JP3289751B2 - Removal method of adhesive for optical connector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector used for connecting a silica-based optical fiber used for optical communication and the like, which is attached to an end face of a ferrule when assembling a ferrule of the optical connector . The present invention relates to a method for removing an adhesive , and more particularly to a method for treating an end face of a ferrule using an elastic adhesive-removing sheet for an optical connector having a polishing layer on a sheet on which open-cell cells are formed.

[0002]

2. Description of the Related Art One of the optical fiber connection methods is a method in which plugs are inserted into adapters from both sides thereof to connect them. Examples of this include: Sugita, R .; Nag
ase, K .; Kanayama and T.K. Shin
Taka, "SC-TypeSingle-Mode"
Optical Fiber Connector
s, "(J. Lightwaw Technol.,
vol. 7, No. 11, pp. 1689-1696
1989. 4), the structure shown in FIG. 4 is common. The plug 81 incorporates a ferrule 42 holding the optical fiber 41 at the center, and the ferrule 42 acts on the axis of the alignment sleeve 911 of the adapter 91. A coupling portion 811 for coupling with the adapter 91 is provided around the ferrule 42 of the plug 81.
A coupling portion 912 that fits with the coupling portion 811 is provided around the alignment sleeve 911.

[0003] As exemplified in FIG.
Is a substantially cylindrical member, and a ferrule main body 421,
And a flange 422 fixed to the rear end. The ferrule main body 421 is formed with a through hole 423 penetrating the center thereof in the longitudinal direction (along the axis), and the tip 424 is formed flat. Although some ferrules have a convex spherical surface at the tip, they are generally formed in a flat surface. Therefore, in the following description, a ferrule formed in a flat surface will be described.

The through-hole 423 formed in the ferrule main body 421 is used for tightly accommodating each of the optical fiber 41 and the optical fiber core 40 covered with an outer cover 411 for protecting the optical fiber as shown in FIG. The optical fiber 41 is fixed to the ferrule 42 with an adhesive (for example, an epoxy-based adhesive). After the optical fiber 41 is fixed, the tip is formed into a final shape, for example, a convex spherical shape, a planar shape, or an oblique convex spherical shape. It is precisely polished to a shape and the like. However, general polishing of a convex spherical surface will be mainly described below. Note that the ferrule main body 421 is usually made of a material such as ceramics (for example, zirconia ceramics, alumina ceramics) or metal (for example, stainless steel, tungsten carbide, or the like).

[0005] Fig. 6 shows an example of a work process of bonding and fixing an optical fiber and a ferrule and polishing. FIG.
As shown in (a), first, the optical fiber 41 from which the outer sheath 411 at the tip of the optical fiber core 40 and the primary coat (not shown) inside the outer sheath are removed is filled with an adhesive 50. The ferrule 42 is inserted to a predetermined position. Next, the adhesive is cured (FIG. 6B).
Next, as shown in FIG.
The excess optical fiber portion 412 that has been cut off
Fold it out using 0 or the like. Further, the fiber portion 413 and the adhesive 50 protruding from the ferrule tip 424 shown in FIG. 6C are removed as shown in FIG. 6D.

Finally, the tip 424 of the ferrule is
As shown in (e), it is precisely polished into a convex spherical shape.

In order to obtain good characteristics and long-term reliability when connecting an optical fiber to an optical connector, it is required that the final end face of the ferrule polished with a convex spherical surface has a precise convex spherical shape. Is done. For example, T. Shin
Taku, R .; Nagaseand E. Sugita
“Connection mechanism of
physical-contact optical
fiber connectors with sph
erical convex Polished en
ds, "(Applied Optics, vol. 3).
0, No. 36, pp. 5260-5265,199
According to 1), the radius of curvature r of the convex spherical surface of the ferrule tip 424 is a predetermined value (for example, 20 mm) in the final shape of the ferrule that has been precisely convex spherically polished as shown in FIG.
And the deviation e between the polished vertex and the fiber center e
(Hereinafter, referred to as a polishing vertex eccentric amount) needs to be equal to or less than a predetermined amount (for example, several tens μm). Further, the relative position w (hereinafter referred to as a fiber pull-in amount) between the polished convex surface and the end face of the optical fiber needs to be very small (for example, 0.1 μm or less).

