TWI397723B - Process and apparatus of optical sheet and backlight module - Google Patents

Description

Optical thin plate, manufacturing method thereof and backlight module used thereby

The present invention relates to an optical sheet, and more particularly to an optical sheet capable of converging incident light, a method of fabricating the same, and a backlight module using the optical sheet.

The common direct type backlight module is mainly used for a larger size liquid crystal display. The direct type backlight module is disposed under the optical sheet directly under the optical sheet, and is thus the most characteristic. Please refer to FIG. 1. FIG. 1 is a schematic diagram of a direct type backlight module of the Republic of China Patent No. I264596. The direct type backlight module (1) includes a frame (11), a light source device (12), and a lamp cover ( 13) and a Fresnel lens (14). As shown in Fig. 1, after the light is output from the light source device (12), a portion is directly incident on the Fresnel lens (14), and the other portion is reflected by the lamp cover (13) and indirectly incident on Fresnel. Lens (14). The Fresnel lens (14) is used to converge the optical path to produce a focus of light, so that all rays incident on the Fresnel lens (14) are output parallel from the light exit surface (14A). However, the direct type backlight module (1) using the Fresnel lens (14) does not select the angle at which the light is incident and the direction in which the light travels, so the light energy generated by the light source device (12) cannot be fully utilized.

Therefore, how to increase the direct-type backlight module using the Fresnel lens for providing a uniform optical effect of a large-area liquid crystal panel is an object of ordinary skill in the art.

The main object of the present invention is to provide a direct-type backlight module with uniform optical effects, thereby providing a large-area liquid crystal panel having a directional optical path.

The invention provides an optical sheet for receiving incident light projected by a light source, comprising a body, a plurality of reflective structures and a plurality of Fresnel lens units. The body includes a corresponding one of the light incident surface and a light exiting surface, the light incident surface receives the incident light and has an incident angle with the incident light, the body having at least a refractive index n _i , i Is a positive integer. A plurality of reflective structures are located in the body, and two adjacent reflective structures are spaced apart by a distance W, and each of the reflective structures has a thickness t along a direction in which the incident light is incident. Each Fresnel lens unit is located on the light-emitting surface, and the Fresnel lens unit defines a width P along a direction of the light-emitting surface, and each of the Fresnel lens units corresponds to the pitch. When the formula is met: When j≧1, the incident light passes through the pitch, and the incident angle is adjusted by the thickness t, and the optical path of the incident light is converged by the plurality of Fresnel lens units.

The optical sheet as described above, wherein the system is only a polyethylene terephthalate (PET), a polycarbonate (PC), a triacetate (Tri-acetyl Cellulose). , TAC), Polymethylmethacrylate (PMMA), Methylmethacrylate styrene, Polystyrene (PS) or a cyclic olefin copolymer (Cyclic) Olefin Copolymer, COC) material or stack at least any two or more different Material.

The optical sheet as described above, wherein each of the Fresnel lens units further includes a plurality of Fresnel lens bodies, and each Fresnel lens body has a first end point and a second end point, The Fresnel lens body and the other Fresnel lens body are respectively located on two sides of the second end point, and the plurality of first end points are substantially aligned to form a straight line, and the second end point is spaced from the straight line by a height, The heights of the adjacent second end points are unequal, and the heights of the first end points of the two adjacent Fresnel lens units are equal.

The optical sheet as described above, wherein the ratio of the pitch W to the width P is in the range of 0.2 to 0.5.

The optical sheet as described above, wherein the light-emitting surface is spaced apart from the light-incident surface by a distance T, and the ratio of the distance T to the width P is in the range of 0.8 to 1.2.

The optical sheet as described above, wherein the reflective structures are made of a compound of titanium dioxide, germanium dioxide or magnesium monoxide.

The invention provides a method for manufacturing a cured optical sheet, the method comprising the steps of: first providing a transparent substrate having an upper surface and a lower surface, a curing glue, a mold, and a plurality of reflecting structures. Further, the cured adhesive is applied to the upper surface. A plurality of patterns on the surface of the mold are used to imprint the cured glue to produce a plurality of corresponding Fresnel lens units. Next, a plurality of Fresnel lens units on the cured glue are hardened. Finally, a plurality of reflective structures are combined on the lower surface.

