Patent Publication Number: US-2017351055-A1

Title: Lens barrel, image capturing device and method of manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of U.S. patent application Ser. No. 14/466,607 filed on Aug. 22, 2014, which in turn is a continuation application of PCT/JP2013/054544 filed on Feb. 22, 2013, which claims priority to Japanese Patent Application No. 2012-042479 filed on Feb. 28, 2012, the contents of which are herein wholly incorporated by reference. 
    
    
     FIELD 
     A certain aspect of the embodiments discussed herein is related to a lens barrel, an image capturing device and a method of manufacturing the same. 
     BACKGROUND 
     Conventionally, an lens barrel to be attached to a camera includes: a fixed cylinder that is fixed to the camera in a state where it is attached to the camera; a cam cylinder that rotates about the fixed cylinder; and a plurality of lens groups that move in an optical axis direction by the rotation of the cam cylinder (e.g., see Japanese Laid-open Patent Publication No. 2000-89086). 
     On a design, such a lens barrel has various restrictions in order to secure optical performance. It is desirable to simplify the structure in the lens barrel, in order to secure the optical performance under the restrictions. 
     SUMMARY 
     According to an aspect of the present invention, there is provided a lens barrel of the present invention includes: a first cylindrical member that extends in a prescribed axial direction; a second cylindrical member that slides in the prescribed axial direction along an inner circumferential surface of the first cylindrical member; an axis member that slides in the prescribed axial direction along an inner circumferential surface of the second cylindrical member; and a first holding member that is fixed to the axis member, is guided in the prescribed axial direction by the slide of the axis member against the second cylindrical member, and holds a first optical member. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory am: are no restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating the configuration of a camera according to an embodiment; 
         FIG. 2  is a cross-section diagram illustrating a lens barrel (a state where the lens barrel is placed at a wide angle end); 
         FIG. 3  is a cross-section diagram illustrating the lens barrel (a state where the lens barrel is placed at a telephoto end); 
         FIG. 4  is a diagram abstracting and illustrating a second group lens sliding cylinder, a third group lens sliding cylinder and the vicinity of them; 
         FIG. 5A  is a cross-section diagram taken along a line A-A in  FIG. 4 ; 
         FIG. 5B  is a cross-section diagram taken along a line B-B in  FIG. 4 ; 
         FIG. 6  is a diagram abstracting and illustrating a fourth and sixth group lens sliding cylinder, a fifth group lens sliding cylinder and the vicinity of them; 
         FIG. 7  is a diagram illustrating a state where the second group lens sliding cylinder and the third group lens sliding cylinder move forward from a state of  FIG. 4 ; 
         FIG. 8A  is a diagram explaining a variation example 1; 
         FIG. 8B  is a cross-section diagram taken along a line C-C in  FIG. 8A ; 
         FIG. 9A  is a diagram explaining a variation example 2; 
         FIG. 9B  is a cross-section diagram taken along a line D-D in  FIG. 9A ; 
       FIG,  10 A is a diagram explaining a variation example 3; 
         FIG. 10B  is a diagram explaining a variation example 4; and 
         FIG. 11  is a diagram explaining a variation example 5. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a detailed description will be given of a camera and a lens barrel with which the camera is provided, according to an embodiment, based on  FIGS. 1 to 7 . 
     In  FIG. 1 , a camera  500  according to the present embodiment is schematically illustrated. As illustrated in  FIG. 1 , the camera  500  includes an image capturing unit  200  and a lens barrel  100 . 
     The image capturing unit  200  includes: a chassis  210 ; an optical system including a main mirror  212 , a pentaprism  214  and an eyepiece optical system  216 ; a focus detector  230 ; a shutter  234 ; an image capturing element  238 ; a main LCD  240 ; and a main controller  250  which are housed in the chassis  210 . 
     In the state of  FIG. 1 , the main mirror  212  leads most of an incident light made incident from the lens barrel  100  to a focusing screen  222  arranged on the upper side. The focusing screen  222  is arranged at a focusing position of the optical system in the lens barrel  100 , and provides an image formed by the optical system in the lens barrel  100 . 
     The pentaprism  214  reflects an image formed on the focusing screen  222 , and then leads the reflected image to the eyepiece optical system  216  via a half mirror  224 . Thereby, in the eyepiece optical system  216 , the operator can observe the image on the focusing screen  222  as an erect image. In this case, the half mirror  224  superimposes a display image indicating a photographing condition, a setting condition and so on formed on a finder LCD  226 , onto the image of the focusing screen  222 . Therefore, in an exit end of the eyepiece optical system  216 , the operator can observe a state where the image of the finder LCD  226  is superimposed on the image of the focusing screen  222 . Here, a part of an emitted light of the pentaprism  214  is led to a photometry unit  228 , and the intensity of the incident light, its distribution, and so on are measured by the photometry unit  228 . 
