Abstract:
A lens barrel with a shutter unit. While the lens barrel is retracted to obtain a collapsed state or advanced to obtain a photographing state, the flexible printed circuit board of the shutter unit is bendable so as to provide a variable length for the rotation of the shutter unit  71  around the rotary axis J 2  parallel with the optical axis J 1 . When the lens barrel is operated in the photographing state, the flexible printed circuit board is foldable so as to provide a variable length for the movement of the shutter unit  71  in the optical axis J 1 . The flexible printed circuit board can support flexibly without twisting and loosening. The lens barrel further includes a restraint member to bring the shutter unit  71  rotating around the central axis and to restrain the rotation of the shutter unit  71.

Description:
BACKGROUND  
       [0001]     The invention relates to lens barrels, and in particular, to lens barrels with a shutter unit which is held in a moveable manner.  
         [0002]     In a camera, a control circuit transmits signals via a flexible printed circuit board to drive a shutter unit disposed in the lens barrel. When the shutter unit is moved along an optical axis of the lens barrel, the sufficient length of the flexible printed circuit board is capable of holding the shutter unit without generating loose.  
         [0003]     When the shutter unit rotates around the central axis of the lens barrel, the flexible printed circuit board may break or interfere with other members in the lens barrel. Accordingly, in Japan Pub. No. 2003-140022, the shutter unit is a non-rotary member such that it can move simply along the optical axis.  
         [0004]     Nevertheless, to obtain a thinner, miniaturized lens barrel, the flexible printed circuit board and the shutter unit must rotate together. That is, if the shutter unit can only move in the lens barrel, it may be difficult to miniaturize and thin the lens barrel.  
       SUMMARY  
       [0005]     A lens barrel is provided. An exemplary embodiment of a lens barrel comprises a shutter unit, a driving mechanism, and a flexible printed circuit board. The shutter unit comprises a shutter blade and an actuator. The driving mechanism drives the shutter unit to move along an optical axis and rotate around a rotary axis parallel with the optical axis in the lens barrel. The flexible printed circuit board comprises a first flexible portion and a second flexible portion and connects the actuator of the shutter unit and a driving circuit outside of the lens barrel. The first flexible portion is foldable so as to provide a first variable length for the movement of the shutter unit along the optical axis. The second flexible portion is bendable so as to provide a second variable length for the rotation of the shutter unit around the rotary axis parallel with the optical axis.  
         [0006]     Additionally, the lens barrel further comprises a restraint member bringing the shutter unit rotating around a central axis of the lens barrel and restraining the rotation of the shutter unit. The flexible printed circuit board further comprises a central portion located between the first flexible portion and the second flexible portion. The central portion is fixed to the restraint member.  
         [0007]     Furthermore, the lens barrel is retracted to obtain a collapsed state and advanced to obtain a photographing state. The shutter unit is moved and rotated by the driving mechanism when the lens barrel is operated from the collapsed state to the photographing state, and is simply moved when the lens barrel is operated in the photographing state.  
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0008]     The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:  
         [0009]      FIG. 1  is a cross section of an embodiment of a lens barrel in a photographing state in minimum zoom state;  
         [0010]      FIG. 2  is a cross section of a focus driving mechanism of the lens barrel in  FIG. 1 ;  
         [0011]      FIG. 3  is a front perspective view of the lens barrel in the photographing state;  
         [0012]      FIG. 4  is a schematic view of a fixed barrel from the outer periphery thereof;  
         [0013]      FIG. 5  is a cross section of a cam groove of the fixed barrel;  
         [0014]      FIG. 6  is a schematic view of a rotary barrel from the outer periphery thereof;  
         [0015]      FIG. 7  is a schematic view of a restraining barrel from the outer periphery thereof;  
         [0016]      FIG. 8  is a cross section of a cam follower of the restraining barrel;  
         [0017]      FIG. 9  is a schematic view of a cam barrel from the outer periphery thereof;  
