Double-ended optical connector plug, optical fiber cable with optical connector, ferrule polishing method

Abstract

This invention enables simultaneous oblique polishing of two ferrules in a double-ended optical connector plug using a relatively simple structure. [Solution] One aspect of the present invention is a double-gang optical connector plug comprising: a first plug assembly housing a first ferrule having an insertion hole for a first optical fiber; a second connector plug assembly housing a second ferrule having an insertion hole for a second optical fiber; and a retaining member for holding the first connector plug assembly and the second plug assembly. In this double-gang optical connector plug, the relative axial positions of the first plug assembly and the second plug assembly can be changed to either a first position where the axial positions of the tips of the two ferrules coincide, or a second position where the axial positions of the tips of the two ferrules differ. The retaining member holds the first plug assembly and the second plug assembly in either the first or second position.

Description

Technical Field

[0001] The present invention relates to a duplex optical connector plug and a ferrule polishing method for obliquely polishing two ferrules provided on the duplex optical connector plug.

Background Art

[0002] Conventionally, in an optical connector plug, for the purpose of keeping the return loss extremely small, the end face of the ferrule is obliquely polished by a predetermined angle (for example, 8 degrees or 9 degrees). Oblique polishing means polishing the ferrule tip into an 8-degree or 9-degree convex spherical surface obliquely, and is also called APC (Angled Physical Contact) polishing. In the case of a duplex optical connector plug, when two ferrules are obliquely polished separately one by one, the time required for oblique polishing is long. Therefore, a method of polishing two ferrules simultaneously and a duplex optical connector plug therefor have been proposed (for example, Patent Documents 1 and 2).

[0003] Patent Document 1 describes a duplex optical connector plug configured such that when one of the first and second optical plug assemblies is rotated clockwise or counterclockwise about its axis, the rotational force of one of the first and second gears is transmitted to the other gear by an intermediate gear, causing the two optical plug assemblies to rotate clockwise or counterclockwise. Patent Document 1 also describes that after each optical plug assembly is rotated 90 degrees, two ferrules are polished simultaneously.

[0004] Patent Document 2 describes providing an axial slot in a connector body and a slide cam that engages with a ferrule through the slot, and during polishing, moving the slide cam axially by a polishing jig to axially displace the tip position of one ferrule of the duplex optical connector plug from the tip position of the other ferrule, and polishing the two ferrules simultaneously.

Prior Art Documents

[0005] [Patent Document 1] Patent No. 6173629 [Patent Document 2] U.S. Patent No. 11,448,833 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, conventional dual-gang optical connector plugs configured to polish two ferrules simultaneously have the problem of requiring a complex structure to enable simultaneous oblique polishing of both ferrules. For example, the dual-gang optical connector plug described in Patent Document 1 requires the incorporation of a complex gear mechanism to rotate each optical plug assembly. The dual-gang optical connector plug described in Patent Document 2 requires a complex mechanism to displace the ferrules from the outside using a slide cam.

[0007] This invention was made to solve the above-mentioned problems, and aims to achieve simultaneous oblique polishing of two ferrules in a double-ended optical connector plug with a relatively simple structure. [Means for solving the problem]

[0008] A first aspect of the present invention is a double-ended optical connector plug comprising: a first plug assembly that houses a first ferrule having an insertion hole for a first optical fiber formed therein, such that the tip of the first ferrule is exposed; a second plug assembly that houses a second ferrule having an insertion hole for a second optical fiber formed therein, such that the tip of the second ferrule is exposed; and a retaining member that holds the first plug assembly and the second plug assembly. In this double-ended optical connector plug, the relative axial positions of the first plug assembly and the second plug assembly can be changed to either a first position where the axial positions of the tips of the first ferrule and the tips of the second ferrule coincide, or a second position where the axial positions of the tips of the first ferrule and the tips of the second ferrule differ, and the retaining member holds the first plug assembly and the second plug assembly in the first or second position.

[0009] A second aspect of the present invention provides a dual optical connector plug, wherein, in the first aspect of the present invention, the first plug assembly has a first mating portion and the second plug assembly has a second mating portion. The first mating portion and the second mating portion can be mated in either the first or second position, and the holding member holds the first plug assembly and the second plug assembly in a state where the first mating portion and the second mating portion are mated in either the first or second position.

[0010] A third aspect of the present invention provides a dual optical connector plug, the same as the dual optical connector plug according to the first aspect, wherein the first plug assembly has a first mating portion and the second plug assembly has a second mating portion. This dual optical connector plug further comprises a casing member that houses at least a portion of each of the first plug assembly and the second plug assembly and has a third mating portion and a fourth mating portion. Each combination of the first mating portion and the third mating portion, and the second mating portion and the fourth mating portion, can be mated in either the first or second position, and the retaining member holds the casing member.

[0011] In the double-type optical connector plug according to the third embodiment described above, the casing member may have a pair of members configured to be reattachable.

[0012] In the double-type optical connector plug according to the third embodiment described above, the pair of members of the casing member may be of different colors.

[0013] In the double-type optical connector plug according to the third embodiment described above, the casing member may accommodate the first plug assembly and the second plug assembly when the positions of the first plug assembly and the second plug assembly are swapped, with each combination of the first mating portion and the fourth mating portion, and the second mating portion and the third mating portion, mated in either the first position or the second position.

[0014] In the double-type optical connector plug according to the third embodiment described above, the first plug assembly and the second plug assembly may have the same form.

[0015] In the double optical connector plug according to the third embodiment described above, the rear end of the first ferrule may protrude from the first plug assembly, and the rear end of the second ferrule may protrude from the second plug assembly.

[0016] A fourth aspect of the present invention is an optical fiber cable with an optical connector in which the first optical fiber and the second optical fiber are bonded and fixed to the double optical connector plug, wherein the ends of the first ferrule and the second ferrule are each beveled.

[0017] A fifth aspect of the present invention is a ferrule polishing method for obliquely polishing the first ferrule and the second ferrule of a double optical connector plug according to the second aspect. This ferrule polishing method includes the steps of: bonding and fixing the first optical fiber to the first ferrule and bonding and fixing the second optical fiber to the second ferrule; holding the first plug assembly and the second plug assembly in the holding member with the first mating portion and the second mating portion fitted together in the second position; simultaneously obliquely polishing the first ferrule and the second ferrule; and, after the oblique polishing step, holding the first plug assembly and the second plug assembly in the holding member with the first mating portion and the second mating portion fitted together in the first position.

[0018] A sixth aspect of the present invention is a ferrule polishing method for obliquely polishing the first ferrule and the second ferrule of a double optical connector plug according to the third aspect described above. This ferrule polishing method includes the steps of: bonding and fixing the first optical fiber to the first ferrule and bonding and fixing the second optical fiber to the second ferrule; fitting each combination of the first fitting portion and the third fitting portion, and the second fitting portion and the fourth fitting portion, at the second position to house at least a portion of each of the first plug assembly and the second plug assembly in the casing member and holding the casing member in the retaining member; simultaneously diagonally polishing the first ferrule and the second ferrule; and, after the diagonal polishing step, fitting each combination of the first fitting portion and the third fitting portion, and the second fitting portion and the fourth fitting portion, at the first position to house at least a portion of each of the first plug assembly and the second plug assembly in the casing member and holding the casing member in the retaining member.

[0019] A seventh aspect of the present invention is a ferrule polishing method for obliquely polishing a ferrule in a double optical connector plug. This double optical connector plug comprises a first plug assembly having a first mating portion and housing the first ferrule such that the tip of the first ferrule having an insertion hole for a first optical fiber is exposed; a second plug assembly having a second mating portion and housing the second ferrule such that the tip of the second ferrule having an insertion hole for a second optical fiber is exposed; a casing member having a third mating portion and a fourth mating portion and housing at least a portion of each of the first plug assembly and the second plug assembly; and a holding member for holding the casing member. Here, each combination of the first mating portion and the third mating portion, and the second mating portion and the fourth mating portion, are mated in a first position where the axial positions of the tip of the first ferrule and the tip of the second ferrule coincide. A ferrule polishing method according to the seventh embodiment includes the steps of: bonding and fixing the first optical fiber to the first ferrule and bonding and fixing the second optical fiber to the second ferrule; preparing a jig having a first jig fitting portion and a second jig fitting portion instead of the casing member; fitting the first fitting portion and the second fitting portion to the first jig fitting portion and the second jig fitting portion, respectively, so that at least a portion of each of the first plug assembly and the second plug assembly is housed in the jig such that the axial positions of the tip of the first ferrule and the tip of the second ferrule are different, and holding the jig in the holding member; simultaneously diagonally polishing the first ferrule and the second ferrule; and after the diagonal polishing step, housing at least a portion of each of the first plug assembly and the second plug assembly in the casing member instead of the jig, and holding the casing member in the holding member. [Effects of the Invention]

[0020] According to one aspect of the present invention, the time required for oblique polishing of the ferrule of a double optical connector plug can be reduced, while the structure of the double optical connector plug can be simplified.

Brief Description of the Drawings

[0021] [Figure 1] It is a perspective view of a two - piece optical connector plug according to the first embodiment. [Figure 2] It is a side view of a two - piece optical connector plug according to the first embodiment. [Figure 3] It is an exploded perspective view of a two - piece optical connector plug according to the first embodiment. [Figure 4] It is a sectional view taken along the line I - I of FIG. 2. [Figure 5] It is a view showing a method of inserting a ferrule into a plug frame. [Figure 6] It is a sectional view taken along the line II - II of FIG. 5. [Figure 7] It is a side view of the second stopper. [Figure 8] It is a plan view of the first stopper. [Figure 9] It is a sectional view taken along the line II - II of FIG. 7. [Figure 10] It is a perspective view of the first stopper and the second stopper. [Figure 11] It is a perspective view of the first stopper and the second stopper. [Figure 12] It is a plan view showing the first plug assembly and the second plug assembly when the first stopper and the second stopper are fitted in the normal position and the APC polishing position. [Figure 13] It is a perspective view of the housing. [Figure 14] It is a front view of the housing. [Figure 15] It is a side view of the housing. [Figure 16] It is a sectional view taken along the line IV - IV of FIG. 14. [Figure 17] It is a sectional view taken along the line V - V of FIG. 15. [Figure 18] It is a side view of the cylindrical member. [Figure 19] It is a view showing a temporary fixing method of the stoppers when the stoppers are fitted in the APC polishing position. [Figure 20]This is a cross-sectional view of the ferrule of a double optical connector plug according to the first embodiment during polishing. [Figure 21] This is a plan view showing the APC polishing position immediately after polishing of the double-type optical connector plug of the first embodiment. [Figure 22] This is a plan view of the double-type optical connector plug of the first embodiment, after APC polishing and set in the correct position. [Figure 23] This figure shows the assembly method for a double-type optical connector plug according to the first embodiment. [Figure 24] This is a perspective view of a double optical connector plug according to the second embodiment. [Figure 25] This is a side view of a double optical connector plug according to the second embodiment. [Figure 26] This is an exploded perspective view of a double optical connector plug according to the second embodiment. [Figure 27] This is a cross-sectional view taken from VI-VI in Figure 25. [Figure 28] This is a plan view of the stopper. [Figure 29] This is a side view of the plug assembly. [Figure 30] This is a cross-sectional view taken along line VII-VII in Figure 29. [Figure 31] This is a plan view of the casing section. [Figure 32] This is a perspective view showing the first casing section and the second casing section facing each other. [Figure 33] This is a plan view showing the first plug assembly and the second plug assembly fitted into the first casing at their normal and APC polished positions. [Figure 34] This is a perspective view showing the first plug assembly and the second plug assembly fitted into the first casing at their normal and APC polished positions. [Figure 35] This is a side view showing the plug assembly and casing member engaged. [Figure 36] This is a perspective view of the housing. [Figure 37] This is a front view of the housing. [Figure 38] This is a side view of the housing. [Figure 39] This is a cross-sectional view taken along line IX-IX in Figure 37. [Figure 40] This is a cross-sectional view of XX in Figure 38. [Figure 41] This is a cross-sectional view of the ferrule of a double optical connector plug of the second embodiment during polishing. [Figure 42] This is a plan view showing the APC polishing position immediately after polishing of the double-type optical connector plug of the second embodiment. [Figure 43] This is a plan view of the double-type optical connector plug of the second embodiment, after it has been set in the correct position after APC polishing. [Figure 44] This figure shows the assembly method for a double-type optical connector plug according to the second embodiment. [Figure 45] This is a plan view of the casing portion of a double optical connector plug according to the third embodiment. [Figure 46] This is an exploded perspective view showing a method for attaching a jig to a double-type optical connector plug according to the third embodiment. [Figure 47] This is a perspective view of the lower member of the jig. [Figure 48] This is a plan view of the lower component of the jig. [Figure 49] This is a perspective view of the upper component of the jig. [Figure 50] This is a bottom view of the upper component of the jig. [Figure 51] This is a plan view showing the first plug assembly and the second plug assembly before and after fitting them to the lower member of the jig. [Figure 52] This is a side view showing the jig attached to the first and second plug assemblies. [Figure 53] This is a cross-sectional view of the ferrule of a double optical connector plug of the third embodiment during polishing. [Figure 54] This is a plan view showing the APC polishing position immediately after polishing of the double-gang optical connector plug of the third embodiment. [Figure 55] This figure shows the assembly method for a double-type optical connector plug according to the third embodiment. [Modes for carrying out the invention]

