Patent Publication Number: US-2019196137-A1

Title: Lens drive unit

Description:
TECHNICAL FIELD 
     The present invention relates to a lens drive unit. Specifically, the present invention relates to a lens drive unit that has an autofocus function. 
     BACKGROUND ART 
     A recent information processing terminal such as a smartphone and a tablet terminal is equipped with a compact camera module for taking an image. Such a camera module includes a lens drive unit that has an autofocus function to automatically focus at the time of taking an image of an object. 
     The autofocus function of the lens drive unit is realized by a voice coil motor including a magnet and a coil as shown in Patent Document 1, for example. Use of a drive force of the voice coil motor allows a lens to reciprocate along the optical axis direction. With this, the lens drive unit supports the reciprocation of the lens along the optical axis direction by the autofocus function with the use of a guide ball placed around. 
     Patent Document 1: Japanese Unexamined Patent Application Publication No. JP-A 2015-180937 
     In the lens drive unit having the autofocus function described above, there is a need to cause the lens to reciprocate in a stable manner when the lens moves along the optical axis direction. That is, there is a need to inhibit instability of the optical axis of the lens caused by the motion. Therefore, it is desired to increase stability of the lens during the reciprocation. 
     SUMMARY OF THE INVENTION 
     A lens drive unit as an aspect of the present includes: 
     a voice coil motor installed around a lens barrel equipped with a lens, the voice coil motor being configured to move the lens barrel along an optical axis of the lens; and 
     a guide part configured to guide movement of the lens barrel along the optical axis of the lens with respect to a housing configured to house the lens barrel. 
     The voice coil motor includes a magnet that is installed on one of the housing and the lens barrel and a coil and a yoke that are installed on the other, and the yoke is configured to concentrate a magnetic flux produced by the magnet. 
     The yoke is placed so as to press the lens barrel against the guide part by a magnetic force by which the yoke is attracted to the magnet. 
     Moreover, in the lens drive unit: 
     at least two voice coil motors are arranged around the lens barrel; and 
     yokes included by the at least two voice coil motors are arranged so as to press the lens barrel against the guide part by a resultant force of magnetic forces by the yokes. 
     Moreover, in the lens drive unit: 
     the guide part is placed in a middle position between the two voice coil motors around the lens barrel; and 
     the yokes included by the two voice coil motors are arranged so as to press the lens barrel against the guide part by a resultant force of magnetic forces by the yokes. 
     Moreover, in the lens drive unit, the voice coil motors are installed in positions corresponding to centers of neighboring side walls of the housing that has a rectangular shape. 
     Moreover, in the lens drive unit, the yoke is formed so that its portion on a side where the guide part is located is larger in cross section than its portion on a side where the guide part is not located. 
     Moreover, in the lens drive unit, the yoke has a T-shaped form and is installed so that a head part of the T-shaped form is placed closer to the guide part. 
     Moreover, in the lens drive unit, a magnetic force by which the yoke included by the voice coil motor installed on one of the neighboring side walls of the housing is attracted to the magnet is different from a magnetic force by which the yoke included by the voice coil motor installed on the other is attracted to the magnet. 
     Moreover, in the lens drive unit, a thickness of the yoke included by the voice coil motor installed on one of the neighboring side walls of the housing that has the rectangular shape is different from a thickness of the yoke included by the voice coil motor installed on the other. 
     Moreover, the lens drive unit further includes a second guide part on an opposite side from the guide part across the lens barrel. 
     The second guide part includes a guide ball and a retaining member that is configured to retain the guide ball in a rotatable manner and a guide ball support part against which the guide ball is pressed by the retaining member, the guide ball and the retaining member and the guide ball support part are arranged so that the retaining member retains the guide ball from one side with respect to a line passing through a center of the lens and connecting the guide part with the second guide part and so that the guide ball support part is located on the other side. 
     The thickness of the yoke is regulated so that the retaining member presses the guide ball against the guide ball support part by a magnetic force by which the yoke is attracted to the magnet. 
     Moreover, in the lens drive unit: 
     the voice coil motors are placed on a side where the retaining member is placed and on a side where the guide ball support part is placed, respectively, with respect to the line passing through the center of the lens and connecting the guide part with the second guide part; and the thicknesses of the yokes are regulated so that the yoke of the voice coil motor on the side where the retaining member is placed is thinner than the yoke of the voice coil motor on the side where the guide ball support part is placed. 
     Moreover, in the lens drive unit, the yoke and the magnet are placed so that a position of the lens barrel with respect to the housing becomes a predetermined position with magnetic levitation by the yoke and the magnet. 
     Further, the present invention also provides a camera module equipped with the lens drive unit. 
     Further, a lens drive unit as an aspect of the present invention includes: 
     a lens barrel equipped with a lens; 
     a housing installed around the lens barrel and configured to house the lens barrel; 
     a first voice coil motor configured to move the lens barrel along an optical axis of the lens with respect to the housing; and 
     a first guide part configured to guide movement of the lens barrel with respect to the housing. 
     In the lens drive unit, the first voice coil motor includes a magnet that is installed on one of the housing and the lens barrel and also includes a coil and a yoke that are installed on the other, and the yoke is placed so as to press the lens barrel against the first guide part by a magnetic force by which the yoke is attracted to the magnet. 
     The lens drive unit further includes: 
     a support cover configured to support the housing on one face side of the lens; 
     a second voice coil motor configured to move the housing in a vertical direction to the optical axis of the lens with respect to the support cover; 
     a second guide part placed between the housing and the support cover so as to come in contact with the housing and the support cover and configured to guide movement of the housing with respect to the support cover; and 
     a connection member configured to connect the housing to the support cover. 
     In the lens drive unit, the second voice coil motor includes a magnet installed on one of the housing and the support cover and also includes a coil and a yoke installed on the other; and 
     the connection member is configured to connect the housing to the support cover with a constant distance kept. 
     Moreover, in the lens drive unit, the connection member is configured to apply a force attracting the housing and the support cover to each other via the second guide part. 
     Moreover, in the lens drive unit, the connection member is configured to be flexible in the vertical direction to the optical axis of the lens. 
     Moreover, in the lens drive unit, the connection member includes a tension spring configured to apply a force attracting the housing and the support cover to each other. 
     Moreover, in the lens drive unit, the second guide part includes a plurality of spherical objects arranged at positions previously set with respect to the support cover and configured to rotate at the arranged positions. 
     Moreover, in the lens drive unit, the second voice coil motor includes two voice coil motors configured to respectively move the housing in two linear directions orthogonal to each other on a vertical plane to the optical axis of the lens. 
     Moreover, in the lens drive unit: 
     the first voice coil motors are arranged at positions on two neighboring sides of the lens barrel having a substantially rectangular shape; 
     the first guide part is placed in a middle position between the two first voice coil motors; and 
     the yokes of the two first voice coil motors are arranged so as to press the lens barrel against the first guide part by a resultant force of magnetic forces by the respective yokes. 
     Moreover, in the lens drive unit: 
     the first guide part includes a main guide part and a sub guide part, the main guide part is placed near a corner between the two neighboring sides where the two first voice coil motors are arranged of the lens barrel having the substantially rectangular shape, and the sub guide part is placed near the other corner located diagonally to the corner where the main guide part is placed of the lens barrel having the substantially rectangular shape; 
     the magnetic forces by which the yokes included by the two first voice coil motors are attracted to the magnets are differentiated from each other; and 
     the sub guide part is configured to support press by the lens barrel urged to rotate about the main guide part by a resultant force of the magnetic forces by the respective yokes of the two first voice coil motors. 
     Moreover, in the lend drive unit, two voice coil motors serving as the second voice coil motor are arranged near positions on the other two sides that are different from the two neighboring sides where the first voice coil motors are arranged of the lens barrel having the substantially rectangular shape, and the two voice coil motors respectively move the housing in two linear directions orthogonal to each other on a vertical plane to the optical axis of the lens. 
     Further, the present invention also provides a camera module equipped with the lens drive unit. 
     Further, a lens drive unit as an aspect of the present invention includes: 
     a lens barrel equipped with a lens; 
     a housing installed around the lens barrel and configured to house the lens barrel; 
     a voice coil motor configured to move the lens barrel along an optical axis of the lens with respect to the housing; and 
     a guide mechanism configured to guide movement of the lens barrel along the optical axis of the lens with respect to the housing. 
     The guide mechanism includes a main guide part and a sub guide part, the main guide part is placed in a predetermined position around the lens barrel, and the sub guide part is placed in another position located opposite the predetermined position around the lens barrel where the main guide part is placed, across the lens barrel. 
     The voice coil motor includes a magnet installed on one of the housing and the lens barrel and also includes a coil and a yoke installed on the other, and is configured to apply a force pressing the lens barrel against the main guide part and a force by which the lens barrel pulls the housing via the sub guide part, by a magnetic force by which the yoke is attracted to the magnet. 
     Moreover, in the lens drive unit, the sub guide part includes a housed member housed in a concave formed on an inner face of the housing and configured to move along the optical axis of the lens in the concave part, and the sub guide part is configured so that the housed member is caught inside the housing and pulled toward the lens barrel. 
     Moreover, in the lens drive unit, an opening of the concave is formed so as to have a larger cross-sectional area than an internal space of the concave. 
     Moreover, in the lens drive unit, the sub guide part includes a sub guide ball serving as the housed member housed in the concave, a retaining part connected to the lens barrel and configured to retain the sub guide ball in a manner rotatable along the optical axis of the lens, and a pulling member configured to pull the sub guide ball toward the lens barrel. 
     Moreover, in the lens drive unit: 
     the retaining part is configured to extend so as to be inserted in the internal space of the concave from the outer perimeter of the lens barrel, thereby sandwiching and retaining the sub guide ball along the optical axis of the lens and also retaining the sub guide ball in a manner movable along a direction in which the retaining member extends; and 
     the pulling member is formed by a magnet that pulls the sub guide ball toward the lens barrel by a magnetic force, and is placed near a root of the retaining member located closer to the lens barrel than the concave part of the housing. 
