JP5421854B2 - Optical fiber coating removal method, coating removal member, and optical connection member - Google Patents

Description

  The present invention relates to an optical fiber coating removal method, a coating removal member, and an optical connection member provided with a coating on the outer periphery of a bare optical fiber.

  2. Description of the Related Art An optical connector is known as an optical connection member that facilitates the work of attaching to an optical fiber and shortens the work time in a work site where an optical line is constructed (see, for example, Patent Document 1). In this optical connector, the optical fiber is fixed with a surplus length so as to bend inside, so that it can be bonded to the built-in optical fiber without using an adhesive, and the optical fiber and the built-in optical fiber are always bonded to the bonding surface. By pressing the pressing force, a reliable joining state can be maintained.

  Furthermore, this type of optical connector has a coating removal part inside, the optical fiber is bent by the insertion force, and the coating is removed by the coating removal part, so that it can be mounted on the optical fiber with a simple connection work. There is something that can be done. As shown in FIG. 18A, in this optical connector, when the optical fiber 501 is inserted, the coating removing portion 503 contacts the cut end surface 505 of the optical fiber 501. When the optical fiber 501 is further pushed in, as shown in FIG. 18B, a load is applied in the circumferential direction of the coating 507. When the pressing load reaches a peak, the pressing load exceeds the coating breaking force, and FIG. As shown in FIG. As a load for removing the coating 507, an elastic restoring force at the bent portion of the optical fiber 501 is used. In this way, the coating 507 is removed by the coating removing unit 503 provided at the tip, and the bare optical fiber 511 is positioned in the optical fiber insertion hole 509.

JP 2005-345753 A

However, since the outer shape of the contact surface in the conventional coating removal unit 503 is circular, the stress (scissing force) in the direction from the center toward the outer diameter of the coating 507 is uniform, and the optical fiber having a high toughness with a certain degree of coating. Then, as shown in FIG.18 (d), the coating | cover 507 became bellows shape, the coating removal force increased, and the connection workability | operativity might be reduced.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical fiber coating removal method and coating removal that can remove the coating with a small pressing load even when using an optical fiber having a coating with high toughness. It is in providing a member and an optical connection member.

The above object of the present invention is achieved by the following configuration.
(1) An optical fiber coating removing method for removing coating from an exposed cut end surface of an optical fiber,
A first step of pressing a coating removing member having an optical fiber insertion hole for inserting a bare optical fiber of the optical fiber against a coating on a cut end surface of the optical fiber;
A second step of causing the coating to crack by pressing the coating so that the stress in the outer diameter direction is non-uniform from the contact surface with the coating removing member;
A third step of further pressing the coating removing member to cut the coating in the longitudinal direction of the optical fiber starting from the crack;
An optical fiber coating removing method comprising:

  According to this optical fiber coating removing method, when the coating removing member is pressed against the coating, the stress in the outer diameter direction from the contact surface with the coating removing portion in the cut end surface of the coating becomes non-uniform. That is, a portion where stress increases (concentrates) can be formed in the vicinity of the outer diameter in the cut end face. As a result, the pressing force is efficiently converted into the coating removal force, and a crack can be easily formed in the coating with a small pressing load.

(2) The optical fiber coating removal method of (1),
The optical fiber has a first covering layer that is an inner layer in which a coating covering at least the outer periphery of the bare optical fiber is in contact with the bare optical fiber, and a second coating layer that covers the outside of the first coating layer,
In the first step, at least a part of the tip of the coating removing member is pressed against only the first coating layer of the optical fiber, and the second step is performed.

  According to this optical fiber coating removal method, when the coating removal member is pressed against the coating, at least a part of the tip of the coating removal member always contacts only the first coating layer in the cut end surface of the coating. Thereby, it can prevent that a 2nd coating layer is compressed, a part of front-end | tip can penetrate into a 1st coating layer, a 2nd coating layer can be expanded outwardly reliably, and a coating | cover can be torn.

(3) An optical fiber coating removing member for removing the coating from the exposed cut end surface of the optical fiber,
Having an optical fiber insertion hole through which the bare optical fiber of the optical fiber is inserted, and having a coating removing portion that comes into contact with the coating of the cut end surface of the optical fiber,
The coating removal member for an optical fiber, wherein the coating removal portion has a corner on a contact surface that contacts the coating.

  According to this optical fiber coating removing member, when the contact surface comes into contact with the coating, the stress generated in the coating from the inside to the outer diameter direction becomes non-uniform due to the reaction force from the contact surface. Cracks are likely to occur at high sites.

(4) The optical fiber coating removing member of (3),
The said contact removal member is the said angle | corner which contact | abuts only the said 1st coating layer among the 1st coating layer of the inner layer which the said contact surface covers the outer periphery of a bare optical fiber, and the 2nd coating layer which covers the outer side of this 1st coating layer. An optical fiber coating removing member having a portion.

  According to this optical fiber coating removing member, at least one corner hits only the first coating layer. Thereby, a corner | angular part can be reliably approached into a 1st coating layer, a 2nd coating layer can be expanded outward, and a coating | cover can be torn.

(5) The optical fiber coating removing member of (3) or (4),
An optical fiber coating removing member, wherein an inner diameter side of the contact surface facing the optical fiber insertion hole is formed as an inclined surface inclined to guide the optical fiber to the optical fiber insertion hole.

  According to this optical fiber coating removing member, the inner diameter side of the contact surface and the optical fiber insertion hole are connected via the inclined surface. That is, the contact surface leads to the optical fiber insertion hole through an inclined surface (taper) that is tapered toward the back side. This facilitates the introduction of the bare optical fiber whose coating is removed at the contact surface into the optical fiber insertion hole. In addition, the inner diameter side of the contact surface can be made larger than the optical fiber insertion hole. Thereby, a corner | angular part with a small front-end | tip area (it is easy to approach a 1st coating layer) can be formed.

