TWI382204B - Optical diffusion plate and fabricating method thereof - Google Patents

Description

Light diffusing plate and manufacturing method thereof

The present invention relates to a light diffusing structure, and more particularly to a light diffusing plate and a method of fabricating the same.

In the liquid crystal display, in order to eliminate the light-type image of the light source (ie, the light tube) of the backlight module, a light diffusion structure is disposed to achieve the uniformity of the overall backlight module.

Conventional light diffusing structures are based on transparent optical resins such as poly(methylmethacrylate); PMMA, polycarbonate (PC), acrylate styrene (Methacrylate-co-Styrene) Copolymer; MS), polystyrene (PS) and other materials, mixed with a certain proportion of diffusion particles, and then formed into a diffusion substrate by die casting or extrusion molding, and then cut into the required size The required diffuser plate. A related art can be referred to U.S. Patent No. 6,723,772. However, the diffusion plate made by the manufacturing method is not efficient in light use. Therefore, in the use of the backlight module, one, two, or even two or more sheets must be used. Increase the directivity of the outgoing light to increase the front brightness. Furthermore, in the assembly of the backlight module, depending on the situation, it is necessary to use two sheets of enamel, and other functional films, such as a light diffusion film, a phase difference film, etc., the assembly process is long and complicated, and the enamel sheet is again For high cost components. As a result, the cost of the overall backlight module and the complexity of assembly increase.

In order to reduce the use of the ruthenium sheet, a ruthenium sheet and a light diffusion plate have been developed, and the functions of the two are integrally formed into a light diffusion structure.

In a conventional bismuth-integrated light-diffusing structure, it is mixed with respect to 100 parts by mass of a transparent resin with respect to 0.5 to 10 parts by mass of a cross-linked acrylic resin. A light diffusion sheet is formed; and a fine projected line having a zigzag cross section is formed on one surface of the light diffusion plate. The related art can be referred to Japanese Patent Laid-Open No. 09-304606.

Or, the light diffusion plate structure used in the direct type backlight module is directly used for transfer of the crucible. Related art can refer to China Patent Publication No. 200538810.

Another type of tantalum-integrated light-diffusing structure is formed by transferring a tantalum structure on the surface of an optical diffusing plate containing a light diffusing agent having a total light transmittance of 60% to 95%. With the function of the light diffuser. Related art can refer to China Patent Publication No. 200538766.

Although the prior art has been able to obtain a light diffusing structure having both a light diffusing film and a tantalum sheet. However, the thickness of the light diffusing structure produced is limited, and it is not sufficient to provide sufficient supporting force as a thick-walled light diffusing plate in medium and large liquid crystal displays (for example, 17 inches or more). Otherwise, the diffusing effect is too high, and the effect of collecting light due to the transfer cannot be exerted. Moreover, the conventional transfer method mostly uses the roll embossing, however, the shape that can be formed by the roll embossing is limited, and it is easy to cause uneven thickness of the finished product due to uneven force.

In addition, the surface hardness of most light diffusing plates is not good. For example, a light diffusing plate made of PC material has a pencil hardness of only 2B on the surface, so light diffusion occurs in subsequent cutting, packaging or assembly processes. The surface of the board is quite susceptible to damage. In particular, after the 稜鏡 structure is attached to the surface of the light diffusing plate, the fine junction of the surface of the light diffusing plate The structure (eg, 稜鏡 structure) is more likely to be scratched by metal or hard materials such as operators, dust or frames in the subsequent process, thereby damaging the product, resulting in an increase in the defect rate of the overall backlight module.

Furthermore, a diffusion structure having a surface structure tends to only improve the shielding ability, and has a limited effect on increasing the front brightness. Otherwise, its light extraction efficiency is limited.

In view of the above problems, it is a primary object of the present invention to provide a light diffusing plate and a method of fabricating the same, which solves the problems of the prior art.

The light diffusing plate disclosed in the present invention comprises: a light diffusing layer, a light collecting thin layer and a protective film.