     Moreover, the lens drive unit further includes a second voice coil motor configured to move the housing with the lens barrel housed in a vertical direction to the optical axis of the lens, and in the lens drive unit: 
     two voice coil motors are arranged near two neighboring sides of an outer perimeter of the lens barrel having a substantially rectangular shape; 
     two second voice coil motors are arranged near two neighboring sides of the outer perimeter of the lens barrel, different from where the voice coil motors are arranged; 
     the main guide part is placed near a corner between the two neighboring sides of the outer perimeter of the lens barrel where the two voice coil motors are arranged; and 
     the sub guide part is placed near another corner located diagonally to the corner of the lens barrel where the main guide part is placed, and the another corner is between the two neighboring sides of the outer perimeter of the lens barrel where the two second voice coil motors are arranged. 
     Further, the present invention provides a camera module equipped with two lens drive units adjacent to each other. 
     The two lens drive units are installed so that none of the second voice coil motors are located on at least one of sides where the lens drive units are located adjacent to each other. 
     Moreover, in the camera module, the two lens drive units are installed so that none of the second voice coil motors are located on sides where the lens drive units are located adjacent to each other. 
     According to the lens drive unit of the present invention, the lens barrel is pressed against the guide part that guides the movement of the lens barrel. Consequently, the lens barrel moves along the optical axis direction in a state pressed against the guide part. As a result, it is possible to increase stability at the time of movement of the lens barrel. 
     Further, according to the lens drive unit of the present invention, the lens barrel is pressed against the first guide part and movement in the optical axis direction is guided. Moreover, the housing that houses the lens barrel keeps a predetermined distance from the support cover, and movement in a direction vertical to the optical axis direction is guided by the second guide part. As a result, stability of movement of the lens can be increased by the autofocus function and the stabilizer function. 
     Further, according to the lens drive unit of the present invention, the lens barrel is pressed against the main guide part, and movement in the optical axis direction of the lens barrel is guided in a state that the lens barrel pulls the housing via the sub guide part. Thus, a position of the lens barrel in a vertical direction to the optical axis direction in the housing becomes stable, and stability of movement of the lens can be increased. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view showing a configuration of a camera module in a first exemplary embodiment of the present invention; 
         FIG. 2  is a view for describing the configuration and operation of an autofocus function of a lens drive unit mounted on the camera module disclosed in  FIG. 1 ; 
         FIG. 3  is a view showing an example of the shape of a yoke included by the camera module; 
         FIG. 4  is a view showing an example of a state where a lens barrel mounted on the camera module disclosed in  FIG. 1  is pressed against a guide ball; 
         FIG. 5  is a view showing the configuration of a guide mechanism mounted on the camera module disclosed in  FIG. 1 ; 
         FIG. 6  is a view showing an example of another configuration of the camera module; 
         FIG. 7  is a view showing an example of another configuration of the camera module; 
         FIG. 8  is a view showing a configuration of a camera module in a second exemplary embodiment of the present invention; 
         FIG. 9  is a view for describing an example of a stabilizer function; 
         FIG. 10  is a view showing a configuration of a camera module in a third exemplary embodiment of the present invention; 
         FIG. 11  is a view showing a configuration of a lens barrel included by the camera module; 
         FIG. 12  is a view showing a configuration of a housing included by the camera module; 
         FIG. 13  is a view showing a configuration of a cover and a bottom cover that are included by the camera module; 
         FIG. 14  is a view showing a configuration of an FPC included by the camera module; 
         FIG. 15  is a view showing a configuration of a magnet and a coil that are included by the camera module; 
         FIG. 16  is a view showing a configuration of a magnet and a coil that are included by the camera module; 
         FIG. 17  is a view showing a configuration of a yoke included by the camera module; 
         FIG. 18  is a view showing how the camera module is assembled; 
         FIG. 19  is a view showing an operation of the camera module; 
         FIG. 20  is a view showing an operation of the camera module; 
         FIG. 21  is a view showing a configuration of a camera module in a fourth exemplary embodiment of the present invention; 
         FIG. 22  is a magnified view showing a configuration of part of the camera module disclosed in  FIG. 21 ; 
         FIG. 23  is a view showing components of the part of the camera module disclosed in FIG.  22 ; 
         FIG. 24  is a view showing an operation of the camera module disclosed in  FIG. 21 ; 
         FIG. 25  is a view showing an operation of the camera module disclosed in  FIG. 21 ; 
         FIG. 26  is a view showing an example of arrangement of a camera module in a fifth exemplary embodiment of the present invention; 
         FIG. 27  is a view showing an example of arrangement of the camera module in the fifth exemplary embodiment of the present invention; and 
         FIG. 28  is a view showing an example of arrangement of the camera module in the fifth exemplary embodiment of the present invention. 
     
    
    
     EXEMPLARY EMBODIMENT 
     First Exemplary Embodiment 
     A first exemplary embodiment of the present invention will be described with reference to  FIGS. 1 to 7 .  FIG. 1  is a view showing a configuration of a camera module  1 .  FIG. 2  is a view for describing the configuration and operation of an autofocus function of a lens drive unit mounted on the camera module  1 .  FIG. 3  is a view showing an example of the shape of a yoke included by the camera module  1 .  FIG. 4  is a view showing an example of a state where a lens barrel  12  mounted on the camera module  1  is pressed against a guide ball  61  and a guide ball  65 .  FIG. 5  is a view showing the configuration of a guide mechanism mounted on the camera module  1 .  FIGS. 6 and 7  are views showing examples of other configurations of the camera module  1 . 
     The camera module  1  according to the present invention is, for example, for taking an image, mounted on an information processing terminal such as a smartphone and a tablet terminal. However, the camera module  1  according to the present invention is not necessarily limited to being mounted on an information processing terminal, and may be mounted on other electronic equipment or various types of equipment. 
     The camera module  1  includes a lens drive unit that has an autofocus function to automatically focus at the time of taking an image of an object. Hereinafter, a configuration of the lens drive unit that realizes the autofocus function will be mainly described. The lens drive unit may have a function other than the function illustrated in this exemplary embodiment, for example, may have a stabilizer function to optically compensate for camera shake occurring at the time of taking an image to reduce blur of the image. 
     First, the outline of the configuration of the camera module  1  will be described with reference to  FIG. 1 . The upper view of  FIG. 1  is a view showing the inside of the camera module  1  taken from above. The lower view of  FIG. 1  is a partial sectional view showing the inside of the camera module  1  taken from the lower side in the upper view of  FIG. 1 . 
     With reference to the lower view of  FIG. 1 , the camera module  1  is surrounded by a bottom substrate  21  and a cover  22 . On the bottom substrate  21 , a FPC (Flexible Printed Circuit)  31  having an imaging element and a FP coil (Fine Pattern coil)  32  are laminated. 
     Further, the camera module  1  has a rectangular housing  33  surrounded by a bottom part and side walls above the FP coil  32 . The housing  33  houses the lens barrel  12  equipped with a lens  11 , and the lens barrel  12  is, in planar view, located in a circular cutout part formed in the bottom part of the housing  33 . The lens barrel  12  is supported in the housing  33  by the guide ball  61 , the guide ball  65  and so on to be described later. The lens barrel  12  is then supported so that the direction of the optical axis of the lens  11  mounted on the lens barrel  12  is a direction vertical to the surface of paper in the upper view of  FIG. 1  and is a direction along the surface of paper in the lower view of  FIG. 1 . 
     Further, the camera module  1  includes a lens drive unit that drives the lens barrel  12  equipped with the lens  11 . The lens drive unit includes, as the configuration realizing the autofocus function, voice coil motors placed around the lens barrel  12 . The voice coil motors are placed around the lens barrel  12 , in positions corresponding to the middles of two neighboring side walls of the rectangular housing  33 , respectively. That is, in this exemplary embodiment, as shown in the upper view of  FIG. 1 , one of the voice coil motors is placed on an extended line (a dashed-dotted line C 1 ) of a predetermined diameter of the lens  11 . Moreover, the other voice coil motor is placed on an extended line (a dashed-dotted line C 2 ) of a diameter of the lens  11  that intersects the dashed-dotted line C 1  at right angles. 
     The voice coil motors each include a coil  51  and a yoke  52  installed on the housing  33 , and a magnet  53  installed on the lens barrel  12  so as to correspond to the coil  51  and the yoke  52 . To be specific, the voice coil motor placed on the dashed-dotted line C 1  includes a coil  51   a , a yoke  52   a  and a magnet  53   a , and the voice coil motor placed on the dashed-dotted line C 2  includes a coil  51   b , a yoke  52   b  and a magnet  53   b . Hereinafter, when not particularly discriminated, the components will be referred to as the coil  51 , the yoke  52  and the magnet  53 . 
     Of the components described above, the coil  51   a  and the coil  51   b  have the same configurations, and the magnet  53   a  and the magnet  53   b  also have the same configurations. Moreover, as described later, both the yoke  52   a  and the yoke  52   b  have T-shaped forms and are different in thickness of long and thin leg parts of the T-shaped forms. Hereinafter, a detailed configuration and operation of the voice coil motors will be described with reference to  FIG. 2 . 
     As shown in  FIG. 2 , the coil  51  is placed so as to face the lateral surface of the lens barrel  12 . The coil  51  is formed into a ring-like shape so that wires are located on the upper side and the lower side in  FIG. 2  (that is, on the upper side and the lower side in the lower view of  FIG. 1 ). 
     The yoke  52  is placed outside the coil  51 . The yoke  52  focuses a magnetic flux produced by the magnet  53 . The yoke  52  is made of, for example, a soft magnetic material such as iron with few impurities and is fixed on, for example, the housing  33 . 
     The yoke  52  is placed so that a head part (a thickened part) of its T-shaped form is directed to the other yoke  52 . For example, the yoke  52   a  is placed so that a head part of its T-shaped form is directed to the yoke  52   b . Likewise, the yoke  52   b  is placed so that a head part of its T-shaped form is directed to the yoke  52   a . In other words, the head part of the yoke  52   b  is arranged on the left side in the upper view of  FIG. 1 , and the head part of the yoke  52   a  is arranged on the lower side in the upper view of  FIG. 1 . It can also be said that the yoke  52  has the head part on a side where a guide mechanism to be described later exists. 
     The yoke  52   a  and the yoke  52   b  in this exemplary embodiment are different in thickness of long and thin leg parts formed below the head parts of the T-shaped forms. For example, the upper view of  FIG. 3  shows an example of the yoke  52   a , and the lower view of  FIG. 3  shows an example of the yoke  52   b . With reference to  FIG. 3 , the long and thin leg part of the yoke  52   a  is thinner than that of the yoke  52   b.    
