JP2010231151A - Method of manufacturing ferrule and ferrule with refractive index adjustment film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a ferrule which is properly processed and uses the minimum amount of expensive materials, to provide a ferrule with a refractive index adjustment film, and to obtain the ferrule with a refractive index adjustment film at low cost. <P>SOLUTION: An ultraviolet ray curing type resin is stuck on one end part of the ferrule, the ultraviolet-curing type resin is hardened, by having the ultraviolet rays for forming a soft material layer irradiated thereon; another ultraviolet-curing type resin is stuck on the soft material layer; the other ultraviolet-curing type resin is hardened, by having ultraviolet rays for forming a hard material layer irradiated thereon, thus the refractive index adjustment film constituted of the two layers is formed on one end part of the ferrule. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a ferrule manufacturing method in which a refractive index adjusting film having two layers is formed at one end, and a ferrule with a refractive index adjusting film.

  In order to connect optical fibers, physical connection is generally performed in which optical fibers or ferrules into which optical fibers are inserted are abutted. Since air enters between the end portions of the optical fibers that are abutted and Fresnel reflection is increased at the connection end face, there is a problem that connection loss increases. Accordingly, an optical connector for optically connecting a sheet-like adhesive material composed of a single layer (for example, see Patent Document 1) as a connecting member having refractive index matching between a pair of ferrules to which optical fibers are fixed. It has been known.

  In this optical connector, the optical fiber is cut and inserted into a ferrule without polishing the end face. At this time, since the end face is not polished, minute irregularities exist. Since the sheet-like adhesive material is provided on the front end surface of the ferrule in which the optical fiber holding hole is opened, minute irregularities on the end surface are absorbed. Therefore, according to the optical connector provided with this sheet-like adhesive material, the optical fibers can be brought into close contact with each other with a simple structure. In addition, the optical characteristics were stable regardless of whether or not the end face of the optical fiber was polished, the optical connector could be easily attached and detached, and improvement in workability could be expected.

JP 2005-351998 A

However, in an optical connector that optically connects a sheet-like adhesive material between a pair of ferrules, for example, the sheet-like adhesive material is composed of a soft material layer and a hard material layer in order to reduce the pressure at the time of connector connection. Although a two-layer refractive index adjusting sheet may be used, it is necessary to have a specific refractive index, so that a member to be used becomes very expensive. At the time of manufacturing such a two-layer refractive index adjusting sheet, a fixed-size refractive index sheet having a two-layer structure was produced, and the sheet was punched out so as to have a fixed shape (small round shape). There was a problem that a large amount of the portion remained, and the production cost of the two-layer refractive index adjusting sheet increased accordingly. In addition, since the refractive index adjusting sheet that has been finely punched must be aligned with the optical fiber holding hole and attached to the tip of the ferrule, there is a problem that workability is poor and work cost is increased.
The present invention has been made in view of the above situation, and provides a ferrule manufacturing method and a ferrule with a refractive index adjustment film that have a high processing rate and a high utilization rate of expensive materials, and thus sufficiently exhibit the function as an optical connector. And it aims at obtaining the ferrule with a refractive index adjustment film | membrane cheaply.

The above object of the present invention is achieved by the following configuration.
(1) Adhere UV curable resin to one end of ferrule,
The ultraviolet curable resin is irradiated with ultraviolet rays and cured to form a soft material layer,
Adhering another UV curable resin with a large Young's modulus after curing on the soft material layer,
A ferrule manufacturing method comprising: forming a hard material layer by irradiating an ultraviolet ray to the other ultraviolet curable resin to form a hard material layer, and forming a refractive index adjusting film having two layers at one end of the ferrule.

  According to this ferrule manufacturing method, the ultraviolet curable resin attached to one end of the ferrule is cured by irradiation with ultraviolet rays to form a soft material layer and a hard material layer, and a refractive index adjustment sheet is separately attached to the ferrule tip portion. There is no need. This eliminates the need for expensive refractive index adjustment sheets (hard materials) and work with poor processability.

