Abstract:
As a cylindrical optical connector, an optical connector includes a pushing member that has a structure that is suitable for holding a coil spring in the optical connector, and that has a structure that, even if clockwise or counterclockwise twisting occurs with respect to an axial direction of the optical connector, properly restricts rotation of the pushing member and, thus, does not allow disengagement of the pushing member caused by an applied force resulting from the rotation of the pushing member to easily occur.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an optical connector. More specifically, the present invention relates to a structure of a component for mounting an elastic member, such as a coil spring, in the optical connector to, when optical connectors are connected to each other, maintain a state in which a ferrule of one of the connectors and a ferrule of the other optical connector are physically pushed against each other, and keep optical fibers optically coupled to each other, the elastic member applying a force that at least causes the ferrule of one of the optical connectors to push the ferrule of the other optical connector at all times. 
         [0003]    2. Description of the Related Art 
         [0004]    An existing optical connector of a type that optically couples optical fibers to each other by inserting a guide pin protruding from an end surface of a ferrule of the optical connector into a guide hole in an end surface of a ferrule of a mating optical connector, by positioning the ferrules with respect to each other, and by physically pushing the ferrule end surfaces against each other is available. In order to keep the ferrule end surfaces pushed against each other at all times, such an optical connector includes an elastic member, such as a coil spring, therein. The elastic member, such as a coil spring, is formed so as to push out the ferrule in a front end direction. By an elastic force (an urging force), the elastic member, such as a coil spring, allows the ferrule end surface to be pushed against the ferrule end surface of the mating optical connector at all times. 
         [0005]    For example, a rectangular optical connector described in Japanese Patent No. 5518979 has a structure in which movement towards a back end side of a spring (coil spring) that urges a ferrule from a back end side to a front end side is restricted by a pushing member (spring pusher) to push out the ferrule in a front end direction. The spring pusher is a rectangular pushing member including bent sections that are vertically bent at two respective sides. By engaging retaining lugs protruding from outer surfaces of the bent sections at the two respective sides with engaging sections in inner surfaces at two respective sides of the housing (receptacle housing) of the optical connector, the spring pusher is fixed to the housing of the optical connector. 
         [0006]    As in the related art described above, if an optical connector is a rectangular optical connector, the retaining lugs on the outer surfaces of the bent sections of the rectangular pushing member, such as the above-described spring pusher, at the two respective sides can firmly engage with the engaging sections in the inner surfaces at the two respective sides of the housing of the optical connector. However, if an engaging structure including retaining lugs and engaging sections such as that of the related art is applied to a cylindrical optical connector, the retaining lugs and the engaging sections need to be formed in accordance with the curved surface of the housing of the cylindrical optical connector, as a result of which it is troublesome to produce the optical connector compared to the optical connector of the related art. Therefore, this engaging structure is not a structure that is suitable for the cylindrical optical connector. 
         [0007]    In addition, if the housing of the cylindrical optical connector to which an engaging structure such as that of the related art is applied is twisted clockwise or counterclockwise with respect to an axial direction, rotation generated by the twisting of the housing is restricted only by the engaging structure including the retaining lugs and the engaging sections. This causes a force that is generated by the rotation to concentrate in the engaging structure, as a result of which the pushing member and the housing of the optical connector are disengaged from each other. This may cause the optical connector to become disassembled. 
       SUMMARY OF THE INVENTION 
       [0008]    Accordingly, it is an object of the present invention to provide, as a cylindrical optical connector, an optical connector including a pushing member that has a structure that is suitable for holding a coil spring in the optical connector, and that has a structure that, even if clockwise or counterclockwise twisting occurs with respect to an axial direction of the optical connector, properly restricts rotation of the pushing member and, thus, does not allow disengagement of the pushing member caused by an applied force resulting from the rotation of the pushing member to easily occur. 
         [0009]    According to an embodiment of the present invention, there is provided an optical connector including a ferrule that is connected to an optical fiber cable; a fitting section that holds a front end portion of the ferrule therein and that is fitted to a mating optical connector; an elastic member that is disposed at a back end portion of the ferrule; an accommodation section that accommodates the ferrule and the elastic member therein; and a pushing member that pushes the elastic member into the accommodation section and that is mounted in the accommodation section. In the optical connector, the accommodation section includes a retaining section that protrudes from an inner wall of the accommodation section. In addition, the pushing member includes a lock section for receiving the retaining section. Further, when the pushing member is mounted in the accommodation section, the lock section is fixed by being pushed against the retaining section by an elastic force of the elastic member accommodated in the accommodation section. 
