Optical Connector

Abstract

To provide an optical connector capable of reducing the frequency of occurrences of retraction of a ferrule into a housing.SOLUTION: An optical connector comprises a ferrule that can hold an optical fiber at a front end and a front housing that accommodates the ferrule. The ferrule includes a flange portion having a regular hexagonal prism shape, and the front housing includes a through-hole into which the flange portion is inserted. The through-hole has a first hole portion in which a cross section perpendicular to a first direction is a regular hexagonal shape and a second hole portion that is continuous from the first hole portion. In a cross section perpendicular to the first direction at an end of a rear end side of the second hole portion, six contours corresponding to each side of an end of a front end side of the second hole portion bulge outward or inward; a minimum diameter of the end of the rear end side of the second hole portion is longer than the longest diagonal line of the flange portion; and the second hole portion is continuously reduced in diameter from the end of the rear end side toward the end of the front end side.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to optical connectors. [Background technology]

[0002] Optical connectors are disclosed in Patent Documents 1 to 3. The optical connector includes a ferrule and a front housing that accommodates the ferrule. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-56420 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-147345 [Patent Document 3] Special Publication No. 2013-522679 Summary of the Invention [Problem to be solved by the invention]

[0004] The optical connector described in Patent Document 1 includes a ferrule having a flange with a hexagonal portion and a housing having a hexagonal recessed portion. In this optical connector, when the ferrule flange is properly fitted into the recessed portion, rotation of the ferrule is restricted. Furthermore, the rotation angle of the ferrule can be changed by rotating the ferrule while it is pressed into the housing. Even if the center of the tip of the optical fiber is offset from the center line of the optical connector, the center position of the tip of the optical fiber can be brought closer to the center line of the optical connector by changing the rotation angle of the ferrule.

[0005] Generally, the length of the longest diagonal of the flange in a cross section perpendicular to the axial direction is longer than the distance between opposite sides of the recessed portion in a cross section perpendicular to the axial direction. Therefore, for example, the corners of the hexagonal shape of the flange may get caught on the edges of the hexagonal shape of the recessed portion, preventing the flange from fitting into the recessed portion. This situation can occur, for example, when manufacturing optical connectors in a factory, pushing the ferrule of a completed optical connector into the housing and adjusting its rotation, or when the ferrule is pushed into the housing while cleaning the tip of the optical fiber with a cleaner. In this situation, the ferrule remains retracted into the housing, so the length of the ferrule protruding from the housing is shorter than the design value, preventing the ferrule from contacting the mating ferrule. This retracted state must be corrected, which is a time-consuming process.

[0006] An object of the present disclosure is to provide an optical connector that can reduce the frequency with which a ferrule gets pulled into a housing. [Means for solving the problem]

[0007] The present disclosure provides an optical connector having a front end and a rear end opposite the front end in a first direction, and into which an optical fiber can be inserted from the rear end. The optical connector includes a ferrule capable of holding an optical fiber at the front end and a front housing that houses the ferrule. The ferrule has a flange portion shaped like a regular hexagonal prism. The front housing has a through hole into which the flange portion is inserted. The through hole has a regular hexagonal cross section perpendicular to the first direction, a diameter of which continuously decreases from the rear end to the front end, a first hole portion whose longest diagonal at the front end is shorter than that of the flange portion, a longest diagonal at the rear end is longer than that of the flange portion, and a distance between opposite sides at the rear end is shorter than that of the flange portion; and a second hole portion located rearward of the first hole portion in the first direction and continuous with the first hole portion. The cross section of the second hole portion perpendicular to the first direction at the front end end is the same as the cross section of the first hole portion perpendicular to the first direction at the rear end end. In a cross section perpendicular to the first direction at the rear end of the second hole portion, six contours corresponding to each side at the front end of the second hole portion bulge outward or inward, and the minimum diameter of the rear end of the second hole portion is longer than the longest diagonal line of the flange portion. The diameter of the second hole portion continuously decreases from the rear end to the front end. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide an optical connector that can reduce the frequency with which the ferrule gets pulled into the housing. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing an optical connector according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing a state in which the optical connector shown in FIG. 1 is inserted into a mounting port of an adapter. [Figure 3] FIG. 3 is an exploded perspective view of the optical connector shown in FIG. [Figure 4] FIG. 4 is a perspective view showing an outer housing with a latch, which is one component of the optical connector. [Figure 5] FIG. 5 is a perspective view showing a tab which is one of the components of the optical connector. [Figure 6] FIG. 6 is a perspective view of the tab shown in FIG. 5 as seen from the opposite side. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is a view showing a cross section perpendicular to the longitudinal direction of the flange portion. [Figure 9] FIG. 9 is a cross-sectional view showing only the front housing of the configuration shown in FIG. [Figure 10] FIG. 10 is a cutaway perspective view taken along line XX in FIG. [Figure 11] FIG. 11 is a cross-sectional view showing the configuration of a front housing according to a modified example. [Figure 12] FIG. 12 is a cutaway perspective view taken along line XII-XII in FIG. [Figure 13] FIG. 13 is a diagram showing a star-shaped hexagon. [Figure 14] FIG. 14 is a diagram schematically showing a cross section taken along line XIV-XIV in FIG. [Figure 15] FIG. 15 is a diagram schematically showing a cross section taken along line XV-XV in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Description of the embodiments of the present disclosure] First, the details of the embodiments of the present disclosure will be listed and described. An optical connector according to one embodiment has a front end and a rear end opposite the front end in a first direction, and allows an optical fiber to be inserted from the rear end. The optical connector includes a ferrule capable of holding an optical fiber at the front end and a front housing that houses the ferrule. The ferrule has a flange portion shaped like a regular hexagonal prism. The front housing has a through hole into which the flange portion is inserted. The through hole has a regular hexagonal cross section perpendicular to the first direction, and the diameter of the through hole continuously decreases from the rear end side to the front end side. The through hole has a first hole portion whose longest diagonal at the front end side is shorter than that of the flange portion, whose longest diagonal at the rear end side is longer than that of the flange portion, and whose distance between opposite sides at the rear end side is shorter than that of the flange portion; and a second hole portion located on the rear end side in the first direction relative to the first hole portion and continuous with the first hole portion. The shape of a cross section perpendicular to the first direction at the front end of the second hole portion is identical to the shape of a cross section perpendicular to the first direction at the rear end of the first hole portion. In the cross section perpendicular to the first direction at the rear end of the second hole portion, six contours corresponding to each side at the front end of the second hole portion bulge outward or inward, and the minimum diameter at the rear end of the second hole portion is longer than the longest diagonal line of the flange portion. The diameter of the second hole portion continuously decreases from the rear end to the front end.