In order to realize such a precise ferrule end face shape, the step of removing the adhesive at the time of assembling the ferrule (FIG. 6D) is important. That is, the end surface 424 of the ferrule 42 must be finally formed with a precisely convex spherical surface as described above. However, if the ferrule end surface after the removal of the adhesive is defective, the final shape after the precision convex spherical surface polishing is not obtained. There are cases where the shape does not become the predetermined shape.

[0009] As shown in FIG.
Is fixed to the ferrule 42 with an adhesive. At this time, the fiber comes out from the tip of the ferrule and the adhesive overflows from the tip of the ferrule. Therefore, FIG.
As shown in (d), it is necessary to remove the extra optical fiber 412 and the extra adhesive 50. In this adhesive removing step (FIG. 6D), usually, fine sandpaper (for example, emery paper or the like in which diamond particles or silicon carbide particles are fixed as an abrasive) or the like is used, and the tip of the ferrule tip is manually polished. Extra fiber and adhesive have been removed. In this case, the abrasive having high hardness not only cuts off the excess fiber and adhesive but also often cuts off the ferrule tip made of zirconia or the like.
The shape of the tip of the ferrule is broken as shown in FIG. In the figure, reference numeral 60 denotes a cut-off portion. Since the precise convex spherical polishing performed in the next step (FIG. 6E) is usually performed using the tip of the ferrule after removing the adhesive as a reference surface, for example, as shown in FIG. If the shape of the end surface of the ferrule is a defective polishing surface 425, the polishing of the convex spherical surface is not successful. For example, the polishing defect such as the eccentricity e of the polishing apex in FIG. 7 being large or the convex spherical curvature radius r not being a predetermined value is caused. Cause. In this case, a relatively deep scratch (for example, 1
μm to more than 10 μm) occurred on the end face of the ferrule, and even if the next step of precision convex spherical polishing was carried out, this flaw was left, and a smooth polished surface could not be obtained. Further, FIG.
As shown in (b), when the polishing material breaks the fiber or selectively cuts the fiber portion, and a defect 426 in which the fiber fracture surface enters a position deeper than the end surface of the ferrule occurs, a convex spherical polishing step is performed. However, a relatively large (for example, 0.1 μm or more) fiber pull-in remains,
A predetermined shape (for example, a fiber drawing amount w <0.1 μm)
m) could not be obtained.

For this reason, conventionally, the adhesive is removed by using fine sandpaper as described above (for example, emery paper on which diamond particles or silicon carbide (for example, carborundum; trade name) particles are fixed as abrasives). If you do
As shown in FIG. 9A, the adhesive is not completely removed at the time of removing the adhesive, but is thinly (for example, the thickness of the remaining adhesive is 0.1%).
(approximately mm). In the figure, reference numeral 51 denotes an adhesive layer left thin. By leaving the adhesive in this way, it is possible to avoid polishing to the end face of the ferrule, and FIG.
As shown in (a) and (b), the occurrence of defects in the shape of the ferrule end face, such as the defective polishing surface 425 or the defect 426 in which the fiber end face has penetrated deep, was avoided. However, this method has a disadvantage that the adhesive must be removed while checking the state of removal of the adhesive one by one, which is troublesome. In addition, the remaining adhesive layer needs to be 0.1 mm or less. However, such processing requires skill, and there is a problem that the cost is increased as a result. In addition, when the remaining adhesive layer is thick, the polishing accuracy may be degraded at the time of precision polishing in the next step, or the polishing time may be longer than usual. Furthermore, when a large number of ferrules are attached to a jig and the adhesive is removed in a lump using this method, the adhesive remains thick due to variations in the fixing position of the ferrule, and conversely, the end of the ferrule is scraped. And the removal state of the adhesive varies, and there is a disadvantage that it is difficult to collectively process many pieces.

In addition to the above-described method, as shown in FIG. 9B, after the adhesive is removed, a separate grinding step is added before precision polishing, and the shape after the adhesive is removed by a dedicated grinding device. Was formed to form the re-polished surface 427. That is, this is a method of re-grinding the defective end face after removing the adhesive so that the shape of the ferrule is symmetrical with the center of the ferrule. By re-grinding and shaping the end face shape, the defective end face shape at the time of removing the adhesive is prevented from reaching the next step of the precise convex spherical polishing step. Alternatively, as shown in FIG. 9C, the polishing time for forming the fine convex spherical surface polishing 428 is increased to increase the polishing margin, and the defective shape at the tip of the ferrule after removing the adhesive is largely polished. Thus, the above-described shape defect after removing the adhesive does not affect the final polished shape. In some cases, the removal of the adhesive has been carried out precisely using a polishing material, a polishing liquid and a polishing apparatus dedicated to removing the adhesive. In any case, it is necessary to replenish the abrasive, control the apparatus, and the like, and there is a disadvantage that the manufacturing cost increases.