         [0010]    According to a preferred embodiment of the present invention, in the optical connector, the pushing member may include a cutaway section that is formed by cutting out a portion of a side wall of the pushing member, and the cutaway section may be formed such that, when mounting the pushing member in the accommodation section, the retaining section and the cutaway section are aligned and the pushing member is pushed into the accommodation section to pass the retaining section through the cutaway section. 
         [0011]    According to another preferred embodiment of the present invention, in the optical connector, the pushing member may include a lock protrusion that protrudes from an edge of the lock section facing the cutaway section; the lock protrusion may be formed so as to, when mounting the pushing member in the accommodation section, traverse the retaining section as a result of the retaining section passing through the cutaway section and the pushing member rotating from a state in which the pushing member contacts a surface in the accommodation section; and, after the pushing member is mounted in the accommodation section, the lock protrusion may come into contact with the retaining section to restrict rotation of the pushing member. 
         [0012]    According to still another preferred embodiment of the present invention, in the optical connector, the pushing member may include a concave-shaped jig receiver that, when mounting the pushing member in an end portion of the accommodation section, receives a jig for rotating the pushing member. 
         [0013]    According to still another preferred embodiment of the present invention, in the optical connector, the pushing member may include a recessed section in a surface of the pushing member that contacts the elastic member, and the recessed section may hold an end portion of the elastic member and restrict displacement of the elastic member. 
         [0014]    Unlike the above-described related art, the optical connector according to the present invention includes an engaging structure that is suitable for a cylindrical shape. Accordingly, even if clockwise or counterclockwise twisting occurs with respect to the axial direction of the optical connector, the retaining section that is formed on the inner wall of the accommodation section of the optical connector and the lock protrusion of the pushing member can restrict the rotation of the pushing member of the optical connector generated by the twisting, and, thus, prevent the pushing member from being removed from the accommodation section of the optical connector. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is an external view of an optical connector according to an embodiment of the present invention and a mating optical connector; 
           [0016]      FIG. 2  is an external view of the optical connector according to the embodiment of the present invention; 
           [0017]      FIG. 3  shows a structure of components of the optical connector according to the embodiment of the present invention; 
           [0018]      FIG. 4  is a sectional view of the optical connector according to the embodiment of the present invention; 
           [0019]      FIGS. 5A to 5C  are external views of a pushing member that is mounted in an end portion of an accommodation section of the optical connector according to the embodiment of the present invention; 
           [0020]      FIGS. 6A and 6B  are an external view and a sectional view, respectively, of a state prior to pushing the pushing member into the accommodation section of the optical connector according to the embodiment of the present invention; 
           [0021]      FIGS. 7A and 7B  are an external view and a sectional view, respectively, of a state in which the pushing member has been pushed into the accommodation section of the optical connector according to the embodiment of the present invention; 
           [0022]      FIGS. 8A and 8B  are an external view and a sectional view, respectively, of a state in which the pushing member has been rotated rightward from the state in which the pushing member has been pushed into the accommodation section of the optical connector according to the embodiment of the present invention; and 
           [0023]      FIGS. 9A and 9B  are an external view and a sectional view, respectively, of a state in which the pushing member has been mounted in the end portion of the accommodation section of the optical connector according to the embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    An embodiment of the present invention is hereunder described with reference to the drawings. In all of the figures for illustrating the embodiment, as a general rule, corresponding members are given the same reference numerals, and the same descriptions thereof are not repeated. 
         [0025]      FIG. 1  is an external view of an optical connector according to the embodiment of the present invention and a mating optical connector. A cylindrical optical connector  100  corresponds to the optical connector according to the embodiment of the present invention. The optical connector  100  includes at its front end portion a cylindrical fitting section  102  for connecting a mating optical connector  150  thereto. The optical connector  100  includes at its back end portion a cylindrical accommodation section  104  for accommodating a pushing member  200 , a coil spring  202 , and a ferrule  204  coupled to an optical cable  106  (see  FIG. 3 ), which are described below. 
         [0026]    The cylindrical mating optical connector  150  includes at its front end portion a fitting section  152  that is fitted to the fitting section  102  of the optical connector  100  to optically couple an optical cable  156  and the optical cable  106  to each other. At a side that is situated closer to a back end than the fitting section  152  is, the mating optical connector  150  includes a cord tube  154  that accommodates the optical cable  156  therein. The optical cable  156  extends from a back end portion of the cord tube  154 . 