(2) The ferrule manufacturing method of (1),
When forming the soft material layer, the ferrule tip is immersed in an ultraviolet curable resin solution for the soft material layer, and the ultraviolet curable resin for the soft material layer is adhered to a part and one end of the ferrule. ,
The other end of the ferrule is sealed with a cap, and the ferrule is taken out from the ultraviolet curable resin liquid for the soft material layer,
Irradiate ultraviolet rays to cure the ultraviolet curable resin for the soft material layer,
An ultraviolet curable resin for a hard material layer is attached on the soft material layer,
A ferrule manufacturing method characterized by irradiating ultraviolet rays to cure the ultraviolet curable resin for the hard material layer.

  According to this ferrule manufacturing method, when the ferrule tip is immersed in the ultraviolet curable resin liquid for the soft material layer, the ultraviolet curable resin liquid for the soft material layer is opened in the inside (optical fiber holding hole) opened in the ferrule tip. Is sucked up by capillary action. By sealing the other end of the ferrule with a cap, the ultraviolet curable resin liquid for the soft material layer sucked inside is prevented from falling. The soft material layer is formed of the ultraviolet curable resin for the soft material layer which is cured by irradiating the ferrule tip portion with the ultraviolet light in a state where it is taken out from the ultraviolet curable resin liquid for the soft material layer. The ferrule is erected so that the soft material layer is on the upper side, and the hard material layer is laminated by irradiating the ultraviolet curable resin for the hard material layer dropped onto the base with the soft material layer, and the two layers A refractive index adjusting film is formed.

(3) The ferrule manufacturing method of (1) or (2),
A ferrule manufacturing method, wherein the soft material layer is cured by irradiating ultraviolet rays from below the ferrule that is erected with the one end portion as a lower end.

(4) The ferrule manufacturing method of (2),
A method for producing a ferrule, comprising: using a transparent member for the cap to irradiate ultraviolet light from above the ferrule that is erected with the one end portion as an upper end, and curing the soft material layer.

(5) A ferrule manufactured by any one of the ferrule manufacturing methods of (1) to (4),
The ferrule with a refractive index adjusting film, wherein the soft material layer enters a part of the inside of the ferrule.

  According to the ferrule with a refractive index adjusting film, the outer peripheral surface of the soft material layer adheres to the inner peripheral surface of the optical fiber holding hole of the ferrule, and the bonding strength of the soft material layer to the ferrule increases. Further, the thickness of the soft material layer can be increased without causing the soft material layer to protrude from the tip end surface of the ferrule, and the buffering effect of the soft material layer can be increased.

  According to the ferrule manufacturing method according to the present invention, it is not necessary to separately attach a refractive index adjusting sheet to the ferrule tip portion. As a result, the processability of the optical connector can be improved and the processing time can be shortened. In addition, the material utilization rate increases and the product cost can be greatly reduced.

  According to the ferrule with a refractive index adjusting film according to the present invention, since the soft material layer has entered a part of the inside of the ferrule, the bonding strength of the soft material layer to the ferrule can be increased, and the soft material layer The buffer effect can be increased.

It is a flowchart showing the procedure of the ferrule manufacturing method which concerns on this invention. FIG. 2 is a manufacturing process diagram schematically showing the procedure of the previous stage shown in FIG. 1 by (a), (b), (c), (d), or (e). It is a manufacturing process figure which represented the procedure of the latter part shown in Drawing 1 typically by (e) (f) (g) (h). It is a principal part expanded sectional view of the refractive index adjustment film | membrane vicinity showing an example in the case of connecting the single core optical fiber of the ferrule manufactured with the ferrule manufacturing method which concerns on this invention. It is sectional drawing of an optical connector provided with the ferrule in which the refractive index adjustment film | membrane was formed.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of a ferrule manufacturing method according to the invention will be described with reference to the drawings.
FIG. 1 is a flowchart showing a procedure of a ferrule manufacturing method according to the present invention, and FIG. 2 is a manufacturing process diagram schematically showing the previous steps shown in FIG. 1 by (a), (b), (c), and (d), FIG. 3 is a manufacturing process diagram schematically showing the subsequent steps shown in FIG. 1 by (e), (f), (g), and (h).
The ferrule manufacturing method according to the present embodiment will be described, for example, with respect to a method for manufacturing a ferrule with a refractive index adjustment film attached to an on-site optical connector. This manufacturing method is characterized in that a refractive index adjusting film comprising two layers is formed on a ferrule.