         [0018]      FIG. 10  is a schematic view of a forward barrel from the outer periphery thereof;  
         [0019]      FIG. 11  is a schematic view of a first lens frame from the outer periphery thereof;  
         [0020]      FIG. 12  is a schematic view of a second lens frame from the outer periphery thereof;  
         [0021]      FIG. 13  is a cross section of the lens barrel in a collapsed state;  
         [0022]      FIG. 14  is a front perspective view of the lens barrel in the collapsed state;  
         [0023]      FIG. 15  is a front view of the lens barrel in the collapsed state;  
         [0024]      FIG. 16  is a front view of the lens barrel in the photographing state;  
         [0025]      FIG. 17  is a schematic view showing positions of the cam groove of the fixed barrel;  
         [0026]      FIG. 18  is a schematic view showing positions of a cam groove of the restraining barrel;  
         [0027]      FIG. 19  is a schematic view showing positions of a cam groove of the cam barrel;  
         [0028]      FIG. 20  is a cross section of the lens barrel in the photographing state in full zoom state;  
         [0029]      FIG. 21  is a graph showing the relationship between angles of the rotary barrel and distance traveled by moving devices along an optical axis;  
         [0030]      FIG. 22  is a front view of a shutter unit and a flexible printed circuit board;  
         [0031]      FIG. 23  is a cross section of the shutter unit;  
         [0032]      FIG. 24  is a cross section of the lens barrel around the shutter unit in the collapsed state;  
         [0033]      FIG. 25  is a perspective view from an arrow B in  FIG. 24 ;  
         [0034]      FIG. 26  is a schematic view of the flexible printed circuit board from an arrow C in  FIG. 25 ;  
         [0035]      FIG. 27  is a cross section of the lens barrel around the shutter unit in the photographing state in minimum zoom state;  
         [0036]      FIG. 28  is a perspective view from an arrow E in  FIG. 27 ; and  
         [0037]      FIG. 29  is a cross section of the lens barrel around the shutter unit in the photographing state in full zoom state. 
     
    
     DETAILED DESCRIPTION  
       [0038]      FIGS. 1-29  show an embodiment of a lens barrel  2 , applied here in a digital camera with zoom function.  
         [0039]      FIG. 1  is a cross section of the lens barrel  2  in a photographing state in a minimum zoom state. A photographic optical system comprises a first lens group  31 , a second lens group  32 , a third lens group  33 , a low pass filter  34 , and a charge coupled device (CCD)  35  arranged consecutively from a side nearest an object to be photographed. The CCD  35  is used as an image-generating device. J 1  represents an optical axis of the photographic optical system. The optical axis J 1  is parallel to a central axis J 2  of the lens barrel  2 , and is eccentric from the central axis J 2 . Zoom operation is accomplished by moving the first and second lens groups  31  and  32  along the optical axis J 1 . Focus operation is accomplished by moving the third lens group  33  along the optical axis J 1 . A light from the side nearest the object reaches the CCD  35  via the first lens group  31 , the second lens group  32 , the third lens group  33 , and the low pass filter  34  consecutively. In the following description, an optical axis direction means a direction that is parallel to the optical axis J 1 .  
         [0040]     A fixed barrel  61  is fixed to the body  1 . A CCD holder  21  is fixed to the fixed barrel  61  to cover an opening of the fixed barrel  61 . The low pass filter  34  is disposed in front of the CCD  35 , and supported at an opening portion  21   a  of the CCD holder  21 . The CCD  35  is supported along with a heat-dissipation plate  22 , and fixed to the CCD holder  21  via the heat-dissipation plate  22 . A flexible printed circuit board  23  for the CCD  35  is located behind the heat-dissipation plate  22 , to transmit an electronic signal from the CCD  35 .  
         [0041]     The third lens group  33  and a focus driving mechanism  3  for driving the third lens group  33  are assembled with respect to the CCD holder  21 .  FIG. 2  is a cross section of the focus driving mechanism  3 . A third lens frame  41  for supporting the third lens group  33  is slidably supported in the optical axis direction via a pair of guide shafts  42  and  43  disposed on the CCD holder  21 . The guide shaft  42  is the main guide shaft of the third lens frame  41 . The guide shaft  43  limits the rotation of the third lens frame  41 , and is slidably inserted into guide holes  41   a  and  41   b  on the third lens frame  41 .  