     Further, the magnet  53  is placed opposite the coil  51 , in the vicinity of the lateral surface of the lens barrel  12 . The magnet  53  is magnetized so that the upper part of a face opposite the lens barrel  12  is the N pole and the lower part is the S pole. 
     The voice coil motor has the configuration as described above, for example. Herein, electric power is supplied to the coil  51  by wires  34  installed on the four corners of the housing  33  and springs (not shown in the drawings) connected to the wires, and so on. 
     Applying electric current to the coil  51  causes the voice coil motor having the configuration as described above to produce a drive force for moving the lens barrel  12  along the direction of the optical axis of the lens  11 . That is, when electric current is applied to the coil  51 , because of the direction of the electric current and magnetic fluxes shown with curved arrows passing through the coil  51  from the magnet  53 , the lens barrel  12  can move upward or downward (directions of an arrow Y 1 ) on the surface of paper in accordance with the Fleming&#39;s left-hand rule. Thus, the voice coil motors cause the lens barrel  12  to reciprocate along the direction of the optical axis of the lens  11 . 
     The configuration of the voice coil motor described above stabilizes the position of the lens barrel  12  as described below. Magnetic fluxes passing through the yoke  52  from the magnet  53  are produced. The yoke  52  has a property of seeking to take the magnetic fluxes from the magnet  53  as much as possible. Therefore, the yoke  52  acts so as to be located opposite the center of the magnet  53 , that is, opposite the boundary of the N pole and the S pole. With such magnetic levitation, the lens barrel  12  connected with the magnet  53  levitates so that the yoke  52  is located at the boundary of the N pole and the S pole. Moreover, when the lens barrel  12  connected with the magnet  53  moves in accordance with the Fleming&#39;s left-hand rule and the yoke  52  is thereby dislocated upward or downward with respect to the center of the magnet  53 , a magnetic spring effect, which is trying to turn back to the original position with a magnetic force, arises. 
     Thus, the lens barrel  12  connected with the magnet  53  is stably located in a position corresponding to a position where the yoke  52  is installed. Therefore, for example, by setting a position of the lens barrel  12  due to magnetic levitation to a predetermined position such as a focus position, which is frequently used, it is possible to limit driving of the lens barrel  12  by the voice coil motors described above, and it is possible to achieve power saving. In other words, use of the voice coil motors described above enables control of the position of the lens barrel  12  with respect to the housing  33  or the like even when a position detection unit  68  to be described later is not used or even in an open loop controller that does not use electric current feedback. 
     Further, the lens drive unit includes, as the configuration realizing the autofocus function, a guide mechanism (a guide part) that guides reciprocation of the lens barrel  12  along the optical axis as described above. The guide mechanism is placed in the middle position between the two neighboring voice coil motors around the lens barrel  12 . That is, as shown in the upper view of  FIG. 1 , the lens drive unit includes the guide mechanism on an extended line C 3  of a diameter dividing into two between the dashed-dotted lines C 1  and C 2 , which are the two diameters passing through the center of the lens  11  and oing at right angles. Moreover, the lens drive unit includes a second guide mechanism on the extended line C 3  of the dividing diameter, on the opposite side from the guide mechanism across the lens barrel  12 . In other words, the guide mechanism and the second guide mechanism are installed diagonally on the housing  33  having a rectangular shape. 
     The abovementioned guide mechanism includes a guide ball retainer  62  installed on the lens barrel  12 , a guide ball support  63  installed on the housing  33 , and a guide ball  61  sandwiched by the guide ball retainer  62  and the guide ball support  63 . For example, the guide mechanism includes two guide balls  61  which are the same in size and placed along a direction vertical to the surface of paper in the upper view of  FIG. 1 . The number of the guide balls  61  included by the guide mechanism may be one, or may be three or more. 
     The guide ball retainer  62  retains the guide ball  61  in a rotatable manner. The guide ball support  63  has a groove along the optical axis of the lens  11  as a range where the guide ball  61  can move. Consequently, the guide ball  61  rotates and moves in the groove formed on the guide ball support  63  and, with this, the lens barrel  12  on which the guide ball retainer  62  is installed can move only in a direction along the groove formed on the guide ball support  63 . 
     Further, as described above, the lens drive unit includes the second guide mechanism. The second guide mechanism is a mechanism as a pair with the abovementioned guide mechanism. The second guide mechanism is placed on the opposite side from the guide mechanism across the lens barrel  12  around the lens barrel  12 . 
     The second guide mechanism includes a retaining member  66  installed on the lens barrel  12 , a guide ball support  67  formed on the housing  33 , and a guide ball  65  sandwiched by the retaining member  66  and the guide ball support  67 . As well as the guide mechanism described above, the second guide mechanism includes, for example, two guide balls  65  which are the same in size and placed along a direction vertical to the surface of paper in the upper view of  FIG. 1 . The number of the guide balls  65  included by the guide mechanism may be one, or may be three or more. 
     The retaining member  66  retains the guide balls  65  in a rotatable manner. For example, by sandwiching the guide balls  65  with a U-shaped sandwiching part, the retaining member  66  retains the guide balls  65  in a rotatable manner. The guide ball support  67  is a wall against which the guide balls  65  are pressed by the retaining member  66 . As described before, the guide ball support  67  is formed on the housing  33 . 
     As shown in  FIG. 1 , the retaining member  66  retains the guide balls  65  from one side with respect to the dashed-dotted line C 3 , which is a line passing through the center of the lens  11  and connecting the guide mechanism with the second guide mechanism. As described later, the retaining member  66  presses the guide balls  65  against the guide ball support  67  installed on the other side with respect to the dashed-dotted line C 3 . The guide ball support  67  may have a groove along the optical axis of the lens  11  as a range where the guide balls  65  can move. Thus, in the second guide mechanism, the retaining member  66  sandwiches the guide balls  65  from one side of the guide balls  65 . Moreover, the guide ball support  67  is located on the other side of the guide balls  65 . 
     Further, a position detection unit  68  that detects the position of the lens barrel  12  can be installed on the lens drive unit (the housing  33 ). The position detection unit  68  is formed by, for example, a hole element that detects the strength of a magnetic field. With the position detection unit  68 , it is possible to detect the position of the lens barrel  12 . 
     The above is a description of an example of the configuration of the camera module  1 . 
     As described above, in this exemplary embodiment, the yoke  52  fixed on the housing  33  and the magnet  53  are used. With such a configuration, the magnet  53  is attracted to the yoke  52  by a magnetic force which attracts the magnet  53  and the yoke  52  to each other, and consequently, the lens barrel  12  on which the magnet  53  is placed is attracted to the housing  33 . That is, a force (a magnetic force) in an arrow Y 4  direction obtained by combining a force in arrow Y 2  direction with a force in an arrow Y 3  direction in  FIG. 4  is applied to the lens barrel  12 . Moreover, in this exemplary embodiment, as described above, the T-shaped yokes  52  are used, and the yokes  52  are placed so that the head part of the T-shaped form of one yoke  52  is directed to the other. Such a configuration allows for making the magnetic flux density on the side where the other yoke  52  is placed higher than the magnetic flux density on the side where the other yoke  52  is not placed. In other words, for example, in the case shown in  FIGS. 1 and 4 , use of the yoke  52   b  allows for making the magnetic flux density on the left side of the yoke  52   b  higher than on the right side. Consequently, it is possible to more efficiently strengthen the force in the arrow Y 4  direction. In other words, the configuration in this exemplary embodiment can efficiently realize a state where the lens barrel  12  is pressed against the guide balls  61 . As a result, when the lens barrel  12  moves along the optical axis direction, the lens barrel  12  remains pressed against and supported by the guide balls  61 , so that it is possible to realize stable movement without instability of the optical axis. 
     Further, as described above, the long and thin leg part of the yoke  52   b  is thicker than that of the yoke  52   a . This makes the magnetic flux density of the voice coil motor including the yoke  52   b  higher than that of the voice coil motor including the yoke  52   a . As a result, a magnetic force by which the yoke  52   b  is attracted to the magnet  53   b  is stronger than a magnetic force by which the yoke  52   a  is attracted to the magnet  53   a , and a force in an arrow Y 5  direction in  FIG. 4  is applied to the lens barrel  12 . This causes the retaining member  66  to press the guide balls  65  against the guide ball support  67 , so that it is possible to realize stable movement without instability of the optical axis. 
     The configuration of the guide mechanism described above will be described in detail. As shown in  FIG. 5 , the guide ball retainer  62  is a spherical retainer having an opening, and its inner face holding a half or more of the guide ball  61  is a little larger than a hemisphere. Near the opening, the inner face of the guide ball retainer  62  has almost the same shape and size as the guide ball  61 , and the guide ball retainer  62  contacts and retains the guide ball  61  in a rotatable manner in the vicinity of the opening. On the other hand, near the innermost part, the internal face is formed larger than the outline of the guide ball  61 , and there is a space  62   a  between the guide ball retainer  62  and the guide ball  61  retained thereby. The guide ball retainer  62  in this exemplary embodiment retains the guide ball  61  with the space  62   a  from the guide ball  61  located on the line connecting the guide ball  61  and the center of the lens  11  (i.e., on the dashed-dotted line C 3 ) particularly as shown in the upper view of  FIG. 5 . 
     Thus, the guide ball retainer  62  in this exemplary embodiment retains the guide ball  61  only in the vicinity of a circle of a sphere intersecting with a plane passing near the center of the guide ball  61 . Consequently, a load radius is small, so that it is possible to make the movement resistance of the lens barrel  12  low. Moreover, because there is a space between the guide ball retainer  62  and the guide ball  61 , it is possible to inhibit increase of a load resistance due to wear debris or the like. 
     Further, the guide ball support  63  of the guide mechanism has the groove  63   a  holding part of the guide ball  61  along the optical axis direction, and the guide ball  61  is retained by the groove so as not to move off the optical axis direction. The shape of the groove  63   a  of the guide ball support  63  is like an arc which contacts part of the spherical surface of the guide ball  61  as shown in the upper view of  FIG. 5 , for example. However, the shape of the groove  63   a  of the guide ball support  63  is not limited to such a shape and, as shown in the upper view of  FIG. 5 , the groove may be formed by a plurality of surfaces formed to contact part of the spherical surface of the guide ball  61  at a plurality of points. 
