JPH06118285A - Optical fiber coated fiber and pressure sensor using optical fiber coated fiber - Google Patents

Abstract

PURPOSE:To provide an optical fiber coated fiber having incombustibility and UV radiation resistance and excellent in the bending property in all directions when multiple optical fibers are used in a lump by providing a thin backing metal layer on the periphery of the optical fiber coated with a ultraviolet hardening resin on an optical fiber constituted of a core and a clad. CONSTITUTION:An optical fiber 2 constituted of a core and a clad is used for this optical fiber coated fiber, and a UV hardening resin layer 3 is provided on the fiber 2. A preform in the fused state is generally wire-drawn, concurrently UV-coated, immediately hardened, and resin-coated to form the UV hardening resin. A liquid resin hardened by UV radiation such as epoxy acrylate or urethane acrylate is used for the raw material of the UV hardening resin layer 3. The UV hardening resin layer 3 has low conductivity, no electroplating can be directly applied, and a backing metal layer 4 is provided on the UV hardening resin layer 3. A surface metal layer 5 is efficiently formed on it by electroplating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber core wire which is flame-retardant and has a large bending strength as compared with an optical fiber element wire coated only with an ultraviolet ray (hereinafter referred to as UV) curable resin.
The present invention relates to a pressure sensor that uses an optical fiber tape and a metal-coated optical fiber core wire that have excellent flexibility when used together.

[0002]

2. Description of the Related Art In order to protect the surface of a quartz optical fiber, a molten preform is drawn and at the same time a liquid plastic resin is coated and immediately cured. As a resin curing means, there are a method of heating an ordinary plastic resin and baking it, and a method of irradiating a UV curable resin with UV. At present, however, since the curing speed is fast, most of the UV curable resin is used. There is.

An optical fiber coated with a UV curable resin is not only laid between communication facilities at room temperature, but is often wired near an OA device in a high temperature state, for example, a CPU that generates heat at a high clock speed. In the thyristor used for the high-voltage AC to DC converter, the firing optical fiber must have heat resistance. Further, if an optical fiber tape capable of withstanding higher temperatures than the current situation is proposed, it is expected to be used for wiring around the high temperature furnace and measurement.

[0004]

The optical fiber core wire coated with the UV-curable resin is flammable in the UV-curable resin. Therefore, the optical fiber core wire may be wrapped with a heat shield tape or a heat absorbing material may be added to the plastic sheath. However, the heat resistance of the cable cannot be sufficiently increased. In addition, the use of the optical fiber alone has a defect that its application is limited because the resin deteriorates with time due to the UV of the fluorescent lamp. Therefore, instead of coating the optical fiber with a UV curable resin, it has been proposed to apply molten metal at the same time as drawing the preform, or to form a metal film on the fiber surface immediately after drawing by plating or vapor deposition. ing.

An optical fiber core wire in which an optical fiber is directly coated with a metal is preferable for heat resistance and fire resistance as the metal coating layer is thicker, but the metal coating layer should be thicker to obtain sufficient heat resistance and mechanical strength. For example, since the growth rate of plating or vapor deposition is slow, it takes a lot of time and cost to form a metal film. Moreover, if the metal coating becomes thick to some extent, the flexibility of the optical fiber core wire is relatively lowered, and the laying work becomes very difficult.

Further, as illustrated in FIG. 4, in a known optical fiber tape 10 having a multi-core structure of 4 to 8 cores, a primary resin layer 12 is individually formed on a plurality of optical fibers 11,
After arranging the resin-coated fiber core wires in a horizontal row, a secondary resin layer 13 that surrounds the whole is further formed. The optical fiber tape 10 having a flat cross section as shown in the figure is considerably difficult to bend in the horizontal direction of the arrow A, which makes the work extremely difficult when wiring inside narrow equipment such as OA equipment.

As a result of various studies on the heat resistance of the optical fiber core wire, the present inventors have found that
If a thin metal layer is coated on the curable resin layer, the heat resistance and bending strength of the optical fiber core wire will rise considerably even if the metal layer is thin, and the original flexibility of the optical fiber will not be lost. Was discovered. Therefore, an object of the present invention is to provide an optical fiber core wire which is flame-retardant and resistant to UV irradiation, as compared with an optical fiber element wire which is only coated with a UV curable resin.