[0022] The following describes several embodiments of the double-type optical connector plug (sometimes simply referred to as "optical connector plug") of the present invention. The double-type optical connector plug of each embodiment is used for optical connection between optical fibers by attaching it to an optical connector adapter (not shown). An optical fiber cable in which two optical fibers of an optical fiber cable are bonded and fixed to a double-type optical connector plug is called an optical fiber cable with an optical connector. In the following description, "axial direction" means the axial direction of the optical fiber, or the direction along the axial direction of the optical fiber, unless otherwise specified. In the drawings describing the parts constituting the double-type optical connector plug, the optical fibers are omitted as appropriate.

[0023] [First Embodiment] The double-type optical connector plug 1 of the first embodiment will be described below with reference to the drawings. Figures 1 to 4 show the overall shape of the double-gang optical connector plug 1. Figure 1 is a perspective view of the double-gang optical connector plug 1. Figure 2 is a side view of the double-gang optical connector plug 1. Figure 3 is an exploded perspective view of the double-gang optical connector plug 1. Figure 4 is a cross-sectional view of section II of Figure 2. In the following explanation, for the sake of clarity, we may define the forward / backward direction, up / down direction, and left / right direction as shown in Figure 3. The forward direction in Figure 3 corresponds to the forward direction in the axial direction.

[0024] The double-ended optical connector plug 1 is connected to the end of the optical fiber cable 100. As shown in Figure 4, the optical fiber cable 100 contains two optical fibers, a first optical fiber 101a and a second optical fiber 101b. In the following description, the first optical fiber 101a and the second optical fiber 101b will be referred to as "optical fiber 101" when referring to matters common to them.

[0025] The optical fiber 101 includes a core and a cladding around the core, and its structure allows light to propagate to the central core by having a higher refractive index in the core than in the cladding. Preferably, both the core and the cladding are made of quartz glass or plastic, which have high light transmittance. The optical fiber 101 is coated with a synthetic resin material and is called a strand or core. The material of the synthetic resin is not limited to a specific type, but examples include silicone resin, nylon resin, elastomer, UV-curing resin, etc. The optical fiber cable 100 includes a first optical fiber 101a and a second optical fiber 101b, as well as a tensile strength member 102 (see Figure 4). The tensile strength member 102 is provided to alleviate the tension generated in the optical fiber 101 when the optical fiber cable 100 is pulled or bent, thereby preventing damage to the optical fiber 101. The material of the tensile strength member 102 is not limited, but examples include aramid fibers such as Kevlar®, aramid fiber reinforced plastic (KFRP), glass fibers, glass fiber reinforced plastic (KFRP), polyethylene fibers, polyethylene fiber reinforced plastic, etc.

[0026] As shown in Figure 3, the dual optical connector plug 1 includes a first plug assembly 10a and a second plug assembly 10b, a housing 16, a cylindrical member 17, a crimping ring 18, and a boot 19. The first plug assembly 10a includes a first plug frame 11a, a first ferrule 21a, a first coil spring 22a, and a first stopper 15a. The second plug assembly 10b includes a second plug frame 11b, a second ferrule 21b, a second coil spring 22b, and a second stopper 15b. As will be described later, in the dual-type optical connector plug 1, the relative axial positions of the first plug assembly 10a and the second plug assembly 10b can be changed.

[0027] In this embodiment, the first plug frame 11a and the second plug frame 11b are identical in form, and in the following description, when referring to common aspects, they will be appropriately referred to as "plug frame 11". The first ferrule 21a and the second ferrule 21b are identical parts, and in the following description, when referring to common aspects, they will be appropriately referred to as "ferrule 21". The first coil spring 22a and the second coil spring 22b are identical parts, and in the following description, when referring to common aspects, they will be appropriately referred to as "coil spring 22". The first stopper 15a and the second stopper 15b are identical in form, and in the following description, they will be referred to as "stopper 15" as appropriate. Although the first stopper 15a and the second stopper 15b are identical in form, as shown in Figure 3, the first plug assembly 10a and the second plug assembly 10b are different in form because they engage with the first plug frame 11a and the second plug frame 11b in different orientations.

[0028] As shown in Figures 2 and 4, the first plug assembly 10a houses the first ferrule 21a such that the tip of the first ferrule 21a, which has an insertion hole for the first optical fiber 101a, is exposed. The second plug assembly 10b houses the second ferrule 21b such that the tip of the second ferrule 21b, which has an insertion hole for the second optical fiber 101b, is exposed.

[0029] The following describes in detail each component of the double-type optical connector plug 1. First, the ferrule 21 and plug frame 11 will be described with reference to Figures 5 and 6. Figure 5 shows the method of inserting the ferrule 21 into the plug frame 11. Figure 6 is a cross-sectional view of the plug frame 11 in Figure 5, taken along line II-II.

[0030] As shown in Figure 5, the ferrule 21 comprises, in order from the tip along the axial direction, a capillary 211 extending in the axial direction, a flange 212, a cylindrical sleeve 213, and a tube 214, and has a through hole (insertion hole) for inserting the optical fiber 101.

[0031] The capillary 211 holds the optical fiber 101. The capillary 211 is formed in a roughly cylindrical shape that is long in the axial direction, and has a tip surface at its axial end where the end face of the optical fiber 101 is exposed. A chamfered portion is formed on this tip surface. An optical fiber insertion hole (through hole) extending in the axial direction is drilled inside the capillary 211. The optical fiber 101 is inserted into the through hole of the capillary 211 with the coating removed from the strands or core. The capillary 211 is made from ceramic materials such as zirconia, plastic materials, crystallized glass, borosilicate glass, quartz, or other glass materials. Sleeve 213 is connected to the axial rear of capillary 211. A tube 214 (such as a PTFE tube) extending axially is connected to the axial rear of sleeve 213. A polygonal tubular flange 212, whose diameter is larger than that of capillary 211 and tube 214, is integrally formed at the front end of sleeve 213. Sleeve 213 and flange 212 are made from metal materials such as stainless steel, brass, or iron, or from synthetic resin materials. To secure the optical fiber 101 to the ferrule 21, adhesive is injected from the tube 214, the optical fiber 101 is then inserted through the tube 214, and fixed by heating. The adhesive is, for example, a thermosetting adhesive, preferably an epoxy adhesive or an acrylic adhesive.

[0032] As shown in Figures 3 and 4, the coil springs 22 (first coil spring 22a, second coil spring 22b) are positioned between the ferrule 21 and the stopper 15. The front end of the coil springs 22 abuts against the flange 212, and the rear end abuts against the spring contact surface 159 of the stopper 15 (see Figure 9). The coil springs 22 bias the ferrule 21 axially forward.

[0033] As shown in Figures 5 and 6, the plug frame 11 is made of, for example, a synthetic resin material and is formed in a hollow, roughly rectangular tubular shape. The release lever 115 extends from the front to the rear of the plug frame 11 and is formed to release the engagement between the double optical connector plug 1 and the optical connector adapter (not shown). The front end face 111 and rear end face 112 of the plug frame 11 have insertion openings for inserting the ferrule 21. A pair of openings 113 are formed to engage with the engaging projections 157 (see Figure 9) of the stopper 15. Inside the plug frame 11, a contact surface 114 is formed for contacting the tapered portion of the flange 212 of the ferrule 21. The contact surface 114 has the function of preventing the ferrule 21 from moving axially forward.

[0034] Next, the stopper 15 will be described with reference to Figures 7 to 11. The stopper 15 is made of, for example, a synthetic resin material. As mentioned above, the first stopper 15a and the second stopper 15b have the same form. Figure 7 is a right side view of the second stopper 15b. Figure 8 is a top view of the first stopper 15a. Figure 9 is a cross-sectional view taken along line III-III in Figure 7. Figure 10 is a perspective view of the first stopper 15a and the second stopper 15b from the front. Figure 11 is a perspective view of the first stopper 15a and the second stopper 15b from the rear.

[0035] As shown in Figures 7 and 8, the stopper 15 has a frame insertion portion 151 and an extension portion 152 formed behind the frame insertion portion 151. The frame insertion portion 151 is a hollow rectangular tube and has a pair of engaging protrusions 157 that protrude outward from the outer surface. As shown in Figure 9, a spring contact surface 159 is formed inside the frame insertion portion 151, against which the rear end of the coil spring 22 abuts. When the frame insertion portion 151 of the stopper 15 is inserted into the plug frame 11 from the rear end surface 112 (Figure 6) of the plug frame 11, a pair of engaging projections 157 engage with a pair of openings 113 of the plug frame 11. The first plug frame 11a and the first stopper 15a are connected with the first ferrule 21a and the first coil spring 22a housed inside. The second plug frame 11b and the second stopper 15b are connected with the second ferrule 21b and the second coil spring 22b housed inside.

[0036] The extension portion 152 is a part that extends rearward from the frame insertion portion 151. One side of the extension portion 152 is open overall, and a contact surface 1513 is formed on the outer edge of the open side. As shown in Figures 10 and 11, the first stopper 15a and the second stopper 15b are assembled with their contact surfaces 1513 facing each other. By bringing the contact surface 1513 of the first stopper 15a into contact with the contact surface 1513 of the second stopper 15b, a cavity H1 (see Figure 4) is formed through which the first optical fiber 101a and the second optical fiber 101b are inserted.

[0037] As shown in Figures 7 and 11, an arc-shaped groove 1512 for arranging a cylindrical member 17 (see Figure 3) is formed near the rear end surface 1511 of the extended portion 152. Therefore, when the first stopper 15a and the second stopper 15b are engaged, a circular groove is formed by the arc-shaped grooves 1512 of each stopper. Furthermore, a raised portion 158 with a circular arc cross-section is formed near the rear end surface 1511 of the extended portion 152. The raised portion 158 engages with the stopper engaging portion 163 (see Figure 16) of the housing 16, which will be described later, when the first stopper 15a and the second stopper 15b are engaged and the housing 16 is inserted into the housing 16 (Figure 3).