(6) The optical fiber coating removing member of any one of (3) to (5),
The optical fiber coating removing member, wherein the corner portion is formed by a protrusion provided on a contact surface of the coating removing member.

  According to this coating removal member for an optical fiber, a corner that has a small tip area can be formed by further projecting the projection that is a corner from the contact surface of the coating removal member. Accordingly, when the coating removing member is pressed against the coating, the protrusion can be easily stuck in the first coating layer, and the coating can be cut by causing the corner portion to enter the first coating layer more easily.

(7) The optical fiber coating removal member of any one of (3) to (6),
The contact surface has a length from the center of the optical fiber insertion hole to the outer end of the corner portion that is not more than half the outer diameter of the first coating layer, and the diameter of the bare optical fiber insertion side is the light. An optical fiber coating removal member characterized in that it is set larger than the inner diameter of the fiber insertion hole.

  According to this optical fiber coating removal member, when the coating removal portion is pressed against the optical fiber at the same center, the corner portion of the coating removal portion hits the inside of the outer diameter of the first coating layer. The same applies to a configuration with one corner. Further, the contact surface is set such that the diameter of the bare optical fiber insertion side is set larger than the inner diameter of the optical fiber insertion hole, so that the optical fiber insertion hole is tapered by an inclined surface (taper) tapered to the back side. It becomes easy to introduce a bare optical fiber, and a corner having a small tip area can be formed.

(8) The optical fiber coating removing member of any one of (3) to (7),
The optical fiber coating removal member, wherein the contact surface is formed in a polygonal shape.

  According to this optical fiber coating removing member, at least one side portion of the polygonal contact surface is contacted through any two points of the coating outer diameter (outer periphery), so that the coating is The stress along this side (that is, toward the outer diameter direction) can be concentrated. In addition, if the corner is arranged inward of the cut end face, stress concentrates in two corners intersecting from both directions, and more stress (cover removal force) toward the outer diameter direction is concentrated. Can do.

(9) The optical fiber coating removal member of any one of (3) to (8),
The coating removal member for an optical fiber, wherein the abutment surface is formed in an astigmatic shape with respect to the center of the optical fiber insertion hole.

  According to this optical fiber coating removal member, the contact surface formed in a trapezoidal shape having an asymmetrical shape, for example, is stressed by a specific corner portion, compared to the contact surface formed in a square shape having a symmetrical shape. Easy to concentrate.

(10) The optical fiber coating removing member of any one of (3) to (9),
The sheath removal portion is formed in a cone shape in which an outer diameter shape of at least a region close to the contact surface expands from the contact surface toward the other surface. .

  According to this optical fiber coating removal member, the region close to the contact surface (that is, the side surface of the cone shape) becomes a tapered shape that gradually expands. It can be converted into a component force in the direction in which the crack is torn, and the tearability is improved.

(11) A coating removal member for an optical fiber according to any one of (3) to (10),
The coating removal member for an optical fiber, wherein the coating removal portion is formed with an oblique tip.

  According to this optical fiber coating removing member, when the contact surface comes into contact with the coating, the reaction force from the contact surface increases at the tip of the contact surface that is cut obliquely, and the cutting resistance decreases. The coating removal force is further reduced.

(12) any one of the coating removal members of (3) to (11);
A base member having a fixing portion at the rear end portion for fixing the optical fiber while attaching the coating removing member to the front end portion;
A housing that covers the sheath removal member and the base member;
An optical connecting member comprising:

  According to this optical connection member, the optical fiber inserted into the optical connection member via the base member is covered and removed with a small pressing force (insertion force), and the rear of the cut end surface is fixed to the base member by the fixing portion. Thus, an easy optical connection to the optical fiber becomes possible.

  According to the optical fiber coating removing method according to the present invention, the coating is pressed from the contact surface with the coating removing portion so that the stress in the outer diameter direction becomes non-uniform, and the coating is cracked. Since the coating is cut in the longitudinal direction of the optical fiber from the starting point, the coating having a certain length or more can be removed with a small pressing load against the optical fiber having a coating with high toughness.

  According to the optical fiber coating removing member of the present invention, since the contact surface that contacts the coating is provided with a coating removal portion having a corner, if the contact surface contacts the coating, The stress in the outer diameter direction generated in the coating due to the force becomes non-uniform, and a crack can be easily generated at the highest stress portion. As a result, it becomes possible to cut from the crack as a starting point, and the coating removal force can be reduced.

  According to the optical connecting member of the present invention, the base member having the fixing portion for fixing the optical fiber at the rear end portion and the housing for covering the base member and the covering removing member is provided. Therefore, it is possible to connect and fix to the optical fiber with a small covering removing force, and to improve the construction workability of the optical line.

