Abstract:
The present invention aims to provide a lens drive unit installation structure which enhances dust resistance to improve reliability and realizes miniaturization and easiness to assemble. For achieving the purposes, the lens drive unit installation structure for installing a lens drive unit including: a lens holding frame for holding a lens, and a lens moving mechanism for slidingly move the lens holding frame in the direction of an optical axis using a drive source, wherein the drive source to be linked with the lens moving mechanism is arranged on the side of the lens holding frame view from the direction of the optical axis, and a partition is set between the lens holding frame and the drive source, thereby the lens and the drive source are arranged separately from each other.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a lens drive unit including a lens holding frame for holding a lens and a lens moving mechanism for slidingly move the lens holding frame using a drive source, and in particular to a installing structure thereof. 
         [0003]    2. Description of the Related Art 
         [0004]    For optical zooming system of an imaging device, a system in which a plurality of lens groups (a zooming lens group, a focus lens group) is provided, and the system in which these lens groups are made to move in the direction of an optical axis to zoom and focus. A lens drive unit provide the lens holding frame which is holding a lens along the optical axis are arranged in series so as to be able to slide in the optical axis direction, and it make a lens holding frame to slide by a drive source. For the drive source to slidingly move the lens group holding frame, a motor is widely used. Then, it controlling precisely positions of the lens groups by a mechanism which is provided that detects a position of the lens group holding frame by using detection means and controls the motor in response to the position of the lens group holding frame. 
         [0005]    For example, Japanese Patent Application Publication No. 2004-133054 discloses a lens barrel in which include a second group lens as a zoom lens are held by a second group frame and a third group lens as a focus lens are held by a third group frame, then a first step motor for driving the second group frame to move in front-back direction and a second step motor for driving the third group frame to move in front-back direction are fixed to a inside of a left side wall as a first outer wall of a fixed frame at the left side of each frames. The lens barrel includes detection means for detecting a position of the holding frame, and a motor terminal provided in a motor unit and the detection means are connected to a flexible printed circuit board and controlled. A lens drive unit disclosed in Japanese Patent Application Publication No. 2004-133054, for the purposes of miniaturization and a simplified structure, has a drive mechanism and the lens groups arranged adjacent to each other. 
         [0006]    In the conventional technology described above, dust may unavoidably come into the inside of a lens barrel. Dust is likely to gather particularly to a motor because it generates heat due to its operation, and when a drive mechanism and a lens group are, as disclosed in Japanese Patent Application Publication No. 2004-133054, arranged adjacent to each other, dust is also likely to gather to the lens group in conjunction with motor operation. As a result, dust may affect imaging performance due to its attachment to a lens or cause a malfunction of a lens group holding frame due to its attachment to the drive mechanism, thus possibly causing adverse effect. 
         [0007]    Concerning this point, in the case of a collapsible lens barrel, there is an example in which a foreign substance removal mechanism is provided at a gap or inside of the lens barrel which is likely to through enter dirt or dust. The collapsible lens barrel, for example, an image pickup device disclosed in Japanese Patent Application Publication No. 2006-251197, includes an outer tube and an inner tube which situate inside of a fixed cylinder and slide back and forth from a front end of the fixed cylinder in the direction of an optical axis, and the outer tube hold an auto focus lens group and the inner tube hold a zoom lens group. Then, for zooming and focusing, drive force of a drive motor is transmitted to a gear to slide the outer tube and the inner tube in the direction of an optical axis, thus making a small gap lead from the outside. To prevent a foreign substance from entering into the inside of the lens barrel through the gap in this sliding portion, an adhesive layer is provided in the gap portion to cause the foreign substance to adhere thereto. 
         [0008]    However, a non-collapsible lens barrel according to Japanese Patent Application Publication No. 2004-133054, compared with a collapsible lens barrel, has an advantage that a mechanism thereof can be miniaturized. Besides, a mechanism of a lens drive unit is getting complicatedly to set detection means and control means are provided to control a position of a lens group holding frame, and accordingly, it has been a challenge on how to lay out a component for the purpose of miniaturization, and when a foreign substance removal mechanism is further added, it is difficult to lay out a small lens barrel. 