The method for manufacturing a cured optical sheet as described above, wherein the cured adhesive is a UV curable resin or a thermal-plastic resin.

The present invention provides a method for manufacturing an extrusion molding of an optical sheet, the steps comprising: first providing a transparent substrate having an upper surface and a lower surface, a mold, and a plurality of reflective structures. Further, the mold is applied with a plurality of patterns on the surface thereof to emboss the transparent substrate to produce a plurality of Fresnel lens units corresponding to the upper surface of the transparent substrate. Finally, a plurality of reflective structures are bonded to the lower surface of the transparent substrate.

The extrusion molding manufacturing method or the curing manufacturing method of the optical sheet as described above, wherein the transparent substrate is only a polyethylene terephthalate (PET), a polycarbonate (Polycarbonate, PC), a Tri-acetyl Cellulose (TAC), Polymethylmethacrylate (PMMA), Methylmethacrylate styrene, Polystyrene (PS) ) or a Cyclic Olefin Copolymer (COC) material or a stack of at least two or more different materials.

The extrusion molding manufacturing method or the curing manufacturing method of the optical sheet as described above, wherein the mold is a roller or a flat mold.

The extrusion molding manufacturing method or the curing manufacturing method of the optical sheet as described above, wherein the bonding step of the plurality of reflective structures is a bonding method or a screen printing method.

The invention provides a backlight module comprising a plurality of light source devices, an optical film and an optical sheet. Wherein, a plurality of light source devices are used to generate an incident light. The optical film is disposed on the other side of the optical sheet relative to the light source device for correcting the optical path of the incident light. The optical sheet is configured to receive incident light projected by the light source device, and includes a body, a plurality of reflective structures, and a plurality of Fresnel lens units. The body includes a corresponding one of the light incident surface and a light exiting surface, the light incident surface receives the incident light and has an incident angle with the incident light, the body having at least a refractive index n _i , i Is a positive integer. A plurality of reflective structures are located in the body, and two adjacent reflective structures are spaced apart by a distance W, and each of the reflective structures has a thickness t along a direction in which the incident light is incident. Each Fresnel lens unit is located on the light-emitting surface, and the Fresnel lens unit defines a width P along a direction of the light-emitting surface, and each of the Fresnel lens units corresponds to the pitch. When the formula is met: When j≧1, the incident light passes through the pitch, and the incident angle is adjusted by the thickness t, and the optical path of the incident light is converged by the plurality of Fresnel lens units.

The backlight module as described above, wherein the light source device is a cold cathode fluorescent lamp (CCFL), a light emitting diode (LED), a planar light source (FFL), and an external electrode fluorescent lamp (EEFL). ) or a hot cathode fluorescent tube (HCFL).

Thereby, the optical sheet of the present invention or the backlight module using the optical sheet can provide greater light intensity and better collimating ability to enhance better optical performance.

The present invention will be described in detail by the following detailed description of the embodiments of the invention and the accompanying drawings.

