Abstract:
A lens driving device has first and second driving units for moving first and second lens holders supporting first and second sets of lens elements in an optical axis direction, respectively. The first and second driving units each have a motor, a gear fitted around an output shaft of the motor, a lead screw rotated by the gear, and a nut fitted around the lead screw. The output shafts of the first and second motors overlap each other in their axial direction. The first and second driving units move the first and second lens holders in the optical axis direction via the respective nuts moving in the optical axis direction. An image pickup plane side end face of the motor of the first driving unit is positioned more to the image pickup plane side than a position most to the subject side of the second lens holder is.

Description:
[0001]     This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2005-338016 filed in Japan on Nov. 24, 2005, the entire contents of which are hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to a lens driving device and an image pickup device using it.  
         [0003]     Conventionally, various lens driving mechanisms for driving two or more sets of lens elements of, for example, a zoom lens in the direction of an optical axis of the lens by an actuator have been proposed.  FIG. 14  is a schematic perspective view of a conventional lens driving mechanism (see Japanese Unexamined Patent Publication No.2002-131611) for driving two or more sets of lens elements. In the figure, +Z side is the image pickup element side, and −Z side is the subject side.  
         [0004]     In the lens driving mechanism shown in  FIG. 14 , a first lens holder  2  holding a first set of lens elements  1  and a second lens holder  4  holding a second set of lens elements  3  are guided by a guide shaft  5  to be moved in the direction of the optical axis (Z-axis). On a diagonally upper part of the first lens holder  2  there is provided an upper protrusion  6 , with which a driving shaft  8  is brought into sliding contact by the elastic force of a plate spring  7 . One end of the driving shaft  8  is fixed to a pedestal  9 . The driving shaft  8  is driven to move relative to the pedestal  9  in the optical axis direction by a piezoelectric device  10 . The second lens holder  4  is also provided with an upper protrusion  11  on a diagonally upper part of it. The upper protrusion  11  has sliding contact with a driving shaft  12 , one end of which is fixed to a pedestal  13 . The driving shaft  12  is driven to move in the optical axis direction relative to the pedestal  13  by a piezoelectric device  14 .  
         [0005]     More specifically, the first set of lens elements  1  is driven to move along the driving shaft  8  and the guide shaft  5  by application of a voltage to the piezoelectric device  10 , and the second set of lens elements  2  is driven to move along the driving shaft  12  and the guide shaft  5  by application of a voltage to the piezoelectric device  14 . The piezoelectric device  10  and pedestal  9  for the first set of lens elements  1  are disposed on the second lens side (image pickup element (not shown) side) of the first set of lens elements  1  in the direction of the optical axis. Furthermore, the piezoelectric device  14  and pedestal  13  for the second set of lens elements  3  are disposed on the first lens side (subject side) of the second set of lens elements  3  in the direction of the optical axis.  
         [0006]     The conventional lens driving mechanism has problems as described below. When a zoom camera module is mounted on small-sized portable equipment, it is necessary to reduce the length of the camera module in the optical direction. Reduction in the optical length requires size reduction in the driving mechanism, particularly reduction in the length of it in the direction of the optical axis.  
         [0007]      FIG. 15  schematically shows arrangements of the driving system of  FIG. 14 .  FIG. 15 ( a ) shows an arrangement in the case that the first lens holder  2  holding the first set of lens elements  1  and the second lens holder  4  holding the second set of lens elements  3  are positioned most to the subject side. In contrast to this,  FIG. 15 ( b ) shows an arrangement in the case that the first lens holder  2  and the second lens holder  4  are positioned most to the image pickup element side.  
         [0008]     In  FIG. 15 , the first lens holder  2  is moved between a position at a distance of w 2  from an image pickup plane and a position at a distance of t 2  from the image pickup plane. Furthermore, the second lens holder.  4  is moved between a position at a distance of w 3  from the image pickup plane and a position at a distance of t 3  from the image pickup plane. In order to reduce the length of the camera module in the direction of the optical axis, it is necessary for the piezoelectric device  14  to be positioned as near the image pickup plane as possible. For this purpose, it is necessary that a distance X from the image pickup plane to the driving shaft  12  side end face of the piezoelectric device  14  is less than t 3  and less than w 2 .  