[0038] As shown in Figures 7 and 8, the stopper 15 has a concave tooth portion 153 that is recessed relative to the contact surface 1513 and a convex tooth portion 154 that protrudes relative to the contact surface 1513. As can be clearly seen in Figures 10 and 11, the concave tooth portion 153 consists of multiple concave teeth (five in the illustrated example), and the convex tooth portion 154 consists of one or more convex teeth (three in the illustrated example). Both the concave tooth portion 153 and the convex tooth portion 154 are formed along the axial direction. The concave teeth 153 and convex teeth 154 of the first stopper 15a are an example of the first fitting portion. The concave teeth 153 and convex teeth 154 of the second stopper 15b are an example of the second fitting portion.

[0039] The presence of concave teeth 153 and convex teeth 154 makes it possible to combine the first stopper 15a and the second stopper 15b at different positions in the axial direction. When the first stopper 15a and the second stopper 15b are combined in the normal position, the convex teeth 154 (3 convex teeth) of the first stopper 15a are engaged with the three central concave teeth of the five concave teeth of the concave teeth 153 of the second stopper 15b, and the convex teeth 154 (3 convex teeth) of the second stopper 15b are engaged with the three central concave teeth of the five concave teeth of the concave teeth 153 of the first stopper 15a. The "normal position" is the position where the axial positions of the tips of the two first ferrules 21a and second ferrules 21b of the double optical connector plug 1 coincide.

[0040] As will be described later, when the first ferrule 21a and the second ferrule 21b are ground at an angle, the axial positions of the tip of the first ferrule 21a and the tip of the second ferrule 21b are made different. For example, the convex teeth 154 (3 convex teeth) of the first stopper 15a are engaged with the three rear concave teeth of the five concave teeth of the second stopper 15b's concave teeth 153, and the convex teeth 154 (3 convex teeth) of the second stopper 15b are engaged with the three front concave teeth of the five concave teeth of the first stopper 15a's concave teeth 153. As a result, the first stopper 15a and the second stopper 15b are engaged with the second stopper 15b positioned axially forward by the length of one tooth compared to the first stopper 15a. In the normal position, the three convex teeth of the convex tooth portion 154 mesh with the three central concave teeth of the five concave teeth of the concave tooth portion 153. Therefore, it is not possible to engage the first stopper 15a and the second stopper 15b when they are shifted by two or more teeth from the normal position. The number of teeth included in each of the convex tooth portion 154 and the concave tooth portion 153 is not limited, but by ensuring that they mesh with at least two teeth, the accuracy of the connected state of the first stopper 15a and the second stopper 15b is ensured, and the overall bending strength is improved.

[0041] As shown in Figures 7 and 8, a protrusion 155 is formed that extends from the contact surface 1513 at a position forward of the convex tooth portion 154, and a groove 156 is formed in the contact surface 1513 at a position forward of the concave tooth portion 153. When the contact surfaces 1513 of the first stopper 15a and the second stopper 15b come into contact with each other, the protrusion 155 of the first stopper 15a fits into the groove 156 of the second stopper 15b, and the protrusion 155 of the second stopper 15b fits into the groove 156 of the first stopper 15a. This makes it difficult for relative vertical displacement between the first stopper 15a and the second stopper 15b to occur. The groove 156 is long in the axial direction so that the protrusion 155 can be received regardless of the fitting state of the concave teeth 153 and the convex teeth 154.

[0042] As described above, depending on the fitting state of the concave teeth 153 and the convex teeth 154, the first stopper 15a and the second stopper 15b can be positioned at the same axial position, or the axial position of one stopper can be made different from the axial position of the other stopper. Since the first stopper 15a and the second stopper 15b engage with the first plug frame 11a and the second plug frame 11b, respectively, depending on the fitting state of the concave teeth 153 and the convex teeth 154, the axial positions of the tip of the first ferrule 21a and the tip of the second ferrule 21b can be made to coincide, or the axial positions of the tip of the first ferrule 21a and the tip of the second ferrule 21b can be made to differ.

[0043] Figure 12 is a plan view of the first plug assembly 10a and the second plug assembly 10b in the normal position where the axial positions of the tips of the first ferrule 21a and the second ferrule 21b coincide (an example of the first position), and in the APC polishing position where the axial positions of the tips of the first ferrule 21a and the second ferrule 21b are different (an example of the second position).

[0044] By positioning the tip of either the first ferrule 21a or the second ferrule 21b axially forward of the other tip, the first ferrule 21a and the second ferrule 21b can be polished at an inclination with respect to the polishing reference surface (APC polishing). Although APC polishing is possible regardless of whether the first ferrule 21a or the second ferrule 21b is positioned forward, considering the connection between the connectors, it is necessary to standardize the orientation of the polished surface formed on the ferrules. Therefore, in the following description, the position of each part included in a double optical connector plug when the second ferrule 21b is positioned axially forward of the first ferrule 21a is referred to as the "APC polishing position".

[0045] In the APC polishing position shown in Figure 12, the convex teeth 154 (3 convex teeth) of the first stopper 15a engage with the three rear concave teeth of the five concave teeth of the second stopper 15b, and the convex teeth 154 (3 convex teeth) of the second stopper 15b engage with the three front concave teeth of the five concave teeth of the first stopper 15a, thereby positioning the second stopper 15b forward of the first stopper 15a. As a result, the second ferrule 21b housed in the second plug assembly 10b is positioned axially forward of the first ferrule 21a housed in the first plug assembly 10a. In Figure 12, the axial displacement of the two ferrules is denoted as SFT.

[0046] When performing APC polishing, the tips of the two ferrules are placed on the polishing reference surface PS (corresponding to the surface of the polishing film 78 described later). In Figure 12, the inclination angle of the central axis of the ferrules when the tips of the two ferrules are placed on the polishing reference surface PS is the polishing angle θ. Here, if the distance between the centers of the two ferrules is the pitch PT, the required displacement amount SFT can be expressed by the following equation (1) using the pitch PT and the polishing angle θ. SFT = PT / tan(90°-θ) ... (1) For example, in a double-gang LC type connector, the pitch PT can be 6.25 mm or 5.25 mm, and in APC polishing, the polishing angle θ can be set to 8 degrees or 9 degrees for each pitch PT value. The positional displacement SFT can be calculated by substituting the combination of pitch PT and polishing angle θ into equation (1), but the actual positional displacement SFT1 (design value) may be determined by correcting the calculated value as needed. In the engagement of the first stopper 15a and the second stopper 15b, the intertooth distance in the concave tooth portion 153 and the convex tooth portion 154 is determined such that when the occlusal position of the three convex teeth of the convex tooth portion 154 relative to the five concave teeth of the concave tooth portion 153 is shifted by the amount of one tooth, the axial displacement of the first stopper 15a and the second stopper 15b becomes the above positional displacement amount SFT1.

[0047] Next, the housing 16 will be described with reference to Figures 13 to 17. Figure 13 is a perspective view of the housing 16. Figure 14 is a front view of the housing 16. Figure 15 is a side view of the housing 16. Figure 16 is a cross-sectional view taken along line IV-IV of Figure 14. Figure 17 is a cross-sectional view taken along line VV of Figure 15.

[0048] The housing 16 is an example of a retaining member that holds the first plug assembly 10a and the second plug assembly 10b. The housing 16 is made of, for example, a synthetic resin material and has a housing body 161 and a release arm 162 formed on the upper surface of the housing body 161. The housing body 161 holds and accommodates at least a portion of the first stopper 15a and the second stopper 15b. The release arm 162 extends from the rear to the front of the housing body 161 and, when operated downward, pushes down the release levers 115 (Figure 5) of the first plug frame 11a and the second plug frame 11b, thereby releasing the engagement between the double optical connector plug 1 and the optical connector adapter (not shown).

[0049] The housing body 161 has a roughly rectangular parallelepiped shape with openings at its front and rear ends, and can accommodate the pair of extensions 152 of the first stopper 15a and the second stopper 15b when they are combined together. As shown in Figure 17, the rear portion 1612 of the housing body 161 is shaped to match the outer edge shape of the pair of extension portions 152 of the first stopper 15a and the second stopper 15b. As shown in Figure 16, a stopper engagement portion 163 is formed at the rear end of the rear portion 1612. The stopper engagement portion 163 is the part that engages with the pair of raised portions 158 (see Figure 11) formed at the rear ends of the pair of extension portions 152, and has a larger diameter than the other parts of the rear portion 1612. The first stopper 15a and the second stopper 15b are engaged with the housing 16 by the engagement of the pair of raised portions 158 with the stopper engagement portion 163.

[0050] When the first stopper 15a and the second stopper 15b are inserted from the front end of the housing body 161, the portion of the housing body 1612 that contacts the pair of raised portions 158 of the first stopper 15a and the second stopper 15b is formed to be slightly smaller than the pair of raised portions 158. Therefore, before the pair of raised portions 158 of the first stopper 15a and the second stopper 15b reach the stopper engagement portion 163, the housing body 161 is slightly deformed outward, and the first stopper 15a and the second stopper 15b can be temporarily fixed to the housing body 161. When the pair of raised portions 158 reach the stopper engagement portion 163, the deformation of the housing body 161 is released, and the pair of raised portions 158 engage with the stopper engagement portion 163. Furthermore, by moving the first stopper 15a and the second stopper 15b forward along the axial direction, the housing body 161 deforms slightly, releasing the engagement between the pair of protrusions 158 and the stopper engagement portion 163, and allowing the first stopper 15a and the second stopper 15b to be removed from the front end of the housing body 161. The housing 16 can be used to temporarily fasten the first plug assembly 10a and the second plug assembly 10b in either the normal position or the APC polishing position shown in Figure 12.

[0051] Next, the cylindrical member 17, the crimping ring 18, and the boot 19 will be described. The cylindrical member 17 is connected to the first stopper 15a and the second stopper 15b, and is a member for fixing the optical fiber cable 100 to the double optical connector plug 1. Figure 18 shows a side view of the cylindrical member 17.

[0052] As shown in Figure 18, the cylindrical member 17 has an annular projection 171 formed at the front and a cylindrical crimped portion 172 formed at the rear. The annular projection 171 of the cylindrical member 17 is positioned in a circular groove (a combination of the arc grooves 1512 of each stopper) formed when the first stopper 15a and the second stopper 15b are combined. The crimped portion 172 of the cylindrical member 17 and the crimped portion 181 of the crimping ring 18 are crimped together with the tensile strength member 102 (see Figure 4) included in the optical fiber cable 100 sandwiched in between. As shown in Figure 3, the crimping ring 18 has a crimped portion 181 provided at the front and a tube 182 extending rearward from the crimped portion 181. The crimped portion 181 is cylindrical, and its inner diameter is slightly larger than the outer diameter of the crimped portion 172. Therefore, the crimped portion 172 of the cylindrical member 17 can be inserted into the crimped portion 181. The tube 182 is a heat-shrinkable tube, which shrinks when heated and adheres tightly to the outer circumference of the optical fiber cable 100. The boot 19 is provided to prevent excessive bending of the optical fiber cable 100.

[0053] Next, APC polishing of the first ferrule 21a and second ferrule 21b of the double optical connector plug 1 will be described with reference to Figures 19 to 21. Figure 19 is a plan view showing the first plug assembly 10a and the second plug assembly 10b in the state before and after being temporarily fixed to the housing 16. Figure 20 is a cross-sectional view of the double optical connector plug 1 of this embodiment when the ferrules are polished. Figure 21 is a plan view of the double optical connector plug 1 showing the APC polishing position immediately after APC polishing.

