KR101467387B1 - Surface light having the optical fiber - Google Patents

Abstract

The present invention relates to a surface light source using an optical fiber capable of emitting the light as surface light using the optical fiber and maintaining a flexible structure at the same time. The surface light source includes a substrate, the optical fiber which is received on the substrate, an optical device which is fixed to the substrate to emit the light to the end of the optical fiber, and a diffusion sheet which is composed of one or more silicon polymer layers in which inorganic particles are dispersed and mixed and is arranged on the substrate to cover the optical device.

Description

[0001] Surface light having the optical fiber [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a planar light source using an optical fiber that allows light to be emitted as a plane light using an optical fiber and maintains a flexible structure.

As is well known, a backlight unit (Back Light Unit) used for a monitor and a TFT-LCD, as well as a light exclusively for a surface light, is essentially constituted of a light guide plate and a diffusion sheet for allowing light to be emitted evenly in a plane.

For example, the backlight unit receives light emitted from a lamp using a transparent acrylic panel, uniformly distributes light over the entire area of the screen through a predetermined area and shape pattern deposited on the acrylic panel A reflective sheet positioned on the lower surface of the light guide plate to reflect the light exiting to the lower surface of the light guide plate back to the light guide plate and a reflective sheet disposed on the upper surface of the light guide plate to scatter light emerging from the surface of the light guide plate in a predetermined direction, A prism sheet for refracting and condensing light emitted from the diffusion sheet to increase the brightness; a protective sheet for preventing scratches and moiré phenomenon on the prism sheet; To form molds of the same type And a lamp reflector for blocking outflow of light generated from the lamp light source and reflecting the light escaping to the opposite side of the light guide plate and re-entering the light guide plate to maximize the efficiency of the lamp there was.

However, in the conventional planar light source configured as described above, a complicated process is required to form a certain pattern through printing or mechanical processing on the lower surface of the light guide plate so that the light guide plate directs the light coming from the lamp toward the front of the panel. In addition, since a large number of structures such as a light guide plate and a diffusion sheet (diffusion sheet) are required as described above, there is a problem in that competitiveness is inferior even at a manufacturing cost of a surface light source.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a planar light source using an optical fiber that simplifies a manufacturing process and a structure and further maintains a flexible light source structure.

According to an aspect of the present invention,

Board;

An optical fiber seated on the substrate;

An optical element fixed to the substrate to irradiate light to an end of the optical fiber; And

A diffusing sheet composed of at least one silicon polymer layer dispersed and mixed with inorganic particles and disposed on the substrate so as to cover the optical device;

Which is a surface light source using an optical fiber.

The present invention has the effect of increasing the luminous efficiency by increasing the luminous efficiency and minimizing the application structure for the variation by causing the point light source to be converted into the linear light by using the optical fiber and then being emitted as plane light through the diffusion sheet.

1 is a cross-sectional view schematically showing an embodiment of a planar light source according to the present invention,
2 is a perspective view schematically explaining an embodiment of a planar light source according to the present invention,
3 is a cross-sectional view showing an optical fiber configured in a planar light source according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It will be possible. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view schematically showing an embodiment of a planar light source according to the present invention, FIG. 2 is a perspective view schematically explaining an embodiment of a planar light source according to the present invention, Sectional view showing an optical fiber configured in a planar light source, which will be described with reference to FIG.

A planar light source according to the present invention includes a substrate 10, an optical fiber 20 mounted on the substrate 10, a base layer 30 laminated on the substrate 10 to cover and protect the optical fiber 20, A diffusion sheet 40 laminated on the base layer 30 to induce diffusion of light emitted from the optical fiber 20 and an optical element 20 for emitting light from the body of the optical fiber 20 by irradiating light to the end of the optical fiber 20 50).

The substrate 10 is a panel capable of uniformly arranging the optical fiber 20, and a PCB (Printed Circuit Board) or the like can be applied for mounting the optical element 50. Of course, since the optical element 50 can be separated from the substrate 10, the PCB 10 is not necessarily applied to the substrate 10.

In the meantime, the substrate 10 according to the present invention can be applied with a flexible material so that the surface light source according to the present invention may be warped.

For reference, the flexible substrate 10 is formed by forming a wiring pattern on a flexible insulating substrate made of a polymer such as polyimide, and various elements are mounted according to the type of the flexible substrate for a light source. In general, a flexible printed circuit board (FPCB) or a flexible copper clad laminate (FCCL) is exemplified.

