JP3965783B2 - Optical connector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical connector, and more particularly to an optical connector for connecting optical fibers to each other.
[0002]
[Prior art]
Conventionally, there is JP-A-9-159860 as a technology in such a field. The optical connector described in this publication is for optical connection using buckling of an optical fiber. Specifically, an optical fiber is protruded by a predetermined amount from the distal end surface of the ferrule, and an optical fiber bending space that allows buckling of the bowed optical fiber is formed inside the ferrule. Therefore, this optical connector realizes PC connection (Physical Contact) by buckling.
[0003]
[Problems to be solved by the invention]
However, since the conventional optical connector is configured as described above, the following problems exist.
[0004]
That is, when an optical fiber is buckled like a bow in the optical fiber bending space, an excessive load is applied to the optical fiber due to this buckling, and an optical transmission loss occurs in the optical fiber in the ferrule. There is a problem that the optical fiber may break.
[0005]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical connector in which optical transmission loss of an optical fiber is less likely to occur in a ferrule and there is no possibility of optical fiber breaking. .
[0006]
[Means for Solving the Problems]
The optical connector of the present invention according to claim 1 is an optical connector having a ferrule with a built-in optical fiber.
An optical fiber is inserted into an optical fiber insertion portion that extends from the optical connection port formed on the front end surface of the ferrule toward the inside of the ferrule, and the front end surface of the optical fiber protrudes from the optical connection port. A non-fixed area located in the vicinity of the front end surface of the optical fiber, and a fixed area located behind the non-fixed area. In the non-fixed area, the optical fiber is disposed with a clearance in the optical fiber insertion portion. , have a following region length 500μm from the front end face of the ferrule,
The optical fiber insertion portion includes an optical fiber positioning hole that extends from the optical connection port and forms a non-fixed region, and an optical fiber alignment groove that is positioned behind the optical fiber positioning hole and forms a fixed region. The optical fiber alignment groove has a fiber pressing and fixing member for pressing the optical fiber from above to fix the optical fiber to the wall surface of the optical fiber alignment groove .
[0007]
In this optical connector, the optical fiber is fixed to the vicinity of the front end face of the ferrule with respect to the ferrule, so that the optical fiber is very unlikely to buckle in the ferrule. Moreover, as a result of shortening the non-fixed region, the change in the protruding amount of the optical fiber caused by the difference in thermal expansion coefficient between the ferrule and the optical fiber can be made extremely small. Therefore, the optical connector of the present invention proposes a new concept of PC connection in order to avoid the problem of PC connection using buckling. And in the case of PC connection using buckling, it is optimal that the non-fixed area is 500 μm or less from the front end face of the ferrule without the refractive index matching agent being present in the non-fixed area. They found out.
[0009]
Further, in this optical connector, the optical fiber insertion portion has an optical fiber positioning hole extending from the optical connection port to form a non-fixed area, and a substantially C-shaped cross section that is positioned behind the optical fiber positioning hole to form the fixed area. consists of a fiber alignment groove, by pressing the optical fiber of the optical fiber alignment groove from above, that having a fiber pressing and fixing member for fixing the optical fiber on the wall surface of the optical fiber alignment groove. When such a configuration is adopted, the optical fiber can be easily and reliably fixed to the ferrule simply by placing the optical fiber in the optical fiber alignment groove and pressing the optical fiber from above by the optical fiber pressing and fixing member. Can do.
[0011]
3. The optical connector according to claim 2, wherein the end face of the optical fiber is preferably subjected to edge removal processing by electric discharge machining. In this case, the optical fiber can be inserted into the optical fiber insertion portion of the ferrule while the tip of the optical fiber is electrically rounded.
[0012]
4. The optical connector according to claim 3, wherein the end face of the optical fiber is preferably subjected to edge removal processing by polishing. In this case, the optical fiber can be inserted into the optical fiber insertion portion of the ferrule while the tip of the optical fiber is mechanically rounded.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of an optical connector according to the present invention will be described in detail with reference to the drawings.
[0014]
FIG. 1 is a perspective view showing an optical connector according to the present invention. The optical connector 1 shown in the figure constitutes the plug side of the SC type connector. The optical connector 1 allows one-touch connection by being inserted from both sides of the adapter 2. The optical connector 1 has a ferrule 3 protruding from the end thereof, and the ferrule 3 is formed in a cylindrical shape by a material such as zirconia, plastic or glass as shown in FIG. The optical fiber 5 exposed by removing the covering portion F from the tip of the optical fiber core S is fixed inside.