         [0009]    Therefore, an object of the present invention is to provide a lens drive unit installation structure which enhances keeping out dust to improve reliability and realizes miniaturization and easiness to assemble. 
       SUMMARY OF THE INVENTION 
       [0010]    The inventor, as the result of intense study, has achieved the object described above by adopting a lens drive unit installation structure and a lens drive unit described below. 
         [0011]    A lens drive unit installation structure for installing a lens drive unit including: a lens holding frame for holding a lens, and a lens moving mechanism for slidingly move the lens holding frame in the direction of an optical axis using a drive source, wherein the drive source to be linked with the lens moving mechanism is arranged on the side of the lens holding frame view from the direction of the optical axis, and a partition is set between the lens holding frame and the drive source, thereby the lens and the drive source are arranged separately from each other. 
         [0012]    A lens drive unit installation structure for installing a lens drive unit including: a lens holding frame for holding a lens, and a lens moving mechanism for slidingly move the lens holding frame in the direction of an optical axis using a drive source, wherein the lens moving mechanism and the drive source to be linked with it are arranged on the side of the lens holding frame view from the direction of the optical axis, and a partition is set between the lens moving mechanism and the drive source, thereby the lens and the drive source are arranged separately from each other. 
         [0013]    In a lens drive unit installation structure according to the present invention, more preferably, a lens holding frame are housed in the lens housing, the partition is a part of the lens housing. 
         [0014]    In a lens drive unit installation structure according to the present invention, more preferably, a motor as the drive source is arranged outside of and adjacent to the partition, a window for pass through an output shaft is formed in the partition, and a bearing for an output shaft of the motor is put into the window by insertion, thereby the motor is positioned to the partition. 
         [0015]    In a lens drive unit installation structure according to the present invention, more preferably, a lens holding frame and the lens moving mechanism are housed in the lens housing, a motor as the drive source is arranged outside of and adjacent to the lens housing, a window for pass through an output shaft is formed in a wall of the lens housing on the side where the motor is arranged, and the motor is arranged separately in a state that drive transmission means provided in the lens moving mechanism for transmitting drive force of the motor to the lens holding frame and the motor are connected to each other at the output shaft window. 
         [0016]    In a lens drive unit installation structure according to the present invention, more preferably, a drive source fixing boss to fix the motor is formed in the partition. 
         [0017]    A lens drive unit installation structure according to the present invention, more preferably, a window for a position detection sensor is formed in the partition to arrange the position detection sensor detecting a displacement position of the lens holding frame. 
         [0018]    A lens drive unit installation structure according to the present invention, more preferably, a mechanical stopper mounting portion provided on the partition to set a mechanical stopper which restrict a displacement range of the lens group holding frame. 
         [0019]    A lens drive unit according to the present invention has a feature of being assembled using the lens drive unit installation structure described above. 
         [0020]    The lens drive unit installation structure according to the present invention houses a lens holding frame and a drive source separately from each other to prevent dust or dirt from entering into the inside of a lens housing, thus being able to prevent the dust or dirt from adhering to a lens and a moving mechanism for the lens group holding frame. As a result, a highly reliable lens drive unit can be provided. Further, a partition is used to both position other components and form a fixing frame, besides providing a dust prevention effect, thus being able to enhance accuracy in linking components of the lens drive unit with each other. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a plan view showing an embodiment of a lens drive unit using a lens drive unit installation structure according to the present invention; 
           [0022]      FIG. 2  is a perspective view of the lens drive unit shown in  FIG. 1 ; 
           [0023]      FIG. 3  is a perspective view showing a housing of the lens drive unit shown in  FIG. 1 ; 
           [0024]      FIG. 4  is a side view of the housing shown in  FIG. 3 , seen from a third wall; 
           [0025]      FIG. 5  is an exploded perspective view of the lens drive unit shown in  FIG. 1  on the side of the third wall; 
           [0026]      FIG. 6  is a perspective view of the lens drive unit shown in  FIG. 1 , seen from the third wall; and 
           [0027]      FIG. 7  is a cross-sectional view taken along the line A-A′ in the lens drive unit shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    Now, best modes of a lens drive unit installation structure according to the present invention will be described with reference to the accompanying drawings. Note that the present invention should not be limited to illustrated embodiments. 