The structure of the flexible substrate 10 will be described in detail with reference to an embodiment.

The copper foil pattern is bonded to the base polymer film, which is a flexible insulating substrate made of a polymer, with a copper foil adhesive layer. Examples of the adhesive used for the adhesive layer for copper foil include epoxy resin and phenol resin. The copper foil pattern is covered with an insulating protective film made of a polymer, and the insulating protective film is bonded to the copper foil pattern by an adhesive layer for an insulating protective film. However, one end of the copper foil pattern is exposed without being coated with the insulating protective film, and the exposed portion functions as a terminal portion for connecting to an external electronic component. Subsequently, the insulating protective film insulates the copper foil pattern from the outside, protects the copper foil pattern from corrosion such as rust, and enhances the folding endurance of the flexible substrate 10. As the material of the insulating protective film, polyimide is widely used. In order to stabilize the connection with an external electronic component by preventing the generation of rust of the copper foil pattern on the surface of the exposed portion (terminal portion) of the copper foil pattern, Au / Ni plating (Au layer after forming Ni layer in the lower layer ) Or Sn plating or the like is formed by plating.

The flexible substrate 10 may have various structures other than the above-described structure, and various techniques for improving flexural resistance may be applied.

In addition, since the optical fiber 20 is mounted on the substrate 10, a seating groove for stably mounting the optical fiber 20 can be formed. For reference, when the seating position of the optical fiber 20 is formed by forming the seating groove, the base layer 30 may be excluded from the planar light source according to the present invention.

The optical fiber 20 is mounted on the substrate 10 and receives light from the optical element 50 positioned at the end portion and emits the light from the main body portion. The structure of the optical fiber 20 according to the present invention will be described in more detail. The structure of the optical fiber 20 according to the present invention will be described in more detail. 3 (b)) is injected into the cladding layer 22 or the inner surface of the core layer 21 to form the optical fiber 20 (see FIG. 3A) or the impurity material 22b ). 3, light traveling in the longitudinal direction through the core layer 21 constituting the optical fiber 20 is scattered and emitted in a direction perpendicular to the longitudinal direction.

3 (a), the scratch groove 22a is formed in the end portion of the optical fiber 20 adjacent to the optical element 50 so that the light scattered and emitted through the optical fiber 20 is uniform And it is preferable that the optical element 50 and the optical element 50 are formed at a distance from each other.

The optical fibers 20 mounted on the substrate 10 may be arranged in various forms but the optical devices 50 may be arranged in a line on the edge of the substrate 10 and the substrate 10 may be made of a flexible material It is preferable that the plurality of optical fibers 20 are arranged in parallel to each other so that the surface light source according to the present invention can be smoothly bent without interference of the optical fibers 20. [

The base layer 30 prevents light leakage of the optical fiber 20 and facilitates stacking of the diffusion sheet 40 on the upper side. The base layer 30 is preferably a silicon polymer. The silicon polymer as the base layer 30 has excellent heat resistance to the heat generation of the optical element 50 and the upper diffusion sheet 40 is made of the silicon polymer so that the light utilization efficiency can be improved, It is possible to prevent the phenomenon of the above-mentioned problems.

The base layer 30 covers the upper portion of the optical fiber 20 to a thickness of less than 0.5 mm so that the optical fiber 20 is thick enough to be seated on the substrate 10, It is preferable from the viewpoint of efficiency. Meanwhile, the base layer 30 according to the present invention may also contain inorganic particles to further improve uniformity and heat resistance.

For reference, the planar light source according to the present invention can integrate the base layer 30 and the diffusion sheet 40 together. Such an integration process can be achieved by using roll-to-roll equipment, which is advantageous in mass production, simple in process, and excellent in productivity.

The diffusion sheet 40 is composed of a silicon polymer layer 41, 42 including inorganic particles 41a, 42a having a refractive index n1 or n2.

Roneun the n1 or solid particles (41a, 42a) having a refractive index n2 and the like can be used _{ZrO 2, SiO 2, Al 2} O 3, TiO 2, Y 2 O3, SnO 2, CeO 2. Roneun inorganic particles (41a) having a refractive index n1, and the TiO ₂ are preferred, roneun inorganic particles (42a) having a refractive index n2 that is joined Al ₂ O _3. More preferably a rutile structure of TiO ₂ , and alpha (a) -Al ₂ O ₃ . It has been experimentally confirmed that TiO ₂ and Al ₂ O ₃ are optimal combinations of the inorganic particles 41 a and 42 a dispersed in the corresponding silicone polymer layers 41 and 42 to improve the heat resistance and maximize the uniformity .