         [0042]     A focus motor  44  is disposed on the side of the CCD  35  and the third lens group  33 . The focus motor  44  is also located inside the fixed barrel  61 , and fixed with respect to the CCD holder  21 . The rotational driving force of the focus motor  44  is transmitted to a screw shaft  48  via a focus motor gear  45 , focus gears  46  and  47 . The third lens frame  41  moves forward/backward along the optical axis direction by means of the screwing relationship between the screw shaft  48  and a nut  49 . Since the rotational driving force of the focus motor  44  is decelerated by the focus gears  46  and  47 , the screw shaft  48  receives sufficient rotary torque. The third lens frame  41  is biased along the optical axis direction by a spring  50 . The focus motor  44  is controlled by a control circuit of the camera via a flexible printed circuit board  51  located behind the CCD holder  21 .  
         [0043]      FIG. 3  is a front perspective view of the lens barrel  2  in the photographing state. A zoom motor  81  and a deceleration gear train  82  are located above the fixed barrel  61 . The driving force of the zoom motor  81  is transmitted to a zoom gear  83  via the deceleration gear train  82 . The zoom gear  83  is supported by a gear shaft  84  parallel to the optical axis direction, and rotates with respect to the fixed barrel  61 . The zoom motor  81 , the deceleration gear  82 , and the zoom gear  83  drive the expansion mechanism of the lens barrel  2 . The zoom motor  81  is controlled by the control circuit of the camera via the flexible printed circuit board  51  located behind the CCD holder  21 .  
         [0044]      FIG. 4  is a schematic view of the fixed barrel  61  from the outer periphery thereof. Three cam grooves  61   a , for guiding a rotary barrel  62 , and three cam grooves  61   b , for guiding a restraining barrel  63 , are formed at the inner periphery of the fixed barrel  61 . The cam grooves  61   a  are deeper than the cam grooves  61   b . The cam grooves  61   a  and  61   b  comprise the same area  61   c  with same cam trajectory. A cam groove shaped as shown in  FIG. 5  is formed in area  61   c.    
         [0045]      FIG. 6  is a schematic view of the rotary barrel  62  from the outer periphery thereof. The rotary barrel  62  is located inside the fixed barrel  61 , and comprises holes  62   a . Three follower pins  64  are inserted into the holes  62   a , engaging with the cam grooves  61   a  of the fixed barrel  61 . Protrusions  62   b  are formed at the outer periphery of the rotary barrel  62  around the inserted follower pins  64 , and shaped to be substantially engaged with the cam grooves  61   a  of the fixed barrel  61 . A gear portion  62   c  is disposed at the outer periphery of the rotary barrel  62  to mesh with the zoom gear  83 . The rotational driving force is transmitted by the driving mechanism, comprising the zoom motor  81 , the deceleration gear  82 , and the zoom gear  83 . The rotary barrel  62  is rotated around the central axis J 2  by the rotation of the zoom gear  83 , such that the rotary barrel  62  is driven forward/backward along the cam grooves  61   a  of the fixed barrel  61 .  
         [0046]      FIG. 7  is a schematic view of the restraining barrel  63  from the outer periphery thereof. The restraining barrel  63  is located inside the rotary barrel  62 . Claws  63   a , disposed at the outer periphery of the restraining barrel  63 , engage with grooves  62   d  formed at the inner periphery of the rotary barrel  62 . The restraining barrel  63  is rotatably supported, and movement thereof is limited to the optical axis direction with respect to the rotary barrel  62 . Three cam followers  63   b  are formed at the outer periphery of the restraining barrel  63  to engage with the cam grooves  61   b  of the fixed barrel  61 . The cam follower  63   b  of the restraining barrel  63  has a parrallelogram cross section as shown in  FIG. 8 . Each cam follower  63   b  comprises a flat surface  63   c , engaging straight areas  61   d  and  61   e  of the cam groove  61   b  of the fixed barrel  61 , and a flat surface  63   d  engaging with inclined areas  61   c  of the cam groove  61   b  of the fixed barrel  61 .  
         [0047]      FIG. 9  is a schematic view of a cam barrel  65  from the outer periphery thereof. The cam barrel  65  is located inside the restraining barrel  63 , and comprises three cam followers  65   a  at the outer periphery. The cam followers  65   a  engage the cam grooves  63   e  disposed at the inner periphery of the restraining barrel  63 . The cam barrel  65  is driven forward/backward via the cam grooves  63   e  of the restraining barrel  63  by means of the rotation of the cam barrel  65  with respect to the restraining barrel  63 . Three guiding shafts  66  are inserted into holes  65   b  of the cam barrel  65  through the holes  63   f  of the restraining barrel  63  to engage forward grooves  62   e  disposed at the inner periphery of the rotary barrel  62  along the optical axis direction. Thus, the cam barrel  65  cannot rotate with respect to the rotary barrel  62 , but can move with respect to the rotary barrel  62  along the optical axis direction. That is, the restraining barrel  63  can rotate with respect to the rotary barrel  62 . The cam barrel  65  is driven forward/backward along the cam grooves  63   e  of the restraining barrel  63 .  
