Light-emitting device

Abstract

To provide a light-emitting device with a smaller burden on consideration for environmental resistance.SOLUTION: A light-emitting device 10 includes a light source 11, an optical fiber 12 that transmits light from the light source 11, and light extracting means 132 of changing a direction where the optical fiber 12 extends and generating stress in the optical fiber 12 to make a side surface emit light. The optical fiber 12 includes a core to which the light from the light source 11 is incident, and a clad provided to cover the core. To the clad of the optical fiber 12, a scattering body is added.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to light emitting devices. [Background technology]

[0002] Light emitting devices that use light emitting elements such as LEDs are widely known (for example, Patent Document 1, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-225140 A Summary of the Invention [Problem to be solved by the invention]

[0004] In light-emitting devices using light-emitting elements such as LEDs, electrical wiring is provided from a power source to the light-emitting elements. For electrical wiring of such light-emitting devices, consideration must be given to environmental resistance, such as insulation measures to prevent electric leakage, especially when the devices are used outdoors or underwater.

[0005] An object of the present invention is to provide a light-emitting device that requires less consideration for environmental resistance. [Means for solving the problem]

[0006] The present invention relates to a light source, an optical fiber for transmitting light from the light source, and a The direction of the light is changed and stress is generated in the optical fiber to emit light from the side. The optical fiber includes a core into which light from the light source is incident, and a means for connecting the core to the optical fiber. and a cladding provided to cover the optical fiber, the cladding of the optical fiber including a scattering The body is a light-emitting device to which the light is added. Effect of the Invention

[0007] According to the present invention, light from a light source is transmitted through an optical fiber with excellent environmental resistance, and the light is emitted from the side of the optical fiber by a light extraction means, thereby reducing the burden of considering environmental resistance, which is required in the case of electrical wiring. [Brief description of the drawings]

[0008] [Figure 1A] 1 is a perspective view of a light-emitting device according to an embodiment. [Figure 1B] FIG. 2 is a plan view of a light-emitting device according to an embodiment. [Diagram 2] FIG. 1 is a perspective view of an optical fiber. [Diagram 3] FIG. 4 is a side view of the light extractor. [Figure 4] FIG. 2 is a perspective view of a first modified example of the light-emitting device according to the embodiment. [Diagram 5] FIG. 11 is a perspective view of a second modified example of the light-emitting device according to the embodiment. [Figure 6] FIG. 11 is a perspective view of a third modified example of the light emitting device according to the embodiment. [Figure 7A] FIG. 11 is a perspective view of a fourth modified example of the light emitting device according to the embodiment. [Figure 7B] FIG. 13 is a perspective view of a fifth modified example of the light emitting device according to the embodiment. [Figure 8A] FIG. 13 is a perspective view of a sixth modified example of the light emitting device according to the embodiment. [Figure 8B] FIG. 13 is a perspective view of a seventh modified example of the light emitting device according to the embodiment. [Figure 9] FIG. 1 is a diagram showing the configuration of an experimental apparatus according to an embodiment of the present invention. [Figure 10A] 13 is a graph showing the relationship between the emission angle and emission intensity of fiber A in measurement 1. [Figure 10B] 13 is a graph showing the relationship between the emission angle and emission intensity of Fiber B in Measurement 1. [Figure 11] FIG. 13 is an explanatory diagram showing a measurement method for measurement 2. [Figure 12A]13 is a graph showing the relationship between the emission angle and emission intensity of fiber A in measurement 2. [Figure 12B] 13 is a graph showing the relationship between the emission angle and emission intensity of Fiber B in Measurement 2. [Figure 13A] FIG. 1 is a perspective view for explaining a method for designing a light-emitting device. [Figure 13B] FIG. 1 is a plan view for explaining a method for designing a light-emitting device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0010] 1A and 1B show a light-emitting device 10 according to an embodiment. The light-emitting device 10 according to the embodiment includes a laser light source 11, an optical fiber 12, and a light extracting member 13. In the light-emitting device 10, laser light from the laser light source 11 is transmitted through the optical fiber 12, and the light extracting member 13 extracts the laser light from the optical fiber 12 and emits it from the side.

[0011] Examples of the laser light source 11 include a semiconductor laser, a solid-state laser, a gas laser, etc. From the viewpoint of device miniaturization and energy saving, the laser light source 11 is preferably a semiconductor laser.