     Thus, in the camera module  1  of this exemplary embodiment, the lens barrel  12  can be pressed against the guide balls  61 . Moreover, the guide balls  65  can be pressed against the guide ball support  67  by the retaining member  66 . Consequently, the stability of the lens barrel  12  at the time of movement can be increased. That is, according to this exemplary embodiment, the yokes  52  are arranged so as to press the lens barrel  12  against the guide mechanism by a magnetic force by which the yokes  52  and the magnets  53  are attracted to each other, so that the stability of the lens barrel  12  at the time of movement can be increased. 
     According to the present invention, the number and arrangement of the voice coil motors or the number and arrangement of the guide mechanisms (the guide balls) and the second guide mechanisms are not limited to those described above. Moreover, the shape of the yoke  52  is not limited to that described above. 
     For example, as shown in  FIG. 6 , the yoke  52  may be formed into a rod-like shape or the like. With reference to the upper view and the lower view of  FIG. 6 , the rod-like yoke  52  is placed on a side close to the other yoke  52  (i.e., in the position where the head part of the abovementioned T-shaped yoke  52  lies). Such a configuration can also increase the force in the arrow Y 4  direction in  FIG. 4 . Moreover, as a shape that a part on a side close to the guide mechanism is larger in cross section area than a part on a side far from the guide mechanism, the yoke  52  may be formed into a shape other than the T shape. For example, the yoke  52  may be formed into a triangular shape or the like. 
     Further, as for the yokes  52 , the yoke  52   a  and the yoke  52   b  may be formed into plates with different thicknesses. Thus, the yoke  52   a  and the yoke  52   b  may be formed into a shape other than the shape illustrated in this exemplary embodiment, which is a shape that a magnetic force by which the yoke  52   a  is attracted to the magnet  53   a  is different from a magnetic force by which the yoke  52   b  is attracted to the magnet  53   b.    
     Thus, the shape of the yoke  52  is not necessarily limited to a T-shaped form. Moreover, by controlling the magnets  53  instead of controlling the shape or the like of the yokes  52  or in addition to controlling the shape of the yokes  52 , the yokes  52  may be configured so that a magnetic force by which the yoke  52   a  is attracted to the magnet  53   a  is different from a magnetic force by which the yoke  52   b  is attracted to the magnet  53   b.    
     Further, for example, as shown in  FIG. 7 , the voice coil motors may be arranged around the lens barrel  12 , on the opposite sides from each other across the lens barrel  12 . That is, as shown in  FIG. 7 , two voice coil motors may be arranged across the lens barrel  12  on an extended line of a predetermined diameter of the lens  11  (i.e., on the dashed-dotted line C 1 ). In other words, the voice coil motors can be arranged in the middles of the opposite side walls of the rectangular housing  33 , respectively. 
     In this case, the head parts of the Y-shaped yokes  52  are arranged in the same direction to press the lens barrel  12  (a direction where the guide mechanism is installed). For example, in the case shown in  FIG. 7 , the yokes  52  are arranged so that the head parts of the yokes  52  are located toward the lower side in  FIG. 7 . Also with such a configuration, it is possible to keep the lens barrel  12  pressed against the guide balls  61 , so that it is possible to realize stable movement without instability of the optical axis. 
     Further, in the case shown in  FIG. 7 , the guide mechanism is placed in the middle position of the two voice coil motors around the lens barrel  12 , for example. That is, as shown in  FIG. 7 , in a case where the two voice coil motors are arranged on the dashed-dotted line C 1 , the guide mechanism is placed on an extended line (the dashed-dotted line C 2 ) of a diameter orthogonal to the diameter (the dashed-dotted line C 1 ). In other words, the guide mechanism can be placed in the middle of a side wall sandwiched by the opposite side walls of the housing  33  where the two voice coil motors are arranged, respectively. 
     Further, the second guide mechanism is placed on the opposite side from the guide mechanism across the lens barrel  12  around the lens barrel  12 . That is, the second guide mechanism can be placed in the middle of a side wall where the guide mechanism is not placed of the side walls sandwiched by the opposite side walls of the housing  33  where the two voice coil motors are placed, respectively. 
     Furthermore, in the case shown in  FIG. 7 , as the second guide mechanism, a cylindrical or spherical fixed member  71  installed on the housing  33  and a U-shaped sandwiching member  72  installed on the lens barrel  12  can be employed. The U-shaped sandwiching member  72  is placed while sandwiching the fixed member  71  in the open space of the U-shaped part. Because the open space of the U-shaped part of the sandwiching member  72  has a predetermined length in depth, the fixed member  71  can move inside the open space. That is, in the case shown in  FIG. 7 , the sandwiching member  72  can move with respect to the fixed member  71  only in a direction along a line connecting the guide mechanism with the second guide mechanism (i.e., on the dashed-dotted line C 2 ), and consequently, the lens barrel  12  can move along the line (the dashed-dotted line C 2 ). Thus, with a space between the U-shaped sandwiching member  72  and the fixed member  71 , it is possible to appropriately control a situation that the lens barrel  12  is pressed against the guide balls  61 , and it is possible to realize stable support and movement. 
     In this exemplary embodiment, a case where the lens barrel  12  has the magnet  53  and the housing  33  has the coil  51  and the yoke  52  has been described. However, for example, the camera module may be configured so that the lens barrel  12  has the coil  51  and the yoke  52  and the housing  33  has the magnet  53 . 
     Second Exemplary Embodiment 
     Next, a second exemplary embodiment of the present invention will be described with reference to  FIGS. 8 and 9 .  FIG. 8  is a view showing a configuration of the camera module  1  in this exemplary embodiment.  FIG. 9  is a view showing an operation of the lens drive unit. 
     As shown in  FIG. 8 , the lens drive unit of the camera module  1  in this exemplary embodiment includes, in addition to the configurations described in the first exemplary embodiment, an OIS (Optical Image Stabilizer) magnet  81  as a configuration realizing a stabilizer function. 
     With reference to  FIG. 8 , the OIS magnets  81  are installed on the dashed-dotted line C 1  on the opposite side from the voice coil motor (the coil Ma) across the lens barrel  12 , and on the dashed-dotted line C 2  on the opposite side from the voice coil motor (the coil  51   b ) across the lens barrel  12 . 
     As shown in  FIG. 9 , each of the OIS magnets  81  is magnetized so that a face opposite the FP coil  32  is an N pole and an S pole. A coil is formed at a part of the FP coil  32  opposite each of the OIS magnets  81 . Consequently, when electric current is applied to the coil, because of a magnetic flux produced by the OIS magnet  81  and the electric current, it is possible to move the housing  33 , that is, the lens barrel  12  in an arrow Y 6  direction (i.e., along the surface of paper of the upper view of  FIG. 1 ) in accordance with the Fleming&#39;s left-hand rule. Thus, it is possible to realize the stabilizer function with a simple configuration. 
     Third Exemplary Embodiment 
     A third exemplary embodiment of the present invention will be described with reference to  FIGS. 10 to 19 .  FIG. 10  is a view showing a configuration of a camera module  101 .  FIGS. 11 to 16  are views showing components included by the camera module.  FIG. 17  is a view showing how the camera module is assembled.  FIGS. 18 to 19  are views showing an operation of the camera module. 
     The camera module  101  according to the present invention is, for example, for taking an image, mounted on an information processing terminal such as a smartphone and a tablet terminal. However, the camera module  101  according to the present invention is not necessarily limited to being mounted on an information processing terminal. The camera module  101  may be mounted on other electronic equipment or various types of equipment. 
     The camera module  101  according to the present invention includes a lens drive unit which has an autofocus function and a stabilizer function; the autofocus function automatically focuses at the time of taking an image of an object, and the stabilizer function optically compensates for camera shake occurring at the time of taking an image to reduce blur of the image. Hereinafter, a configuration of the lens drive unit for realizing the autofocus function and the stabilizer function will be mainly described. Meanwhile, the lens drive unit may have a function other than the functions illustrated in this exemplary embodiment. 
     [Configuration] 
     First, the overall configuration of the camera module  101  will be described with reference to  FIG. 10 .  FIG. 10  shows a plan view and side views of the camera module  101 . In the drawings of this application, the configuration is partly made to be transparent or omitted for the purpose of clarifying the structure. 
     First, the camera module  101  includes a cover  105  which covers the top and a bottom cover  106  which covers the bottom. In  FIG. 10 , the top face and side faces of the cover  105  are illustrated in a perspective manner so as to be transparent. The camera module  101  includes a lens barrel  103  equipped with a lens  102 , and a housing  104  surrounding the lens barrel  103  and housing the lens barrel  103 , inside the cover  105  and the bottom cover  106  (a support cover). In addition, the camera module  101  includes two first voice coil motors  171 - 173  that move the lens barrel  103  along the direction of the optical axis of the lens  102  with respect to the housing  104 , and two first guide parts  176  and  177  that guide movement of the lens barrel  103  with respect to the housing  104 . Mainly, by the first voice coil motors  171 - 173  and the first guide parts  176  and  177 , the autofocus function of the lens  102  is realized. 
     Further, the housing  104  is supported by the bottom cover  106  on the bottom face side (one face side) of the lens  102 , and the camera module  101  includes second voice coil motors  174 - 175  which move the housing  104  in a vertical direction to the direction of the optical axis of the lens  102  with respect to the bottom cover  106 . In addition, the camera module  101  includes second guide parts  178  that are placed between the housing  104  and the bottom cover  106  to guide movement of the housing  104  with respect to the second voice coil motors  174 - 75 , and connection springs  79  (connection members) that connect the housing  104  to the bottom cover  106 . Mainly by these components, the stabilizer function of the lens  102  is realized. 
     Further, the camera module  101  includes a FPC (Flexible Printed Circuit)  108 , and other components. Hereafter, the respective components will be described. 
     With reference to  FIG. 11 , the configuration of the lens barrel  103  will be described.  FIG. 11  shows a plan view and side views of the lens barrel  103 . The lens barrel  103  has a substantially rectangular outline. At the center of the lens barrel  103 , a lens housing hole that houses the lens  102  is formed. 