         [0048]      FIG. 10  is a schematic view of a forward barrel  67  from the outer periphery thereof. The forward barrel  67  is located inside the cam barrel  65 . The movement of claws  65   c , disposed at the inner periphery of the cam barrel  65 , to the optical axis direction is limited by clipping the claws  65   c  between protrusions  67   a  and  67   b  disposed at the outer periphery of the forward barrel  67 . The forward barrel  67  is supported to be rotatable with respect to the cam barrel  65 . Guide claws  67   c , disposed at the outer periphery of the forward barrel  67 , engage with forward grooves  63   g  disposed at the inner periphery of the restraining barrel  63  along the optical axis direction. Thus, the forward barrel  67  cannot rotate with respect to the restraining barrel  63 , but can move with respect to the restraining barrel  63  along the optical axis direction.  
         [0049]      FIG. 11  is a schematic view of a first lens frame  68  from the outer periphery thereof. The first lens frame  68  is located inside the cam barrel  65  to support the first lens group  31 . Three follower pins  69  are inserted into holes  68   a  of the first lens frame  68 . A follower portion  69   a , formed at the outer periphery of the follower pin  69 , engages the cam groove  65   d  disposed at the inner periphery of the cam barrel  65 . A guide portion  69   d , disposed at the inner periphery of the follower pin  69 , engages a guide hole  67   d  of the forward barrel  67  along the optical axis direction. Thus, the first lens frame  68  is driven forward/backward along the cam groove  65   d  of the cam barrel  65  in the optical axis direction by means of the rotation of the forward barrel  67  with respect to the cam barrel  65 , and the rotation of the cam barrel  65  with respect to the restraining barrel  63 . That is, the first lens frame  68  is not moved, with respect to the restraining barrel  63 , by the rotation of the forward barrel  67 .  
         [0050]      FIG. 12  is a schematic view of a second lens frame  70  from the outer periphery thereof. The second lens frame  70  is located inside the forward barrel  67  to support the second lens group  32 . Three cam followers  70   a  are formed at the outer periphery of the second lens frame  70 , and engage the cam grooves  65   e  disposed at the inner periphery of the cam barrel  65 . Bases  70   b  of the cam followers  70   a  of the second lens frame  70  engage the guide holes  67   e  of the forward barrel  67  along the optical axis direction. Thus, the second lens frame  70  is driven forward/backward along the cam groove  65   d  of the cam barrel  65  along the optical axis direction by means of rotation of the forward barrel  67  with respect to the cam barrel  65 , and rotation of the cam barrel  65  with respect to the restraining barrel  63 . That is, the second lens frame  70  is not moved, with respect to the restraining barrel  63 , by the rotation of the forward barrel  67 .  
         [0051]     A shutter unit  71  is mounted at the second lens frame  71 , controlling entry of incident light from the side nearest the object. A flexible printed circuit board  72  connects an actuator  71   a  of the shutter unit  71  and the control circuit of the camera, and is connected to the flexible printed circuit board  51 , disposed behind the CCD holder  21 , through the lens barrel  2  from the shutter unit  71 .  
         [0052]     A bias spring  73  is disposed between the second lens frame  70  and the first lens frame  68  to bias the second lens frame  70  and the first lens frame  68  from the optical axis direction. Thus, meshing between the first lens frame  68  and the cam barrel  65 , and meshing between the second lens frame  70  and the cam barrel  65  remain intact, stabilizing the optical characteristics.  
         [0053]     The motion of the lens barrel  2  from the collapsed state to the photographing state is described in the following.  
