Abstract:
A lens barrel device includes a lens mounted in a lens frame that is threaded into an annular adjusting ring. The adjusting ring is coupled using a bayonet to a lens barrel. The lens barrel includes first and second flanges on the inner periphery of the lens barrel that define grooves for receiving bayonet projections on the annular adjusting ring. The bayonet coupling structure of the annular adjusting ring includes semispherical projections for elastically engaging inner walls of the grooves and also includes a rotation regulating stopper for engaging an end wall of an opening in one of the inner flanges so as to regulate rotation of the annular adjusting ring, and hence the lens, relative to the lens barrel. The end wall includes a groove for receiving a jig that can release the bayonet coupling structure of the annular adjusting ring from the lens barrel.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Conventionally, in lens barrels that include a lens supporting structure for holding the lens and moving the lens along the optical axis of the lens barrel, a lens frame holds the lens and is screwed into an adjusting ring that is mounted on the lens barrel, and a bayonet-type structure is used as the mounting structure of the adjusting ring to the lens barrel. For example, three projections formed at equal spacings around the outer periphery of the adjusting ring are aligned with three notches of three grooves formed around the inner periphery of the lens barrel. The three projections are passed through the notches, and the adjusting ring is rotated so the projections rotate in the grooves so that the projections are no longer aligned with the notches. Moreover, leaf springs are provided between the projections and the grooves so that the rotation of the adjusting ring presses the projections against the leaf springs that bend to exert a holding force between the adjusting ring and the lens barrel.  
           [0002]    In such a conventional arrangement, adjustment along the optical axis is first achieved by rotating the lens frame in a screw connection with the annular adjusting ring that moves the lens frame back and forth along the optical axis to vary the spacing of the lens mounted in the lens frame and other lenses. Next, the lens is moved in a plane perpendicular to the optical axis by changing the fitting positions of the bayonet-type projections and grooves, for example, by rotating the adjusting ring by 120 degrees to align different projections and notches until the connection that optimizes the centering of the lens on the optical axis is achieved. When the optimum alignment is found, an adhesive is coated in the bayonet grooves at the optimum position to bond the adjusting ring to the lens barrel, thus completing the optical axis adjustment operation of the lens and the lens barrel.  
           [0003]    According to the above method, it is necessary to rotate the lens around the optical axis in order to find the optimum position. When the lens frame is rotated relative to the annular adjusting ring in order to obtain the proper position of the lens along the optical axis, the force is transmitted to the annular adjusting ring and may cause it to rotate relative to the lens barrel. In this case, there has been the drawback that the leaf springs revolve together with the annular adjusting ring due to the frictional resistance with the annular adjusting ring. If the direction of rotation of the annular adjusting ring is in the same direction as the direction of releasing the annular adjusting ring from the lens barrel, the tight connection between the annular adjusting ring and the lens barrel intended to be provided by the leaf springs is loosened. This increases the time required to make the proper optical axis adjustments.  
           [0004]    Moreover, the leaf springs are provided for the original optical axis adjustment, but they are not needed after the adjustment is fixed by adhesive. However, the leaf springs cannot be removed and thus they remain in the lens barrel even though they no longer serve a useful purpose.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    The present invention relates to a lens barrel device that enables adjustment of a lens along the optical axis of the lens barrel device without requiring the use of leaf springs. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    The present invention will become more fully understood from the detailed description given below and the accompanying drawings, which are given by way of illustration only and thus are not limitative of the present invention, wherein:  
         [0007]    [0007]FIG. 1 is a front perspective view that shows an electronic still camera with an embodiment of the lens barrel device of the present invention;  
         [0008]    [0008]FIG. 2 is an exploded perspective view of the lens barrel device of FIG. 1;  
         [0009]    [0009]FIG. 3 is a cross-sectional side view along the optical axis of the lens barrel device of FIG. 1 at the retracted position;  
         [0010]    [0010]FIG. 4 is a cross-sectional side view along the optical axis of the lens barrel device of FIG. 1 at the telephoto position;  
         [0011]    [0011]FIG. 5 is a cross-sectional side view along the optical axis of the lens barrel device of FIG. 1 at the wide-angle position;  
         [0012]    [0012]FIG. 6A is an enlarged exploded perspective view of the fixed barrel and rotatable barrel of the lens barrel device of FIG. 1;  
         [0013]    [0013]FIG. 6B is an enlarged cross-sectional view of a portion of the fixed lens barrel of FIG. 6A;  
         [0014]    [0014]FIG. 7 is an enlarged exploded perspective view of the first lens, the lens frame, the annular adjusting ring, and the first lens barrel of the lens barrel device of FIG. 1;  
         [0015]    [0015]FIG. 8 is an enlarged cross-sectional view of the assembled first lens, lens frame, adjusting ring, and first lens barrel of the lens barrel device of FIG. 1;  
         [0016]    [0016]FIG. 9 is a further enlarged cross-sectional view of a portion of FIG. 8;  
         [0017]    [0017]FIG. 10A is an enlarged exploded perspective view of a rotation regulating stopper and a mating portion of the first lens barrel of the lens barrel device of FIG. 1; and  
         [0018]    [0018]FIG. 10B is a further enlarged perspective view of a portion of the first lens barrel shown in FIG. 10A. 