[0011] In this optical connector, the minimum diameter of the rear end of the second hole portion in a cross section perpendicular to the first direction is longer than the longest diagonal of the flange portion. Therefore, when the flange portion passes through the rear end of the second hole portion, the flange portion is smoothly inserted into the through hole without hitting the contour of the rear end of the second hole portion. In this optical connector, six contours corresponding to each side of the front end of the second hole portion in the cross section bulge outward or inward, and the diameter of the second hole portion continuously decreases from the rear end to the front end. Therefore, as the flange portion is further inserted, the angle around the central axis of the flange portion changes in accordance with the slopes between the six contours and each side of the front end of the second hole portion, so that the corners of the flange portion, which are the vertices of the regular hexagonal shape of the cross section perpendicular to the first direction of the flange portion, align with the vertices of the regular hexagonal shape of the front end of the second hole portion. Therefore, when manufacturing optical connectors at a factory or the like, when a ferrule of a completed optical connector is pushed into the front housing and rotated, or when a ferrule is pushed into the front housing when cleaning the tip of an optical fiber with a cleaner, the corners of the flange portion are prevented from getting caught on the rear end of the second hole portion when the ferrule is pulled out. As a result, the frequency of ferrule pull-in is reduced. In this optical connector, the cross section of the first hole portion perpendicular to the first direction is a regular hexagon, and the first hole portion continuously reduces in diameter from the rear end to the front end, with the longest diagonal at the front end being shorter than the longest diagonal of the flange portion and the longest diagonal at the rear end being longer than the longest diagonal of the flange portion. Therefore, the flange portion is inserted with the corners of the flange portion and the vertices of the regular hexagonal shape of the cross section of the first hole portion perpendicular to the first direction aligned, and is ultimately fitted into the first hole portion, thereby restricting rotation of the flange portion around the axis of the through hole.

[0012] In one embodiment, the cross section perpendicular to the first direction at the rear end of the second hole portion may have a circular shape. In this case, in the cross section perpendicular to the first direction at the rear end of the second hole portion, six contours corresponding to the sides at the front end of the second hole portion can be realized with a simple shape that bulges outward, thereby improving ease of processing the housing.

[0013] In one embodiment, the cross section perpendicular to the first direction at the rear end of the second hole portion may have a generally star-shaped configuration. In this case, in the cross section perpendicular to the first direction at the rear end of the second hole portion, six contours corresponding to the sides at the front end of the second hole portion can be realized in a simple shape, thereby making it easier to process the housing.

[0014] [Details of the embodiments of the present disclosure] Specific examples of embodiments of the present disclosure will be described below with reference to the drawings. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. In the description of the drawings, the same elements are given the same reference numerals, and duplicate explanations will be omitted.

[0015] FIG. 1 is a perspective view showing an optical connector according to one embodiment. As shown in FIG. 1, the optical connector 1 is a connector that is elongated horizontally in a longitudinal direction X (first direction) and has a front end 1a and a rear end 1b. The rear end 1b is located on the opposite side of the front end 1a in the longitudinal direction X. An optical cable K held by the optical connector 1 is inserted from the rear end 1b of the optical connector 1. A pair of optical fibers (not shown) contained in the optical cable K have their coating resin removed inside the optical connector 1, and are housed and held in a pair of ferrules 14, 15, respectively. The optical connector 1 is, for example, a duplex LC connector and a uniboot type optical connector. The optical connector 1 may be an optical connector with another configuration.

[0016] 2 is a perspective view showing the optical connector 1 inserted into a mounting port of an adapter 100 (external device). Another optical connector (not shown) is inserted into the mounting port on the opposite side of the adapter 100 from the optical connector 1, and the optical connector 1 is optically coupled to the other optical connector by the adapter 100. The optical connector 1 may be configured to be inserted into a connecting portion of an optical transceiver or the like as an external device. In this case, the external device may be made of metal.

[0017] Fig. 3 is an exploded perspective view of the optical connector shown in Fig. 1. As shown in Fig. 1 and Fig. 3, the optical connector 1 includes a pair of front housings 10, 11, an inner housing 20, an outer housing 30, a latch 40, a tab 50, a boot 60, an elastic member 70, and a cable holding member 80.

[0018] The pair of front housings 10, 11 each include a main body 12, 13 and a ferrule 14, 15. The main body 12, 13 is made of synthetic resin and has a rectangular prism-like outer shape with a circular hole 12a, 13a formed therein. The main body 12, 13 accommodates a ferrule 14, 15 capable of holding an optical fiber in the circular hole 12a, 13a so that the tip 14a, 15a of each ferrule is exposed to the outside at the front end 1a of the optical connector 1. The tip of the held optical fiber is exposed from the tip 14a, 15a of the ferrule 14, 15. The tip 14a, 15a of the ferrule 14, 15 may be parallel to or inclined from the vertical direction Z, which is perpendicular to (intersects with) the longitudinal direction X. The configuration of the ferrule 14, 15 will be described in more detail later. The main body 12, 13 has protrusions 12b, 13b at the four corners of the rear end of each of the main bodies 12, 13. These protrusions 12b, 13b determine the relative position of the front housings 10, 11 when they are connected to the front end of the inner housing 20. A pair of rectangular openings 16 are provided on both side surfaces of the front housing 10, and a pair of rectangular openings 17 are provided on both side surfaces of the front housing 11. Through holes 18, 19 shown in Figures 8 and 9 are provided inside the front housings 10, 11. The configurations of the through holes 18, 19 will be described in more detail below.