[0054] As explained with reference to Figure 12, when performing APC polishing on the first ferrule 21a and the second ferrule 21b, the engagement position of the first stopper 15a and the second stopper 15b is adjusted so that the second ferrule 21b, which is housed in the second plug assembly 10b, is positioned axially forward of the first ferrule 21a, which is housed in the first plug assembly 10a (the state in Figure 19 where it is "not temporarily fixed to the housing"). When the double optical connector plug 1 is in the normal position, the first stopper 15a and the second stopper 15b are removed from the housing 16, and the combination of the first stopper 15a and the second stopper 15b is temporarily released. The meshing positions of the concave teeth 153 and convex teeth 154 of each stopper are changed, and then the contact surfaces 1513 of the first stopper 15a and the second stopper 15b are brought into contact with each other (see, for example, Figure 10) to change to the APC polishing position. Note that in the APC polishing position, the second stopper 15b is positioned axially forward of the first stopper 15a, so the cylindrical member 17 cannot be placed inside each stopper.

[0055] As shown in Figure 19, after combining the first plug assembly 10a and the second plug assembly 10b at the APC polishing position, the first stopper 15a and the second stopper 15b at the APC polishing position are temporarily fixed to the housing 16. The first stopper 15a and the second stopper 15b are in axially offset positions, and the axial positions of the raised portion 158 (Figure 10) of each stopper are also offset, so the first stopper 15a and the second stopper 15b cannot be engaged by the housing 16. However, the first stopper 15a and the second stopper 15b are temporarily fixed to the housing body 161 with the housing body 161 inserted to a position forward of the stopper engagement portion 163 in the axial direction of the housing body 161.

[0056] As shown in Figure 20, APC polishing is performed on the double-gang optical connector plug 1, in which the first plug assembly 10a and the second plug assembly 10b, assembled at the APC polishing position, are temporarily fixed to the housing 16. Figure 20 shows a cross-section of only the polishing holder 74, polishing pad 77, polishing film 78, and the turntable 79 of the polishing machine (not shown) in which the double-gang optical connector plug 1 is set in the polishing holder 74.

[0057] The polishing holder 74 temporarily holds the first plug assembly 10a and the second plug assembly 10b of the double optical connector plug 1 so that both the first ferrule 21a and the second ferrule 21b can contact the polishing film 78. That is, the polishing holder 74 temporarily holds the first plug assembly 10a and the second plug assembly 10b inclined at a predetermined polishing angle (e.g., 8 or 9 degrees). The polishing holder 74 is designed according to a predetermined axial displacement SFT1 of the first ferrule 21a and the second ferrule 21b. After the polishing holder 74 holds the dual optical connector plug 1, the polishing holder 74 is placed in the polishing machine. When the polishing holder 74 is placed in the polishing machine, as shown in Figure 20, the tip of the capillary 211 of the first ferrule 21a contacts the polishing film 78 attached to the polishing pad 77 at an angle, and the tip of the capillary 211 of the second ferrule 21b also contacts the polishing film 78 at an angle. After the polishing holder 74 is placed in the polishing machine, when the polishing machine is started, the turntable 79 of the polishing machine starts to rotate and revolve, and the tips of the capillaries 211 of the first ferrule 21a and the second ferrule 21b are polished at an angle by the polishing film 78 attached to the polishing pad 77. That is, the first ferrule 21a and the second ferrule 21b are polished simultaneously. Figure 21 shows the dual optical connector plug 1 immediately after being removed from the polishing holder 74. As shown in Figure 21, the first ferrule 21a and the second ferrule 21b are beveled. After polishing is complete, the first plug assembly 10a and the second plug assembly 10b are assembled in their normal positions as shown in Figure 22 and engaged with the housing 16.

[0058] Next, the assembly method of the double-type optical connector plug 1 of this embodiment will be described with reference to Figure 23. This assembly method includes a ferrule polishing method according to one embodiment. Figure 23 shows the assembly method of the double-type optical connector plug 1 in step order.

[0059] Referring to Figure 23, in step S2, the boot 19, crimping ring 18, cylindrical member 17, and housing 16 are first passed through the optical fiber cable 100 from the cable end. Furthermore, the first optical fiber 101a and the second optical fiber 101b, which are covered with strands or cores, are exposed from the cable end of the optical fiber cable 100. The first stopper 15a and the first coil spring 22a are passed through the first optical fiber 101a, and the second stopper 15b and the second coil spring 22b are passed through the second optical fiber 101b. Next, in step S4, the first optical fiber 101a and the second optical fiber 101b are exposed from their strands or cores. The length of the exposed optical fiber is not limited, but is in the range of 5 mm to 15 mm. In steps S6 and S8, the first optical fiber 101a and the second optical fiber 101b, exposed from the strands or cores, are bonded and fixed to the first ferrule 21a and the second ferrule 21b, respectively. Specifically, first, a thermosetting adhesive is injected from the tube 214 (Figure 5) towards the through-hole of the capillary 211 (Figure 5) using a dispenser (syringe) (step S6). The first optical fiber 101a and the second optical fiber 101b, exposed from the strands or cores, are inserted from the tube 214 and passed through the through-hole of the capillary 211. Furthermore, the adhesive inside the first ferrule 21a and the second ferrule 21b is cured by heating them (step S8).

[0060] In step S10, the first plug assembly 10a and the second plug assembly 10b are assembled. Specifically, the first plug frame 11a and the first stopper 15a are engaged so as to accommodate the first ferrule 21a and the first coil spring 22a, and the second plug frame 11b and the second stopper 15b are engaged so as to accommodate the second ferrule 21b and the second coil spring 22b. Each ferrule is biased by a coil spring inside the corresponding plug assembly, with its tip exposed from the plug frame.

[0061] In step S12, the final assembly is performed. Specifically, the annular protrusion 171 (Figure 18), which is the tip of the cylindrical member 17, is placed on the first stopper 15a and the second stopper 15b, and then the first stopper 15a and the second stopper 15b are combined in their correct positions and engaged with the housing 16. Next, the crimped portion 172 of the cylindrical member 17 and the crimped portion 181 (Figure 3) of the crimping ring 18 are crimped together with the tensile strength member 102 contained in the optical fiber cable 100 sandwiched between them. Furthermore, the tube 182 of the crimping ring 18 is heated and thermally shrunk to make it tightly adhere to the optical fiber cable 100, and the boot 19 is slid to the rear ends of the first stopper 15a and the second stopper 15b. After the final assembly is complete, if necessary, the first ferrule 21a and the second ferrule 21b may be subjected to PC (Physical Contact) polishing and core eccentricity adjustment to further reduce connection loss. Core eccentricity adjustment is performed by pushing each ferrule backward and rotating it around its axis to change the contact position of the flange 212 (Figure 5).

[0062] In step S14, the first stopper 15a and the second stopper 15b are removed from the housing 16 for later APC polishing, and the combination of the first stopper 15a and the second stopper 15b is released. Then, the first stopper 15a and the second stopper 15b are combined at the APC polishing position and temporarily fixed to the housing 16 (see Figure 19). In step S16, as shown in Figure 20, the double optical connector plug 1, which has been changed to the APC polishing position, is attached to the polishing holder 74. Then, the polishing holder 74 is placed in the polishing machine, and APC polishing is performed on the first ferrule 21a and the second ferrule 21b. As a result, the first ferrule 21a and the second ferrule 21b are polished at an angle, as shown in Figure 21. After the APC polishing is completed, in step S18, the first stopper 15a and the second stopper 15b are removed from the housing 16 and released. Then, the first stopper 15a and the second stopper 15b are combined in their normal positions and engaged with the housing 16. As a result, a double-ended optical connector plug 1 is obtained in which the first ferrule 21a and the second ferrule 21b are obliquely polished, as shown in Figure 22.

[0063] The above describes the dual-type optical connector plug 1. In the example described above, depending on the mating state of the concave teeth 153 and convex teeth 154 of the first stopper 15a and the second stopper 15b, either the first plug assembly 10a or the second plug assembly 10b can be positioned axially forward. Therefore, as shown in Figure 12, at the APC polishing position, although the second plug assembly 10b should be positioned axially forward of the first plug assembly 10a, it is possible to mistakenly assemble the first plug assembly 10a so that it is positioned axially forward of the second plug assembly 10b (misassembly). However, even if misassembly occurs, the double-type optical connector plug 1 cannot be set in the polishing holder 74 (Figure 20) when the first plug assembly 10a is positioned axially forward of the second plug assembly 10b, so the misassembly can be detected before performing APC polishing. Furthermore, to prevent incorrect assembly (i.e., to prevent the first stopper 15a from being positioned axially forward of the second stopper 15b), the first stopper 15a and the second stopper 15b can be made into different forms.

[0064] [Second Embodiment] The following describes the double-type optical connector plug 2 of the second embodiment with reference to the drawings. Figures 24 to 27 show the overall shape of the double-gang optical connector plug 2. Figure 24 is a perspective view of the double-gang optical connector plug 2. Figure 25 is a side view of the double-gang optical connector plug 2. Figure 26 is an exploded perspective view of the double-gang optical connector plug 2. Figure 27 is a cross-sectional view of Figure 25, taken along line VI-VI. In the following explanation, for the sake of clarity, we may define the forward / backward direction, up / down direction, and left / right direction as shown in Figure 26. The forward direction in Figure 26 corresponds to the forward direction in the axial direction.

[0065] The double-ended optical connector plug 2 is connected to the end of the optical fiber cable 100, as previously described. As shown in Figure 26, the double-type optical connector plug 2 includes a first plug assembly 30a and a second plug assembly 30b, a casing member 13, a housing 32, a cylindrical member 17, a crimping ring 18, and a boot 19. The first plug assembly 30a includes a first plug frame 11a, a first ferrule 21a, a first coil spring 22a, and a first stopper 31a. The second plug assembly 30b includes a second plug frame 11b, a second ferrule 21b, a second coil spring 22b, and a second stopper 31b. The casing member 13 has a first casing portion 14a and a second casing portion 14b. In this embodiment, the first casing portion 14a and the second casing portion 14b are identical in form, and in the following description, when referring to common aspects, they will be appropriately referred to as "casing portion 14". As will be described later, in the dual-type optical connector plug 2, the relative axial positions of the first plug assembly 30a and the second plug assembly 30b can be changed.

[0066] In the dual-type optical connector plug 2, the first plug frame 11a and the second plug frame 11b, the first ferrule 21a and the second ferrule 21b, the first coil spring 22a and the second coil spring 22b, the cylindrical member 17, the crimping ring 18, and the boot 19 are common parts with the dual-type optical connector plug 1, and therefore will not be described again below.

[0067] The first stopper 31a and the second stopper 31b are identical in form, and in the following description, when referring to common aspects, they will be referred to as "stopper 31" as appropriate. In the double-gang optical connector plug 2, unlike the double-gang optical connector plug 1, the first plug assembly 30a, which includes the first stopper 31a, and the second plug assembly 30b, which includes the second stopper 31b, are identical in form. In the following description, when referring to aspects common to the first plug assembly 30a and the second plug assembly 30b, they will be referred to as "plug assembly 30" as appropriate.

[0068] The following will provide a detailed explanation focusing on the unique components of the double-type optical connector plug 2. First, the plug assembly 30 will be described with reference to Figures 28 to 30. Figure 28 is a plan view of the stopper 31. Figure 29 is a side view of the plug assembly 30. Figure 30 is a cross-sectional view taken along line VII-VII of Figure 29.