  In order to manufacture a ferrule with a refractive index adjusting film composed of two layers, first, a predetermined ferrule is prepared. In this embodiment, the ferrule has an outer diameter of 1.5 to 2.0 mm, and the optical fiber holding hole has an inner diameter of 0.13 mm. An ultraviolet curable resin is attached to one end of the ferrule (portion connected to another optical connector). More specifically, as shown in the process S1 of FIG. 1 and FIG. 2A, the soft material layer is formed at a constant immersion length A for a certain period of time in order to form the soft material layer. In the ultraviolet curable resin liquid 15 for use, it is immersed in the attitude | position which stood up in the perpendicular direction. Thereby, the ultraviolet curable resin 15 for soft material layers is made to adhere to the inside of the ferrule 11 (optical fiber holding hole 13) and one end part 11a.

  By immersing one end portion 11a of the ferrule 11 in the optical fiber holding hole 13, the ultraviolet curable resin 15 for the soft material layer becomes higher than the liquid surface B due to a capillary phenomenon, and a certain amount is sucked up. As a result, a necessary amount of the ultraviolet curable resin 15 for the soft material layer is placed inside the ferrule.

  As the ultraviolet curable resin 15 for the soft material layer, for example, an acrylic resin is used, and the viscosity thereof is preferably in the range of 10 to 1000 mPa · S (a degree that increases due to capillary action). The immersion length A of the ferrule 11 is controlled to be 40 μm or less, for example. Further, the immersion time is about several seconds to several tens of minutes, and the final immersion time is mainly determined by the viscosity of the ultraviolet curable resin agent, the wettability inside the ferrule, the tip / internal shape of the ferrule, and the material of the ferrule 11.

  Next, as shown in process S2 of FIG. 1 and FIG. 2 (b), after the ultraviolet curable resin 15 for the soft material layer is adhered inside the ferrule for a certain time, the other end portion (ferrule rear end portion) 11b of the ferrule Is hermetically sealed with a cap 17, and the ferrule 11 is taken out from the ultraviolet curable resin liquid 15 for the soft material layer as shown in the process S <b> 3 of FIG. 1 and FIG. Since the other end portion 11 b is sealed with the cap 17, it flows out of the optical fiber holding hole 13 due to the balance between the atmospheric pressure, the pressure inside the ferrule, and the surface tension and gravity of the UV curable resin 15 for the soft material layer. Disappear.

  Next, as shown in the process S4 of FIG. 1 and FIG. 2D, the ferrule 11 pulled up from the ultraviolet curable resin liquid 15 for the soft material layer has the ultraviolet curable resin 15 for the soft material layer contained therein. In this state, the ultraviolet ray 19 is irradiated. Thereby, the ultraviolet curable resin 15 for soft material layers adhering to the one end part 11a is hardened.

  The ultraviolet ray 19 is irradiated with a light source 16 from below the raised ferrule 11 with the one end portion 11a of the ferrule 11 as a lower end, as shown in the left diagram of FIG. The resin 15 is cured.

  Further, as shown in the example of FIG. 2 (e), the ultraviolet ray 19 is irradiated from above the ferrule 11 that is erected with the one end portion 11a as the upper end to cure the ultraviolet curable resin 15 for the soft material layer. May be. In both the case of FIG. 2D and the case of FIG. 2E, the soft material layer 21 is cured and contracted by contraction when the resin is cured.

  Thereby, as shown in FIG.3 (e), the soft material layer 21 is formed. A commercially available spot illuminator or the like can be used as the light source 16 for the irradiation of the ultraviolet rays 19. The curing time is preferably about several seconds to several minutes. The cap 17 is not removed during UV curing. This is because the soft material layer ultraviolet curable resin 15 may flow out of the ferrule 11 when it is not cured. The length L1 of the soft material layer 21 inside the optical fiber holding hole 13 after UV curing is generally 20 to 100 μm, and more preferably 20 to 40 μm.