         [0009]     However, “t3” is the distance from the image pickup plane to the second lens holder  4  driven by the piezoelectric device  14  in the case that the second lens holder  4  is positioned most to the subject side. In addition, in order that the second lens holder  4  is driven to move to the position at the distance “t3”, it is necessary for the piezoelectric device  14  to be positioned to the subject side more than the position at the distance “t3”. Consequently, it is impossible that “X”, which is the distance from the image pickup plane to the driving shaft  12  side end face of the piezoelectric device  14 , is made smaller than “t3”, and the length of the lens driving mechanism in the optical axis is large accordingly.  
         [0010]     The piezoelectric device  10  transfers power to the upper protrusion  6  via the driving shaft  8  to drive the first lens holder  2  in the direction of the optical axis. Furthermore, the piezoelectric device  14  transfers power to the upper protrusion  11  via the driving shaft  12  to drive the second lens holder  4  in the direction of the optical axis. A space  15  near the image pickup plane is occupied by parts for driving the second lens holder  4  (see  FIG. 14 ). Thus, it is difficult to locate in the space  15  electrical circuit components which are to be disposed near the image pickup plane and have heights in the direction of the optical axis.  
         [0011]      FIG. 16  shows an arrangement in which the orientation of the piezoelectric device  14  and driving shaft  12  is opposite to the orientation of the piezoelectric device  14  and driving shaft  12  in  FIG. 15 . With this arrangement, it is possible that a space  18  near the image pickup plane corresponding to the space  15  in  FIG. 15  is not occupied by anything. However, in this case, there is a problem that additional members  16  and  17  for transferring the power of the driving shaft  12  to the upper protrusion  11  are newly required and the whole length of the lens driving mechanism in the direction of the optical axis is larger than L in the case shown in  FIG. 15  by the length d of the driving shaft  12 .  
       SUMMARY OF THE INVENTION  
       [0012]     It is therefore an object to provide a lens driving device which drives two sets of lens elements and has a short length in the direction of the optical axis, and an image pickup device using the lens driving device.  
       In order to give a solution to the above problems, there is provided, according to a present invention, a lens driving device, comprising:  
       [0013]     a first lens holder for supporting a first set of lens elements;  
         [0014]     a second lens holder for supporting a second set of lens elements which is disposed in a direction of an optical axis of the first set of lens elements and is positioned more to an image pickup plane side than the first set of lens elements is;  
         [0015]     a first driving unit for driving the first lens holder in the direction of the optical axis; and  
         [0016]     a second driving unit for driving the second lens holder in the direction of the optical axis, wherein  
         [0017]     the first driving unit comprises: 
        a first motor disposed near the first set of lens elements and having an output shaft disposed in parallel with the optical axis of the first set of lens elements;     a first gear fitted around the output shaft of the first motor;     a first lead screw rotated by the first gear; and     a first nut which is fitted around the first lead screw and is movable in the direction of the optical axis,        
 
         [0022]     the second driving unit comprises: 
        a second motor disposed near the second set of lens elements and having an output shaft disposed in parallel with the optical axis of the first set of lens elements;     a second gear fitted around the output shaft of the second motor;     a second lead screw rotated by the second gear; and     a second nut which is fitted around the second lead screw and is movable in the direction of the optical axis,        
 
         [0027]     the output shaft of the first motor and the output shaft of the second motor overlap each other at least partially in an axial direction of the output shafts,  
         [0028]     the first driving unit is designed to move the first lens holder in the direction of the optical axis via the first nut moving in the direction of the optical axis,  
         [0029]     the second driving unit is designed to move the second lens holder in the direction of the optical axis via the second nut moving in the direction of the optical axis, and  
         [0030]     a position of an image pickup plane side end face of the first motor is more to the image pickup plane side than a position most to the subject side of the second lens holder is.  