The light diffusion layer, the light collecting thin layer and the protective film are sequentially disposed. In other words, the light diffusion layer and the protective film are respectively located on opposite surfaces of the light collecting thin layer. The light collecting thin layer is located on one surface of the light diffusing layer, and has a plurality of fine protrusions on a surface opposite to the other side of the light diffusing layer. The protective film is on the surface of the light collecting thin layer having fine protrusions to protect the surface structure on the light diffusing plate.

The method for fabricating a light diffusing plate according to the present invention comprises: forming a multilayer substrate on a bottom plate of the mold, wherein the multilayer substrate has a light diffusion layer, a light collecting thin layer and a protective film which are sequentially stacked on the bottom plate; Pressing a template of the mold from one side of the protective film of the multilayer substrate, wherein the template has a plurality of fine pits for contacting the surface of the protective film; and removing the mold from the multilayer substrate to obtain a light diffusing plate, wherein One side surface of the light diffusing plate has a plurality of fine protrusions corresponding to the fine pits.

In summary, the light diffusing plate according to the present invention can achieve an increase in light efficiency, a replica mirror structure and a protective surface structure, thereby increasing the optical diffusing material on a large-sized surface. The possibility of application on the backlight module of the board. Further, the manufacturing method of the light-diffusing sheet according to the present invention is integrally processed by film insertion molding (FIM), thereby simplifying the process and reducing the production cost.

Referring to "1A to 1C", a method of fabricating a light diffusing plate according to an embodiment of the present invention is shown, which is integrally processed by film insertion molding (FIM) to form a light diffusing plate 200. .

A multilayer substrate having a light diffusion layer 210, a light collecting thin layer 230, and a protective film 250 is provided on the bottom plate 110 of the mold, as shown in FIG. 1A. Here, the light diffusion layer 210, the light collection thin layer 230, and the protective film 250 may be sequentially formed on the bottom plate 110 of the mold. In other words, the light diffusion layer 210 is formed on the substrate 110, and then the light collection layer 230 is formed on the light diffusion layer 210 (ie, opposite to the other side of the substrate 110), and then on the light collection layer 230 (ie, relative to A protective film 250 is formed on the other side of the light diffusion layer 210. At this time, the light diffusion layer 210, the light collecting thin layer 230, and the protective film 250 are a material layer of a flat surface having substantially no grain on the surface (that is, without any unnaturally formed protrusions or cavities).

The thickness of the light diffusing layer 210 may be (or not limited to the present invention) 0.3 mm (cm) or more, and may be (but not limited to the present invention) up to 1.5 mm or more. For applications of medium or large size backlight modules, the thickness of the light diffusing layer 210 can be, but not limited to, between 0.3 mm and 2.0 mm.

Here, the light diffusion layer 210 may be formed by mixing the diffusion particles 214 in the transparent resin 212, and the transparent resin 212 and the diffusion particles 214 each have a different refractive index of light. Wherein, the material of the transparent resin 212 is optional (but not limited by the invention) Polymethylmethacrylate (PMMA), polycarbonate (PC), Methacrylate-co-Styrene copolymer (MS), polystyrene (PS) or Hydrogenated polystyrene, poly(ethylene terephthalate; PET), cycloolefin polymer (COP), or two or more of the foregoing resins mixture. The diffusion particles 214 may be a single type of particles, for example, (but not limited to the present invention) inorganic particles, organic particles or mixed particles, or a mixture of two or more of the above particles.

Further, the material of the transparent resin 212 and the diffusion particles 214 of the light diffusion layer 210 is appropriately selected so that the difference between the refractive index (n1) of the diffusion particles 214 and the refractive index (n2) of the transparent resin 212 is 0.05 to Between 0.25, that is, 0.05 ≧ (n1-n2) ≧ 0.25, the resulting light diffusing plate can obtain a better shielding ratio.