         [0029]    A lens drive unit installation structure according to the present invention is the structure for installing a lens drive unit including: a lens holding frame for holding a lens, and a lens moving mechanism for slidingly move the lens holding frame using a drive source.  FIG. 1  is a top view showing an embodiment of the lens drive unit according to the present invention, and  FIG. 2  is a perspective view of the lens drive unit shown in  FIG. 1 . The lens drive unit  1  shown in  FIG. 1  and  FIG. 2  includes a lens moving mechanism and motors  31 ,  32  as a drive source for the lens moving mechanism. The lens drive unit  1  according to the present embodiment make a first lens group holding frame  41  and a second lens group holding frame  42  to slide by using a first motor  31  and a second motor  32  independently and respectively along an optical axis L of lens. 
         [0030]    A lens moving mechanism  2  is the structure mainly composed of lens group holding frames  41 ,  42 , guide poles  51 ,  52 , guide portions  61 ,  62  and drive transmission means (racks  71 ,  72 , pinions  81 ,  82 ), for slidingly move the lens group holding frames  41 ,  42 . The lens moving mechanism  2  holds lens groups for an image pickup device in two lens group holding frames (first lens group holding frame  41 , second lens group holding frame  42 ), respectively. 
         [0031]    The lens group for an image pickup device is the group in which a plurality of lenses is combined with each other and set with their optical axes being aligned with an optical axis L, and, for example, the group is used as a focus lens or a zoom lens. The lens group holding frames  41 ,  42  hold the lens group so that the lens group is inserted thereinto to fix, and optical axes are aligned with an optical axis of a fixed lens provided in a lens barrel. Accordingly, the lens group holding frame holding a zoom lens or a focus lens is moved in the direction of the optical axis L of the lens, thereby an optical zoom function and an optical focus function can be performed. 
         [0032]    In the lens moving mechanism  2  according to the present embodiment, two guide poles are arranged parallel to the optical axis L on outer edges of the lens group holding frames  41 ,  42 . The lens group holding frames  41 ,  42  are latched on the guide poles  51 ,  52 , thus being supported while restricting the direction in which the lens group holding frames  41 ,  42  are moved. 
         [0033]    The first lens group holding frame  41  and the second lens group holding frame  42  are linked with a first guide member  61  and a second guide member  62  on the outer edges of the lens group holding frames  41 ,  42 , respectively. The guide members  61 ,  62  form a tubular shape having a sleeve into which the guide pole  51  or  52  can be inserted, and the guide poles  51 ,  52  are inserted into the sleeves, respectively, thereby the lens group holding frames  41 ,  42  are supported by the guide poles  51 ,  52  in a slidable manner. 
         [0034]    Further, the lens group holding frames  41 ,  42  are supported by an auxiliary guide pole  53  in a slidable manner, besides the guide poles  51 ,  52 , which can prevent minute deviation of the optical axis of the lens caused by sliding movement. In this case, auxiliary holding portions  411 ,  421  are provided to latch the auxiliary guide pole  53  on the outer edges of the lens group holding frames  41 ,  42 . 