Another object of the present invention is to provide an optical fiber tape having excellent flexibility in all directions when a plurality of the above-mentioned optical fiber core wires are used together. Another object of the present invention is to provide a pressure sensor which is free from electromagnetic noise by using a metal-coated optical fiber core wire.

[0009]

In order to achieve the above object, an optical fiber core wire 1 according to the present invention uses an optical fiber 2 composed of a core and a clad as shown in FIG. A UV curable resin layer 3 is provided. This UV
The curable resin generally draws a molten preform, and at the same time, UV-coats it and immediately cures it. The diameter of the resin-coated optical fiber core wire is about 200 to 400 μm.

The material of the UV curable resin layer 3 is a liquid resin such as epoxy acrylate or urethane acrylate that is cured by UV irradiation. Alternatively, the molten preform may be drawn and then coated with amorphous carbon or the like in a reaction furnace. Finally, liquid UV
A curable resin is coated and cured.

Since the UV curable resin layer 3 has low conductivity and cannot be directly electroplated, the base metal layer 4 is first provided on the UV curable resin layer. The underlying metal layer 4 is provided relatively thinly and uniformly on the peripheral surface of the optical fiber, and the underlying metal layer is formed by electroless plating, vacuum deposition, sputtering,
It may be formed by any of the ion plating methods. The base metal layer 4 may have a thickness of several μm or less, and its material is, for example, copper, nickel, aluminum, silver, gold or the like.

Further, the surface metal layer 5 may be efficiently formed by an electroplating method. Although the surface metal layer is usually thicker than the base metal layer 4, the flame retardance of the optical fiber core wire 1 is 2 to 20 μm. To achieve and maintain its flexibility. The material of the surface metal layer 5 is copper, nickel, aluminum, silver, gold, etc., like the base metal layer 4.

In the optical fiber core wire, after the base metal layer 4 and the surface metal layer 5 are further formed, a solder layer 9 (FIG. 3) having a thickness of 1 to 5 μm may be further formed on the surface.
The solder layer 9 may be efficiently formed by electroplating.

In the optical fiber tape 6 shown in FIG. 2, a plurality of optical fiber core wires 1 are used, and the plurality of optical fiber core wires 1 are usually spaced at intervals of about 10 to 15 cm and the soldering layer 7 is used.
Alternatively, it is bound with an adhesive. The number of the optical fiber core wires 1 to be bundled may be arbitrarily selected, and the number is generally 4 to 10.

Although not shown, the optical fiber core wire 1 of the present invention can be used as a pressure sensor. In this case, it suffices to dispose the optical fiber core wire 1 on a plane and connect the light source to one end and the light receiving portion to the other end, so that the pressure is perpendicular to the axis of the optical fiber core wire. Apply to.

Further, another example of the pressure sensor is shown in FIG. 5, and in the pressure sensor 15, the optical fiber core wire 1 is connected to the elastic cylindrical body 1.
A light source 1 is wound around 6 and is attached to one end of the optical fiber core wire.
A light receiving portion 18 is coupled to 7 and the other end. In order that the pressure to be measured can be applied to the outer circumference of the elastic cylindrical body 16, an appropriate pressure receiving member 19 may be installed so as to contact with the upper or side of the optical fiber core wire 1 on the outer circumference of the cylindrical body.

[0017]

In the optical fiber core wire 1 according to the present invention, even if the UV curable resin layer 3 is flammable, by forming the metal layers 4 and 5 on the outside, compared with the optical fiber bare wire having only the resin coating. It is flame-retardant, has greater flexural strength, and has UV irradiation resistance. Metal layers 4, 5 formed on the outside
Since the relatively soft UV curable resin layer 3 is present inside, the heat resistance can be sufficiently improved even if it is relatively thin, and the flexibility of the optical fiber core wire 1 is hardly impaired.