         [0027]      FIG. 2  is an external view of the optical connector according to the embodiment of the present invention. As described above, the optical connector  100  includes the fitting section  102  at its front end portion, and the accommodation section  104  at its back end portion. The optical cable  106  extends from a back end portion of the accommodation section  104 . A flange section  108  for mounting the optical connector  100  on a housing of, for example, a device is provided between the fitting section  102  and the accommodation section  104 . Water-proof packing  110  for preventing entry of water from a gap between the housing and the flange section  108  when the optical connector  100  is mounted on the housing of, for example, the device is provided on a surface of the flange section  108  that contacts the housing (a surface at a side of a back end of the optical connector  100 ). The fitting section  102 , the accommodation section  104 , and the flange section  108  are integrated with each other by die casting. A lock protrusion  112  for fixing the fitting and connection with the fitting section  152  of the mating optical connector  150  is provided on an outer wall of the fitting section  102 . The columnar or disc-shaped pushing member  200  is mounted in an end portion of the accommodation section  104  of the optical connector  100 . 
         [0028]      FIG. 3  illustrates a structure of components of the optical connector according to the embodiment of the present invention. An inner side of the end portion of the accommodation section  104  of the optical connector  100  corresponds to a mounting section  114  for accommodating and mounting the pushing member  200 . The mounting section  114  includes retaining sections  116  that protrude vertically from an inner wall of the end portion of the accommodation section  104 . In the embodiment shown in  FIG. 3 , two retaining sections  116  are provided. The two retaining sections  116  are provided at opposite locations on the cylindrical mounting section  114 . That is, in the cylindrical mounting section  114 , one of the retaining sections  116  is provided at a location that faces and that is 180 degrees apart from the other retaining section  116 . The number of retaining sections  116  is not limited to two. The accommodation section  104  accommodates, in addition to the pushing member  200 , the coil spring  202  and the ferrule  204  coupled to the optical cable  106 . In another embodiment, instead of the coil spring  202 , other elastic members may be used as long as the elastic members are capable of pushing the ferrule  204  in a front end direction. 
         [0029]    The ferrule  204  includes at its front end portion a pair of guide pins  206  for preventing shifts in the connection of the ferrule  204  with the mating optical connector. An adhesive  208  for fixing core wires of an optical fiber is applied to a surface of an upper portion of the ferrule  204 . When the coil spring  202  and the ferrule  204  to which the optical cable  106  is coupled are accommodated in the accommodation section  104  of the optical connector  100 , and the pushing member  200  is mounted in the end portion (the mounting section  114 ) of the accommodation section  104  against an elastic force of the coil spring  202 , the coil spring  202  is compressed by being pushed into a location between the ferrule  204  and the pushing member  200 , so that the ferrule  204  is urged at all times in the front end direction of the connector  100  (that is, in the direction of the mating optical connector) (refer to  FIG. 4 ). 
         [0030]      FIG. 4  is a sectional view of the optical connector according to the embodiment of the present invention, and shows a state in which the ferrule  204  is urged at all times in the front end direction of the optical connector  100  by urging the coil spring  202  by the pushing member  200 . An accommodation space  118  for accommodating the ferrule  204 , the coil spring  202 , and the optical cable  106  is formed in the accommodation section  104 . The ferrule  204  is formed so as to be slidable in the accommodation space  118  in the front end direction or the back end direction. As shown in cross section in  FIG. 4 , the accommodation space  118  is narrow towards a front end side and is wide towards a back end side. That is, an inner wall of the accommodation section  104  is formed obliquely in such a manner as to become gradually narrower in the front end direction from a portion where a restricting surface  120  is provided. 
         [0031]    The ferrule  204  is urged in the front end direction of the optical connector  100  by the coil spring  202 , and comes into contact with an inner wall of a front end portion of the accommodation space  118 , so that movement of the ferrule  204  in the front end direction is restricted. When connecting the optical connector  100  to the mating optical connector  150 , a ferrule (not shown) in the mating optical connector  150  pushes in the ferrule  204  in the back end direction. However, since the ferrule  204  is subjected to an elastic force of the coil spring  202  at all times, a force that pushes in the ferrule  204  in the front end direction acts upon the ferrule  204 . The coil spring  202  not only acts to push in the ferrule  204  in the front end direction of the optical connector  100  but also acts to push out the pushing member  200  in the back end direction. 
         [0032]    The restricting surface  120  is provided at a boundary between the mounting section  114  and the accommodation space  118 , and can restrict movement of the pushing member  200  in the front end direction when pushing the pushing member  200  into and mounting the pushing member  200  in the mounting section  114 . 