The light collecting thin layer 230 is formed on one surface of the light diffusion layer 210 by using a first resin material. Here, the thickness h of the light collecting thin layer 230 may be between 20 μm (micrometer) and 300 μm (but not limited by the present invention). Wherein, the first resin material may be (but not limited to) the transparent resin, and the transparent resin may be (but not limited to the invention) a thermoplastic resin, for example: (but not limited by the invention) polymethyl Methyl acrylate (PM), polycarbonate (PC), Methacrylate-co-Styrene copolymer (MS), polystyrene (PS) or hydrogenated styrene Polymer (Poogenated Polystyrene), poly(ethylene terephthalate); PET, cycloolefin polymer (COP), Or a mixture of two or more of the foregoing resins.

The protective film 250 is formed on one side surface of the light collecting thin layer 230 with respect to the light diffusing layer 210 by using a second resin material. This second resin material may be a transparent resin. Further, the transparent resin may be (but not limited to the invention) a thermoplastic and thermosetting resin, or a thermoplastic and photohardenable resin.

Moreover, the first resin material and the second resin material are appropriately selected such that the light refractive index (n3) of the light collecting thin layer 230 is larger than the light refractive index (n4) of the protective film 250, that is, n3>n4, which can be increased. The light-emitting efficiency of the light diffusing plate.

The template 130 of the mold is hot pressed from one side of the protective film 250, and the surface of the template 130 for contacting the protective film 250 has fine pits 132 as shown in FIG. 1B. During the hot pressing process, the light collecting thin layer 230 and the light diffusing layer 210 are welded together, and the protective film 250 and the light collecting thin layer 230 are welded together.

Here, the operating temperature of the mold may be between about 150 ° C and 300 ° C (but not the limit of the invention).

Referring to "1C", after the hot pressing, the mold is released, that is, the bottom plate 110 and the template 130 of the mold are removed from the light diffusing plate 200 to obtain a side surface having a fineness as shown in "1D". The light diffusing plate 200 of the protrusion 202. Corresponding to the pattern of the fine recess 132 on the surface of the template 130, the surface of one side of the light collecting layer 230 connected to the light diffusing layer 210 is also formed with fine protrusions 232. Further, the protective film 250 also has a sectional shape corresponding to the fine protrusions 232 of the light collecting thin layer 230.

In other words, the light diffusion layer 210 and the protective film 250 are respectively located on opposite surfaces of the light collecting thin layer 230. The light diffusion plate 200 has a side surface of one of the protective films 250 exhibiting fine protrusions 202.

The distance d between the tips of the adjacent fine protrusions 202 (equivalent to the fine protrusions 232 of the light collecting thin layer 230) may be about 50 micrometers (μm) (but not the limit of the present invention).

Further, if the second resin material is a thermosetting resin, after the heat pressing, the protective film 250 is hardened to form a hard coating film.

If the second resin material is a photocurable resin, it may be irradiated with light 300 of a specific wavelength after demolding or after the template 130 is removed to harden the protective film 250, as shown in "2 or 3". This ray 300 can be (but not limited by the invention) ultraviolet or radiant light, and the like.

Here, the protective film 250 has a certain degree of hardness so that the surface structure of the light diffusing plate 200 can be protected, for example, the fine protrusions 232 of the light collecting thin layer 230 are protected to avoid the assembly process during manufacturing or subsequent applications. The metal or hard material is scratched to damage the surface of the light diffusing plate 200. In other words, the cured protective film 250 can increase the surface structural hardness of the light diffusing plate 200.

In one embodiment, the cured protective film 250 may have a pencil hardness of 2H or more.

Here, the light diffusing plate 200 of various surface structures can be obtained by simply changing the surface pattern of the template 130. For example, various surface cross-sectional shapes (here, the cross-sectional shape composed of the fine protrusions 202) can be obtained by changing the sectional shape of the fine recess 132 of the template 130, for example: (but not the present invention) Restricted) A jagged, wavy, semi-wavy, etc., light diffusing plate 200, as shown in "1D, 4, and 5".