The refractive index of n1 is larger than the refractive index of n2, and the refractive index difference is preferably 0.5 to 3.0. Diffusion occurs due to the refractive index difference, and diffusivity becomes larger as the refractive index difference is larger. Such a difference in refractive index of 0.5 or more leads to a degree of optical uniformity that can prevent the light emitted from the optical fiber from being reflected or glazed.

Al ₂ O ₃ as a representative inorganic particles (42a) having a refractive index of said n2 is from 1.75 to 1.78, having a refractive index range of the refractive index range of TiO ₂ is 2.6 to 2.8 as a typical inorganic particles (41a) having a refractive index of the n1 I have.

On the other hand, as described above, the structure of the diffusion sheet 40 is preferably a silicon polymer. For use as the diffusion sheet 40, it may be designed to have a constant curvature according to the use form. To achieve this object, a silicone polymer having a flexible property is suitable. For reference, the silicon polymer constituting the silicon polymer layers 41 and 42 has excellent heat resistance to heat, and is therefore suitable for direct-type illumination.

Optical sheets such as a light guide plate and a prism sheet of a conventional LED lighting device were made of materials such as polymethyl methacrylate (PMMA) and polycarbonate (PC), which were vulnerable to heat, and therefore, they had to be installed at a certain distance from the LED light source. However, the silicon polymer layers 41 and 42 used in the present invention can be used integrally with the LED light source and the optical fiber 20, which are excellent in heat resistance and can be utilized as the optical device 50. Although such excellent heat resistance can be achieved by the characteristics of the silicon polymer layers 41 and 42 themselves, it is experimentally confirmed that the inorganic particles 41a and 42a have better heat resistance by dispersing them.

In addition, the inorganic particles 41a and 42a not only enhance the heat resistance, but also increase the refractive index of the entire silicon polymer layers 41 and 42. When the refractive index increases, the light utilization efficiency increases.

The size of the inorganic particles 41a and 42a having the n1 or n2 refractive index is preferably 5 to 75 nm. Depending on the type of the inorganic particles (41a, 42a) slightly different, but it is particularly preferable that the size of 5 to 75nm in the TiO ₂ and Al ₂ O _3. When the thickness is less than 5 nm, aggregation occurs between the particles, and when the particle diameter is more than 75 nm, the heat resistance and the uniformity effect are inferior. However, there is some difference in the content. In other words, the high refractive index inorganic particles (41a), such as TiO ₂ having a refractive index of n1 is one preferred 0.05wt% to 0.2wt%, the low-refractive-index inorganic particles (42a), such as Al ₂ O ₃ having a refractive index n2 is 5.0wt% By weight to 15.0% by weight. In order to more uniformly disperse the inorganic particles 41a and 42a such as TiO ₂ or Al ₂ O ₃ in the silicone polymer layers 41 and 42, a surface modifier or a dispersant may be additionally used.

The preferable ranges of the contents of the inorganic particles 41a having the n1 refractive index and the inorganic particles 42a having the n2 refractive index were calculated in a range in which heat resistance, light utilization efficiency and uniformity were all satisfied. The content of the inorganic particles 41a and 42a with respect to light utilization efficiency and uniformity is shown in the following examples. As a result of the test in a 250 oven for 24 hours, heat resistance was determined to be within the appropriate range of the content of the inorganic particles (41a, 42a) without any change in color, peeling, or cracking of the visual material. As a result of the punching test, all of the diffusion sheets 40 in the content range of the inorganic particles 41a and 42a did not peel off.

The individual thickness of the silicon polymer layers 41 and 42 including the inorganic particles 41a and 42a is preferably 0.2 to 1.0 mm. The thickness of the entire layer including the individual layers is preferably 2.0 mm to 10.0 mm. When the individual thickness is 0.2 mm or less, the inorganic particles 41a and 42a are difficult to be dispersed, the heat resistance is low and the peeling phenomenon easily occurs. When the individual thickness is 1.0 mm or more, the light utilization efficiency is low.