     
    
     DETAILED DESCRIPTION  
       [0019]    An embodiment of the lens barrel device of the present invention and its method of assembly that is also part of the present invention will be described with reference to the drawings. In the following description, elements that are essentially identical, except for their location, may be denoted by the same reference symbol that may be recited only once when the essentially identical elements are being referenced.  
         [0020]    [0020]FIG. 1 is a front perspective view that shows an electronic still camera with an embodiment of the lens barrel device of the present invention. As shown in FIG. 1, the electronic still camera  1  has a generally rectangular shaped body that carries a lens barrel device  2 , a finder window  3 , a strobe light adjusting sensor  4 , and a self-timer  5  on the front, and a pop-up strobe  6  and a release switch  7  on the top. A finder ocular, a liquid crystal panel, and an operation panel, which are not shown, may conventionally be on the back of the camera. The electronic still camera  1  is of the retractable lens type, and, as shown in FIG. 1, the lens barrel device protrudes from the front with the lens barrel device extended from the camera body for use.  
         [0021]    [0021]FIG. 2 is an exploded perspective view of the lens barrel device of FIG. 1. FIGS.  3  to  5  are cross-sectional side views along the optical axis of the lens barrel device  2  of FIG. 1. FIG. 3 shows the lens barrel device  2  at the retracted position, and FIGS. 4 and 5 show the lens barrel device  2  at the telephoto and wide-angle positions, respectively.  
         [0022]    As shown in FIGS.  2  to  5 , the lens barrel device  2  includes a first lens  11 , a second lens  12 , a first lens barrel  13 , a second lens barrel  14 , a movable barrel  15 , a fixed barrel  16 , and a rotatable barrel  17 . The first lens  11  includes an optical axis that preferably coincides with optical axis  20  defined in terms of precise alignment with a CCD imaging element (not shown in the drawings).  
         [0023]    [0023]FIG. 6A is an enlarged exploded perspective view of the fixed barrel  16  and the rotatable barrel  17  of the lens barrel device of FIG. 1. FIG. 6B is an enlarged cross-sectional view of a portion of the fixed barrel  16  of FIG. 6A. As shown in FIG. 6A, the rotatable barrel  17  is supported with free rotation by the fixed barrel  16  aligned generally along the optical axis  20  in positions determined by the engagement of projections  42 ,  44 ,  46  formed on the inner periphery of the rotatable barrel  17  with grooves  40  formed around the outer periphery of the fixed barrel  16 . The grooves  40  of the fixed barrel  16  are formed between a flange  48  and a projecting strip  50  formed at one end of the fixed barrel  16 . Three notches  52 ,  54 ,  56  are formed in the projecting strip  50 , and the three projections  42 ,  44 ,  46  are engaged with the grooves  40  via the notches  52 ,  54 ,  56 .  
         [0024]    As shown in FIG. 2, a gear  18  is formed on the outer periphery of the rotatable barrel  17 . The drive of a zoom motor  19  is transmitted to the gear  18  in order to rotate the rotatable barrel  17  while it is in contact with the outer periphery of the fixed barrel  16 . The state of the lens barrel device  2  of FIG. 2 is changed from the retracted barrel position shown in FIG. 3 to the telephoto position shown in FIG. 4 by rotating the rotatable barrel  17  to achieve the lens positions shown in FIG. 4. Further rotation of the rotatable barrel  17  from the telephoto position to the wide-angle position produces the wide-angle positions of the lenses shown in FIG. 5.  
         [0025]    Second lens cam grooves  21  for moving the second lens barrel  14  in the direction of the optical axis  20  and guide grooves  22  for guiding the movable lens barrel  15  in the direction of the optical axis  20  without rotation relative to the rotatable barrel  17  are formed at the inner periphery of the rotatable barrel  17 . These second lens cam grooves  21  and guide grooves  22  are formed at three equally spaced positions around the optical axis  20 .  
         [0026]    Second lens guide grooves  23  for guiding the second lens barrel  14  in the direction of the optical axis  20  without rotation and movable barrel cam grooves  24  for moving the movable barrel  15  in the direction of the optical axis  20  are formed on the inner periphery of the fixed barrel  16 . The second lens guide grooves  23  and the movable barrel cam grooves  24  are formed at three equally spaced positions around the optical axis  20 .  