         [0031]     With the above configuration, the second nut for moving the second lens holder in the direction of the optical axis is moved in the direction of the optical axis by the second lead screw rotated by the second gear mounted to the second motor. Thus, by disposing the second lead screw in such a manner that it extends to the subject side beyond the position of the image pickup plane side end face of the first motor is, the image pickup plane side end face of the first motor can be positioned more to the image pickup plane side than the position most to the subject side of the second lens holder is.  
         [0032]     As a result of this, the subject-side first driving unit is disposed closer to the image pickup plane, so that the length of the lens driving device in the direction of the optical axis can be reduced.  
         [0033]     In one embodiment, the first driving unit is disposed more to a subject side than the second motor is, and parts of the second driving unit other than the second motor are disposed more to the subject side than the second motor is and on a lateral side of the second motor.  
         [0034]     In this embodiment, there are no components of the first driving unit and second driving unit above the second motor. Thus, a space can be provided above the second motor, so that wiring to the terminals of the second motor becomes easy, thereby improving the assemblability of the lens driving device.  
         [0035]     In one embodiment, the image pickup plane has a rectangular shape in outline. The first motor and the second motor each have a terminal base which is provided with terminals for supplying electric power. And, the terminal base of at least one of the first motor and the second motor has a top surface which is inclined relative to directions in which all of sides constituting the outline of the image pickup plane extend.  
         [0036]     In this embodiment, the top surface of the terminal base of at least one of the first motor and the second motor is inclined relative to the directions (for example, directions of X-axis and Y-axis) in which the sides of the rectangular outline of the image pickup plane extend. Thus, wiring to the terminals of the terminal base becomes easy. In particular, in the case that wiring is performed using a FPC (flexible printed circuit board), when the FPC is inserted toward the terminal base in the direction of Y-axis, the degree of bend of an end portion of the FPC connected to the terminals becomes larger than 90 degrees. Thus, the bending stress of the FPC can be made smaller than in the case that the top surface of the terminal base is not inclined, in which case the degree of bend of the FPC is 90 degrees. Therefore, the assemblability and the long term reliability can be improved.  
         [0037]     In one embodiment, the first motor and the second motor each have a terminal base which is provided with terminals for supplying electric power, and the terminals of the first motor and second motor extend in the same direction.  
         [0038]     In this embodiment, due to the fact that the terminals of the first motor and second motor extend in the same direction, when, for example, a FPC for the first motor and a FPC for the second motor are inserted in the same direction, a total length of the two FPCs can be smaller, as compared with that in the case that the terminals of both of the terminal bases are directed in different directions. In addition, wiring can be performed from the same direction, thereby improving the workability during assemble.  
         [0039]     An image pickup device according to the present invention includes the lens driving device as described above.  
