CN116381985A - Optical film and method for manufacturing the same - Google Patents

Abstract

An optical film comprises a first optical layer and a second optical layer, wherein the first optical layer comprises a plurality of concave microstructures, the concave microstructures are arranged adjacently to each other, and a plurality of ridge lines are formed at the connection positions of the concave microstructures. The concave microstructure comprises a curved surface bottom point, a plurality of first side surfaces and a plurality of first adjacent curved surfaces, wherein the first adjacent curved surfaces meet at the curved surface bottom point, and the side surfaces are positioned between the two first adjacent curved surfaces. Wherein the ridges intersect each other to form a plurality of quadrangles or triangles. The invention has the advantage of providing better light diffusion effect.

Description

Optical film and method for manufacturing the same

Technical Field

An optical film, in particular to an optical film applied to a backlight module.

Background

In a backlight module of a liquid crystal screen, an optical film having a microstructure on a surface is almost a necessary component. The optical film can reflect or refract light by utilizing the physical phenomena of the microstructures, thereby achieving the effect of light diffusion. Therefore, the light of the light-emitting component at the bottom layer can be more uniform, so that the quality of a display picture of the liquid crystal screen is improved.

With the technical progress, a Light Emitting Diode (LED) light source in a backlight module is gradually replaced by a sub-millimeter light emitting diode (Mini LED) or a Micro light emitting diode (Micro LED), and the light emitting area of the sub-millimeter light emitting diode (Mini LED) is small, so that the light of the sub-millimeter light emitting diode (Mini LED) cannot be effectively diffused by a traditional optical film, and the quality of a display picture of a liquid crystal screen is affected. The conventional solution is to use more optical films to obtain the ideal diffusion effect, but this increases the thickness of the backlight module, which is not in line with the market trend.

Therefore, it is worth considering by those skilled in the art how to solve the above problems.

Disclosure of Invention

In view of the above, the present invention provides an optical film having a concave microstructure with a curved surface, which can provide a better light diffusion effect, can be used for small sub-millimeter light emitting diodes (Mini LEDs) or Micro light emitting diodes (Micro LEDs), and can maintain the thickness of a backlight module. The specific technical means are as follows:

an optical film comprises a first optical layer and a second optical layer, wherein the first optical layer comprises a plurality of concave microstructures, the concave microstructures are arranged adjacently to each other, and a plurality of ridge lines are formed at the connection positions of the concave microstructures. The concave microstructure comprises a curved surface bottom point, a plurality of first side surfaces and a plurality of first adjacent curved surfaces, wherein the first adjacent curved surfaces meet at the curved surface bottom point, and the side surfaces are positioned between the two first adjacent curved surfaces. Wherein the ridges intersect each other to form a plurality of quadrangles or triangles.

The optical film further comprises a substrate layer and a second optical layer, wherein the first optical layer is arranged on one surface of the substrate layer, and the second optical layer is arranged on the other surface of the substrate layer.

In the optical film, the second optical layer includes a plurality of first refractive structures, and the refractive index of the first refractive structures is different from the refractive index of the substrate layer.

In the above optical film, the second optical layer further includes a plurality of second refractive structures, the second refractive structures and the first refractive structures are mutually matched, and the refractive index of the first refractive structure is different from the refractive index of the second refractive structure.

In the above optical film, the refractive index of the first refractive structure and the refractive index of the second refractive structure differ by at least 0.1.

In the above optical film, the geometry of the second optical layer is the same as the geometry of the first optical layer.

In the above optical film, when a light beam is incident on the first side of the concave microstructure, the first side totally reflects the light beam if the incident angle of the light beam is greater than a critical angle.

The invention also provides a manufacturing method of the optical film, which comprises the following steps. First, in the optical film, when a light is incident on the first side of the concave microstructure, the first side totally reflects the light if the incident angle of the light is greater than a critical angle. A mold substrate is provided. Then, a diamond cutter is used for carving the surface of the mould base material to form a plurality of cone structures. Then, sand blasting is carried out on the conical structure, so that the vertex of the conical structure forms a curved surface vertex, the edge of the conical structure forms a plurality of second adjacent curved surfaces, and the conical structure comprises a plurality of second side surfaces. And then, extruding the optical layer by using the conical structure of the die base material to form a plurality of concave microstructures on the optical layer. And curing the optical layer to form an optical film.

