Patent Application
20090252460
The present invention relates to an optical connector for an optical fiber cord, and also to a method of attaching an optical fiber cord to the optical connector.
The demand for high-speed data communications has increased in accordance with the spread of Internet, and the so-called Fiber-To-The-Home (FTTH) services in which optical fibers are installed in each home are also expanding. Thus, it is expected that an optical connector for optical connection will be used in a general home. For example, it is considered to attach an optical connector to the end of an optical fiber cord that is attached to optical communication equipment in the home and to insert the plug of the optical connector into an adapter provided in the wall for optical connection, so that the optical communication equipment in the home is connected with the FTTH network.
An optical connector known for such use is a connector suitable for field (indoor) assembly, having a structure which comprises a built-in optical fiber-containing capillary provided at the tip and a mechanical splice provided at the rear inside. Japanese Patent Application Publication No. 2001-235656 discloses an SC connector having a built-in mechanical splice that enables field assembly, as well as tools and method for assembling a field-assembly optical connector so as to be attached to an end of an optical fiber cord. In the disclosed technique, the optical connector is assembled using an optical connector assembly tool that is equipped with a connector support stand, a fiber support stand for clamping an optical fiber cord, a tension member fixing tool for fixing a tension member exposed at the end of the optical fiber cord, and a moving mechanism for moving the connector support stand back and forth relative to the fiber support stand.
In order to obtain stable optical and mechanical characteristics, the optical connector attached to the end of the optical fiber cord must endure the force that is applied from the outside to the optical fiber cord. For example, the optical connector is required not only to hold the sheath of an optical fiber cord but also to allow the tension member of the optical fiber cord to be fixed to the optical connector so that the tension member may bear the tension acting on the optical fiber cord.
It has been difficult to assemble a conventional field-assembly optical connector in a manner such that a tension member is fixed while a sheath is held, and generally the assembly work has been complex. Also, since the conventional field-assembly optical connector has an additional structure for enabling field-assembly, its structure has been complicated. For example, in the case of the optical connectors described in Japanese Patent Application Publication No. 2001-235656, it has been necessary to use an optical connector assembly tool having a tension member fixing jig so that a tension member may be fixed, and consequently the connector assembly work is also complex.
[Patent document 1] Japanese Patent Application Publication No. 2001-235656
An object of the present invention is to provide an optical connector having a simple structure allowing ease in the work of attaching an optical fiber cord thereto and a method of attaching an optical fiber cord to the optical connector.
In order to solve the problems, an optical connector to be attached to an optical fiber cord comprising an optical fiber, a tension member arranged around the optical fiber, and a sheath comprises (1) a plug part which has a built-in optical fiber-containing capillary provided at the front and which includes a mechanical splicing portion that can allow an optical fiber to be inserted from the rear so as to be fixed therein, (2) a calking stand into which an optical fiber cord is inserted, (3) a calking ring which is provided outside the calking stand so as to hold the tension member between the calking ring and the calking stand and which causes the calking stand to radially contract so that the calking stand may hold the sheath, and (4) a coupling body which is provided behind the plug part and which accommodates the calking stand and the calking ring. Here, the term “at the front of the optical connector” means the front side that faces a counter part to be connected therewith.
In the optical connector relating to the present invention, the calking stand may have a slit and also may have nail-shaped protuberances at the inner circumferential surface. The calking stand may also have a cylindrical portion and a flange portion and a calking ring is provided around the cylindrical portion. The flange portion is provided at the rear of the cylindrical portion and may have a groove for accommodating a tension member. In addition, the calking stand may be regulated with respect to displacement in terms of the turning direction relative to the plug part. The coupling body may be equipped with a fastening part for fastening the calking stand in the condition in which the calking stand is accommodated therein.
In another aspect of the present invention, a method of attaching to an optical connector an optical fiber cord having an optical fiber, a tension member arranged around the optical fiber, and a sheath is provided. The method comprises: (1) preparing the optical fiber cord which is inserted into a calking stand and the sheath of which is removed at the end portion; (2) folding back the tension member over the outside of the calking stand, and press-fitting the folded-back tension member to the inside of the calking ring together with the calking stand, and causing the calking stand to radially contract so that the tension member may be held between the calking stand and the calking ring and at the same time the calking stand may hold the sheath; (3) removing the coating of the optical fiber and cutting the optical fiber to a predetermined length; (4) inserting the optical fiber into a plug part which has a built-in fiber-containing capillary at the front and which has a mechanical splicing portion that allows an optical fiber to be inserted from the rear so as to be fixed, and fixing the optical fiber by closing the mechanical splicing portion in the state in which the built-in fiber and the optical fiber are butted against each other; and (5) housing the calking stand in the coupling body provided behind the plug part.