         [0040]     That is, this image pickup device uses a lens driving device the length of which in the direction of the optical axis can be reduced. Thus, the whole length of the image pickup device in the direction of the optical axis can be reduced. In addition, if a lens driving device which may have a space above the second motor is used, heat generated from an image sensor mounted in the image pickup device or the second motor can be dissipated through the space, which increases the flexibility in the design of equipment to be installed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0041]     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not intended to limit the present invention, and wherein:  
         [0042]      FIG. 1  is a perspective view of an image pickup device carrying a lens driving device according to the present invention;  
         [0043]      FIG. 2  shows the image pickup device from which a shell of the optical base in  FIG. 1  has been removed;  
         [0044]      FIG. 3  is a perspective view of the lens driving device viewed from a different direction from that in  FIG. 1 ;  
         [0045]      FIG. 4  is an exploded view of the lens driving device shown in  FIG. 3 ;  
         [0046]      FIG. 5  is a perspective view of a zoom driving unit and a focus driving unit of the lens driving device shown in  FIG. 2 ;  
         [0047]      FIG. 6  is an exterior view of a first/second motor;  
         [0048]      FIG. 7  illustrates the operation of a first nut in  FIG. 5 ;  
         [0049]      FIG. 8  is a front view of the first nut;  
         [0050]      FIG. 9  illustrates the operation of a second nut in  FIG. 5 ;  
         [0051]      FIG. 10  is a front view of the second nut;  
         [0052]      FIG. 11  is a schematic diagram showing the positional relationship between components of the focus driving unit and the zoom driving unit;  
         [0053]      FIGS. 12A and 12B  illustrate that the bending stress of a FPC is reduced;  
         [0054]      FIGS. 13A and 13B  illustrate that the length of wiring in the case that the terminals of two motors are directed in the same direction is shorter than that in the case that they are not directed in the same direction;  
         [0055]      FIG. 14  is a perspective view of a conventional lens driving mechanism for driving two sets of lens elements;  
         [0056]      FIG. 15  is a schematic diagram showing the arrangement of the driving systems of the conventional lens driving mechanism shown in  FIG. 14 ; and  
         [0057]      FIG. 16  shows the arrangement in which the orientation of a piezoelectric device is opposite to that in  FIG. 15 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0058]     The present invention will be described in detail below with reference to an embodiment shown in the figures.  FIG. 1  is a perspective view of an image pickup device mounted with a lens driving device of this embodiment. The lens driving device of this embodiment drives a zoom lens and a focus lens.  
         [0059]     The image pickup device  21  has, as shown in  FIG. 1 , a lens driving device  22 , an optical base  23  on which the lens driving device  22  is mounted, and an image sensor  24  attached to the optical base  23 . The housing of the lens driving device  22  and the shell of the optical base  23  are made of rigid resin.  FIG. 2  shows the image pickup device  21  of  FIG. 1  from which the shell of the optical base  23  has been removed. In  FIG. 2 , the lens driving device  22 , the components contained in the optical base  23 , and the image sensor  24  are in sight. A lens fixed to the optical base is omitted from  FIG. 2 . The direction of the optical axis is set as the Z-axis direction, and X-axis and Y-axis are defined on a plane parallel to the image pickup plane. The image pickup plane is a plane on the image sensor  24 .  
         [0060]     In  FIG. 2 , the reference numeral  25  denotes a focus lens holder which supports a set of focus lens elements  26 . The reference numeral  27  denotes a zoom lens holder which supports a set of zoom lens elements  28 . The focus lens guide shaft  29  extending in the direction of Z-axis penetrates the focus lens holder  25 , which is guided in the direction of Z-axis along the focus lens guide shaft  29 . Likewise, the zoom lens guide shaft  30  penetrates the zoom lens holder  27 , which is guided in the direction of Z-axis along the zoom lens guide shaft  30 . Furthermore, the guide shaft  31  is fitted in the fitting groove of the focus lens holder  25  and in the fitting groove of the zoom lens holder  27  to prevent the focus lens holder  25  and the zoom lens holder  27  from rotating in the XY plane. The lens driving device  22  drives the focus lens holder  25  and the zoom lens holder  27  in the direction of Z-axis.  
         [0061]      FIG. 3  is a perspective view of the lens driving device  22  viewed from a different direction from that of  FIG. 1  or  2 .  FIG. 4  is an exploded view of the lens driving device  22  shown in  FIG. 3 . Referring to  FIGS. 3 and 4 , the lens driving device  22  has a focus driving unit  32  for driving the focus lens holder  25  in the direction of Z-axis, a zoom driving unit  33  for driving the zoom lens holder  27  in the direction of Z-axis, a focus driving unit retainer  34 , a focus driving unit receiver  35 , and a zoom driving unit receiver  36 . The focus driving unit retainer  34 , the focus driving unit receiver  35 , and the zoom driving unit receiver  36  are made of rigid resin, and constitute the housing of the lens driving device  22 . The outline of the lens driving device  22  is shaped, as shown in  FIG. 3 , based on rectangular parallelepipeds having sides parallel to X-axis, Y-axis, and Z-axis.  