Please refer to FIG. 2. FIG. 2 is a schematic view showing an embodiment of an optical sheet of the present invention. The optical sheet (24) is for receiving incident light and producing a light focusing effect by changing the optical path of the incident light. The optical sheet (24) includes a body (241), a plurality of Fresnel lens units (242), and a plurality of reflective structures (243). The body (241) includes a corresponding one of the light incident surface (241B) and a light exiting surface (241A) for receiving incident light, and the incident light is incident on the light incident surface ( 241B) is an incident angle. The body (241) has a refractive index n _i , i is a positive integer, and can be made of a single material (i = 1 at this time) or at least two or more (i> 1) different refractive indices n _i of different materials. Stacking, which is usually made of Polyethylene Terephthalate (PET), Polycarbonate (PC), Tri-acetyl Cellulose (TAC), and a poly Polymethylmethacrylate (PMMA), Methylmethacrylate styrene, Polystyrene (PS) or Cyclic Olefin Copolymer (COC) Light transmissive material. A Fresnel lens unit (242) is located on the light exiting surface (241A) for focusing the incident light; each Fresnel lens unit (242) has the same structural shape, thereby being composed of a plurality of The combination of the Fresnel lens unit (242) allows the optical sheet (24) of the present invention to be applied to a large-sized liquid crystal panel. The material of the plurality of reflective structures (243) may be a compound of titanium dioxide, germanium dioxide or magnesium monoxide. A plurality of reflective structures (243) are disposed on a light incident surface (241B) side of the body (241), and two adjacent reflective structures (243) are spaced apart by a distance W, and each reflective structure (243) is incident along the incident light. The direction has a thickness t, and the light exit surface (241A) of the optical thin plate (24) is spaced apart from the light incident surface (241B) by a distance T, and the Fresnel lens unit (242) is elongated along the body (241). Defining a width P; when the incident light passes through the distance between the plurality of reflective structures (243), the incident angle of the light can be adjusted by the thickness t, and the incident light is further reflected by the plurality of Fresnel lens units (242) The optical path converges to achieve the purpose of focusing on the light, if the formula is satisfied: When j≧1, the optical sheet (24) can obtain a uniform light intensity from a vertical viewing angle and a horizontal viewing angle.

In order to give a person skilled in the art a clearer understanding of the technical features of the optical sheet of the present invention, the structure and focusing principle of the Fresnel lens unit will be explained in more detail herein. Please refer to FIG. 2 and FIG. 3A simultaneously. FIG. 3A is a schematic view showing the first embodiment of the Fresnel lens unit of the optical sheet of the present invention. As shown in FIG. 3A, the Fresnel lens unit (242) is an aberrance lens whose optical effect is equivalent to that of a general convex lens and can be used for focusing light. The advantage is that the Fresnel lens is thinner and more weight than the convex lens. Light, helps with installation settings on the mechanical structure. The Fresnel lens unit (242) includes a plurality of Fresnel lens bodies (2421), and the Fresnel lens bodies (2421) have different appearances; each Fresnel lens body (2421) has a The first end point (2421A) and a second end point (2421B), and the two Fresnel lens bodies (2421) are respectively located on two sides of the second end point (2421B). The plurality of second end points (2421B) are arranged substantially to form a straight line of the same height, the first end point (2421A) is at a height from the line, and the heights of the two adjacent first end points (2421A) are not equal. In addition, each Fresnel lens body (2421) further includes a first refractive surface (2421C) and a second refractive surface (2421D), the first refractive surface (2421C) and the second refractive surface The faces (2421D) respectively have a first angle (θ 1) and a second angle (θ 2) with respect to the horizontal line. Each Fresnel lens body (2421) mainly uses the plurality of first refractive surfaces (2421C) to focus the incident light, and the first refractive surface (2421C) refracts the incident light (L1) to make the light (L1) After the refraction, the light output surface (241A) is output vertically. The first refractive surface (2421C) may be a curved surface type, but for the convenience of the process, it may be replaced by a planar type, and the planar first refractive surface (2421C) does not greatly affect the focusing function of the optical thin plate (24). In addition, the second refractive surface (2421D') of the conventional Fresnel lens is a vertical plane, and the second refractive surface (2421D') of the vertical type is shown here by a broken line; and in order to save the process, the first The two refractive surface (2421D) is inclined, and the second refractive surface (2421D) of the inclined pattern is shown by a solid line. The second type of refraction surface (2421D') of the conventional type is too large, and the incident light (L2) is totally reflected, so that the output light (L2) cannot be output to the light exit surface (241A), so that the light energy is wasted; The second refractive surface (2421D) of the present invention moderately adjusts the incident angle, and the light (L3) incident in the same direction is outputted in a refracting manner, so that the light (L3) is vertically outputted to the light surface (241A), so that the light energy is fully utilized. In the Fresnel lens unit (242), a plurality of Fresnel lens bodies (2421) distributed at different positions are included, and these Fresnel lens bodies (2421) have different contours to make these first angles (θ) The size of 1) varies with the location of the distribution.