         [0035]    Drive transmission means transmits movement from the drive source to the lens group holding frames  41 ,  42  as linear movement in the direction of sliding movement along the optical axis L. In this embodiment, the drive transmission means has adopted pinions  81 ,  82  provided on output shafts  31   b ,  32   b  of the motors  31 ,  32  as the drive source, and racks  71 ,  72  formed on the side of the lens group holding frames  41 ,  42 . That is, the pinions  81 ,  82  are mounted on rotating output shafts  31   b ,  32   b  of the motors  31 ,  32 , respectively, and the racks  71 ,  72  are mounted on the side of the lens group holding frames  41 ,  42 , respectively. The pinions  81 ,  82  are provide to gear with the racks  71 ,  72 , respectively, which converts rotating movement of the motors  31 ,  32  into linear movement in the direction in which the lens group holding frames  41 ,  42  are slidingly moved, thus being transmitted. 
         [0036]    The motors  31 ,  32  are used as drive means to slidingly move the lens group holding frame. The motors  31 ,  32  used are desirably a flat motor having a thin thickness in the direction of the output shaft. In the lens drive unit according to the present invention, the motors  31 ,  32  (drive source) are arranged on the side of the lens group holding frames in the direction of the optical axis. Then, in the embodiment, the output shafts  31   b ,  32   b  of the motors  31 ,  32  are set in the direction perpendicular to the direction in which the lens group holding frames are slidingly moved (optical axis L). Accordingly, use of the flat motor allows the length of the motors  31 ,  32  in the direction of the output shafts  31   b ,  32   b  to be made short, which can miniaturize the lens drive unit, thus being suitable for miniaturizing the lens barrel in the width direction. 
         [0037]    In the lens drive unit installation structure according to the present invention, the drive source to be linked with the lens moving mechanism is arranged on the side of the lens holding frame view from the direction of the optical axis. Then, the lens drive unit installation structure offers a feature that a partition is provided between the lens group holding frame and the drive source, and a region for setting the lens holding frames is used as a lens housing, thus the lens and the drive source are arranged separately from each other. 
         [0038]    Further, in the lens drive unit installation structure according to the present invention, the lens moving mechanism and the drive source to be linked with it may be arranged on the side of the lens holding frame view from the direction of the optical axis. Then, the lens drive unit installation structure offers a feature that a partition is provided between the lens moving mechanism and the drive source, thus the lens and the drive source are arranged separately from each other. A method for positioning separately, in this embodiment, is shown as the method that, using a housing  9  shown in  FIG. 3 , the lens moving mechanism  2  is housed in a lens housing  9 S, the motors  31 ,  32  as the drive source are arranged outside of and adjacent to the lens housing  9 S, thus housing the lens moving mechanism  2  and the motors  31 ,  32  so that they are separated from each other. 
         [0039]    A housing  9 , as shown in  FIG. 3 , has an approximately rectangular parallelepiped shape and is formed by drilling, machining or the like of a molded body made of a resin or metal. The housing  9  includes the lens housing  9 S for housing the lens moving mechanism  2  and a prism housing part  92  for housing a prism  10  for refracting a light flux from an object, in series along the optical axis L. 
         [0040]    The lens housing  9 S is composed of a first wall  93  on the side of an object, a second wall  94  on the side of an image plane, a third wall  91  and a fourth wall  95  providing side walls, and a base  96 . In the present embodiment, on the side of the lens drive unit in the direction of the optical axis, the motors  31 ,  32  are arranged side-by-side with the third wall  91  (partition) there between. In other ward, the third wall  91  is a partition which is separated between a lens driving mechanism and a driving resource. 