[0012] The laser light source 11 may be composed of a plurality of lasers. For example, the laser light source 11 may be composed of a combination of semiconductor lasers of each color of RGB. In that case, it is possible to instantaneously realize various colored lights. In addition, in the laser light source 11 composed of a plurality of lasers, it is easy to adjust the emission intensity and the optical coherence.

[0013] The laser light source 11 may emit visible light, or may emit infrared light or ultraviolet light. When the laser light source 11 emits infrared light or ultraviolet light, the light-emitting device 10 can be used in chemical reaction processes and various sensing applications.

[0014] The laser light source 11 can obtain high visibility of the light emitted from the light emitting device 10 by utilizing the speckle effect caused by optical interference. In the laser light source 11, the speckle effect can be changed by adjusting the oscillation spectrum (longitudinal mode) width of the laser light, that is, the visibility of the observer can be changed. The narrower the oscillation spectrum width, the stronger the speckle effect, and conversely, the wider the oscillation spectrum width, the weaker the speckle effect. In the case of a semiconductor laser, the oscillation spectrum width can be adjusted by superimposing a high-frequency signal on the drive current. In addition, the speckle effect can be changed by adjusting the reflection and scattering position by changing the incident position and incident angle of the laser light from the laser light source 11 into the optical fiber 12.

[0015] In the case of a light-emitting device using a light-emitting element such as an LED, the conversion efficiency from electrical energy to light energy is not 100%, so electrical energy that is not converted into light energy is converted into thermal energy and causes heat generation. In addition, since spontaneous emission light is used, in order to improve visibility, it is necessary to supply a lot of electrical energy to increase the amount of light, which promotes heat generation. Therefore, a cooling mechanism such as a cooling fan or a heat sink is required, which makes it difficult to make the device small and thin. However, the laser light source 11 used in the light-emitting device 10 according to the embodiment can obtain high visibility by utilizing the speckle effect caused by optical interference as described above without generating such heat. As a result, since a cooling mechanism is not required, the light-emitting device 10 can be made small and thin.

[0016] As shown in FIG. 2, the optical fiber 12 has a core 121, a cladding 122, and a coating layer 123.

[0017] The core 121 is provided at the center of the cross section. The core 121 has a relatively high refractive index, and examples of the material for forming the core 121 include glass materials such as quartz, and organic materials such as acrylic resins and fluorine-based resins. The diameter of the core 121 is, for example, 10 μm or more and 2000 μm or less.

[0018] The cladding 122 is provided so as to cover the core 121. The cladding 122 has a relatively low refractive index, and examples of the material for forming the cladding 122 include organic materials such as silicone resin, acrylic resin, and fluororesin, and glass materials such as quartz. The outer diameter of the cladding 122 is, for example, 100 μm or more and 10,000 μm (10 mm) or less.

[0019] Covering layer 123 is provided so as to cover clad 122. Examples of materials for forming covering layer 123 include organic materials such as acrylic resin, nylon resin, and fluororesin. The outer diameter of covering layer 123 is, for example, 200 μm or more and 20000 μm (20 mm) or less.

[0020] From the viewpoints of durability against laser light, environmental resistance in outdoor use, and manufacturability, it is preferable that the optical fiber 12 has a core 121 made of quartz, a clad 122 made of silicone resin, and a coating layer 123 made of fluororesin.

[0021] From the viewpoint of facilitating extraction of the laser light, the optical fiber 12 is preferably a light scattering fiber to which a scatterer is added. The scatterer is usually added to the core 121 and / or the clad 122, but from the viewpoint of producing a speckle effect without reducing the optical coherence of the laser light source 11, it is preferable that the scatterer is added at least to the clad 122, and more preferable that the scatterer is not added to the core 121 and is added to the clad 122. If the scatterer is added to the core 121, the number of scatterings of the laser light propagating through the core 121 increases, so that the optical coherence of the laser light source 11 itself is likely to decrease, whereas if the scatterer is added to the clad 122, the laser light is scattered only when it reaches the interface between the core 121 and the clad 122, so that the number of scatterings is small, and therefore the decrease in optical coherence is small. The scatterer may also be added to the coating layer 123. The coating layer 123 may have a light scattering function due to the crystals of the forming material.