     Further, concave parts  133  and  134  that are dented inward are formed on side faces of the lens barrel  103 . To be specific, the concave parts  133  and  134  are formed on, of the side faces of the lens barrel  103 , two side faces corresponding to two neighboring sides of the substantially rectangular outline, closer to a corner at the intersection of the two sides, respectively. In the concave parts  133  and  134 , magnets  171   a  and  171   b  configuring the first voice coil motors are placed, respectively. The first voice coil motors move the lens barrel  103  along the direction of the optical axis of the lens  102 , and are configured by the magnets  171   a  and  171   b , and coils  172   a  and  172   b  and yokes  173   a  and  173   b  that are arranged on the housing  104  so as to be opposite the magnets  171   a  and  171   b  (as described later), respectively. Thus, the first voice coil motors that realize the autofocus function are arranged on the two side faces corresponding to the two neighboring sides of the substantially rectangular outline. 
     Further, a first guide ball retaining part  131  is formed at a corner sandwiched by the two neighboring sides of the substantially rectangular lens barrel  103  on which the two first voice coil motors are placed. The first guide ball retaining part  131  is formed by a groove along the direction of the optical axis of the lens  102 , and the groove is open outward on a diagonal line that passes the corner with the groove formed. Then, the first guide ball retaining part  131  retains a spherical main guide ball  176  (a main guide part) as part of the first guide part, in a rotatable manner. The main guide ball  176  is pressed against and supported by a first guide ball support part  141  formed on the inner surface of the housing  104  to be described later. Consequently, the main guide ball  176  rotates in the groove serving as the first guide ball retaining part  131  and, with this, the lens barrel  103  is guided by the main guide ball  176  to move along the direction of the optical axis of the lens  102 . In  FIG. 11 , two main guide balls  176  are retained in the groove serving as the guide ball retaining part  131 , but any number of main guide balls  176  may be retained. 
     Further, on the lens barrel  103 , a second guide ball retaining part  132  is formed at the other corner located diagonally to the corner where the first guide ball retaining part  131  is formed. The second guide ball retaining part  132  is formed into a substantially spherical hole, and the hole is open in a direction orthogonal to the diagonal line that passes the corner with the hole formed. The second guide ball retaining part  132  retains a spherical sub guide ball  177  (a sub guide part), which is part of the first guide part, in a rotatable manner. The sub guide ball  177  is pressed against and supported by a second guide ball support part  142  formed on the inner face of the housing  104  to be described later. Consequently, the sub guide ball  177  rotates in the hole serving as the second guide ball retaining part  132  and, with this, the lens barrel  103  moves along the direction of the optical axis of the lens  102 . 
     Further, the lens barrel  103  may include a position detection mechanism that detects the position of the lens barrel  103  along the direction of the optical axis of the lens  102 . The position detection mechanism includes, for example, a magnet and a hole element that detects the strength of a magnetic field, and may be configured so that the magnet is placed on the lens barrel  103  and the hole element is placed on the housing  104  to be described later. 
     Next, with reference to  FIG. 12 , the configuration of the housing  104  will be described.  FIG. 12  shows a plan view, side views and a bottom view of the housing  104 . 
     The housing  104  is a tubular member formed by four side walls and having a substantially rectangular end face. Inside the housing  104 , the lens barrel  103  equipped with the lens  102  is housed, and the components configuring the first voice coil motors are included. Moreover, the housing  104  is equipped with components configuring the second voice coil motors to be described later. 
     To be specific, the first guide ball support part  141  that has a concave shape and receives the main guide ball  176  is formed on the inner surface at one corner of the housing  104 , that is, on the inner surface at a corner corresponding to the first guide ball retaining part  131  formed on the lens barrel  103  housed in the housing  104 . Moreover, the second guide ball support part  142  that has a concave shape and receives the sub guide ball  177  is formed on the inner surface at the other corner located diagonally to the one corner, that is, on the inner surface at a corner corresponding to the second guide ball retaining part  132  formed on the lens barrel  103  housed in the housing  104 . 
     Further, on two of the side walls of the housing  104 , first concave parts  143  and  144  are formed by forming the inner surfaces of the side walls themselves into concave shapes, respectively. To be specific, the first concave parts  143  and  144  are formed, respectively, at positions opposite the magnets  171   a  and  171   b  mounted on the lens barrel  103  housed inside the housing  104  on the side walls of the housing  104 . The coils  172   a  and  172   b  and the yokes  173   a  and  173   b  configuring the first voice coil motors, respectively, are arranged in the first concave parts  143  and  144 , respectively. 
     Further, the bottom faces of the side walls of the housing  104  are dented upward as second concave parts  145  and  146 . To be specific, the second concave parts  145  and  146  are formed, respectively, on the bottom faces on, of the side walls of the housing  104 , side walls corresponding to two neighboring sides of the substantially rectangular outline where either the first concave part  143  or  144  is not formed. Then, magnets  174   a  and  174   b  configuring the second voice coil motors are arranged in the second concave parts  145  and  146 , respectively. The second voice coil motors allow movement of the housing  104  that houses the lens barrel  103  along a vertical plane to the direction of the optical axis of the lens  102 , and include the magnets  174   a  and  174   b , and coils  175   a  and  175   b  placed on the bottom cover  106  as described later, respectively. Then, one of the second voice coil motors including the magnet  174   b  shown in  FIG. 10  moves the housing  104  along one linear direction (an X-axis direction) on the vertical plane to the direction of the optical axis of the lens  102 . Moreover, the other second voice coil motor including the magnet  174   a  moves the housing  104  along another linear direction (a Y-axis direction) orthogonal to the one linear direction on the vertical plane to the direction of the optical axis of the lens  102 . 
     Further, at the four corners on the bottom face of the housing  104 , cutout parts  147  cut toward the top face are formed. In the four cutout parts  147 , connection springs  179  are housed, respectively. Therefore, the inner face of the ceiling of each of the cutout parts  147  is formed so that one end of the connection spring  179  gets caught. 
     Moreover, support guide ball receiving parts  148  formed into concave shapes to receive support guide balls  178  to be described later are formed at three places on the bottom surface of the housing  104 . 
     Further, the housing  104  may include part of a position detection mechanism that detects the position of the lens barrel  103  along the direction of the optical axis of the lens  102 . The position detection mechanism includes, for example, a magnet and a hole element that detects the strength of a magnetic field, and the hole element that detects the strength of the magnetic field of the magnet placed on the lens barrel  103  may be placed on the housing  104 . Moreover, the housing  104  may include a position detection mechanism that detects the position of the housing  104  in a direction vertical to the optical axis direction of the lens  102 , that is, the position with respect to the bottom cover  106 . For example, the position detection mechanism may be configured so that the magnet is placed on the housing  104  and the hole element is placed on the bottom cover  106 . 
     Next, with reference to  FIG. 13 , configurations of the cover  105  and the bottom cover  106  will be described. A left view of  FIG. 13  shows a plan view and a side view of the cover  105 , and a right view of  FIG. 13  shows a plan view and a side view of the bottom cover  106 . 
     The cover  105  has a top face formed into a substantially rectangular shape, and is formed into a box-like shape whose four sides are surrounded by side walls. Then, the housing  104  and so on described above are covered from above. At the center of the top surface of the cover  105 , a hole having a size corresponding to the size of the lens  102  is formed. 
     The bottom cover  106  is a plate-like member formed into a substantially rectangular shape, and covers the bottom face of the housing  104  and so on covered with the cover  105 . A hole having a size corresponding to the size of the lens  102  is formed at the center of the bottom cover  106 . Moreover, at each of the four corners of the bottom cover  106 , a catching part  161  that catches the other end of the abovementioned connection spring  179  is formed. Moreover, three housing parts  162  are formed on the bottom cover  106 . Each of the housing parts  162  houses the spherical support guide ball  178  in a rotatable manner, and specifies the position of the support guide ball  178 . The support guide ball  178  has a function to, while being kept sandwiched between the support guide ball receiving part  148  formed on the housing  104  and the bottom cover  106 , guide the housing  104  so as to move on a vertical plane to the direction of the optical axis of the lens  102  with respect to the bottom cover  106 . The number of the housing parts  162  is not limited to three, so that the number of the support guide balls  178  is not limited to three, either. 
     Next, with reference to  FIG. 14 , the configuration of the FPC will be described.  FIG. 14  shows a plan view and a side view of the FPC  108 . 
     The FPC  108  has a thin plate-like shape, and the outline thereof is almost the same as the bottom cover  106 . Therefore, the FPC  108  is assembled almost integrally with the bottom cover  106 , and can be treated as the same member as the bottom cover  106 . The coils  175   a  and  175   b  included by the second voice coil motors, respectively, are formed on two neighboring sides of the FPC  108 , respectively. To be specific, the coils  175   a  and  175   b  are installed opposite the magnets  174   a  and  174   b  included by the second voice coil motors installed on the housing  104 . 
     Next, with reference to  FIGS. 15 to 17 , the components for the first voice coil motors and the second voice coil motors will be described. The first voice coil motors include the magnets  171   a  and  171   b  placed on the lens barrel  103 , and the coils  172   a  and  172   b  and the yokes  173   a  and  173   b  placed on the housing  104 , respectively. 
     As shown in a front view and a plan view in the left view of  FIG. 15 , the magnets  171   a  and  171   b  included by the first voice coil motors are each formed into a rectangular shape having a predetermined thickness. Moreover, as shown in a front view and a plan view in the right view of  FIG. 15 , the coils  172   a  and  172   b  included by the first voice coil motors have outlines of almost the same sizes as the magnets  171   a  and  171   b , and are formed into oval ring-like shapes. 
     Further, as shown in a front view and a plan view in the left view and a right view of  FIG. 17 , the yokes  173   a  and  173   b  included by the first voice coil motors are formed into T-shaped thin plates, respectively, but the shapes are slightly different from each other. The first yoke  173   a  shown in the left view of  FIG. 17  is placed so as to correspond to the magnet  171   a  and the coil  172   a , and the second yoke  173   b  shown in the right view of  FIG. 17  is placed so as to correspond to the magnet  171   b  and the coil  172   b . As shown in the drawings, the second yoke  173   b  has a larger shape than the first yoke  173   a . To be specific, the leg part of the T-shaped form of the second yoke  173   b  has a larger thickness than that of the first yoke  173   a . The yokes  173   a  and  173   b  are placed so that the head parts of the T-shaped forms are placed closer to a corner at the intersection of the two neighboring sides of the lens barrel  103  where the yokes are placed. 