Furthermore, the surface pattern of the template 130 can also be changed (via changing the template) The top view of the fine recess 132 of 130 is used to obtain various surface patterns (here, the light diffusing plate 200 which is defined by the shape of the fine protrusions 202 in a plan view, for example, but not limited by the present invention, strips, braids, etc.) , as shown in Figures 6 and 7. In other words, the fine protrusions 202 of the light diffusing plate 200 (i.e., the fine protrusions 232 of the light collecting thin layer 230) may be (but not limited to the present invention) straight ribs or ridges or the like.

The light diffusing plate according to the present invention can be applied to a backlight module. In application, after the light source in the backlight module emits light, the light diffusion layer 210 is incident on the light diffusion layer 210 with respect to the other side surface of the light collection thin layer 230. After being homogenized by the diffusion action of the light diffusion layer 210, the light diffusion layer 210 is emitted adjacent to one surface of the light collection thin layer 230, and is incident on the light collection thin layer 230. The light from the light diffusion layer 210 is lifted by the light collecting action of the light collecting thin layer 230, and the light emitted from the light collecting thin layer 230 with respect to the other side surface of the light diffusing layer 210 (that is, the surface having the fine protrusions 232) is lifted. Brightness. Further, under the material of appropriately selecting the light collecting thin layer 230 and the protective film 250, the light extraction efficiency can be further increased.

Here, a light diffusing plate (hereinafter referred to as a finished product 1 and a finished product 2, respectively) produced in a conventional manner and a light diffusing plate produced according to the present invention (hereinafter referred to as Example 1 are respectively a finished product 3 and Finished product 4) Comparison of characteristics.

In this comparative test, the total light transmittance, haze, diffusivity, luminance uniformity, and hardness of the light diffusing plate were evaluated. Among them, the total light transmittance is based on the light transmittance measurement method described in ASTM D1003 of the American Society for Testing and Materials (ASTM) standard database, and is manufactured by NIPPON DENSHOKU CO., LTD. The turbidity meter of model NDH2000 was used for the measurement. The haze was measured using a haze meter of Model No. NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. based on the haze ratio measurement method described in ASTM D1003 of the ASTM Standards Database. The diffusion rate was measured using a two-dimensional variable angle photometer of Model GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. The uniformity of luminance is the use of Top Co., Ltd. of Japan Co., Ltd. TOPCON CORPORATION) The luminometer of the model BM7 manufactured was used for measurement, and the light diffusing plate was placed on the light box module parallel to each other between the cold cathode lamps. The hardness was measured using a pencil hardness tester based on the hardness measurement method described in ASTM D3363 in the ASTM Standards Database.

Preparation of optical diffusion colloid 1

A polycarbonate resin (PC) of the model Iupilon S2000UR produced by MITSUBISHI ENGINEERING-PLASTICS CORPORATION was prepared as a transparent resin. The polycarbonate resin has a total light transmittance of about 92%, a haze of <1%, and a diffusivity of <1%.

Further, a crosslinked styrene resin particle of model SBX-6 produced by SEKISUI PLASTICS CO., LTD. was prepared as a light diffusing agent. The crosslinked styrene resin particles have a particle diameter of about 6 μm to 10 μm.

100 parts by mass of the polycarbonate resin and 2 parts by mass of the crosslinked styrene resin particles were mixed in a mixer, and then granulated by a twin-screw compounding extruder (Model: ZSK-25, manufactured by Germany) to obtain light. Diffusion colloid 1.

Preparation of optical diffusion colloid 2

A polycarbonate resin (PC) of the model Iupilon S2000UR produced by MITSUBISHI ENGINEERING-PLASTICS CORPORATION was prepared as a transparent resin. This polycarbonate resin The total light transmittance is about 92%, the haze is <1%, and the diffusivity is <1%.

Further, a crosslinked phthalocyanine resin particle of the model MA1010 produced by Afakaken Co., Ltd. of Japan was prepared as a light diffusing agent. The crosslinked phthalocyanine resin particles have a particle diameter of about 6 μm to 10 μm.

