JP3929405B2 - Optical fiber connection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical fiber connecting device for connecting plastic optical fibers used in the fields of information home appliances, communication networks, computers, peripheral devices, and the like.
[0002]
[Prior art]
There are various types of optical fibers, such as a quartz glass type and a multicomponent glass type, and one of them is a plastic type optical fiber. In this plastic optical fiber (hereinafter referred to as an optical fiber as appropriate), polymethyl methacrylate or a derivative thereof is generally used as a core material, and a fluorine-based resin is used as a cladding material. Such an optical fiber has a large diameter such as a fiber diameter of 1000 μm and a core diameter of 980 μm, and is capable of transmission regardless of dirt and scratches on the connection end face and optical axis shift, and is inexpensive. It has characteristics and is often used in communication systems with short transmission distances.
[0003]
When connecting such an optical fiber, although not shown, a ferrule that holds the optical fiber at the center is generally inserted into the sleeve, the optical axis is aligned, and the ferrule and the sleeve are fixed by a locking member of the connecting device. In addition, in order to reduce transmission loss, the connection end face of the optical fiber is processed into a flat surface. This processing heats the cut connection end face in view of the fact that the optical fiber material is plastic. This is done by pressing against a mirror surface and transferring the surface. Thus, the optical fiber is connected by contacting the processed connection end face after the connection end face is processed from the irregular surface to the flat surface.
[0004]
By the way, although wiring in homes and automobiles in recent years has a short transmission distance, it has become complicated and the number of connection points or branch points has increased, so in the connection of conventional optical fibers, transmission loss becomes large and reaches the end. A problem has arisen that the signal is not well received.
Therefore, various proposals have been made to solve such problems. For example, a proposal has been made that glass optical fibers are aligned with a V-shaped groove as a guide, the optical axes are aligned, the silica gel is solidified, and the glass fibers are joined together (see Patent Document 1). In addition, proposals have been made to interpose a gel-like pad such as silicone resin or epoxy resin when connecting optical fibers (see Patent Documents 2 and 3). A gel-like pad having a thickness of 0.5 to 2 mm is provided by being mechanically sandwiched between splittable sleeves.
[0005]
[Patent Document 1]
JP-A-5-264847 [Patent Document 2]
Japanese Patent Laid-Open No. 11-258476 [Patent Document 3]
Japanese Patent Laid-Open No. 10-111129 [0006]
[Problems to be solved by the invention]
However, the technique of Patent Document 1 uses a gel for joining glass optical fibers and has high matching performance such as optical characteristics, time-varying characteristics, temperature characteristics, etc. Unlike the optical fiber made of plastic having a large diameter, there is a problem that it is very troublesome to solidify a joining member such as silica gel. In addition, a cover must be applied to the groove, which is far from convenient.
[0007]
Further, in the techniques of Patent Documents 2 and 3, since the gel-like pad can be exchanged, it is sandwiched between the divided sleeves and mechanically fixed. There is a problem of causing an increase. Further, when there are many joints, there is a disadvantage that the transmission loss is increased in total. Furthermore, since the gel-like pad is thick and the transmission loss is increased, the gel-like pad is becoming thinner. The thin gel-like pad is sticky and has a diameter of several mm and a thickness of 0.00. Providing a pad with a thickness of 5 to 2 mm between the divided sleeves is not only difficult and difficult to handle, but also has a problem that productivity is poor and practical application is difficult.
[0008]
The present invention has been made in view of the above, and an object of the present invention is to provide an optical fiber connecting device that can utilize the simplicity of processing, which is a feature of an optical fiber made of plastic, and can be easily joined. It is said.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention includes a sleeve, a plurality of optical fibers made of plastic that are inserted into the sleeve and face each other, and a ferrule that is fitted into a facing portion of each optical fiber and inserted into the sleeve. Which consists of
Inside the sleeve, the transparent resin thin film positioned between the plurality of optical fibers opposing provided, along with the range of the shear modulus of the transparent resin film ^{5 × 10 4 ~1 × 10 7} Pa, the transparent resin It is characterized in that an antistatic treatment is applied to the thin film .
[0010]
Further, the transparent resin thin film can be formed in a substantially disc shape, and the thickness of the adhesion region at the outer peripheral portion can be made thicker than the thickness of the substantially central portion.
Moreover, the substantially center part of a transparent resin thin film can be 0.05-0.5 mm thick.
Further, the transparent resin thin film can be an organopolysiloxane.