         [0062]     The zoom driving unit  33  and the focus driving unit  32  are inserted in the zoom driving unit receiver  36  and the focus driving unit receiver  35  in the direction of Z-axis and are fixed to them. The focus driving unit retainer  34 , the focus driving unit receiver  35 , and the zoom driving unit receiver  36  are coupled to each other with screws or adhesive to form the lens driving device  22  as shown in  FIG. 3 .  
         [0063]      FIG. 5  is a perspective view of the zoom driving unit  3  and the focus driving unit  32  in the state that the focus driving unit retainer  34 , the focus driving unit receiver  35  and the zoom driving unit receiver  36  are removed from the lens driving device  22 . The focus driving unit  32  includes a first motor  37 , a first pinion gear  38 , a first idle gear  39 , a first lead screw  40 , and a first nut  41 . The zoom driving unit  33  includes a second motor  42 , a second pinion gear  43 , a second idle gear  44 , a second lead screw  45 , and a second nut  46 . In  FIGS. 4 and 5 , screw threads of the first lead screw  40  and the second lead screw  45  and teeth of each of the gears are omitted. The threads and teeth are omitted also in the other figures.  
         [0064]      FIG. 6  is an exterior view of the first motor  37  or second motor  42 . Since the first motor  37  and the second motor  42  are completely identical in configuration, the first motor  37  and the second motor  42  will be described below using the same figure ( FIG. 6 ). Each of the first motor  37  and the second motor  42  is a so-called stepping motor, and an output shaft  48  of it protrudes from an end face  47  of the motor case. Furthermore, a terminal base  49  is provided on part of the cylindrical periphery, and terminals  50  protrude from the terminal base  49  in a direction perpendicular to the direction in which the output shaft  48  extends.  
         [0065]     The first motor  37  for the focus driving unit  32  is disposed in such a manner that its output shaft  48  protrudes in the direction of Z-axis toward the image pickup plane. In contrast to this, the second motor  42  for the zoom driving unit  33  is disposed in such a manner that its output shaft  48  protrudes in the direction of Z-axis toward the subject side so as to overlap the output shaft  48  of the first motor  37  in the direction of Z-axis. Like this, the first motor  37  and the second motor  42  are disposed with their output shafts overlapping each other in the direction of Z-axis, so that it becomes possible to reduce the length of the lens driving device  22  in the direction of Z-axis by the length of the output shaft  48 .  
         [0066]     Furthermore, the first motor  37  is disposed to be as close to the second motor  42  as possible in order to reduce the length of the image pickup device  21 . In addition, the end face  47  of the motor case of the first motor  37  is positioned more to the image pickup plane side than the zoom lens holder  27  in a state in which the zoom lens holder  27  has been moved most to the subject side. Furthermore, the top faces of the terminal bases  49  of the first motor  37  and second motor  42  are inclined about  10  degrees counterclockwise relative to the XZ-plane, namely toward outside in short (see  FIG. 2 ), when viewed toward the image pickup plane in the direction of Z-axis. Because of this, since the terminals  50  protrude in the same direction, handling of FPCs (flexible printed circuit boards), etc. becomes easy, whereby assemblability is improved. Furthermore, size reduction in the lens driving device  22  itself becomes possible.  
         [0067]     The first lead screw  40  is disposed near the focus lens guide shaft  29  with respect to the direction of Y-axis and in parallel with the Z-axis and is capable of rotating around its own center axis. A gear  51  is fitted coaxially to an image pickup plane side end portion of the first lead screw  40  such that the gear  51  rotates together with the first lead screw  40 . The length of the first lead screw  40  is nearly equal to the length of the first motor  37  in the direction of the optical axis. The first nut  41  is fitted around the first lead screw  40  and is capable of moving in the direction of the optical axis (Z-axis) as the first lead screw  40  rotates. Furthermore, the first nut  41  is capable of coming into contact with the focus lens holder  25  to move the focus lens holder  25  in the direction of Z-axis.  
