JPH11167031A - Plastic multi optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic multi optical fiber cable which is small in loss when bent at a small radius of bending, is small in rigidity and is excellent in flexibility. SOLUTION: This plastic multi optical fiber cable is constituted by providing the outer peripheries of plastic multi optical fibers constituted by arranging 3 to 3240 pieces of light transmittable core parts of 20 to 300 μm in diameter in the sea part of the fiber having a circular section of 0.2 to 2 mm in diameter with resin coating layers. The area occupying rate of the resin coating layers is 40 to 95% in section of the cable and the light quantity when the fibers are wound once around a rod of 1 mm in radius maintains >=90% of the light quantity when the fibers are not wound around the same and the modulus E of elasticity in bending is <=350 MPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic multi-optical fiber cable having excellent flexibility used in fields such as a photoelectric sensor, a light guide, an image transmitter, and a communication.

[0002]

2. Description of the Related Art An optical fiber used in a photoelectric sensor is generally used by bundling one or more single-core optical fibers having an optical transmission property. The fiber has a problem that bending loss is large when bending with a small bending radius. JP-A-5-40180 discloses a sensor unit using an optical fiber that can be bent with a radius of about 5 mm as a plastic optical fiber that improves the problem of the bending loss. According to the publication, a plastic optical fiber having a small bending loss and a cable thereof are disclosed.

However, since the bending rigidity is not considered in the sensor unit, the plastic optical fiber, and the cable thereof, it is difficult to lay the sensor unit in a case where it is bent at substantially right angles along a wall. .

[0004]

SUMMARY OF THE INVENTION The present inventors have conducted various studies to solve these problems, and as a result, specified the structure of an optical fiber and a coating material called a jacket material.
By keeping the flexural modulus below a specific value, it is possible to obtain a plastic multi-optical fiber cable that has a small loss when bent at a small bending radius, is flexible, has low rigidity, and is easy to bend at right angles. Have found the present invention. An object of the present invention is to provide a plastic multi-optical fiber cable which has a small loss when bent at a small bending radius, and has a small rigidity and excellent flexibility.

[0005]

According to the present invention, a diameter of 0.2 to 0.2 mm is provided.
The diameter of the fiber is 20 to 300 mm at the sea part of the fiber having a circular cross section of 2 mm.
This is a multi-optical fiber cable in which a resin coating layer is provided on the outer periphery of a plastic multi-optical fiber in which 3 to 3240 μm optical transmission cores are arranged, and the area occupancy of the resin coating layer in the cable cross section Is 40-95%,
A plastic multi-optical fiber cable characterized in that the light quantity when wound once around a rod having a radius of 1 mm holds 90% or more of the light quantity when not wound, and the flexural modulus E is 350 MPa or less. .

[0006]

DETAILED DESCRIPTION OF THE INVENTION A plastic multi-optical fiber cable of the present invention (hereinafter referred to as an optical fiber cable).
Has a resin coating layer on the outer periphery of a plastic multi-optical fiber (hereinafter, referred to as an optical fiber) having a structure in which a large number of cores are present in a sea portion, and the entire fiber has a circular shape having a diameter of 0.2 to 2 mm. Is provided. The core portion of the optical fiber located in the sea has optical transmission properties, and the optical transmission core having a diameter of 20 to 300 μm is 3 to 32 μm.
Forty are arranged. Optical fiber cross section diameter is 2m
When the diameter exceeds m, rigidity increases and compatibility with the conventional optical fiber is lost. When the diameter is less than 0.2 mm, not only does the optical transmission performance decrease, but also the required number of cores is formed. Becomes difficult.

In the optical fiber cable of the present invention,
The occupation ratio of the resin coating layer in the cable cross section is 40 to 95%
Range.

In the optical fiber used for the optical fiber cable of the present invention, the core and the sea are formed of different resins, respectively, and a sheath layer or a core formed of another resin is provided at the boundary between the core and the sea. And a compatible part of the sea part may be formed. In addition, a protective layer made of a resin different from the sea part or the same resin as the sea part may be provided on the outer peripheral part of the sea part where a number of core parts are present, and providing the protective layer may damage the core part near the outer peripheral part. This is preferable to prevent.