The optical sheet as described above can increase the light intensity of the light emitted therefrom and improve the optical properties of the conventional optical sheet. In order to disclose the effects desired by the present invention, the inventors conducted a plurality of performance experimental tests based on the structural features of the optical sheets to confirm the progress of the present invention.

First, please refer to FIG. 5. FIG. 5 illustrates the optical sheet of the present invention. Optical performance test chart under different T/P values, which is an optical simulation test for the ratio of the distance T to the width P of the Fresnel lens unit, to show that the optical sheet is presented under different simulation parameters. Optical performance. As shown in FIG. 5, the abscissa indicates a different viewing angle between -90 and +90 degrees, and the ordinate is a Light Intensity value. When the T/P value is 0.6, the optical intensity of the optical sheet is about 300 candelas; but when the T/P value is 0.6 to 1.2, the optical intensity of the optical sheet can reach 375 canons or more, and T/ is used therein. When the P value is 1.0, the optical sheet has a light intensity of about 500 candles. Therefore, the optimum range of the ratio of the distance T to the width P is 0.8 to 1.0.

Referring to FIG. 6 , FIG. 6 is a diagram showing the optical performance test of the optical sheet of the present invention under different aperture ratios, which is directed to the aperture ratio of the reflective structure (opening ratio, the spacing between the reflective structures and the phenanthrene). The optical performance test chart of the ratio of the width P of the neel lens unit is used to display the light intensity values of the optical sheets at different viewing angles between -90 and +90 degrees. As shown in FIG. 6, the light intensity when using a conventional brightness enhancement film (BEF) is less than about 400 candles; and the optical sheet of the present invention is tested for performance by adjusting the structural size ratio of the optical sheet. When the aperture ratio (W/P value) is 0.2~0.5, the optical intensity of the optical sheet is slightly higher than the conventional brightness enhancement film and reaches 400~450 candlelight; if the aperture ratio is 0.2, the light intensity can be reached. 600 candelas. Therefore, from the simulation, the optimum range of the ratio of the pitch W to the width P is 0.3 to 0.4.

Referring to FIG. 7, FIG. 7 is a comparison diagram of optical performance tests of an optical sheet using a Fresnel lens (Fresnel Len) and a conventional brightness enhancement film according to the present invention. As shown in FIG. 7, the curve of the Fresnel lens represents the simulation data of the general vertical second refractive surface, and the curve of the modified Fresnel lens. It is analog data representing the inclined second refractive surface. It can be seen from Fig. 7 that the light intensity when using the conventional brightness enhancement film is less than about 400 canons; and the optical intensity of the optical sheet using the Fresnel lens is higher than that of the conventional brightness enhancement film, and the correction of the inclined second refractive surface The Fresnel lens has a light intensity of up to about 500 candles. The physical significance of the simulation data in Figure 7 is that the collimated ability of an optical sheet using a Fresnel lens is 10 to 30% higher than that of a conventional brightness enhancement film. Therefore, the effects achieved by the structural features of the present invention are known from this experiment.

Next, for the reflective structure, the angle at which incident light is incident can be adjusted by its thickness t; here, the inventors provide a formula for limiting the structural features of the optical sheet of the present invention: , j≧1, when the structural characteristics of the optical sheet satisfy the above formula, the optical sheet of the present invention can be made to have a better light intensity. The optical performance test of the experimental parameters satisfying the above formula limits is shown in FIG. 8. FIG. 8 is a graph showing the optical performance of the optical sheet of the present invention under different reflective structure thickness conditions. It can be seen from Fig. 8 that the reflection structure can satisfy the formula requirement from 20um to 500um (micrometer), and the light intensity of the optical sheet can reach 450~500 candelas.

Finally, in order to further demonstrate that the optical performance of the present invention is superior to conventional brightness enhancing films, the optical energy output by the optical sheet of the present invention is divided into a vertical viewing angle and a horizontal viewing angle. Please refer to FIG. 9 and FIG. 10. FIG. 9 is a comparison diagram of optical performance tests of the optical thin plate of the present invention and a conventional brightness enhancement film in a vertical viewing angle, and FIG. 10 illustrates the optical thin plate of the present invention and a conventional brightness enhancement film. Comparison of optical performance tests in horizontal viewing angles. 9 and FIG. 10, it can be found that the optical sheet of the present invention can be obtained from both a vertical viewing angle and a horizontal viewing angle. The large light intensity shows that the concentrating ability of the present invention is superior to that of the conventional brightness enhancing film. In addition, in the comparison chart of Fig. 10, it can be found that the horizontal viewing angle of the present invention is wider than that of the conventional brightness enhancing film.