In the method of attaching an optical fiber cord to an optical connector relating to the present invention, at the time of putting a tension member between the calking stand and the calking ring, the tension member may be accommodated in grooves formed in the calking stand.
With an optical connector of the present invention and the method of attaching an optical fiber cord to the optical connector, it is possible to fix a tension member by holding the tension member between the calking stand and the calking ring. In that case, the calking stand is radially contracted so that the sheath of the optical fiber cord is held. Also, the optical fiber of the optical fiber cord is inserted into and fixed in the mechanical splicing portion in the plug part, and the calking stand and the calking ring which have fixed the sheath and the tension member are housed in the coupling body provided behind the plug part. That is, the structure for fixing a sheath and a tension member to the optical connector is simple, and it is possible to easily perform the assembly work of the optical connector without using a jig for fixing the tension member beforehand.
In
1: optical connector, 2: plug part, 3: plug housing, 4: plug frame, 5: capillary, 6: built-in fiber, 7: mechanical splicing portion, 20: coupling body, 27: fastening piece (fastening part), 30: cover member, 35: calking stand, 37: slit, 41: groove, 42: nail-shaped protuberance, 45: calking ring, 50: optical fiber cord, 51: optical fiber, 52: tension member, 53: sheath, 60: press-fitting jig, 100: assembly tool.
Hereinafter, preferred embodiments of the present invention will be described in reference to the accompanying drawings. The drawings are provided for the purpose of explaining the embodiments and not intended to limit the scope of the invention. In the drawings, an identical mark represents the same element so that the repetition of explanation may be omitted. The dimensional ratios in the drawings are not always exact.
The following properties are required of the optical fiber cord, for example: the tension member does not move in a longitudinal direction relative to the optical fiber so that mechanical characteristics may be maintained; and the optical fiber cord has flexibility allowing ease in bending at the time of wiring and storage. In order to prevent the movement of the tension member, it is desirable that the tension member be arranged at high density inside the sheath (so-called tight structure); however, the control should be done to the degree that the spring back mobility of the optical fiber may not be lost. Also, in order to prevent the transmission characteristics from being degraded due to the lateral pressure, the thicker the sheath, the more preferable.
Next, the description of each part of the optical connector 1 will be given.
Two windows 9 which are the openings provided corresponding to two wedge notches 8 on one side of the plug frame 4 (see
A capillary 5 including a built-in fiber 6 is attached to the front end of the mechanical splicing portion 7 (see
A fiber introducing hole 16, whose diameter is gradually decreased to guide the optical fiber toward an optical fiber holding hole when the optical fiber is inserted from the rear, is provided at the rear end of the mechanical splicing portion 7. Also, the mechanical splicing portion 7 is equipped with a clamp member (illustrated in an integral form in the figure) which functions to generate holding force to hold the inserted optical fiber.
When the optical connector 1 is connected with the coupling counterpart, the mechanical splicing portion 7 receives rearward force at a time of butting between the capillary 5 provided in the tip portion thereof and the coupling counterpart. In such case, the mechanical splicing portion 7 is afforded with forward pressing force by the elasticity resilient force of the coil spring 13, and accordingly a force is generated so as to mutually push the connecting faces between the coupling counterpart and the built-in fiber 6 of the capillary 5 such that the connection condition is maintained.
One of the side-faces of the coupling body 20 is open at the portion on the rear end side, and a caulking portion accommodating-space 25 is provided there so as to accommodate a calking stand 35 and a calking ring 45 which are attached to the optical fiber cord 50. Also, a fiber introducing hole 24 whose diameter is gradually reduced toward the front is provided in the front portion beyond the calking portion accommodating-space 25. The front end of the fiber introducing hole 24 reaches a position near the rear end of the mechanical splicing portion 7 and has a diameter smaller than the opening diameter of a fiber introducing hole 16 of the mechanical splicing portion 7. Therefore, the tip of the optical fiber 51 inserted from the coupling body 20 can be guided to be inserted into the mechanical splicing portion 7 without suffering from bumping.