[0015]
As shown in FIGS. 3 and 4, an optical fiber insertion portion 4 extending in the central axis direction for loading the optical fiber 5 and a covering portion insertion for loading the covering portion F are inserted in the center of the ferrule 3. The holes 6 are arranged in parallel on a straight line. The optical fiber insertion portion 4 is formed as an optical fiber positioning hole extending over the entire length, has a diameter of 126 μm with respect to the optical fiber 5 having a diameter of 125 μm, and the optical fiber 5 has a slight clearance. It will be inserted into the optical fiber insertion part 4.
[0016]
The front end surface 5a of the optical fiber 5 protrudes from the optical connection port 3A with a protrusion amount of about 2 μm from the front end surface 3a of the ferrule 3. The optical fiber insertion portion 4 has a non-fixed region P located in the vicinity of the front end surface 3a of the ferrule 3 and a fixed region N positioned behind the non-fixed region P. The non-fixed area P has an area length of 500 μm or less (preferably 50 to 100 μm) extending inward from the front end face 3a of the ferrule 3, and the non-fixed area P is connected to the PC connection. It is also a region where there is no liquid material such as an unnecessary refractive index matching agent.
[0017]
Further, in the optical fiber insertion portion 4, an adhesive (for example, epoxy-based thermosetting adhesive) R is loaded in the fixing region N, and the adhesive R causes the outer peripheral surface of the optical fiber 5 and the optical fiber insertion portion 4 to be fixed. Is fixed to the wall. As described above, the optical fiber insertion portion 4 is filled with the adhesive R leaving a slight non-fixed region P located in the vicinity of the front end surface 3 a of the ferrule 3. The covering portion F of the optical fiber core S is inserted into the covering portion insertion hole 6, and the outer peripheral surface of the covering portion F and the wall surface of the covering portion insertion hole 6 are bonded and fixed by the adhesive R.
[0018]
Here, the procedure for assembling the optical fiber core wire S to the ferrule 3 will be briefly described with an example.
[0019]
First, the coating portion F on the front side of the optical fiber core wire S is removed by a predetermined length, the optical fiber 5 is exposed from the tip portion of the optical fiber core wire S, and then the optical fiber 5 is fixed to a predetermined length by a cutter or the like. Cut it up. After that, as shown in FIG. 5, the tip surface 5a of the optical fiber 5 is subjected to electric discharge machining to form a spherical shape and perform edge removal processing. The biggest reason why electric discharge machining is performed is that it is easy to cause PC coupling by removing the burr on the end face 5a of the optical fiber 5 which is a factor inhibiting PC coupling and rounding the end face. As a result of rounding, The optical fiber 5 is easily inserted into the optical fiber insertion portion 4 of the ferrule 3. In addition, as shown in FIG. 6, the front end surface 5a of the optical fiber 5 may be chamfered by a polishing rotor or mechanical polishing by manual work, and the edge removal processing of the front end surface 5a of the optical fiber 5 may be performed. .
[0020]
After such end face processing, the optical fiber 5 is inserted into the optical fiber insertion portion 4 of the ferrule 3, and at this time, the grease is provided in the optical connection port 3 </ b> A of the ferrule 3 so as to correspond to the non-fixed region P. A refractive index matching agent or an adhesive having elasticity is preliminarily packed. Then, in a state where a predetermined amount of adhesive R is applied to the optical fiber 5 and the covering portion F, the optical fiber 5 is inserted into the optical fiber insertion portion 4 from the rear, and the front end surface 5a of the optical fiber 5 is connected to the front end surface of the ferrule 3 Push in so that it protrudes from 3a by about 2 μm.
[0021]
In this case, the tip of the optical fiber 5 is inserted into the refractive index matching agent, and when the optical fiber 5 moves forward, the adhesive R applied to the optical fiber 5 is an adhesive of a refractive index matching agent having a large viscosity. Due to the exclusion phenomenon, it is excluded from the surface of the optical fiber 5. As a result, the adhesive R does not adhere to the tip portion of the optical fiber 5 that has passed through the refractive index matching agent, and the optical fiber 5 to which the adhesive R does not adhere protrudes from the ferrule 3. Then, after the adhesive R is cured, the refractive index matching agent is removed, so that the portion where the refractive index matching agent was present is formed as the non-fixed region P in the optical fiber insertion portion 4. .