The optical fiber core wire 1 on which the metal layers 4 and 5 are formed is easier to solder than the optical fiber bare wire coated only with the resin. In the optical fiber tape 6, if the plurality of optical fiber core wires 1 are bound by the soldering layer 7 at intervals of about 10 to 15 cm, the optical fiber tape 6 is easily bent in any direction, as shown in FIG. Flexibility is superior to that of the optical fiber tape 10 having a flat cross section.

When the optical fiber core wire 1 is used as a pressure sensor, pressure is applied at a right angle to the axis of the optical fiber core wire 1 by arranging the optical fiber core wire on a plane, and the core / clad of the optical fiber core wire is applied. Change the refractive index of. The value of the applied pressure can be measured by measuring the change in the amount of passing light due to this change.

In the pressure sensor 15 shown in FIG. 5, the radius of curvature of the elastic cylindrical body 16 is changed by the pressure applied from the upper side or the side, and the optical fiber core wire 1 is caused to correspond to this change to induce the macrobend. To do. The value of the applied pressure can be measured by measuring the change in the amount of light passing through the optical fiber core wire 1 during macrobending.

[0021]

EXAMPLES Next, the present invention will be explained based on examples. Example 1 Using a silica-based optical fiber 2 having a diameter of 125 μm, a preform was heated to about 2000 ° C. in an electric furnace (not shown) to melt and draw at a stretch, and at the same time, an epoxy acrylate that was cured by UV irradiation was coated. Immediately cured by UV, the diameter of the optical fiber strand is set to 230 μm. This optical fiber element wire is immersed in a cleaning tank and washed with water, immersed in an etching tank with water, and immersed in an activator tank with water.

The electroless nickel plating provided on the UV curable resin layer 3 is Ni-B plating / BEL 801 (manufactured by Uemura Kogyo Co., Ltd.), which is dimethylamine borane (DMA).
The base nickel layer 4 having a thickness of about 0.5 μm is provided by immersing in a bath containing B) as a reducing agent at 65 ° C. for 3 to 5 minutes. The obtained nickel-coated optical fiber element wire is further washed with water and hot water, and then dried.

Next, an optical fiber wire coated with a nickel base is vertically placed in an electrolytic plating bath having the following bath composition, and nickel is coated as a surface metal at a bath temperature of 50 ° C. Nickel sulfamate 300 to 700 g / liter Boric acid 30 g / liter Additives (brightener, pit preventive) Appropriate amount

As a result, the thickness of the nickel layers 4 and 5 of the optical fiber core wire 1 becomes 10 μm in total. The obtained optical fiber core wire 1 hardly deteriorates the UV curable resin layer 3 due to UV even if it is wired in an environment where it is illuminated by a fluorescent lamp, and is more difficult than an optical fiber bare wire coated only with resin. Reliable because it is flammable.

Example 2 An optical fiber preform is treated in the same manner as in Example 1 to obtain a 230 μm diameter optical fiber element wire whose surface is UV-coated with epoxy acrylate. In the same manner as in Example 1, the resin-coated optical fiber element wire is electroless plated to provide the underlying nickel layer 4 having a thickness of 0.5 to 1 μm.

Next, an optical fiber element wire coated with a nickel undercoat is immersed in an electrolytic plating bath having the following bath composition, and copper is coated as a surface metal layer at a bath temperature of room temperature. Copper sulphate 200-250g / l Sulfuric acid 20-75g / l Additive (brightener) Appropriate amount

As a result, in the obtained optical fiber core wire 1, the nickel layer 4 and the copper layer 5 coated on the surface increase the outer diameter by 12 μm. JIS-C-3005 rubber
Based on the test method of the plastic insulated wire, the flame retardance of the optical fiber core wire 1 is examined by a horizontal test. Length 300 mm
When the optical fiber core wire 1 of is supported horizontally and the tip of the reducing flame is applied to the lower side of the central part of the core wire until it burns within 30 seconds,
It quickly disappears within a few seconds of the start of combustion, and it is revealed that the flame retardancy is high.