In addition, a backlight module using the above optical sheet is disclosed herein, and those skilled in the art will more clearly understand the application of the present invention. Please refer to FIG. 2, FIG. 3A and FIG. 4 simultaneously. FIG. 4 is a schematic diagram of an embodiment of a backlight module using an optical thin plate according to the present invention. In FIG. 4, the same components as those in FIG. 2 and FIG. 3A will not be described herein. As shown in FIG. 4, the backlight module (2) includes a frame (21), a plurality of light source devices (22), an optical sheet (24), and an optical film (25). The frame (21) is for supporting the optical sheet (24) and accommodating the light source devices (22). The light source device (22) can be a cold cathode fluorescent lamp (CCFL), a light emitting diode (LED), a planar light source (FFL), an external electrode fluorescent lamp (EEFL) or a hot cathode. Fluorescent tube (HCFL); the light output from the light source means (22) is incident on the inside of the optical sheet (24) from the distance between the reflective structures (243), and after focusing by the Fresnel lens unit (242), The light is output perpendicular to the light exit surface (241A), and the optical path of the light is corrected by the optical film (25).

Next, another embodiment of a Fresnel lens unit of an optical sheet is disclosed herein. Please refer to FIG. 3B. FIG. 3B is a schematic view showing a second embodiment of the Fresnel lens unit of the optical sheet of the present invention. As shown in Fig. 3B, the Fresnel lens unit (342) employs a Fresnel lens for focusing light. The Fresnel lens unit (342) includes a plurality of Fresnel lens bodies (3421), each Fresnel lens body (3421) having a first end point (3421A) and a second end point (3421B). And two Fresnel lens bodies (3421) are respectively located on two sides of the second end point (3421B). many The first end points (3421A) are arranged substantially to form a straight line of the same height, the second end point (3421B) is at a height from the line, and the heights of the two adjacent second end points (3421B) are not equal. This embodiment can achieve the same function as the Fresnel lens unit (242) of the first embodiment described above by this different structure.

Next, a method of producing a cured optical sheet of the present invention will be described. First, the steps include: providing a transparent substrate having an upper surface and a lower surface, a curing adhesive, a mold, and a plurality of reflective structures; wherein the mold can be a roller or a flat mold. The curing adhesive can be a UV curable resin or a Thermal-plastic resin. Further, the cured adhesive is applied to the upper surface. A plurality of patterns on the surface of the mold are used to imprint the cured glue to produce a plurality of corresponding Fresnel lens units. Next, a plurality of Fresnel lens units on the cured glue are hardened. Finally, an optical sheet as described above can be produced by combining a plurality of reflective structures on the lower surface by a paste or screen printing method.

Of course, those skilled in the art can also fabricate the optical sheet described above by using an optical sheet extrusion molding method, the steps comprising: first providing a transparent substrate having an upper surface and a lower surface, a mold, and a plurality of reflective structures. . Further, the mold is applied with a plurality of patterns on the surface thereof to emboss the transparent substrate to produce a plurality of Fresnel lens units corresponding to the upper surface of the transparent substrate. Finally, by combining a plurality of reflective structures on the lower surface of the transparent substrate, an optical sheet as described above can be produced.

The present invention has been described above by way of examples, and is not intended to limit the scope of the claims. The scope of patent protection is subject to the attached application The scope of patents and their equivalents are determined. Modifications or modifications made by those skilled in the art, without departing from the spirit or scope of the invention, are equivalent to the equivalents or modifications made in the spirit of the invention and should be included in the following claims. Inside.