     Further, the second voice coil motors include the magnets  174   a  and  174   b  placed on the housing  104 , and the coils  175   a  and  175   b  installed on the bottom cover  106 , namely, on the FPC  108 , respectively. As shown in a front view and a plan view in the left view of  FIG. 16 , the magnets  174   a  and  174   b  included by the second voice coil motors are each formed into a rectangular shape having a predetermined thickness. Moreover, as shown in a front view and a plan view in the right view of  FIG. 16 , the coils  175   a  and  175   b  included by the second voice coil motors each have an outline of almost the same size as the magnets  174   a  and  174   b , and are each formed into an oval ring-like shape. 
     [Assembly] 
     Next, how to assemble the camera module  101  described above will be described with reference to  FIG. 18 . In  FIG. 18 , the camera module  101  shown in  FIGS. 10 and 20  is taken from the right side. In an assembly procedure to be described below, the order of processes may be varied. 
     First, with reference to a fourth view from the top in  FIG. 18  (the fourth view), assembly of the housing  104  and the bottom cover  106  will be described. The housing  104  and the bottom cover  106  are connected via the connection springs  179  while sandwiching the FPC  108 . To be specific, first, the four connection springs  179  are placed, respectively, in the cutout parts  147  formed on the bottom face side at the four corners of the housing  104 , and one ends of the connection springs are caught on and connected to the ceiling faces of the cutout parts  147 , respectively. Then, as shown by a dotted line arrow in the fourth view of  FIG. 18 , the other ends of the connection springs  179  are inserted into the holes formed at the four corners of the FPC  108 , and are caught by and connected to the catching parts  161  formed at the four corners of the bottom cover  106   
     Then, the support guide balls  178  are arranged in the three housing parts  162  formed on a face of the bottom cover  106  facing the housing  104 . Thus, the support guide balls  178  pass through the three through holes formed on the FPC  108  and come in contact with the housing  104  at the support guide ball receiving parts  148  formed on the bottom face of the housing  104 . Consequently, the support guide balls  178  are placed while being sandwiched between the housing  104  and the bottom cover  106 . 
     As a result that the housing  104 , the FPC  108  and the bottom cover  106  are assembled in the above manner, a force pulling the housing  104  and the bottom cover  106  to each other with the support guide balls  178  therebetween is applied by the connection springs  179 . Therefore, as shown in a third view from the top in  FIG. 18  (the third view), the housing  104  and the bottom cover  106  are integrated into one body and kept connected at a distance for the diameter of the support guide ball  178  at all times. 
     Before the assembly, the coils  175   a  and  175   b  included by the second voice coil motors are placed on the FPC  108 . In addition, the magnets  174   a  and  174   b  included by the second voice coil motors are placed opposite the coils  175   a  and  175   b  in the second concave parts  145  and  146  formed on the bottom face of the housing  104 . Consequently, driving by the stabilizer function can be realized. Moreover, the coils  172   a  and  172   b  and the yokes  173   a  and  173   b  included by the first voice coil motors are placed, respectively, in the first concave parts  143  and  144  formed on the side walls of the housing  104 . 
     Subsequently, the lens barrel  103  shown in a second view from the top in  FIG. 18  (the second view) is housed in the housing  104 . On the lens barrel  103 , the lens  102  is mounted in a lens housing hole at the center. Moreover, in the concave parts  133  and  134  formed on the side faces of the lens barrel  103 , the magnets  171   a  and  171   b  included by the first voice coil motors are placed, respectively. When the lens barrel  103  is housed into the housing  104 , the magnets  171   a  and  171   b  are placed opposite the coils  172   a  and  172   b  and the yokes  173   a  and  173   b  included by the first voice coil motors placed on the housing  104 , so that driving by the autofocus function can be realized. 
     Further, on the lens barrel  103 , the main guide ball  176  is installed in the first guide ball retaining part  131 , and the sub guide ball  177  is installed in the second guide ball retaining part  132 . Then, when the lens barrel  103  is housed into the housing  104 , the main guide ball  176  comes in contact with the first guide ball support part  141  of the housing  104  and is supported thereby, and the sub guide ball  177  comes in contact with the second guide ball support part  142  of the housing  104  and is supported thereby. 
     Meanwhile, components such as a magnet and a hole element configuring a position detection mechanism that detects the position of the lens barrel  103  along the direction of the optical axis of the lens  102  or the position of the housing  104  on a vertical plane to the optical axis direction, and other components that are not shown in the drawings may be installed during the abovementioned procedure. 
     Finally, the cover  105  shown in a first view on the top in  FIG. 18  (the first view) is placed from above so as to cover the housing  104 , whereby the assembly of the camera module  101  ends. 
     [Operation] 
     Next, an operation of the camera module  101  will be described with reference to  FIGS. 19 to 20 . First, with reference to the left view of  FIG. 19  and  FIG. 20 , driving of the lens by the autofocus function of the camera module  101  will be described. 
     The first voice coil motor that realizes the autofocus function, as shown in the left view of  FIG. 19 , includes the magnet  171   a  placed on the lens barrel  103  and magnetized so that the upper part and the lower part are an N pole and an S pole, and the coil  172   a  and the yoke  173   a  placed on the housing  104 . The yoke  173   a  is made of, for example, a soft magnetic material such as iron with few impurities, which focuses a magnetic flux generated by the magnet  171   a . Although there is one more first voice coil motor, only the first coil motor including the magnet  171   a , the coil  172   a  and the yoke  173   a  will be described hereinafter. 
     Applying electric current to the coil  172   a  causes a drive force for moving the lens barrel  103  along the direction of the optical axis of the lens  102 . To be specific, when electric current is applied to the coil  172   a , because of the direction of the electric current and a magnetic flux (see an arrow Y 1 ) passing through the coil  172   a  from the magnet  171   a , the lens barrel  103  is caused to reciprocate along the direction of the optical axis of the lens  102  (a direction of an arrow Y 21  in  FIG. 20 : the Z-axis direction) in accordance with the Fleming&#39;s left-hand rule. 
     The lens barrel  103  is equipped with the main guide ball  176  and the sub guide ball  177  that come in contact with the housing  104 , and the lens barrel  103  is kept pressed against both the guide balls  176  and  177  by the two first voice coil motors. To be specific, magnetic forces shown with arrows Y 11  and Y 12  in  FIG. 20  are caused at the two first voice coil motors, so that a resultant force Y 13  of the magnetic forces is applied to the lens barrel  103 . Thus, the lens barrel  103  keeps pressing the main guide ball  176  toward the corner along the diagonal line. 
     Further, as shown in  FIG. 20 , the magnetic forces Y 11  and Y 12  acting on the two first voice coil motors are different in strength from each other. To be specific, as shown in  FIG. 17 , the outline of the yoke  173   b  corresponding to the magnet  171   b  included by one of the first voice coil motors is larger than the outline of the yoke  173   a  corresponding to the magnet  171   a  included by the other first voice coil motor. Therefore, the magnetic force Y 12  by which the magnet  171   b  of the one first voice coil motor is attracted laterally is stronger than the magnetic force Y 11  by which the magnet  171   a  of the other is attracted laterally. Then, by a resultant force of the magnetic forces Y 11  and Y 12 , the lens barrel  103  is pressed so as to rotate about the main guide ball  176  as shown with an arrow Y 14 . As a result, the lens barrel  103  pushes the sub guide ball  177  in almost the vertical direction to the diagonal line, and the sub guide ball  177  supports the push. 
     Consequently, the lens barrel  103  keeps in contact with the housing  104  via the main guide ball  176  and the sub guide ball  177 . Then, its movement in the vertical direction to the optical axis in the housing  104  is controlled, and its posture becomes stable. As a result, it is possible to realize a stable autofocus operation without instability of the optical axis. 
     Magnetic fluxes passing through the yokes  173   a  and  173   b  from the magnets  171   a  and  171   b  are produced at the two first voice coil motors, and then, the yokes  173   a  and  173   b  each have a property of seeking to take the magnetic fluxes from the magnets  171   a  and  171   b  as much as possible. Therefore, the yokes  173   a  and  173   b  act so as to be located opposite the respective centers of the magnets  171   a  and  171   b , that is, opposite the respective boundaries of the N poles and the S poles. With such magnetic levitation, the lens barrel  103  connected with the magnets  171   a  and  171   b  levitates so that the yokes  173   a  and  173   b  are located at the respective boundaries of the N poles and the S poles of the magnets  171   a  and  171   b . Moreover, when the lens barrel  103  connected with the magnets  171   a  and  171   b  moves in accordance with the Fleming&#39;s left-hand rule and the yokes  173   a  and  173   b  are thereby dislocated upward or downward with respect to the respective centers of the magnets  171   a  and  171   b , a magnetic spring effect, which is trying to turn back to the original position with a magnetic force, arises. 
     Thus, the lens barrel  103  connected with the magnets  171   a  and  171   b  is stably located in a position corresponding to positions where the yokes  173   a  and  173   b  are installed. Therefore, by setting a position of the lens barrel  103  with magnetic levitation to a predetermined position such as a focus position, which is frequently used, it is possible to control driving of the lens barrel  103  by the first voice coil motors described above, and it is possible to achieve power saving. 
     Next, with reference to the right view of  FIG. 19  and  FIG. 20 , driving of the lens by the stabilizer function of the camera module  101  will be described. 
     The second voice coil motor that realizes the stabilizer function, as shown in the right view of  FIG. 19 , includes the magnet  174   b  magnetized so as to be an N pole and an S pole and placed on the housing  104 , and the coil  175   b  placed on the bottom cover  106 . Although there is one more second voice coil motor, only the second voice coil motor including the magnet  174   b  and the coil  175   b  will be described hereinafter. 
     Applying electric current to the coil  175   b  causes a drive force moving the housing  104  housing the lens barrel  103  along a predetermined one direction on a vertical plane to the direction of the optical axis of the lens  102 . To be specific, when electric current is applied to the coil  175   b , because of the direction of the electric current and a magnetic flux (see an arrow Y 2 ) passing through the coil  175   b  from the magnet  174   b , the housing  104  is driven to reciprocate along one linear direction on a vertical plane to the direction of the optical axis of the lens  102  (along a direction of an arrow Y 22  in  FIG. 20 : the X-axis direction) in accordance with the Fleming&#39;s left-hand rule. By the magnet  174   a  and the coil  175   a  included by the other second voice coil motor, the housing  104  is driven to reciprocate along a linear direction (the Y-axis direction) orthogonal to the abovementioned one linear direction (the X-axis direction) on the vertical plane to the optical axis direction of the lens  102 . That is, by the two second voice coil motors, the housing  104  is driven to reciprocate in the respective linear directions orthogonal to each other on the vertical plane to the optical axis direction of the lens  102 . 