[0011]
Here, the number of sleeves in the claims may be one or more. The excess portion relief gap may be formed in a ferrule, a transparent resin thin film, or may be formed in both of them. The optical fiber connecting device according to the present invention can be used for connecting optical fibers in digital information home appliances such as camcorders, videos, and televisions, and communication networks. Further, it can be used for a home network for transmitting large-capacity real-time data easily and at low cost between a printer, a PC peripheral device and a PC main body. In addition, for user interfaces with drivers and passengers in automobiles, information systems that handle multimedia such as video and audio, and other connections for optical fibers used in car networks such as body systems, chassis systems, and power control systems. It is also possible to use it.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the present invention will be described below with reference to the drawings. An optical fiber connecting device according to the present embodiment includes a plurality of sleeves 2 arranged side by side in a housing 1 as shown in FIGS. A pair of plastic optical fibers 3 inserted into opposite ends of each sleeve 2 and opposed to each other, and fitted to opposite ends of each optical fiber 3 and held in the center, and each sleeve 2 A transparent resin thin film that bonds and integrates a transparent resin thin film 5 interposed between a pair of opposing optical fibers 3 to each sleeve 2 and joins the pair of optical fibers 3 together. The shear modulus of 5 is in the range of 5 × 10 ⁴ to 1 × 10 ⁷ Pa.
[0013]
As shown in FIGS. 1 to 3, the housing 1 is formed in a box shape having a substantially H-shaped cross section, and a sleeve 2 is penetrated and supported in a horizontal row at the center of the inside. Further, as shown in FIGS. 1 to 3, the sleeve 2 is formed into a straight tube shape having an inner diameter of about 1 to 4 mm and a length of about 10 to 30 mm using a predetermined material, and a transparent resin thin film 5 is formed therein. Bonded and fixed. Examples of the material for the sleeve 2 include liquid crystal polymer, polyester engineering plastic, epoxy resin, etc. that have high fluidity, low thermal expansion, and low dust generation so that the joining accuracy is high and inexpensive. Molded with a micron level accuracy of 10 μm or less by a method or the like.
[0014]
Each optical fiber 3 is formed with a small joining area at the connecting end face, which is the tip, and functions to stabilize the joining. The connecting end face of the optical fiber 3 is flush with the tip face of the ferrule 4 or is slightly protruded from the tip face of the ferrule 4 and supported (see FIG. 4) to minimize the deviation of the optical axis. In addition, it is formed into a structure that can be bonded with low stress.
[0015]
The ferrule 4 is formed in a substantially cylindrical shape having an outer diameter of about 1 to 4 mm. The ferrule 4 is made of the same material as that of the sleeve 2 and is formed with an accuracy of micron level of 10 μm or less by an injection molding method or the like.
The shape of such an optical fiber connecting device is being standardized by PN standard (JIS C5976), F07 standard (JIS C5976), SMI standard, SMA standard and the like.
[0016]
The transparent resin thin film 5 is basically formed in a substantially disk shape having the same diameter as the inner diameter of the ferrule 4, and the connection end faces of the pair of optical fibers 3 facing each other are bonded and fixed to the inner center of the sleeve 2. Join. This transparent resin thin film 5 is not only bonded to the sleeve 2 for mere holding, but also when the optical fiber 3 is inserted and removed, it adheres with an adhesive force larger than the adhesive force with the optical fiber 3 or the ferrule 4. Otherwise, it will be peeled off and destroyed, so that it is necessary to have a large adhesion area in order to obtain sufficient adhesion.
[0017]
Therefore, as shown in FIG. 5, the transparent resin thin film 5 is formed in a substantially I shape, and the thickness of the adhesion region of the outer peripheral portion 6 that adheres to the sleeve 2 is the central portion where the tip of the optical fiber 3 or the ferrule 4 contacts. 7 is formed to be thicker than 7. The adhesive strength of the outer peripheral portion 6 of the transparent resin thin film 5 is approximately 50 to 300 g, although it varies depending on the adhesion force or the adhesive area between the optical fiber 3 or the ferrule 4 and the transparent resin thin film 5. This is because the strength of the transparent resin thin film 5 itself must be higher than this, and if it is low, the base material is destroyed.
[0018]
However, it is preferable that the contact portion of the optical fiber 3 has a sufficient thickness so that the central portion 7 of the transparent resin thin film 5 is in close contact with the connection end face of the optical fiber 3 with low stress. The thickness of the central portion 7 of the transparent resin thin film 5 is 0.03 to 0.4 mm in a state where the optical fibers 3 are joined together, that is, in a pressurized state, and 0.05 to 0 in a free thickness that is not pressurized. .5 mm. This is because if the thickness is larger than this range value, transmission loss increases, and there are restrictions on the junctions in the transmission circuit system, making it impossible to route a free circuit. On the contrary, if the thickness is smaller than the range value, a problem occurs in the durability of the transparent resin thin film 5.