It is sectional drawing of the optical connection member which concerns on this invention. It is sectional drawing in the axis orthogonal plane of the optical fiber shown in FIG. It is a principal part expansion perspective view of the coating removal member shown in FIG. It is a front view of the coating removal part which showed the example of the shape of the contact surface by (a)-(e). It is a front view of the coating | coated removal part by which the cross groove was formed in the contact surface. It is sectional drawing by the surface containing the axis line of the coating | coated removal part by which the front-end | tip was cut diagonally. It is a front view of the contact surface and covering cutting | disconnection end surface which represented the process of the coating removal by (a)-(c). It is sectional drawing by the surface containing the coating removal part which represented the process of coating removal by (a)-(c), and the axis line of an optical fiber. It is the schematic diagram showing the condition of the stress which acts on the cut end surface of an optical fiber. (A) is the perspective view of the coating removal part which clarified the size, (b) is the enlarged front view. It is sectional drawing which cut | disconnected the coating removal part shown in FIG. 10 by the surface along an axis. (A) is a perspective view of the coating | coated removal part which made the corner part two, (b) is the enlarged front view. (A) is a front view explaining the effect | action when a coating removal part and an optical fiber contact without deviation, (b) is a front view explaining the effect | action at the time of contacting with a gap. (A) is a perspective view of the coating | coated removal part from which the corner | angular part protruded, (b) is the enlarged front view. (A) is the principal part expansion perspective view of the coating removal part shown in FIG. 14, (b) is the expansion side view. (A) is a perspective view of the coating | coated removal part in which the protrusion was provided in the corner | angular part, (b) is the principal part enlarged view. (A) is the principal part expansion perspective view of the coating removal part shown in FIG. 16, (b) is the expansion side view. It is sectional drawing by the surface containing the axis line of the optical fiber which represented the coating removal condition by the conventional optical connection member by (a)-(d).

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an optical fiber coating removal method, a coating removal member, and an optical connection member according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of an optical connection member according to the present invention.
The optical connecting member according to the present embodiment will be described by taking an optical connector 100 that can be attached to a coated optical fiber (hereinafter simply referred to as “optical fiber”) 1 at a work site as an example.
The optical connector 100 includes a ferrule 200 that is a sheath removing member, a base member 5 that has a ferrule 200 attached to the front end portion and a fixing portion 3 that fixes the optical fiber 1 at the rear end portion, and the ferrule 200 and the base member 5. It is roughly divided into a housing 7 to be covered.
In the optical connector 100, the optical fiber 1 inserted into the ferrule 200 via the base member 5 is covered and removed with a small pressing force (insertion force), and the rear of the cut end surface is fixed to the base member 5 by the fixing portion 3. Thus, an easy optical connection to the optical fiber 1 is possible.

The ferrule 200 includes a short optical fiber 9 on the distal end side (left end side in FIG. 1) and has an optical fiber insertion hole 11 that communicates with the short optical fiber 9. The optical fiber 1 inserted into the optical fiber insertion hole 11 is fixed by the fixing portion 3 with its front end face butted to the rear end face (right end face in FIG. 1) of the short optical fiber 9.
Inside the ferrule 200, which is a constituent member of the optical connector 100, is provided with a coating removal portion 15 to be described later for removing the coating 13 from the end of the optical fiber 1 by an insertion force.

  The base member 5 of the optical connector 100 has, for example, an overall rectangular prism shape, and an intermediate surface 17 is formed by cutting the upper half into a flat shape from the center to the rear (right side in FIG. 1). . A V-groove 19 for positioning the optical fiber 1 is formed in the center of the intermediate surface 17 along the insertion direction of the optical fiber 1. A lid member 25 for forming the lid 21 and the bending space 23 of the fixed portion 3 is attached to the intermediate surface 17 from above.

A ferrule mounting hole 27 is formed at the front end portion (left end portion in FIG. 1) of the base member 5, and a notch 31 opening on the upper surface of the base member 5 is provided above the ferrule mounting hole 27. Yes.
A guide capillary 33 is incorporated in the center side (right side in FIG. 1) of the ferrule mounting hole 27 via a coating removal space 29, and a space 35 is provided between the guide capillary 33 and the intermediate surface 17. It has been.

The fixing portion 3 is provided at the rear end portion of the base member 5. The fixing portion 3 has a lid 21, and the optical fiber 1 is fixed by pressing the lid 21 against the intermediate surface 17 of the base member 5 by a fixing portion clamper 37.
The V groove 19 is similarly provided at a position corresponding to the fixing portion 3 in the base member 5, and the optical fiber 1 is pressed by a lid 21 and fixed at a predetermined position (pass line). The rear portion of the fixed portion 3 and the base member 5 is accommodated in the housing 7.

  Between the fixed part 3 and the coating removal part 15, the bending space 23 which can be accommodated in the state which bent the optical fiber 1 is provided. That is, a portion of the optical fiber 1 having a coating behind the bare optical fiber 39 inserted into the ferrule 200 is accommodated while being bent in the bending space 23, and the optical fiber 1 is fixed in the fixing portion 3. An elastic biasing force toward the connection surface of the short optical fiber 9 built in the ferrule 200 is applied to the distal end surface of the bare optical fiber 39 inserted into the optical fiber insertion hole 11 of 200. Thereby, the connection state of the short optical fiber 9 and the optical fiber 1 is stably maintained.

The bending space 23 is formed by attaching a lid member 25 to an intermediate surface 17 formed by cutting out the base member 5. The cover member 25 is a block member having a substantially rectangular parallelepiped shape as a whole, and a concave portion 41 is formed along the longitudinal direction of the base member 5 from the center of the lower surface, and the inserted optical fiber 1 bends upward. The bending space 23 is formed so that it can be performed. The concave portion 41 forming the bending space 23 has a low height at the front and rear end portions and a high portion at the center portion.
The lid member 25 is sandwiched between the base member 5 and the clamper 43.

  A guide capillary 33 that restricts the radial movement of the optical fiber 1 is provided between the sheath removing portion 15 and the bending space 23. The guide capillary 33 is provided with a positioning hole 33a having an inner diameter slightly larger than the outer diameter of the optical fiber 1 so that the bent optical fiber 1 is positioned on the pass line and the tip of the optical fiber 1 is accurately positioned. It can be guided to the coating removal section 15. The distance between the front end surface 45 of the guide capillary 33 and the rear end surface 47 of the ferrule 200 that is the sheath removing unit 15 (that is, the length of the space 29) is shorter (for example, about 0.5 to 1.0 mm). Can accurately guide the bare optical fiber 39 to the optical fiber insertion hole 11 of the ferrule 200, but the space 29 needs to be large enough to accommodate the removed coating 13.