Also, the coupling body 20 has fastening pieces (fastening parts) 27 respectively extending toward the rear from the side walls 26 of the calking portion accommodating-space 25, and fastening holes 28 are formed in the fastening pieces 27. When the calking stand 35 is being accommodated, the fastening pieces 27 interfere with the calking stand 35 and accordingly are elastically deformed toward the outside, and when a fastening protuberance 40 (see
In
Also, the calking stand 35 has a fastening protuberance 40 provided on the side face of the flange portion 38 thereof, so that when the calking stand 35 is housed in the pre-determined position of the calking portion accommodating-space 25, the fastening protuberance 40 is fastened in the fastening hole 28 of the coupling body 20 and holds the calking stand 35 in the calking portion accommodating-space 25. The fastening protuberance 40 has a substantially square shape so that a displacement in the turning direction of the calking stand 35 (that is, a displacement relative to the turning direction of the plug part 2) is effectively regulated when it is fastened in the fastening hole 28 having a like square shape. The flange portion 38 has two grooves 41 formed in one side face thereof so that the tension member 52 may be placed in bundles therein in the axial direction.
The calking ring 45 can be press-inserted over the cylindrical portion 36 of the calking stand 35 from a front position so that the tension member 52 of the optical fiber cord 50 may be held between the calking ring 45 and the cylindrical portion 36. The portion of the tension member 52 that extends beyond the rear of the calking ring 45 can be stored in grooves 41 provided on the flange portion 38 of the calking stand 35.
Next, an explanation will be given about the method of attaching an optical fiber cord 50 to the optical connector 1. For attaching the optical fiber cord 50 to the optical connector 1, first, the optical fiber cord 50 is inserted into the inside of the calking stand 35 from the behind, and the sheath 53 is removed by a predetermined length from the end portion of the optical fiber cord 50 so as to expose the optical fiber 51 and the tension member 52. In such case, the length at which the optical fiber 51 is exposed is a distance that is longer than the distance between the front end of the calking stand 35 and the position where the optical fiber 51 is connected with the built-in fiber 6 in the mechanical splicing portion 7 as shown in
Subsequently, the positions of the end of the sheath 53 and the front end of the calking stand 35 are adjusted beforehand, and then the tension member 52 exposed at the front of the calking stand 35 is folded back over the outside of the calking stand 35 so as to be disposed in bundles in the grooves 41 of the flange portion 38. In this condition, the calking ring 45 is attached outside the cylindrical portion 36 from the front of the calking stand 35, and the calking stand 35 is, together with the tension member 52 thus folded back, pushed into the calking ring 45. At that time, the calking stand 35 is radially contracted due to the compression force provided by the calking ring 45, and consequently the sheath 53 of the optical fiber cord 50 is firmly held. Also, the folded-back tension member 52 is firmly held between the calking stand 35 and the calking ring 45. In this case, the tighter the tension member 52 of the optical fiber cord 50 is housed in the sheath 53, the more easily can the terminal treatment, such as the attachment of the calking ring 45, for the optical fiber cord 50 be done, because the optical fiber 51 and the tension member 52 do not move in a longitudinal direction.
The slide member 64, which is structured to move back and forth on the base member 61, has a groove 65 formed to evade the interference with the optical fiber 51 exposed at the front of the calking stand 35. The rear end face (the right rear surface in
Next, the coating of the tip portion of the optical fiber 51 is removed and cut by a predetermined length.
After the optical fiber 51 is cut to a predetermined length, the optical fiber 51 is inserted from the fiber introducing hole 24 of the coupling body 20 into the mechanical splicing portion 7 of the plug part 2. In such case, the mechanical splicing portion 7 is made open beforehand by inserting a wedge into a wedge notch 8 of the mechanical splicing portion 7. The diameter of the fiber-introducing hole 24 gradually decreases toward the front end such that the front end diameter becomes smaller than the opening diameter of the fiber introducing hole 16 of the mechanical splicing portion 7. Therefore, the tip of optical fiber 51 can be guided to be inserted into the mechanical splicing portion 7 without bumping. Prior to such operation, the plug part 2 is assembled beforehand by putting the mechanical splicing portion 7 into the plug frame 4 and attaching the plug housing 3, and moreover the coupling body 20 is attached to the rear of the plug frame 4 beforehand. In this case, the cover member 30 may be attached to the coupling body 20 and made open beforehand.