[0019]
It is preferable that the transparent resin thin film 5 has a large free thickness because the allowable range of molding accuracy of the locking portion and the like is expanded. However, the amount of deformation by the optical fiber 3 is increased and the internal stress is increased, so Therefore, a surplus part escape gap 8 that absorbs the deformed volume is required. Therefore, as shown in FIGS. 4 and 5, at least one of the transparent resin thin film 5 and the front end of the ferrule 4 is formed with an excess portion relief gap 8 that allows the deformed volume to escape.
[0020]
The transparent resin thin film 5 is highly transparent so as not to reduce transmission loss, wets the surface of the optical fiber 3 when the optical fiber is joined, suppresses irregular reflection due to the irregular surface, and plays such as play of the engaging portion of the connection device. The material is preferably made of a material that elastically deforms and absorbs, and has a shear modulus of 5 × 10 ⁴ to 1 × 10 ⁷ Pa, preferably 1 × 10 ⁵ to 2 × 10 ⁶ Pa from the viewpoint of balance. Is good. This is because if the shear modulus is lower than this, the shape retention or adhesion to the sleeve 2 will be hindered. On the contrary, if it is higher than the range value, a large force is required when elastically deforming, unnecessary stress is applied to the connecting device, and further, distortion or the like occurs, and the joint becomes loose over time. Based on why.
[0021]
Examples of the material for the transparent resin thin film 5 include thermosetting resins such as silicone resins, urethane resins, epoxy resins, and diene resins, and heat such as thermoplastic elastomers such as ethylene-vinyl acetate copolymers, styrene, and olefins. A plastic resin. As the thermosetting resin, a liquid material can be selected, which is convenient because it is convenient for a small amount of shaping described later and has high adhesiveness. In addition, by adjusting the crosslinking density, the shear modulus can be adjusted relatively easily, and a large amount of plasticizer is not required for softening, which is preferable because it does not adversely affect the adhesiveness. In the shaping process, low viscosity is good, and 100 to 30000 cs is optimal.
[0022]
In addition, in order to improve the strength of the transparent resin thin film 5, as additives, reinforcing fillers such as silica fine particles and transparent resin fillers, adhesion promoters such as silane coupling, plasticizers, clearing agents and transparent elastic fine particles, A refractive index adjusting agent, a fluorine-based or silicone-based release agent for preventing the optical fiber 3 from sticking, and the like can be appropriately mixed. In particular, it is preferable to add an antistatic agent such as an ionic system so as to prevent the adsorption of dust and the like and not cause a transmission loss, so that the surface resistance of the transparent resin thin film 5 is 10 ⁵ to 10 ⁸ Ωcm.
When mixing these additives, it is important that the transparency is lowered by the mixing and that the transmission characteristics are not adversely affected.
[0023]
Among these, the silicone resin is particularly preferable because of transparency, environmental stability, workability, and a wide range of hardness adjustment. Silicone resins are mainly composed of diorganopolysiloxanes containing unsaturated groups such as alkenyl groups, and are cured by addition reaction using a platinum catalyst with organohydrogenpolysiloxane as a curing agent, or silanol group-containing organopolysiloxanes and Either a condensation reaction type using dibutyltin dilaurate or the like as a catalyst with an organopolysiloxane having a hydrolyzable group such as an alkoxy group or a ketoxime group may be used, but an addition reaction type is preferable in terms of adhesiveness. In addition, the condensation reaction type that does not require heat for curing is preferable in that the sleeve 2 is not strained by heat.
[0024]
For these, silane-treated silica fine particles and organopolysiloxane having a three-dimensional network resin structure are required as reinforcing fillers. In general, a resin structure having excellent transparency is preferably used in a region where the shear modulus is low, and silica particles can be used when strength is required in a high region. As the dispersion of the filler is higher, the transparency and refractive index are not adversely affected, and the strength can be improved.