[0069] The stopper 31 is made of, for example, a synthetic resin material and is molded into a hollow, roughly rectangular tube shape. As shown in Figure 28, it has a frame insertion portion 311 and a casing engagement portion 312 which is formed with a step between it and the frame insertion portion 311. The frame insertion portion 311 is the part that engages with the plug frame 11, and the casing engagement portion 312 is the part that engages with the casing member 13. The frame insertion portion 311 has a pair of engaging protrusions 315 that project outward from the outer surface. These pair of engaging protrusions 315 engage with a pair of openings 113 (see Figure 5) of the plug frame 11. The plug frame 11 and the stopper 31 are connected with the ferrule 21 and coil spring 22 housed inside. As shown in Figure 30, a spring contact surface 316 is formed inside the stopper 31, against which the rear end of the coil spring 22 abuts. The tapered portion of the flange 212 (Figure 5) of the ferrule 21 abuts against the contact surface 114 of the plug frame 11, preventing axial forward movement. The front end of the coil spring 22 abuts against the flange 212, and its rear end abuts against the spring contact surface 316 of the stopper 31, biasing the ferrule 21 axially forward.

[0070] Since the stopper 31 of this embodiment has a shorter axial length than the stopper 15 of the first embodiment, the ferrule 21 (more specifically, the tube 214) protrudes from the rear end of the stopper 31, as shown in Figure 29.

[0071] As shown in Figures 28 and 29, the stopper 31 has fitting portions 313 formed on both sides of the casing engagement portion 312. The fitting portions 313 engage with the fitting portions 142a and 142b (Figure 31) of the casing portion 14, which will be described later. The fitting portion 313 consists of multiple pairs of protrusions (three pairs in the illustrated example). The fitting portion 313 of the first stopper 31a is an example of the first fitting portion. The fitting portion 313 of the second stopper 31b is an example of the second fitting portion.

[0072] Next, the casing member 13 will be described with reference to Figures 31 and 32. Figure 31 is a plan view of the casing portion 14 (first casing portion 14a, second casing portion 14b). Figure 32 is a perspective view of the first casing portion 14a and the second casing portion 14b facing each other.

[0073] As described above, the casing member 13 has a first casing portion 14a and a second casing portion 14b of the same form as a pair of members configured to be re-engaged. As shown in Figure 26, the first casing portion 14a and the second casing portion 14b engage with the first stopper 31a and the second stopper 31b by sandwiching the respective casing engagement portions 312 of the first stopper 31a and the second stopper 31b from above and below. As shown in Figure 32, the first casing portion 14a and the second casing portion 14b are fitted together facing each other to form a cavity H2 (see Figure 27) through which the first optical fiber 101a and the second optical fiber 101b are inserted, and the first optical fiber 101a and the second optical fiber 101b are branched to the first plug assembly 30a and the second plug assembly 30b, respectively (see Figure 27).

[0074] Ribs 1412 and 1413 of different heights are formed at the front end of the casing portion 14. When the first casing portion 14a and the second casing portion 14b are fitted together, the rib 1412 of the first casing portion 14a faces the rib 1413 of the second casing portion 14b, and the rib 1413 of the first casing portion 14a faces the rib 1412 of the second casing portion 14b.

[0075] Assembly engagement portions 141a and 141b are arranged side by side in the front portion of the casing portion 14. Assembly engagement portion 141a engages with the first plug assembly 30a (specifically, the casing engagement portion 312 of the first stopper 31a), and assembly engagement portion 141b engages with the second plug assembly 30b (specifically, the casing engagement portion 312 of the second stopper 31b).

[0076] The casing portion 14 has engaging projections 144, 146, and 1410, and engaging recesses 145, 147, and 1411. When the first casing portion 14a and the second casing portion 14b are fitted together, the engaging projection 144 engages with the engaging recess 145, the engaging projection 146 engages with the engaging recess 147, and the engaging projection 1410 engages with the engaging recess 1411. As will be described later, when switching between the normal position and the APC polishing position, it is necessary to release the engagement between the first casing portion 14a and the second casing portion 14b, so these engaging projections and recesses are configured to be easily released.

[0077] As shown in Figures 31 and 32, an arc-shaped groove 149 for arranging a cylindrical member 17 (see Figure 18) is formed near the rear end face of the casing portion 14. Therefore, when the first casing portion 14a and the second casing portion 14b are fitted together, a circular groove is formed by the arc-shaped groove 149 of each casing portion. Furthermore, as shown in Figure 32, a raised portion 148 with a circular arc cross-section is formed near the rear end surface of the casing portion 14. The raised portion 148 engages with the casing engagement portion 323 of the housing 32 (see Figure 39), which will be described later, when the first casing portion 14a and the second casing portion 14b are fitted together and inserted into the housing 32 (Figure 26).

[0078] The assembly engagement portions 141a and 141b have a substantially U-shaped cross-section and are formed to accommodate the casing engagement portions 312 of the first stopper 31a and the second stopper 31b, respectively, when the first casing portion 14a and the second casing portion 14b are fitted together. The assembly engagement portions 141a and 141b have fitting portions 142a and 142b that fit with the fitting portions 313 of the first stopper 31a and the second stopper 31b. The fitting portion 142a of the first casing portion 14a and the fitting portion 142b of the second casing portion 14b fit with the fitting portion 313 of the first stopper 31a and are an example of a third fitting portion. The fitting portion 142b of the first casing portion 14a and the fitting portion 142a of the second casing portion 14b engage with the fitting portion 313 of the second stopper 31b, and this is an example of a fourth fitting portion. Each of the fitting portions 142a and 142b consists of multiple pairs of recesses (four pairs in the illustrated example). These multiple pairs of recesses are formed at predetermined intervals along the axial direction. This predetermined interval is the same as the interval at which multiple pairs of protrusions are formed in the casing engagement portion 312 of the stopper 31.

[0079] A fitting portion 313 consisting of multiple pairs of protrusions is formed on the stopper 31, and fitting portions 142a and 142b are formed on the first casing portion 14a and the second casing portion 14b, respectively, making it possible to engage the first plug assembly 30a and the second plug assembly 30b at different positions in the axial direction. This point will be explained with reference to Figures 33 and 34. Figure 33 is a plan view showing the first plug assembly 30a and the second plug assembly 30b fitted into the first casing portion 14a in their normal and APC polished positions. Figure 34 is a perspective view showing the first plug assembly 30a and the second plug assembly 30b fitted into the first casing portion 14a in their normal and APC polished positions.

[0080] When the first plug assembly 30a and the second plug assembly 30b are engaged in the normal position (the "normal position" in Figures 33 and 34), the three pairs of protrusions of the fitting portion 313 of the first stopper 31a are fitted with the three rear pairs of recesses of the four pairs of recesses of the fitting portion 142a of the casing portion 14, and the three pairs of protrusions of the fitting portion 313 of the second stopper 31b are fitted with the three rear pairs of recesses of the four pairs of recesses of the fitting portion 142b of the casing portion 14. In this case, the axial positions of the tips of the first ferrule 21a and the second ferrule 21b are the same. Alternatively, the three pairs of protrusions on the fitting portion 313 of the first stopper 31a may be fitted with the three front pairs of recesses out of the four pairs of recesses on the fitting portion 142a of the casing portion 14, and the three pairs of protrusions on the fitting portion 313 of the second stopper 31b may be fitted with the three front pairs of recesses out of the four pairs of recesses on the fitting portion 142b of the casing portion 14. In this case as well, the axial positions of the tips of the first ferrule 21a and the second ferrule 21b will be the same.

[0081] As described later, when APC polishing is performed on the first ferrule 21a and the second ferrule 21b ("APC polishing position" in Figures 33 and 34), the axial positions of the tips of the first ferrule 21a and the second ferrule 21b are made different. Specifically, the three pairs of protrusions of the fitting portion 313 of the first stopper 31a are fitted with the three rear pairs of recesses of the four pairs of recesses of the fitting portion 142a of the casing portion 14, and the three pairs of protrusions of the fitting portion 313 of the second stopper 31b are fitted with the three front pairs of recesses of the four pairs of recesses of the fitting portion 142b of the casing portion 14. In this case, the second plug assembly 30b is positioned axially forward of the first plug assembly 30a by a predetermined distance between one recess. It is also possible to move the second plug assembly 30b further axially forward so that it is positioned axially forward by a predetermined distance between the two recesses compared to the first plug assembly 30a. However, the amount of misalignment between the assemblies is large, making it impossible to set the double-type optical connector plug 2 in the polishing holder 74.

[0082] Similar to the first embodiment, when performing APC polishing, the tips of the two ferrules are placed on the polishing reference surface PS. In Figure 33, based on the polishing angle θ and the pitch PT between the two ferrules, the SFT can be calculated from equation (1) above to determine the axial displacement of the two ferrules. The actual displacement SFT1 (design value) is determined by correcting the calculated value as necessary. In the engagement between the stopper 31 and the casing portion 14, the axial distance between a pair of adjacent protrusions of the fitting portion 313 of the stopper 31 and the axial distance between a pair of adjacent recesses of the fitting portions 142a and 142b of the casing portion 14 are set to be the same and to coincide with the positional displacement amount SFT1.

[0083] As shown in Figures 33 and 34, the first plug assembly 30a and the second plug assembly 30b are fitted into the first casing portion 14a in their normal or APC polished positions, and the cylindrical member 17 is placed in the first casing portion 14a. Then, the second casing portion 14b is fitted onto the first casing portion 14a from above, thereby connecting the first plug assembly 30a and the second plug assembly 30b, the casing member 13, and the cylindrical member 17. Figure 35 is a side view showing the first plug assembly 30a and the second plug assembly 30b engaged with the casing member 13 together with the cylindrical member 17 in their normal positions. The casing member 13, engaged with the first plug assembly 30a and the second plug assembly 30b, is engaged with and fitted into the housing 32.

[0084] Next, the housing 32 will be described with reference to Figures 36 to 40. Figure 36 is a perspective view of the housing 32. Figure 37 is a front view of the housing 32. Figure 38 is a side view of the housing 32. Figure 39 is a cross-sectional view taken along line IX-IX of Figure 37. Figure 40 is a cross-sectional view taken along line XX of Figure 38.

[0085] The housing 32 is an example of a retaining member that holds the first plug assembly 30a and the second plug assembly 30b by holding the casing member 13. The housing 32 is made of, for example, a synthetic resin material and has a housing body 321 and a release arm 322 formed on the upper surface of the housing body 321. The housing body 321 holds and accommodates at least a portion of the casing member 13. The release arm 322 extends forward from the rear end of the housing body 321 and, when operated downward, pushes down the release levers 115 (Figure 5) of the first plug frame 11a and the second plug frame 11b, thereby releasing the engagement between the double optical connector plug 2 and the optical connector adapter (not shown).

[0086] The housing body 321 has a roughly rectangular parallelepiped shape with openings at its front and rear ends, and is capable of receiving the casing member 13. As shown in Figure 40, the rear portion 3212 of the housing body 321 has a shape that corresponds to the outer edge shape of the casing member 13. As shown in Figure 39, a casing engagement portion 323 is formed at the rear end of the rear portion 3212. The casing engagement portion 323 is the part that engages with a pair of raised portions 148 (see Figure 32) formed at the rear end of the casing member 13, and has a larger diameter than the rest of the rear portion 3212. The casing member 13 is fitted into the housing 16 by the engagement of the pair of raised portions 148 with the casing engagement portion 323.