FIG. 2 is a cross-sectional view of the optical fiber shown in FIG.
The optical fiber 1 has, for example, a bare optical fiber 39 having an outer diameter d3 = 125 μm at the center, and a coating 13 having an outer diameter d1 = 250 μm is provided so as to cover the outer periphery thereof. The bare optical fiber 39 is a glass fiber having a core and one or more cladding layers, and a glass fiber having any refractive index distribution, such as a single mode fiber or a multimode fiber, is applicable.

  The coating 13 is provided in the innermost layer, and a primary 49 which is a first coating layer having an outer diameter d2 in contact with the bare optical fiber 39, and a secondary (outer coating) 51 which is a second coating layer covering the outside of the primary 49. However, the present invention is not limited to this, and it may have a configuration of one layer or two or more layers. A colored layer 53 may be provided on the outermost layer of the secondary 51. The resin constituting the coating 13 is an ultraviolet curable resin such as urethane acrylate, and physical properties such as elastic modulus are appropriately set. For example, the primary 49 in contact with the bare optical fiber 39 has a lower elastic modulus (that is, soft) than the secondary 51.

  The degree of adhesion of the primary 49 is set smaller for the bare optical fiber 39 than for the secondary 51 (bare optical fiber <secondary). That is, the coating 13 is easily peeled off from the bare optical fiber 39. Further, the Young's modulus of each member constituting the optical fiber 1 is set so that the bare optical fiber 39 of the load support body is the largest, and then the secondary 51 and the primary 49 are sequentially reduced (primary <secondary <bare). Optical fiber). Therefore, in the optical fiber 1, the coating 13 is peeled and broken through the primary 49 by pressurizing the cut end face.

3 is an enlarged perspective view of a main part of the coating removing member shown in FIG.
The ferrule 200 is a substantially cylindrical member, and an optical fiber insertion hole 11 having an inner diameter D slightly larger than the outer diameter d3 of the bare optical fiber 39 is provided along the axis G. A notch 55 (see FIG. 1) is provided near the rear part of the ferrule 200, and the optical fiber insertion hole 11 is exposed. The notch 55 is positioned below the notch 31 provided in the base member 5 when the ferrule 200 is fitted into the ferrule mounting hole 27 of the base member 5, so that the optical fiber insertion hole 11 has the notches 33 and 55. Through the outside.
The short optical fiber 9 is an uncovered bare optical fiber. The front end surface 59 is aligned with the front end surface 57 of the ferrule 200, and the rear end surface is exposed at the notch 55 and fixed to the optical fiber insertion hole 11 with an adhesive. .

  That is, since the butted connection surface between the short optical fiber 9 and the bare optical fiber 39 is exposed in the notches 31 and 55, the refractive index matching material can be easily put into the connection surface. Thereby, low loss and low reflection of the transmission destination on the connection surface are achieved. Further, when the bare optical fiber 39 is inserted into the optical fiber insertion hole 11 and pressed against the short optical fiber 9, air can escape from the cutouts 31 and 55, so that a resistance to compress air does not occur and the connection is made smoothly. It can be performed. As shown in FIG. 1, the ferrule 200 is attached to the ferrule attachment hole 27 of the base member 5, and the front portion of the ferrule 200 and the base member 5 is accommodated in the housing 7.

The ferrule 200 constitutes the coating removal portion 15 in the vicinity of the insertion opening of the optical fiber insertion hole 11 on the rear end face 47. The coating removing unit 15 works to peel and remove the coating 13 from the bare optical fiber 39 by pressing the cut end face of the optical fiber 1.
The optical fiber insertion hole 11 can be, for example, a round hole, a square hole, a regular polygonal hole, or a V-shaped groove. Here, a case of a round hole will be described as a preferred example. The inner diameter D of the optical fiber insertion hole 11 is larger than the diameter d3 of the bare optical fiber 39 of the optical fiber 1 and smaller than the outer diameter d1 of the coating 13. Thus, when the cut end surface of the optical fiber 1 is pressed around the optical fiber insertion hole 11, the contact surface 61 around the optical fiber insertion hole 11 contacts the cut end surface of the coating 13, and the bare optical fiber 39 includes It will not contact.

The coating removal unit 15 has a corner portion between the contact surface 61 and the coating 13. When the contact surface 61 comes into contact with the coating 13, a reaction force from the contact surface 61 is generated on the coating 13. Stress is generated in the coating 13 by this reaction force. Since the contact surface 61 has a corner, the stress generated in the coating 13 from the inside toward the outside diameter becomes non-uniform, and a crack is likely to occur at the highest stress portion.
In addition, by making the tip of the sheath removing portion 15 slant, the tip portion of the sheath removing portion 15 is first brought into contact with the tip, and the stress generated in the sheath 13 from the inside toward the outside diameter becomes non-uniform. You may do it.

FIG. 4 is a front view of the coating removal unit shown in (a) to (e) as examples of the shape of the contact surface.
The contact surface 61 is preferably formed in a polygonal shape. In the present embodiment, as shown in FIG. 3, the contact surface 61 is formed in a rhombus having the same length on all four sides. Of course, as shown to Fig.4 (a), the square which rotated the same rhombus 45 degree | times may be sufficient. In addition, various shapes can be exemplified as the shape having corners.