In the above-described method for manufacturing an optical film, in step S40, the taper structure is a quadrangular pyramid.

In the above-described method for producing an optical film, in step S40, the taper structure is a triangular pyramid.

In the above-described method for producing an optical film, in step S30, the mold base is a roller.

In the above-described method for producing an optical film, in step S60, both surfaces of the optical film base material are pressed.

The invention also provides an optical film manufactured by the manufacturing method of the optical film.

In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below. It should be noted that the components in the drawings are schematic and are not drawn to actual scale.

Drawings

Fig. 1 shows a microscopic image of an optical film 100 according to the present invention.

Fig. 2 is a side cross-sectional view of the optical film 100 of the present invention.

Fig. 3 is a schematic diagram of a concave microstructure 121.

Fig. 4 is a schematic diagram of a concave microstructure 121' according to another embodiment.

Fig. 5 is a schematic horizontal cross-section of a recessed microstructure.

Fig. 6 shows an optical film 200 according to a second embodiment.

Fig. 7 shows an optical film 300 according to a third embodiment.

Fig. 8 shows an optical film 400 according to a fourth embodiment.

Fig. 9 and fig. 10 to 16 illustrate a method for manufacturing the optical film 100 according to the present invention.

Fig. 17 is a schematic view of the cone-shaped structure 11.

Fig. 18 is a schematic view of the cone structure 11 after sandblasting.

Fig. 19 is a light ray simulation diagram of the first embodiment.

Fig. 20 is a light ray simulation diagram of the second embodiment.

Detailed Description

In order to describe the technical content, constructional features, achieved objects and effects of the technical solution in detail, the following description is made in connection with the specific embodiments in conjunction with the accompanying drawings.

Referring to fig. 1 and 2, fig. 1 shows an electron microscope image (SEM) of an optical film 100 according to the present invention, and fig. 2 shows a side cross-sectional view of the optical film 100 according to the present invention. Wherein fig. 2 is a cross-sectional view of line A-A of fig. 1. The optical film 100 of the present invention includes a substrate layer 110 and a first optical layer 120. The first optical layer 120 is disposed on the substrate layer 110, and the first optical layer 120 further includes a plurality of concave microstructures 121. As can be seen from fig. 1 and 2, the concave microstructure 121 is concave from the surface of the optical film 100, and is concave in a bowl-like shape in a vertical section (e.g., a section of A-A line), and the curved surface of the concave microstructure 121 provides an effect equivalent to a concave lens, which can effectively enhance the diffusion effect of light. In addition, the concave microstructures 121 are disposed on the first optical layer 120 in the adjacent arrangement, and a plurality of ridges 130 are formed at the connection position of each concave microstructure 121. In addition, in the preferred embodiment, the light incident surface 111 of the substrate layer 110 may be a rough microstructure surface, so as to further improve the light diffusion effect. Specifically, the rough surface of the light incident surface 111 has an optical haze of 5% to 70%, and the reason is that the light diffusion effect is poor when the optical haze is less than 5%, and the light transmittance is insufficient when the optical haze is more than 70%.

Referring to fig. 3, fig. 3 is a schematic diagram of a concave microstructure 121. It can be seen that the concave microstructure 121 includes a curved bottom 1212, a plurality of first sides 1213, a plurality of adjacent curved surfaces 1214, and an opening 1211, wherein the first sides 1213 are located between the two adjacent curved surfaces 1214. Further, the first side 1213 is relatively close to a plane with respect to the adjacent curved surface 1214. When light enters the optical film 100 from the light incident surface 111 and enters the first side 1213 of the concave microstructure 121, if the incident angle is greater than the critical angle (i.e. the light is far away from the normal), the first side 1213 has a function of total internal reflection, and reflects the light toward the inner side of the optical film 100.

Referring to fig. 5, fig. 5 is a schematic horizontal cross-sectional view of a concave microstructure. In fig. 5, horizontal sections 121a to 121e at different depth positions in the concave microstructure 121 are drawn, and the horizontal section of the concave microstructure 121 presents a sharp polygon such as a quadrangle horizontal section 121a when the surface of the optical film 100 is formed, while the section of the concave microstructure 121 gradually approaches a circular shape and gradually reduces in area as the horizontal section 121b to 121d gradually changes from a rounded quadrangle to a circular shape along the direction toward the center of the optical film 100. Up to the location of the curved bottom point 1212, it approaches a dot, like the horizontal section 121e, forming a concave shape resembling a bowl.