         [0033]      FIGS. 5A to 5C  are external views of the pushing member that is mounted in the end portion of the accommodation section of the optical connector according to the embodiment of the present invention.  FIG. 5A  is a front view of a front surface of the pushing member  200  (a surface at a side of the back end portion of the optical connector  100 ). Lock protrusions  212 , jig receivers  214 , a cable holding section  216 , cutaway sections  218 , and lock sections  220  are provided at the front surface of the pushing member  200 . The lock protrusions  212  are formed such that, when the pushing member  200  is mounted in the mounting section  114  of the optical connector  100 , the lock protrusions  212  are caught by the retaining sections  116  that are formed on the inner wall of the end portion of the accommodation section  104 . The lock protrusions  212  are formed on front surfaces of the respective lock sections  220  formed by reducing the thickness of an edge of the columnar or disk-shaped pushing member  200 , and are positioned at ends of the respective lock sections  220  facing the cutaway sections  218  that are formed by cutting out recessed portions from the pushing member  200 . 
         [0034]    The jig receivers  214  are portions that are located at the edge of the columnar or disk-shaped pushing member  200 , and that are formed with concave shapes by cutting the front surface of the pushing member  200  (the surface at the side of the back end of the optical connector  100 ) and reducing the thickness of the edge. The jig receivers  214  can receive a front end of a jig that is used when accommodating and mounting the pushing member  200  in the end portion (the mounting section  114 ) of the accommodation section  104  of the optical connector  100 . By inserting the front end of the jig into the jig receivers  214 , the jig can push the pushing member  200  into the accommodation section  104  of the optical connector  100  and rotate the pushing member  200 . 
         [0035]    The cable holding section  216  is formed by forming a cut from the edge to the center of the pushing member  200 . The width of the cut is approximately equal to a width that allows the optical cable  106  to be held. When mounting the pushing member  200  in the end portion of the accommodation section  104  of the optical connector, the optical cable  106  coupled to the ferrule  204  accommodated in the accommodation section  104  is brought out of the optical connector  100  from the cable holding section  216 . 
         [0036]    The cutaway sections  218  are formed by cutting out portions of a side wall of the columnar or disk-shaped pushing member  200 . The shape of the cutaway sections  218  allows the retaining sections  116  that protrude from the inner wall of the accommodation section  104  to pass therethrough. Therefore, when mounting the pushing member  200  in the end portion of the accommodation section  104  of the optical connector  100 , the retaining sections  116  and the cutaway sections  218  are aligned and the pushing member  200  is pushed into the end portion of the accommodation section  104  to pass the retaining sections  116  through the cutaway sections  218 . 
         [0037]    The lock sections  220  are portions that are formed by cutting the edge of the columnar or disk-shaped pushing member  200  from the front surface of the pushing member  200  and reducing the thickness of the edge of the pushing member  200 . When the pushing member  200  is mounted in the end portion of the accommodation section  104  of the optical connector  100 , the lock sections  220  are fixed by being pushed against back surfaces of the retaining sections  116  (surfaces towards a front end of the optical connector) by an elastic force of the coil spring  202  accommodated in the accommodation section  104 . That is, when the pushing member  200  is mounted in the mounting section  114  in the accommodation section  104 , it is possible to restrict rotation of the pushing member  200 , which is caused by twisting, by inserting the retaining sections  116  into the lock sections  220  and bringing the lock protrusions  212  on the lock sections  220  into contact with side walls of the retaining sections  116 . 
         [0038]      FIG. 5B  is an external perspective view of the front surface of the pushing member  200 . Referring to  FIG. 5B , it can be confirmed that the lock protrusions  212  protrude from ends of the respective lock sections  220 . In one example of the pushing member  200  shown in  FIGS. 5A to 5C , each lock section  220  is formed by cutting the front surface of the pushing member  200  and reducing the thickness thereof to approximately one half of the original thickness. 
         [0039]      FIG. 5C  is an external perspective view of a back surface of the pushing member  200 . The back surface of the pushing member  200  (the surface of the pushing member  200  that contacts the coil spring  202 ) includes a recessed section  222  and a recessed-section side wall  224 . The recessed section  222  is formed by cutting a cylindrical shape from a central portion of the pushing member  200  to have a certain depth. By passing the optical cable  106  inwardly of an inner side of the recessed section  222 , the recessed section  222  can hold an end portion of the coil spring  202  that is disposed at a back end of the ferrule  204 . If, for example, the coil spring  202  is compressed, the recessed section  222  can restrict displacement of the end portion of the coil spring  202 . More specifically, the recessed-section side wall  224 , which is a side wall of the recessed section  222 , can prevent displacement and movement of the coil spring  202  from the center of the pushing member  200 . 