100 parts by mass of the polycarbonate resin and 2 parts by mass of the crosslinked phthalocyanine resin particles were mixed in a mixer, and then granulated by a twin-screw compounding extruder (Model: ZSK-25, manufactured by Germany) to obtain light. Diffusion colloid 2.

Preparation of optical diffusion colloid 3

Acrylate styrene copolymer (MS) of model KM-2A produced by Nippon A&L IN CORPORATION was prepared as a transparent resin. The acrylate styrene copolymer (MS) resin has a total light transmittance of about 92%, a haze of <1%, and a diffusivity of <1%.

Further, a crosslinked styrene resin particle of model SBX-6 produced by SEKISUI PLASTICS CO., LTD. was prepared as a light diffusing agent. The crosslinked styrene resin particles have a particle diameter of about 6 μm to 10 μm.

100 parts by mass of an acrylate styrene copolymer (MS) resin and 2 parts by mass of crosslinked styrene resin particles are mixed in a mixer, and then a twin-screw compounding extruder (Model: ZSK-25, made in Germany) Granulation to obtain light-diffusing micelles 3.

Preparation of light diffusion layer

The light-diffusing colloidal particles 1 and the light-diffusing colloidal particles 2 were respectively formed into a thin plate at an operating temperature of 270 ° C using an injection molding machine (label: creator made in the USA, model: CI-110) to obtain a thickness of 2 mm. Light diffusion layer 1 and light diffusion layer 2.

The above light diffusing rubber pellet 3 is used in an injection molding machine (label: American creator, Model: CI-110) A thin plate was produced at an operating temperature of 230 ° C to obtain a light diffusion layer 3 having a thickness of 2 mm.

Optical measurement of light diffusion layer

The light diffusion layer 1 composed of a polycarbonate resin mixed with crosslinked styrene resin particles has a total light transmittance (TT) of about 86.13% and a haze of about 38.41%, and its diffusivity ( D _f ) is about 1.55%.

The light-diffusing layer 2 composed of a polycarbonate resin mixed with crosslinked phthalocyanine resin particles has a total light transmittance of about 80.96%, a haze of about 90.00%, and a diffusivity of about 29.05%.

The light-diffusing layer 3 composed of an acrylate styrene copolymer (MS) resin mixed with crosslinked styrene resin particles has a total light transmittance of about 80.45% and a haze of about 89.13%, and the diffusivity thereof. It is about 22.35%.

Preparation of light diffusing plate

The light-diffusing colloidal particles 3 obtained by the above method were placed in a drying apparatus of an injection molding machine (label: Huachin, made in Taiwan, model: HC-320), and dried at 80 ° C for 4 hours, and then the molded light was diffused. The layer (the operating temperature of the injection was 230 ° C) to obtain a finished product 1 having a thickness of 2 mm. That is, the light diffusing plate of the finished product 1 has only the light diffusing layer composed of the light diffusing rubber particles.

The light-diffusing rubber pellets 3 obtained by the above method were placed in a drying apparatus of an injection molding machine (brand: Huachin, made in Taiwan, model: HC-320), and dried at 80 ° C for 4 hours. Thereafter, the mold (having a size of about 15 Å) was placed on the injection machine, and the mold core (ie, the template) having the surface prism structure was fixed to the inside of the mold by vacuum suction. Then, the molded light diffusion layer is injected by the mold (the operating temperature of the injection) It is 250 ° C) to obtain a finished product 2 having a surface structure and a thickness of 2 mm. That is, the light diffusing plate of the finished product 2 has only the light diffusing layer composed of the light diffusing rubber particles, but the surface structure is formed on the surface of the light diffusing layer by the mold core.