[0087] When inserting the casing member 13 from the front end of the housing body 321, the portion of the housing body 3212 that contacts the pair of raised portions 148 of the casing member 13 is formed to be slightly smaller than the pair of raised portions 148. Therefore, before the pair of raised portions 148 of the casing member 13 reach the casing engagement portion 323, the housing body 321 is slightly deformed outward, and the casing member 13 is held in place by the housing body 321. When the pair of raised portions 148 reach the casing engagement portion 323, the deformation of the housing body 321 is released, and the pair of raised portions 148 engage with the casing engagement portion 323. Furthermore, by moving the casing member 13 forward along the axial direction, the housing body 321 deforms slightly, releasing the engagement between the pair of raised portions 148 and the casing engagement portion 323, and the casing member 13 can be removed from the front end of the housing body 321. In the double-type optical connector plug 2 of the second embodiment, the first casing portion 14a and the second casing portion 14b of the casing member 13 can be fitted together regardless of the mating position of the first plug assembly 30a and the second plug assembly 30b with the casing member 13. Therefore, the casing member 13 engaged with each assembly can be fitted into the housing 32 at either the normal position or the APC polishing position.

[0088] As described above, the cylindrical member 17, crimping ring 18, and boot 19 in this embodiment can be the same as those in the first embodiment, so they will not be described in detail here.

[0089] APC polishing of the first ferrule 21a and second ferrule 21b of the double-type optical connector plug 2 is performed by designating the first plug assembly 30a and the second plug assembly 30b as the APC polishing locations. When the double optical connector plug 2 is in the correct position, the casing member 13 is removed from the housing 32, the engagement of the first casing portion 14a and the second casing portion 14b of the casing member 13 is released, and the first plug assembly 30a and the second plug assembly 30b are engaged with the first casing portion 14a in the APC polishing position. That is, the engagement positions of the fitting portions 313 of the stoppers of the first plug assembly 30a and the second plug assembly 30b and the fitting portions 142a and 142b of the first casing portion 14a are changed, then the second casing portion 14b is placed over the first casing portion 14a, and the casing member 13 is engaged with the housing 32 again.

[0090] Figure 41 shows a cross-sectional view of the ferrule of a double-ended optical connector plug 2 during polishing. As shown in Figure 41, APC polishing is performed on the double-gang optical connector plug 2, with the first plug assembly 30a and the second plug assembly 30b, which have been changed to the APC polishing position, held in the housing 32. Figure 41 shows a cross-section of only the polishing holder 74 and the polishing machine when the double-gang optical connector plug 2 is set in the polishing holder 74. The polishing holder 74 and the polishing machine may be the same as those described in the first embodiment with reference to Figure 20. Figure 42 shows a double optical connector plug 2 indicating the APC polishing position immediately after APC polishing. As shown in Figure 42, the first ferrule 21a and the second ferrule 21b are polished at an angle. Figure 43 is a plan view of the double-type optical connector plug 2 after APC polishing and when it has been set in its correct position. After polishing is complete, the first plug assembly 30a and the second plug assembly 30b are assembled in their correct positions as shown in Figure 43.

[0091] Next, the assembly method of the double-type optical connector plug 2 of this embodiment will be described with reference to Figure 44. This assembly method includes a ferrule polishing method according to one embodiment. Figure 44 shows the assembly method of the double-type optical connector plug 2 in step order.

[0092] Referring to Figure 44, in step S1, the first plug assembly 30a and the second plug assembly 30b are assembled. Specifically, the first plug frame 11a and the first stopper 31a are engaged so that the first ferrule 21a and the first coil spring 22a are housed, and the second plug frame 11b and the second stopper 31b are engaged so that the second ferrule 21b and the second coil spring 22b are housed. Each ferrule is biased by a coil spring inside the corresponding plug assembly, with its tip exposed from the plug frame. Next, in step S2a, the boot 19, crimp ring 18, housing 32, and cylindrical member 17 are passed through the optical fiber cable 100 from the cable end. Furthermore, the first optical fiber 101a and the second optical fiber 101b, which are covered with strands or cores, are exposed from the cable end of the optical fiber cable 100. Next, in step S4, the first optical fiber 101a and the second optical fiber 101b are exposed from their strands or cores. The length of the exposed optical fiber is not limited, but is in the range of 5 mm to 15 mm. In steps S6 and S8, the first optical fiber 101a and the second optical fiber 101b, exposed from the strands or cores, are bonded and fixed to the first ferrule 21a and the second ferrule 21b, respectively. Specifically, first, a thermosetting adhesive is injected from the tube 214 (Figure 5) towards the through-hole of the capillary 211 (Figure 5) using a dispenser (syringe) (step S6). The first optical fiber 101a and the second optical fiber 101b, exposed from the strands or cores, are inserted from the tube 214 and passed through the through-hole of the capillary 211. Furthermore, the adhesive inside the first ferrule 21a and the second ferrule 21b is cured by heating them (step S8).

[0093] In step S12a, the final assembly is performed. Specifically, the annular projection 171 (Figure 18), which is the tip of the cylindrical member 17, is placed on the first casing portion 14a of the casing member 13. Then, the first plug assembly 30a and the second plug assembly 30b are engaged with the first casing portion 14a in their correct positions, the second casing portion 14b is placed over the first casing portion 14a, and the casing member 13 (first casing portion 14a, second casing portion 14b) is connected to the housing 32. Next, the crimped portion 172 of the cylindrical member 17 and the crimped portion 181 (Figure 3) of the crimping ring 18 are crimped together with the tensile strength member 102 contained in the optical fiber cable 100 sandwiched between them. After the final assembly is complete, the first ferrule 21a and the second ferrule 21b may be subjected to PC polishing and core eccentricity adjustment as needed to further reduce connection loss. Core eccentricity adjustment is performed by changing the contact position of the flange 212 (Figure 5) by pushing each ferrule backward and rotating it around its axis.

[0094] In step S14a, the casing member 13 is removed from the housing 32 for subsequent APC polishing, the engagement between the first casing portion 14a and the second casing portion 14b of the casing member 13 is released, the first plug assembly 30a and the second plug assembly 30b are engaged with the first casing portion 14a at the APC polishing position, the second casing portion 14b is placed over the first casing portion 14a, and the casing member 13 is fitted back into the housing 32. In step S16, as shown in Figure 41, the double optical connector plug 2, which has been changed to the APC polishing position, is held in the polishing holder 74, and then the polishing holder 74 is installed in the polishing machine to perform APC polishing on the first ferrule 21a and the second ferrule 21b. As a result, the first ferrule 21a and the second ferrule 21b are polished at an angle, as shown in Figure 42. After the APC polishing is completed, in step S18a, the casing member 13 is removed from the housing 32 and the engagement between the first casing portion 14a and the second casing portion 14b of the casing member 13 is released. The first plug assembly 30a and the second plug assembly 30b are engaged with the first casing portion 14a in their proper positions, then the second casing portion 14b is placed over the first casing portion 14a, and the casing member 13 is fitted back into the housing 32. Furthermore, the tube 182 of the crimping ring 18 is heated and thermally shrunk to make it tightly adhere to the optical fiber cable 100, and the boot 19 is slid to the rear end of the casing member 13. As a result, a double-ended optical connector plug 2 with the first ferrule 21a and the second ferrule 21b being obliquely polished is obtained, as shown in Figure 43.

[0095] The above describes the dual-type optical connector plug 2. In this embodiment, the case in which the first plug assembly 30a and the second plug assembly 30b have the same form has been described, but this is not limited to this case. If necessary, the first stopper 31a and the second stopper 31b can be made into different forms, to the extent that it does not interfere with the connection with the first plug frame 11a, the second plug frame 11b, and the casing member 13. In the illustrated example of this embodiment, the number of pairs of protrusions included in the fitting portion 313 (Figure 28) provided on the stopper 31 is 3, but this is not limited to this. As long as the fitting portion 313 of the stopper 31 can be fitted to the casing portion 14 at different axial positions, the number of pairs of protrusions included in the fitting portion 313, and the number of pairs of recesses included in each of the fitting portions 142a and 142b that fit with the fitting portion 313 can be set as appropriate. Furthermore, although the illustrated example shows a case where multiple pairs of protrusions are formed as the fitting portion 313 of the stopper 31 and multiple pairs of recesses are formed as the fitting portions 142a and 142b of the casing portion 14, this is not limited to this configuration. Conversely, multiple pairs of recesses may be formed as the fitting portion 313 of the stopper 31 and multiple pairs of protrusions may be formed as the fitting portions 142a and 142b of the casing portion 14.

[0096] In the example described above, depending on the mating state of the mating portions 313 of the first stopper 31a and the second stopper 31b and the mating portions 142a and 142b of the first casing portion 14a, either the first plug assembly 30a or the second plug assembly 30b can be positioned axially forward. Therefore, as shown in Figure 33, in APC polishing, although the second plug assembly 30b should be positioned axially forward of the first plug assembly 30a, it is possible to mistakenly assemble the first plug assembly 30a so that it is positioned axially forward of the second plug assembly 30b (misassembly). However, even if misassembly occurs, the double-type optical connector plug 2 cannot be set in the polishing holder 74 (Figure 41) when the first plug assembly 30a is positioned axially forward of the second plug assembly 30b, so the misassembly can be detected before performing APC polishing.

[0097] In the double-type optical connector plug 2 of this embodiment, the total length of the stopper 31 is shorter than the total length of the stopper 15 of the first embodiment, which has the advantage of making the overall assembly work easier. In the case of the double-ended optical connector plug 1 of the first embodiment, the total length of the stopper 15 is relatively long, so when engaged with the plug frame 11, the rear end of the ferrule 21 does not protrude from the stopper 15. Therefore, before assembling the first plug assembly 10a and the second plug assembly 10b, it is necessary to pass the optical fiber 101 through the stopper 15 and the coil spring 22 and perform the bonding work of the optical fiber 101 to the ferrule 21. However, since the rear end of the ferrule 21 does not protrude from the stopper 15, the adhesive injection work becomes a difficult task. In contrast, in the double-type optical connector plug 2 of this embodiment, the overall length of the stopper 31 is relatively short, and the ferrules 21 protrude from the rear ends of the first plug assembly 30a and the second plug assembly 30b, respectively. Therefore, as shown in Figure 44, the first plug assembly 30a and the second plug assembly 30b can be assembled first, and then the optical fiber 101 can be bonded to the ferrule 21, improving work efficiency. Although the above advantages cannot be obtained, in the case of a double-ended optical connector plug 2, it is not necessary to have the ferrule 21 (tube) protrude from the rear end of the plug assembly 30.

[0098] As mentioned above, in the dual-type optical connector plug 2, the first plug assembly 30a and the second plug assembly 30b have the same form. Therefore, polarity conversion is possible by swapping the positions of the first plug assembly 30a and the second plug assembly 30b, thereby swapping the positions of the first optical fiber 101a and the second optical fiber 101b. Specifically, the engagement between the first casing portion 14a and the second casing portion 14b is released, a part of the second plug assembly 30b (second stopper 31b) is accommodated in the assembly engagement portion 141a of the first casing portion 14a, and after accommodating a part of the first plug assembly 30a (first stopper 31a) in the assembly engagement portion 141b of the first casing portion 14a, the second casing portion 14b is placed over the first casing portion 14a. As a result, the fitting portion 142a of the first casing portion 14a and the fitting portion 142b of the second casing portion 14b engage with the fitting portion 313 of the second stopper 31b, and the fitting portion 142b of the first casing portion 14a and the fitting portion 142a of the second casing portion 14b engage with the fitting portion 313 (second fitting portion) of the first stopper 31a.

