transmit through the lens module along a predetermined path and fall on a central region of the image sensor. When an image plane of the object is precisely on the image sensor, a clear image is obtained. However, camera shake occurring at the time of image capture causes either or both of the lens module and the image sensor to move slightly relative to the object. Due to resultant imprecision between image plane of the object and the image sensor, blurred image is obtained. 
     For such problems, anti-shake mechanisms utilizing motors were devised to move the image sensor to the image plane of the object when camera shake occurs. However, such motors are miniaturization and energy-inefficient vis-à-vis lens modules thus warranting an improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the disclosure 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 camera module. Moreover, in the drawings, all the views are schematic, and like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  a sectional view of a camera module, in accordance with an exemplary embodiment. 
         FIG. 2  is a cross sectional view of the camera module corresponding to  FIG. 1 , which is taken from line II-II. 
         FIG. 3  is a side plan view showing a light path in a normal state of a lens and an image sensor of the camera module of  FIG. 1  relative to an object. 
         FIG. 4  is a top plan view illustrating displacement of the lens and the image sensor relative to the object due to shaking of the camera module. 
         FIG. 5  is a side plan view corresponding to  FIG. 4 , which illustrates the light path of  FIG. 2  deviated by the displacement of the lens and the image sensor relative to an object. 
         FIG. 6  is similar to  FIG. 4 , but showing correction of the displacement of the image sensor. 
         FIG. 7  is a side plan view corresponding to  FIG. 6 , which illustrates correction of the deviated light path of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the camera module will now be described in detail below and with reference to the drawings. 
     Referring to  FIG. 1 , an exemplary camera module  100  in accordance with an exemplary embodiment is shown. The camera module  100  includes a fixture  10 , a lens module  20 , a movable frame  30 , an image sensor  40 , a position sensor  50 , a first magnet  72 , a second magnet  74  (see  FIG. 2 ), a first magnetic field generator  82 , and a second magnetic field generator  84  (see  FIG. 2 ). 
     The fixture  10  is configured to hold the lens module  20 , the frame  30 , the first magnetic field generators  82 , and the second magnetic field generator  84 . The fixture  10  includes a top board  110 , a hole  130 , and a pedestal  150 . The hole  130  is defined in a central portion of the top board  110 . The pedestal  150  extends downwardly from a peripheral portion of the top board  110 . The top board  110  and the pedestal cooperate to define a first receiving space  170 . A cross-section of the pedestal  150  is substantially rectangular, and the pedestal  150  includes four interior periphery sidewalls, for example, two parallel first periphery sidewalls  152  and two parallel second periphery sidewalls  154 . Each of the first periphery sidewalls  152  is located between, and adjoins the two periphery sidewalls  154 . 
     Referring also to  FIG. 2 , the lens module  20  includes a barrel  23  having a through hole  25 , and a lens  27  received in the through hole  25 . The barrel  23  is attached to the top board  110  and secured in the first receiving space  170 . An optical axis of the lens  27  is parallel to a Z-axis of a Cartesian coordinate system. In this embodiment, a cross-section of the barrel  23  is substantially rectangular, and the through hole  25  is substantially round. In alternative embodiments, the cross-section of the barrel  23  and the through hole  25  can be substantially round. The barrel  23  is attached to the top board  110 , and the hole  130  in the top board  110  communicates with the through hole  25  of the barrel  23 . 
     The frame  30  is spaced a distance from the top board  110  of the fixture  50  by four holding wires  60 . The frame  30  includes a base board  310  and a holder  350 . The holder  350  extends upwardly from a peripheral portion of the base board  310  toward the top board  110 . The base board  310  and the holder  350  cooperate to define a second receiving space  370  for substantially receiving the image sensor  40 . A cross-section of the holder  350  is substantially rectangular, and the holder  350  includes four exterior periphery sides, for example, two parallel first periphery sides  352  and two parallel second periphery sides  354 . Each of the first periphery sides  352  is located between and adjoins the two second periphery sides  354 . The holding wires  60  are fixed between the holder  350  and the top board  110  to hold the frame  30 . In this embodiment, the number of the holding wires  60  is four. The four holding wires  60  are fixed to a distal end of the holder  350  and located adjacent to the first and second periphery sides  352 ,  354 , respectively. The holding wires  60  can for example be made of metal. The flexibility of the holding wires  60  allows movement of the lens module  10  along an XY plane, which is perpendicular to the Z-axis. 
     The image sensor  40  can be a charge-coupled device (CCD) or a complementary metal oxide semiconductor device (CMOS), and is attached to the frame  30 . In this embodiment, the camera module  100  further includes a circuit board  35  for mounting the image sensor  40  thereon. The circuit board  35  is attached to the base board  310  at a side thereof facing away from the holder  310 . The base board  310  further has a hole  330  defined in the central region thereof to expose the circuit board  35 . The image sensor  50  is secured on the circuit board  35  and extends through the hole  330  to the second receiving space  370 , an essential part of the image sensor  40  is received in the second receiving space  370 . In alternative embodiments, the image sensor  40  can be directly mounted on the base board  310  and received in the second receiving space  370  without the circuit board  35 . 