[0022] Examples of the scatterer include inorganic materials such as quartz, organic materials such as polymethyl methacrylate resin (PMMA), ceramic materials, powders of metal materials, etc. The scatterer preferably contains one or more of these. The concentration of the scatterer added may be appropriately adjusted according to the laser light extraction conditions. If the concentration of the scatterer added is high, many mode mismatching parts are formed at the interface between the core 121 and the cladding 122, making it easier to extract the laser light when stress is generated.

[0023] The light extracting member 13 includes a base material 131 , a light extracting portion 132 , and a light reflecting portion 133 .

[0024] The base material 131 is formed in a plate shape. Examples of materials for forming the base material 131 include resin, metal, glass, and wood. The base material 131 may be formed of a transparent material that does not absorb laser light. The base material 131 may be formed of a material that has a high reflectance of laser light. When the base material 131 is formed of a light-transmitting material, a scattering material or a fluorescent material may be added to the base material 131 in order to increase the emission intensity of the laser light.

[0025] The light extraction sections 132 are formed of cylindrical bodies, and a plurality of them are erected on the base material 131. The plurality of light extraction sections 132 are arranged at vertices of a zigzag shape in a front view of the surface of the base material 131, and are arranged such that the portions of the odd-numbered light extraction sections 132 and the even-numbered light extraction sections 132 that are close to each other overlap with each other in a front view in the direction in which the zigzag shape extends, as shown in Fig. 3. The plurality of light extraction sections 132 may be arranged at equal intervals in the direction in which the zigzag shape extends, or may not be arranged at equal intervals.

[0026] Examples of materials for forming the light extraction section 132 include resin, metal, glass, and wood. The light extraction section 132 may be formed of a transparent material that does not absorb laser light. The light extraction section 132 may also be formed of a material that has a high reflectance of laser light. When the light extraction section 132 is formed of a light-transmitting material, a scattering material or a phosphor may be added to the light extraction section 132 in order to increase the emission intensity of the laser light.

[0027] The light reflecting portion 133 is composed of a slender columnar body having a cross section of a right-angled isosceles triangle, and a pair of light reflecting portions 133 are provided on the substrate 131. The pair of light reflecting portions 133 are provided along the multiple light extraction portions 132 arranged on the substrate 131, sandwiching the multiple light extraction portions 132 from both sides, and each of the light reflecting portions 133 is provided so that the inclined surfaces corresponding to the hypotenuse of the cross section of the right-angled isosceles triangle face the light extraction portion 132 side. The shape of the inclined surface of the light reflecting portion 133 facing the light extraction portion 132 side is not limited to a uniform plane, and can be any shape such as a concave curved surface, a convex curved surface, or a surface combining a flat surface and a curved surface, and can be designed to reflect the side light emitted from the light extraction portion 132 in a desired direction.

[0028] Examples of materials for forming the main body of the light reflecting portion 133 include resin, metal, glass, wood, etc. The inclined surface of the light reflecting portion 133 is a light reflecting surface, and is preferably formed of a light reflecting material such as a metal that does not absorb laser light.

[0029] The light extracting member 13 may be formed integrally with the main body of the base material 131, the light extracting portion 132, and the light reflecting portion 133 using the same material. In this case, the light extracting member 13 can be produced by resin molding or machining, but a light extracting member 13 having a complex structure can be easily produced using a 3D printer.

[0030] In the light-emitting device 10 according to the embodiment, one end of an optical fiber 12 is connected to a laser light source 11. The optical fiber 12 extends from the laser light source 11 to a light extracting member 13, and is provided on a base material 131 of the light extracting member 13 so as to thread between a plurality of light extracting portions 132 arranged at vertices of a zigzag shape.

[0031] Specifically, at the first light extraction section 132, the optical fiber 12 is wound around the portion on the side where the adjacent second light extraction section 132 is located, and then extends toward the second next light extraction section 132, and at the second light extraction section 132, the optical fiber 12 is wound around the portion on the side where the adjacent third light extraction section 132 is located, and then extends toward the third next light extraction section 132, and thereafter, at the odd-numbered light extraction section 132, the optical fiber 12 is wound around the portion on the side where the adjacent even-numbered light extraction section 132 is located, and then extends toward the next even-numbered light extraction section 132, and at the even-numbered light extraction section 132, the optical fiber 12 is wound around the portion on the side where the adjacent odd-numbered light extraction section 132 is located, and then extends toward the next odd-numbered light extraction section 132, and as a result, the extending direction changes depending on the light extraction section 132, and is bent so as to form a waveform when viewed from the front on the surface of the substrate 131. The bending of this waveform has, for example, an amplitude of 0.7 mm to 10 mm and a period of 2 mm to 50 mm. These amplitudes and periods can be determined depending on the structure and shape of the optical fiber 12 and the amount of leaked light. These amplitudes and periods do not have to be constant. In addition, in the portion of the optical fiber 12 wound around the light extraction portion 132, stress is generated against the pressure from the light extraction portion 132 and the bending caused by the winding around the light extraction portion 132. Specifically, in the optical fiber 12, an outward stress is generated in the cross-sectional direction to resist the pressure from the light extraction portion 132, and a tensile stress is generated in the length direction on the outer circumferential side of the bend and a compressive stress is generated in the length direction on the inner circumferential side of the bend to resist the bending caused by the winding around the light extraction portion 132.