The silicon polymer layers 41 and 42 including the inorganic particles 41a and 42a use silicon polymers having the same constitution. Since the same material has the same composition, there is little interface reflection between the materials, and the light utilization efficiency is improved, and peeling does not occur in the punching. Further, it is not necessary to use a separate adhesive component to integrate the layers.

The diffusion sheet 40 made of a silicone polymer material containing the inorganic particles 41a and 42a is suitable for wedge-shaped illumination or direct-illumination type illumination. However, since the silicon polymer layers 41 and 42 including the present inorganic particles 41a and 42a have excellent heat resistance to the heat generation of the optical element 50 and have excellent light utilization efficiency while maximizing the uniformity, . In addition, it has an advantage of uniform light diffusion effect even when there is no separate light guide plate when applied to direct lighting.

The optical element 50 may be a halogen lamp, a cold cathode fluorescent lamp (CCFL), an LED, or the like as a means for irradiating the end of the optical fiber 20 with light.

The optical element 50 may be directly mounted on a circuit board formed at the edge of the substrate 10 or may be mounted on a circuit board separately formed from the substrate 10. [ The optical devices 50 may be paired with each other for each optical fiber 20 and one optical device 50 may be configured to irradiate the plurality of optical fibers 20 with light.

In the embodiment of the present invention, as shown in FIG. 2, the optical element 50 irradiates light for each optical fiber 20, thereby maximizing the optical efficiency of the optical fiber 20 based on the optical fiber 20.

Meanwhile, in order to efficiently transmit light between the optical element 50 and the optical fiber 20, the optical element 50 may be assembled to be received at the end of the optical fiber 20, As shown in the figure, a silicon polymer constituting the base layer 30 may be inserted between the optical element 50 and the optical fiber 20. As a result, the optical element 50 is integrally received in the base layer 30, and the emitted light is inserted into the end of the optical fiber 20 through the base layer 30, and the optical fiber 20, And emits in a direction perpendicular to the longitudinal direction as shown in Fig. 3 while moving light along the longitudinal direction.

Subsequently, the optical element 50 is buried in the base layer 30, so that the silicon polymer constituting the diffusion sheet 40 can be laminated on the flat base layer 30. For reference, the fence 11 may be reinforced in order to prevent the silicone polymer from escaping to the outside when the diffusion sheet 40 is laminated. The fence 11 is disposed to extend along the edge of the substrate 10 and functions as a mold until the silicon polymer constituting the base layer 30 and the diffusion sheet 40 is cured.

The light emitted from the optical element 50 is transmitted to the optical fiber 20 and the optical fiber 20 is emitted as the optical beam to the diffusion sheet 40, And performs the function of the surface light source by diffusing the linear light emitted from the optical fiber 20 in a plane light form.

<Experimental Example 1>

TiO ₂  And Al ₂ O ₃ Titration test of

The test sample was prepared by applying and firing a silicone polymer (base layer) so that the optical fiber 20 was thinly covered, applying and firing a silicon polymer (diffusion sheet) having the content of inorganic particles dispersed therein to be tested, x 4 cm in size. The uniformity and light efficiency tests were conducted using the model name 'RISA COLOR / ONE-S'.

Table 1 below shows the uniformity and the light utilization efficiency according to the content of TiO ₂ . The particle size of TiO ₂ was 50 nm, and the silicon polymer layers 41 and 42 forming the diffusion sheet 40 were tested as a single layer.

TiO ₂ content 0.5 wt% 0.2 wt% 0.1 wt% 0.05 wt% 0.01 wt% Uniformity 12.6 24.7 29.5 23.2 9.8 Light utilization efficiency 73.80 74.90 77.84 76.45 75.48

As shown in Table 1, when the content of TiO ₂ is 0.1 wt%, the uniformity and the light utilization efficiency are the highest, and when the content of TiO ₂ is 0.5 wt% and 0.01 wt% As shown in FIG. Therefore, when the content of TiO ₂ is 0.05 wt% to 0.2 wt%, the light diffusivity (uniformity) that minimizes the non-contact phenomenon or the glare phenomenon of the light source is shown and the excellent light use efficiency is shown.

Table 2 below shows the uniformity and the light utilization efficiency according to the content of Al ₂ O ₃ . The particle size of Al ₂ O ₃ was 70 nm, and the silicon polymer layers 41 and 42 forming the diffusion sheet 40 were tested as a single layer.