Further, the conventional ferrule has a diameter of 2.5 mm.
However, with the recent miniaturization of optical connectors, thin ferrules having a diameter of about 1 mm have been used. As the ferrule diameter decreases, more precise processing is required. That is, as shown in FIG. 9C, a tapered guide portion 429 of about 0.4 to 0.5 mm on one side is provided at the tip 424 of the ferrule 42 for guiding at the time of coupling the optical connector. I have. Therefore, the allowable diameter D of the polished surface is obtained by subtracting twice the size Wg of the tapered guide portion from the ferrule diameter Df. In the case of a 2.5 mm diameter ferrule, the polished surface excluding the guide portion has a diameter of about 1.5 mm, whereas in the case of a thin ferrule, for example, a 1.25 mm diameter ferrule, the polished surface has a diameter of 0 mm. It is about 0.5 mm. Thus, in the case of a small-diameter ferrule, the area of the polished surface is 2.5
It is about one-tenth that of a ferrule having a diameter of mm. Therefore, in a ferrule having a smaller diameter than a ferrule having a diameter of 2.5 mm, the tip of the ferrule is more easily shaved during the removal of the adhesive, and the above-described defective shape at the time of removing the adhesive, and further, after polishing the convex spherical surface in the final state. There has been a problem that shape defects are likely to occur.

[0013] In addition to the above-mentioned emery paper and the like, various polishing sheets having an abrasive coated on an elastic body have been developed as polishing sheets. These do not polish part of the object (the ferrule itself) and other extra parts (adhesive,
Rather than selectively finishing only the excess optical fiber portion into a predetermined shape, the main purpose is to smooth the entire surface of the object. For this reason, any kind of material is used with an abrasive that can be polished uniformly and efficiently, and its structure is optimized. For example, a polishing tape in which a polishing layer containing an abrasive is formed on a polyester sheet (or a roll) is sometimes used. This tape has flexibility and facilitates the polishing operation according to the surface of the object to be polished.

A polishing tape having a polishing layer formed on a foamed base sheet is also used (US Pat. No. 4,963).
6,609). The cells in this sheet are closed cell cells, and no air bubbles are exposed on the surface.

Further, a sheet (buff) in which a polishing layer is not formed on a sheet is also used for polishing. Polishing with such a sheet is performed by applying an appropriate amount of an abrasive on a body to be polished, and sliding the sheet by pressing the sheet.

[0016]

As described above, in the prior art, not only the excess adhesive and the optical fiber but also the tip of the ferrule is scraped off in the adhesive removing step, and the end face of the ferrule is removed in the next precision polishing. However, there is a disadvantage that the shape cannot be formed with high accuracy. In addition, as a method of removing the adhesive with high accuracy, there is a method of adding a grinding process, lengthening a polishing time, or using a device for precise adhesive removal, but in these cases, However, there is a disadvantage that the cost of assembling the optical connector increases. Also, it has been difficult to efficiently and easily remove the adhesive from the multi-core fiber.

A polishing sheet having a polishing layer formed on the above-mentioned polyester sheet has flexibility but poor elasticity. For this reason, the polishing force cannot be adjusted depending on the pressure of pressing the ferrule against the polishing sheet, so that not only the optical fiber but also the end face of the ferrule formed accurately may be cut off. Further, fine polishing particles and shavings peeled off from the polishing layer exist between the polishing layer of the sheet and the end faces of the optical fiber and the ferrule, and may be damaged.

The polishing sheet using the closed-cell sheet has elasticity, and the polishing force can be adjusted by pressing pressure of the ferrule against the polishing sheet. However, similarly to the above-mentioned polishing sheet, fine polishing particles and shavings peeled off from the polishing layer exist between the polishing layer of the sheet and the end faces of the optical fiber and the ferrule, and may be damaged.