         [0027]    Movable barrel cam pins  25  are provided on the outer periphery of the movable barrel  15 . These movable barrel cam pins  25  are provided at three equally spaced positions around the optical axis  20  and engage with the movable barrel cam grooves  24  formed on the fixed barrel  16  and the movable barrel guide grooves  22  formed on the rotatable barrel  17 . If the rotatable barrel  17  is rotated, the movable barrel  15  is moved in the direction of the optical axis  20  while rotating around the fixed barrel  16  by the action of the movable barrel cam grooves  24  and the movable barrel guide grooves  22 .  
         [0028]    First lens cam grooves  26  for moving the first lens barrel  13  in the direction of the optical axis  20  are formed on the inner periphery of the movable barrel  15 . The first lens cam grooves  26  are provided at three positions equally spaced around the optical axis  20 . Guide grooves  27  are formed on the inner periphery of the first lens barrel  13  so that they are parallel to the optical axis and engage with guide projections  30  formed on the second lens barrel  14 . First lens cam pins  28  are provided on the outer periphery of the first lens barrel  13  at positions around the optical axis  20  so that they engage with the first lens cam grooves  26  formed on the inner periphery of the movable barrel  15 . When the movable barrel  15  is rotated, the first lens barrel  13  is moved relative to the second lens barrel  14  generally along the optical axis  20  by interaction of the first lens cam grooves  26  and the guidance of the guide projections  30  of the second lens barrel  14 .  
         [0029]    Second lens cam pins  29  are provided on the outer periphery of the second lens barrel  14  at positions around the optical axis  20  so that they with engage the second lens cam grooves  21  of the rotatable barrel  17  and the second lens guide grooves  23  of the fixed barrel  16 . When the rotatable barrel  17  is rotated, the second lens barrel  14  is moved generally along the optical axis  20  relative to the fixed barrel  16  by the action of the second lens cam grooves  21  of the rotatable barrel  17  and the second lens guide grooves  23  of the fixed barrel  16 . Additionally, a pair of springs  37 ,  37  connect the second lens barrel  14  to the fixed barrel  16 . The springs  37 ,  37  are provided at certain positions around the optical axis  20  so that the second lens barrel  14  is biased toward the image plane side.  
         [0030]    Furthermore, a pair of arms  38 ,  38  are integrally formed on one side of the optical axis on the outer part of the front end, that is, the object side, of the second lens barrel  14 . The arms  38 ,  38  extend from the front end of the second lens barrel  14  parallel to the optical axis  20  in their lengthwise direction, and each arm  38  includes a guide projection  30  that includes a guide member integrally formed at the outer periphery of the front end of each arm  38 . The guide projections  30  engage with the guide grooves  27  formed on the inner periphery of the first lens barrel  13 . The first lens barrel  13  is guided back and forth along the optical axis  20  by the second lens barrel  14 .  
         [0031]    As shown in FIGS.  3 - 5 , the first lens  11  is mounted in the first lens barrel  13  with its optical axis closely matched to the optical axis  20  that extends to a CCD (not shown in the drawings). FIG. 7 is an enlarged exploded perspective view of the first lens and lens frame, the annular adjusting ring, and the first lens barrel of the lens barrel device of FIG. 1.  
         [0032]    As shown in FIG. 7, the first lens  11  is mounted in a lens frame  60  that is mountable in the annular adjusting ring  62  that, in turn, is mountable in the first lens barrel  13 . FIG. 8 is an enlarged cross-sectional view of the assembled lens  11 , lens frame  60 , annular adjusting ring  62 , and first lens barrel  13 . FIG. 9 is a further enlarged cross-sectional view of a portion of FIG. 8. The lens frame  60  is connected to the inner periphery of the annular adjusting ring  62  via mating screw threads  63  on the lens frame  60  with screw threads on the annular adjusting ring  62 . Because FIGS.  3 - 5  merely show a general view of the mechanical connections of the lens barrel device, the first lens barrel  13  appears to be a one piece structure holding the lens  11  because an illustration of the lens frame  60  and annular adjusting ring  62  (as well as the detailed shape of the first lens  11 ) has been omitted for simplicity of illustration.  