Al ₂ O ₃ content 20wt% 15wt% 10wt% 5 wt% 1wt% Uniformity 10.2 23.3 28.7 22.4 6.3 Light utilization efficiency 72.8 73.9 75.4 75.0 74.2

As shown in Table 2, when the content of Al ₂ O ₃ is 10 wt%, the uniformity and the light utilization efficiency are the highest, and when the content of Al ₂ O ₃ is 20 wt% and 1 wt% As shown in FIG. Therefore, when the content of Al ₂ O ₃ is in the range of 5 wt% to 15 wt%, the light diffusivity (uniformity) that minimizes the non-penetration phenomenon or the glare phenomenon of the light source is exhibited and the excellent light utilization efficiency is shown.

<Experimental Example 2>

Uniformity and light utilization efficiency test

Uniformity and light use efficiency test for grasping the degree of light diffusivity were carried out. The silicon polymer layers 41 and 42 constituting the diffusion sheet 40 were separated into a single layer and a multilayer (see FIG. 1). This test was conducted by coating and firing a silicon polymer base layer 30 containing 0.1 wt% TiO ₂ on an optical fiber 20 and applying and firing a diffusion sheet 40 thereon. The test was carried out so that the TiO ₂ content was 0.1 wt%, the Al ₂ O ₃ content was 10 wt%, and the SiO ₂ content was 10 wt%. The thickness of the single layer was 0.5 mm, and the test was carried out. The results are shown in Table 3 below.

Material single layer diffuser non SiO ₂ TiO ₂ Al ₂ O ₃ TiO ₂ + Al ₂ O ₃ Uniformity 1.7 21.6 32.5 34.4 22.7 Light utilization efficiency 85.4 82.2 84.7 83.3 79.7 Material multi layer diffuser TiO ₂ / Al ₂ O ₃ Al ₂ O ₃ / TiO ₂ (TiO ₂ + Al ₂ O ₃ ) x 2 (TiO ₂ / Al ₂ O ₃ ) x 2 _{(Al 2 O 3 / TiO 2} ) x2 Uniformity 51.9 54.3 43.1 88.5 88.1 Light utilization efficiency 81.2 79.9 73.7 77.3 74.2

TiO ₂ + Al ₂ O ₃ : A single layer diffusion sheet in which TiO ₂ and Al ₂ O ₃ are mixed.

TiO ₂ / Al ₂ O _3: TiO ₂ layer is close to the LED light source than Al ₂ O ₃ layer, consisting of two diffusion layers of TiO ₂ and Al ₂ O ₃ sheet

Al ₂ O ₃ / TiO ₂ : Al ₂ O ₃ layer is TiO ₂ A diffusion sheet made of two layers of Al ₂ O ₃ and TiO ₂ ,

(TiO ₂ + Al ₂ O ₃ ) x ₂ : A diffusion sheet in which two layers of a mixture of TiO ₂ and Al ₂ O ₃ are laminated.

(TiO ₂ / Al ₂ O ₃ ) x ₂ : A diffusion sheet in which the TiO ₂ layer is closer to the LED light source than the Al ₂ O ₃ layer and the layers of TiO ₂ and Al ₂ O ₃ are alternately laminated.

(Al ₂ O ₃ / TiO ₂ ) x ₂ : Al ₂ O ₃ layer is closer to the LED light source than the TiO ₂ layer, and Al ₂ O ₃ and TiO ₂ layers are alternately laminated.

From Table 3 above, five effects on the diffusion sheet of the present invention can be derived.

First, it can be seen that the diffusion sheet of the single layer of TiO ₂ and Al ₂ O ₃ of Table 3 is superior in uniformity and light utilization efficiency as compared with [Table 1] and [Table 2]. Table 1 and Table 2 and Table 3 of Test difference if it is the base layer, so a difference in whether or not contain TiO ₂ to 30, a base layer (30) containing the TiO ₂ Uniformity And the light utilization efficiency is more excellent.

Second, it can be seen that the uniformity of the multiple-layer diffusion sheet is superior to that of the single-layer diffusion sheet under the same conditions, and the uniformity of the four-layer diffusion sheet is superior to that of the two-layer diffusion sheet.

Third, it can be seen that the diffusion sheet containing TiO ₂ and Al ₂ O ₃ has better uniformity and light utilization efficiency than the diffusion sheet containing SiO ₂ .