Example 3 The optical fiber core wire 1 produced in Example 1 was dipped in an electrolytic plating bath having the following bath composition, and had 7% lead and 93% tin at a current density of about 10 to 15 A / dm ^2. Apply semi-bright solder plating. Stannous borofluoride 300 g / liter Lead borofluoride 50 g / liter Free borofluoric acid 200 g / liter Semi-brightener 20 ml / liter Dispersant 15 g / liter

In the optical fiber core wire 8 shown in FIG. 3, a solder layer 9 having a thickness of 2 μm is further formed on the surfaces of the metal layers 4 and 5. Since the solder layer 9 is formed on the surface, the optical fiber core wires 8 can be easily bundled by simply heating a plurality of them together, and can be easily attached to a metal wall of an OA device or the like.

Example 4 Four optical fiber core wires 1 produced in Example 2 are used, and all of these fiber core wires 1 are cut to a length of 1 m. As shown in FIG. 2, four optical fiber core wires 1 are put together and soldered on the entire surface at a distance of 10 cm by an ordinary method.

As a result, the optical fiber tape 6 in which the four optical fiber core wires 1 are bound by the soldering layer 7 is obtained. The optical fiber tape 6 is easily bent in any direction and can be freely bent even in a narrow device such as an OA device, so that the wiring work is facilitated.

Example 5 In the pressure sensor 15 shown in FIG. 5, the single-mode optical fiber core wire 1 obtained in Example 1 has an inner diameter of 8 mm and an outer diameter of 1 mm.
Wrap around the 0 mm synthetic rubber cylinder 16 three times.
The light source 17 coupled to one end of the optical fiber core wire 1 has λ = 8
A 50 nm LED, which measures the change in the amount of passing light in the light receiving portion 18 coupled to the other end of the optical fiber core wire 1.
The pressure receiving member 19 for applying a pressure to be measured is composed of a plate 20 in contact with an upper portion of the optical fiber core wire 1 on the outer circumference of the cylindrical body, and the plate is stably supported by a plurality of springs 21 in parallel with the cylindrical body 16.

In the pressure sensor 15, the position of the plate 20 is changed through the displacement of the spring 21 due to the applied pressure, and the synthetic rubber cylinder 16 and the optical fiber core wire 1 are deformed. That is, the radius of curvature of the synthetic rubber cylindrical body 16 is changed by the applied pressure, and the macrobend is induced by making the optical fiber core wire 1 wrapped around this change correspond to the amount of light passing through the optical fiber core wire 1 at this time. To measure the change in.

The input / output characteristic of the pressure sensor 15 is that the output voltage is about 1 to 5 when the applied pressure is 0 to about 0.3 Kgf / cm ³ .
It changes linearly with V, and the input and output are almost the same value. As a result, at an applied pressure of 0 to about 0.3 Kgf / cm ³ , the applied pressure can be accurately measured by utilizing the macrobend effect of the optical fiber core wire 1.

The suitability of the optical fiber core wire 1 as a pressure sensor is compared with other materials. In Table 1 below, MCUVF: optical fiber core wire 1 of the present invention, MCF:
These are metal-plated optical fiber strands, UVF: optical fiber strands coated with UV curable resin, and SIF: optical fiber strands coated with silicon resin.

[0036]

[Table 1]

From Table 1 above, it was found that the optical fiber core wire 1 (resin layer of about 10 μm) of the present invention having a thin resin layer and the metal-plated optical fiber element wire have suitability for pressure sensors. To do. On the other hand, the optical fiber element coated with UV curable resin is not suitable for pressure sensor even if the resin layer is thinned, and the optical fiber element coated with silicone resin has a resin layer of about 50 μm. It is not suitable for pressure sensors, and the resin layer cannot be made thinner.

[0038]

EFFECTS OF THE INVENTION The optical fiber core wire according to the present invention is flame-retardant as compared with an optical fiber bare wire coated only with a UV-curable resin by forming a metal layer on the coating resin layer even if the coating resin layer is flammable. However, the bending strength is even greater, and the optical fiber is not easily damaged or broken during the wiring work. The optical fiber core wire of the present invention becomes even more fire resistant and heat resistant if it is pressed and wrapped with a heat shield tape or a heat absorbing material is added to the plastic sheath, and even if the inside of the device becomes hot when used for internal wiring. Does not burn.