     The focus detector  230  detects a focus adjustment state (i.e., focus state) of the optical system in the lens barrel  100  by using a light which penetrates the main mirror  212  and is reflected with a sub-mirror  232  provided on the back side of the main mirror  212 . Here, in the case of photographing, the main mirror  212  and the sub-mirror  232  go up to a position illustrated in  FIG. 1  with a dashed line so that they evacuate from an optical path of the incident light which enters from the lens barrel  100 . 
     The shutter  234  is arranged behind the main mirror  212  (i.e., a rear side of the optical path of the incident light which enters from the lens barrel  100 ). In the case of photographing, the shutter  234  performs open operation in conjunction with the rising operation of the main mirror  212  and the sub-mirror  232 . In a state where the shutter  234  is opened, the incident light from the lens barrel  100  enters into the image capturing element  238  via an optical filter  236 . The image capturing element  238  converts the image formed by the incident light, into an electrical signal. 
     A display screen portion of the main LCD  240  is in a state exposed to the exterior of the chassis  210 . Various setting information in the image capturing unit  200  in addition to the image (i.e., a photographed image) formed on the image capturing element  238  are displayed on the display screen of this main LCD  240 . 
     The main controller  250  generally controls various operation of each element mentioned above. Moreover, the main controller  250  drives the optical system (e,g. lenses L 1  to L 6 ) in the lens barrel  100  (i.e., autofocus) with reference to the information on the focus adjustment state of the optical system which the focus detector  230  in the image capturing unit  200  detects, and displays the execution of the focusing on the finder LCD  226  (i.e., focus aid) with reference to an operation amount of the optical system in the lens barrel  100 . 
     Next, a detailed description will be given of the configuration of the lens barrel  100  based on  FIGS. 2 to 7 . 
     Cross-section diagrams of the lens barrel  100  are illustrated in  FIGS. 2 and 3 . In these drawings,  FIG. 2  illustrates a state where the lens barrel  100  is placed at a wide angle end, and  FIG. 3  illustrates a state where the lens barrel  100  is zoomed to a telephoto end. As illustrated in  FIGS. 2  arid  3 , the lens barrel  100  includes a first group lens L 1 , a second group lens L 2 , a third group lens L 3 , a fourth group lens L 4 , a fifth group lens L 5  and a sixth group lens L 6  which are arranged on a common optical axis AX. In the following description, it is assumed that a side of the first group lens L 1  (i.e., an objection side) in an optical axis AX direction is a front side, and a side of the sixth group lens L 6  (i.e., an image side) in the optical axis AX direction is a rear side. 
     As illustrated in  FIGS. 2 and 3 , the lens barrel  100  includes: a fixed cylinder  10 ; a first group lens sliding cylinder  11  that holds the first group lens L 1 ; a second group lens sliding cylinder  12  that holds the second group lens L 2 ; a third group lens sliding cylinder  13  that holds the third group lens L 3 ; a fourth and sixth group lens sliding cylinder  14  that holds the fourth group lens L 4  and the sixth group lens L 6 ; and a fifth group lens sliding cylinder  15  that holds the fifth group lens L 5 . 
     The fixed cylinder  10  is fixed to the image capturing unit  200  at a base unit  10   a.  In the fixed state, an end face  10   b  of the fixed cylinder  10  on the side of the image capturing unit  200  comes in close contact with the image capturing unit  200  (i.e., the chassis  210  of  FIG. 1 ), so that the fixed cylinder  10 , i.e., the lens barrel  100  is positioned to the image capturing unit  200 . In the fixed cylinder  10 , a pair of projecting portions  33   a  and  33   b  provided near an upper portion (i.e., a ceiling portion) inside the fixed cylinder  10  support a guide pipe  36 A, and a pair of projecting portions  33   c  and  33   d  provided near a lower portion inside the fixed cylinder  10  support a guide pipe  36 B. The guide pipes  36 A and  36 B are arranged at the positions (i.e., positions in which the distances from the optical axis are approximately the same as each other, and the positions which are opposed to each other and sandwich the optical axis) which are opposed to each other at 180 degrees on the basis of the optical axis AX of the lens barrel  100 . A guide pipe  35 A is inserted in the inside of the guide pipe  36 A (i.e., the guide pipes have double structure). The outside diameter of the guide pipe  35 A is set to have almost the same as the inside diameter of the guide pipe  36 A. Here, the term “almost the same diameters” means sizes in which a gap of the degree that the slide of the guide pipe  35 A does not have a trouble is formed between the guide pipe  36 A and the guide pipe  35 A. Thereby, the guide pipe  35 A can perform sliding movement along the inner circumferential surface of the guide pipe  36 A. Here, stainless steel with high intensity and lightweight can be adopted as a material of the guide pipes  36 A and  36 B and the guide pipe  35 A. 