The light-diffusing rubber pellets 3 obtained by the above method were placed in a drying apparatus of an injection molding machine (brand: Huachin, made in Taiwan, model: HC-320), and dried at 80 ° C for 4 hours. Thereafter, the mold (having a size of about 15 吋) is mounted on the injection machine, and the mold core (ie, the template) having the surface prism structure is fixed to the inner side of the mold by vacuum adsorption, and the transparent film is attached to the mold core. The surface of the prismatic structure. Then, the light diffusion layer was molded by a mold while the transparent film and the light diffusion layer were pressed (the operating temperature of the injection was 250 ° C) to obtain a finished product 3 having a surface structure and a thickness of 2 mm. Here, the transparent film is composed of a polycarbonate resin (ie, a light collecting thin layer) having a thickness of 188 μm and a plasticizable acrylate resin (ie, a protective film) having a thickness of 25 μm, and has a plasticized acrylate resin. One side contacts the surface of the mirror structure of the mold core. Therefore, the finished product 3 has a protective film, a light collecting thin layer, and a light diffusing layer which are sequentially laminated, and a surface structure is formed on the side having the protective film due to the mold core.

The polycarbonate resin of the transparent resin (label: Mitsubishi Engineering Plastics Co., Ltd., model: Iupilon S2000UR) was placed in a drying apparatus of an injection molding machine and dried at 80 ° C for 4 hours. Thereafter, the mold (having a size of about 15 吋) is mounted on the injection machine, and the mold core (ie, the template) having the surface prism structure is fixed to the inner side of the mold by vacuum adsorption, and the transparent film is attached to the mold core. The surface of the prismatic structure. Then, the light diffusion layer is formed by a mold and the transparent film and the light diffusion layer are simultaneously pressed (the operating temperature of the injection is 270 ° C) to obtain a surface. Finished product 4 having a face structure and a thickness of 2 mm. Here, the transparent film is the same as the finished product 3, and is composed of a polycarbonate resin (ie, a light collecting thin layer) having a thickness of 188 μm and a plasticizable acrylate resin (ie, a protective film) having a thickness of 25 μm, and has plasticization. One side of the molded acrylate resin contacts the surface of the prism structure of the mold. Therefore, the finished product 4 has a protective film, a light collecting thin layer, and a light diffusing layer which are sequentially laminated, and a surface structure is formed on the side having the protective film due to the mold core.

Here, the mold is produced by electroforming, and has a size of 306 mm long and 15 mm wide by 233 mm, and has a mold core having a surface of a prismatic structure.

Determination of characteristics of light diffusing plate

The properties of the finished product 1 and the finished product 2 obtained in a conventional manner, and the finished product 3 and the finished product 4 obtained according to the present invention, are shown in Table 1 below.

Among them, the TT system represents the total light transmittance, the Haze system represents the haze, and the D _f represents the diffusivity.

As can be seen from "Table 1," light diffusing sheets (such as finished product 3 and finished product 4) having a protective film can have a high surface hardness. Moreover, under the conventional technique, the formation of a surface structure containing diffusion particles (i.e., a ruthenium structure) (e.g., the finished product 2) can increase the diffusivity but does not increase the front luminance, but at the same time causes a decrease in the total light transmittance.

The light diffusing plate according to the present invention can achieve an increase in light efficiency, a replica mirror structure and a protective surface structure, thereby increasing the possibility of application of the optical diffusing material to a backlight module of a large-sized panel. Further, the manufacturing method of the light-diffusing sheet according to the present invention is integrally processed by film insertion molding (FIM), thereby simplifying the process and reducing the production cost.

While the present invention has been described above in terms of the preferred embodiments thereof, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The patent protection scope of the invention is subject to the definition of the scope of the patent application attached to the specification.