The core of the optical fiber has a diameter of 20 to
If it is 300 μm, it is not necessarily required to be circular, and it may be polygonal such as hexagon. As for the arrangement of the cores in the optical fiber, it is preferable that the cores covered with the sea component be packed in a bale-stack shape so that the outer shape becomes almost circular. If the ratio of the total cross-sectional area of the core to the fiber cross-sectional area is large, the core near the outer periphery of the fiber has a significantly different shape from the core at the center, which may cause a decrease in optical transmission performance. It is preferable to arrange the core so that the core near the outer periphery of the fiber is located at a distance of 5 to 50 μm from the outer periphery of the fiber, or to provide a protective layer on the outer periphery of the sea.

The optical fiber cable of the present invention has a radius of 1 m.
The light amount when wrapped once around the rod of m holds 90% or more of the light amount when not wrapped, and 350 MPa or less,
Preferably, it has a flexural modulus E of 300 MPa or less. The flexural modulus of an optical fiber cable is mainly determined by the flexural modulus of the resin constituting the resin coating layer and the occupancy of the area of the resin coating layer in the cable cross section. The lower the flexural modulus of the resin constituting the resin coating layer, the lower the flexural modulus of the cable, and the higher the occupancy of the resin coating layer in the cable cross section, the lower the flexural modulus of the cable.

The flexural modulus E is determined by setting the optical fiber cable to a span width L ₀ = 30 mm and applying a load W to the center.
It is calculated from the relationship between the load and the amount of deflection y at the center by the following equation. Flexural modulus E (MPa) = W · 4L 0 3 / (y · 3π
D ⁴ ) (However, D: diameter (m))

In the optical fiber cable of the present invention, the color of transmitted light is emphasized in the case of image transmission, but the amount of light that can be transmitted is emphasized in other communication applications.
An index F value represented by the following formula indicating an average light amount that can be transmitted per unit area in a 4 m long optical fiber cable is 1 ×
It is preferably 10 ^-1 or more. F = S · NA ² · 10 ^{− (L ·} α ^{/ 10)} (where S: fiber cross-sectional area S in optical fiber cross-section ⁾
Ratio S ₁ / S ₀ of core cross-sectional area S ₁ to ₀ , NA: numerical aperture of optical fiber, α: transmission loss of optical fiber (dB / k)
m), L: optical fiber length (m))

Further, the optical fiber cable of the present invention may have the above characteristics, one or more curls having an inner diameter of 2 to 20 mm, and the emitted light amount In may satisfy the following conditions. In ≧ I ₀ × 0.9 ⁿ (where n: number of curls, I ₀ : initial emitted light amount) The initial emitted light amount I ₀ is such that a predetermined amount of light is incident from one end of an optical fiber having a predetermined length. Sometimes, it is the amount of light emitted from the other end. The outgoing light amount In is the outgoing light amount measured under the same conditions as the initial outgoing light amount with the optical fiber curled.

The use of the optical fiber cable of the present invention is not particularly limited, and it can be used in all fields using optical fibers such as photoelectric sensors, light guides, and image transmission bodies. Fiber diameter, diameter and number of cores, core, sea or protective layer, and constituent material of resin coating layer are appropriately determined.

In the production of the optical fiber cable of the present invention, for example, a clean core component and a sea component are prepared, and the nozzle holes corresponding to the number of core portions are arranged in a close-packed arrangement so that the outer shape becomes substantially circular. A plurality of core-sea structures are formed by supplying and discharging the core component and the sea component to the spinning nozzle arranged in the above, and forming the plurality of core-sea structures simultaneously with or after the formation of the core-sea structure. Integrated, and if necessary, covered with a protective layer,
It is performed by stretching. For example, in the case of an optical fiber having an outer diameter of 1 mm, if the number of cores is 18 to 300, an optical fiber having a core of 50 to 200 μm in diameter can be manufactured.

The cable may be manufactured by coating the outer periphery of the optical fiber with a resin at the same time as the spinning at the time of manufacturing the optical fiber, or by coating the outer periphery of the optical fiber with the resin by any known means in another process after the manufacture of the optical fiber. Performed by Resin has an area occupancy of 40 to 95% of the resin coating layer in the cable cross section.
The outer periphery of the optical fiber is coated so that For example, when resin is coated on an optical fiber having an outer diameter of 1 mm so that the outer diameter of the cable becomes 2.2 mm, the area occupation ratio of the resin coating layer in the cable cross section is about 79%.