[0032] Next, the operation of the light emitting device 10 according to the embodiment will be described.

[0033] In the light-emitting device 10 according to the embodiment, the laser light source 11 emits a laser light. The laser light from the laser light source 11 is incident on the core 121 of the optical fiber 12. The optical fiber 12 transmits the laser light from the laser light source 11. In the portion of the optical fiber 12 wound around the light extraction portion 132 on the light extraction member 13, the occurrence of stress induces leakage of the laser light from the core 121, resulting in side emission. Therefore, the light extraction portion 132 of the light extraction member 13 constitutes the light extraction means. The side emission of the laser light is mainly emitted in the pressing direction by the light extraction portion 132 and in a direction inclined toward the transmission direction of the laser light of the optical fiber 12 from the vicinity of the apex of the bent portion wound around the light extraction portion 132. Note that the side emission is also emitted in other directions, although not often. The side emission of the laser light from the optical fiber 12 is reflected by the inclined surface of the light reflecting portion 133, the light path is changed, and the light proceeds in the normal direction of the surface of the base material 131. Therefore, the light reflecting portion 133 constitutes the light reflection means. As a result, in the light-emitting device 10 according to the embodiment, a line-shaped laser beam is emitted along the length of the optical fiber 12.

[0034] The emission of laser light from the light-emitting device 10 according to the embodiment gives rise to a speckle phenomenon in which a speckle distortion pattern is generated on the retinal cells of the observer due to optical interference, thereby providing high visibility.

[0035] When an image of light with good optical coherence (coherence), such as laser light, is projected onto a screen and observed with the naked eye, the image on the screen is perceived as being superimposed with speckle distortion due to the speckle effect of light. This speckle distortion does not exist on an actual screen, but light with slightly different phases reflected from different points on the screen interferes on the human retinal cells, forming a distorted light intensity pattern in space. Therefore, when the human observation position or the position of the screen changes slightly, the new light with a different phase interferes on the retinal cells due to the displacement of the observation position, generating a different distorted light intensity pattern, and the observer is sensitive to the change. Since this distortion is due to optical interference of light, the change is large even with weak light, and has a greater impact on the observer than the difference in appearance due to the luminous intensity of spontaneous emission light. Typically, in laser projection devices and the like, in order to reduce this speckle effect, the spectral width of the light source is broadened to reduce optical coherence, or the screen is mechanically vibrated and moved at a speed that cannot be detected by humans, thereby averaging out the speckle distortion formed on the retina and reducing the discomfort felt by the observer.

[0036] In contrast, the light emitting device 10 according to the embodiment deliberately utilizes speckle distortion, which is easily visible to humans. Specifically, laser light with good optical coherence is transmitted from a laser light source 11 through an optical fiber 12. In a light extraction member 13, stress is generated in the optical fiber 12 by pressing and bending, which induces leakage of the laser light from the core 121, causing side emission. At this time, in order to utilize the speckle distortion, it is preferable to reduce the number of reflections and scatterings of the laser light as much as possible and extract it directly from the optical fiber 12 without reducing the optical coherence of the laser light source 11.