  Later, when the optical fiber is inserted into the ferrule, the soft material layer is pushed and flattened by the optical fiber. Therefore, an acrylic resin having a refractive index of about 1.44 to 1.48 is used as the UV adhesive soft material. It is preferable to use a photopolymerization type resin composition as a base.

  As shown in FIG. 3E, the ferrule 11 on which the soft material layer 21 is formed is erected with the one end portion 11a at the upper end in preparation for the next step of forming the hard material layer. When the ultraviolet ray 19 is irradiated, if upside down is performed in advance as in the example of FIG.

  Before entering the hard material layer forming step, the excess resin 23 attached around the one end portion 11a may be removed. The resin 23 may be removed before curing. Since a hard material layer to be described later is formed on the distal end surface 25 of the one end portion 11a, the distal end surface 25 is preferably as smooth as possible.

  Next, as shown in process S5 of FIG. 1 and FIG. 3G, the ultraviolet curable resin 27 for the hard material layer, which is another ultraviolet curable resin, is attached on the soft material layer 21. For example, the ultraviolet curable resin 27 for the hard material layer is dropped from the dropping nozzle 29. The ultraviolet curable resin 27 for the hard material layer can be obtained by mixing a urethane acrylate resin (for adjusting the crosslinking density), a fluorinated acrylate resin (for reducing the refractive index), and a silicone resin. The ultraviolet curable resin 27 for hard material layer is dropped into the recess 21a of the ultraviolet curable resin 15 for soft material layer so as to have a thickness of 15 to 40 μm.

  In the present embodiment, the UV curable resin 27 for the hard material layer is attached by dropping from the dropping nozzle 29. In addition, the attachment is performed by applying with a brush, printing with a squeegee, or printing by an inkjet method. It may be attached by, for example.

  The ultraviolet curable resin 27 for the hard material layer adheres to the soft material layer 21 in a certain amount, and then, as shown in the process S6 of FIG. 1 and FIG. The ultraviolet curable resin 27 is cured. In addition, as length L2 of the hardened hard material layer 31, about 100 micrometers or less are suitable in general, and 15-40 micrometers is more suitable. The UV curing time is preferably about 10 seconds to 3 minutes.

  As described above, the ferrule 11 with a refractive index adjusting film in which the refractive index adjusting film 33 including the soft material layer 21 and the hard material layer 31 is formed on the one end portion 11a is obtained, and the manufacturing is finished.

FIG. 4 is an enlarged cross-sectional view of the main part in the vicinity of the refractive index adjustment film showing an example of connecting a single-core optical fiber to a ferrule manufactured by the ferrule manufacturing method according to the present invention.
After the ferrule is attached to the connector as shown in FIG. 5 and the optical fiber is inserted, a test process is performed. In the test process, the connector to be tested is connected to another connector (such as an SC connector). Next, communication light is input from the optical fiber 35 side, and optical characteristics (connection loss / reflection loss) are confirmed. If the connection loss is smaller than 0.7 dB, it is judged as “good”, and if it is larger than this, it is judged as “bad”. If the reflection loss value is larger than 40 dB, it is judged as “good”, and if it is less than this value, it is judged as “bad”.

  In the refractive index adjustment film 33, it is essential that the soft material layer 21 is provided inside. This is because the refractive index adjustment film 33 needs to immediately stick to the optical fiber 35 when the optical fiber 35 is inserted. Then, due to the possibility of breaking the soft material layer 21 when the optical fiber 35 is inserted or repeated connection work with another optical connector, a shearing force is applied to the entire soft material layer 21 and the like, and the soft material layer 21. May peel off from the ferrule or the glass fiber, it is necessary to provide the hard material layer 31 on the soft material layer 21 (outside).

  The soft material layer 21 needs to be formed inside the ferrule 11 as a film having a constant thickness L1. At this time (when the soft material layer 21 is provided as a film in the optical fiber holding hole 13), the ultraviolet curable resin liquid 15 for the soft material layer is sucked into the optical fiber holding hole 13 by a predetermined length A by using a capillary phenomenon or the like. There is a need. These sucked amounts (film thickness L1 of the soft material layer 21) are important control factors such as the resin temperature during the ferrule immersion (exactly “viscosity” that changes depending on the temperature during the immersion), the immersion time, and the like.