         [0054]      FIG. 13  is a cross section of the lens barrel  2  in the collapsed state.  FIG. 14  is a front perspective view of the lens barrel  2  in the collapsed state. J 3  represents a central axis of the first and second lens groups  31  and  32 . The first and second lens groups  31  and  32  are located at the side of the third lens group  33 , the low pass filter  34 , the CCD  35 , and the focus driving mechanism  3 , and away from the optical axis J 1 . That is, the first and second lens groups  31  and  32 , the third lens group  33 , the low pass filter  34 , the CCD  35 , and the focus driving mechanism  3  are substantially received at the same plane perpendicular to the optical axis direction.  
         [0055]     When the first and second lens groups  31  and  32  rotate around the central axis J 2  of the lens barrel  2 , they extend to the photographing state as shown in  FIG. 1 . As seen from the front side of the lens barrel  2 , the first and second lens groups  31  and  32  in  FIG. 15  rotates along a direction Z 1 , and moves to the photographing state as shown in  FIG. 16 . In the photographing state, since the central axis J 3  of the first and second lens groups  31  and  32  is the same as the optical axis J 1 , an eccentric distance between the central axis J 2  of the lens barrel  2  and the optical axis J 1  is equal to that between the central axis J 2  of the lens barrel  2  and the central axis J 3  of the first and second lens groups  31  and  32 .  
         [0056]     Referring to  FIGS. 17-19 , in the collapsed state of the lens barrel  2 , the follower pins  64 , inserted into the rotary barrel  62 , are in the position  61 ( 1 ) of the cam groove of the fixed barrel  61 . The cam followers  63   b  of the restraining barrel  63  are in the position  61 ( 11 ) of the cam groove of the fixed barrel  61 . The cam followers  65   a  of the cam barrel  65  are in the position  63 ( 1 ) of the cam groove of the restraining barrel  63 . The follower pins  69 , inserted into the first lens frame  68 , are in the position  65 ( 1 ) of the cam groove of the cam barrel  65 . The cam followers  70   a  of the second lens frame  70  are in the position  65 ( 11 ) of the cam grooves of the cam barrel  65 .  
         [0057]     When the rotary barrel  62  rotates around the central axis J 2  by means of rotation of the zoom gear  83 , the follower pin  64  moves from the position  61 ( 1 ) of the cam groove of the fixed barrel  61  to the position  61 ( 2 ), and extends along the optical axis direction. The restraining barrel  63  limits the rotary barrel  62  to move toward the optical axis direction. Since the restraining barrel  63  is guided by the cam groove  61   b  of the fixed barrel  61 , it extends from the position  61 ( 11 ) of the cam groove of the fixed barrel  61  along the position  61 ( 12 ) in the optical axis direction. When the restraining barrel  63  moves to the position  61 ( 12 ) from the position  61 ( 11 ), the cam follower  65   a  of the cam barrel  65  is moved to the position  63 ( 2 ) from the position  63 ( 1 ) of the cam groove of the restraining barrel  63  since the restraining barrel  63  is rotated with respect to the rotary barrel  62 . At the same time, since the cam barrel  65  rotates with respect to the restraining barrel  63 , the follower pin  69  moves to the position  65 ( 2 ) from the position  65 ( 1 ) of the cam groove of the cam barrel  65 , and the cam follower  70   a  of the second lens frame  70  moves to the position  65 ( 12 ) from the position  65 ( 11 ) of the cam groove of the cam barrel  65 .  
         [0058]     When the follower pin  64  reaches the position  61 ( 2 ) of the cam groove of the fixed barrel  61 , the cam follower  63   b  of the restraining barrel  63  is moved to the position  61 ( 12 ) of the cam groove of the fixed barrel  61 , the cam follower  65   a  of the cam barrel  65  is moved to the position  63 ( 2 ) of the cam groove of the restraining barrel  63 , the follower pin  69  is moved to the position  65 ( 2 ) of the cam groove of the cam barrel  65 , and the cam follower  70   a  of the second lens frame  70  is moved to the position  65 ( 12 ) of the cam groove of the cam barrel  65 .  
         [0059]     By means of the above operation, the restraining barrel  63  extends in the optical axis direction. Also, since the cam barrel  65 , the first lens frame  68 , and the second lens frame  70  extends along the optical axis direction, the first and second lens groups  31  and  32  extends on the side near the object in the optical axis direction.  
         [0060]     Before the first and second lens groups  31  and  32  start to rotate, they can move to a position that does not interfere with the third lens group  33 , the low pass filter  34 , the CCD  35 , and the focus driving mechanism  3 .  