[0025]
In order to improve the adhesion, in the addition reaction type, the number of moles of hydrogen atoms bonded to Si atoms of the organohydrogenpolysiloxane is increased by 2 to 5 times the number of moles of alkenyl groups, or Si atoms An organopolysiloxane having a hydrogen atom or an alkenyl group bonded to an epoxy group such as a glycidoxy group, an alkoxysilyl group such as a trimethoxysilyl group, a triethoxysilyl group, or a methyldimethoxysilyl group, an acrylic group, a methacrylic group, or an anhydrous carboxy group A mixture of an amino group or an amide group and an allyl ester derived from an acrylic ester or an unsaturated monohydric alcohol is preferable. In addition, as a promoter, silane coupling such as vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, etc. It is also possible to mix the agents.
[0026]
Oil-like organopolysiloxanes or modified products thereof may be mixed as a plasticizer component for adjusting the hardness or the like, but in addition to the function as a plasticizer, they bleed over time, and in particular the optical fiber 3 or Bleeding when pressurized by the ferrule 4 and forming a thin film on the interface with the optical fiber 3 brings about a mold release effect, prevents adhesion to the optical fiber 3 and the like, and further connects the optical fiber 3. This is preferable because it can get wet on the end face and suppress irregular reflection. Furthermore, in order to improve releasability, it is also possible to contain fluorine-containing groups such as 3,3,3-trifluoropropyl groups.
[0027]
The addition of antistatic properties is preferably an antistatic agent having compatibility with silicones, including organopolysiloxanes having a portion containing an ionic group such as an amine salt or a sulfonate. These modifying groups include primary amine salts, secondary amine salts, tertiary amine salts, quaternary ammonium salts, quaternary phosphonium salts as cationic groups, and sulfonic acids (salts) as anionic groups. Carboxylic acid (salt), sulfuric acid ester (salt), phosphoric acid ester (salt), and the like. In addition, polyoxyalkylene group, amino group, ferrule group, polyoxyalkyl ether fatty acid amide group, cyanoalkyl group, trifluoroalkyl group, epoxy group, carboxyl group and the like can be mentioned.
[0028]
The refractive index of the transparent resin thin film 5 is 1.3 to 1.6, and a material close to the optical fiber 3 is preferably selected. This adjustment can be performed by copolymerizing methylphenylsiloxane, diphenylsiloxane, fluorinated alkylsiloxane, stanosiloxane and the like.
[0029]
Next, a method for manufacturing an optical fiber connecting device will be described. First, a first mold that has been subjected to a mold release process having a desired shape is inserted from one of the open ends of the sleeve 2, and one of the sleeves 2 is closed so that the liquid material of the transparent resin thin film 5 does not flow out. The mold is preferably made of a material having a hardness lower than that of the sleeve 2 so that the inner wall of the sleeve 2 is not damaged. Specific examples include olefin resins, nylon resins, fluororesins, silicone resins and the like. In order to improve the sealing performance, it is possible to provide a brim-shaped seal portion or arbitrarily adopt an elastic material or the like.
[0030]
Next, the measured liquid material is injected with a precision dispenser or the like. The injection amount at this time is as small as approximately 0.03 to 7 nl and cannot be dropped, so the tip of the precision dispenser needle is brought close to the first mold and the liquid material droplet contacts the mold. Then, the needle can be released and the droplet can be transferred and provided. Of course, if necessary, a solvent can be added to increase the injection amount to improve the injection accuracy. At this time, it is necessary to sufficiently dry, and the initial liquid level height is the thickness of the outer peripheral portion 6 of the transparent resin thin film 5 described above, and the central portion 7 is a solvent solution, although it varies depending on the wet state with the inner wall of the sleeve 2. It becomes thinner with volatilization.
[0031]
Of course, if necessary, after injecting the liquid material, the second material can be inserted to shape the liquid material. If the mold is removed after the liquid material is cured or solidified, a connecting device in which the transparent resin thin film 5 is formed on the central portion 7 of the sleeve 2 is completed. When heating is required for curing, drying, melting or the like of the liquid material, it is preferable to perform the heating in a temperature range in which the dimensional stability of the sleeve 2 or the like is maintained. Further, if necessary, a primer for promoting adhesion can be provided on the bonded portion of the sleeve 2 by dip coating or the like.
[0032]
Next, a method for connecting the optical fiber 3 will be described. First, the coating on the end of the optical fiber 3 is peeled off and inserted into the ferrule 4, and the excess portion of the optical fiber 3 protruding from the tip of the ferrule 4 is removed. If necessary, the connecting end face of the optical fiber 3 is pressed against a hot plate and mirror-finished to obtain the optical fiber 3 with the ferrule 4. When the optical fiber 3 with the ferrule 4 is thus obtained, the connection can be completed by inserting the optical fiber 3 into a connecting device and then locking it.