<知知>

1‧‧‧Direct type backlight module

11‧‧‧Frame

12‧‧‧Light source device

13‧‧‧shade

14‧‧‧Fresnel lens

14A‧‧‧Glossy

<present invention>

2‧‧‧Backlight module

21‧‧‧Frame

22‧‧‧Light source device

24‧‧‧ optical sheet

241‧‧‧ Ontology

241A‧‧‧Glossy

241B‧‧‧Into the glossy surface

242‧‧‧Fresnel lens unit

2421‧‧‧Fresnel lens

2421A‧‧‧ first endpoint

2421B‧‧‧second end

2421C‧‧‧First refractive surface

2421D, 2421D'‧‧‧second refractive surface

243‧‧‧Reflective structure

25‧‧‧Optical diaphragm

θ 1‧‧‧ first angle

θ 2‧‧‧second angle

L1, L2, L3‧‧‧ rays

342‧‧‧Fresnel lens unit

3421‧‧‧Fresnel lens

3421A‧‧‧First Endpoint

3421B‧‧‧second endpoint

FIG. 1 is a schematic diagram of a direct type backlight module of the Republic of China Patent No. I264596.

2 is a schematic view showing an embodiment of an optical sheet of the present invention.

3A is a schematic view showing a first embodiment of a Fresnel lens unit of an optical sheet of the present invention.

FIG. 3B is a schematic view showing a second embodiment of the Fresnel lens unit of the optical sheet of the present invention.

FIG. 4 is a schematic view showing an embodiment of a backlight module using an optical sheet according to the present invention.

FIG. 5 is a graph showing the optical performance test of the optical sheet of the present invention under different T/P values.

FIG. 6 is a graph showing the optical performance test of the optical sheet of the present invention under different aperture ratio conditions.

FIG. 7 is a comparison diagram of optical performance tests of an optical sheet using a Fresnel lens and a conventional brightness enhancement film according to the present invention.

FIG. 8 is a graph showing the optical performance test of the optical sheet of the present invention under different reflective structure thickness conditions.

FIG. 9 is a comparison diagram of optical performance tests of the optical sheet of the present invention and a conventional brightness enhancing film in a vertical viewing angle.

FIG. 10 is a comparison diagram of optical performance tests of the optical sheet of the present invention and a conventional brightness enhancing film in a horizontal viewing angle.

24‧‧‧ optical sheet

241‧‧‧ Ontology

241A‧‧‧Glossy

241B‧‧‧Into the glossy surface

242‧‧‧Fresnel lens unit

2421‧‧‧Fresnel lens

243‧‧‧Reflective structure

Claims (17)