     The first group lens sliding cylinder  11  is interlockably coupled with a zoom driving cylinder  16  provided inside the first group lens sliding cylinder  11 . Specifically, a cam pin  75  implanted in the first group lens sliding cylinder  11  is in a state of engaging with a cam groove  16   a  formed on the zoom driving cylinder  16 . 
     On the contrary, in the outermost circumference of the lens barrel  100 , the zoom driving cylinder  16  is interlockably coupled with a zoom operation ring  18  which can rotate about the optical axis AX. Specifically, a driving force transfer pin  19  projected outward from the zoom driving cylinder  16  engages with an operation groove  18   a  which is formed on the inner circumference of the zoom operation ring  18  and is in parallel with the optical axis AX. Thereby, the zoom driving cylinder  16  rotates in conjunction with the rotation of the zoom operation ring  18 . The zoom operation ring  18  cannot move in a front-back direction, and an antiskid rubber layer is provided on an outer circumferential surface of the zoom operation ring  18 . The zoom operation ring  18  is rotated by a user in the case of variable power operation (zooming). 
     The zoom driving cylinder  16  can rotate against a zoom guidance cylinder  22  provided in the inside of the zoom driving cylinder  16 . As illustrated in the lower half of  FIGS. 2 and 3 , a cam groove  22   a  is pierced and formed on the zoom guidance cylinder  22 . A rotation coupling member  21  fixed to the earn ring  20  provided in the inside of the fixed cylinder  10  engages with the zoom guidance cylinder  22  and a straight groove  16   b  which is pierced and formed on the zoom driving cylinder  16 . 
     According to the above-mentioned structure, when the zoom operation ring  18  is rotated, the zoom driving cylinder  16  rotates by the action of the driving force transfer pin  19 , and the first group lens sliding cylinder  11  moves in the front-back direction (i.e., the direction along the optical axis AX) by the rotation of the zoom driving cylinder  16  and the action of the cam pin  75 . When the zoom driving cylinder  16  rotates by the rotation of the zoom operation ring  18 , the torque is transmitted to the cam ring  20  via the rotation coupling member  21 , and hence the cam ring  20  moves in the front-back direction while rotating. Here, the zoom guidance cylinder  22  moves in the front-back direction without rotating. 
     Here, a cover cylinder  17  is provided between the zoom operation ring  18  and the first group lens sliding cylinder  11 . As illustrated in  FIGS. 2 and 3 , the cover cylinder  17  moves in the front-back direction along with the first group lens sliding cylinder  11 , seals between the zoom operation ring  18  and the first group lens sliding cylinder  11 , and prevents the invasion of dust into the lens barrel  100 . 
       FIG. 4  is a diagram abstracting and illustrating the second group lens sliding cylinder  12 , the third group lens sliding cylinder  13  and the vicinity of them. As illustrated in  FIG. 4 , the second group lens sliding cylinder  12  includes: a holding cylinder  24  that holds the second group lens L 2 ; a holding ring  26  that is fixed to the holding cylinder  24 ; and an engaging cylinder  28  that is provided in the state of surrounding the outer circumference of the holding cylinder  24 . The holding cylinder  24  and the holding ring  26  are fixed by a screw fastening, and hold an outer edge portion of the second group lens L 2 . 
     The engaging cylinder  28  performs cantilever support of two guide bars  30 A and  30 B. The two guide bars  30 A and  30 B sandwich the optical axis AX and are arranged at vertically symmetrical positions (i.e., positions which is opposed to each other at 180 degrees). 
     The guide bar  30 A is a cylindrical member slidably inserted into the guide pipe  35 A that is inserted into the guide pipe  36 A, as illustrated in  FIG. 4 . The outside diameter of the guide bar  30 A is set to have almost the same as the inside diameter of the guide pipe  35 A. Here, the term “almost the same diameters” means sizes in which a gap of the degree that the slide of the guide bar  30 A does not have a trouble is formed between the guide pipe  35 A and the guide bar  30 A. Here, it is not necessary to carry out surface contact between the guide bar  30 A and the guide pipe  35 A, and point contact between the guide bar  30 A and the guide pipe  35 A may only be carried out at two points near one end and another end of the guide pipe  36 A. 