In the case of a conventional polishing sheet 440, that is, a polishing sheet in which bubble cells are not exposed, or a polishing sheet in which an abrasive is applied to the surface of a normal elastic body, especially at the final stage of removing the adhesive, FIG. As shown, the sheet is pushed at the periphery (edge portion 430) of the tip 424 of the ferrule 42, and this pressure causes the sheet to elastically dent, so that sufficient pressure is not applied to the portion in contact with the center of the ferrule. . If the ferrule is further pressed and polished in this state, the edge portion 43 around the ferrule is particularly damaged.
An excessive force is applied to 0, and this force causes the peripheral portion of the tip of the ferrule to be more sharply cut than the central portion of the ferrule, causing a shape defect as shown in FIG.

Further, when an appropriate amount of abrasive is applied to a sheet such as a buff, and the like is rubbed, fine particles of the abrasive enter into the holes of the sheet during the polishing operation to produce an abrasive which does not contribute to the polishing. The amount of the abrasive was constantly monitored, and if it was insufficient, the abrasive had to be replenished.

[0021] The object of the present invention is given in view of the circumstances described above,
It is an object of the present invention to provide a method for removing an excess adhesive and an optical fiber without breaking a shape of a ferrule tip. In this case, it is necessary to realize a shape in which the end face of the optical fiber does not enter at least deeper than the end face of the ferrule. In addition, these adhesives for optical connectors can be realized in a short time, at low cost, and easily without using expensive equipment, abrasives, or polishing liquids.
To provide a method for eliminating the Further, there is provided a method for removing the adhesive for an optical connector , which removes the adhesive of all the ferrules and allows the end face shape of the removed ferrule to have the desired shape when a plurality of cores are collectively processed. That is. Specifically, using an abrasive, a polishing liquid, etc.
Without using an inexpensive adhesive removal sheet, dry and simple hand polishing sufficiently removes the adhesive and excess optical fiber, and at this time, the ferrule itself is not polished and the optical fiber has a predetermined shape, that is, An object of the present invention is to provide a method of removing a ferrule without drawing it in from an end face.

It is a further object of the present invention to provide an elastic adhesive.
Using an agent removal sheet, adjusting the pressing pressure of the polishing tape by adjusting the pressing pressure of the ferrule against the adhesive removal sheet, without removing the ferrule part and efficiently removing only the optical fiber and the adhesive It is to provide.

Another object of the present invention is to carry out the above-mentioned desired adhesive removal without refilling the adhesive removal sheet with abrasive.
Is to provide a method . Further, the object of the present invention is
An object of the present invention is to provide a method for removing an adhesive for an optical connector, which does not damage an end face of an optical fiber or an end face of a ferrule by fine particles or shavings of an abrasive removed from an adhesive removal sheet .

[0024]

According to the present invention, there is provided a method for removing an adhesive for an optical connector, comprising the steps of:
Fill the adhesive inside the ferrule incorporated in the lug,
Insert the fiber and project from the tip of the ferrule
Cure the adhesive and cut off excess optical fiber
This is the method of treating the tip of the ferrule after cutting and removing.
The extra optical fiber protrudes and the adhesive adheres
Further, at the tip of the ferrule, a foamed base sheet in which a part of open-cell cells is exposed on the surface, and formed on the cell-cell exposed surface of the foamed base sheet, the same as quartz glass.
Abrasive particles with high hardness or higher and aqueous
An adhesive removal sheet composed of a polishing layer composed of a polyurethane resin adhesive and a polishing layer is pressed, slid and polished .

In the present invention , the foam base sheet
However, an open-cell cell with a cell cell exposed on the surface is formed.
It is a polyurethane foam formed .

In the present invention , the abrasive is 0.3 to 4
It has a particle size of 0 μm .

In the present invention , the abrasive is silicon oxide;
It is characterized by being fine particles of alumina, silicon carbide or diamond .

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

The method for removing the adhesive for an optical connector according to the present invention is based on
Polishing adhesive-removed sheet that has elasticity due to having bubbles
When the ferrule is pressed against the surface, the portion protruding from the surface bites into the sheet, and a higher pressing pressure acts, so that the protruding portion can be more effectively scraped off.

Further, since residues such as the separated abrasive particles and shavings enter into the bubble cells, they are less likely to damage the fiber at the tip of the ferrule and the ferrule itself.

Further, in the method for removing an adhesive according to the present invention,
This eliminates the need for operations such as replenishment of the polishing liquid and the abrasive, thereby improving workability and reducing costs.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific structure of the present invention will be described below.

