JP2023003953A - Lighting device - Google Patents

Abstract

To provide a lighting device using an illumination plastic optical fiber that can efficiently acquire lateral plane light emission.SOLUTION: A lighting device includes: a core 1 made of a wire having flexibility; and an illumination plastic optical fiber 2 wound around the core 1 spirally.SELECTED DRAWING: Figure 1

Description

The present invention relates to an illumination device using an illuminated plastic optical fiber.

A plastic optical fiber used for optical transmission has a core (inner layer) and a clad (outer layer) made of a transparent resin, which are concentrically formed into perfect circles. A plastic optical fiber having such a structure efficiently transmits light incident from one end to the other end while repeating total reflection at the interface between the core and the clad. It is used for applications such as optical transmission materials for automobiles. These are used as a means of transmitting light that enters from one end to the other end without leaking in the middle. A method of using it as a transmitter has been proposed. (Patent Documents 1 and 2). If it is possible to make this light leak from a part (side surface) of the plastic optical fiber in the longitudinal direction and function as a linear light emitter, it can be used for indoor and outdoor lighting, as an alternative to neon signs and electronic displays, and for other decorative purposes. can be used for sensor applications.

As such a plastic optical fiber for side emission (illumination plastic optical fiber), for example, an illumination plastic optical fiber in which a light reflecting layer is formed at the interface between a core and a clad has been proposed (see, for example, Patent Document 3).

JP 2014-144319 A JP 2007-175049 A JP-A-2000-39518

However, with the method of providing a light reflecting layer as described in Patent Document 3, uniform light emission cannot be obtained from the entire fiber. In order to obtain brighter and more uniform side emission with an illuminated plastic optical fiber, it is important to have a uniform curvature throughout the fiber.

Accordingly, the present invention provides an illumination device using an illumination plastic optical fiber capable of efficiently obtaining side emission.

In order to solve the above problems, the present invention has the following configurations. Namely
The lighting device is characterized by having a flexible wire material as a core material, and an illuminating plastic optical fiber spirally wound around the core material.

According to the present invention, a lighting device with efficient side emission can be obtained.

1 is a schematic diagram of a portable lighting device according to an embodiment of the present invention; FIG.

First, the heartwood will be explained. A wire rod used as a core material needs to have flexibility in order to improve the handleability of the lighting device. Having flexibility here means that it can be easily bent and twisted in any direction and exhibits characteristics that do not cause yield or breakage, and has a bending elastic modulus of 10 to 4000 MPa. Say things. Examples of flexible core materials include polyurethane fibers, polyolefin fibers, natural rubber fibers, polyamide fibers, polyester fibers, etc. Plastic optical fibers having a core and a clad may be used as the core material. preferable. By using a plastic optical fiber as the core material, it becomes possible to transmit light inside the core material, and it can be used as a side emission type light guide path.

When the core material is a plastic optical fiber, it has a three-layer structure consisting of a core, a first clad, and a second clad. , 10 to 30% by weight of hexafluoropropylene, 45 to 75% by weight of tetrafluoroethylene, 10 to 35% by weight of vinylidene fluoride, and 1 to 10% by weight of perfluoroalkyl vinyl ethers. . Further, it is more preferable that the fluorine composition weight percentage is 70 to 74%. By setting the composition in this range, the numerical aperture (NA) of the plastic optical fiber can be easily set to 0.60 to 0.65, and the critical angle at the core/cladding interface is large, so the light amount loss due to bending is can be made smaller. In addition, the adhesiveness to the core material represented by PMMA is good, and well-balanced plastic optical fiber properties are obtained in which mechanical properties such as bending resistance, low adhesiveness, and heat resistance are compatible.

Further, the second clad contains 10 to 35% by weight of ethylene, 45 to 69% by weight of tetrafluoroethylene, and 5 to 15% by weight of hexafluoropropylene when the total amount of monomer components for obtaining the resin constituting the second clad is 100% by weight. It is preferably a copolymer obtained from 0.01 to 10% by weight of a fluorovinyl compound represented by the following general formula (1).
_CH2 = _{CX1(CF2)nX2 (} ^{1 )}
(In the formula, X ¹ represents a fluorine atom or a hydrogen atom, X ² represents a fluorine atom, a hydrogen atom or a carbon atom, and n is an integer of 1 to 10.)
More preferably, it contains a copolymer containing 0.01 to 10% by weight of a fluorovinyl compound represented by CH ₂ =CF(CF ₂ ) ₃ H as a copolymerization component. The second cladding is preferably substantially composed of such a copolymer.