[0099] In one embodiment, the first casing portion 14a and the second casing portion 14b constituting the casing member 13 are of different colors. This makes it possible to determine from the appearance whether or not the polarity of the double optical connector plug 2 has been reversed. For example, when performing polarity conversion, the operation involves not only changing the positions of the first plug assembly 30a and the second plug assembly 30b, but also swapping the upper and lower positions of the first casing portion 14a and the second casing portion 14b. In this case, if the first casing portion 14a and the second casing portion 14b are colored differently, as shown in Figure 35, it is possible to determine which of the first casing portion 14a and the second casing portion 14b is on top or bottom from the colors of the ribs 1412 and ribs 1413 of the first casing portion 14a and the second casing portion 14b, and thereby determine whether the polarity conversion has not been performed or has been performed. As shown in Figure 25, the ribs 1412 and ribs 1413 are exposed even when the casing member 13 is engaged with the housing 32, so there is no problem in making the determination even after the housing 32 has been engaged. Although not shown in the diagram, a portion of the rear end surfaces of the first casing portion 14a and the second casing portion 14b are also exposed, so it is possible to determine which of the first casing portion 14a and the second casing portion 14b is on top or bottom even when viewed from the rear.

[0100] [Third Embodiment] The following describes a third embodiment of a double-type optical connector plug with reference to the drawings. As described in each of the embodiments above, after APC polishing is performed on the first ferrule 21a and the second ferrule 21b, it is necessary to reliably return them from the APC polishing position to the normal position. In the double-gang optical connector plug 1 of the first embodiment, as shown in Figure 19, the APC polishing position is such that the second stopper 15b is shifted axially forward compared to the first stopper 15a. Therefore, the cylindrical member 17 cannot be placed inside each stopper, and the first stopper 15a and the second stopper 15b cannot be engaged with the housing 16. For this reason, the possibility of forgetting to return the APC polishing position to the normal position after APC polishing is very low. On the other hand, in the double-gang optical connector plug 2 of the second embodiment, the casing member 13 engaged with each assembly can be engaged with the housing 32 at either the normal position or the APC polishing position. Therefore, there is a possibility of forgetting to return the APC polishing position to the normal position after APC polishing. In a double-gang optical connector plug that has not been returned to the normal position from the APC polishing position, connector connection will be hindered. Therefore, the double-type optical connector plug of the third embodiment is configured to prevent forgetting to return the APC polishing position to the correct position.

[0101] The dual optical connector plug of this embodiment differs from the dual optical connector plug 2 of the second embodiment only in that it has a pair of casing parts that make up the casing member 13. Figure 45 shows a plan view of the casing part 14A of the dual optical connector plug of this embodiment. In the second embodiment, the assembly engagement portions 141a and 141b have fitting portions 142a and 142b consisting of four pairs of recesses (see Figure 31), whereas the assembly engagement portions 141a and 141b of the casing portion 14A differ in that, as shown in Figure 45, they have fitting portions 142Aa and 142Ab consisting of three pairs of recesses. Therefore, the first plug assembly 30a and the second plug assembly 30b (see Figures 29 and 30), each having a fitting portion 313 consisting of three pairs of protrusions, are always in the correct position when fitted with the fitting portions 142Aa and 142Ab.

[0102] In the dual optical connector plug of this embodiment, when performing APC polishing on the first ferrule 21a and the second ferrule 21b, the first plug assembly 30a and the second plug assembly 30b are mounted on a jig 5 (described later) instead of the casing member 13. After the APC polishing is completed, the first plug assembly 30a and the second plug assembly 30b are re-engaged with the casing member 13 instead of the jig. With this method, the possibility of the operator forgetting to remove the jig and return the casing member 13 to its original state after polishing is very low.

[0103] The jig 5 will be described below with reference to Figures 46 to 50. Figure 46 is an exploded perspective view showing how to attach the jig 5 to the double optical connector plug of this embodiment. Figure 47 is a perspective view of the lower member 51 of the jig 5. Figure 48 is a plan view of the lower member 51 of the jig 5. Figure 49 is a perspective view of the upper member 52 of the jig 5. Figure 50 is a bottom view of the upper member 52 of the jig 5. Figures 49 and 50 show the back side of the upper member 52 (the side facing the lower member 51). As shown in Figure 46, the jig 5 is made of, for example, a synthetic resin material and has a lower member 51 and an upper member 52 that fit together. When performing APC polishing on the first ferrule 21a and the second ferrule 21b, instead of the casing member 13, the first plug assembly 30a and the second plug assembly 30b and the cylindrical member 17 are sandwiched from above and below by the lower member 51 and the upper member 52. In the following explanation, for the sake of clarity, we may define the forward / backward direction, up / down direction, and left / right direction as shown in Figure 46. The forward direction in Figure 46 corresponds to the forward direction in the axial direction.

[0104] As shown in Figures 47 to 50, the front end of the lower member 51 has front end surfaces 5110a and 5110b. Front end surface 5110b is provided to protrude forward more than front end surface 5110a. The front end of the upper member 52 has front end surfaces 5210a and 5210b. Front end surface 5210b is provided to protrude forward more than front end surface 5210a. The lower member 51 has an extended portion 5112 that extends to the rear. The upper member 52 has an extended portion 5212 that extends to the rear. The extended portions 5112 and 5212 are provided to prevent damage to the jig 5 during APC polishing.

[0105] Assembly engagement portions 511a and 511b are arranged side by side on the front portion of the lower member 51. Assembly engagement portions 521a and 521b are arranged side by side on the front portion of the upper member 52. When the lower member 51 and the upper member 52 are fitted together, the assembly engagement portions 511a and 521a engage with the first plug assembly 30a (specifically, the casing engagement portion 312 of the first stopper 31a (Figure 28)), and the assembly engagement portions 511b and 521b engage with the second plug assembly 30b (specifically, the casing engagement portion 312 of the second stopper 31b).

[0106] The lower member 51 has engaging protrusions 514, 516, 518 and engaging recesses 515, 517, 519. The upper member 52 has engaging protrusions 524, 526, 528 and engaging recesses 525, 527, 529. When the lower member 51 and the upper member 52 are fitted together, the contact surface 513 of the lower member 51 and the contact surface 523 of the upper member 52 come into contact, and the engaging projection 514 and the engaging recess 525 engage, the engaging projection 516 and the engaging recess 527 engage, the engaging projection 518 and the engaging recess 529 engage, the engaging recess 515 and the engaging projection 524 engage, the engaging recess 517 and the engaging projection 526 engage, and the engaging recess 519 and the engaging projection 528 engage. The engagements by these engaging projections and recesses are configured to be easily released.

[0107] An arc groove 510 is formed near the rear end surface of the lower member 51. An arc groove 520 is formed near the rear end surface of the upper member 52. The arc grooves 510 and 520 form circular grooves for positioning the cylindrical member 17 (see Figure 18) when the lower member 51 and the upper member 52 are fitted together. The external shape of the jig 5 when the lower member 51 and the upper member 52 are fitted together is close to the external shape of the casing member 13, except for the extended parts 5112 and 5212, and is shaped so that the jig 5 is held in the housing 32 when inserted into the housing 32.

[0108] As shown in Figures 47 and 48, the assembly engagement portions 511a and 511b of the lower member 51 are substantially U-shaped in cross-section and are formed to accommodate the casing engagement portions 312 (Figure 28) of the first stopper 31a and the second stopper 31b, respectively, when the lower member 51 and the upper member 52 are fitted together. The assembly engagement portions 511a and 511b are formed with jig fitting portions 512a and 512b that fit with the fitting portions 313 of the first stopper 31a and the second stopper 31b, respectively. Jig fitting portion 512a is an example of the first jig fitting portion, and jig fitting portion 512b is an example of the second jig fitting portion. Each of the jig fitting portions 512a and 512b consists of a pair of axially elongated recesses that accommodate multiple pairs of protrusions of the fitting portions 313 of the first stopper 31a and the second stopper 31b. As shown in Figure 48, the axial lengths of the protrusions constituting the jig fitting portions 512a and 512b are the same. The assembly engagement portion 511b and the jig fitting portion 512b are positioned axially forward of the assembly engagement portion 511a and the jig fitting portion 512a.

[0109] The stopper 31 has a fitting portion 313 consisting of multiple pairs of protrusions, and the lower member 51 has jig fitting portions 512a and 512b, which makes it possible to engage the first plug assembly 30a and the second plug assembly 30b at different positions in the axial direction. This point will be explained with reference to Figure 51. Figure 51 is a plan view showing the first plug assembly 30a and the second plug assembly 30b before and after fitting them to the lower member 51 of the jig 5. As described above, the jig fitting portion 512b is positioned axially forward of the jig fitting portion 512a, and this axial displacement is SFT1. Therefore, when the first plug assembly 30a is housed in the assembly engagement portion 511a of the lower member 51 and the second plug assembly 30b is housed in the assembly engagement portion 511b of the lower member 51, as shown in Figure 51, the APC polishing position of the second plug assembly 30b is located axially forward of the first plug assembly 30a by a displacement of SFT1.

[0110] When performing APC polishing, the first plug assembly 30a and the second plug assembly 30b are fitted onto the lower member 51 of the jig 5, the cylindrical member 17 is placed on the lower member 51, and the upper member 52 is fitted onto the lower member 51. Furthermore, the jig 5 is inserted into the housing 32 and held in place. Figure 52 is a side view showing the jig 5 attached to the first plug assembly 30a and the second plug assembly 30b. Note that the housing 32 is not shown in Figure 52 in order to show the state of the lower member 51 and the upper member 52.

[0111] Figure 53 shows a cross-sectional view of the ferrule of the double optical connector plug of this embodiment during polishing. APC polishing is performed on the double-gang optical connector plug, with the first plug assembly 30a and the second plug assembly 30b mounted on the jig 5 and held in the housing 32, as shown in Figure 53. Figure 53 shows a cross-section of only the polishing holder 74, polishing pad 77, polishing film 78, and the polishing machine's turntable 79, with the double-gang optical connector plug set in the polishing holder 74. The polishing holder 74 and the polishing machine may be the same as those described in the first embodiment with reference to Figure 20. As shown in Figure 53, the extended portions 5112 and 5212 of the jig 5 prevent damage to the jig 5 when inserting or removing the double-type optical connector plug from the polishing holder 74. This is particularly effective when the jig 5 is molded from a low-strength resin. Figure 54 shows a double optical connector plug indicating the APC polishing position immediately after APC polishing. As shown in Figure 54, the first ferrule 21a and the second ferrule 21b are polished at an angle. After polishing is complete, the casing member 13 is attached to the first plug assembly 30a and the second plug assembly 30b in place of the jig 5. The appearance of the double optical connector plug after the casing member 13 is attached is the same as that shown in Figure 43.

[0112] Next, the assembly method of the double-type optical connector plug of this embodiment will be described with reference to Figure 55. This assembly method includes a ferrule polishing method according to one embodiment. Figure 55 shows the assembly method of the double-type optical connector plug of this embodiment in step order. Note that steps S1 to S12a in Figure 55 are the same as in the second embodiment (Figure 44), so a redundant explanation will be omitted.