         [0041]    Note that the lens housing  9 S may be able to house the lens and connect the motors  31 ,  32  to the drive transmission means with the partition there between, and the lens housing  9 S may have, not limited to the approximately rectangular parallelepiped shape as shown in  FIG. 3 , a tubular shape or a special shape fitting an outline of the lens moving mechanism  2 . Also, to reduce size and weight of the lens drive unit, various mechanisms of the drive transmission means and the like are preferably centralized and disposed on the side of the lens group holding frame. Then, the partition more preferably combines a dust prevention function with a function of mounting various mechanisms of the lens drive unit and positioning them. In this case, a wall surface (third wall  91 ) on the side of the lens housing  9 S of the lens group holding frame view from the direction of the optical axis L is used as the partition between the lens moving mechanism  2  and the motors  31 ,  32 . Then, at least a portion of the partition used to mount and/or position the various mechanisms of the lens drive unit is preferably formed so as to be approximately planar at a position where the portion is parallel to the optical axis. This can eliminate inefficiency from a layout of the lens drive unit, make it easier to form and machine the housing  9 S, facilitate positioning and/or mounting the various mechanisms in production, and also improve accuracy of the position detection function of the lens group holding frame. 
         [0042]    On the first wall  93 , a prism housing part  92  is arranged adjacent to it, and a holding window for holding an end of the lens moving mechanism  2  is formed. On the holding windows, the prism  10  and the end of the lens moving mechanism  2  on the side of the first lens group holding frame  41  are placed, respectively. The prism housing part  92  is fixed, while housing the prism  10 , by machine screws  921  from outside of the first wall  93  of the housing  9 S. 
         [0043]    In the second wall  94 , a fixed lens insertion hole is formed, into which a fixed lens fixedly positioned on the second lens group holding frame  42  on the side of an image plane is inserted, and on the nearer side of the image plane from the fixed lens insertion hole, a fixed lens housing  97  is formed. 
         [0044]    The third wall  91  provides a wall for separating the lens moving mechanism  2  from the motors  31 ,  32 . Also, in the third wall  91 , a plurality of windows is formed.  FIG. 4  is a plan view showing the housing  9 , seen from the third wall  91 . In the third wall  91 , as windows, output shaft windows  911  into which the output shafts  31   b ,  32   b  of the motors  31 ,  32  are inserted, respectively, motor fixing bosses  912  for fixing the motors  31 ,  32 , position detection sensor windows  913 , and mechanical stopper mounting portions  914  where a groove for latching a mechanical stopper  24  is formed. 
         [0045]    The output shaft window  911  is the through hole used to connect drive force transmission means for transmitting drive force of the motors  31 ,  32  to the lens moving mechanism  2 , to the output shafts  31   b ,  32   b  of the motor, and in the output shaft window  911 , the output shafts  31   b ,  32   b  of the motor and the drive force transmission means are connected to each other. 
         [0046]    The motor fixing bosses  912  are the openings having a bottom and formed on the side of the outer surface of the third wall  91  so as to correspond to installation positions of the motors  31 ,  32 , respectively. The motor fixing bosses  912  can both position the motors  31 ,  32  and fix them directly on the lens housing  9 S. Accordingly, through the lens housing  9 S, the lens moving mechanism  2  and the motors  31 ,  32  are connected to each other, which, besides providing dust prevention, can allow the motors  31 ,  32  to be installed without affecting a layout of components of the lens moving mechanism  2 . The position detection sensor window  913  and the mechanical stopper mounting portion  914  will be described hereinafter. 
         [0047]    Further, the output shaft windows  911  can also position the installation positions of the motors  31 ,  32 . That is, windows for output shaft fitting a shape of bearings (not shown) provided on the output shafts  31   b ,  32   b  of the motors  31 ,  32  may be formed correspondingly to the installation positions of the motors  31 ,  32 , and the bearings of the output shafts  31   b ,  32   b  of the motors  31 ,  32  are inserted into the output shaft windows  911 , respectively, which positions the motors  31 ,  32  on the third wall surface  91 . 
         [0048]    In the fourth wall  95 , to dispose a flexible printed circuit board (hereinafter, it may be called “FPC”) across the outside and the inside of the housing  9 , FPC slits  951  are formed. 