[0019] The inner housing 20 is a housing formed with an internal space capable of accommodating an optical fiber and is made of synthetic resin. The inner housing 20 has a front end 21, a tapered portion 22, and a rear end 23, and is formed so that the internal space of each gradually widens from the rear end to the front end. The inner housing 20 is a region for branching a pair of optical fibers contained in the optical cable K into ferrules 14, 15, and is connected to the rear ends of the pair of front housings 10, 11. The front end 21 of the inner housing 20 is provided with a pair of latches 24 and a pair of latches 25. The pair of latches 24 are inserted from the inside into and engage with the pair of openings 16 of the front housing 10, and the pair of latches 25 are inserted from the inside into and engage with the pair of openings 17 of the front housing 11. This allows the pair of front housings 10, 11 to be connected to the inner housing 20. The inner housing 20 also has protrusions 26 on both the front and back surfaces, respectively, near the center and slightly forward. When the inner housing 20 is housed in the outer housing 30, one of the protrusions 26 engages with a hole provided in the lower surface 30b of the outer housing 30, thereby detachably connecting the inner housing 20 to the inside of the outer housing 30. Each protrusion 26 has an inclined surface to allow for detachment.

[0020] The outer housing 30 is a housing that accommodates the inner housing 20 and is connected to the inner housing 20. FIG. 4 is a perspective view showing the outer housing 30 with a latch, which is one component of the optical connector. As shown in FIG. 4, in this embodiment, the outer housing 30 is formed from synthetic resin so as to be integrated with the latch 40, which will be described later. However, the outer housing 30 and the latch 40 may be formed as separate bodies and then connected to each other by a predetermined means (such as adhesion or fitting). In FIG. 4, the latch 40 is connected to the outer housing 30 at a connecting portion A. As shown in FIG. 4, the outer housing 30 has a housing main body 33 having openings 31 and 32 at the front and rear, respectively.

[0021] The upper surface 30a of the outer housing 30 is provided with a pair of wall portions 36 defining a portion 36a for accommodating an elastic member 70 therein, and a pair of guide protrusions 37 located outside the wall portions 36. The elastic member 70 housed in the portion 36a is disposed between the outer housing 30 and a tab 50 (described later) and functions to return the tab 50 to its normal position when the tab 50 is moved toward the rear end 1b of the optical connector 1 relative to the outer housing 30. The elastic member 70 is, for example, a spring. When the tab 50 is connected to the outer housing 30, each guide protrusion 37 is positioned within a slit 55, 56 (see FIG. 5) of the tab 50 to guide the movement of the tab 50 along the longitudinal direction X. The outer housing 30 further includes a protrusion 34 on the front side and a slit 35 for connection below each guide protrusion 37 as a connection structure with the tab 50. A hole and an opening are provided on the lower surface 30b of the outer housing 30. The projection 26 on one side of the inner housing 20 is adapted to fit into the hole, thereby detachably connecting the inner housing 20 to the outer housing 30.

[0022] The latch 40 is a component provided outside the outer housing 30 and includes members 41 and 42 extending from a base end 40a, where the coupling portion A is located, toward the front end 1a along the longitudinal direction X. The members 41 and 42 of the latch 40 have engagement portions 43 and 44 at their tip portions 40b that can engage with an external device such as the adapter 100. Each of the engagement portions 43 and 44 includes a pair of protrusions that protrude outward, for example, perpendicular to the longitudinal direction X. The optical connector 1 is attached to the adapter 100 by engaging these protrusions of the engagement portions 43 and 44 with engagement portions within the adapter 100. In a normal state, the tip portions 40b of the latch 40, i.e., the engagement portions 43 and 44, are spaced apart from the front housings 10 and float.

[0023] The latch 40's components 41 and 42 are provided with inclined surfaces 41a and 42a, inclined surfaces 41b and 42b, and recesses 41c and 42c near their centers. The inclined surfaces 41a and 42a are provided on the inside of the latch 40. The inclined surfaces 41b and 42b are provided on the outside of the latch 40 and form part of the recesses 41c and 42c. The latch 40's components 41 and 42 may be formed to have the same overall thickness, or the thickness of the base end 40a may be thinner than the thickness of the regions where the inclined surfaces 41a and 42a or the inclined surfaces 41b and 42b are located. In this case, the distal end 40b of the latch 40, i.e., the engagement portions 43 and 44, can move more smoothly up and down with the base end 40a as a fulcrum. The "thickness" here refers to the thickness in the direction perpendicular to the surface at each location.

[0024] The tab 50 is disposed outside the latch 40 so as to cover the latch 40 except for the engagement portions 43 and 44 at the tip portion 40b. FIG. 5 is a perspective view showing a tab, which is a component of an optical connector, and FIG. 6 is a perspective view of the tab shown in FIG. 5, viewed from the opposite side. As shown in FIGS. 3, 4, 5, and 6, a protrusion 58 on the inside of the front end 50a of the tab 50 is connected to the protrusion 34 on the top surface 30a of the outer housing 30, and a pair of latches 59 on the left and right sides of the inside of the tab 50 are caught from the inside in slits 35 on the left and right sides of the top surface 30a of the outer housing 30. This connects the tab 50 to the outer housing 30 so as to be movable along the longitudinal direction X relative to the outer housing 30. The tab 50 is configured to push the engagement portions 43 and 44 of the latch 40 downward toward the front housings 10 and 11 in the up-down direction Z as the tab 50 moves from the front end 1a toward the rear end 1b along the longitudinal direction X. More specifically, the front end 50a of the tab 50 has downwardly protruding protrusions 51, 52, and when the tab 50 moves rearward, these protrusions 51, 52 move rearward along the inclined surfaces 41b, 42b of the latch 40, thereby pushing the engagement portions 43, 44 of the latch 40 downward.