[0037] In the light-emitting device 10 according to the embodiment, when the optical fiber 12 is a light-scattering fiber to which a scatterer is added, in the linearly extending portion where the influence of stress in the optical fiber 12 is small, side light emission due to light scattering inherent to the light-diffusing fiber is emitted in almost all directions. That is, in this case, the side light emission includes a mixture of light emitted in a direction caused by the stress caused by the pressing by the light extraction part 132 and bending caused by winding around the light extraction part 132, and scattered light inherent to the light-diffusing fiber. In addition, since side light emission can be obtained from other than the vicinity of the apex of the bent part wound around the light extraction part 132 in the optical fiber 12, it is possible to obtain substantially uniform side light emission over the entire length of the optical fiber 12 provided on the light extraction member 13. Furthermore, in a light-emitting device using a conventional light-emitting element such as an LED, which is a point light source or a surface light source with a limited area, which causes interruptions in the light emission, in the light-emitting device 10, when the optical fiber 12 is a light-diffusing fiber, it is possible to obtain continuous light emission without interruptions.

[0038] On the other hand, when the optical fiber 12 is a general fiber to which no scatterers are added, in the linearly extending portion of the optical fiber 12 where the effect of stress is small, the amount of side emission decreases as it moves away from the apex of the bent portion wound around the light extraction portion 132. In addition, since the number of times the laser light is scattered is small, it is possible to prevent deterioration of the optical coherence and obtain high visibility. However, compared to when the optical fiber 12 is a light scattering fiber, it is necessary to generate a larger stress in order to obtain the same amount of side emission. In addition, in order to obtain uniform side emission over the entire length of the optical fiber 12, it is necessary to increase the number of light extraction portions 132.

[0039] The optical fiber 12 may be configured such that a general fiber in a portion from the laser light source 11 to the light extracting member 13 is connected to a light scattering fiber in a portion provided on the light extracting member 13. In this case, the side light emission of the optical fiber 12 is obtained mostly on the light extracting member 13. The optical fiber 12 may also be configured such that the entire optical fiber 12 is a light scattering fiber. In this case, the side light emission of the optical fiber 12 is obtained not only on the light extracting member 13. Furthermore, the optical fiber 12 may be configured such that a light diffusing fiber in a portion where light is desired to be emitted is connected to a general optical fiber 12 in a portion where light is not desired to be emitted.

[0040] When the multiple light extraction sections 132 each generate an equal stress in the optical fiber 12, the emission intensity of the side light emission from the optical fiber 12 is stronger on the side close to the laser light source 11 than on the side away from the laser light source 11 in the length direction of the optical fiber 12. In order to make the emission intensity of the side light emission uniform in the length direction of the optical fiber 12, the stress generated in the optical fiber 12 in the light extraction section 132 on the side away from the laser light source 11 may be made larger than the stress generated in the optical fiber 12 in the light extraction section 132 on the side close to the laser light source 11. Specifically, for example, the overlapping range of the portions of the light extraction sections 132 on the sides close to each other shown in the front view of FIG. 3 may be gradually increased from the side close to the laser light source 11 toward the side away from the laser light source 11.

[0041] According to the light-emitting device 10 of the above embodiment, the laser light from the laser light source 11 is transmitted through the optical fiber 12, which is considered to have excellent environmental resistance, and the laser light is emitted from the side of the optical fiber 12 by the light extraction part 132 of the light extraction member 13, so that the burden of consideration for environmental resistance required in the case of electrical wiring can be reduced. Therefore, it can be used underwater, and is effective for applications such as underwater displays in pools and bathtubs, and for supplying light energy in underwater fishing and algae cultivation. In addition, unlike electrical wiring, the optical fiber 12 can transmit high light energy even with a small diameter, so it is effective for applications where wiring space is limited, such as in-vehicle applications.

[0042] The light-emitting device 10 according to the embodiment transmits laser light using the low-loss optical fiber 12, so that the distance from the laser light source 11 to the light extracting member 13 can be increased. Therefore, the light-emitting device 10 is effective for applications such as plant plants where the influence of heat generated by the light source is a problem.

[0043] In a conventional light-emitting device using light-emitting elements such as LEDs, the emission color (wavelength) is determined by the initial structure, so that changing the emission color later requires replacing all the light-emitting elements. However, in the light-emitting device 10 according to the embodiment, the emission color can be changed by simply changing the laser light source 11.

[0044] In the light-emitting device 10 according to the embodiment, the light emission intensity of the side light emission changes depending on the magnitude of the stress generated in the optical fiber 12, so that the light extraction section 132 changes due to an external factor, and the stress generated in the optical fiber 12 also changes accordingly, so that the light-emitting device 10 can be used as a sensor.