[0022]
The refractive index matching agent or the elastic adhesive may be abutted in a state where the front end surface 5a of the optical fiber 5 protrudes from the front end surface 3a of the ferrule 3 without being packed in the optical connection port 3A in advance. . Further, the optical fiber insertion portion 4 of the ferrule 3 may be filled with the adhesive R in advance.
[0023]
Next, an optical connector 7 according to another embodiment will be described. The optical connector 7 is an adhesive-free optical connector.
[0024]
As shown in FIG. 7, the front end face 8a of the ferrule 8 is formed flat in order to achieve end face butting with the counterpart optical connector, and the optical fiber 5 protrudes from the center of the front end face 8a. An optical connection port 9 is provided. Further, guide pin insertion holes G used for connecting the optical connectors 7 are provided on both sides of the optical connection port 9.
[0025]
As shown in FIGS. 7 and 8, a single optical fiber insertion portion 10 extending in the longitudinal direction for inserting the optical fiber 5 is formed in a straight line inside the ferrule 8. The optical fiber insertion portion 10 has an optical fiber positioning hole 11 that extends from the optical connection port 9 and is used as a non-fixed region P, and a cross-section that is positioned behind the optical fiber positioning hole 6 and used as a fixed region N. It consists of a C-shaped optical fiber alignment groove 12. A block-shaped optical fiber pressing and fixing member 13 is disposed above the optical fiber alignment groove 12, and the fiber pressing and fixing member 13 is disposed in an accommodating portion 14 to be described later.
[0026]
A tapered (for example, funnel-shaped) optical fiber guide hole 10A in consideration of insertion of the optical fiber 5 is provided behind the optical fiber alignment groove 12, and the optical fiber positioning hole 11, the optical fiber alignment groove 12, and the light are aligned. The fiber guide holes 10A are arranged on a straight line. Accordingly, when the distal end portion of the optical fiber 5 is inserted from the optical fiber guide hole 10 </ b> A, the optical fiber 5 reaches the optical fiber positioning hole 11 through the optical fiber alignment groove 12.
[0027]
Further, the ferrule 8 is provided with a fiber pressing and fixing member accommodating portion 14 for accommodating the fiber pressing and fixing member 13, and the top of the accommodating portion 14 has a rectangular opening for inserting the fiber pressing and fixing member 13. 15 and the opening 15 is formed on the upper surface 8 c of the ferrule 8. An optical fiber alignment groove 12 having a substantially C-shaped cross section extending over the entire length is formed on the bottom surface 14a of the housing portion 14.
[0028]
Therefore, when the fiber pressing and fixing member 13 is inserted from the opening 15, the fiber pressing and fixing member 13 can be disposed in the optical fiber alignment groove 12, and the optical fiber 5 in the optical fiber alignment groove 12 is connected to the fiber pressing and fixing member. 13 can be pressed down from above (see FIG. 9). Therefore, in the optical fiber insertion portion 10, the fixing region N is formed with substantially the entire length of the fiber pressing and fixing member 13. The non-fixed region P is formed in front of the fixed region N. The non-fixed region N having a region length of 500 μm or less (preferably about 50 to 100 μm) is formed by the optical fiber positioning hole 11. It is secured.
[0029]
Further, the optical connector 7 has a spring member 16 that urges the fiber pressing and fixing member 13 inserted into the housing portion 14, and the spring member 16 extends from the upper surface 8 c of the ferrule 8 to the lower surface 8 d. The clamp member 16 is configured to elastically hold the fiber pressing and fixing member 13 in the accommodating portion 14. Further, a protrusion 17 extending in the longitudinal direction is provided on the upper surface 13 a of the fiber pressing and fixing member 13, and the spring force of the clamp member 16 is transmitted to the fiber pressing and fixing member 13 through the protrusion 17. Yes.
[0030]
The clamp member 16 is made of phosphor bronze or cold-worked stainless steel, so that the clamp member 16 having a strong spring force and high durability is possible, and long-term reliability of the clamp force is ensured. The clamp member 16 is formed in a U shape from a plate-like upper piece 16a, a lower piece 16b, and an intermediate piece 16c connecting them, and creates an appropriate clamping force by the upper piece 16a of the clamp member 16. .
[0031]
Further, as shown in FIGS. 7 and 8, a block for fixing the covering portion F of the optical fiber core wire S to the ferrule 8 separately from the fiber pressing and fixing member 13 for fixing the optical fiber 5 to the ferrule 8. The cover portion pressing fixing member 20 has a shape.