         [0061]     When the follower pin  64  is rotated to the position  61 ( 3 ) from the position  61 ( 2 ) of the cam groove of the fixed barrel  61  to extend the rotary barrel  62 , the cam follower  63   b  of the restraining barrel  63  reaches the position  61 ( 13 ) of the cam groove of the fixed barrel  61 . The restraining barrel  65  does not rotate with respect to the rotary barrel  62 . The cam grooves  61   a  and  61   b  are formed on the fixed barrel  61  to equalize the average amount of extension of the angle of the rotary barrel  62  and that of the restraining barrel  63 .  
         [0062]     Thus, the rotary barrel  62 , the restraining barrel  63 , the cam barrel  65 , the forward barrel  67 , the first lens frame  68 , and the second lens frame  70  act integrally, rotating together around the central axis J 2  while extending.  
         [0063]     When the follower pin  64  passes the position  61 ( 13 ) of the cam groove of the fixed barrel  61 , the rotary barrel  62  is smoothly extended since the cam groove  61   b  of the fixed barrel  61  is deeper than the cam groove  61   a . Specifically, although the follower pin  64  does not engage at the side  61 ( 14 ) of the cam groove  61   a  of the fixed barrel  61 , the protrusion  62   b  of the rotary barrel  62  substantially engages with the cam groove  61   a  of the fixed barrel  61 . That is, the follower pin  64  serves as a main guide portion of the cam groove  61   a  of the fixed barrel  61 . The protrusion  62   b  is preferably formed on the rotary barrel  62  to guide the follower pin  64  through the position  61 ( 13 ) of the cam groove of the fixed barrel  61 . When the protrusion  62   b  of the rotary barrel  62  substantially engages the cam groove  61   a  of the fixed barrel  61 , it does not overly limit the follower pin  64 , affecting the guide function thereof.  
         [0064]     When the follower pin  64  reaches the position  61 ( 3 ) of the cam groove of the fixed barrel  61 , and the cam follower  63   b  of the restraining barrel  63  reaches the position  61 ( 13 ) of the cam groove of the fixed barrel  61 , the optical axis J 1  are identical with the central axis J 3  of the first and second lens groups  31  and  32 .  
         [0065]     If the follower pin  64  is continuously rotated to the position  61 ( 4 ) from the position  61 ( 3 ) of the cam groove of the fixed barrel  61  to extend the rotary barrel  62 , the cam follower  63   b  of the restraining barrel  63  moves to the position  61 ( 14 ) from the position  61 ( 13 ) of the cam groove of the fixed barrel  61  along the optical axis direction, similar to the follower pin  64  moving from the position  61 ( 1 ) of the cam groove of the fixed barrel  61  to the position  61 ( 2 ). That is, the restraining barrel  63  rotates with respect to the rotary barrel  62 . The cam follower  65   a  of the cam barrel  65  moves to the position  63 ( 4 ) from the position  63 ( 2 ) of the cam groove of the cam barrel  63 . The cam barrel  65  rotates with respect to the restraining barrel  63 . The follower pin  69  moves to the position  65 ( 4 ) from the position  65 ( 2 ) of the cam groove of the cam barrel  65 . The cam follower  70   a  of the second lens frame  70  is driven to the position  65 ( 14 ) from the position  65 ( 12 ) of the cam groove of the cam barrel  65 , resulting in the photographing state of the lens barrel  2  in minimum zoom state, as shown in  FIG. 1 .  
         [0066]     Zoom operation from the photographing state in minimum zoom state to that in full zoom state is described in the following.  