Referring back to fig. 3 and 4, the opening 1211 forms a ridge 130 with the other adjacent recessed microstructures 121. In the embodiment of fig. 3, the opening 1211 is square. Referring to fig. 4, fig. 4 is a schematic diagram of a concave microstructure 121' according to another embodiment. In the embodiment of fig. 4, the openings 1211 'of the recessed microstructures 121' are triangular.

Referring to fig. 6, fig. 6 shows an optical film 100 according to a second embodiment. In the embodiment of fig. 5, the optical film 200 includes a substrate layer 110, a first optical layer 120 and a second optical layer 210, and the first optical layer 120 includes a plurality of concave microstructures 121 thereon, and the features are similar to those of fig. 1 to 4 and are not repeated here. The second embodiment is characterized in that the optical film 200 further includes a second optical layer 210 disposed on the other surface of the substrate layer 110 opposite to the first optical layer 120. The geometry of the second optical layer 210 is the same as the geometry of the first optical layer 110, i.e. the second optical layer 210 also comprises a plurality of recessed microstructures 221, and the recessed microstructures 221 have the same shape as the recessed microstructures 121 of the first optical layer 120. That is, the concave microstructures 121 and 221 are disposed on both the light emitting surface and the light entering surface of the optical film 100, so as to further improve the light diffusion effect.

Referring to fig. 7, fig. 7 shows an optical film 300 according to a third embodiment. In the embodiment of fig. 6, the optical film 300 includes a substrate layer 110 and a first optical layer 120, and the first optical layer 120 includes a plurality of concave microstructures 121 thereon, and the features are similar to those of fig. 5 and are not repeated here. The third embodiment is characterized in that a second optical layer 310 is further provided on the other surface of the base layer 110. The second optical layer 310 is disposed on the light incident surface of the optical film 300, i.e. on the other surface of the substrate layer 110 opposite to the first optical layer 120. And, the second optical layer 310 further includes a plurality of first refractive layers 311, and the refractive index of the first refractive layers 311 is different from that of the base layer 110. In this way, after the light enters the optical film 300, the light is refracted multiple times by the first refraction layer 311, the substrate layer 110 and the first optical layer 120, so as to improve the light diffusion effect. In addition, the first refraction layer 311 further includes a plurality of tapered microstructures, which may be formed by protrusions or depressions on the first refraction layer 311.

Referring to fig. 8, fig. 8 shows an optical film 400 according to a fourth embodiment. The optical film 400 includes a substrate layer 110, a first optical layer 120, and a second optical layer 410. In the fourth embodiment, the second optical layer 410 includes a first refractive layer 311 and a second refractive layer 412, and the second refractive layer 412 and the first refractive layer 311 are mutually matched. Namely, the first refraction layer 311 and the second refraction layer 412 have corresponding shapes and can be bonded to form a refraction surface. The first refractive layer 311 and the second refractive layer 412 are bonded to each other to form a plane on the light incident surface.

And the refractive index of the first refractive layer 311 is different from that of the second refractive layer 412. In detail, the difference between the refractive index of the first refractive layer 311 and the refractive index of the second refractive layer 412 is at least 0.1. The first refraction layer 311 and the second refraction layer 412 are disposed on the light incident surface of the optical film 400, so that after the light enters the optical film 400, the light is refracted and reflected by the second refraction layer 412, the first refraction layer 311, the substrate layer 110 and the first optical layer 120 for multiple times, thereby further improving the light diffusion effect. The method for producing the optical film 100 of the present invention is described below. In a preferred embodiment, the light incident surface of the second refraction layer 412 has a rough surface, so as to further increase the light diffusion effect, the optical haze of the surface roughness is 5% -70%, less than 5% of the light diffusion effect is too poor, and more than 70% of the light transmittance is low.

Referring to fig. 9 and fig. 10 to 16, fig. 9 and fig. 10 to 16 illustrate a method for manufacturing an optical film 100 according to the present invention. First, as shown in fig. 10, step S10 is performed to provide an optical film substrate 102, where the optical film substrate 102 is, for example, glass, polymethyl acrylate (PMMA), polyethylene terephthalate (PET), or Polycarbonate (PC). Next, as shown in fig. 11, step S20 is performed to coat an optical layer 101 on one surface of the optical film substrate 102. The optical layer 101 is, for example, an Ultraviolet (UV) optical resin.