     The guide bar  30 B is a cylindrical member which is in the state inserted in the guide pipe  36 B via an elliptic hole  43  which is pierced and formed on the projecting portion  33   c,  as illustrated in  FIG. 4 . A cross-section diagram taken along a line A-A in  FIG. 4  is illustrated in  FIG. 5A . As illustrated in  FIG. 5A , the diameter of the section of the guide bar  30 B is set to have almost the same as the width of the elliptic hole  43  (the width of the horizontal direction of the paper surface in  FIG. 5A ), i.e., to a size of the degree that the slide of the guide bar  30 B does not have a trouble. The movement of the second group lens sliding cylinder  12  in a rotational direction around the guide bar  30 A is controlled by the contact of the guide bar  30 B and the inner circumferential surface of the elliptic hole  43 . Here, as illustrated in  FIG. 5A , the inside diameter of the guide pipe  36 B is set larger than the guide bar  30 B, and a gap is secured between the guide pipe  36 B and the guide bar  30 B (the guide bar  30 B and the guide pipe  36 B are non-contact). 
     Here, a material with high intensity and lightweight, such as stainless steel, can be adopted as a material of the guide bars  30 A and  30 B, as with the guide pipes  36 A,  36 B and  35 A. The guide bars  30 A and  30 B are fixed to the engaging cylinder  28  through processing of adhesion or press-fitting. 
     A projection-shaped follower  28   a  is formed on a part of the outer circumferential surface of the engaging cylinder  28 , as illustrated in  FIG. 4 . The follower  28   a  engages with a circumferential groove  32   c  of an interlocking ring  32  provided outside the engaging cylinder  28 , as illustrated in  FIG. 2 . Here, the follower  28   a  is arranged near the guide bar  30 A, i.e., near an extension axis which extends a central axis of the guide bar  30 A. 
     Moreover, an interlocking groove  32   a  and a cam follower  32   b  are formed on the interlocking ring  32  on which the circumferential groove  32   c  is formed. One end portion of an interlocking key  34  having a substantial L-shape engages with the interlocking groove  32   a.  The interlocking key  34  is connected to a focus ring  37  provided on an outer circumferential unit of the fixed cylinder  10 , and moves in a rotational direction around the optical axis AX in accordance with the rotation of the focus ring  37  around the optical axis AX. Thus, the interlocking key  34  moves in the rotational direction around the optical axis AX, so that the interlocking ring  32  rotates about the optical axis AX. The interlocking key  34  is connected also to a motor  38  provided in a motor room  10   c  of the fixed cylinder  10 . Therefore, the interlocking ring  32  rotates about the optical axis AX by also the movement of the interlocking key  34  in the rotational direction around the optical axis AX along with the rotational operation of the motor  38 . 
     The cam follower  32   b  engages with a cam groove  20   b  formed on the cam ring  20 . Therefore, when the interlocking ring  32  rotates, the interlocking ring  32  and members (i.e., the second group lens sliding cylinder  12 , the guide bars  30 A and  30 B, and the second group lens L 2 ) coupled with the interlocking ring  32  move in the front-back direction by the action of the cam groove  20   b  and the cam follower  32   b.  In the movement of the front-back direction, the interlocking ring  32  moves in the front-back direction while rotating about the optical axis AX. Since the moving direction of the guide bar  30 A is only the front-back direction by the guide pipes  35 A and  36 A, the second group lens sliding cylinder  12  and the second group lens L 2  which are connected to the guide bar  30 A move in the front-back direction without rotating about the optical axis. Here, the cam follower  32   b  is arranged near the guide bar  30 A, i.e., near the extension axis which extends the central axis of the guide bar  30 A. 
     The third group lens sliding cylinder  13  includes a circular hole  13   a  and an elliptic hole  13   b,  as illustrated in.  FIG. 4 . 
     The inner diameter of the circular hole  13   a  is the same as the outer diameter of the guide pipe  35 A. The third group lens sliding cylinder  13  holds the guide pipe  35 A in a state where the guide pipe  35 A is inserted in the circular hole  13   a.  In this case, the guide pipe  35 A is fixed to the third group lens sliding cylinder  13  through processing of adhesion or press-fitting. 
     The elliptic hole  13   b  has an elliptic shape, as illustrated in  FIG. 5B  which is a cross-section diagram taken along a line B-B in  FIG. 4 . The width of the elliptic hole  13   b  (the width of the horizontal direction of the paper surface in  FIG. 5B ) is set to have almost the same as the diameter of the guide bar  30 B, i.e., to a size of the degree that the slide of the third group lens sliding cylinder  13  does not have a trouble. The movement in the rotational direction around the guide pipe  35 A of the third group lens sliding cylinder  13  is controlled by the contact of the guide bar  30 B and the inner circumferential surface of the elliptic hole  13   b.  Here, a cross-sectional U-shaped groove having the same function as the ellipse hole  13   b  may be formed on the third group lens sliding cylinder  13 , instead of the ellipse hole  13   b.    