         [0067]     The rotary barrel  62  is rotated by the zoom gear  83 , and the follower pin  64  is moved from the position  61 ( 4 ) of the cam groove of the fixed barrel  61  until it reaches the position  61 ( 5 ) which represents the photographing state in full zoom state. The position  61 ( 4 ) represents the photographing state in minimum zoom state. Since the cam groove of the fixed barrel  61  at this range is perpendicular to the optical axis direction, the rotary barrel  62  is not extended along the optical axis direction. Thus, the rotary barrel  62  rotates around the axis J 2 , and the restraining barrel  63  is stopped. During this motion, since the restraining barrel  63  rotates with respect to the rotary barrel  62 , the cam follower  65   a  of the cam barrel  65  is moved from the position  63 ( 4 ) of the cam groove of the restraining barrel  63  until it reaches the position  63 ( 5 ). Additionally, since the cam barrel  65  rotates with respect to the restraining barrel  63 , the follower pin  69  is moved from the position  65 ( 4 ) of the cam groove of the cam barrel  65  until it reaches the position  65 ( 5 ), and the cam follower  70   a  of the second lens frame  70  is moved from the position  65 ( 14 ) of the cam groove of the cam barrel  65  until it reaches the position  65 ( 15 ). Since the restraining barrel  63  is stopped, the first lens frame  68 , supporting the first lens group  31 , and the second lens frame  70 , supporting the second lens group  32 , do not rotate around the central axis J 2 , but move forward/backward along the optical axis direction. The cam grooves of the cam barrel  65  and the restraining barrel  63  consecutively adjust focal length between the minimum zoom state and the full zoom state.  FIG. 20  is a cross section of the lens barrel  2  in the photographing state in full zoom state.  
         [0068]     Transition from the photographing state in full zoom state to that in minimum zoom state may be driven by rotating the zoom gear  83  in a reverse direction. The focal length is adjusted by controlling the zoom motor  81  for driving the zoom gear  83 . Additionally, transition from the photographing state in minimum zoom state to that in full zoom state may be driven by rotating the zoom gear  83  in a reverse direction to obtain the lens barrel  2  in the collapsed state as shown in  FIG. 13 .  
         [0069]      FIG. 21  is a graph showing the relationship between angles of the rotary barrel  62  and distance traveled by moving devices of the lens barrel  2  along the optical axis. A transverse axis represents the rotary angle of the rotary barrel  62 . A vertical axis represents absolute moving distance to the rotary barrel  62 , the restraining barrel  63 , the cam barrel  65 , the second lens frame  70 , and the first lens frame  68  in the optical axis direction. In  FIG. 21 , positions of the cam groove through which the moving devices pass in  FIGS. 17-19  are shown. Distance traveled by the moving devices of the lens barrel  2  along the optical axis direction can be seen in  FIG. 21 .  
         [0070]      FIG. 22  is a front view of a shutter unit  71  and a flexible printed circuit board  72 . In  FIG. 22 , the flexible printed circuit board  72  is spread out, and is not assembled in the lens barrel  2 .  FIG. 23  is a cross section of the shutter unit  71  comprising a shutter blade  71   b  and a diaphragm blade  71   c . The shutter blade  71   b  shields a light from the side of the object. The diaphragm blade  71   c  restrains the light from the side of the object. An actuator  71   a  of the shutter unit  71  is connected to the control circuit of the camera via a flexible printed circuit board  72  to drive and control the shutter blade  71   b  and the diaphragm blade  71   c.    
         [0071]      FIG. 24  is a cross section of the shutter unit  71  and the flexible printed circuit board  72  of the lens barrel  2  in the collapsed state. The shutter unit  72  is fixed with respect to the second lens frame  70  in a manner such that a central axis J 5  of an opening  71   d  is identical with the central axis J 3  of the second lens group  32 . A portion  72   d  of the flexible printed circuit board  72  is fixed to a planar portion  67   f  of the forward barrel  67  near the CCD holder  21 . A portion  72   c  of the flexible printed circuit board is fixed to an inner portion  67   g  of the forward barrel  67 . A portion  72   a  of the flexible printed circuit board  72  is fixed to a portion  70   c  of the second lens frame  70 . A portion  72   f  of the flexible printed circuit board  72  is fixed to the flexible printed circuit board  51  by soldering.  
         [0072]      FIG. 25  is a perspective view of the shutter unit  71  and the flexible printed circuit board  72  from an arrow B in  FIG. 24 . In  FIG. 25 , the portions  72   a ,  72   b ,  72   c ,  72   d ,  72   e , and  72   f  of the flexible printed circuit board  72  in  FIG. 22  are in the collapsed state.  
         [0073]     The deflection of the flexible printed circuit board  72  in the lens barrel  2  is described in the following. Since the shutter unit  71  is fixed to the second lens frame  70 , it can also be driven by the driving mechanism of the lens barrel  2 . The forward barrel  67  serves as a restraint member to restrain the rotation of the shutter unit  71  without restraining the movement of the shutter unit  71  in the optical axis direction. That is, the forward barrel  67  brings the shutter unit  71  rotating around the central axis of the lens barrel  2 , and restrains the rotation of the shutter unit  71 .  