         [0049]    In addition, in the walls  91 ,  93 ,  94 ,  95  of the lens housing  9 S, besides the above, windows into which various members are inserted to fix, or slits in which various members relating to the lens moving mechanism  2  are disposed may be optionally formed. Further, a position, shape, size and the like of the opening or the slit may be appropriately set dependent on design of the lens drive unit. However, to enhance dust resistance, the size of the opening or the slit is set dependently on that of a component to be disposed thereon, thus eliminating an unnecessary gap. 
         [0050]    Now, a method for assembling the lens drive unit  1  will be described. First, the lens moving mechanism  2  is arranged in the lens housing  9 S. Note that the perspective view of the housing  9  shown in  FIG. 3  shows, for the illustrative purpose, a state in that the prism housing part  92  is installed in the lens housing  9 S, and procedures of mounting are: the lens moving mechanism  2  is arranged in the lens housing  9 S; and then the prism housing part  92  in which the prism  10  is arranged is fixed in the lens housing  9 S by the machine screws  912 . 
         [0051]    First, the fixed lenses connected to each other in the second lens group holding frame  42  on the side of the image plane are inserted into the fixed lens insertion hole of the lens housing  9 S to fit therein, and concurrently, the guide poles  51 ,  52  and the auxiliary guide pole  53  are inserted into guide pole insertion holes, respectively. After the fixed lenses and the guide poles are inserted to be arranged, the lens moving mechanism  2  is pushed into in the direction of the optical axis L to force the end of the first lens group holding frame  41  to abut on the holding window of the first wall  93 . Next, a prism unit including the prism  10  is arranged in the prism housing part  92 , and forced to abut on the first wall  93  of the lens housing  9 S. Subsequently, the lens moving mechanism  2  is slightly pulled back to the first wall  93 , and the other ends of the guide poles  51 ,  52  and the auxiliary guide pole  53  are inserted into guide pole insertion holes formed in the first wall  93 , thus installing the lens moving mechanism  2  in the lens housing  9 S. Next, the lens moving mechanism  2  is fixed on the first wall  93  by the machine screws  921 . In this state, the prism  10  and the lens group included in the lens moving mechanism  2  are positioned so that their optical axes are aligned with each other. 
         [0052]    Next, the mechanical stoppers  24 , reflection sensors  21 , the motors  31 ,  32  are arranged.  FIG. 5  is an exploded perspective view of the lens drive unit shown in  FIG. 1 , on the side of the third wall. Outside of the housing  9  on the side of the third wall  91 , the motors  31 ,  32  are arranged and fixed. Further, between the third wall  91  and the motors  31 ,  32 , the reflection sensors  21  and mechanical stoppers  24  are arranged. 
         [0053]    The lens drive unit  1  includes, besides the lens moving mechanism  2  and the motors  31 ,  32 , position detection means  20 . The position detection means is composed of reflection patterns (not shown), reflection sensors  21  (position detection sensor) and a sensor board (not shown), and detects positions of the lens group holding frames  41 ,  42 . The reflection patterns are provided on the side of the lens group holding frames  41 ,  42 . The reflection sensor  21  is arranged in a position detection sensor window  913  formed on the third wall  91  of the housing  9  at a position facing the reflection pattern, and the sensor board connected to the reflection sensor  21  is arranged outside of the lens housing  9 S. The sensor board controls operation of the motors  31 ,  32  based on position information of the lens group holding frames  41 ,  42  detected by the reflection sensor. 
         [0054]    The reflection sensor  21  is arranged on the side of the lens group holding frames  41 ,  42  seen from the direction of the optical axis to detect displacement positions to which the lens group holding frames  41 ,  42  are moved slidingly. For the purpose, in the third wall  91  (partition), the position detection sensor windows  913  are formed to arrange the reflection sensors  21  therein. A planar partition (third wall  91 ) is, as this embodiment, formed at a position where it is in the vicinity of the lens group holding frames  41 ,  42  and parallel to the optical axis L, and the position detection sensor is mounted on the partition wall, which can accurately detect the displacement positions of the lens group holding frames  41 ,  42  that are moved in the direction of the optical axis L. That is, preferably, the partition (third wall  91 ) is arranged at the position where it is in the vicinity of the lens group holding frames  41 ,  42  and parallel to the optical axis L, and at least the position detection sensor windows  913  are formed at positions where they can face the reflection patterns in parallel, respectively. 