[0045] Specifically, the light extraction unit 132 may be configured to change its position, etc., by the action of an external force, for example, a person, a machine, a plant, etc. pushing and pulling it. Specifically, if the position of the light extraction unit 132 is changed by stepping on it, stepping on it increases the luminous intensity of the side light emission of the optical fiber 12, and increases the luminous intensity of the scattered light in the part of the optical fiber 12 ahead of the light extraction member 13, thereby forming a display device for destination guidance. In addition, the light extraction unit 132 may be formed of a shape memory alloy or a shape memory resin, and may change its shape, etc., depending on changes in the ambient temperature and moisture absorption. Furthermore, the light extraction unit 132 may be configured to change its position, shape, etc. over time and function as a time limit timer.

[0046] As shown in FIG. 4, the light-emitting device 10 according to the embodiment may further include an embedding member 14 of a light-transmitting material laminated on a base material 131 of the light-extracting member 13 so that the optical fiber 12, the light-extracting portion 132, and the light-reflecting portion 133 are embedded. The embedding member 14 can improve the light-extraction efficiency. Examples of materials for forming the embedding member 14 include organic materials such as silicone resin, acrylic resin, and urethane resin. The embedding member 14 may contain a scatterer or a phosphor. The degree of the speckle effect can be adjusted by adding the scatterer or phosphor. For example, to increase the degree of the speckle effect, the amount of these added may be reduced. Conversely, to decrease the degree of the speckle effect, the amount of these added may be increased. The same effect can also be achieved by a cover that covers the light-extracting portion 132 and the light-reflecting portion 133 on the base material 131 and the optical fiber 12 without embedding them.

[0047] In the above embodiment, the light extracting member 13 has the light reflecting portion 133, but the present invention is not particularly limited thereto, and as shown in Fig. 5, the light extracting member 13 may not have the light reflecting portion 133 and may be composed of only the base material 131 and the light extracting portion 132. In this case, the number of reflections of the side light emission of the optical fiber 12 is reduced, so that the optical coherence is maintained, and thereby the decrease in visibility can be suppressed.

[0048] In the above embodiment, a pair of light reflecting portions 133 are arranged along the plurality of light extraction portions 132 arranged on the base material 131 and sandwich the plurality of light extraction portions 132 from both sides, but the present invention is not particularly limited to this, and a short light reflecting portion 133 may be arranged on the opposite side across the optical fiber 12 in the direction in which the optical fiber 12 emits side light when pressed, in correspondence with each light extraction portion 132, as shown in Fig. 6. In addition, in a configuration in which optical fibers are arranged two-dimensionally to emit light in a planar manner, the emission intensity within the light emitting surface can be made uniform by providing a plurality of light reflecting portions in a scattered manner.

[0049] In the above embodiment, the light emitting device 10 is a line type that can emit light in a line shape. However, the light emitting device 10 is not limited to this. As shown in FIG. 7A, the light emitting device 10 may be a surface type (two-dimensional type) that can emit light in a plane by arranging the optical fibers 12 in a zigzag shape on a plate-shaped base material 131. The optical fibers may be arranged in a round spiral shape, a square spiral lightning pattern, a triangular spiral shape, or a character shape. With this configuration, unlike conventional light emitting devices using light emitting elements such as LEDs, electrical wiring is not required, so that the degree of freedom in the design of the arrangement of the optical fibers 12 that emit light is very large. The distribution of the emission intensity in the plane can be adjusted by the degree of bending or the bending position of the optical fibers 12 by the light extraction unit 132. When the optical fibers 12 are light diffusing fibers, the distribution of the emission intensity in the plane can be adjusted by the concentration of the scatterer added. In the surface type light emitting device 10, if the base material 131 is made of a light-transmitting material, it can emit light from both sides. 7B, the light emitting device 10 may be a three-dimensional type in which the optical fibers 12 are arranged two-dimensionally on each surface of a block-shaped base material 131. The base material 131 may be a cylindrical shape such as a rod shape, a cone shape, or the like.

[0050] In the above embodiment, a single light extracting member 13 is provided, but this is not particularly limited, and a configuration in which a plurality of line-type light extracting members 13 are provided in series along the length direction of a single optical fiber 12 may be used as shown in Fig. 8A, a configuration in which a plurality of surface-type light extracting members 13 are provided in series may be used as shown in Fig. 8B, or a configuration in which line-type and surface-type light extracting members are mixed and connected. This is effective for use as a display system with a high degree of freedom in layout changes.