In the production of the optical fiber, the plurality of core-sea structures may be integrated by bringing the respective nozzle holes to be discharged into the core-sea structure close to each other and discharging them in a converged state. The core-sea structure may be brought into close contact with each other by using a base or a funnel-shaped base.

The stretching at the time of manufacturing the optical fiber is performed after forming the optical fiber or after forming the protective layer, but can also be performed after forming the resin coating layer. The stretching ratio is determined in a range of 1.2 to 4 times so as to satisfy necessary optical characteristics and mechanical characteristics. For the purpose of heating and cooling the optical fiber, it can be passed through a liquid in the spinning or drawing step.

As the core component of the optical fiber, various highly transparent resins used in known optical fibers are used, and various resins such as styrene-based, polycarbonate-based, and methyl methacrylate-based resins are exemplified. Particularly preferred resins include a methyl methacrylate homopolymer and a copolymer containing benzyl methacrylate as a main component.

Examples of the sea component include methyl methacrylate resin, methyl acrylate resin, vinylidene fluoride resin, and tetrafluoroethylene resin having a lower refractive index than the core component. Homopolymer of 2-trifluoroethyl methacrylate, polyvinylidene fluoride (2F) / tetrafluoroethylene (4
F) Copolymer, 2,2,3,3,3-pentafluoropropyl methacrylate (5FM) / 1,1,2,2-tetrahydroxyperfluorodecyl methacrylate (1
7FM) / methyl methacrylate (MMA) / methacrylic acid (MAA) copolymer, trifluoroethyl methacrylate / 17FM / MMA / MAA copolymer and the like are preferably used. As the protective layer component, the above-mentioned core component,
The same resin as the marine component is used.

The resin of the resin coating layer is selected so that the flexural modulus of the optical fiber cable is 350 MPa or less, and various thermoplastic resins having a flexural modulus of the resin of 350 MPa or less are preferably used. Particularly preferred resins include vinyl chloride polymers or blends containing vinyl chloride polymers, low density polyethylene, linear low density polyethylene, chlorinated polyethylene, ethylene / vinyl acetate copolymers, vinyl chloride polymers and ethylene. / Vinyl acetate copolymer, polyurethane resin, etc., and particularly, a vinyl chloride polymer, and a blend of a vinyl chloride polymer and an ethylene / vinyl acetate copolymer are preferably used. In addition, these resins, thermosetting resins, photocurable resins, and various shape memory resins can also be used.
Alternatively, these resins containing metal fine powder, metal short fiber, and metal long fiber are also used.

A plasticizer may be added to the resin of the resin coating layer. However, it is necessary to select a plasticizer that avoids migration to the optical fiber and adversely affecting the optical performance and mechanical properties of the optical fiber. Is preferred. Further, the optical fiber cable of the present invention can be provided with a curl, and when a cable having a curl is formed, a curl having an inner diameter of 2 to 20 mm or two or more continuous curls is formed by a known method. can do.

[0023]

The present invention will be described below in more detail with reference to examples.

Example 1 Polymethyl methacrylate was used as the core component, and vinylidene fluoride / tetrafluoroethylene copolymer was used as the sea component and the protective layer component.
Using a spinning nozzle in which 51 nozzle holes are arranged in a close-packed arrangement so that the outer shape becomes a substantially circular shape, the spinning nozzle is stretched and has an outer diameter of 1 having 151 light transmitting cores having a diameter of 75 μm. A plastic multi-optical fiber of 0.0 mm was obtained.
A vinyl chloride polymer and ethylene /
Blend of vinyl acetate copolymer (Toyo Ink Co., Ltd., 3
14) to obtain an optical fiber cable having an outer diameter of 2.2 mm. The area occupancy of the resin coating layer in the cross section of the optical fiber cable was 79.3%.

This optical fiber cable was cut into a length of 5 m, and the light quantity when the center part of the cable was wrapped once around a rod having a radius of 1 mm was measured with light having a NA of 0.1 and a wavelength of 650 nm. , And 99.5% of the light amount was maintained, and there was almost no decrease in the light amount due to the winding. This optical fiber cable has a flexural modulus E of 210
When the stiffness is low at MPa and it is attempted to lay along a right-angled corner, the resin of the resin coating layer is deformed, so it is easy to lay without leaving a gap between the corner and the optical fiber cable. Met. At this time, the bending radius of the optical fiber in the optical fiber cable was about 0.5 mm.