         [0040]      FIGS. 6A to 9B  are external views and sectional views showing states of respective stages when pushing the pushing member into and mounting the pushing member in the accommodation section of the optical connector according to the embodiment of the present invention.  FIGS. 6A and 6B  show a state prior to pushing the pushing member  200  into the end portion (the mounting section  114 ) of the accommodation section  104  of the optical connector  100 . Referring to  FIG. 6A , the pushing member  200  is held such that the optical cable  106  is passed through the cable holding section  216 , the front end of a jig (not shown) is inserted into the jig receivers  214 , and the retaining sections  116  and the cutaway sections  218  are aligned. 
         [0041]      FIG. 6B  shows a state of the inside of the accommodation section  104 , where the ferrule  204  coupled to the optical cable  106  and the coil spring  202  are accommodated in the accommodation section  104 . At this time, a force is not applied to the coil spring  202 , and an elastic force does not act. 
         [0042]      FIG. 7A  shows a state in which the pushing member  200  has been pushed to an inner side of the accommodation section  104 . By pushing the pushing member  200  into the accommodation section  104 , the cutaway sections  218  are aligned with the retaining sections  116  and receive the retaining sections  116  located at the front side, and the retaining sections  116  pass through the cutaway sections  218  and are positioned from a back-surface side to a front-surface side of the pushing member  200 . 
         [0043]      FIG. 7B  shows a state of the inside of the pushed-in pushing member  200 . When the pushing member  200  is pushed into the accommodation section  104 , the back surface of the pushing member  200  comes into contact with the restricting surface  120  that is disposed at the boundary between the accommodation space  118  and the mounting section  114  in the accommodation section  104 , so that further pushing of the pushing member  200  into the inner side of the accommodation section  104  is restricted. When the pushing member  200  is pushed into the accommodation section  104  until the pushing member  200  comes into contact with the restricting surface  120 , the lock protrusions  212  on the front surface of the pushing member  200  can move around to back sides of the retaining sections  116 . By pushing the pushing member  200  into the accommodation section  104 , the coil spring  202  is brought into a compressed state. 
         [0044]      FIGS. 8A and 8B  show a state in which the pushing member has been rotated rightwards by a predetermined angle (such as 45 degrees) from the state shown in  FIGS. 7A and 7B . Referring to  FIG. 8A , the pushing member  200  is rotated rightwards by a jig (not shown) whose front end is inserted in the jig receivers  214 .  FIG. 8B  shows a state of the inside of the accommodation section  104 . Referring to  FIG. 8B , each lock protrusion  212  traverses the back surface of the corresponding retaining section  116  to move from one side surface of the corresponding retaining section  116  to the other side surface of the corresponding retaining section  116 , so that each lock section  220  moves exactly to the position where it opposes the back surface of the corresponding retaining section  116 . 
         [0045]      FIGS. 9A and 9B  show a state in which the pushing of the pushing member into the accommodation section from the state shown in  FIGS. 8A and 8B  is stopped, and the pushing member is mounted in an end portion of the optical connector.  FIG. 9A  shows a state in which the pushing member  200  is mounted in the end portion of the accommodation section  104 . The pushing member  200  is subjected to a force that urges the pushing member  200  in a push-out direction by the coil spring  202  in the accommodation section  104 , and is fixed to the end portion of the accommodation section  104 . 
         [0046]      FIG. 9B  shows a state of the inside of the accommodation section  104  after the pushing member  200  has been mounted. The pushing member  200  is subjected to an elastic force of the coil spring  202 , and the back surfaces of the retaining sections  116  are fixed by being pushed against the respective lock sections  220 . Each lock protrusion  212  that has traversed the back surface of the corresponding retaining section  116  from the one side surface of the corresponding retaining section  116  to the other side surface of the corresponding retaining section  116  is such that the lock sections  220  and the lock protrusions  212  surround the back-surface sides of the retaining sections  116 . When the optical connector  100  is twisted clockwise or counterclockwise with respect to the axial direction, the rotation caused by the twisting or the like of the optical connector  100  can be restricted as a result of the lock protrusions  212  on the lock sections  220  coming into contact with the retaining sections  116 . 
         [0047]    The optical connector according to the present invention can be used when connecting cables in, for example, an optical fiber cable laying construction.