[0113] As shown in Figure 45, the casing portion 14A of the casing member 13 in this embodiment has fitting portions 142Aa and 142Ab, each consisting of three pairs of recesses. Therefore, in the final assembly of step S12a, the first plug assembly 30a and the second plug assembly 30b are fitted to the casing portion 14A in their correct positions. In step S14b, the casing member 13 is removed from the housing 32 for subsequent APC polishing, and the jig 5 is attached to the first plug assembly 30a and the second plug assembly 30b in place of the casing member 13. By attaching the jig 5 to the first plug assembly 30a and the second plug assembly 30b, the first plug assembly 30a and the second plug assembly 30b are positioned for APC polishing, as shown in Figure 51. Next, the housing 32 is slid axially to hold the jig 5. In step S16, as shown in Figure 53, the double optical connector plug, which has been changed to the APC polishing position, is held in the polishing holder 74, and then the polishing holder 74 is installed in the polishing machine to perform APC polishing on the first ferrule 21a and the second ferrule 21b. As a result, the first ferrule 21a and the second ferrule 21b are polished at an angle, as shown in Figure 54. After the APC polishing is completed, in step S18b, the jig 5 is removed from the housing 32, the lower member 51 and upper member 52 of the jig 5 are released from their engagement, the first plug assembly 30a and the second plug assembly 30b are re-engaged with the casing member 13, and the casing member 13 is inserted into the housing 32 and fitted. Furthermore, the tube 182 of the crimping ring 18 is heated and thermally shrunk to make it tightly adhere to the optical fiber cable 100, and the boot 19 is slid to the rear end of the casing member 13.

[0114] In the above assembly method (ferrule polishing method), when performing APC polishing on a double-type optical connector plug that is always in the correct position, a special jig (the above jig 5) is used to change the first plug assembly 30a and the second plug assembly 30b to the APC polishing position. Since it is necessary to reassemble the jig 5 and the casing member after APC polishing, the problem of forgetting to return them to the correct position does not occur.

[0115] The above describes multiple embodiments of the double-type optical connector plug and the assembly method of the double-type optical connector plug, including the ferrule polishing method, according to the present invention. In the double-type optical connector plug 1 of the first embodiment, the first plug assembly 10a and the second plug assembly 10b are each equipped with a first stopper 15a and a second stopper 15b that can be mated at different positions in the axial direction, so that the relative positions of the first plug assembly 10a and the second plug assembly 10b can be changed depending on the mating position of the stoppers. The first plug assembly 10a and the second plug assembly 10b are held by the housing 16 in a predetermined position, either the normal position or the APC polished position.

[0116] In the double-type optical connector plug 2 of the second embodiment, the relative positions of the first plug assembly 30a and the second plug assembly 30b can be changed depending on the mating position between the stopper 31, which is included in the first plug assembly 30a and the second plug assembly 30b, which have a common configuration, and the casing portion 14. The first plug assembly 30a and the second plug assembly 30b are held by the housing 32 in a predetermined position, either the normal position or the APC polished position. In both the double-type optical connector plugs 1 and 2, a mating portion can be formed on the stopper or casing member, making it possible to change the relative position of the two plug assemblies with a relatively simple structure. Furthermore, since it is easy to switch the relative position of the two plug assemblies between the normal position and the APC polished position, polishing time can be reduced by performing APSC polishing on the two ferrules simultaneously.

[0117] In the third embodiment of the dual optical connector plug, the first plug assembly 30a and the second plug assembly 30b are held in their normal positions by the housing 32, while the dual optical connector plug 2 of the second embodiment is used as a base. For the dual optical connector plug of the third embodiment, the casing member 13 can be changed to the APC polishing position by switching to the jig 5, and APC polishing can be performed. The jig 5 is configured to be in the APC polishing position when the first plug assembly 30a and the second plug assembly 30b are mounted. Since the jig 5 is always used during APC polishing, for example, the first plug assembly 30a and the second plug assembly 30b will not be shipped in the APC polishing position.

[0118] The present invention is not limited to the embodiments and assembly methods described above. Furthermore, the embodiments and assembly methods described above can be improved or modified in various ways without departing from the spirit of the present invention. For example, the embodiments and assembly methods described above can be applied to various connectors such as LC type, SC type, and MU type. Moreover, they are not limited to these and can be applied to optical connectors having similar structures. [Explanation of symbols]

[0119] 1, 2... Double-type optical connector plug 10a…First plug assembly 11a…First plug frame 111...Front end surface 112…Rear end surface 113...Aperture 114…Abutment surface 115... Disengagement lever 21a...First ferrule 211... Capillary 212…Flange 213... Sleeves 214... Tube 22a...First coil spring 15a...First stopper 151... Frame insertion section 152...Extension part 153... Concave tooth portion 154...Convex tooth portion 155... protruding part 156...Groove 157…Engagement protrusion 158...Protuberance 159... Spring contact surface 1510…Front end surface 1511…Rear end surface 1512... Circular groove 1513…Abutment surface 10b...Second plug assembly 11b...Second plug frame 21b...Second ferrule 22b... Second coil spring 15b... Second stopper 13…Casing component 14a...First casing section 14b...Second casing section 141a, 141b… Assembly engagement parts 142a, 142b… recessed 144,146,1410…Engagement protrusion 145, 147, 1411… Engagement recess 148...Protuberance 149... Circular groove 1412, 1413… Ribs 16… Housing 161... Housing body 162... Disengagement arm 163... Stopper engagement part 17…Cylindrical member 171... Ring-shaped protrusion 172...Cylindrical member 18… Crimping ring 181... Crimped portion 182... Tube 19... Boots 30a…First plug assembly 30b...Second plug assembly 31a...First stopper 31b... Second stopper 311... Frame insertion section 312...Casing engagement part 313... protruding part 315…Engagement protrusion 316... Spring contact surface 32… Housing 321... Housing body 322... Disengagement arm 323...Casing engagement part 5... Jig 51...Lower member 511a, 511b… Assembly engagement parts 512a, 512b...Jig fitting part 513…Abutment surface 514,516,518…Engagement protrusion 515, 517, 519… Engaging recesses 510... Circular groove 5110a, 5110b…Front end surface 5112...Extension part 52…Upper member 521a, 521b… Assembly engagement part 523…Abutment surface 524,526,528…Engagement protrusion 525, 527, 529… Engagement recesses 520... Circular groove 5210a, 5210b…Front end surface 5212...Extension section 74… Polishing holder 77... Polishing pad 78… Polishing film 79... Turntable 100… Fiber optic cable 101a...First optical fiber 101b...Second optical fiber 102…Tensile strength body H1,H2…Cavity

Claims

1. A first plug assembly that houses the first ferrule such that the tip of the first ferrule, in which an insertion hole for the first optical fiber is formed, is exposed, A second plug assembly that houses the second ferrule such that the tip of the second ferrule, in which an insertion hole for the second optical fiber is formed, is exposed, The device comprises a retaining member that holds the first plug assembly and the second plug assembly, The relative axial positions of the first plug assembly and the second plug assembly can be changed to either a first position where the axial positions of the tips of the first ferrule and the tips of the second ferrule coincide, or a second position where the axial positions of the tips of the first ferrule and the tips of the second ferrule differ. The retaining member holds the first plug assembly and the second plug assembly in the first or second position. A double-prong optical connector plug.

2. The first plug assembly has a first mating portion, The second plug assembly has a second mating portion, The first fitting portion and the second fitting portion can be fitted together in either the first position or the second position. The retaining member holds the first plug assembly and the second plug assembly in a state where the first fitting portion and the second fitting portion are fitted together in either the first or second position. A double-type optical connector plug as described in claim 1.

3. The first plug assembly has a first mating portion, The second plug assembly has a second mating portion, The aforementioned double-type optical connector plug further comprises a casing member that houses at least a portion of each of the first plug assembly and the second plug assembly, and has a third mating portion and a fourth mating portion. Each combination of the first fitting portion and the third fitting portion, and the second fitting portion and the fourth fitting portion, can be fitted in either the first position or the second position. The retaining member holds the casing member. A double-type optical connector plug as described in claim 1.

4. The casing member has a pair of members configured to be reattachable, A double-type optical connector plug as described in claim 3.

5. The pair of members of the casing member are each of different colors. A double-type optical connector plug as described in claim 4.

6. The casing member is capable of accommodating the first plug assembly and the second plug assembly when the positions of the first plug assembly and the second plug assembly are swapped, with each combination of the first fitting portion and the fourth fitting portion, and the second fitting portion and the third fitting portion, fitted in either the first position or the second position. A double-type optical connector plug as described in claim 3.

7. The first plug assembly and the second plug assembly have the same form. A double optical connector plug as described in any one of claims 3 to 6.

8. The rear end of the first ferrule protrudes from the first plug assembly, and the rear end of the second ferrule protrudes from the second plug assembly. A double optical connector plug as described in any one of claims 3 to 6.

9. An optical fiber cable with an optical connector, wherein the first optical fiber and the second optical fiber are bonded and fixed to a double optical connector plug as described in any one of claims 1 to 6, The tips of the first ferrule and the second ferrule are beveled. Fiber optic cable with optical connector.

10. A ferrule polishing method for obliquely polishing the first ferrule and the second ferrule of a double optical connector plug as described in claim 2, The process involves bonding and fixing the first optical fiber to the first ferrule, and bonding and fixing the second optical fiber to the second ferrule, With the first fitting portion and the second fitting portion fitted together in the second position, the first plug assembly and the second plug assembly are held by the retaining member; A step of simultaneously obliquely polishing the first ferrule and the second ferrule, After the diagonal polishing step, the first plug assembly and the second plug assembly are held by the retaining member with the first fitting portion and the second fitting portion fitted together in the first position, A ferrule polishing method including the following.

11. A ferrule polishing method for obliquely polishing the first ferrule and the second ferrule of a double optical connector plug as described in claim 3, The process involves bonding and fixing the first optical fiber to the first ferrule, and bonding and fixing the second optical fiber to the second ferrule, The steps include fitting the combinations of the first fitting portion and the third fitting portion, and the second fitting portion and the fourth fitting portion, at the second position to house at least a portion of the first plug assembly and the second plug assembly in the casing member, and holding the casing member in the retaining member, A step of simultaneously obliquely polishing the first ferrule and the second ferrule, After the diagonal polishing step, the steps include fitting the first fitting portion and the third fitting portion, and the second fitting portion and the fourth fitting portion, into the first position, housing at least a portion of each of the first plug assembly and the second plug assembly in the casing member, and holding the casing member in the retaining member, A ferrule polishing method including the following.

12. A ferrule polishing method for diagonally polishing a ferrule in a double-ended optical connector plug, The aforementioned double-type optical connector plug is A first plug assembly having a first mating portion houses the first ferrule such that the tip of the first ferrule, which has an insertion hole for the first optical fiber formed therein, is exposed, A second plug assembly having a second mating portion houses the second ferrule such that the tip of the second ferrule, which has an insertion hole for the second optical fiber formed therein, is exposed, A casing member having a third fitting portion and a fourth fitting portion, which houses at least a portion of each of the first plug assembly and the second plug assembly, The system comprises a retaining member for holding the casing member, Each combination of the first fitting portion and the third fitting portion, and the second fitting portion and the fourth fitting portion, is fitted at a first position where the axial positions of the tip of the first ferrule and the tip of the second ferrule coincide. The ferrule polishing method described above is The process involves bonding and fixing the first optical fiber to the first ferrule, and bonding and fixing the second optical fiber to the second ferrule, A step of preparing a jig having a first jig fitting portion and a second jig fitting portion in place of the casing member, The first fitting portion and the second fitting portion are fitted into the first jig fitting portion and the second jig fitting portion, respectively, thereby housing at least a portion of the first plug assembly and the second plug assembly in the jig such that the axial positions of the tip of the first ferrule and the tip of the second ferrule are different, and the jig is held in place by the holding member. A step of simultaneously obliquely polishing the first ferrule and the second ferrule, After the oblique polishing step, the casing member is used to house at least a portion of the first plug assembly and the second plug assembly, and the casing member is held by the holding member. A ferrule polishing method including the following.

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