     Moreover, a cam follower  13   c  is provided near the circular hole  13   a  of the third group lens sliding cylinder  13 , as illustrated in  FIG. 2 . The cam follower  13   c  engages with a cam groove  20   d  formed on the cam ring  20 . Therefore, when the cam ring  20  rotates, the third group lens sliding cylinder  13  moves in the front-back direction by the action of the cam groove  20   d  and the cam follower  13   c . Since the moving direction of the guide pipe  35 A is only the front-back direction by the guide pipes  36 A in the movement of the front-back direction, the third group lens sliding cylinder  13  and the third group lens L 3  which are connected to the guide pipe  35 A move in the front-back direction without rotating. 
       FIG. 6  is a diagram abstracting and illustrating the fourth and sixth group lens sliding cylinder  14 , the fifth group lens sliding cylinder  15  and the vicinity of them. As illustrated in  FIG. 6 , the fourth and sixth group lens sliding cylinder  14  holds the fourth group lens L 4  and the sixth group lens L 6  in a state where the lenses L 4  and L 6  are separated in a direction of the optical axis AX by a predetermined interval. The fifth group lens sliding cylinder  15  holds the fifth group lens L 5  between the fourth group lens L 4  and the sixth group lens L 6 . 
     The fourth and sixth group lens sliding cylinder  14  includes engaging units  14   a  and  14   b  that engages with the guide pipe  36 A, and an engaging unit  14   c  that engages with the guide pipe  36 B. Moreover, the fifth group tens sliding cylinder  15  includes engaging units  15   a  and  15   b  that engages with the guide pipe  36 A, and an engaging unit  15   c  that engages with the guide pipe  36 B. 
     Each of engaging units  14   a ,  14   b,    15   a  and  15   b  has a circular through-hole. The through-hole has almost the same diameter as the guide pipe  36 A. The fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15  are guided in the front-back direction by the guide pipe  36 E in a state where the guide pipe  36 A is inserted into the through-holes. Here, the term “almost the same diameter” means sizes in which a gap of the degree that the slide of the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15  does not have a trouble is formed between guide pipe  36 A and each of the through-holes. The guide pipe  36 A supports all the weight or at least a half of all the weight (i.e., the weight changes by a posture of the lens barrel  100 ) of the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15 . On the other hand, each of engaging units  14   c  and  15   c  has a U-shaped groove. The width of the U-shaped groove is set to have almost the same as the diameter of the guide pipe  36 B, i.e., to a size of the degree that the slide of the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15  does not have a trouble. The movement in the rotational direction around the guide pipe  36 A of the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15  is controlled by the contact of the guide pipe  36 B and the engaging units  14   c  and  15   c.  Here, an ellipse hole which is long in a radial direction and has the same function as the U-shaped groove may be formed on each of the engaging units  14   c  and  15   c,  instead of the U-shaped groove. 
     Here, the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15  are driven in the front-back direction (i.e., the direction of the optical axis AX) in conjunction with the rotational movement around the optical axis AX of the cam ring  20 . 
     Next, a description will be given of the moving operation of each of the lens L 1  to L 6  when the noon operation (zooming) is performed and the moving operation of each of the lens L 1  to L 6  when the focus adjustment (focusing) is performed, based on  FIGS. 2 and 3 . 
     First, a description will be given of the moving operation of each lens in the case of zooming. Here, a description will be given of operation of the lens barrel  100  zoomed from the wide angle end ( FIG. 2 ) to the telephoto end ( FIG. 3 ). 
     When the zoom operation ring  18  is rotated by a user from the state of  FIG. 2 , the zoom driving cylinder  16  rotates and the first group lens sliding cylinder  11  and the first group lens L 1  go straight forward via the cam groove  16   a  and the cam pin  75 . Moreover, when the zoom operation ring  18  is rotated, the cam ring  20  is rotated via the rotation coupling member  21  as described above. With this rotation, the torque and the moving force in the front direction act on also the interlocking ring  32  via the cam follower  32   b.  However, since the interlocking ring  32  is guided only in the front-back direction by the interlocking key  34  (fixed state) which engages with the interlocking groove  32   a,  the interlocking ring  32  goes straight forward without rotating. With going straight of this interlocking ring  32 , the second group lens L 2  and the engaging cylinder  28  (i.e., the second group lens sliding cylinder  12 ) which engages with the interlocking ring  32  move forward. Moreover, the third group lens L 3  and the third group lens sliding cylinder  13  which engages with the cam ring  20  move forward. 