[0032]
The ferrule 8 is provided with a covering portion seating groove 22 having a V-shaped cross section located behind the funnel-shaped optical fiber guide hole 10A. The covering portion seating groove 22 has a width for accommodating the covering portion F. It is formed as a V-groove. The covering portion seating groove 22 is formed on the bottom surface of the covering portion pressing and fixing member accommodating portion 21 provided in parallel with the fiber pressing and fixing member accommodating portion 14 described above. The fixing member 20 is disposed.
[0033]
Further, the optical connector 7 has a spring member 23 that biases the covering portion pressing and fixing member 20 in the housing portion 21, and the spring member 23 extends from the upper surface 8 c of the ferrule 8 to the lower surface 8 d. The clamp member 23 is configured as a U-shaped clamp member, and the cover member pressing and fixing member 20 is elastically held in the housing portion 21 by the clamp member 23. Further, a projection 24 extending in the longitudinal direction is provided on the upper surface 20 a of the covering portion pressing and fixing member 20, and the covering portion F is pressed into the covering portion insertion groove 22 by the covering portion pressing and fixing member 20. Fixed.
[0034]
In addition, by using phosphor bronze or cold-worked stainless steel as the material of the clamp member 23, the clamp member 23 having a strong spring force and high durability is possible, and long-term reliability of the clamp force is ensured. The clamp member 23 is formed in a U shape from a plate-like upper piece 23a, a lower piece 23b, and an intermediate piece 23c connecting them, and creates an appropriate clamping force by the upper piece 23a of the clamp member 23. .
[0035]
Next, an optical connector 30 according to still another embodiment will be described. The optical connector 30 is an adhesive type optical connector.
[0036]
The optical connector 30 shown in FIG. 10 has a ferrule 32, and the ferrule 32 is provided with an optical fiber bonding concave portion 33 for accommodating the adhesive R, and the top of the concave portion 33 has an adhesive R attached thereto. It is formed as a rectangular opening 34 for inflow. An optical fiber insertion portion 37 is formed in the ferrule 32, and an optical fiber alignment groove 35 having a C-shaped cross section extending over the entire length is formed on the bottom surface 33a of the concave portion 33. An optical fiber positioning hole 36 is formed (see FIG. 11).
[0037]
Therefore, in the same manner as the optical connector 1 in FIG. And the tip of the optical fiber 5 is projected from the front end face 32 a of the ferrule 32. Thereafter, when the adhesive R is poured from the opening 34, the optical fiber 5 in the optical fiber insertion portion 37 is fixed to the ferrule 32 by the adhesive R, and this becomes the fixing region N. The portion from which the refractive index matching agent has been removed becomes the non-fixed region P.
[0038]
The ferrule 32 has a rear end formed with a covering portion bonding concave portion 38 arranged in parallel with the optical fiber bonding concave portion 33. When the adhesive R is poured into the concave portion 38, the covering portion F becomes: The adhesive R is securely fixed to the ferrule 32.
[0039]
Here, in the present invention, when the cut optical fiber 5 is used and the end face angle of the tip face 5a of the optical fiber 5 attached at the time of cutting is relaxed, a discharge is applied to the tip face 5a of the optical fiber 5 to round it. There is also. For example, when the tip surface 5a of the optical fiber 5 has an angle of 1.5 °, the distance from the tip of the optical fiber 5 to the center of the core is about 1.6 μm. Therefore, if a discharge is applied to the tip surface 5a and the tip surface 5a is processed to have a curvature radius of 1.0 mm, the optical fiber 5 having such a curvature radius must still be deformed to be PC. Therefore, as shown in FIG. 12, it is necessary to protrude the front end surface 5a of the optical fiber 5 from the front end surface 3a of the ferrule 3 in consideration of this. In other words, the tip surface 5a of the optical fiber 5 hardly has a cutting angle of 1.5 ° or more. However, in the unlikely event, the protruding amount of the optical fiber 5 is 1 to 2 μm, and the maximum is about 5 μm. To do.
[0040]
On the other hand, as shown in FIG. 13, in the conventional ferrule 100, the optical fiber 101 is attached to the ferrule 100 for realizing the PC, and then precision polishing is performed, so that the tip surface 101a of the optical fiber 101 is a spherical surface. It is processed into. The radius of curvature at that time is about 20 mm, and this spherical surface slightly protrudes from the front end surface 100a of the ferrule 100, facilitating PC. However, in reality, four types of precision polishing processes are required, and the ratio of the optical connector to the manufacturing cost is large, which has been a problem in reducing the cost.