Then, referring to fig. 12, step S30 is performed to provide a mold substrate 10. The mold substrate 10 shown in fig. 12 is a portion of a cylindrical roller surface. In another embodiment, the mold base 10 may also be a planar sheet.

Next, as shown in fig. 13, step S40 is performed, and the surface of the mold base material 10 is engraved using the cutter 20, thereby forming a plurality of taper structures 11. Specifically, a diamond cutter is used as the cutter 20, and the surface of the mold base 10 is engraved in parallel in the X direction and then engraved in parallel in the Y direction, thereby forming a plurality of tapered structures 11 with four corners and bottom surfaces. In other embodiments, the surface of the mold substrate 10 is engraved in parallel in three directions with an included angle of 60 ° to form a plurality of triangular bottom cone structures 11, and the processing method is not limited thereto.

Then, as shown in fig. 14, step S50 is performed to blast the mold base 10 so that the apex of the tapered structure 11 forms a rounded apex. That is, the mold base material 10 is put into a sand blasting apparatus to perform sand blasting, and the sharp vertex of the tapered structure 11 is polished to a curved vertex by impact polishing of sand grains. Notably, the slits 12 remain sharp in shape because the sand used for blasting cannot enter the slits 12 between each cone-shaped structure 11.

Referring to fig. 17, fig. 17 is a schematic view of a tapered structure 11. The cone-shaped structure 11 has a sharp quadrangular pyramid shape before sand blasting, and includes a bottom surface 2211, an apex 2212, a plurality of second side surfaces 2213, and a plurality of edges 2215.

Referring to fig. 18, fig. 18 is a schematic view of the conical structure 11' after sandblasting. The original cone-shaped structure 11 is sandblasted to form a dome shape, so that a curved peak 2212', a plurality of second side surfaces 2213', and a plurality of second adjacent curved surfaces 2214 are formed, wherein the second adjacent curved surfaces 2214 are located between the two second side surfaces 2213. Specifically, the second adjacent curved surface 2214 is passivated by the edge 2215 of the conical structure 11 through the impact of sand grains to form a curved surface shape. Whereas the edge 2215 adjacent to the bottom surface 2211 maintains a sharp shape because the sand of the blasting cannot touch. In addition, the portion of the second side 2213 adjacent to the bottom surface 2211 remains a complete plane, again because the grit of the grit blast cannot touch.

Next, referring back to fig. 15, step S60 is performed to mold the optical layer 101 using the mold base material 10 after sandblasting, and to form a concave microstructure on the optical layer 101. Specifically, the optical layer 101 is roll-formed by using a mold base 10 having a roller.

Next, referring to fig. 16, step S70 is performed to cure the optical film substrate 101. Specifically, the optical film substrate 101 is cured by applying a corresponding method, such as irradiation of ultraviolet light 21 or heating, according to the material selected for the optical film substrate 101. In practice, a photo-curable material such as "Ultraviolet (UV) curable resin" is used for ultraviolet curing, drying, and adhesion (UV curing). Thus, the optical film 100 having the depressed microstructure 121 is obtained. The slits 12 between each of the tapered structures 11 on the mold substrate 10 form ridges 130 between the recessed microstructures 121.

Referring to fig. 18 and 3, since the concave microstructure 121 is formed by extruding the tapered structure 11 'on the mold substrate 10, the concave microstructure 121 has a shape corresponding to the tapered structure 11'. For example, the curved apex 2212' of the tapered structure 11' forms the curved bottom 1212 of the concave microstructure 121, and the opening 1211 of the concave microstructure 121 corresponds to the bottom 2211 of the tapered structure 11 '. A portion of the second side 2213 of the tapered structure 11' adjacent to the bottom surface 2211 forms a ridge 130 around the periphery of the concave microstructure 121.

Referring back to fig. 9, in one embodiment, the steps S10 to S70 are implemented through a Roll-to-Roll (Roll to Roll) process, that is, the optical film substrate 101 is pressed by a roller as the mold substrate 10 in a rolling manner, the concave microstructures 121 are formed on the optical film substrate 101, and the optical film substrate 101 is cured by ultraviolet irradiation, but the present invention is not limited to the ultraviolet curing, drying, and adhesion (UV curing) and the photo-curing materials used therein. The following describes the results of light simulation of the optical film of the present invention.