     In addition, the rotation of the cam ring  20  also moves the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15  (the fourth group lens L 4  to the sixth group lens L 6 ) forward. 
     Thus, in the ease of zooming, each of the first group lens L 1  to the sixth group lens L 6  moves forward by a discrete distance with the rotational operation of the zoom operation ring  18  (here, the lenses L 4  and L 6  move by the same distance). 
       FIG. 7  illustrates a state where the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  move forward from the state of  FIG. 4 . Even if the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  move forward, the guide bar  30 B keeps maintaining a state of contacting with the projecting portion  33   c  (the elliptic hole  43 ) and the third group lens sliding cylinder  13  (the ellipse hole  13   b ), as illustrated in.  FIG. 7 . The guide bar  30 A keeps maintaining an insertion state to the guide pipe  35 A, and the guide pipe  35 A keeps maintaining an insertion state to the guide pipe  36 A. 
     Next, a description will be given of the moving operation of each lens in the case of focusing. 
     First, the focus ring  37  is rotated by the user or the motor  38  is rotationally driven, so that the interlocking key  34  moves in the rotational direction around the optical axis AX, and the interlocking ring  32  which engages with the interlocking key  34  rotates about the optical axis AX, as described above. By this rotation, the interlocking ring  32  arranges the cam follower  32   b  along the cam groove  20   b  of the cam ring  20 , and also moves forward. By the movement of this interlocking ring  32  the rotational direction and the front direction, the second group lens L 2  and the engaging cylinder  28  (i.e., the second group lens sliding cylinder  12 ) having the follower  28   a  which engages with the circumferential groove  32   c  of the interlocking ring  32  move forward. Here, since the cam follower  32   b  and the follower  28   a  are arranged near the guide bar  30 A, the cam follower  32   b  and the follower  28   a  can make a driving force in the optical axis AX direction efficiently act on the interlocking ring  32  and the engaging cylinder  28 . 
     On the other hand, since the cam ring  20  is in a fixed state of no rotation, the first group lens L 1  and the third group lens L 3  to the sixth group lens L 6  do not move in the front-back direction. 
     Thus, in the case of focusing, only the second group lens L 2  moves in the front (back) direction with the rotational direction of the interlocking key  34 . 
     Here, the main controller  250  of  FIG. 1  controls the rotation of the motor  38  in the case of focusing based on a detection result of the focus detector  230 . That is, the autofocus is performed according to the rotational control of the motor  38  by the main controller  250 . Here, the lens barrel  100  and the image capturing unit  200  are electrically connected by a connection terminal provided therebetween. Thereby, an electric power is supplied to the lens barrel  100  (e.g. the motor  38 ) from a side of the image capturing unit  200 . 
     As described above in detail, according to the present embodiment, the guide pipe  35 A slides in the direction of the optical axis AX along the inner circumferential surface of the guide pipe  36 A fixed to the fixed cylinder  10 , and the guide bar  30 A slides in the direction of the optical axis AX along the inner circumferential surface of the guide pipe  35 A. Further, the second group lens sliding cylinder  12  which holds the second group lens L 2  is fixed to the guide bar  30 A and is guided in the optical axis direction by the slide of the guide bar  30 A. The third group lens sliding cylinder  13  which holds the third group lens L 3  is fixed to the guide pipe  35 A and is guided in the optical axis direction by the slide of the guide bar  30 A. Thus, in the present embodiment, the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  can be separately guided with the guide pipes  35 A and  36 A having the double structure, and the guide bar  30 A, and hence it is possible to simplify the structure in the lens barrel  100 . Thereby, the space efficiency in the lens barrel  100  can be improved, and the lens barrel  100  can be downsized (the increment of the diameter can be controlled). Moreover, the whole camera  500  can also be downsized by downsizing the lens barrel  100 . 
     Moreover, in the present embodiment, the guide bar  30 B extending in the direction of the optical axis AX is fixed to the second group lens sliding cylinder  12  and contacts with the third group lens sliding cylinder  13  and the fixed cylinder  10 , so that the moving operation (i.e., the rotational operation) of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  around the optical axis AX against the fixed cylinder  10  is controlled. Thereby, since the rotational operation of the two lens sliding cylinders  12  and  13  can be controlled with the one guide bar  30 B, also from this point, the structure in the lens barrel  100  can be simplified and the space efficiency in the lens barrel  100  can be improved. 