[0037] One implementation adhesive removing sheet used in example (or dust et <br/> eagle wards "removing sheet of the present invention" hereinafter simply referred to as "removing sheet") of the present invention in FIG. 1 An embodiment is shown. As shown in FIG.
It is based on the foamed base sheet 21 in which the open-cell cells are formed. The foamed base sheet 21 has a cell 22
And a part of the bubble cell 22 is exposed from one surface 21a. Also, the surface 2 of the foamed base sheet 21
1a, a polishing layer 23 is formed.

The foamed base sheet that can be used in the present invention is typically a foamed polyurethane foam having open cells. The open cells referred to here are those in which adjacent cells communicate. Further, in addition to the polyurethane foam, a PVC (polyvinyl chloride) foam, a polyolefin foam, or the like may be used.

Here, the foamed polyurethane foam can be formed by a conventional method, for example, as shown in FIG.
In FIG. 2, A is a reverse roll coater, B is a leveling zone, C is an overflow, D is a gelling water tank, E is a desolvating water tank, F is a peeling section, G is a PET film dryer, H is a desolvating water tank, and I is a dewatering tank. Denotes a immersion water tank, J denotes a film feeder, K denotes a first dryer, L denotes a second dryer, M denotes a third dryer, and N denotes a winder. In this method, for example, a PET (polyethylene terephthalate) film f is conveyed in a ring shape so as to pass through a PET film dryer G, a leveling zone B, a gelling water tank D, and a desolvating water tank E, and has a polyurethane resin on the surface. Is passed through a gelling water tank D and further through a desolvation water tank E (while the solvent dissolves and foams). Thus, PET film 1
Polyurethane foam sheet 200 formed on
Is peeled from the PET 100 at the peeling section F, washed in the desolvation water tank H and the immersion water tank I, and further dried in the drying chambers K, L, and M to become a base sheet. FIG. 1C shows the sheet 200 formed in this manner. The film 201 is formed on both sides 200a and 200b of the sheet 200, and the air bubbles 22 are not exposed outside the surface.

The hardness of the sheet 200, that is, elasticity, is as follows.
It is determined by the size and amount of bubbles and the thickness of the sheet. Therefore, depending on the use of the polishing sheet, these factors are adjusted to determine the hardness. Generally, hardness of 10 ° to 90 °
Is good, the thickness is about 0.1mm, the density is 1 ~
About 60 g / cm ² is preferable.

As described above, since the polyurethane foam sheet has a film formed on both sides thereof, at least one surface thereof (indicated by a broken line in FIG. 1C) is buffed with sandpaper or the like, and bubbles 22 near the surface are formed. By exposing the foamed base sheet 21 used in the present invention.
(FIG. 1B). If a polishing layer is formed on both surfaces, the air bubbles 22 are exposed on both surfaces.

The polishing layer 2 is formed on the sheet 21 having one surface buffed.
By forming No. 3, the adhesive removal sheet 20 is formed (FIG. 1A).

FIG. 3 shows an example of the formation of the polishing layer 23. The sheet 21 spread on a drum or the like is provided with guide rollers 2 and 3
Thereby, it is guided to the application rollers 4, 5, and 6. Here, the mixture of the abrasive and the adhesive stored in the pad 7 is applied to the sheet 2.
1 is applied. Next, the organic solvent is removed from the sheet by the dryer 8, and the tension rollers 9, 10, 11 are removed.
And the guide roller 12, and is wound around the bobbins 13 and 14 as the removal sheet 20.

As the abrasive, fine particles such as aluminum oxide, silicon carbide, zirconium oxide, chromium oxide, and diamond can be used. An optical fiber made of quartz and an adhesive used for fixing the optical fiber and the ferrule are made of zirconia. Silicon oxide is suitable for removing the tip of a ferrule made of ceramics such as aluminum or alumina or a metal such as stainless steel without shaving it. Even if the ferrule, the adhesive and the optical fiber are shaved together, if the fine particles of silicon oxide are used as an abrasive, the optical fiber and the adhesive are shaved and removed, but the ferrule is hardly shaved.

The abrasive having a particle size of 0.3 μm to 40 μm, preferably 1 to 30 μm is used. Depending on the purpose of use of the abrasive sheet, fine particles of abrasive having an appropriate particle size are selected.
If it is larger than 0 μm, precise finishing cannot be performed. This abrasive may be mixed with the adhesive solution that becomes the material of the sheet without heating, but is preferably mixed with the adhesive solution that becomes the material of the sheet after heating.