[0025] A pair of protrusions 53, 54 are further provided on the inside of the tab 50. These protrusions 53, 54 are positioned so that they do not come into slight contact with the inside of the latch 40 under normal conditions, but when the optical connector 1 is attached to the adapter 100, that is, when the engaging portions 43, 44 of the latch 40 are engaged with the engaging portions of the adapter 100, the engaging portions 43, 44 of the latch 40 move slightly downward, so that they come into contact with the inside of the latch 40. The latch 40 is configured so that the engaging portions 43, 44 are pushed down toward the front housings 10, 11, using the contact points with these protrusions 53, 54 as fulcrums.

[0026] A pair of slits 55, 56 are provided in the center of the tab 50. The pair of guide protrusions 37 of the outer housing 30 described above are disposed in these slits 55, 56. The pair of guide protrusions 37 slide within the slits 55, 56, respectively, thereby guiding the movement of the tab 50 along the longitudinal direction X. A grip portion 57 is provided at the rear end 50b of the tab 50. When removing the optical connector 1 attached to the adapter 100 from the adapter 100, the user grips the grip portion 57 and pulls it rearward, causing the protrusions 51, 52 to perform the above-described operation, thereby disengaging the latch 40. In this embodiment, the grip portion 57 has a cylindrical shape that can be rotated once so that the user can grip it in both the vertical and horizontal directions. However, any other configuration may be used as long as it can be gripped in at least one of the vertical and horizontal directions. A boot 60, which will be described later, is housed inside the grip portion 57.

[0027] The boot 60 and the cable holding member 80 are members for introducing the optical cable K into the optical connector 1 and for fixing the optical cable K at a predetermined position within the optical connector 1. This allows the optical fiber contained in the optical cable K to be inserted from the rear end 1b of the optical connector 1. A part of the boot 60 and the cable holding member 80 are housed inside the outer housing 30 or the like.

[0028] Here, the attachment structure of the ferrule 14 to the front housing 10 in the optical connector 1 configured as described above will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 1. The ferrule 14 extends in the longitudinal direction X when attached to the front housing 10. The ferrule 14 holds the optical fiber extending forward from the optical cable K with the optical fiber exposed at the tip 14a. The ferrule 14 has a ferrule body 14b located on the front end side in the longitudinal direction X, and a metal member 14c located on the rear end side, into which the ferrule body 14b is inserted and fixed.

[0029] A through-hole 141 extending in the longitudinal direction X and having a circular cross section perpendicular to the longitudinal direction X is provided inside the ferrule body 14b. The through-hole 141 includes a first portion 141a extending from the front end to the rear end of the ferrule body 14b and a second portion 141b extending from the first portion 141a to the rear end of the ferrule body 14b. The diameter of the first portion 141a is slightly larger than the outer diameter of the optical fiber, and the periphery of the optical fiber is supported by the first portion 141a, thereby stably holding the optical fiber. The diameter of a through-hole 142 provided in the metal member 14c (described later) is larger than the diameter of the first portion 141a of the through-hole provided in the ferrule body 14b. Therefore, the second portion 141b of the through-hole is a conical hole whose diameter decreases from the rear end of the ferrule body 14b toward the first portion 141a.

[0030] The metal member 14c has a flange portion 14d located at the front end in the longitudinal direction X and a hollow tubular portion 14e located at the rear end in the longitudinal direction X and connected to the flange portion 14d. The flange portion 14d is inserted into and held in a through-hole 18 of the front housing 10. The flange portion 14d has a regular hexagonal column portion 14f and a tapered portion 14g whose diameter decreases from the front end of the regular hexagonal column portion 14f toward the front end of the ferrule body 14b. The tapered portion 14g has a cross section perpendicular to the longitudinal direction X that is, for example, circular. FIG. 8 is a diagram showing a cross section perpendicular to the longitudinal direction X of the regular hexagonal column portion 14f of the flange portion 14d. In the following description, the diameter d1 of the regular hexagonal column portion 14f refers to the distance between two vertices of the regular hexagonal column portion 14f that are included in the shape of a regular hexagon in a cross section perpendicular to the longitudinal direction X. A through-hole 142 having a circular cross section perpendicular to the longitudinal direction X is provided inside the metal member 14c. As shown in Fig. 7, the through-hole 142 has a diameter that is approximately equal to the outer diameter of the ferrule body 14b in a portion on its front end side, and a diameter that is smaller than the outer diameter of the ferrule body 14b in the remaining portion on its rear end side.

[0031] One of the coated fibers branched from the optical cable K is inserted into the through hole 142 of the metal member 14c. The diameter of this through hole 142 is slightly larger than the outer diameter of the coated fiber. The periphery of the coated fiber is supported by the through hole 142, thereby holding the coated fiber. The front housing 10 has an elastic member 14h provided around the axis of the hollow tubular portion 14e. The elastic member 14h is, for example, a compression coil spring. The elastic member 14h is sandwiched between a step provided between the flange portion 14d and the hollow tubular portion 14e and the front end portion 21 of the inner housing 20, thereby applying a force that pushes the ferrule 14 forward in the longitudinal direction X.