If the ethylene content of the second clad is less than 10% by weight, the molding stability may deteriorate. If it exceeds 35% by weight, the crystallinity may increase, the transparency may decrease, and the transmission characteristics may deteriorate. The proportion of ethylene is preferably 11 to 30% by weight. If the tetrafluoroethylene content is less than 45% by weight, molding stability may deteriorate. If it exceeds 69% by weight, crystallinity may increase, transparency may decrease, and transmission characteristics may deteriorate. In addition, the melting point increases, and the fluidity near the spinning temperature of the optical fiber may decrease. If the hexafluoropropylene content is less than 5% by weight, the flexibility may decrease and the bending loss may decrease. If it exceeds 15% by weight, the workability may deteriorate due to increased stickiness.

In particular, in order to impart excellent adhesion and heat resistance to the core (co)polymer mainly composed of methyl methacrylate, the amount of the fluorovinyl compound represented by the above formula (1) is 0.01 to 0.01. It is desirable to contain 10% by weight. On the other hand, the content is desirably 10% by weight or less in view of the content of other copolymer components.

Next, the illuminated plastic optical fiber will be described. Illuminated plastic optical fibers (hereinafter sometimes abbreviated as optical fibers) have a two-layer structure consisting of a core (inner layer) and a clad (outer layer) made of transparent resin, and have a circular cross section in the radial direction. be.

Examples of the transparent resin used for the core include polymethyl methacrylate (PMMA), a copolymer containing methyl methacrylate as a main component, polystyrene, polycarbonate, polyorganosiloxane (silicone), norbornene, and the like. Methacrylate is a preferred resin for illumination plastic optical fibers in terms of transparency, refractive index, bending properties, and heat resistance.

The transparent resin used for the clad is a polymer obtained by polymerizing a polymerization component containing 90% to 100% by mass of vinylidene fluoride, and has a crystallinity of 45% to 52%. preferable. When the vinylidene fluoride content is 90% by mass or more, the copolymer tends to have crystallinity, and the vinylidene fluoride content is preferably 100% by mass. When vinylidene fluoride is 100% by mass, it becomes easier to obtain the degree of crystallinity described later. Polymerization components containing 90% by mass to 100% by mass of vinylidene fluoride include vinylidene fluoride alone, vinylidene fluoride/tetrafluoroethylene, vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene, vinylidene fluoride/hexafluoroacetone, and the like. Polymerization components from which copolymers containing vinylidene fluoride are synthesized. In the case of a copolymer, the proportion of the vinylidene fluoride component in the copolymer in terms of mass is 90% by mass to 100% by mass. When a polymer obtained by polymerizing a polymer component containing 90% by mass to 100% by mass of vinylidene fluoride is used as the clad, since vinylidene fluoride is a highly crystalline resin, the interface between the core and the clad of the optical fiber Also, it is considered that light scattering is likely to occur at the interface between the amorphous region and the crystalline region in the clad, and as a result, light emission from the side surface of the fiber increases, which is preferable. In addition, when the crystallinity of vinylidene fluoride used in the present invention is 45% or more, the light diffusion effect increases, and the light emission effect from the side surface of the fiber increases, which is preferable, and 46% or more is more preferable. In addition, if the crystallinity of vinylidene fluoride is 52% or less, light emission from the side surface can be effectively obtained, and the length of the optical fiber in the longitudinal direction at which light emission from the side surface can be obtained can be extended. It is preferable because it is possible, and 50% or less is more preferable.

Also, the thickness of the clad layer is preferably 2.0 μm to 15.0 μm. When the thickness is 2.0 μm or more, total reflection can occur at the interface between the core and the clad, and the thickness is more preferably 2.5 μm or more. In addition, when the thickness is 15.0 μm or less, the absorption in the clad is suppressed, and the length in the longitudinal direction with side emission is improved. More preferably, it is 10.0 μm or less. More preferably, it is 7.5 μm or less.

The melt flow rate (hereinafter sometimes abbreviated as MFR) of the clad used for the illumination plastic optical fiber is 5 to 100 g/10 minutes (conditions: temperature 230° C., load 3.8 kg, orifice diameter 2 mm, length 8 mm). A more preferred MFR range is 10 to 100 g/10 min. By setting the MFR within the above range, extrusion becomes easy and spinning proceeds smoothly. In addition, the adhesion to the core layer can be properly maintained, the eccentricity can be improved, and the fluctuation of the outer diameter of the illumination plastic optical fiber can be suppressed.