Example 2 The same resin as in Example 1 was used for the core component, the sea component, and the protective layer component, and 37 optically transmissive cores having a diameter of 75 μm were formed in the same manner as in Example 1. A plastic multi-optical fiber having an outer diameter of 0.5 mm was obtained. The outer periphery of this optical fiber was coated with a blend of a vinyl chloride polymer and an ethylene / vinyl acetate copolymer (314, manufactured by Toyo Ink Co., Ltd.) to obtain an optical fiber cable having an outer diameter of 1 mm. The area occupancy of the resin coating layer in the cable cross section in this optical fiber cable was 75%. The optical fiber cable was cut into a length of 5 m, and the light amount when the center portion of the cable was wound once around a rod having a radius of 1 mm was measured with light having a NA of 0.1 and a wavelength of 650 nm. It was 77% or more. Further, the bending elastic modulus E of the optical fiber cable was 150 MPa, and it was easy to lay along the right-angled corner without leaving a gap between the corner and the optical fiber cable.

Comparative Example 1 Polymethyl methacrylate was used as the core component, vinylidene fluoride / tetrafluoroethylene copolymer was used as the sea component, and the outer diameter was 1.0 mm.
Was obtained. The outer periphery of the single-core optical fiber was coated with high-density polyethylene to obtain an optical fiber cable having an outer diameter of 2.2 mm. The area occupancy of the resin coating layer in the cross section of the optical fiber cable was 79.3%.

This optical fiber cable was cut into a length of 5 m, and the light quantity when the center part of the cable was wrapped once around a rod having a radius of 1 mm was measured with light having a NA of 0.1 and a wavelength of 650 nm. This optical fiber cable had a flexural modulus E of 400 MPa, a high rigidity, and was difficult to lay at right angles.

Comparative Example 2 Using a polymethyl methacrylate as a core component and a vinylidene fluoride / tetrafluoroethylene copolymer as a sea component, a light transmitting core having a diameter of 66 μm was produced in the same manner as in Example 1. A plastic multi-optical fiber having an outer diameter of 1.13 mm and having 217 pieces was obtained. The outer periphery of the optical fiber was coated with low-density polyethylene to obtain an optical fiber cable having an outer diameter of 2.2 mm.
The area occupancy of the resin coating layer in the cable cross section in this optical fiber cable was 73.6%.

When this optical fiber cable was cut into a length of 5 m and the center of the cable was wrapped once around a rod having a radius of 1 mm, the amount of light was measured with light having a NA of 0.1 and a wavelength of 650 nm. This optical fiber cable has a flexural modulus E of 43%.
At 0 MPa, the rigidity was large, and it was impossible to lay at a right angle.

[0031]

The plastic multi-optical fiber cable of the present invention has a small loss when bent at a small bending radius, and has a small rigidity and excellent flexibility. The plastic multi-optical fiber cable of the present invention has a small bending loss and excellent flexibility, so it is excellent in handleability, and can be bent at a right angle, laid or formed into a curled cord, and the like. It is suitably used in fields such as sensors, light guides, image transmitters, and communications.

Claims (3)

[Claims] 1. An optical transmission core having a diameter of 20 to 300 μm is provided at a sea portion of a fiber having a circular cross section having a diameter of 0.2 to 2 mm.
A multi-optical fiber cable in which a resin coating layer is provided on the outer periphery of a plastic multi-optical fiber in which ~ 3240 pieces are arranged, wherein the area occupancy of the resin coating layer in the cable cross section is 40 to 95%, and the radius is 1 mm. A multi-optical fiber cable made of plastic, characterized in that the light quantity when wound once around the rod is 90% or more of the light quantity when not wound, and the flexural modulus E is 350 MPa or less. 2. The plastic multi-optical fiber cable according to claim 1, wherein the resin of the resin coating layer is a vinyl chloride polymer or a blend of a vinyl chloride polymer and an ethylene / vinyl acetate copolymer. 3. The multi-optical fiber cable according to claim 1, wherein the cable has at least one curl having an inner diameter of 2 to 20 mm, and an emitted light amount In satisfies the following condition. Fiber cable. In ≧ I ₀ × 0.9 ⁿ (n: number of curls, I ₀ : initial emission light amount)