     The housing  104  and the bottom cover  106  are attracted and connected to each other by the connection springs  179  with the support guide ball  178  therebetween. Thus, the housing  104  is driven by the second voice coil motors to reciprocate on the bottom cover  106  with the support guide ball  178  as a guide. In addition, the connection spring  179  has flexibility in a direction vertical to the direction of the optical axis of the lens  102 , so that the connection spring  179  bows as shown with an arrow Y 23  in  FIG. 20  at the time of driving by the second voice coil motors. However, the connection spring  179  urges the housing  104  and the bottom cover  106  to attract each other, so that the housing  104  and the bottom cover  106  keep connected at a distance for the diameter of the support guide ball  178   b  at all times. Therefore, the magnets  174   a  and  174   b  placed on the housing  104  and the coils  175   a  and  175   b  placed on the bottom cover  106  included by the second voice coil motors maintain constant distances from each other at all times. As a result, driving by the second voice coil motors become stable. 
     Further, the second voice coil motor has a structure guided by the support guide ball  178  as described above, so that the second voice coil motor has high reliability, for example, ability to avoid a fall. Moreover, the second voice coil motor having the abovementioned structure is not a spring-mass system and therefore does not have a resonance system. Also from such a viewpoint, it is possible to increase reliability. 
     The installation positions of the first voice coil motors and the installation positions of the second voice coil motors are not limited to those described above, and the first and second voice coil motors may be installed at any positions. Moreover, the shapes of the components included by the voice coil motors are not limited to those described above, and the numbers of the components may be any numbers. 
     Further, in this exemplary embodiment, as for the first voice coil motors, a case where the lens barrel  103  has the magnets  171   a  and  171   b , the housing  104  has the coils  172   a  and  172   b  and the yokes  173   a  and  173   b  has been described. However, on the contrary, the lens barrel  103  may have the coils  172   a  and  172   b  and the yokes  173   a  and  173   b , and the housing  104  may have the magnets  171   a  and  171   b . Moreover, in this exemplary embodiment, as for the second voice coil motors, a case where the housing  104  has the magnets  174   a  and  174   b  and the bottom cover  106  has the coils  175   a  and  175   b  has been described, but on the contrary, the housing  104  may have the coils  175   a  and  176   b , and the bottom cover  106  may have the magnets  174   a  and  174   b.    
     Fourth Exemplary Embodiment 
     A fourth exemplary embodiment of the present invention will be described with reference to  FIGS. 21 to 25 .  FIGS. 21 to 23  are views showing a configuration of a camera module.  FIGS. 24 and 25  are views showing an operation of the camera module. 
     The camera module according to the present invention is, for example, for taking an image, mounted on an information processing terminal such as a smartphone and a tablet terminal. However, the camera module according to the present invention is not necessarily limited to being mounted on an information processing terminal, and may be mounted on other electronic equipment or various types of equipment. 
     The camera module according to the present invention includes a lens drive unit  201  that has an autofocus function and a stabilizer function; the autofocus function automatically focuses at the time of taking an image of an object, and the stabilizer function optically compensates for camera shake occurring at the time of taking an image to reduce blur of the image. Hereinafter, a configuration of the lens drive unit  201  that realizes the autofocus function and the stabilizer function will be mainly described. Meanwhile, the lens drive unit  201  may have a function other than the functions illustrated in this exemplary embodiment. 
     First, the overall configuration of the lens drive unit  201  will be described with reference to  FIG. 21 .  FIG. 21  shows a plan view of the lens drive unit  201 . The drawings of this application show the configuration in a partially omitted manner so that its structure becomes clear. 
     First, the lens drive unit  201  includes a cover (not shown in the drawings) that covers the top and a bottom cover (not shown in the drawings) that covers the bottom. The lens drive unit  201  then includes a lens barrel  221  equipped with a lens (not shown in the drawings) and a housing  222  surrounding the lens barrel  221  to house the lens barrel  221 , inside the cover and the bottom cover that are not shown in the drawings. In addition, the lens drive unit  201  includes two first voice coil motors  243 - 245  that move the lens barrel  221  along the direction of the optical axis of the lens with respect to the housing  222 , and first guide mechanisms  241  and  242  that guide movement of the lens barrel  221  with respect to the housing  222 . Mainly, by the first voice coil motors  243 - 245  and the first guide parts  241  and  242 , the autofocus function of the lens is realized. 
     Further, the housing  222  is supported by the bottom cover (not shown in the drawings) on the bottom face side of the lens, and the lens drive unit  201  includes second voice coil motors  251  and  252  that move the housing  222  in a vertical direction to the direction of the optical axis of the lens with respect to the bottom cover. In addition, the lens drive unit  201  includes second guide mechanisms (not shown in the drawings) that are placed between the housing  222  and the bottom cover to guide movement of the housing  222  with respect to the second voice coil motors  251  and  252 , and connection springs (not shown in the drawings) that connect the housing  222  to the bottom cover. Mainly by these components, the lens stabilizer function is realized. 
     Further, the lens drive unit  201  includes a FPC (Flexible Printed Circuit) and other components. Hereafter, the respective components will be described. 
     As shown in  FIG. 21 , the lens barrel  221  has a substantially rectangular outline. At the center of the lens barrel  221 , a lens housing hole that houses the lens is formed. 
     Next, the first voice motors that realize the lens autofocus function will be described. Of the side faces of the lens barrel  221 , in the vicinity of two neighboring sides of the substantially rectangular outline, magnets  243   a  and  243   b  configuring the first voice coil motors are placed, respectively. Moreover, coils  244   a  and  244   b  and yokes  245   a  and  245   b  configuring the first voice coil motors are placed on the housing  222  so as to be opposite the magnets  243   a  and  243   b , respectively. Thus, the first voice coil motors that realize the autofocus function are placed at places corresponding to the two neighboring sides of the substantially rectangular outline. 
     Further, a main guide part is formed at a position corresponding to a corner sandwiched by the two neighboring sides with the two first voice coil motors  243 - 245  placed of the substantially rectangular lens barrel  221 . To be specific, a first guide ball retaining part configuring the main guide part is formed at the corner of the lens barrel  221  sandwiched by the abovementioned two first voice coil motors  243 - 245 . The first guide ball retaining part is formed by a groove along the direction of the optical axis of the lens, and the groove is open outward on a diagonal line passing through the corner where the groove is formed. Then, the first guide ball retaining part retains a spherical main guide ball  241  configuring the main guide part, in a rotatable manner. The main guide ball  241  is pressed against and supported by a first guide ball support part to be described later, which is formed on the inner face of the housing  222 , configures the main guide part and has a concave shape. Consequently, the main guide ball  241  rotates in the groove serving as the first guide ball retaining part and, with this, the lens barrel  221  is guided by the main guide ball  241  to move along the direction of the optical axis of the lens. Herein, any number of main guide balls  241  may be retained. 
     Further, on the lens barrel  221 , a sub guide part is formed at the other corner located diagonally to the corner where the first guide ball retaining part is formed. To be specific, at the abovementioned corner of the lens barrel  221 , a retaining mechanism  261  and a sub guide ball  242  configuring the sub guide part are placed. The retaining mechanism  261  is connected to the abovementioned corner on the outer perimeter of the lens barrel  221  and is formed so as to extend from that corner toward a corner inside the housing  222 . To be specific, as shown in  FIGS. 22 and 23 , the retaining mechanism  261  includes a base part  261   a  and a retaining part  261   b ; the base part  261   a  is connected to the outer perimeter of the lens barrel  221 , and the retaining part  261   b  extends from the base part  261   a  and is made of two joist members located in parallel along the direction of the optical axis of the lens. The retaining part  261   b  retains the sub guide ball  242  between the two joist members. In this case, a retaining face of the retaining part  261   b , located between the two joist members, is formed into a concave shape as shown in  FIG. 23 , and retains the sub guide ball  242  contacting at a point or a little area. The two joist members of the retaining part  261   b  retain the sub guide ball  242  so that the sub guide ball  242  can rotate and move in the direction of the optical axis and can also move along a longitudinal direction of the two joist members. 
     At a corner position of the housing  222 , opposite the corner position of the lens barrel  221  where the retaining mechanism  261  and the sub guide ball  242  are placed, a concave part  263  configuring a sub guide part to house the retaining part  261   b  and the sub guide ball  242  is formed. To be specific, the concave part  263  is formed like a groove along the lens optical axis direction at the corner position inside of the housing  222 . An opening  264  of the concave  263  is formed so as to have a smaller cross-sectional area than an inner space of the concave  263 . Consequently, as shown in  FIG. 22 , a tip of the retaining part  261   b  can be inserted into the concave  263 , but the sub guide ball  242  retained inside the retaining part  261   b  is caught in the concave  263  by the opening  264  formed narrow and is prevented from protruding outside from inside the concave  263 . 
     Further, as shown in  FIGS. 22 and 23 , on the base part  261   a  of the retaining mechanism  261 , a magnet  262  is placed. That is, the magnet  262  is not inserted into the concave  263  formed on the housing  222 , and is placed on the base part  261   a  that is located closer to the lens barrel than the concave  263  and in the vicinity of the root of the retaining part  261   b . Thus, the sub guide ball  242  is made of a magnetic material such as iron attracted by a magnet. Consequently, in the sub guide part  242 , the sub guide ball  242  housed in the housing  222  by the retaining mechanism  261  keeps attracted toward the lens barrel at all times and remains in contact with the inside wall near the opening of the concave  263 . In this case, the sub guide ball  242  is retained so as to rotate along the lens optical axis direction in the concave  263 , so that the lens barrel  221  can move along the lens optical axis direction. 
     As described above, the first voice coil motors  243 - 245  that realize the autofocus function in this exemplary embodiment are placed on the two neighboring sides of the substantially rectangular lens barrel  221 , respectively, and the magnets  243   a  and  243   b  are magnetically attracted to the yokes  245   a  and  245   b , respectively. That is, the two first voice coil motors  243 - 245  cause magnetic forces shown in  FIG. 24 , and a resultant force thereof is applied to the lens barrel  221 . Therefore, a force that the lens barrel  221  presses the main guide ball  241  diagonally toward the corner is applied. 