That is, as shown in FIG. 4B, a rectangular contact surface 61A can be formed. As shown in the figure, the corner 63 of the contact surface 61A may be located outside the outer diameter d1 of the covering 13. At least one side 65 of the polygonal contact surface 61A is contacted through any two points a and b of the outer diameter (outer periphery) d1 of the coating, so that the coating 13 is brought into contact with the side 65. The stress along (ie, toward the outer diameter direction) can be concentrated. As shown in FIG. 4 (a), if the corner 63 is disposed inward of the cut end face, stress is bi-directionally applied to the corner 63 of the intersecting two sides 67 and 67 (FIG. 4 (a)). It is possible to concentrate more stress (coating removal force) toward the outer diameter direction, concentrated from the arrow direction in the middle.
The corner portion is preferably formed by two straight lines and has a sharp structure, but it is sufficient that the stress is non-uniform even if there is a slightly curved portion.

  Further, the abutting surface 61 may be formed asymmetry with respect to the axis G. The astigmatic shape means a shape that does not overlap the contact surface 61 before rotation when the contact surface 61 is rotated 180 degrees around the axis G. For example, the trapezoidal contact surface 61B shown in FIG. The contact surface 61B formed in a trapezoidal shape having an asymmetric shape can easily concentrate stress on the specific corner portion 63, compared to the contact surface 61 formed in a square shape having a symmetrical shape.

  In addition, the abutting surface 61 is composed of a hexagonal abutting surface 61C shown in FIG. 4 (d), an octagonal abutting surface, or only one corner 63 as shown in FIG. 4 (e). It may be a contact surface 61D having In addition, although illustration is abbreviate | omitted, the contact surface 61 can also be made into a triangle. In this case, it is also assumed that the corner 63 is positioned outside the outer diameter d1 of the covering 13, but as described above, at least one side part is any two points a of the covering outer diameter (outer periphery) d1, By abutting through b, stress along this side can be concentrated on the covering 13.

  It is preferable that the outer diameter shape of the area | region near the contact surface 61 is formed in the cone shape which the coating removal part 15 expands toward the other surface from the contact surface 61 at least. As shown in FIG. 3, the coating removing unit 15 of the present embodiment is formed in a substantially quadrangular pyramid shape in which the contact surface 61 is an equilateral rhombus. By adopting such a substantially quadrangular pyramid shape, a region close to the contact surface 61 (that is, the cone-shaped side surface 71) has a tapered shape that gradually expands. By setting it as such a taper shape, the reaction force can be converted into the component force of the direction in which a crack is torn by the press of the contact surface 61, and a tearability can be improved more.

In the ferrule 200, an insertion space 73 for the optical fiber 1 is formed in the rear end face 47, and a substantially pyramid-shaped coating removal portion 15 is provided so as to protrude coaxially on the inside thereof.
In the insertion space 73 around the coating removing portion 15, the stripped coating 13 is accommodated together with the space 29.

FIG. 5 is a front view of the coating removing portion in which a cross groove is formed on the contact surface.
In addition, the contact surface 61 may be formed with a cross-shaped cutout 75 as shown in FIG. By providing the notch 75, it is possible to improve the tearability by using the edge portion 75a as a blade portion. Moreover, the corner | angular part 63 can also be increased.

FIG. 6 is a cross-sectional view of the surface including the axis of the coating removal portion whose tip is cut obliquely.
Furthermore, the coating removal part 15 may be cut obliquely at the tip formed in a cone shape. According to such a contact surface 61E cut obliquely, when the contact surface 61E comes into contact with the coating 13, the front end portion 77 of the contact surface 61E cut obliquely by the reaction force from the contact surface 61E. And the cutting resistance is reduced, and the coating removal force is further reduced.

Next, a procedure for attaching the optical connector 100 to the optical fiber 1 will be described.
FIG. 7 is a front view of the abutting surface and the coating cut end surface in which the coating removal process is represented by (a) to (c), and FIG. 8 is a coating removal unit in which the coating removal process is represented by (a) to (c). FIG. 9 is a schematic view showing the state of stress acting on the cut end face of the optical fiber.
First, the lid member 25 is clamped by the clamper 43 to form a passage for inserting the optical fiber 1 including the V-groove 19 between the lid member 25 and the intermediate surface 17 of the base member 5.

  Next, the optical fiber 1 is inserted into the guide capillary 33 and positioned in the radial direction, and the cut end face of the optical fiber 1 is removed from the ferrule 200 as shown in FIGS. 7 (a) and 8 (a). Press against part 15. In addition, in order to bend and bend the straight optical fiber 1, a force of about 100 gf is required. When the optical fiber 1 is pressed against the coating removing portion 15, the coating 13 is compressed in the direction of the axis G, and stress along the side portion 65 of the contact surface 61 is concentrated on the coating 13. If the corner portion 63 of the contact surface 61 is disposed inward of the cut end surface as in the present embodiment, stress is bidirectionally applied to the corner portions 63 of the intersecting two side portions 67 and 67 (in FIG. 9). Large stress (covering force F (f + f)) concentrated in the outer diameter direction.

  When this coating removal force F is generated, as shown in FIGS. 7B and 8B, the primary 49 is broken and peeled off from the bare optical fiber 39, and then the part corresponding to the corner 63 of the secondary 51 A crack 79 is formed in the surface.

When the optical fiber 1 is further pressed against the coating removing portion 15, a crack 79 is a starting point, and the coating 13 is cut off by the tapered side surfaces 71 and 71 as shown in FIGS. 7 (c) and 8 (c). ) Goes on.
In the coating removing unit 15, the ridge line where the side surfaces 71, 71 act as the knife edge 81 (see FIG. 3), and the coating 13 can be easily cut.