         [0055]    The positions of the lens group holding frames  41 ,  42  are controlled in movement by the sensor board constituting the position detection means, and springs  22  are put around the guide poles  51 ,  52 , and the springs  22  are brought into contact with the guide members  51 ,  52 , which can provide a more stable sliding movement of the lens group holding frames  41 ,  42 . That is, the lens group holding frames  2  are biased by the springs  22  toward one direction in sliding movement, which can reduce backlash and hysteresis. 
         [0056]    Also, a stopper mechanism is provided in case of excessive sliding movement due to drive of the motors  31 ,  32  or a defect of the springs  22 . The stopper mechanism is composed of a stopper receiving portion  23  provided on the side of the lens group holding frames  41 ,  42  and a mechanical stopper  24  provided on the side of the lens housing  9 S. In this embodiment, the stopper receiving portion  23  is provided on the guide member  61 , and the mechanical stopper  24  is provided on the partition (third wall  91 ) of the lens housing  9 S to restrict a displacement range of the lens group holding frame  41 . 
         [0057]    In the present embodiment, the mechanical stopper  24  is used as a different component from the third wall  91  of the housing  9 , and arranged on the mechanical stopper mounting portion  914  provided on the third wall  91 . 
         [0058]    The mechanical stopper  24  includes a structure capable of abutting on the stopper receiving portion  23  provided on the guide portions  61  of the lens group holding frame  41 . That is, the mechanical stopper  24  is an approximately flat member in which two ends thereof are bent from the flat body in the same direction to be made approximately perpendicular, thus forming pawls. One of the pawls is formed at a position where it is able to contact on the stopper receiving portion  23  formed on the guide member and on the surface perpendicular to the movement direction of the guide member  61 . The remaining one pawl is latched on the mechanical stopper mounting portion  914 , thus providing a stable latching state of the mechanical stopper  24 . 
         [0059]    As shown in  FIGS. 1 and 6 , in the third wall  91 , a recess is formed in a manner that it matches the shape and the thickness of the mechanical stopper  24 , and the two pawls of the mechanical stopper  24  are inserted into the mechanical stopper mounting portions  914  provided on the third wall  91  of the housing  9  to latch thereon, respectively. At this time, on the side of the outer surface of the third wall  91  of the lens housing  9 S, the mechanical stopper  24  becomes approximately flat with the third wall  91 . Further, subsequently, fixing the motors  31 ,  32  presses the mechanical stopper  24  by the motor  31  while latching it on the third wall  91 , thus fixing. The stopper mechanism causes the mechanical stopper  24  to attach on the stopper receiving portion  23  at a limit position in sliding movement of the lens group holding frame  41 , which can restrict more excessive sliding movement. 
         [0060]    Note that, in this embodiment, the mechanical stopper  24  has been configured to be latched on the mechanical stopper mounting portion  914  on the third wall  91 , thus being fixed, but not limited to this, for example, the mechanical stopper may be formed directly inside of the third wall  91 . 
         [0061]    Before the motors  31 ,  32  are mounted on the third wall  91 , the reflection sensor  21  is mounted. In the embodiment, the position detection sensor window  913  in the third wall  91  is formed so as to match the shape of the reflection sensor  21 , the opening area of the position detection sensor window  913  on the side of the inner surface of the lens housing  9 S is smaller than the area of an outer frame of the reflection sensor  21 , and the reflection sensor  21  is inserted into the position detection sensor window  913  from the outside. Note that the thickness of the third wall  91  is set thicker than that of the reflection sensor  21 , and accordingly the reflection sensor  21  inserted into the position detection sensor window  913  becomes buried in the third wall  91 . 