[0051] In the above embodiment, the light extraction section 132 and the light reflection section 133 are each configured as independent structures, but this is not particularly limited to this, and the light extraction section and the light reflection section may be configured as an integrally formed structure, or the light extraction section and the light reflection section may be configured as a single structure having both functions.

[0052] In the above embodiment, the laser light source 11 is used, but the present invention is not limited to this, and other light sources may be used.

[0053] In the above embodiment, a single laser light source 11 and a single-core optical fiber 12 are used, but the present invention is not limited to this and may be configured to use a plurality of laser light sources and a plurality of optical fibers. By using a plurality of laser light sources and a plurality of optical fibers, it is possible to obtain light with a stronger emission intensity, and also to achieve multicoloring and improved visibility.

[0054] In the above embodiment, the optical fiber 12 is configured as a single-core fiber having a single core 121, but this is not particularly limited, and the optical fiber may be configured as a multi-core fiber having a plurality of cores.

[0055] In the above embodiment, the light extraction portion 132 is configured to be a cylindrical body, but is not particularly limited to this, and may be configured to be a polygonal prism such as a rectangle.

[0056] In the above embodiment, the optical fiber 12 is wound around the light extraction portion 132 to generate stress, but this is not particularly limited to this, and any configuration that generates stress in the optical fiber may be used, such as a configuration in which the optical fiber is pulled like a hook, a configuration in which it is fitted into a groove, a configuration in which it is glued to a substrate or the like, a configuration in which it is wound around a rod-shaped object, etc.

[0057] In the above embodiment, the optical fiber 12 is stressed by the light extraction unit 132 to cause light to leak from the core of the optical fiber 12. However, if the state in which light leaks from the core due to a stress once applied can be maintained, the light extraction unit 132 is not necessarily required. For example, a member for applying stress to the optical fiber 12 may be separately prepared, and the optical fiber 12 may be stressed to create a state in which light leaks from the core, and this state may be maintained at, for example, the softening temperature or glass transition temperature of the cladding or coating material, and then cooled to fix this shape. In this way, the effect of the present invention can be obtained even in the absence of the light extraction unit 132. The means for fixing the stressed state or shape is not limited to the above temperature, and ultraviolet irradiation or other methods are also possible. In this case, the means for fixing the stressed state or shape constitutes the light extraction means.

[0058] The direction of the stress generated in the optical fiber 12 may be either the length direction or the cross-sectional direction of the optical fiber 12.

[0059] In the above embodiment, the inclined surface of the flat surface of the light reflecting portion 133 is the light reflecting surface, but this is not particularly limited to this, and the light reflecting surface may be a curved surface or a free-form surface taking into account the light emission direction. EXAMPLES

[0060] (Measurement experiment on the relationship between the emission angle and the emission intensity of the side light emitted from an optical fiber) 9, an experimental device A was constructed in which the optical fiber 12 was provided to weave between a plurality of cylindrical light extraction parts 132 arranged at the apexes of a zigzag shape, and a silicon photodiode PD was provided to be movable around the apex of the bent part of the optical fiber 12 wound around a specific light extraction part 132. In addition, as the optical fiber 12, a fiber A with no scatterer added to the clad and a fiber B with a scatterer added to the clad were prepared, each having a core made of quartz, a clad made of silicone resin, and a coating layer made of fluororesin.

[0061] <Measurement 1> For fiber A, red (R) laser light was incident from the laser light source, and the silicon photodiode PD was used to measure the emission intensity of side emission at each emission angle in the range from an emission angle of -180° on the laser light incident side (rear) of the optical fiber 12 to an emission angle of 0° on the emission side (front) of the optical fiber 12, within a plane including the portion where the optical fiber 12 was bent into a wave shape by pressing the light extraction part 132. Similar measurements were also performed for green (G) and blue (B) laser light, and white (W) laser light which is a mixture of red (R), green (G), and blue (B). Similar measurements were also performed for fiber B.

[0062] 10A and 10B show the relationship between the emission angle and the emission intensity of fibers A and B, respectively, for this measurement 1. According to this result, it can be seen that side emission is observed in all directions of the measurement range. In addition, although there is a difference depending on the wavelength of the laser light, it can be seen that the amount of light is biased from the vertical emission angle of -90° to the forward direction regardless of whether or not a scatterer is added, and is particularly strong around the emission angle of -45°. In addition, in fiber B to which a scatterer is added, the peak around the emission angle of -45° is sharpened, which is thought to be influenced by the inherent characteristics of the scatterer itself. The design of the light reflecting part 133 is also simplified by concentrating energy around the emission angle of -45°. In addition, if the curvature of the bend of the optical fiber 12 is reduced and a larger stress is generated, all of these angles tend to shift slightly in the vertical direction.