110‧‧‧floor

130‧‧‧ template

132‧‧‧Small pits

200‧‧‧Light diffuser

202‧‧‧Small protrusions

210‧‧‧Light diffusion layer

212‧‧‧Transparent resin

214‧‧‧Diffusion particles

230‧‧‧Light collection thin layer

232‧‧‧Small protrusions

250‧‧‧Protective film

300‧‧‧Light

D‧‧‧distance

H‧‧‧thickness

1A to 1C are schematic flow charts of a method of fabricating a light diffusing plate according to an embodiment of the present invention; FIG. 1D is a schematic cross-sectional view of a light diffusing plate according to a first embodiment of the present invention; FIG. 3 is a schematic diagram showing one step in a method of fabricating a light diffusing plate according to another embodiment of the present invention; FIG. 3 is a schematic diagram showing a step in a method of fabricating a light diffusing plate according to still another embodiment of the present invention; ; 4 is a schematic cross-sectional view of a light diffusing plate according to a second embodiment of the present invention; FIG. 5 is a schematic cross-sectional view of a light diffusing plate according to a third embodiment of the present invention; and FIG. 6 is a view according to the present invention A schematic plan view of a light diffusing plate of a fourth embodiment; and a seventh plan view showing a light diffusing plate according to a fifth embodiment of the present invention.

200‧‧‧Light diffuser

202‧‧‧Small protrusions

210‧‧‧Light diffusion layer

230‧‧‧Light collection thin layer

232‧‧‧Small protrusions

250‧‧‧Protective film

D‧‧‧distance

H‧‧‧thickness

Claims (14)

A light diffusing plate comprising: a light diffusing layer comprising a transparent resin and a plurality of diffusing particles dispersed in the transparent resin; a light collecting layer on a surface of the light diffusing layer, a light collecting thin layer having a plurality of fine protrusions on a surface of the other side of the light diffusing layer; and a protective film on the surface of the light collecting thin layer having the fine protrusions, and closely bonding the light collecting thin layer to have the same The surface of the fine protrusions. The light diffusing plate of claim 1, wherein the protective film has a sectional shape corresponding to the fine protrusions. The light diffusing plate of claim 1, wherein the fine protrusions are ridges. The light diffusing plate of claim 1, wherein the tips of the adjacent fine protrusions are apart by about 50 micrometers (μm). The light diffusing plate of claim 1, wherein the protective film has a pencil hardness of 2H or more. The light diffusing plate according to claim 1, wherein the light collecting refractive index of the light collecting thin layer is larger than the light refraction of the protective film. The light diffusing plate of claim 1, wherein the light collecting thin layer has a thickness of between 20 μm and 300 μm. The light diffusing plate of claim 5, wherein a difference in refractive index between the diffusing particles and the transparent resin is between 0.05 and 0.25. The light diffusing plate according to claim 1, wherein the light collecting layer and the light collecting layer The light diffusion layer is welded. The light diffusing plate of claim 1 or 9, wherein the protective film is welded to the light collecting thin layer. A method of fabricating a light diffusing plate according to claim 1, comprising: providing a multilayer substrate in a mold, wherein the multilayer substrate has a layer of light sequentially laminated on a bottom plate of the mold a diffusion layer, a light collecting layer and a protective film, wherein the light diffusion layer comprises a transparent resin and a plurality of diffusion particles dispersed in the transparent resin; and a template of the mold is used from the multilayer substrate One side of the protective film is hot pressed, wherein the template has a plurality of fine pits for contacting the surface of the protective film; and the mold is removed from the multilayer substrate to obtain a light diffusing plate, wherein the light One side surface of the diffusing plate has a plurality of fine protrusions corresponding to the fine pits, wherein the protective film closely engages the surface of the light collecting thin layer having the fine protrusions. The method of fabricating a light diffusing plate according to claim 11, wherein the hot pressing step comprises: performing hot pressing at an operating temperature of between 150 ° C and 300 ° C. The method for fabricating a light diffusing plate according to claim 11, wherein the step of forming the multilayer substrate comprises: forming the light diffusing layer on the bottom plate; forming the light collecting layer on the light diffusing layer And forming the protective film on the light collecting layer; wherein the light diffusing layer, the light collecting thin layer and the surface of the protective film are flat. The method for fabricating a light diffusing plate according to claim 11, further comprising: hardening the protective film after the hot pressing is completed.