The adhesive used as the material of the removal sheet is preferably an aqueous polyurethane resin-based adhesive, and the diluting solution in which the adhesive is dissolved is preferably pure water. It is preferable to add 3% to 10% of a solvent such as an alcohol or a ketone to pure water because azeotropic distillation can be performed. The viscosity of the mixture of the abrasive and the adhesive used here is 80 to 15
0 cp and the coating speed is 8 to 16 m / min.

The sheet 20 dried by the dryer 8 is
Carrying is performed at a temperature of 0 to 130 ° C. for a time of 1 minute to 1 hour. The polishing sheet thus formed is shown in FIG. As can be seen from this figure, the polishing layer 23 containing the polishing material is formed along the bubble cells exposed from the surface of the sheet.

The adhesive-removed sheet thus formed has elasticity since open cells are formed therein. Therefore, as shown in FIG.
When the ferrule 42 is pressed against the removal sheet in order to scrape the optical fiber 413 and the adhesive 50 protruding from the end face 424, the protruding optical fiber 413 and the adhesive 50 bite into the removal sheet as shown in FIG. A large pressing force acts on these, and they can be scraped off. On the other hand, especially when the abrasive is silicon oxide, the ferrule 42 is not scraped.

FIG. 10 schematically shows a state in which the tip of the ferrule is pressed against the removal sheet of the present invention to remove the adhesive. Actually, the surface shape and internal structure of the removal sheet are finer than those in the drawing. As shown in the drawing, in the removal sheet of the present invention, the exposed cell cells 23 on the sheet surface individually contact the ferrule tip 424 to remove the adhesive. Therefore, in comparison with the polishing sheet shown in FIG. 11, for example, in which the cell is not exposed, in the removal sheet of the present invention, the polishing layer 24 of each cell works independently, and the optical fiber portion 412 at the center of the ferrule and the polishing layer 24 of the cell. The peripheral adhesive 50 can be efficiently and stably removed.

Here, when the ferrule is pressed against the removal sheet 20 and slid, the polishing layer 24 formed around the bubble cell 23 is exposed on the surface. The degree of the exposure depends on the pressing pressure of the ferrule against the removal sheet. In addition, residues such as fine abrasive particles and shavings separated from the polishing layer by the polishing operation using the removal sheet enter into the exposed bubble cells.

Using the removal sheet of the present invention, the diameter 1.
FIGS. 12A and 12B show the results of polishing a ferrule made of zirconia ceramics having a small diameter of 25 mm. As shown in FIG. 6C, the optical fiber 41 protrudes from the ferrule tip 424 and has excess adhesive.
The adhesive was removed by pressing against the removal sheet of the present invention, sliding the figure eight times ten times and polishing. FIG.
2 (a) shows the ferrule tip 424 measured by a surface roughness meter, and FIG. 2 (b) shows an enlarged measurement of the tip. As can be seen from FIG. 12, the excess adhesive and the optical fiber are completely removed, and the end face of the ferrule is hardly scraped, the initial planar shape is maintained, and there is no edge portion. Further, the tip of the optical fiber projects smoothly from the end face of the ferrule, and there is no pull-in from the tip of the ferrule. The amount of projection of the optical fiber from the end face of the ferrule is approximately 13 μm. Thus, the removal sheet according to the present invention can ideally and satisfactorily remove the adhesive.

FIGS. 13A and 13B show examples of polishing using a conventional polishing sheet (emery paper). Polishing conditions (pressing load, polishing operation, number of polishing, etc. are the same)
Was the same as above. Compared to the case where the removal sheet of the present invention is used (FIGS. 12A and 12B), the edge portion of the ferrule has a particularly sharpened shape, and the shape of the ferrule end surface 424 has a convex spherical shape. Has become. Furthermore, the ferrule end face 424 and the end face of the fiber 41
A relatively deep scratch of about μm has occurred. Also, the tip of the optical fiber 41 is polished deeper than the ferrule end face 424,
It is deeper than the ferrule end face. As described above, in the conventional polishing sheet, as described with reference to FIGS. 8A and 8B, the ferrule end surface 424 itself is also cut and the end surface shape is cut off, and the fiber 41 is cut larger than the ferrule and thus the ferrule is cut. This is a position retracted from the end surface 424.

FIGS. 14A and 14B show examples of polishing when the abrasive of the removal sheet of the present invention is alumina particles. The polishing conditions (the pressing load, the polishing operation, the number of polishing, and the like were the same) were the same as those described above.