[0032] FIG. 9 is a cross-sectional view showing only the front housing 10 of the configuration shown in FIG. 7. FIG. 10 is a cutaway perspective view taken along line XX in FIG. 9. As shown in FIGS. 9 and 10, the front housing 10 is provided with a through-hole 18 extending in the longitudinal direction X. The through-hole 18 has a hole portion 84, a hole portion 81 (first hole portion), a hole portion 82 (second hole portion), and a hole portion 85 extending along the longitudinal direction X. The hole portion 81 is located closer to the front end of the through-hole 18, and the hole portion 82 is located between the hole portion 81 and the rear end of the through-hole 18. The hole portion 84 is located between the hole portion 81 and the front end of the through-hole 18, and the hole portion 85 is located between the hole portion 82 and the rear end of the through-hole 18. The hole portion 81 and the hole portion 82 share the same axis A1. The hole portion 81 has an end 81a on the front end 1a side and an end 81b on the rear end 1b side. The hole 82 has an end 82a on the front end 1a side and an end 82b on the rear end 1b side. In the following description, the shapes of the end 81a, the end 81b, the end 82a, and the end 82b refer to the shapes of the cross sections perpendicular to the longitudinal direction X of the ends 81a, 81b, 82a, and 82b, respectively.

[0033] A cross section of the hole 81 perpendicular to the longitudinal direction X has a regular hexagonal shape. The hole 81 continuously reduces in diameter from the end 81b to the end 81a in the longitudinal direction X. In this disclosure, "reduced diameter" refers to the diameter of the cross section perpendicular to the longitudinal direction X becoming smaller from one end to the other in the longitudinal direction X, and refers to the overall reduction in the outline of the cross section. Therefore, when comparing a cross section with a cross section after the diameter of the cross section has been reduced, the cross section after the diameter has been reduced is one size smaller than the cross section. The cross sections of the end 81a and the end 81b perpendicular to the longitudinal direction X have a regular hexagonal shape, and the diameter D1 of the end 81a is smaller than the diameter D2 of the end 81b. The diameter D1 of the end 81a and the diameter D2 of the end 81b refer to the distance between two vertices that sandwich the axis A1 of the hole 81 and are included in the regular hexagonal shape of a cross section of the end 81a and the end 81b that is perpendicular to the longitudinal direction X. The diameter D1 of the end 81a is larger than the diameter of the front end of the tapered portion 14g and smaller than the diameter d1 of the front end of the regular hexagonal prism portion 14f. In other words, the diameter D1 of the end 81a is shorter than the longest diagonal line L (see FIG. 8) of the flange portion 14d. The longest diagonal line L of the flange portion 14d refers to the line segment that connects two vertices that sandwich the axis G of the regular hexagonal prism portion 14f and are included in the regular hexagonal shape of a cross section of the regular hexagonal prism portion 14f that is perpendicular to the longitudinal direction X. In other words, the length of the longest diagonal line L of the flange portion 14d is equal to the diameter d1 of the regular hexagonal prism portion 14f. The diameter D2 of the end 81b is larger than the diameter d1 of the regular hexagonal column portion 14f. That is, the diameter D2 of the end 81b is longer than the longest diagonal line L of the flange portion 14d. The distance D3 between opposite sides of the shape of the end 81b is shorter than the longest diagonal line L of the flange portion 14d.

[0034] The shapes of the end 82a and the end 81b are regular hexagons. The diameter of the end 82a is equal to the diameter D2 of the end 81b. That is, the shape and size of the end 82a are identical to the shape and size of the end 81b. Therefore, the inner walls of the hole 81 and the hole 82 are continuous with each other. The diameter of the hole 82 continuously decreases from the end 82b to the end 82a in the longitudinal direction X. At the end 82b, six contours S2 corresponding to each side S1 of the end 82a bulge outward from the end 82b in a cross section perpendicular to the axis A1. In one example, the shape of the end 82b is a circle with a radius slightly larger than the radius of the circumscribing circle for the shape of the end 81b. The minimum diameter of the end 82b is longer than the longest diagonal line L of the flange portion 14d. The minimum diameter of the end 82b refers to the diameter of the inscribed circle of the shape of the end 82b in a cross section perpendicular to the longitudinal direction X of the end 82b. Because the shape of the end 82b is circular, the minimum diameter of the end 82b refers to the diameter of the end 82b. The inclination angle of the generatrix g1 of the hole 82, which extends from each vertex of the shape of the end 82a, relative to the axis A1 of the hole 82, is the smallest among the inclination angles of the generatrix g2 of the hole 82, which extends from the midpoint of each side of the shape of the end 82a, relative to the axis A1 of the hole 82, is the largest among the inclination angles of the generatrix g2 of the hole 82 relative to the axis A1 of the hole 82. The generatrix g2 of the hole 82 refers to the contour line of the hole 82 when the hole 82 is cut along a cross section that includes the axis A1 of the hole 82 and is parallel to the axis A1 of the hole 82.

[0035] When the ferrule 14 is inserted into the through hole 18, the ferrule body 14b, the tapered portion 14g, and the flange portion 14d are inserted into the through hole 18 in this order. At this time, the ferrule 14 is inserted into the through hole 18 with the axis of the ferrule 14 (axis G of the flange portion 14d) aligned with the axis A1 of the through hole 18. Because the outer diameter of the ferrule body 14b is smaller than the distance between opposite sides of the end 81a, the ferrule body 14b passes through the hole 81 and protrudes from the end 81a toward the front end. Because the diameter of the rear end of the tapered portion 14g is smaller than the distance D3 between opposite sides of the end 82a, the tapered portion 14g can pass through the hole 82. Because the longest diagonal line L of the flange portion 14d is shorter than the smallest diameter of the end 82b (the diameter of the end 82b in this embodiment), the flange portion 14d can pass through the end 82b regardless of the rotation angle of the flange portion 14d around the axis A1. As the flange portion 14d is inserted into the hole 82, the diameter of the hole 82 gradually decreases. Because the distance D3 between opposite sides of the end 82a is shorter than the longest diagonal line L of the flange portion 14d, the corners of the flange portion 14d may come into contact with the wall surface of the hole 82 depending on the rotation angle of the flange portion 14d around the axis A1. Note that the corners of the flange portion 14d refer to the portions including the vertices of a regular hexagon in a cross section perpendicular to the longitudinal direction X of the regular hexagonal column portion 14f. In this way, when the corners of the flange portion 14d come into contact with the wall surface of the hole 82, the pressing force of the elastic member 14h causes the flange portion 14d to automatically rotate around the axis A1, following the wall surface (slope) of the hole 82, and the corners of the flange portion 14d come into contact with the vertex of the end 82a, thereby eliminating the contact of the corners of the flange portion 14d with the wall surface of the hole 82. Thereafter, the tapered portion 14g comes into contact with the hole 81, and the ferrule 14 comes to rest. Specifically, the tapered portion 14g comes to rest in the hole 81 in a state in which the end 81a overlaps with a cross section of the tapered portion 14g perpendicular to the longitudinal direction X, the cross section being located between the front end and the rear end of the tapered portion 14g, and having a diameter equal to the diameter D1 of the end 81a, in the longitudinal direction X.