         [0074]     When the lens barrel is extended from the collapsed state to the photographing state in minimum zoom state, the forward barrel  67  and the second lens frame  70  move toward the optical axis direction while rotating around the central axis J 2  of the lens barrel  2 . Since the portion  72   f  of the flexible printed circuit board  72  is fixed and the portion  72   d  thereof is extended along with the forward barrel  67 , the portion  72   e  is deflected in the rotary direction.  FIG. 26  is a schematic view of the above motion from an arrow C in  FIG. 25 . In  FIG. 26 , the solid line represents the state in the collapsed state, and the dotted line represents the state in the photographing state in minimum zoom state. Since the forward barrel  67  is moved and rotated as shown by arrow D, the portion  72   e  of the flexible printed circuit board  72  is deflected as shown in  FIG. 26  to offset the distance of the movement of the shutter unit  71  in the rotary direction. That is, the portion  72   e  is bendable so as to provide a variable length for the rotation of the shutter unit  71  around a rotary axis parallel with the optical axis.  
         [0075]      FIG. 27  is a cross section of the shutter unit  71  and the flexible printed circuit board  72  in the lens barrel  2  in the photographing state in minimum zoom state.  FIG. 28  is a perspective view of the shutter unit  71  and the flexible printed circuit board  72  from an arrow E in  FIG. 27 . When the lens barrel  2  is extended from the collapsed state to the photographing state in minimum zoom state, the second lens frame  70  is moved with respect to the forward barrel  67  in the optical axis direction. Since the portion  72   e  of the flexible printed circuit board  72  is fixed to the forward barrel  67  and the portion  72   a  thereof is fixed to the second lens frame  70 , the portion  72   b  is deflected from the state in  FIG. 24  to the state in  FIG. 27  to offset the distance of the movement of the shutter unit  71  in the optical axis direction. That is, the portion  72   b  is foldable so as to provide a variable length for the movement of the shutter unit  71  in the optical axis.  
         [0076]     In the photographing state, when the lens barrel  2  zooms from the minimum zoom state to the full zoom state, the shutter unit  71  fixed to the second lens frame  70  is moved in the optical axis direction with respect to the forward barrel  67 .  FIG. 29  is a cross section of the shutter unit  71  and the flexible printed circuit board  72  in the lens barrel  2  in the photographing state in full zoom state. During zooming, the portion  72   b  of the flexible printed circuit board  72  is deflected from the state in  FIG. 27  to the state in  FIG. 29  to offset the distance of the movement of the shutter unit  71  in the optical axis direction.  
         [0077]     As previously described, when the shutter unit  71  is rotated around the central axis J 2  of the lens barrel  2 , its movement is offset by the deflection of the portion  72   e  of the flexible circuit board  72 . When the shutter unit  71  is moved in the optical axis direction with respect to the forward barrel  67 , its movement is offset by the deflection of the portion  72   b  of the flexible circuit board  72 .  
         [0078]     Since the second lens frame  70  and the shutter unit  71  can be rotated around the central axis of the lens barrel  2  such that the lens barrel  2  is collapsed, a thinner lens barrel can be obtained.  
         [0079]     While the lens barrel is described as above, it is not limited thereto, and may include various embodiments.  
         [0080]     For example, while the central axis J 2  of the lens barrel  2  is eccentric from the optical axis J 1  in this embodiment, it is not limited thereto, and may be identical.  
         [0081]     While the portions  72   c  and  72   d  of the flexible printed circuit board  72  are fixed to the forward barrel  67  in this embodiment, they are not limited thereto, and may be fixed to the restraint barrel  63  that is also a restraint member for the shutter unit  71 .  
         [0082]     While the shutter unit  71  is fixed to the second lens frame  70  in this embodiment, it is not limited thereto, and may be fixed to another lens frame. Moreover, the shutter unit may rotate and move independently.  
         [0083]     While the lens barrel is provided with a zooming function in this embodiment, it is not limited thereto, and may not be provided with zooming motion, such as a single focus lens barrel.  
         [0084]     Since the shutter unit moves freely in the lens barrel, a thinner camera with good portability can be obtained. Thus, such a lens barrel can be widely applied in the digital cameras.  
         [0085]     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.