[0041]
The present invention is not limited to the above-described embodiment, and the optical fiber core S may be a 2-16 core fiber, and the optical connector is FC type, SC type. Any type such as an MT type may be used.
[0042]
【The invention's effect】
Since the optical connector according to the present invention is configured as described above, the following effects are obtained. That is, the optical fiber is inserted into the optical fiber insertion portion extending from the optical connection port formed in the front end surface of the ferrule toward the inside of the ferrule, the tip surface of the optical fiber is protruded from the optical connection port, and the optical fiber insertion portion is , Having a non-fixed region located in the vicinity of the front end surface of the ferrule and a fixed region located behind the non-fixed region, in which the optical fiber is disposed with a clearance in the optical fiber insertion portion, and is not fixed region, possess the following areas length 500μm from the front end face of the ferrule, the optical fiber insertion portion includes an optical fiber positioning holes constituting the non-fixed region extends from the optical connection port, located behind the optical fiber positioning holes An optical fiber alignment groove having a substantially C-shaped cross section forming a fixed region, and pressing the optical fiber in the optical fiber alignment groove from above, The by having a fiber pressing fixing member for fixing the optical fiber, the optical transmission loss hardly occurs in the optical fiber within the ferrule, allowing neither the optical connector fear of breakage of the optical fiber.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of an optical connector according to the present invention.
FIG. 2 is a perspective view showing a ferrule adapted to the optical connector of FIG.
3 is a longitudinal sectional view of the ferrule of FIG. 2. FIG.
4 is an enlarged cross-sectional view of a main part of FIG. 3;
FIG. 5 is an enlarged side view showing a state in which the tip surface of the optical fiber is subjected to electric discharge machining.
FIG. 6 is an enlarged side view showing a state where the tip surface of the optical fiber is polished.
FIG. 7 is an exploded perspective view showing another embodiment of the optical connector according to the present invention.
8 is a longitudinal sectional view of the optical connector shown in FIG.
FIG. 9 is an enlarged cross-sectional view showing a state in which an optical fiber is fixed in an optical fiber alignment groove.
FIG. 10 is a cross-sectional view showing still another embodiment of the optical connector according to the present invention.
11 is an enlarged cross-sectional view of a main part of the optical connector shown in FIG.
FIG. 12 is an enlarged cross-sectional view showing a state in which an optical fiber is inserted into a ferrule in the optical connector of the present invention.
FIG. 13 is an enlarged cross-sectional view showing a state in which an optical fiber is inserted into a ferrule in a conventional optical connector.
[Explanation of symbols]
P: non-fixed region, N: fixed region, R: adhesive, 1, 7, 30 ... optical connector, 3, 8, 32 ... ferrule, 3a, 8a, 32a ... front end surface of ferrule, 3A, 9, 38 ... Optical connection port 4, 10, 37 ... optical fiber insertion portion, 5 ... optical fiber, 5a ... optical fiber tip surface, 11, 36 ... optical fiber positioning hole, 12, 35 ... optical fiber alignment groove, 13 ... fiber pressing Fixed member.

Claims (3)

In an optical connector having a ferrule with a built-in optical fiber,
The optical fiber is inserted into an optical fiber insertion portion extending from the optical connection port formed on the front end surface of the ferrule toward the inside of the ferrule, and the front end surface of the optical fiber is projected from the optical connection port, and the light The fiber insertion portion has a non-fixed region located in the vicinity of the front end surface of the ferrule, and a fixed region located behind the non-fixed region, and the optical fiber is the optical fiber in the non-fixed region. are arranged with clearance in the insertion portion, the non-fixed region, have a following region length 500μm from the front end face of the ferrule,
The optical fiber insertion portion includes an optical fiber positioning hole extending from the optical connection port and forming the non-fixed region, and an optical fiber having a substantially C-shaped cross section positioned behind the optical fiber positioning hole and forming the fixed region. An optical connector comprising: an alignment groove; and a fiber pressing and fixing member that presses the optical fiber in the optical fiber alignment groove from above and fixes the optical fiber to a wall surface of the optical fiber alignment groove . The tip surface, the optical connector according to claim 1, characterized in that it is the edge removal process by electric discharge machining of the optical fiber. The tip surface, the optical connector according to claim 1, characterized in that it is the edge removal process by polishing of the optical fiber.

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