[0036] In the optical connector 1 configured as described above, the structure for attaching the ferrule 15 to the front housing 11 and the operation when attaching it are the same as the structure for attaching the ferrule 14 to the front housing 10 and the operation when attaching it. That is, the structure of the ferrule 15 is the same as the structure of the ferrule 14. Furthermore, the structure of the front housing 11 is the same as the structure of the front housing 10.

[0037] As described above, in the optical connector 1 according to this embodiment, the minimum diameter of the end 82b is longer than the longest diagonal line L of the flange portion 14d. Therefore, when the flange portion 14d passes through the end 82b, the flange portion 14d is smoothly inserted into the hole 82 without hitting the contour of the end 82b. In the optical connector 1, the six contours S2 in the shape of the end 82b that correspond to the sides S1 in the shape of the end 82a bulge outward, and the diameter of the hole 82 continuously decreases from the end 82b to the end 82a. Therefore, as the flange portion 14d is further inserted, the flange portion 14d rotates along the slopes between the six contours S2 and the sides S1 on the front end side of the hole 82, so that the corners of the flange portion 14d align with the vertices of the shape of the end 82a. Therefore, when the optical connector 1 is manufactured in a factory or the like, and the ferrule 14 of the completed optical connector 1 is pushed into the housing and rotated for adjustment, or when the ferrule 14 is pushed into the housing when cleaning the tip of an optical fiber with a cleaner, the corners of the flange portion 14d are prevented from getting caught on the end 82b of the hole 82 when the ferrule 14 is pulled out. As a result, the frequency of the ferrule 14 being pulled out is reduced. In the optical connector 1, the cross section of the hole 81 perpendicular to the longitudinal direction X is a regular hexagon, and the diameter continuously decreases from the end 81b to the end 81a, and the diameter D1 of the end 81a is shorter than the longest diagonal line L of the flange portion 14d, and the diameter D2 of the end 81b is longer than the longest diagonal line L of the flange portion 14d. Therefore, the flange portion 14d is inserted with the corners of the flange portion 14d aligned with the vertices of the regular hexagonal cross section of the hole 81 perpendicular to the longitudinal direction X, and is ultimately fitted into the hole 81, thereby restricting the flange portion 14d from rotating around the axis of the through-hole 18. In the optical connector 1, the cross section of the end 82b perpendicular to the longitudinal direction X is circular, so that the six contours S2 corresponding to the sides S1 of the end 82a can be realized with a simple shape, bulging outward. This improves the ease of processing the front housing 10. All of the same effects as those described above can be obtained when the ferrule 15 is attached to the front housing 11.

[0038] [Variations] Fig. 11 is a cross-sectional view showing the configuration of a front housing 10A according to a modified example of the embodiment. Fig. 12 is a cutaway perspective view taken along line XII-XII in Fig. 11. The front housing 10A according to the modified example differs from the embodiment described above mainly in the shape of the rear end of the through-hole 18. The through-hole 18 of the front housing 10A according to this modified example has a hole 83 instead of the hole 82 according to the embodiment described above.

[0039] As shown in FIGS. 11 and 12 , the front housing 10A is provided with a through hole 18 extending in the longitudinal direction X. The through hole 18 has a hole portion 84, a hole portion 81, a hole portion 83, and a hole portion 85 extending along the longitudinal direction X. The hole portion 81 is located closer to the front end of the through hole 18, and the hole portion 83 is located between the hole portion 81 and the rear end of the through hole 18. The hole portion 84 is located between the hole portion 81 and the front end of the through hole 18, and the hole portion 85 is located between the hole portion 83 and the rear end of the through hole 18. The hole portion 81 and the hole portion 83 share the same axis A2. The hole portion 81 has an end 81a on the front end 1a side and an end 81b on the rear end 1b side. The hole portion 83 has an end 83a on the front end 1a side and an end 83b on the rear end 1b side. In the following description, the shapes of the ends 83a and 83b refer to the cross-sectional shapes of the ends 83a and 83b, respectively, perpendicular to the longitudinal direction X. The configuration of the hole 81 is the same as in the above embodiment.