An optical sheet for receiving incident light projected by a light source, the optical sheet comprising: a body comprising a corresponding one of the light incident surface and a light exiting surface, the light incident surface receiving the incident light Light, and at an incident angle with the incident light, the body has at least a refractive index ni, i is a positive integer; a plurality of reflective structures are located in the body, and the distance between two adjacent reflective structures is horizontal a spacing W of the light incident surface, each reflecting structure has a thickness t perpendicular to the light incident surface along a direction in which the incident light is incident; a plurality of Fresnel lens units, each Fresnel lens unit Located on the illuminating surface, and the Fresnel lens unit defines a width P along the direction of the illuminating surface, and each Fresnel lens unit corresponds to the spacing; when the formula is satisfied: When j≧1, the incident light passes through the pitch, and the incident angle is adjusted by the thickness t, and the optical path of the incident light is converged by the plurality of Fresnel lens units. The optical sheet of the first aspect of the invention, wherein the material of the body is a polyethylene terephthalate (PET), a polycarbonate (Polycarbonate, PC), a triacetate (Tri- Acetyl Cellulose, TAC), Polymethylmethacrylate (PMMA), Methylmethacrylate styrene, Polystyrene (PS), or a cyclic olefin copolymer (Cyclic Olefin Copolymer, COC). The optical sheet of claim 1, wherein each of the Fresnel lens units further comprises a plurality of Fresnel lenses, and each Fresnel lens has a first end point and a first a second end point, the Fresnel lens body and the other Fresnel lens body are respectively located on two sides of the second end point, and the plurality of first end points are substantially aligned to form a straight line, and the second end point and the straight line There is a height apart, the heights of the two adjacent second end points are unequal, and the heights of the first end points of the two adjacent Fresnel lens units are equal. The optical sheet of claim 1, wherein the ratio of the pitch W to the width P is in the range of 0.2 to 0.5. The optical panel of claim 1, wherein the light-emitting surface is at a distance T from the light-incident surface, and the ratio of the distance T to the width P is in a range of 0.8 to 1.2. The optical sheet of claim 1, wherein the reflective structures are made of titanium dioxide, cerium oxide or magnesium monoxide. A method for manufacturing a cured optical sheet according to claim 1, comprising the steps of: providing a transparent substrate having an upper surface and a lower surface, a curing adhesive, a mold, and a plurality of reflective structures; coating the Curing the glue on the upper surface; applying a plurality of patterns on the surface of the mold to emboss the cured glue to produce a plurality of corresponding Fresnel lens units; and hardening the plurality of Fresnel lenses on the cured glue a unit; and combining the plurality of reflective structures on the lower surface. The method for manufacturing a cured optical sheet according to claim 7, wherein the transparent substrate is only a polyethylene terephthalate (PET), a polycarbonate (Polycarbonate, PC), Tri-acetyl Cellulose (TAC), Polymethylmethacrylate (PMMA), Methylmethacrylate styrene, Polystyrene, PS) or a material of a Cyclic Olefin Copolymer (COC). The method for manufacturing a cured optical sheet according to claim 7, wherein the cured adhesive is a UV curable resin or a thermo-plastic resin. The method for manufacturing a cured optical sheet according to claim 7, wherein the mold is a roller or a flat mold. The method for manufacturing a cured optical sheet according to claim 7, wherein the bonding step of the plurality of reflective structures is a paste method or a screen printing method. An extrusion molding manufacturing method for an optical sheet according to claim 1, comprising the steps of: providing a transparent substrate having an upper surface and a lower surface, a mold, and a plurality of reflective structures; Having a plurality of patterns for embossing the transparent substrate to produce a plurality of corresponding Fresnel lens units on the upper surface of the transparent substrate; The plurality of reflective structures are bonded to the lower surface of the transparent substrate. The method for manufacturing an extrusion molding of an optical sheet according to claim 12, wherein the transparent substrate is only a polyethylene terephthalate (PET), a polycarbonate (Polycarbonate, PC). , Tri-acetyl Cellulose (TAC), Polymethylmethacrylate (PMMA), Methylmethacrylate styrene, Polystyrene , PS) or a material of Cyclic Olefin Copolymer (COC). The method for manufacturing an extrusion molding of an optical sheet according to claim 12, wherein the mold is a roller or a flat mold. The method for manufacturing an extrusion molding of an optical sheet according to claim 12, wherein the bonding step of the plurality of reflective structures is a bonding method or a screen printing method. A backlight module includes: a plurality of light source devices for generating incident light; and an optical thin plate for receiving the incident light projected by the plurality of light source devices, the optical thin plate comprising: a body, the body comprising Corresponding to one of the light incident surface and the light exiting surface, the light incident surface receives the incident light and has an incident angle with the incident light, the body has at least a refractive index ni, i is a positive integer; a reflective structure is disposed in the body, and two adjacent reflective structures are spaced apart from each other by a spacing W horizontal to the light incident surface, and each of the reflective structures has a direction perpendicular to the light incident surface along a direction in which the incident light is incident. a thickness of t; a plurality of Fresnel lens units, each Fresnel lens unit is located on the light-emitting surface, and the Fresnel lens unit defines a width P along the direction of the light-emitting surface, each of The Fresnel lens unit corresponds to the spacing; when the formula is satisfied: , j≧1, the incident light passes through the spacing, and the incident angle is adjusted by the thickness t, and the optical path of the incident light is converged by the plurality of Fresnel lens units; and an optical film The optical sheet is disposed on the other side of the optical sheet with respect to the light source device, and the optical film corrects the optical path of the incident light. The backlight module of claim 16, wherein the light source device is a cold cathode fluorescent lamp (CCFL), a light emitting diode (LED), a planar light source (FFL), and an external electrode. Light tube (EEFL) or a hot cathode fluorescent tube (HCFL).