         [0068]      FIG. 7  illustrates the operation of the first nut  41 .  FIG. 8  is a front view of the first nut  41 . In  FIG. 7 , the focus driving unit receiver  35  and the first nut  41  are illustrated separately, and other components are omitted, for easy understanding. In  FIG. 7 , the focus driving unit receiver  35  is provided with a first surface  52  (shown with hatching to make it easily visible) extending in the direction of Z-axis and in parallel with the ZY-plane, and a second surface  53  extending in the direction of Z-axis and perpendicularly to the first surface  52  (i.e. in parallel with the ZX-plane), around the first lead screw  40  (omitted in  FIG. 7 ) disposed in the focus driving unit receiver  35 . On the other hand, as shown in  FIG. 8 , the first nut  41  has, on its periphery, a face  54  which makes sliding contact with the first surface  52  of the focus driving unit receiver  35 , and a face  55  which makes sliding contact with the second surface  53  of the focus driving unit receiver  35 , and the face  54  and the face  55  meet together to form a first protrusion  56 . The first protrusion  56  of the first nut  41  is positioned in a corner defined between the first surface  52  and second surface  53  of the focus driving unit receiver  35  that meet each other. As a result of this, when the first lead screw  40  rotates, the first protrusion  56  of the first nut  41  rests against the first surface  52  or second surface  53  of the focus driving unit receiver  35 , so that the rotation of the first nut  41  is stopped. Thus, with the rotation of the first lead screw  40 , the first nut  41  moves in the direction of Z-axis, guided by the first surface  52  and the second surface  53 .  
         [0069]     As shown in  FIG. 5 , the first pinion gear  38  is coaxially fitted around the output shaft  48  of the first motor  37 , and rotates along with the output shaft  48 . The first idle gear  39  is disposed so as to mesh with both of the first pinion gear  38  and the gear  51  of the first lead screw  40 . The first idle gear  39  is positioned apart from the first lead screw  40  in a direction perpendicular to the optical axis and is attached rotatably to a shaft provided in the zoom driving unit receiver  36 .  
         [0070]     The second lead screw  45  is disposed in substantially parallel with the first lead screw  40  and between a plane that is parallel with the XZ-plane and includes the focus lens guide shaft  29  and a plane that is parallel with the XZ-plane and includes the zoom lens guide shaft  30 . The second lead screw  45  is capable of rotating around its own center axis. A gear  57  is coaxially fitted around a subject side end portion of the second lead screw  45  such that the gear  57  rotates together with the second lead screw  45 . The second nut  46  is fitted around the second lead screw  45  and is capable of moving in the direction of the optical axis (Z-axis) as the second lead screw  45  rotates. Furthermore, the second nut  46  is capable of coming into contact with the zoom lens holder  27  to move the zoom lens holder  27  in the direction of Z-axis.  
         [0071]      FIG. 9  illustrates the operation of the second nut  46 .  FIG. 10  is a front view of the second nut  46 . In  FIG. 9 , the zoom driving unit receiver  36  and the second nut  46  are illustrated separately, and other components are omitted, for easy understanding. In  FIG. 9 , the zoom driving unit receiver  36  is provided with a third surface  58  (shown with hatching to make it easily visible) extending in the direction of Z-axis and in parallel with the ZY-plane, and a fourth surface  59  extending in the direction of Z-axis and perpendicularly to the third surface  58  (i.e. in parallel with the ZX-plane), around the second lead screw  45  (omitted in  FIG. 9 ) disposed in the zoom driving unit receiver  36 . On the other hand, as shown in  FIG. 10 , the second nut  46  has, on its periphery, a face  60  which makes sliding contact with the third surface  58  of the zoom driving unit receiver  36 , and a face  61  which makes sliding contact with the fourth surface  59  of the zoom driving unit receiver  36 , and the face  60  and the face  61  meet together to form a second protrusion  62 . The second protrusion  62  of the second nut  46  is positioned in a corner defined between the third surface  58  and fourth surface  59  of the zoom driving unit receiver  36  that meet together. As a result of this, when the second lead screw  45  rotates, the second protrusion  62  of the second nut  46  rests against the third surface  58  or fourth surface  59  of the zoom driving unit receiver  36 , so that the rotation of the second nut  46  is stopped. Thus, with the rotation of the second lead screw  45 , the second nut  46  moves in the direction of Z-axis, guided by the third surface  58  and the fourth surface  59 .  