[0040] The shape of the end 83a is a regular hexagon. The diameter of the end 83a is equal to the diameter D2 of the end 81b (see FIG. 10). That is, the shape and size of the end 83a are identical to the shape and size of the end 81b. Therefore, the inner walls of the hole 81 and the hole 83 are continuous with each other. The diameter of the hole 83 continuously decreases from the end 83b toward the end 83a in the longitudinal direction X. At the end 83b, six contours S3 corresponding to each side S1 at the end 83a bulge toward the inside of the end 83b in a cross section perpendicular to the axis A2. In one example, the shape of the end 83b is approximately star-shaped. However, it does not have to be strictly star-shaped; for example, the apex of the star may be flattened. FIG. 13 shows a star-shaped hexagon SH. This star-shaped hexagon SH has six vertices Q1 corresponding to the vertices of the outer regular hexagon H1, and six vertices Q2 corresponding to the vertices of an inner regular hexagon H2, which is a regular hexagon smaller than the outer regular hexagon H1 and rotated 30° around the central axis relative to the outer regular hexagon H1. This star-shaped hexagon SH has a shape in which these vertices Q1 and Q2 are alternately connected by straight lines. The end 83b has a shape in which each vertex Q1 of the star-shaped hexagon SH shown in FIG. 13 is crushed by a hole 85. The minimum diameter D4 of the end 83b shown in FIG. 12 (corresponding to the distance between two vertices Q2 facing each other across the central axis of the star-shaped hexagon SH) is longer than the longest diagonal line L of the flange portion 14d. Furthermore, the hole 83 of this modified example is reduced in diameter in two stages. That is, the hole 83 has a first portion 831 including the end 83a and a second portion 832 including the end 83b. The first portion 831 and the second portion 832 are aligned along the axis A2 and connected to each other. FIG. 14 is a schematic cross-sectional view taken along line XIV-XIV in FIG. 12 , showing a cross-section parallel to the axis A2 that includes two vertices of the end 83b corresponding to the two opposing vertices Q1 of the star-shaped hexagon SH. FIG. 15 is a schematic cross-sectional view taken along line XV-XV in FIG. 12 , showing a cross-section parallel to the axis A2 that includes two vertices of the end 83b corresponding to the two opposing vertices Q2 of the star-shaped hexagon SH. As shown in FIG. 14 , the inclination angle of the generatrix g3 of the hole 83 extending from each vertex of the end 83b corresponding to the vertex Q1 is inclined with respect to the axis A2 in both the first portion 831 and the second portion 832.In the first portion 831, the inclination angle of the generatrix g3 with respect to the axis A2 is the largest among the inclination angles of the generatrix with respect to the axis A2. Also, as shown in FIG. 15 , the inclination angle of the generatrix g4 of the hole 83 extending from each vertex of the end 83b corresponding to the vertex Q2 is inclined or parallel to the axis A2 in the first portion 831, and is inclined with respect to the axis A2 in the second portion 832. In the first portion 831, the inclination angle of the generatrix g4 with respect to the axis A2 is the smallest among the inclination angles of the generatrix with respect to the axis A2. Note that the generatrix of the hole 83 refers to the outline of the hole 83 when the hole 83 is cut in a cross section that includes the axis A2 of the hole 83 and is parallel to the axis A2 of the hole 83.

[0041] When the ferrule 14 is inserted into the through hole 18, the ferrule body 14b, the tapered portion 14g, and the flange portion 14d are inserted into the through hole 18 in this order. At this time, the ferrule 14 is inserted into the through hole 18 with the axis of the ferrule 14 (axis G of the flange portion 14d) aligned with the axis A2 of the through hole 18. Because the outer diameter of the ferrule body 14b is smaller than the distance between opposite sides of the end 81a, the ferrule body 14b passes through the hole 81 and protrudes from the end 81a toward the front end. Because the diameter of the rear end of the tapered portion 14g is smaller than the distance D3 between opposite sides of the end 83a, the tapered portion 14g can pass through the hole 83. Because the longest diagonal line L of the flange portion 14d is shorter than the minimum diameter D4 of the end 83b, the flange portion 14d can pass through the end 83b regardless of the rotation angle of the flange portion 14d around its axis. As the flange portion 14d is inserted into the hole 83, the diameter of the hole 83 gradually decreases. Because the distance between opposite sides of the end 83a is shorter than the longest diagonal line L of the flange portion 14d, the corners of the flange portion 14d may come into contact with the wall surface of the hole 83 depending on the rotation angle of the flange portion 14d around the axis A2. When the corners of the flange portion 14d come into contact with the wall surface of the hole 83, the pressing force of the elastic member 14h causes the flange portion 14d to automatically rotate around the axis A2 following the wall surface (slope) of the hole 83, and the corners of the flange portion 14d align with the vertices of the end 83a, eliminating the contact of the corners of the flange portion 14d with the wall surface of the hole 83. Thereafter, the tapered portion 14g comes into contact with the hole 81, and the ferrule 14 comes to a standstill. Specifically, the tapered portion 14g comes to rest within the hole 81 when a cross section perpendicular to the longitudinal direction X located between the front end and the rear end of the tapered portion 14g and having a diameter equal to the diameter D1 of the end 81a overlaps with the end 81a in the longitudinal direction X.

[0042] As described above, in the optical connector 1A according to this embodiment, the minimum diameter of the end 83b is longer than the longest diagonal line L of the flange portion 14d. Therefore, when the flange portion 14d passes through the end 83b, the flange portion 14d is smoothly inserted into the hole 83 without hitting the contour of the end 83b. In the optical connector 1A, the six contours S3 in the shape of the end 83b, which correspond to the sides S1 in the shape of the end 83a, bulge inward, and the diameter of the hole 83 continuously decreases from the end 83b to the end 83a. Therefore, as the flange portion 14d is further inserted, the flange portion 14d rotates along the slopes between the six contours S3 and the sides S1 on the front end side of the hole 83, and the corners of the flange portion 14d align with the vertices of the shape of the end 83a. Therefore, when manufacturing the optical connector 1A at a factory or the like, if the ferrule 14 of the completed optical connector 1A is pushed into the housing and rotated for adjustment, or if the ferrule 14 is pushed into the housing when cleaning the tip of an optical fiber with a cleaner, the corners of the flange portion 14d are prevented from getting caught on the end 83b of the hole 83 when the ferrule 14 is pulled out. As a result, the frequency of the ferrule 14 being pulled out is reduced. In the optical connector 1A, the cross section of the end 83b perpendicular to the longitudinal direction X is generally star-shaped, so that the six contours S3 corresponding to each side S1 at the end 83a can be realized in a simple shape, bulging inward. This improves the ease of processing the front housing 10A.