Fourth, it can be seen that the diffusion sheet containing TiO ₂ and Al ₂ O ₃ as a single material is more uniform than the diffusion sheet containing TiO ₂ and Al ₂ O ₃ and the light utilization efficiency is better.

Fifth, TiO ₂ are alternately stacked in close proximity to the optical fiber 20 (TiO ₂ / Al ₂ O ₃₎ x2 diffusion sheet, Al ₂ O ₃ the optical fiber 20 close to the stack (Al ₂ O ₃ / TiO ₂ ) x ₂ diffusing sheet in terms of uniformity and light utilization efficiency.

As a result, the four-layered (TiO ₂ / Al ₂ O ₃ ) x 2 diffusing sheet 40 exhibits an optimal uniformity, and the effect of the surface light source state, that is, the effect of the optical fiber 20, And the glare phenomenon (glaring) can be minimized. In addition, it shows an excellent effect of 75% or more in terms of light utilization efficiency, and thus it is suitable for use as a diffusion sheet dedicated for surface light source using optical fiber 20.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10; Substrate 11; Fence 20; Optical fiber
21; A core layer 22; Cladding layer 30; Base layer
41, 42; Silicon polymer layers 41a, 42a; Inorganic particle
50; Optical device

Claims (9)

Board; An optical fiber seated on the substrate; An optical element fixed to the substrate to irradiate light to an end of the optical fiber; And a diffusion sheet made of at least one silicon polymer layer dispersedly mixed with inorganic particles and disposed on the substrate so as to cover the optical element,
Wherein the diffusing sheet comprises a first silicon polymer layer in which inorganic particles having a refractive index of n1 are mixed and dispersed and a second silicon polymer layer in which inorganic particles having a refractive index of n2 are mixed and dispersed and the refractive index of n1 is a refractive index ; And,
Inorganic particles having a refractive index n1 of the will of TiO _2, and wherein the content of the inclusion first silicon polymer layer 0.05wt% to 0.2wt%;
Wherein the surface light source is an optical fiber. Board; An optical fiber seated on the substrate; An optical element fixed to the substrate to irradiate light to an end of the optical fiber; And a diffusion sheet made of at least one silicon polymer layer dispersedly mixed with inorganic particles and disposed on the substrate so as to cover the optical element,
Wherein the diffusing sheet comprises a first silicon polymer layer in which inorganic particles having a refractive index of n1 are mixed and dispersed and a second silicon polymer layer in which inorganic particles having a refractive index of n2 are mixed and dispersed and the refractive index of n1 is a refractive index ; And,
Inorganic particles having a refractive index n2 of the above is that the Al ₂ O _3, and wherein the second silicon content contained within the polymer layer 5.0wt% to 15.0wt%;
Wherein the surface light source is an optical fiber. Board; An optical fiber seated on the substrate; An optical element fixed to the substrate to irradiate light to an end of the optical fiber; And a diffusion sheet made of at least one silicon polymer layer dispersedly mixed with inorganic particles and disposed on the substrate so as to cover the optical element,
Wherein the diffusing sheet comprises a first silicon polymer layer in which inorganic particles having a refractive index of n1 are mixed and dispersed and a second silicon polymer layer in which inorganic particles having a refractive index of n2 are mixed and dispersed and the refractive index of n1 is a refractive index ; And,
Wherein the diffusion sheet is formed by alternately stacking the first silicon polymer layer and the second silicon polymer layer to form four layers;
Inorganic particles having a refractive index of n1 are the TiO _2, the first is 0.05wt% to 0.2wt% in contained amount of silicon polymer layer, and;
Inorganic particles having a refractive index n2 of the above is that the Al ₂ O _3, and wherein the second silicon content contained within the polymer layer 5.0wt% to 15.0wt%;
Wherein the surface light source is an optical fiber. 4. The method according to any one of claims 1 to 3,
A base layer of a silicon polymer material laminated between the substrate and the diffusion sheet to embed the optical fiber;
Further comprising an optical fiber. 4. The method according to any one of claims 1 to 3,
The substrate may be a flexible printed circuit board (FPCB) or a flexible copper clad laminate (FCCL);
Wherein the surface light source is an optical fiber. 4. The method according to any one of claims 1 to 3,
A plurality of optical fibers arranged in parallel with each other;
Wherein the surface light source is an optical fiber. delete delete delete

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