[0033]
According to the above configuration, since the transparent resin thin film 5 is bonded and integrated with the straight tubular sleeve 2, the optical fiber 3 can be easily inserted and removed, and the shift of the optical axis can be minimized. Moreover, since it can be performed with low stress, a stable state can be maintained over time. Moreover, since adhesion of dust or the like can be prevented, the optical fiber 3 with a small transmission loss can be joined, and optical communication can be used easily and easily in daily life. Further, since the transparent resin thin film 5 can be easily shaped, the productivity is remarkably improved, which is extremely effective in the industry.
[0034]
In addition, although the optical fiber 3 and the ferrule 4 shown in FIG. 4 were shown in the said embodiment, it is not limited to this at all. For example, the tip portions of the optical fiber 3 and the ferrule 4 can be appropriately changed to the shapes shown in FIGS. Specifically, the outer periphery of the tip of the ferrule 4 can be cut out to form a step, or the connecting end face of the optical fiber 3 can be cut obliquely to form the tip of the ferrule 4 in a substantially hollow truncated cone shape. Also, the transparent resin thin film 5 can be appropriately changed to the shape shown in FIGS.
[0035]
【The invention's effect】
As described above, according to the present invention, it is possible to utilize the simplicity of processing that is a feature of an optical fiber made of plastic, and it is possible to easily join optical fibers made of plastic. Further, since the antistatic treatment is performed on the transparent resin thin film, it is possible to prevent the adsorption of dust and the like and prevent transmission loss.
[Brief description of the drawings]
FIG. 1 is an explanatory perspective view showing an embodiment of an optical fiber connecting device according to the present invention.
FIG. 2 is a schematic cross-sectional explanatory view showing an embodiment of an optical fiber connecting device according to the present invention.
3 is an enlarged cross-sectional view of a main part of FIG.
FIG. 4 is a schematic cross-sectional explanatory view showing the tip portion of the optical fiber and ferrule in the embodiment of the optical fiber connecting device according to the present invention.
FIG. 5 is a schematic explanatory view showing a transparent resin thin film in an embodiment of an optical fiber connecting device according to the present invention.
FIG. 6 is a schematic cross-sectional explanatory view showing the optical fiber and the tip of a ferrule in the second embodiment of the optical fiber connecting device according to the present invention.
FIG. 7 is a schematic cross-sectional explanatory view showing an optical fiber and a tip portion of a ferrule in a third embodiment of an optical fiber connecting device according to the present invention.
FIG. 8 is a schematic cross-sectional explanatory view showing the optical fiber and the tip of a ferrule in a fourth embodiment of an optical fiber connecting device according to the present invention.
FIG. 9 is a schematic explanatory view showing a transparent resin thin film in a fifth embodiment of an optical fiber connecting device according to the present invention.
FIG. 10 is a schematic explanatory view showing a transparent resin thin film in a sixth embodiment of an optical fiber connecting device according to the present invention.
FIG. 11 is a schematic explanatory view showing a transparent resin thin film in a seventh embodiment of an optical fiber connecting device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Case 2 Sleeve 3 Optical fiber 4 Ferrule 5 Transparent resin thin film 6 Outer peripheral part 7 Central part (substantially central part)
8 Excessive part clearance gap

Claims (5)

An optical fiber connecting device comprising a sleeve, a plurality of plastic optical fibers inserted into the sleeve and opposed to each other, and a ferrule fitted into the opposing portion of each optical fiber and inserted into the sleeve,
Inside the sleeve, the transparent resin thin film positioned between the plurality of optical fibers opposing provided, along with the range of the shear modulus of the transparent resin film ^{5 × 10 4 ~1 × 10 7} Pa, the transparent resin An optical fiber connecting device characterized in that an antistatic treatment is applied to a thin film .   2. The optical fiber connecting device according to claim 1, wherein at least one of the ferrule and the transparent resin thin film is formed with an excess portion relief gap for the transparent resin thin film deformed by being sandwiched between the plurality of optical fibers.   3. The optical fiber connecting device according to claim 1, wherein the transparent resin thin film is formed in a substantially disc shape, and the thickness of the adhesion region at the outer peripheral portion thereof is made thicker than the thickness of the substantially central portion.   The optical fiber connecting device according to claim 3, wherein the thickness of the substantially central portion of the transparent resin thin film is 0.05 to 0.5 mm.   5. The optical fiber connecting device according to claim 1, wherein the transparent resin thin film is an organopolysiloxane.

Images