As compared with the above embodiment (when the abrasive is silicon oxide fine particles; measurement examples are shown in FIGS. 12 (a) and 12 (b)), the peripheral portion of the ferrule is slightly shaved and the edge portion is slightly reduced. Although it has a sagging shape, the conventional example (FIG. 13)
Compared with (a) and (b)), the ferrule end face is hardly cut, the ferrule end face keeps a substantially planar shape, and the optical fiber is not drawn from the ferrule end face.
As described above, even when the abrasive is made of a material harder than quartz glass, the removal sheet of the present invention works independently of each other to remove excess adhesive and optical fibers, so that the conventional polishing sheet is used. And a better end face shape can be obtained. However, as compared with the case where the abrasive is made of silicon oxide fine particles, edge dripping occurs.

In the above-described embodiment, the present invention is applied to the removal of the adhesive of a 1.25 mm-diameter ferrule made of zirconia having a flat shape at the initial end face and a convex spherical shape at the final polishing, which is considered to be more severe conditions. However, when the present invention is applied to a ferrule having a larger diameter, a ferrule having a planar shape of a final polished shape, or a ferrule having an initial shape of a convex spherical surface, a better effect is obtained. Needless to say, it can be obtained.

Further, in the above embodiment, the abrasive is made of fine particles of silicon oxide. However, the same effect can be obtained by using fine particles of another abrasive having the same hardness or the same polishing rate.

In the above-described embodiment, one kind of abrasive is silicon oxide. However, the same applies to a case where a conventional high-hardness abrasive (silicon carbide or diamond fine particles) is slightly added to silicon oxide. Effect. In this case, although the polishing shape is slightly deteriorated, the polishing shape is almost the same as that when only one kind of silicon oxide is used, and the polishing time can be shortened.

[0058]

The method for removing the adhesive for an optical connector according to the present invention.
Has elasticity because the adhesive removal sheet used therein has air bubbles. Thus, when the ferrule is pressed against the polished surface of the sheet, the portion protruding from the surface bites into the sheet, and a higher pressing pressure acts, so that the protruding portion can be more effectively shaved off. Then, not only the polishing layer formed on the sheet surface at this time, but also the polishing layer formed along the bubbles contributes to the polishing. Therefore, even if the fine particles of the abrasive are peeled off by the polishing operation, pressing the ferrule against the sheet exposes the polishing layer formed along with the air bubbles, thereby enabling further polishing without replenishing the abrasive. Therefore, the sheet can be reused, and the adhesive of a large number of ferrules can be removed at low cost.

Even if the ferrule is pressed too much against the removal sheet or polished too long, the removal sheet does not grind the ferrule itself. For example, a large number of ferrules are attached to a jig and adhesive is applied at once. In this case, the excess adhesive and optical fibers of all the ferrules can be removed without variation.
Therefore, the efficiency of the adhesive removing step can be improved.

Further, since residues such as peeled abrasive particles and shavings enter the bubble cells, they also have the effect of reducing damage to the fiber at the tip of the ferrule and the ferrule itself. This eliminates the problem that the shape of the tip surface of the ferrule after the removal of the adhesive is different or deteriorated due to the difference in technology at the time of the removing operation. That is, a precise polished end face after removing the adhesive can be realized without requiring advanced technology or complicated work.

Further, in the adhesive removing step, there is no need to perform operations such as replenishment of a polishing liquid or an abrasive, and there is an advantage that workability can be improved and cost can be reduced. Further, a precise polishing device or the like is not required, and the cost can be reduced.
Further, there is an advantage that these residues can be discarded together with the sheet after polishing is completed.

[Brief description of the drawings]

FIG. 1A is a schematic sectional view of an adhesive removal sheet used in an embodiment of the present invention, FIG. 1B is a schematic sectional view of a foamed base sheet, and FIG. It is a schematic sectional drawing of a foam base sheet.

FIG. 2 is a schematic diagram illustrating an example of a production apparatus for a foamed base sheet.

FIG. 3 is a schematic view showing an example of an apparatus for forming a polishing layer on a foamed base sheet.

FIG. 4 is a partially sectional perspective view for explaining the structure of the optical connector.

FIG. 5 is a sectional view showing a structure of a ferrule.

FIG. 6 is a schematic view showing a process of assembling a ferrule of the optical connector.