[0063] <Measurement 2> As shown in FIG. 11, a similar measurement was performed in a plane perpendicular to the measurement plane in Measurement 1.

[0064] 12A and 12B show the relationship between the emission angle and the emission intensity of fibers A and B, respectively, for measurement 2. The results show that, unlike measurement 1, no strong emission intensity was observed at a specific emission angle, and the emission intensity was generally close to Lambertian radiation.

[0065] (An example of a light reflector design that takes into account the direction of light emitted from the side of an optical fiber) It is possible to control the output direction from a light-emitting device by designing the light reflector taking into account the output direction of side-emission light from the optical fiber. Since the output direction changes depending on the structure of the optical fiber and the configuration of the light extraction section, it is possible to design a desired light-emitting device by measuring the emission intensity in each output direction in advance. An example is shown below.

[0066] In the above measurement experiment, the optical fiber 12 was used, in which the core was made of quartz, the clad was made of silicone resin, and the coating layer was made of fluororesin, and strong emission intensity was confirmed near the emission angle of -45°, as described above. Using this, it is possible to design a structure that changes the optical path of side emission from the optical fiber to a direction perpendicular (upward) to the transmission direction of the laser light by the optical fiber. Specifically, as shown in Figures 13A and 13B, if the side emission emitted from the optical fiber 12 at an emission angle of -45° is designed to be perpendicularly incident on the light reflecting surface of the light reflecting section 133 with an inclination angle of 45°, it is possible to configure the side emission of the laser light from the optical fiber 12 to be changed in the optical path to a direction perpendicular to the transmission direction of the laser light of the optical fiber 12 and to be visually recognized.

[0067] In this way, it is possible to emit multiple side light emissions in any direction by designing the light reflecting surface 133 in consideration of the emission angle of the side light emissions of the optical fiber 12. For example, by individually designing each light reflecting surface, it is possible to easily realize a light emitting device that focuses or disperses multiple side light emissions in a specific direction.

[0068] In other words, a single light-emitting device has multiple side-emitting emission points, and by controlling each of them to a different emission angle, the desired radiation pattern can be constructed across the entire light-emitting device, which is similar to the operation of a phased array antenna. [Industrial Applicability]

[0069] The present invention is useful in the field of light emitting devices. [Explanation of symbols]

[0070] 10 Light-emitting devices 11 Laser light source 12 Optical Fiber 121 cores 122 Clad 123 Covering layer 13 Light extraction material 131 Base material 132 Light extraction section (light extraction means) 133 Light reflecting part (light reflecting means) 14 Embedded parts A. Experimental Equipment PD Silicon Photodiode

Claims

1. A light source; an optical fiber for transmitting light from the light source; a light extraction means for changing the extending direction of the optical fiber and generating stress in the optical fiber to cause side light emission; Equipped with the optical fiber has a core into which light from the light source is incident, and a cladding provided to cover the core, The cladding of the optical fiber is doped with a scatterer, The light emitting device further comprises an embedding member in which the optical fiber and the light extracting means are embedded.

2. A light source; an optical fiber for transmitting light from the light source; a light extraction means for changing the extending direction of the optical fiber and generating stress in the optical fiber to cause side light emission; Equipped with the optical fiber has a core into which light from the light source is incident, and a cladding provided to cover the core, The cladding of the optical fiber is doped with a scatterer, A plurality of the light extraction means are provided along the length direction of the optical fiber, The light-emitting device is configured such that the stress generated in the optical fiber at the light extraction means on the side away from the light source is greater than the stress generated in the optical fiber at the light extraction means on the side closer to the light source.

3. A light source; an optical fiber for transmitting light from the light source; a light extraction means for changing the extending direction of the optical fiber and generating stress in the optical fiber to cause side light emission; Equipped with the optical fiber has a core into which light from the light source is incident, and a cladding provided to cover the core, The cladding of the optical fiber is doped with a scatterer, the light extraction means is configured so that its position changes when an external force acts on it; A light emitting device configured such that, when the position of the light extracting means is changed, a stress generated in the optical fiber is changed, thereby changing the light emission intensity of the side light emission of the optical fiber.

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