         [0072]     Thus, the first nut  41  is able to move the focus lens holder  25  in the direction of Z-axis. Also, the second nut  46  is able to move the zoom lens holder  27  in the direction of Z-axis.  
         [0073]     As shown in  FIG. 5 , the second pinion gear  43  is coaxially fitted around the output shaft  48  of the second motor  42 , and rotates along with the output shaft  48 . The second idle gear  44  is disposed so as to mesh with both of the second pinion gear  43  and the gear  57  of the second lead screw  45 . Furthermore, the second idle gear  44  has, on its subject side end portion, a projection (not shown) which projects in the direction of the optical axis, and on its image pickup plane side end portion, the second idle gear  44  has a pit (not shown) which is parallel with the direction of the optical axis. The projection of the second idle gear  44  is received in a pit (not shown) provided in the focus driving unit receiver  35 . On the other hand, the pit of the second idle gear  44  receives an axis provided in the zoom driving unit receiver  36 . In this manner, the second idle gear  44  is held rotatably by the focus driving unit receiver  35  and the zoom driving unit receiver  36 .  
         [0074]      FIG. 11  is a schematic diagram showing the positional relationship between components of the focus driving unit  32  and the zoom driving unit  33 . In  FIG. 11 , the focus lens holder  25  supporting the set of focus lens elements  26  (see  FIG. 2 ) on the subject side is driven to move in the direction of the optical axis by the focus driving unit  32 , while the zoom lens holder  27  supporting the set of zoom lens elements  28  (see  FIG. 2 ) on the image pickup plane side is driven to move in the direction of the optical axis by the zoom driving unit  33 .  
         [0075]     The first motor  37 , which is a component of the focus driving unit  32 , is disposed near and on a lateral side of the focus lens holder  25 . The output shaft  48  of the first motor  37  is disposed in parallel with the optical axis, and fitted with the first pinion gear  38 . On the other hand, the second motor  42 , which is a component of the zoom driving unit  33 , is disposed near and on a lateral side of the zoom lens holder  27 . The output shaft  48  of the second motor  42  is disposed in parallel with the optical axis, and fitted with the second pinion gear  43 . The output shaft  48  of the first motor  37  and the output shaft  48  of the second motor  42  overlap each other in the axis direction.  
         [0076]     Furthermore, the focus lens holder  25  is moved in the direction of the optical axis on a lateral side of the first motor  37  by the first nut  41  which is fitted around the first lead screw  40  to which the gear  51  rotated by the first pinion gear  38  is coaxially fitted. Thus, the image pickup plane side end face of the motor case of the first motor  37  in the focus driving unit  32  is able to be positioned to the image pickup plane side to a larger extent than the focus lens holder  25  in its position most to the image pickup plane side is.  
         [0077]     The zoom lens holder  27  is moved in the direction of the optical axis on a lateral side of the second motor  42  by the second nut  46  which is fitted around the second lead screw  45  to which the gear.  57  rotated by the second pinion gear  43  is coaxially fitted. In addition, the second idle gear  44  which meshes with both of the second opinion gear  43  and the gear  57  extends close to the subject side end face of the motor case of the first motor  37  in parallel with the optical axis. Thus, the image pickup plane side end face of the motor case of the first motor  37  is able to be positioned to the image pickup plane side to a larger extent than the zoom lens holder  27  that assumes its position  27 ′ most to the subject side.  