FIG. 7 is a view showing a cross-sectional shape of a ferrule tip for explaining a shape of a ferrule end face precisely polished to a convex spherical surface.

8A and 8B are cross-sectional views of a ferrule tip for explaining an undesired shape of the ferrule end face after removing the adhesive, FIG. 8A shows a shape in which the ferrule tip is cut off, and FIG. This shows a shape in which the tip of the optical fiber is cut away at a recessed position.

9A and 9B are cross-sectional views for explaining a conventional method, in which FIG. 9A shows a method in which an adhesive is slightly left so as not to scrape the tip of a ferrule, and FIG. 9B shows a rough end surface after the adhesive is removed. A method for adjusting the shape of the end face by grinding is shown, and (c) shows a method for polishing a rough ferrule end face after removing the adhesive by a large convex spherical surface.

FIG. 10 illustrates a method for removing an adhesive for an optical connector according to the present invention.
FIG. 4 is a schematic diagram illustrating an operation when removing the adhesive at the tip of the ferrule using an adhesive removing sheet.

FIG. 11 is a schematic diagram illustrating an operation when removing an adhesive at the tip of a ferrule using a conventional polishing sheet.

FIG. 12A shows a state after removing an adhesive by the method of the present invention.
FIG. 7B is a diagram showing an example in which the shape of the end face of the ferrule is measured by a surface roughness meter, and FIG.

FIG. 13A is a diagram showing an example in which the shape of the end face of a ferrule after an adhesive removing step is measured by a surface roughness meter when a conventional polishing sheet is used, and FIG. It is a figure which shows the expansion measurement result of.

FIG. 14A shows a state after removing an adhesive by the method of the present invention.
FIG. 7B is a diagram showing an example in which the shape of the end face of the ferrule is measured by a surface roughness meter, and FIG.

[Explanation of symbols]

 Reference Signs List 20 adhesive removing sheet 21 base sheet 22 bubble cell 23 polishing layer 40 optical fiber core wire 41 optical fiber 42 ferrule 50 adhesive 424 ferrule end face r radius of curvature of convex spherical polishing end face of ferrule e polishing vertex eccentricity w ferrule pulling amount Df Ferrule diameter D Ferrule polishing surface diameter Wg Ferrule guide amount P Center of convex spherical polishing surface Q Ferrule center

Continuing from the front page (72) Inventor Kazunori Kanayama 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Kuniharu Kato 1-16-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Stock Inside the company (72) Inventor Ichifusa Noda 3- 10-28 Nishikubo, Musashino-shi, Tokyo Inside the Oshima Prototype Research Laboratory Co., Ltd. (72) Inventor Nobuyoshi Watanabe 3-4-1 Musashino, Akishima-shi, Tokyo Nihon Micro Coating Co., Ltd. In-company (72) Inventor Toru Yamazaki 3-4-1 Musashino, Akishima-shi, Tokyo Nihon Micro Coating Co., Ltd. (56) References JP-A-63-174878 (JP, A) JP-A-5-164943 ( JP, A) JP-A-4-101764 (JP, A) JP-A-6-67033 (JP, A) JP-B-48-18199 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B24D 11/00 B24B 19/00 603 G02B 6/36

Claims (4)

(57) [Claims] 1. A ferrule incorporated in an optical connector plug.
Fill the inside of the rule with adhesive, insert the optical fiber, and
The adhesive is cured by projecting from the tip of the rule,
The ferrule after cutting and removing the excess optical fiber
This is a method of treating the tip of the tool, before the extra optical fiber protrudes and the adhesive adheres.
At the tip of the ferrule, a foamed base sheet in which a part of open-cell cells is exposed on the surface, and formed on the cell-cell exposed surface of the foamed base sheet, may be equivalent to quartz glass.
Are abrasive fine particles with higher hardness and aqueous poly
A method for removing an adhesive for an optical connector , comprising pressing an adhesive removal sheet composed of a polishing layer composed of a urethane resin adhesive and sliding it and polishing . 2. The method for removing an adhesive for an optical connector according to claim 1, wherein the foamed base sheet is a polyurethane foam formed with open cells having cell cells exposed on the surface. 3. The method for removing an adhesive for an optical connector according to claim 1, wherein the abrasive has a particle size of 0.3 to 40 μm. 4. The method for removing an adhesive for an optical connector according to claim 1, wherein said abrasive is fine particles of silicon oxide, alumina, silicon carbide or diamond.