The optical fiber core wire of the present invention is UV
Even if it is coated with a curable resin, it has UV irradiation resistance, and even if it is wired in an environment where it is illuminated by a fluorescent lamp, the coating resin layer is less likely to deteriorate due to UV. In the optical fiber core wire of the present invention, since the surface metal layer is not so thick, it does not require a great deal of time and cost for its formation, and the flexibility of the optical fiber core wire is not substantially deteriorated.

Since the optical fiber core wire of the present invention has the metal layer on the surface thereof, it can be soldered more easily than the optical fiber bare wire having only the resin coating. An optical fiber tape in which multiple optical fiber cores are bundled with a soldering layer at a predetermined interval is easy to bend in any direction, and has much more flexibility than existing optical fiber tapes that have a flat cross section. Is excellent.

In the pressure sensor using the optical fiber core wire of the present invention, the radius of curvature of the elastic cylindrical body is changed by the applied pressure, and the optical fiber core wire is caused to correspond to this change to induce the macrobend. The loss of the amount of light passing through the optical fiber is measured. The amount of light passing through depends on the radius of curvature of the optical fiber core, the number of windings, and the difference in the light source.
It is safe because it is not affected by electromagnetic noise when applied as a measuring sensor in chemical equipment.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an enlarged optical fiber core wire according to the present invention.

FIG. 2 is a partial plan view showing a modified example of the present invention.

FIG. 3 is an enlarged cross-sectional view of an optical fiber core wire having a solder layer formed on its surface.

FIG. 4 is an enlarged cross-sectional view showing a conventional optical fiber tape.

FIG. 5 is a schematic cross-sectional view showing another modification of the present invention.

[Explanation of symbols]

 1 Optical fiber core wire 2 Optical fiber 3 UV curable resin layer 4 Base metal layer 5 Surface metal layer 6 Optical fiber tape 9 Solder layer 15 Pressure sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location G01L 1/04 11/00 B 9009-2F G02B 6/00 (72) Inventor Toshiaki Kurobane Neyagawa, Osaka 2-5, Kusunekita-cho, Ichi, Kyowa Electric Line Co., Ltd. (72) Inventor Shigeo Shimizu 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (5)

[Claims] 1. An optical fiber wire comprising an optical fiber composed of a core and a clad covered with an ultraviolet curable resin, a thin base metal layer is provided on the peripheral surface of the optical fiber, and then a surface metal having a thickness of 2 to 20 μm is formed by electroplating. An optical fiber core forming a layer. 2. An optical fiber wire comprising an optical fiber consisting of a core and a clad covered with an ultraviolet curable resin, a thin base metal layer is provided on the peripheral surface of the optical fiber wire, and then a surface metal having a thickness of 2 to 20 μm is formed by electroplating. After forming the layers,
Further, an optical fiber core wire on the surface of which a solder layer having a thickness of 1 to 5 μm is formed. 3. An optical fiber comprising a core and a clad is coated with an ultraviolet curable resin, and then a plurality of optical fiber core wires having a base metal layer and a surface metal layer formed on the peripheral surface thereof are used at predetermined intervals. An optical fiber tape in which a plurality of optical fiber core wires are bound together by soldering or an adhesive. 4. An optical fiber consisting of a core and a clad is covered with a plastic resin, and then a light source is provided at one end and a light receiving portion is provided at the other end of an optical fiber core wire on which a base metal layer and a surface metal layer are formed. A pressure sensor that measures the pressure applied to the optical fiber core wire by coupling by utilizing the fluctuation of the light quantity due to the change in the refractive index of the core / clad of the optical fiber core wire. 5. An optical fiber consisting of a core and a clad is covered with a plastic resin, and then an optical fiber core wire having a base metal layer and a surface metal layer formed on the peripheral surface thereof is wound around an elastic cylindrical body. A pressure sensor for measuring a pressure applied to the outer circumference of an elastic tubular body by utilizing a macrobend effect of an optical fiber core wire by connecting a light source to one end of the core wire and a light receiving portion to the other end.