Once the calking stand 35 is held in the calking portion accommodating-space 25, the wedge is pulled out from the wedge notch 8 of the mechanical splicing portion 7, and then the mechanical splicing portion 7 is closed. Thus, the optical fiber 51 is fixed in the mechanical splicing portion 7 in the state where it is connected with the built-in fiber 6. In such case, the calking stand 35 is held in the calking portion accommodating-space 25 by the fastening of the fastening protuberance 40 and the fastening hole 28. Therefore, it is possible to pull out the wedge from the wedge notch 8 of the mechanical splicing portion 7 while maintaining the condition of the connection between the optical fiber 51 and the built-in fiber 6. Consequently, the reliability of the optical connector 1 can be secured.
The bending part 103 is equipped with a hinge plate 111 that is engaged in the connector holder 102 on the rear end side so as to be turnably connected. A metallic or plastic wedge 112, which has a U-shaped form by a side view, is attached to the hinge plate 111 through the hinge plate 111. One pair of wedge prominences 112a and 112b of the wedge 112 are protruded from a window 114 formed in the connector holder 102. The wedge 112 is held by a stopper 115 which is fixed to the hinge plate 111.
The optical connector 1 is held in the connector holder 102 by holding walls 104. The connector holder 102 has a head part 116 provided at the tip thereof in a manner such that the head part is movable in the longitudinal direction. The head part 116 has a nail part 116a, and by moving the head part 116 toward the connector holder 102, the slope portion 116b at the tip of the nail part 116a enters between the connector holder 102 and the hinge plate 111. Thus, the hinge plate 111 is separated from the connector holder 102. The cord holder 101 is structured so as to hold the optical fiber cord 50 behind the connector holder 102.
Once the optical connector 1 is set in an assembly tool 100, such as the above-described one, and the built-in fiber 6 and the optical fiber 51 are butted together, the head part 116 is moved toward the connector holder 102. In this way, the slope portion 116b enters between the connector holder 102 and the hinge plate 111, whereby the hinge plate 111 is separated from the connector holder 102, thereby causing the bending part 103 to bend relative to the connector holder 102 at the connection part. Thus, the wedge prominences 112a and 112b are pulled out of the wedge notch 8 of the mechanical splicing portion 7, allowing the mechanical splicing portion 7 to be closed to hold the optical fiber 51 in a sandwiching manner so that a stable connection condition is secured.
As described above, according to the optical connector 1 of the present invention and the method of attaching the optical fiber cord to the optical connector according to the present invention, the tension member 52 can be fixed by sandwiching it between the calking stand 35 and the calking ring 45. In that case, the calking stand 35 is radially contracted to hold the sheath 53 of the optical fiber cord 50. Also, the optical fiber 51 of the optical fiber cord 50 is inserted into and fixed in the mechanical splicing portion 7 of the plug part 2, and the calking ring 45 and the calking stand 35 in which the sheath 53 and the tension member 52 are fixed are housed in the coupling body 20 which is attached to the rear of the plug part 2. That is, the structure to fix the sheath 53 and the tension member 52 on the optical connector 1 is simple, and also the assembly work of the optical connector 1 can easily be accomplished without using a jig or the like for fixing the tension member 52 beforehand.
In the case of the calking stand 35 of the optical connector 1 according to the above-described embodiment, the cylindrical portion 36 on the front side and the flange portion 38 on the rear side are both made of hard plastic. However, the cylindrical portion 36 may be constituted of metal such as brass. In that case, the cylindrical portion 36 does not easily suffer from elastic deformation, and accordingly the power of sandwiching to hold the tension member 52 with the calking ring 45 is enhanced. Furthermore, the cylindrical portion 36 does not easily suffer from plastic deformation, and therefore the power to sandwich to hold the tension member 52 can be maintained for a long period of time.
The present patent application is based on a Japanese patent application (Tokugan 2006-108102) filed on Apr. 10, 2006, and the contents thereof are incorporated herein as the reference.
The optical connector of the present invention can be attached to the terminal of an optical fiber cord which is provided for domestic optical communication equipment, and it is suitable as an optical connector to be assembled in field (indoor assembly).
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-108102 | Apr 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/057813 | 4/9/2007 | WO | 00 | 9/29/2008 |