     Moreover, in the present embodiment, the fixed cylinder  10  holds the guide pipe  36 B extending in the direction of the optical axis AX. The fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15  are guided in the optical axis direction by the guide pipe  36 A, and contact with the guide pipe  36 B, so that the moving operation (i.e., the rotational operation) around the optical axis is controlled. Thereby, the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15  are guided in the front-back direction in a state of not contacting with the guide bars  30 A and  30 B and the guide pipe  35 A. Therefore, the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15  do not disturb the movement of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13 . Thereby, a force required to move the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  can be reduced, and hence the load of the motor  38  or the load of the user rotating the focus ring  37  can be reduced. 
     Moreover, in the present embodiment, since the guide bar  30 B is inserted inside the guide pipe  36 B, the mechanical interference of the guide pipe  36 B and the guide bar  30 B can be avoided. As compared with the case where the guide pipe  36 B and the guide bar  30 B are provided separately, the structure in the lens barrel  100  can be simplified and the space efficiency in the lens barrel  100  can be improved. 
     Moreover, in the present embodiment, the guide pipes  35 A and  36 A having the double structure support all the weight or at least a half of all the weight (i.e., the weight changes by a posture of the lens barrel  100 ) of the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15 . Thus, at least a half of all the weight of the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15  is supported by the guide pipes  35 A and  36 A in which the rigidity is high and the modification is controlled, and hence an optical axis deviation of the fourth group lens L 4  to the sixth group lens L 6  can be controlled. 
     Moreover, in the present embodiment, since the guide bar  30 A and the guide pipes  35 A and  35 B have the almost same length, it is possible to lengthen a distance in which the guide pipe  35 A guides the guide bar  30 A and a distance in which the guide pipe  36 A guides the guide pipe  35 A. Thereby, the movement length of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  can be lengthened. Moreover, in the present embodiment, since the double structure by the guide pipes  35 A and  36 A is adopted, a movement amount of the second group lens sliding cylinder  12  is a distance in which a movement amount of the third group lens sliding cylinder  13  is added to the length of guide bar  30 A. Thereby, it is possible to lengthen the movement amount of the second group lens sliding cylinder  12 . 
     Moreover, in the present embodiment, since the guide pipes  36 A and  36 B are arranged at the positions which are opposed to each other at 180 degrees on the basis of the optical axis AX of the lens barrel  100 , the distance between the guide bars  30 A and  30 B can be enlarged as much as possible. Thereby, a force required when the rotation around the optical axis AX of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  is controlled by the guide bar  30 B can be made small, and hence the modification, a force applied to the guide bar  30 B, or the like can be made small. 
     Moreover, in the present embodiment, since the guide bar  30 B can be made shorter than the guide bar  30 A, the weight of the lens barrel  100  can be reduced, compared with the case where the guide bar  30 B is the same length as the guide bar  30 A. 
     Moreover, in the above-mentioned embodiment, the description is given of the case where the guide bar  30 B fixed to the second group lens sliding cylinder  12  contacts with the elliptic hole  43  formed on the projecting portion  33   c  of the fixed cylinder  10  and the elliptic hole  13   b  of the third group lens sliding cylinder  13 , and hence the rotational operation of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  is controlled. However, a control method of the rotational operation of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  is not limited to this. The rotational operation of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  may be controlled by adopting the configuration (i.e., variation examples 1 to 5) as illustrated in  FIGS. 8A to 11 . 
     The configuration according to the variation example  1  is illustrated in  FIGS. 8A and 8B . Here,  FIG. 8B  is a cross-section diagram taken along a line C-C in FIG.  8 A. In the variation example  1 , a cap-shaped member  71  on which an elliptic hole  71   a  is formed is provided at a part (i.e., a front end portion) of the guide pipe  36 B. Also in this way, since the guide bar  30 B keeps contacting with the cap-shaped member  71  (i.e., the elliptic hole  71   a ) and the third group lens sliding cylinder  13  (i.e., the elliptic hole  13   b ), it is possible to control the rotational operation of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13 , as with the above-mentioned embodiment. 
     The configuration according to the variation example  2  is illustrated in  FIGS. 9A and 9B . Here,  FIG. 9B  is a cross-section diagram taken along a line D-D in  FIG. 9A . In the variation example 2, a guide pipe  36 B′ having a flat shape in whole is adopted instead of the guide pipe  36 B of the above-mentioned embodiment. Also in this way, since the guide bar  30 B keeps contacting with a part of the inner circumferential surface of the guide pipe  36 B′, it is possible to control the rotational operation of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13 , as with the above-mentioned embodiment. Here, even when the guide pipe  36 B′ having the flat shape is adopted, a problem does not arise in the moving operation of the fourth and sixth group lens sliding cylinder  14  and the fifth group lens sliding cylinder  15 . 