         [0078]     As is apparent from the above, in this embodiment, the distance B from the image pickup plane to the image pickup plane side end face of the motor case of the first motor  37 , which is a component of the focus driving unit  32  on the subject side, is smaller than the distance C from the image pickup plane to the focus lens holder  25  when the latter is positioned most to the image pickup plane side. Furthermore, the distance B is smaller than the distance D from the image pickup plane to the zoom lens holder  27 ′ positioned most to the subject side. Consequently, size reduction in the image pickup device  21  can be achieved in such a way that the focus driving unit  32  on the subject side is disposed more to the image pickup plane side to reduce the length of the lens driving device  22  in the direction of the optical axis.  
         [0079]     Furthermore, as shown in  FIG. 5 , the focus driving unit  32  is disposed to the subject side more than the second motor  42  is. In addition, parts of the zoom driving unit  33  other than the second motor  42  are disposed on the subject side of the second motor  42  and on a lateral side of the second motor  42 . Thus, there is no component of the focus driving unit  32  and zoom driving unit  33  above the second motor  42  positioned on the image pickup plane side. Because of this, as shown in  FIG. 1 , a space  65  can be provided above the second motor  42 . That is, according to this embodiment, parts which are long in the direction of Z-axis like a chip  67  can be disposed on the substrate  66  on which the image sensor  24  is mounted, whereby the length of the image pickup device  21  can be reduced. In addition, heat generated by the image sensor  24  can be dissipated through the space  65 .  
         [0080]     Furthermore, according to this embodiment, spaces can be provided above the first motor  37  and the second motor  42  as described above. For this reason, as shown in  FIG. 2 , spaces can be provided around the terminals  50  of the first motor  37  and second motor  42 . Thus, wiring to the terminals  50  becomes easy, thereby improving the assemblability.  
         [0081]     Furthermore, according to this embodiment, as shown in  FIG. 2 , the top faces of the terminal bases of the first motor  37  and second motor  42  extend in the direction of the optical axis (Z-axis) and are inclined about 10 degrees toward the outside from the optical axis (Z-axis) side. Thus, wiring from the terminals  50  becomes easy. In particular, as shown in  FIG. 12A , when a FPC  71  is inserted downward in the direction of Y-axis, the degree of bend of the FPC  71  connected to the terminals  50  becomes larger than 90 degrees. Thus, as shown in  FIG. 12B , the bending stress of the FPC  71  in this case can be made smaller than that in the case that the top face of the terminal base  49  is not inclined (in which case the bending angle of the FPC  71  is 90 degrees), thereby improving the assemblability and the long term reliability.  
         [0082]     Furthermore, in this embodiment, the terminals  50  of the terminal bases  49  of the first motor  37  and second motor  42  are directed in the same direction. Because of this, as shown in  FIG. 13A , when a FPC  72  for the first motor  37  and a FPC  73  for the second motor  42  are inserted downward in the direction of Y-axis, a necessary length of the FPC  73  connected to the terminals  50  of the second motor  42  can be made shorter, as compared with the case that the terminals  50  of both of the terminals bases  49  are directed in different directions as shown in  FIG. 13B  (i.e., the length of the FPC  73 &lt;the length of the FPC  73 ′). In addition, since the terminals of both of the terminal bases  49  are directed in the same direction, wirings from the same direction are possible. Thus, the assemblability and the workability are improved.  
         [0083]     In short, according to this embodiment, as described above, circuit components can be easily placed on the substrate  66  of the image sensor  24 , so that the length of the image pickup device  21  in the direction of the optical axis can be reduced. In addition, heat generated by the image sensor  24 , the first motor  37 , or the second motor  42  can be dissipated, thereby increasing the flexibility in the design of equipment to be mounted.  
         [0084]     In the aforementioned embodiment, the output shaft  48  of the first motor  37  and the output shaft  48  of the second motor  42  fully overlap each other. However, an embodiment in which the output shafts  48  partially overlap each other is also included in the scope of this invention.  
         [0085]     Embodiments of the invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.