  More specifically, in the conventional cone-shaped coating removal portion, the coating removal load that was required for Sample A at 314 gf is 111 gf in the quadrangular pyramid-shaped coating removal portion 15, which is about 1/3 of the load reduction. Was confirmed. Also in sample B, it was confirmed that the coating removal load that required 120 gf in the conventional cone-shaped coating removing portion was reduced to 70 gf in the quadrangular pyramid-shaped coating removing portion 15.

In this way, the coating 13 is peeled off, and only the bare optical fiber 39 is inserted into the optical fiber insertion hole 11 of the ferrule 200, and the peeled coating 13 is accommodated in the spaces 29 and 73. Next, the lid member 25 is fitted to the base member 5 to form the bending space 23. In this state, a bending portion 83 of the optical fiber 1 is formed in the bending space 23. Thereafter, the lid 21 of the fixing unit 3 is completely clamped by the fixing unit clamper 37 to fix the optical fiber 1.
If the lid member 25 and the lid 21 of the fixing portion 3 are integrated, the optical fiber 1 can be fixed at the fixing portion 3 at the same time as the bending portion 83 is formed in the bending space 23.

  In this coating removal method of the optical fiber 1, when the ferrule 200 is pressed against the coating 13, the stress in the outer diameter direction from the center of the optical fiber insertion hole 11 in the cut end surface of the coating 13 becomes non-uniform. That is, a portion where stress increases (concentrates) can be formed in the vicinity of the outer diameter in the cut end face. As a result, the pressing force is efficiently converted into the coating removal force, and a crack can be easily formed in the coating with a small pressing load.

  Therefore, according to the coating removal method of the optical fiber 1 described above, the coating 13 is pressed from the contact surface 61 so that the stress in the outer diameter direction becomes nonuniform, and the coating 13 is caused to have a crack 79, and the crack is generated. Since the coating 13 is cut in the longitudinal direction of the optical fiber starting from 79, the coating 13 having a certain length or more can be removed with a small pressing load against the optical fiber 1 having the coating 13 having high toughness.

  Further, according to the ferrule 200 of the optical connector 100, since the covering removal portion 15 having the corners is provided, when the contact surface 61 comes into contact with the coating 13, the reaction force from the contact surface 61 causes the coating 13 to generate. The stress toward the outer diameter direction becomes non-uniform, and the crack 79 can be easily generated at the highest stress portion. As a result, it is possible to cut the crack 79 as a starting point and reduce the covering removal force.

  Further, according to the optical connector 100, the base member 5 having the ferrule 200 attached to the front end portion and the fixing portion 3 for fixing the optical fiber 1 at the rear end portion, and the housing 7 covering the ferrule 200 and the base member 5 are provided. Since it is provided, it can be connected and fixed to the optical fiber 1 with a small coating removal force, and the construction workability of the optical line can be improved.

Next, the coating removal unit will be described in more detail.
As described above, by providing the corner portion 63 at the tip of the coating removing portion 15, the load generated when the optical fiber 1 is pressed is concentrated on the corner portion 63, and the coating 13 is easily broken. However, the optical fiber 1 is composed of a bare optical fiber 39, a primary 49, a secondary 51, and a colored layer 53 (see FIG. 2), and it is important which layer the tip of the coating removal portion 15 is pressed against.
For example, when the contact surface 61 is a 0.175 mm square pyramid, the distance between the diagonal corners 63 is 0.247 mm, which is substantially the same as the diameter d1 of the optical fiber 1 (the diameter of the colored layer 53). Therefore, the corner 63 comes into contact with the secondary 51 having a Young's modulus about 1000 times that of the primary 49 and the colored layer 53 that is harder than that.
When the coating removing unit 15 is pressed against these hard layers to remove the coating, the coating 13 is compressed and broken, and in some cases, the coating cannot be broken and the bare optical fiber 39 may be damaged. Having the corner portion 63 in the coating removal portion 15 has the advantage of concentrating the load and is effective for coating removal, but depending on the size of the coating removal portion 15, the effect is not sufficiently exhibited (conversely, it becomes a disadvantage). there is a possibility.

For this reason, it is preferable to clarify the size of the covering removing unit 15 so that the corner 63 is stuck only in the primary 49.
FIG. 10 (a) is a perspective view of the covering removal portion whose size is clarified, and FIG. 10 (b) is an enlarged front view thereof.
In the covering removal portion 15A whose size has been clarified, the coaxial optical fiber insertion hole 11 is formed in the conical removal portion main body 91, and the top portion thereof serves as the contact surface 61. The removal unit main body 91 may be a pyramid shown in FIG. 15 A of coating | coated removal parts are primary 49 out of the 1st coating layer (primary 49) of the inner layer which covers the outer periphery of the bare optical fiber 39 shown in FIG. The contact surface 61 has a corner portion 63 </ b> A that contacts only with the contact surface 61. In the illustrated example, four corners 63A are formed, but the number of corners 63A may be an arbitrary number of one or more.

FIG. 11 is a cross-sectional view of the coating removal portion shown in FIG. 10 cut along a plane along the axis, FIG. 12 (a) is a perspective view of the coating removal portion having two corners, and (b) is an enlarged front view thereof. is there.
The contact surface 61 has a distance R from the center 93 of the optical fiber insertion hole 11 to the corner 63A that is less than half the outer diameter d2 of the primary 49 shown in FIG. 2 and the insertion side of the bare optical fiber 39. Is set to be larger than the inner diameter d5 of the optical fiber insertion hole 11.