Referring to fig. 19, fig. 19 is a light ray simulation diagram of the first embodiment. In the embodiment of fig. 17, the simulation is performed using the aforementioned optical film 100 (see fig. 2), and the light path is represented by a vertical line from below to above. As can be seen from fig. 17, when light passes through the optical film 100 and leaves the optical film 100 from the upper surface, the light is refracted by the first optical layer, and an effect corresponding to a concave lens is generated, so that the light is scattered, and a diffusion effect is achieved.

Referring to fig. 20, fig. 20 is a light ray simulation diagram of a second embodiment. In the embodiment of fig. 18, the simulation is performed using the aforementioned optical film 300 (see fig. 7), and the light path is represented by a vertical line from below to above. As can be seen from fig. 18, when the light passes through the optical film 300 and leaves the optical film 100 from the upper surface, the light is refracted multiple times by the second optical layer and the first optical layer, so that the light is further scattered, and a more diffuse effect is achieved.

The optical film 100 of the present invention has a curved concave microstructure, and can provide an optical refraction effect equivalent to that of a concave lens, and can provide a more effective light diffusion effect. Therefore, a better diffusion effect can be achieved by using fewer optical films, so that excessive optical films can be prevented from being stacked, and the thickness of the backlight module can be further reduced.

The above embodiments are for convenience of description only, and modifications may be made by those skilled in the art without departing from the scope of the invention as claimed.

Claims (14)

1. An optical film, comprising:

the first optical layer comprises a plurality of concave microstructures which are arranged adjacently to each other, and a plurality of ridge lines are formed at the connection positions of the concave microstructures;

the concave microstructure comprises a curved surface bottom point, a plurality of first side surfaces and a plurality of first adjacent curved surfaces, wherein the first adjacent curved surfaces meet at the curved surface bottom point, and the side surfaces are positioned between the two first adjacent curved surfaces;

wherein the ridges intersect each other to form a plurality of quadrangles or triangles.

2. The optical film of claim 1, further comprising a substrate layer and a second optical layer, the first optical layer disposed on one surface of the substrate layer and the second optical layer disposed on the other surface of the substrate layer.

3. The optical film of claim 2, wherein the second optical layer comprises a plurality of first refractive structures having a refractive index different from the refractive index of the base layer.

4. The optical film of claim 3, wherein the second optical layer further comprises a plurality of second refractive structures, the second refractive structures and the first refractive structures being compatible with each other, and the refractive index of the first refractive structures being different from the refractive index of the second refractive structures.

5. The optical film of claim 4, wherein the refractive index of the first refractive structure differs from the refractive index of the second refractive structure by at least 0.1.

6. The optical film of claim 2, wherein the geometry of the second optical layer is the same as the geometry of the first optical layer.

7. The optical film of claim 1, wherein when a light is incident on the first side of the concave microstructure, the first side totally reflects the light if the incident angle of the light is greater than a critical angle.

8. A method of manufacturing an optical film, comprising:

s10: providing an optical film substrate;

s20: coating an optical layer on the optical film substrate;

s30: providing a mold substrate;

s40: engraving the surface of the mold substrate by using a cutter to form a plurality of cone structures;

s50: performing sand blasting on the conical structure to enable the vertex of the conical structure to form a curved surface vertex, and enabling the edge of the conical structure to form a plurality of second adjacent curved surfaces and comprise a plurality of second side surfaces;

s60: extruding the optical layer using the tapered structure of the mold substrate to form a plurality of recessed microstructures on the optical layer; a kind of electronic device with high-pressure air-conditioning system

S70: the optical layer is cured to form an optical film.

9. The method of manufacturing an optical film according to claim 8, wherein in step S40, the taper structure is a quadrangular pyramid.

10. The method of manufacturing an optical film according to claim 8, wherein in step S40, the tapered structure is a triangular pyramid.

11. The method of manufacturing an optical film according to claim 8, wherein in step S30, the mold base is a roller.

12. The method of manufacturing an optical film according to claim 8, wherein in step S60, both sides of the optical film substrate are pressed.

13. The method of manufacturing an optical film according to claim 8, wherein the optical layer is an ultraviolet curable resin.

14. An optical film produced by the method for producing an optical film according to any one of claims 8 to 12.

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