         [0062]    The motors  31 ,  32  are fixed on the third wall  91 . The output shafts  31   b ,  32   b  of the motors  31 ,  32  are provided with the pinions  81 ,  82  by insertion to be linked therewith. First, the pinions  81 ,  82  are aligned with the output shaft windows  911  formed in third wall  91  and inserted thereinto, respectively, thus allowing motor bodies  31   a ,  32   a  to attach on the third wall  91 . 
         [0063]    Here, on abutting surfaces of the motor bodies  31   a ,  32   a  on the side of the third wall  91 , positioning projections (not shown) are formed at four places, respectively. While, on the third wall  91 , motor positioning holes  9151 ,  9152  for guiding positions at which the motors  31 ,  32  are mounted are formed at four places so as to match mounting positions of the first motor  31  and the second motor  32 , respectively. The motor positioning holes  9151 ,  9152  are the recesses having a bottom, which do not penetrate in the thickness direction. The positioning projections of the motor bodies  31   a ,  32   a  are forced to attach on the motor positioning holes  9151 ,  9152 , and thereby the mounting positions of the motors  31 ,  32  on the third wall  91  are positioned. 
         [0064]    Next, as shown in  FIGS. 5 and 6 , the motors  31 ,  32  are held on the third wall  91  by a clamp  25 . The motor fixing bosses  912  are formed to project, and their projection length corresponds to the thickness of the motor bodies  31   a ,  32   a . The clamp  25  is a flat, elongated member, and on both end portions thereof, openings are formed that serve as washers matching the two motor fixing bosses  912  formed on the third wall  91 . The windows for the clamp  25  are aligned with the motor fixing bosses  912 , respectively, and the clamp  25  is fixed by machine screws  26 , thus the motors  31 ,  32  are fixed between the clamp  25  and the third wall  91 . 
         [0065]    In the lens drive unit installation structure according to the present invention, the motor fixing bosses are formed to fix the motors  31   a ,  32   a  on the partition, thus enhancing accuracy in linking the motor with the lens moving mechanism. The motors  31 ,  32  are the drive source, so that drive force is likely to affect inevitably the motor bodies due to micro vibration or the like, but the motors are fixed on the motor fixing bosses  912  provided on the partition, which can suppress deviation of the motor output shafts caused by the micro vibration of the motor bodies. 
         [0066]    In this embodiment, the method has been described that the motors  31 ,  32  are held by the clamp  25  to fix them on the third wall  91 , but not limited to this, there may be a possible method that a washer portion is formed on the motor body and the motor body is directly fixed on the motor fixing bosses  912  using a machine screw. 
         [0067]    Note that, in the assembling processes described above, a board such as an FPC, or various wirings are appropriately arranged at a predetermined position. 
         [0068]    In the embodiment, using the flat motor, the drive transmission means has adopted the pinions linked with the output shafts  31   b ,  32   b , and the racks, but the present invention is not limited to this. And the lens moving mechanism  2  arranged on the side of the lens group holding frame view from the direction of the optical axis and the motors as the drive source may be housed separately from each other. For example, even if drive transmission means other than the rack and pinion is used, a window for an output shaft into which the output shaft of the motor is inserted may be formed in the partition. 
         [0069]    In the lens drive unit installation structure according to the present invention, the partition (third wall) constituting a part of the lens housing has all a plurality of applications that not only serves as a partition to separate the lens moving mechanism from the motor, but provides the through holes for connecting the motor to the drive transmission means, the position detection means, the stopper mechanism or the like on this partition, and further fixes the motor. In such a manner, the lens moving mechanism and the motors are housed separately from each other, which can not only provide a superior dust resistance, but facilitate positioning, and further make it easier to lay out components. 
         [0070]    The lens drive unit installation structure according to the present invention can allow the drive source from components of the lens drive unit to be housed separately from others, which can provide a superior dust resistance, and be used suitably for an image pickup device of a camera, a measuring apparatus or the like used in an dusty environment.