Specifically, the following dimension examples can be used.
In the optical fiber 1, when the thickness of the colored layer 53 is taken into account, the outer diameter of the colored layer 53, that is, the outer diameter d1 of the optical fiber 1 shown in FIG. 2 is 250 μm, and the outer diameter of the secondary 51 is 245 μm. The outer diameter d2 of the primary 49 is approximately 200 μm, and the outer diameter d3 of the bare optical fiber 39 is 125 μm. On the other hand, the cover removing portion 15A has a diagonal length (2 × R) of 200 μm which is equal to the diameter d2 of the primary 49, and an inner diameter d4 which faces the optical fiber insertion hole 11 of the contact surface 61 is 160 to 170 μm. The inner diameter d5 of the optical fiber insertion hole 11 is 126 μm. Thereby, the above R <d2 / 2 and d4> d5 are satisfied.

  As shown in FIG. 12, even if the contact surface 61 has two corners 63A, the distance R from the center 93 of the optical fiber insertion hole 11 to the corner 63A is the outer diameter d2 of the primary 49. The diameter d4 on the insertion side of the bare optical fiber 39 is set larger than the inner diameter d5 of the optical fiber insertion hole 11. In addition, even when the number of corner portions 63A is one, three, or four or more, the magnitude relationship among the distance R, the diameter d2, the diameter d4, and the diameter d5 is the same as described above. Further, the corner portion 63A is not formed diagonally (symmetric), but it is effective in some cases to form it asymmetrically.

  When the sheath removing portion 15A is pressed against the optical fiber 1 at the same center, the corner portion 63A hits the inside of the outer diameter d2 of the primary 49. That is, it deviates from the outer diameter d <b> 2 of the primary 49 and does not hit the secondary 51 or the colored layer 53. The same applies to a configuration with one corner 63A.

Further, the contact surface 61 has an inclined surface (taper) 95 tapered toward the back side by setting the diameter d4 on the insertion side of the bare optical fiber 39 to be larger than the inner diameter d5 of the optical fiber insertion hole 11. To the optical fiber insertion hole 11. By forming the inclined surface 95, the bare optical fiber 39 can be easily introduced and the contact surface 61 having a small tip area can be formed. Thereby, the load applied per unit area can be increased, and the corner portion 63A that can easily enter the primary 49 can be formed.
As described above, in the covering removal unit 15A, the corner 63A hits only the primary 49 and does not come out of the primary 49 and hit the secondary 51. Therefore, the corner portion 63A can surely enter the primary 49, and the secondary 51 can be expanded outward.

Next, the operation of the coating removal unit shown in FIG. 10 will be described.
FIG. 13A is a front view for explaining the operation when the coating removal portion and the optical fiber are in the same center and contacted without displacement, and FIG. 13B is a front view for explaining the operation when contacted with displacement. It is.
The behavior of the coating removal in the coating removal unit 15A is characterized in that the secondary 51 and the colored layer 53 are expanded from the primary 49 toward the outer side and are torn. By setting the distance of the diagonal corner 63A to a length (200 μm) substantially equal to that of the primary 49, contact with the secondary 51 and the colored layer 53 can be prevented as shown in FIG. Further, even if the coating removal portion 15A and the optical fiber 1 are misaligned, as shown in FIG. 13B, at least one corner 63A is in contact with only the primary 49.

  Thus, in the coating removal method for the optical fiber 1 using the coating removal unit 15A, ideal coating removal is performed. In ideal coating removal, at least a part of the tip of the coating removal portion 15 </ b> A is pressed only against the primary 49. When the contact surface 61 of the coating removing portion 15A is pressed against only the primary 49, the secondary 51 and the colored layer 53 expand outward as the contact surface 61 enters the primary 49. As described above, stress acts on the corner portion 63A of the intersecting two side portions 67 and 67 from both directions (in the direction of the arrow in FIG. 13), and a large stress (cover removal force F (f + f)) in the outer diameter direction. Concentrate. As a result, the secondary 51 and the colored layer 53 are cracked, and the coating 13 is removed.

  In addition, as shown in FIG.13 (b), when position shift has arisen in 15 A of coating removal parts and the optical fiber 1, a part of corner | angular part 63A contact | abuts to the secondary 51 and the colored layer 53, and the said corner | angular part , The hard secondary 51 and the colored layer 53 are compressed, and there is a case where a large stress in the outer diameter direction is not generated. However, if at least one portion of the corner portion 63A is pressed against only the primary 49, at least one portion of the secondary 51 and the colored layer 53 is expanded in the outer diameter direction, a crack is generated, and the covering 13 can be cut. Become.

  If the size of the coating removal portion is not clarified, there is a risk that unstable coating removal may occur in addition to the ideal coating removal described above. That is, when the tips of the corner portions 63 are all in contact with the secondary 51 and the colored layer 53 and the contact surface 61 is pressed, the hard secondary 51 and the colored layer 53 are compressed. In some cases, the coating can be removed by compressive failure. However, if the compressive failure cannot be achieved, as shown in FIG. 18 (d), the coating 507 has a bellows shape, and the coating removal force increases. Sometimes.

  As a result of producing prototypes and comparing optical fiber damage occurrence rates, when corners are pressed against primary 49, secondary 51, and colored layer 53, 9 out of 100 prototypes are damaged by optical fiber. There has occurred. On the other hand, when the corner was pressed only against the primary 49, optical fiber damage occurred in three of the 100 prototypes. As a result, it was confirmed that the optical fiber damage occurrence rate can be improved from 9% to 3% by clarifying the size.