  The refractive index adjustment film 33 needs to ensure a certain thickness (L1 + L2). This is for maintaining the mechanical characteristics when the connector is attached and detached and when the fiber is inserted. That is, for the purpose of preventing the refractive index adjustment film 33 from being broken during attachment / detachment, the hard material layer 31 needs to have a constant film thickness L2. The reason why the refractive index adjusting film 33 cannot have a certain length or more is that when the refractive index adjusting film 33 is thick, the film permeability of light transmitted through the sheet is reduced. .

Next, an optical connector using the ferrule 11 with a refractive index adjusting film will be described.
FIG. 5 is a cross-sectional view of an optical connector including a ferrule on which a refractive index adjusting film is formed.
The refractive index adjusting film 33 is provided at the tip of a ferrule 11 for inserting and fixing the optical fiber 35 or a plug (also referred to as an optical connector) including the ferrule 11.

  In the present specification, the ferrule 11 has an optical fiber holding hole 13 for aligning the optical fibers 35, and the optical fiber 35 is fixed in the optical fiber holding hole 13. It connects while protecting. The plug is used to fix the ferrule 11, improve handling at the time of connection, and fit with another connection member such as an adapter.

  The number, type, material, and the like of the optical fiber 35 to be optically connected in the optical connector (site-attached optical connector) 100 that is a plug are not limited at all, and can be appropriately selected according to the application. For example, the optical fiber 35 may be a single mode fiber, a multimode fiber, a hole assist fiber, or the like, and the material may be quartz, plastic, or the like. The optical fiber 35 is a glass fiber 3a covered with a jacket 3b. The glass fiber 3 a from which the outer sheath 3 b of the optical fiber 35 is removed is inserted into the optical fiber holding hole 13 of the ferrule 11.

  The optical connector 100 is attached to the end of the installed optical fiber 35. In the on-site optical connector 100, the optical fiber 35 is cut and inserted into the ferrule 11 without polishing the end face 35a (see FIG. 4). At this time, since the end face 35a is not polished, there are slight irregularities. The counterpart optical fiber is a connector attached at the factory, and the end face is polished. When these are connected, a minute gap is formed between them. Therefore, connection loss increases. In order to eliminate this, a refractive index adjusting film 33 is interposed between the two. For this purpose, the refractive index adjusting film 33 is provided on the front end surface 25 of the ferrule 11 in which the optical fiber holding hole 13 is opened.

  With the soft soft material layer 21 facing the field-attached optical connector 100 side, the minute unevenness of the end face 35a of the optical fiber 35 is absorbed, and the refractive index adjusting film 33 is adhered to the optical fiber end face 35a. The end face of the optical fiber of the counterpart optical connector hits the hard material layer 31, but since the end face of the optical fiber is polished, the hard material layer 31 is in close contact with the end face of the optical fiber.

  The optical fiber 35 inserts the glass fiber 3 a from the other end portion 11 b side where the refractive index adjusting film 33 is not provided, and abuts against the refractive index adjusting film 33. The refractive index adjusting film 33 may be slightly pushed up (projected) by being pushed by the glass fiber 3a.

  The optical fiber 35 may be inserted into the ferrule 11 by removing the outer cover 3b and exposing the glass fiber 3a as usual. The optical connector 100 includes a main body portion 37 through which the optical fiber 35 is inserted and fixed, and a ferrule 11 made of, for example, zirconia that is fitted into the main body portion 37 and communicates with the main body portion 37 and the optical fiber holding hole 13. The main body 37 and a housing 39 that covers a part of the ferrule 11 protruding from the main body 37.