The diameter of the illuminating plastic optical fiber is preferably 400 μm or less. When it is 400 μm or less, it is highly flexible, easy to handle, and can emit light with a complicated shape. Further, when the thickness is 400 μm or less, the circumferential length becomes small, so the leakage from the side surface is reduced, the light transmission loss is improved, and conversely, the length in the longitudinal direction with side emission is improved. More preferably, it is 300 µm or less. On the other hand, although the lower limit of the diameter of the illumination plastic optical fiber is not particularly limited, it is preferably 100 μm or more from the viewpoint of production efficiency.
Also, the diameter of the wound illuminating plastic optical fiber is preferably smaller than the fiber diameter of the core material. By making the diameter smaller than the core material, it can be easily wound around the core material.

FIG. 1 shows a schematic diagram of a lighting device according to an embodiment of the present invention. The illumination device comprises a core material 1 and an illuminating plastic optical fiber 2 . It is preferable that the lead angle θ between the illuminating plastic optical fiber and the core member in the vertical direction when spirally wound is 10 degrees or more and 50 degrees or less. When the angle is 10 degrees or more, the flexibility of the core material is not impaired even after winding, and when the angle is 50 degrees or less, a sufficient amount of side emission can be ensured. It is more preferably 15 degrees or more, and still more preferably 20 degrees or more. As a method of spirally winding, any method such as manual winding or a string making machine can be used.

INDUSTRIAL APPLICABILITY The lighting device according to the present invention can be suitably used for applications such as medical endoscope lighting, ophthalmic surgery lighting, catheter lighting, microscope lighting, wall decoration lighting, and room lighting. In particular, it is suitable for endoscope applications, ophthalmic surgery applications, and catheter applications, which require a wide irradiation range and are often handled in the dark.

EXAMPLES The present invention will be described in more detail below with reference to examples. The core materials and clad materials used in each example and comparative example and the optical fibers produced in each example and comparative example were evaluated by the following methods.

Composition ratio of clad material: Determined using solid ¹⁹ F NMR (AVANCE NEO 400 manufactured by Bruker) and FT-IR (FT-IR manufactured by Bio-Rad Digilab).

Fiber diameter: five randomly selected optical fibers were cut perpendicularly to the drawing direction, and the cross section was polished so that the interface between the core and the clad could be observed. Magnified observation was performed using a scope VHX-7000 (manufactured by Keyence). Magnification of the magnified observation was selected from a range of 10 to 200 times, and a range in which the entire cross section was within the field of view and the interface could be observed. The diameter of the optical fiber was measured in cross section. The diameter was measured for each of the 5 cross sections, and the average value was calculated.

Flexural modulus: Measured according to ASTM D790 (2010). The size of the test piece was 127 mm x 13 mm x 3.1 mm. The measurement unit of ASTM D790 is kg/cm ² , and the flexural modulus was obtained from the slope of the stress-bending displacement curve at the point where the slope becomes the largest at the initial stage of stress application, ie, the tangent line at that point. The flexural modulus of the core material was evaluated as the flexural modulus of the core fiber.

Side emission: Regarding the side emission of the illumination plastic optical fiber, the brightness in the unwound state was set to 3, and relative comparison was made on a scale of 1 to 5 (1: dark, 5: bright).

The abbreviations of the monomers used as raw materials for the copolymers used in the examples are as follows.
2F: Vinylidene fluoride 4F: Tetrafluoroethylene 6F: Hexafluoropropylene
FVE: heptafluorovinyl ether.