14A is a perspective view of the covering removal portion with the corners protruding, FIG. 14B is an enlarged front view thereof, FIG. 15A is an enlarged perspective view of the main portion of the covering removal portion shown in FIG. ) Is an enlarged side view thereof.
In the covering removal unit 15A, the contact surface 61 may be three-dimensionally formed. In the sheath removing portion 15B shown in FIGS. 14 and 15, the arc portion between the corner portions 63 </ b> B on the contact surface 61 is a concave curved surface 97. As shown in FIG. 15, the concave curved surface 97 has an outer diameter edge 97b protruding from an inner diameter edge 97a. The adjacent concave curved surface 97 forms an edge 99 at the corner 63B. In the corner portion 63 </ b> B, the apexes of the two adjacent triangular side surfaces 101 on the outside serve as the tip point 103 of the edge 99. That is, the corner 63 </ b> B has the tip 103 protruding most on the contact surface 61. Since the contact surface of the sheath removing member is formed in a three-dimensional manner and the corner portion protrudes, a corner portion having a small contact area can be formed. Thereby, when the covering removing member 15 </ b> A is pressed against the covering, the corner portion 63 can be made to enter the primary 49 more easily.
Therefore, according to the sheath removing portion 15B, when the sheath removing portion 15B is pressed against the sheath 13, the tip point 103 of the protruding corner portion 63B is stuck into the primary 49, and the corner portion 63B is more easily entered into the primary 49. be able to.

The corner 63A may be a protrusion provided on the contact surface 61. 16 (a) is a perspective view of the covering removal portion in which the protrusion is provided on the contact surface 61, FIG. 16 (b) is an enlarged view of a main portion thereof, and FIG. 17 (a) is a main portion of the covering removal portion shown in FIG. An enlarged perspective view, (b) is an enlarged side view thereof.
The covering removal portion 15 </ b> A may have protrusions protruding from the respective contact surfaces 61. In the covering removal portion 15C shown in FIGS. 16 and 17, for example, a triangular prism-shaped protrusion 105 protrudes from the contact surface 61. In addition to this, the shape of the protrusion 105 may be a columnar shape, a quadrangular prism shape, a conical / pyramidal shape, or the like.
According to the sheath removing portion 15C, when the sheath removing portion 15C is pressed against the sheath 13, the protrusion 105 can be easily stuck in the primary 49 and can be more easily entered into the primary 49.

  Therefore, according to the ferrule 200 in which the coating removal portion 15A having a clarified size is formed, when the coating removal portion 15A is pressed against the coating 13, at least one of the tip corners 63A of the coating removal portion 15A is covered with the coating 13. Only the primary 49 in the cut end face always comes into contact. Thereby, the secondary 51 and the colored layer 53 can be prevented from being compressed, the corner portion 63A can enter the primary 49, the secondary 51 and the colored layer 53 can be surely expanded outward, and the coating 13 can be cut off. it can.

DESCRIPTION OF SYMBOLS 1 Optical fiber 3 Fixing part 5 Base member 7 Housing 11 Optical fiber insertion hole 13 Cover | cover 15 Cover removal part 39 Bare optical fiber 49 Primary (1st coating layer)
51 secondary (second coating layer)
61 Contact surface 63 Corner portion 63A Side surface of at least a portion of the tip of the covering removal member 71 Side surface (region close to the contact surface)
79 Crack 93 Center of optical fiber insertion hole 95 Inclined surface 100 Optical connector (optical connection member)
105 Protrusion 200 Ferrule (Coating removal member)
G axis (center of optical fiber insertion hole)
d2 Outer diameter dimension of the first coating layer d4 Diameter on the insertion side of the bare optical fiber

Claims (8)

An optical fiber coating removing member for removing the coating from the exposed cut end surface of the optical fiber ,
Having an optical fiber insertion hole through which the bare optical fiber of the optical fiber is inserted, and having a coating removing portion including a contact surface that contacts the coating of the cut end surface of the optical fiber,
The contact surface of the coating removal portion is a circular shape whose inner periphery communicates with the optical fiber insertion hole and whose outer periphery includes a corner portion,
The covering removal portion is formed in a conical shape in which an outer diameter shape of at least a region close to the contact surface expands from the contact surface toward a surface facing the contact surface. Optical fiber coating removal member . The optical fiber coating removing member according to claim 1,
In the covering removal portion, the contact surface contacts only the first covering layer among the first covering layer of the inner layer covering the outer periphery of the bare optical fiber and the second covering layer covering the outside of the first covering layer. An optical fiber coating removing member having the corner portion . An optical fiber coating removing member according to claim 1 or 2 ,
The light having the inclined surface inclined to guide the optical fiber to the optical fiber insertion hole between the inner periphery of the contact surface and the optical fiber insertion hole. Fiber sheath removal member. It is the coating removal member of the optical fiber according to any one of claims 1 to 3 ,
The contact surface has a length from the center of the optical fiber insertion hole to the outer end of the corner portion that is not more than half of the outer diameter of the first coating layer, and on the insertion side of the bare optical fiber. An optical fiber coating removing member, wherein the diameter is set larger than the inner diameter of the optical fiber insertion hole . An optical fiber coating removing member according to any one of claims 1 to 4 ,
The optical fiber coating removal member , wherein the contact surface is formed in a polygonal shape . An optical fiber coating removing member according to any one of claims 1 to 5 ,
The coating removal member for an optical fiber, wherein the abutment surface is formed in an astigmatic shape with respect to the center of the optical fiber insertion hole . An optical fiber coating removing member according to any one of claims 1 to 6 ,
The coating removal member for an optical fiber, wherein the contact surface of the coating removal portion is formed obliquely with respect to a plane perpendicular to the axial direction of the optical fiber insertion hole . The sheath removal member according to any one of claims 1 to 7,
  A base member having a fixing portion at the rear end portion for fixing the optical fiber while attaching the coating removing member to the front end portion;
  A housing that covers the sheath removal member and the base member;
  An optical connecting member comprising:

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