         [0033]    As shown in FIG. 7, the first lens barrel  13  and the annular adjusting ring  62  are connected by a first coupling structure on the inner periphery on the first lens barrel  13  and a second coupling structure on the other periphery of the annular adjusting ring  62 . The coupling structures include three bayonet projections  66  formed on the outer periphery of the annular adjusting ring that are fitted into three bayonet grooves  64  formed in an inner peripheral flange  61  of the first lens barrel  13 . The three notches  65  are also formed in the inner peripheral flange  61  on the front of the first lens barrel  13 , and the three bayonet projections  66  are fitted into the three bayonet grooves  64  via the three notches  65 . As shown in FIG. 7A, an inner flange  72  extends on the inner periphery of the first lens barrel  13  and forms an inner side of each bayonet groove  64 .  
         [0034]    Additionally, semispherical elastic engagement components  68  are formed as protrusions on first portions of the bayonet projections  66 . As shown in FIGS. 8 and 9, when the bayonet projections  66  are fitted into the bayonet grooves  64 , the elastic engagement components  68  engage with an inner wall surface  64 A of the bayonet grooves  64  with elastic or plastic deformation.  
         [0035]    Furthermore, as shown in FIG. 7, a rotation regulating stopper  70 , which is a regulating member, is integrally formed on a second portion of one bayonet projection  66  of the three bayonet projections  66 . Fig. 10A is an enlarged exploded view of the rotation regulating stopper  70  and a mating portion of the first lens barrel  13 . FIG. 10B is a further enlarged perspective view of a portion of the first lens barrel  13  shown in FIG. 10A. When the bayonet projection of the annular adjusting ring  62  is inserted into one of the three notches  65  and rotated into the bayonet groove  64  of the first lens barrel  13 , the rotation regulating stopper  70  engages an opening partially defined by the end surface  73  formed on the inner flange  72 . This regulates the rotation of the annular adjusting ring  62  within the first lens barrel  13 .  
         [0036]    As shown in Figs.  10 A- 10 B, a jig insertion groove  74  is formed in the end surface  73  of the inner flange  72 . The engagement of the rotation regulating stopper  70  with the end surface  73  can be released with a jig by inserting the jig into the jig insertion groove  74 .  
         [0037]    Additionally, as shown in FIG. 8, an annular decorative sheet  76  is mounted to the front of the first lens barrel  13 . As shown in FIG. 9, the decorative sheet  76  is bonded to the inner peripheral flange  61  of the first lens barrel  13  and a left side circular end face  67  of the annular adjusting ring  62  is extended so as to be coplanar with the front end of the inner peripheral flange  61 .  
         [0038]    Next, the optical axis adjusting operation of the first lens  11  for the first lens barrel  13  constructed as described above will be explained. First, the lens frame  60  that holds the first lens  11  is screwed onto the annular adjusting ring  62 . Next, the annular adjusting ring  62  is mounted in the first lens barrel  13 . At this time, the three bayonet projections  66  are fitted into the three bayonet grooves  64  that are selected arbitrarily. Thereby, the first lens  11  is mounted in the first lens barrel  13 .  
         [0039]    Then, with regard to the optical axis adjusting operation, first, the lens frame  60  is rotated within the annular adjusting ring  62  via screw threads  63  so that the lens frame  60  is moved forward and backward within the annular adjusting ring  62  in the direction of the optical axis  20 , which adjusts the positioning of the lens  11  along the optical axis  20 . At this time, the annular adjusting ring  62  does not rotate with the lens frame  60  because the rotation regulating stopper  70  is engaged with the opening partially defined by end surface  73  formed on the inner flange  72  so as to prevent rotation of the annular adjusting ring  62 .  
         [0040]    Next, whether the optical axis of the first lens  11  and the optical axis  20  of the CCD (not shown) match in this state is confirmed. If they do not match, the engagement of the rotation regulating stopper  70  with the opening partially defined by end surface  73  formed on the inner flange  72  is released by a jig. Then the annular adjusting ring  62  is rotated so as to release the bayonet fitting, and the annular adjusting ring  62  is removed from the first lens barrel  13 .  
         [0041]    Then, the annular adjusting ring is rotated 120 degrees about the optical axis in order to align the bayonet projections  66  with different bayonet grooves  64  and the annular adjusting ring  62  is again mounted in the first lens barrel  13 . This remounting results in a slight displacement of the first lens  11  in a plane perpendicular to the optical axis so that the optical axis of the first lens  11  and the optical axis  20  of the CCD match.  
         [0042]    Thus, the lens barrel device  2  enables adjustment and alignment of the optical axis of the first lens  11  with the optical axis  20  of the CCD without requiring leaf springs, as taught in the prior art. Rather, the elastic engagement component  68  elastically engages with the first lens barrel  13  and the rotation regulating stopper  70 . Th elastic engagement component  68  and the rotation regulating stopper  70  are integrally formed with the annular adjusting ring  62 .  
         [0043]    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. Rather, the scope of the invention shall be defined as set forth in the following claims and their legal equivalents. 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.