[Example 1]
As a clad material, a VDF homopolymer (refractive index: 1.420, MFR: 22 g/10 min) having the composition shown in Table 1 was supplied to the composite spinning machine. Furthermore, PMMA (refractive index 1.492) produced by continuous concentric polymerization is supplied as a core material to a composite spinning machine, and the core and clad are core-sheath composite melt-spun to obtain a fiber diameter of 250 μm (core diameter: 240 μm, clad thickness: 5.0 μm) illuminated plastic optical fiber was obtained. In addition, the core material is a vinylidene fluoride (2F)/tetrafluoroethylene (4F)/hexafluoropropylene (6F)/heptafluoropropyl vinyl ether copolymer having a copolymerization ratio shown in Table 1 as a first clad material (refractive index 1.360, fluorine content 71.7%) was used as the second clad material, and the copolymerization ratio of ethylene/tetrafluoroethylene (4F)/hexafluoropropylene (6F)/fluorovinyl compound in Table 1 was used. The combined (containing carbonate group) (refractive index 1.385) is supplied to the composite spinning machine, and PMMA (refractive index 1.492) produced by continuous concentric polymerization is supplied to the composite spinning machine as a core material, A bare fiber having a fiber diameter of 1000 μm (a core diameter of 980 μm, a first clad thickness of 5.0 μm and a second clad thickness of 5.0 μm) obtained by core-sheath composite melt spinning of the core and the clad at 240° C. was used. The illuminating plastic optical fiber is wound around a 1 m long core material at a uniform pitch so that the lead angle is 30 degrees and the pitch is 2 mm. Obtained. The lighting device obtained by connecting the white LED to the lighting device had a larger side emission than the single lighting plastic optical fiber, and it was possible to irradiate the light from the tip of the optical fiber of the core material.

[Example 2]
A lighting device was obtained in the same manner as in Example 1, except that only polymethyl methacrylate fibers with a diameter of 1000 μm were used for the core material. As in Example 1, the side emission of the illuminated plastic optical fiber increased.

[Example 3]
A lighting device was obtained in the same manner as in Example 1 except that the fiber diameter of the core material was 200 μm (core diameter 180 μm, clad thickness 5.0 μm). Sufficient side emission was obtained, but the winding process was difficult.

[Example 4]
A lighting device was obtained in the same manner as in Example 1, except that the winding lead angle was changed to 10 degrees. Sufficient lateral light emission was obtained, but the flexibility of the core material was impaired, and the winding process was difficult.

[Example 5]
A lighting device was obtained in the same manner as in Example 1, except that the winding lead angle was changed to 70 degrees. Side emission was weaker than in Example 1.

[Comparative Example 1]
An illuminated plastic optical fiber was obtained in the same manner as in Example 1. No core material was used, and a white LED was connected to the end to irradiate light.

1: core material 2: illuminated plastic optical fiber θ: lead angle

Claims (10)

What is claimed is: 1. A lighting device comprising a flexible wire as a core material, and an illumination plastic optical fiber spirally wound around the core material. 2. The illumination device of claim 1, comprising plastic optical fibers in the core. 3. The lighting device according to claim 1, wherein the diameter of the illuminating plastic optical fiber is smaller than the diameter of the core. 4. The illuminating device according to claim 1, wherein a lead angle θ between the illuminating plastic optical fiber and the core member in the vertical direction is 10 degrees or more and 50 degrees or less. The core material plastic optical fiber is a plastic optical fiber having a three-layer structure of a core, a first clad, and a second clad, and the second clad is ethylene of 10 to 35% by weight.
Tetrafluoroethylene 45-69% by weight
Hexafluoropropylene 20 to 45% by weight and the following formula (1)
_CH2 =CX1(CF2) _nX2 ^{( 1} )
(In the formula, X ¹ represents a fluorine atom or a hydrogen atom, X ² represents a fluorine atom, a hydrogen atom or a carbon atom, and n is an integer of 1 to 10.)
5. The lighting device according to any one of claims 2 to 4, comprising a copolymer containing 0.01 to 10% by weight of a fluorovinyl compound represented by: as a copolymer component. 10 to 30% by weight of hexafluoropropylene in the first clad of the core plastic optical fiber;
45 to 75% by weight of tetrafluoroethylene,
10-35% by weight of vinylidene fluoride and 1-10% by weight of perfluoroalkyl vinyl ethers
6. The lighting device according to any one of claims 2 to 5, characterized in that it is made of a copolymer containing as a copolymer component. 7. The illumination device according to claim 1, wherein the cladding of said illumination plastic optical fiber is made of a polymer containing 90% by weight or more of vinylidene fluoride. An in-vivo illumination device comprising the illumination device according to any one of claims 1 to 7. An illumination probe for ophthalmic surgery, comprising the illumination device according to any one of claims 1 to 7 as illumination for ophthalmic surgery. A blood vessel catheter having the illumination device according to any one of claims 1 to 7 as a catheter illumination or an optical sensor.

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