     In this case, the sub guide ball  242  located on the corner diagonally opposite the main guide ball  241  is caught in the concave  263  by the opening  264  and, as shown in  FIG. 24 , is diagonally attracted by the magnet  262  toward the main guide ball  241 . In addition, the retaining mechanism  261  equipped with the magnet  262  is integrated with the lens barrel  221 , so that it is attracted toward the main guide ball  241 . Therefore, a force that the lens barrel  221  pulls the housing  222  toward the main guide ball  241  via the mechanism of the sub guide part including the sub guide ball  242  and so on is applied. 
     The lens barrel  221  is in contact with the housing  222  with no space via the main guide ball  241  and the sub guide ball  242 , so that it can inhibit occurrence of rattling. Thus, movement in the vertical direction to the optical axis in the housing  222  is controlled and the posture becomes stable. As a result, it is possible to realize a stable autofocus function without instability of the optical axis. 
     The magnet  243   a  of the first voice coil motor  243 - 245  is magnetized so that the upper part and the lower part are an N pole and an S pole on the side of the lens barrel  221  as shown in the left view of  FIG. 25 . Applying electric current to the coil  244   a  in such a configuration causes a drive force for moving the lens barrel  221  along the lens optical axis direction. To be specific, when electric current is applied to the coil  244   a , because of the direction of the electric current and a magnetic flux passing through the coil  244   a  from the magnet  243   a , the lens barrel is caused to reciprocate along the lens optical axis direction (the Z-axis direction) in accordance with the Fleming&#39;s left-hand rule. Consequently, the autofocus function can be realized. 
     Next, the second voice coil motors  251  and  252 , which are configurations realizing the lens stabilizer function, will be described. The second voice coil motors include the two voice coil motors  251  and  252  and allow for movement of the housing  222  itself that houses the lens barrel  221  with respect to the bottom cover. In this case, as shown in  FIG. 21 , the two voice coil motors  251  and  252  are placed, respectively, near two neighboring sides that are different from the two sides where the first voice coil motors  243 - 245  are placed of the four sides forming the outer perimeter of the substantially rectangular lens derive unit  201 . That is, the two voice coil motors  251  and  252  are placed, respectively, near the two sides orthogonal to each other. 
     One voice coil motor  251  is installed in the vicinity of a side located on the upper side in  FIG. 21 , and moves the housing  222  in the vertical direction. The other voice coil motor  252  is installed in the vicinity of a side located on the right side in  FIG. 21 , and moves the housing  222  in the horizontal direction. Thus, the two voice coil motors  251  and  252  can move in two linear directions orthogonal to each other on a vertical place to the lens optical axis direction. 
     To be specific, one of the voice coil motors includes the magnet  251  placed on the lower face of the housing  222  and a coil (not shown in the drawings) installed on the bottom cover so as to correspond to the magnet  251 . Likewise, the other voice coil motor includes, as shown in the right view of  FIG. 25 , the magnet  252  placed on the lower face of the housing  222  and a coil  252   b  installed on the bottom cover so as to correspond to the magnet  252 . Then, the one voice coil motor including the magnet denoted by reference numeral  251  shown in  FIG. 21  allows movement along one linear direction (Y-axis direction) on the vertical plane to the lens optical axis direction when electric current is applied to the coil (not shown in the drawings) corresponding to the magnet  251 . Moreover, the other voice coil motor including the magnet denoted by reference numeral  252  allows movement along the other linear direction (X-axis direction) that is orthogonal to the one linear direction on the vertical plane to the lens optical axis direction when electric current is applied to the coil  252   b  corresponding to the magnet  252 . 
     Thus, the lens drive unit  201  according to the present invention can realize movement in the lens optical axis direction with the first voice coil motors  243 - 245 , and can realize movement in the vertical direction to the lens optical axis direction with the second voice coil motors  251  and  252 . Then, it is possible to prevent the lens barrel from rattling by magnetic forces generated by the first voice coil motors  243 - 245 , and it is possible to realize a stable autofocus function without instability of the optical axis. 
     Meanwhile, in the lens drive unit  201  in this exemplary embodiment, the second voice coil motors  251  and  252  are illustrated as a configuration for realizing movement in the vertical direction to the lens optical axis direction, but the configuration for realizing movement in the vertical direction may be any configuration. 
     Fifth Exemplary Embodiment 
     Next, a fifth exemplary embodiment of the present invention will be described with reference to  FIGS. 26 to 27 . A camera module according to the present invention is a dual camera including two cameras. Therefore, the camera module includes two lens drive units described in the exemplary embodiment 4 (denoted by reference numerals  201 A and  201 B). 
     In configuring the dual camera with the two lens drive units  201 A and  201 B, the lens drive units  201 A and  201 B are arranged adjacent to each other. For example, the lens drive units  201 A and  201 B are formed so as to have substantially square outlines and are arranged so that one sides of the outer peripheries are in parallel and adjacent to each other. The outlines of the lens drive units  201 A and  201 B are not limited to a square, and may be formed so as to be substantially rectangular. 
     In this exemplary embodiment, the abovementioned two lens drive units  201 A and  201 B configuring the dual camera are arranged as shown in  FIG. 26 or 27 . In  FIGS. 26 and 27 , only the magnets  251  and  252  of the second voice coil motors  251  and  252  that are components for realizing the lens stabilizer function described in the fourth exemplary embodiment are illustrated as the components of the lens drive units  201 A and  201 B. That is, the arrangement of the magnets  251  and  252  of the second voice coil motors is important. 
     The two voice coil motors  251  and  252  are arranged, respectively, in the vicinity of two neighboring sides of the four sides forming the outer perimeter of the substantially rectangular lens drive unit  201 A as described above. In this exemplary embodiment, it is desirable to arrange the magnets  251  and  252  configuring the two voice coil motors so as not to be located on sides where the lens drive units  201 A and  201 B are located adjacent to each other. 
     To be specific, in an example shown in the upper view of  FIG. 26 , one lens drive unit  201 A located on the left is placed so that the magnets  251  and  252  are located in the vicinity of the left side and in the vicinity of the upper side of the outer perimeter, and the other lens drive unit  201 B located on the right is placed so that the magnets  251  and  252  are located on the right side and the lower side. Thus, the lens drive units  201 A and  201 B are arranged so that the magnets  251  and  252  configuring the stabilizer functions of the lens drive units  201 A and  201 B are located so as to be point-symmetric with respect to the vicinity of the midpoints of the sides where the lens drive units are located adjacent to each other. Consequently, none of the magnets  251  and  252  are located in positions where the lens drive units  201 A and  201 B are adjacent to each other, so that magnetic interference can be inhibited. 
     Further, in an example shown in the lower view of  FIG. 26 , one lens drive unit  201 A located on the left is placed so that the magnets  251  and  252  are located in the vicinity of the left side and in the vicinity of the upper side of the outer perimeter, and the other lens drive unit  201 B located on the right is placed so that the magnets  251  and  252  are located in the vicinity of the upper side and in the vicinity of the right side. Thus, the lens drive units  201 A and  201 B are arranged so that the magnets  251  and  252  configuring the stabilizer functions of the lens drive units  201 A and  201 B are located so as to be line-symmetric with respect to sides where the lens drive units  201 A and  201 B are located adjacent to each other. Consequently, none of the magnets  251  and  252  are located in positions where the lens drive units  201 A and  201 B are adjacent to each other, so that magnetic interference can be inhibited. 
     Further, in this exemplary embodiment, the abovementioned two lens drive units  201 A and  201 B configuring the dual camera may be installed so that none of the magnets  251  and  252  configuring the voice coil motors are not located on one of sides where the lens drive units  201 A and  201 B are located adjacent to each other. 
     To be specific, in an example shown in the upper view of  FIG. 27 , one lens drive unit  201 A located on the left is placed so that the magnets  251  and  252  are located in the vicinity of the left side and in the vicinity of the upper side of the outer perimeter, and the other lens drive unit  201 B located on the right is placed so that the magnets  251  and  252  are located in the vicinity of the lower side and in the vicinity of the left side. Thus, even if the magnet  252  of the lens drive unit  201 B is located between the lens drive units  201 A and  201 B, magnetic interference can be inhibited. 
     Further, in an example shown in the lower view of  FIG. 27 , one lens drive unit  201 A located on the left is placed so that the magnets  251  and  252  are located in the vicinity of the left side and in the vicinity of the upper side on the outer perimeter, and the other lens drive unit  201 B located on the right is placed so that the magnets  251  and  252  are located in the vicinity of the left side and in the vicinity of the upper side. Thus, even if the magnet  252  of the lens drive unit  201 B is located between the lens drive units  201 A and  201 B, magnetic interference can be inhibited. 
     Meanwhile, examples shown in the upper and lower views of  FIG. 28  are examples for comparison with the configurations in this exemplary embodiment shown in  FIGS. 26 and 27 . As shown in the upper and lower views of  FIG. 28 , in a case where the magnets  251  and  252  configuring the stabilizer functions of the lens drive units  201 A and  201 B are located on the sides where the lens drive units  201 A and  201 B are located adjacent to each other, the magnets  251  and  252  may cause magnetic interference. Therefore, the arrangements shown in  FIGS. 26 and 27  are desirable. 
     Herein, on the sides where the lens drive units  201 A and  201 B are located adjacent to each other, at least one of the magnets  243   a  and  243   b  of the first voice coil motors for realizing the autofocus function is located. In other words, the magnets  243   a  and  243   b  of the first voice coil motors are located adjacent to each other in the example shown in  FIG. 26 , and one magnet ( 243   a  or  243   b ) of the first voice coil motor and one magnet ( 251  or  252 ) of the second voice coil motor are adjacent to each other in the example shown in  FIG. 27 . However, the first voice coil motors for autofocus include the yokes  24   a  and  245   b  outside the magnets  243   a  and  243   b . Therefore, magnetic interference between the magnets adjacent to each other can be inhibited. 
     As described above, according to the camera module of the present invention shown in  FIGS. 26 and 27 , the voice coil motors for realizing the stabilizer functions of the lens drive units configuring the dual camera are not placed adjacent to each other, so that magnetic interference can be inhibited. As a result, it is possible to prevent decrease of the stabilizer function of the lens drive unit. 
     Although the present invention has been described above with reference to the exemplary embodiments and so on, the present invention is not limited to the exemplary embodiments. The configurations and details of the present invention can be altered and changed in various manners that can be understood by one skilled in the art within the scope of the present invention.