     The configuration according to the variation example 3 is illustrated in  FIG. 10A . In the variation example 3, the guide bar  30 B is fixed to the projecting portion  33   c  of the fixed cylinder  10 . Moreover, in the variation example 3, a U-shaped groove  28   h  is provided in the engaging cylinder  28  of the second group lens sliding cylinder  12 . In this case, while the second group lens sliding cylinder  12  is moving in the front-back direction, the guide bar  30 B keeps contacting with the U-shaped groove  28   h.  Even when such a variation example 3 is adopted, it is possible to control the rotational operation of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13 , as with the above-mentioned embodiment. Here, an elliptic hole having the same function as the U-shaped groove may be formed on the engaging cylinder  28  instead of the U-shaped groove  28   h.  Further, although the guide pipe  36 B is adopted in  FIG. 10A , the variation example is not limited to this. The guide pipe  36 B may be changed to a bar-shaped member (i.e., a guide bar)  36 B″, as illustrated in the variation example  4  of  FIG. 10B . 
     The configuration according to the variation example  5  is illustrated in  FIG. 11 . In the variation example  5 , the guide bar  30 B is fixed to (or held by) the third group lens sliding cylinder  13 . In addition, in the variation example  5 , the U-shaped groove  28   h  is provided in the engaging cylinder  28  of the second group lens sliding cylinder  12 . In this case, while the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13  are moving in the front-back direction, the guide bar  30 B keeps contacting with the U-shaped groove  28   h  and the elliptic hole  43 . Even when the variation example 5 is adopted, it is possible to control the rotational operation of the second group lens sliding cylinder  12  and the third group lens sliding cylinder  13 , as with the above-mentioned embodiment. 
     Here, the above-mentioned embodiments and the variation examples 1 to 5 can be combined in various ways. 
     Moreover, although in the above-mentioned embodiment, the description is given of the case where the guide pipes are the double structure, the guide pipes are not limited to this. The guide pipes may be equal to or more than triplicity. In this case, a lens sliding cylinder can be fixed to each guide pipe. 
     Moreover, although in the above-mentioned embodiment, the description is given of the case where the guide bar  30 B and the guide pipe  36 B are arranged on the same axis, the arrangement of the guide bar  30 B and the guide pipe  36 B is not limited to this. The guide bar  30 B and the guide pipe  36 B may be arranged on different axes, respectively. In this case, the bar-shaped member (i.e., the member as indicated by a code “ 36 ” in  FIG. 10B ) may be used instead of the guide pipe  36 B. 
     Moreover, although in the above-mentioned embodiment, the description is given of the case where all of the first group lens L 1  to the sixth group lens L 6  move in the direction of the optical axis AX in the case of zooming and only the second group lens L 2  moves in the direction of the optical axis AX in the case of focusing (internal focusing), a moving method of the lenses is not limited to this. For example, any of the lenses L 1  and L 3  to L 6  other than the second group lens L 2  may move in the direction of the optical axis AX in the case of focusing. Here, a system which performs the focusing by the movement of the first group lens L 1  is called a front lens feeding system. Moreover, all of the first group lens L 1  to the sixth group lens L 6  or a plurality of lenses among these may be moved in the case of focusing. Here, a system which moves all of the lenses is called an all group feeding system. 
     Moreover, although in the above-mentioned embodiment, the description is given of the case where the guide pipes  36 A and  36 B and the fixed cylinder  10  are separately constituted and the guide pipes  36 A and  36 B are supported by the fixed cylinder  10 , the constitution of the guide pipes  36 A and  36 B and the fixed cylinder  10  is not limited to this. For example, the guide pipes  36 A and  36 B and the fixed cylinder  10  may be integrally formed. 
     Moreover, although in the above-mentioned embodiment, the description is given of the case where the fourth group lens L 4  and the sixth group lens L 6  are held by the common lens sliding cylinder  14 , a holding form of the lenses is not limited to this. The fourth group lens L 4  and the sixth group lens L 6  may be held by separate lens sliding cylinders. 
     The number of lenses and the lens arrangement according to the above-mentioned embodiment are one example. That is, the lens barrel should include at least a lens that is held by a lens sliding cylinder fixed to the guide bar  30 A, and a lens that is held by another lens sliding cylinder fixed to the guide bar  30 B. 
     Moreover, although in the above-mentioned embodiment, the description is given of the case where the lens is adopted as an optical member, the optical member is not limited to this. An optical member, such as a mirror and an image capturing element, can be adopted. 
     The above-mentioned embodiment is a preferable embodiment of the present invention. However, the present invention is not limited to the above-mentioned embodiment, and other embodiments, variations and modifications may be made without departing from the scope of the present invention.