[0043] Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above embodiments and can be applied to various embodiments. For example, in the above embodiments, examples have been described in which the rear ends of the holes 82, 83 have a circular or approximately star-shaped shape, but the rear ends of the holes 82, 83 may have a shape other than a circular or approximately star-shaped shape as long as the six outlines S2, S3 corresponding to each side S1 at the front ends of the holes 82, 83 bulge outward or inward. [Explanation of symbols]

[0044] 1,1A...Optical connector 1a...front end 1b…Rear end 10, 10A, 11...Front housing 12, 13...Main body 12a,13a…Round hole 12b,13b…Protrusion 14,15...Ferrules 14a...tip 14b...Ferrule body 14c...Metal parts 14d...Flange 14e...Hollow tubular part 14f…Regular hexagonal column part 14g...Tapered part 14h...Elastic material 16,17...Opening 18, 19...Through holes 20...Inner housing 21...Front end 22...Tapered section 23...Rear end 24,25...Latch 26…Protrusion 30...Outer housing 30a…Top surface 30b…Bottom surface 31,32…Aperture 33...Housing body 34...Protruding part 35...Slit 36...Wall part 36a...part 37...Guide protrusion 40...Latch 40a...Proximal end 40b…Tip part 41, 42...Components 41a, 41b, 42a, 42b…Slope surface 41c, 42c...recess 43, 44...Engagement portion 50…tab 50a…front end 50b…rear end 51,52,53,54…protrusion 55,56...Slits 57...Gripping part 58...Protrusion 60...Boots 70...Elastic member 80...Cable holding member 81,82,83,84,85...hole 81a, 81b, 82a, 82b, 83a, 83b...edge 100...Adapter 141, 142...Through holes

Claims

1. an optical connector having a front end and a rear end opposite to the front end in a first direction, wherein an optical fiber can be inserted from the rear end, a ferrule capable of holding the optical fiber at the front end; a front housing that houses the ferrule, the ferrule has a flange portion having a regular hexagonal prism shape, the front housing has a through hole into which the flange portion is inserted, The through hole is a first hole portion having a cross section perpendicular to the first direction that is a continuous regular hexagon and that continuously reduces in diameter from the rear end side to the front end side, wherein the longest diagonal of the first regular hexagon, which is the cross section perpendicular to the first direction at the front end side, is shorter than the longest diagonal of the flange portion, the longest diagonal of the second regular hexagon, which is the cross section perpendicular to the first direction at the rear end side, is longer than the longest diagonal of the flange portion, and the distance between opposite sides of the second regular hexagon is shorter than the longest diagonal of the flange portion; a second hole portion located on a rear end side of the first hole portion in the first direction and continuing from the first hole portion; and a cross-sectional shape perpendicular to the first direction at a front end of the second hole portion is the same as a cross-sectional shape perpendicular to the first direction at a rear end of the first hole portion, In a cross section perpendicular to the first direction at the rear end of the second hole portion, six contours corresponding to the respective sides of the second regular hexagon bulge outward, and a minimum diameter of the rear end of the second hole portion is longer than a longest diagonal line of the flange portion, the second hole portion has a diameter that continuously decreases from the rear end toward the front end, the second hole portion has a contour line that extends linearly from a front end of the second hole portion to a rear end of the second hole portion when the second hole portion is cut along a cross section that includes a central axis of the second hole portion and is parallel to the central axis, an optical connector, wherein the contour line includes a first busbar extending from each vertex of the second regular hexagon and a second busbar extending from the midpoint of each side of the second regular hexagon, and the inclination angle of the first busbar with respect to the central axis is smaller than the inclination angle of the second busbar with respect to the central axis.

2. 2. The optical connector according to claim 1, wherein the second hole has a circular cross section perpendicular to the first direction at the rear end thereof.

3. an optical connector having a front end and a rear end opposite to the front end in a first direction, wherein an optical fiber can be inserted from the rear end, a ferrule capable of holding the optical fiber at the front end; a front housing that houses the ferrule, the ferrule has a flange portion having a regular hexagonal prism shape, the front housing has a through hole into which the flange portion is inserted, The through hole is a first hole portion having a cross section perpendicular to the first direction that is a continuous regular hexagon and that continuously reduces in diameter from the rear end side to the front end side, wherein the longest diagonal of the first regular hexagon, which is the cross section perpendicular to the first direction at the front end side, is shorter than the longest diagonal of the flange portion, the longest diagonal of the second regular hexagon, which is the cross section perpendicular to the first direction at the rear end side, is longer than the longest diagonal of the flange portion, and the distance between opposite sides of the second regular hexagon is shorter than the longest diagonal of the flange portion; a second hole portion located on a rear end side of the first hole portion in the first direction and continuing from the first hole portion; and a cross-sectional shape perpendicular to the first direction at a front end of the second hole portion is the same as a cross-sectional shape perpendicular to the first direction at a rear end of the first hole portion, In a cross section perpendicular to the first direction at the rear end of the second hole portion, six contours corresponding to the respective sides of the second regular hexagon bulge inward, and a minimum diameter of the rear end of the second hole portion is longer than a longest diagonal line of the flange portion, the second hole portion has a diameter that continuously decreases from the rear end toward the front end, the second hole portion has a contour line that extends linearly from a front end of the second hole portion to a rear end of the second hole portion when the second hole portion is cut along a cross section that includes a central axis of the second hole portion and is parallel to the central axis, an optical connector, wherein the contour line includes a first generatrix extending from each vertex of the second regular hexagon and a second generatrix extending from the midpoint of each side of the second regular hexagon, and wherein an inclination angle of the first generatrix with respect to the central axis is greater than an inclination angle of the second generatrix with respect to the central axis.

4. 4. The optical connector according to claim 3, wherein the cross section perpendicular to the first direction at the rear end of the second hole has a substantially star-shaped configuration.

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