  The main body 37 includes a base member 41 with the ferrule 11 fitted and mounted at the tip thereof, an extra length accommodating portion lid member 43 stacked on a notch 41a at the rear of the base member 41, and a fixing means as a fixing means. The lid member 45 includes a lid member 43 and a clamp member 47 that clamps and fixes the lid members 43 and 45 stacked on the base member 41 integrally with the base member 41. The base member 41 has a fiber insertion portion 49 through which the optical fiber 35 is inserted, and a ferrule fitting hole 51 into which a proximal end portion of the ferrule 11 is fitted is formed on the distal end side.

  Above the fiber insertion portion 49, an extra length accommodation space 53 for accommodating the extra length (flexible portion) 3d of the optical fiber 35 is defined. The clamp member 47 is formed by, for example, press molding of a metal plate for a spring, and the lid members 43 and 45 are clamped by sandwiching the upper surface of the lid members 43 and 45 and the lower surface of the base member 41. Fix to the base member 41.

  The optical connector 100 of this embodiment bends the optical fiber 35 and accommodates it in the extra-length accommodating space 53. The glass fiber 3 a from which the outer sheath 3 b at the tip of the optical fiber has been removed is inserted into the optical fiber holding hole 13 from the coating removal portion 55. The length of the optical fiber 35 to be inserted into the optical connector 100 is pushed longer than the length of the optical connector 100, and the optical fiber 35 is bent in the extra length accommodating space 53 to form the bent portion 3d. The optical fiber 35 is fixed by the fixing lid member 45 in the state. As a result, the optical fiber 35 is fixed in a bent shape in the extra length accommodating space 53. The optical connector 100 can be attached to the optical fiber 35 by a simple operation of inserting and fixing the optical fiber 35 without removing the outer cover of the optical fiber 35 and inserting it.

  A refractive index adjusting film 33 composed of two layers is formed on one end of the ferrule 11.

  In the above-described embodiment, the manufacturing method for forming the refractive index adjusting film 33 on the single ferrule 11 has been described. However, the ferrule manufacturing method according to the present invention manufactures a large number of ferrules 11 at the same time. Of course, in this case, the productivity can be increased and the manufacturing cost of the ferrule 11 can be further reduced.

11 Ferrule (Ferrule with refractive index adjustment film)
11a One end part 11b The other end part of the ferrule 13 Optical fiber holding hole (a part inside the ferrule)
15 UV curable resin for soft material layer 17 Cap 19 UV light 21 Soft material layer 27 UV curable resin for hard material layer 31 Hard material layer 33 Refractive index adjusting film comprising two layers 100 Optical connector

Claims (5)

UV curable resin is attached to one end of the ferrule,
The ultraviolet curable resin is irradiated with ultraviolet rays and cured to form a soft material layer,
Adhering another UV curable resin with a large Young's modulus after curing on the soft material layer,
A ferrule manufacturing method comprising: forming a hard material layer by irradiating an ultraviolet ray to the other ultraviolet curable resin to form a hard material layer, and forming a refractive index adjusting film having two layers at one end of the ferrule. The ferrule manufacturing method according to claim 1,
When forming the soft material layer, the ferrule tip is immersed in an ultraviolet curable resin liquid for the soft material layer to attach the ultraviolet curable resin for the soft material layer to a part and one end of the ferrule,
The other end of the ferrule is sealed with a cap, and the ferrule is taken out from the ultraviolet curable resin liquid for the soft material layer,
Irradiate ultraviolet rays to cure the ultraviolet curable resin for the soft material layer,
An ultraviolet curable resin for a hard material layer is attached on the soft material layer,
A ferrule manufacturing method characterized by irradiating ultraviolet rays to cure the ultraviolet curable resin for the hard material layer. The ferrule manufacturing method according to claim 1 or 2,
A ferrule manufacturing method, wherein the soft material layer is cured by irradiating ultraviolet rays from below the ferrule that is erected with the one end portion as a lower end. The ferrule manufacturing method according to claim 2,
A method for producing a ferrule, comprising: using a transparent member for the cap to irradiate ultraviolet light from above the ferrule that is erected with the one end portion as an upper end, and curing the soft material layer. A ferrule manufactured by the ferrule manufacturing method according to any one of claims 1 to 4,
The ferrule with a refractive index adjusting film, wherein the soft material layer enters a part of the inside of the ferrule.

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