     The position sensor  50  is mounted on the fixture  10 , and is capable of detecting position of at least one of the lens module  20  and the image sensor  40 . In particular, the position sensor  50  is mounted on the top board  110  of the fixture  10 . 
     The first magnets  72  and the second magnets  74  are mounted on the frame  30 . In this embodiment, the first and second magnets  72 ,  74  each can be a permanent magnet or an electromagnet, and are mounted to the two adjacent first and second periphery sides  352 ,  354  of the holder  350 . 
     The first magnetic field generator  82  and the second magnetic field generator  84  are mounted on the fixture  10 . In this embodiment, the first and second magnetic field generators  82 ,  84  are mounted on two first and second peripheral sidewalls  152 ,  154  of the pedestal  150 . The first magnetic field generator  82  is located adjacent, for example, opposite the first magnet  72 . The second magnetic field generator  84  is located adjacent, for example, opposite the second magnet  74 . 
     The first and second magnetic field generators  82 ,  84  are configured to generate a magnetic field around the respective first and second magnet  72 ,  74 . Preferably, the frame  30  may be made of metallic material for blocking the first and second magnets  72 ,  74 , as well as the first and second magnetic field generators  82 ,  84  from causing electromagnetic interference to the image sensor  40 . In addition, gaps (not labeled) are maintained between the first and second magnets  72 ,  74  and the respective first and second magnetic field generators  82 ,  84 , for allowing the lens module  10  to be movable along the XY plane. In this embodiment, each of the first and second magnetic field generators  82 ,  84  can be an electromagnetic coil. In operation of the first and second magnetic field generators  82 ,  84 , a current is applied to at least one of the first and second magnetic field generators  82 ,  84 . Either or both of the first and second magnetic field generators  82 ,  84  thus generate(s) a magnetic field around the respective first or/and the second magnet  72 ,  74 . As such, an electromagnetic force is generated between either or both of the first and second magnetic field generators  82 ,  84  and the respective first or/and the second magnet  72 ,  74 . The first and second magnet  72 ,  74  are subject to electromagnetic force along four different directions in the XY-plane, depending on the direction of the current in either or both of the first and second magnetic field generators  82 ,  84 . In particular, for the first magnet  72 , the electromagnetic force may operate in positive or negative Y directions. For the second magnet  74 , the electromagnetic force may operate in positive or negative X directions. In this way, the first and second magnets  72 ,  74  are capable of being selectively moved along the four axial directions in the XY plane, and the first and second magnets  72 ,  74  accordingly move the lens module  10  along selected of the four axial directions in the XY plane simultaneously. Furthermore, when the current is switched off, the lens module  10  can return to an original position due to the resilience of the holding wires  60 . 
     The camera module  100  may further include a controller  90 . The controller  90  is configured for applying current to the first and second magnetic field generators  82 ,  84 , as well as controlling the magnitude, direction, and duration of the current based on the motions of the lens module  10  and the image sensor  40 . 
     In use, when the camera module  100  is not performing anti-shake function(s), the holding wires  60  are parallel to each other, and parallel to an optical axis of the lens module  10 . In contrast, during camera shake of camera module  100 , the shaking may for example lead to motions of the camera module  100  along the X, Y, and Z axes. 
     Referring to  FIG. 3 , in one example, the camera module  100  operates in a normal image capturing state, an exemplary light beam from an object  102  transmits in an intended path through the lens  27  to arrive at a central region of the image sensor  40 . The image sensor  40  senses the light beam, thus generates a clear image  104  of the object. In this state, the controller  90  does not need to apply current to the first or second magnetic field generators  82 ,  84 . 
     Referring to  FIGS. 4 and 5 , in another example, shaking of the camera module  100  occurs, the lens  27  and the image sensor  40  are displaced from their respective original positions  27 ′,  40 ′. For example, each of the lens  27  and the image sensor  40  is displaced a distance X 1  along the positive direction of the X-axis, and a distance Y 1  along the negative direction of the Y-axis, as shown in  FIG. 4 . In this state, if no correction were made to the displacement of the lens  27  or the displacement of the image sensor  40 , the exemplary light beam from an object  102  would fall on a region of the image sensor  40  deviated from the central region, and generate a blurred image  106  on the image sensor  40 , as shown in  FIG. 5 . 
     Referring to  FIGS. 6 and 7 , in yet another example, corrections to the displacement of the image sensor  40  are made. The lens  27  is moved back a distance X 2  along the negative direction of the X-axis, and back a distance Y 2  along the positive direction of the Y-axis, as shown in  FIG. 6 . Thus, the optical light path of the exemplary light beam from the object  102  is compensated. Accordingly, the exemplary light beam from the object  102  falls on the central region of the image sensor  40 , and forms an image  108 , as shown in  FIG. 7 . The position of the image  108  is similar to, or substantially the same as the position of the image  104 . Thus, the exemplary light beam of the object  106  is still correctly and clearly projectable onto the central region of the image sensor  40  in spite of the shaking, hence successful anti-shake execution. 
     It is understood that the above-described embodiment are intended to illustrate rather than limit the disclosure. Variations may be made to the embodiment without departing from the spirit of the disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure.