Viewing angle enlargement film and preparation method thereof, and display device

Abstract

The present invention relates to a viewing angle expansion film and a preparation method thereof, and a display device. The viewing angle expansion film of the present invention cooperates with a first film layer with a low refractive index and a second film layer with a high refractive index. When light irradiates the first film layer and the second film layer, the extension direction of the first protrusion is parallel to the first direction; the light is diffused in the second direction; the extension direction of the second protrusion is parallel to the second direction; the light is diffused in the first direction; and the viewing angle expansion film can diffuse in the first direction and the second direction at the same time. When the viewing angle expansion film is applied to a display device, the viewing angle of the display device in the first direction and the second direction can be expanded at the same time.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a viewing angle expansion film and a preparation method thereof, and a display device. Background Art

[0002] Liquid Crystal Display (LCD) uses liquid crystal material as its basic component. Liquid crystal material is filled between two parallel plates. Voltage is used to change the arrangement of molecules inside the liquid crystal material to achieve the purpose of shading and transmitting light to display images of varying depths and staggered arrangements. Moreover, as long as a filter layer of three primary colors is added between the two flat plates, color images can be displayed.

[0003] At present, vertical alignment (VA) liquid crystal displays have the advantages of high contrast, bright colors and fast response time, and are widely used in consumer electronic products such as televisions. However, the viewing angle (viewing angle) of VA liquid crystal displays is not as good as that of In-Plane Switching (IPS) liquid crystal displays.

[0004] Although there are technologies available to improve the viewing angle of VA-type liquid crystal displays, such as pixel diversification to improve the viewing angle, the viewing angle improvement effect is limited and can only expand the left and right viewing angles of the liquid crystal display, resulting in failure to meet some special application scenarios. For example, shopping malls not only require a larger left and right viewing angle, but also a larger top and bottom viewing angle, so that the content of the liquid crystal display can be clearly seen in all directions. Summary of the invention

[0005] The purpose of the present invention is to provide a viewing angle expansion film and its preparation method, and a display device, which can solve the problems that the prior art can only expand the left and right viewing angles of liquid crystal displays, but cannot meet the needs of expanding both the left and right viewing angles and the up and down viewing angles.

[0006] In order to solve the above problems, the present invention provides a viewing angle expansion film, which includes: a first film layer, which includes a flat layer and a plurality of first protrusions and a plurality of second protrusions arranged on the flat layer, the plurality of first protrusions are spaced apart from each other along a first direction and a second direction perpendicular to the first direction and are arranged in an array on the flat layer, and the extension directions of the first protrusions are all parallel to the first direction; a plurality of second protrusions are spaced apart from each other along the first direction and the second direction and are arranged in an array on the flat layer, and are spaced apart from the first protrusions, and the extension directions of the second protrusions are all parallel to the second direction; a second film layer, which is arranged on the first film layer and fills the gap between adjacent first protrusions and the second protrusions, the gap between two adjacent first protrusions, and the gap between two adjacent second protrusions, and the refractive index of the second film layer is greater than the refractive index of the first film layer.

[0007] Further, in the first direction and / or the second direction, the first protrusions and the second protrusions are arranged alternately.

[0008] Furthermore, the first film layer and / or the second film layer further comprises a plurality of scattering particles, and the content of the scattering particles is in a range of 1%-30%.

[0009] Furthermore, the refractive index of the material of the first film layer is in the range of 1.3-1.6; the refractive index of the material of the second film layer is in the range of 1.5-1.9.

[0010] Furthermore, each of the first protrusions includes a first inclined plane and a second inclined plane, and a first intersection line between the first inclined plane and the flat layer and a second intersection line between the second inclined plane and the flat layer are both parallel to the first direction; each of the second protrusions includes a third inclined plane and a fourth inclined plane, and a third intersection line between the third inclined plane and the flat layer and a fourth intersection line between the fourth inclined plane and the flat layer are both parallel to the second direction.

[0011] Furthermore, the first protrusion and the second protrusion have the same shape and size, and the shape of the first protrusion is an isosceles trapezoidal prism; the edge length of the first protrusion ranges from 2 microns to 60 microns, and the height of the first protrusion ranges from 4 microns to 20 microns; the angle between the first inclined surface of the first protrusion and the flat layer is greater than 0° and less than 80°, and the width of the lower base length of the cross section of the first protrusion perpendicular to the edge length ranges from 5 microns to 20 microns.

[0012] Furthermore, on a cross section parallel to the second direction, the distance between two adjacent second protrusions and the sum of the edge lengths of the second protrusions range from 20 microns to 100 microns; on a cross section parallel to the first direction, the distance between two adjacent first protrusions and the sum of the edge lengths of the first protrusions range from 20 microns to 80 microns, and the distance between two adjacent second protrusions and the sum of the bottom lengths of the cross section of the second protrusion perpendicular to its edge length range from 20 microns to 80 microns.

[0013] In order to solve the above problems, the present invention also provides a method for preparing a viewing angle expansion film, which includes the following steps: providing a substrate; arranging a first film layer on the substrate; the first film layer includes a flat layer and a plurality of first protrusions and a plurality of second protrusions arranged on the flat layer, the plurality of first protrusions are spaced apart from each other along a first direction and a second direction perpendicular to the first direction and are arranged in an array on the flat layer, and the extension directions of the first protrusions are all parallel to the first direction; the plurality of second protrusions are spaced apart from each other along the first direction and the second direction and are arranged in an array on the flat layer, and are spaced apart from the first protrusions, and the extension directions of the second protrusions are all parallel to the second direction; a second film layer is arranged on the first film layer, the second film layer fills the gap between adjacent first protrusions and the second protrusions, the gap between two adjacent first protrusions, and the gap between two adjacent second protrusions, and the refractive index of the second film layer is greater than the refractive index of the first film layer.

[0014] Furthermore, the step of setting a first film layer on the substrate includes: setting a flat layer on the light-emitting surface of the substrate; coating a first resin on the surface of the flat layer away from the substrate, and obtaining a plurality of first protrusions and a plurality of second protrusions after exposure, development and patterning.

[0015] In order to solve the above problems, the present invention further provides a display device, which includes the viewing angle expansion film of the present invention.

[0016] The advantages of the present invention are: the viewing angle expansion film of the present invention cooperates with the first film layer with a low refractive index and the second film layer with a high refractive index. When light irradiates the first film layer and the second film layer, the extension direction of the first protrusion is parallel to the first direction; the light is diffused in the second direction; the extension direction of the second protrusion is parallel to the second direction; the light is diffused in the first direction; and the viewing angle expansion film can diffuse in the first direction and the second direction at the same time. When the viewing angle expansion film is applied to a display device, the viewing angle of the display device in the first direction and the second direction can be expanded at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 is a schematic structural diagram of a display device according to Embodiment 1 of the present invention;

[0019] Figure 2 is a schematic structural diagram of a viewing angle expansion film according to Example 1 of the present invention;

[0020] Figure 3 yes Figure 2 Exploded view of the perspective-enlarged film;

[0021] Figure 4 is a schematic structural diagram of the first film layer of the viewing angle expansion film of Example 1 of the present invention;

[0022] Figure 5 yes Figure 2 AA cross-section diagram;

[0023] Figure 6 yes Figure 4 BB cross-section diagram;

[0024] Figure 7 yes Figure 4 CC cross-section diagram;

[0025] Figure 8 is a diagram of the steps for preparing the viewing angle expansion film of Example 1 of the present invention;

[0026] Fig. 9 Schematic diagram of the structure of the first film layer of the viewing angle expansion film of Example 2 of the present invention.

[0027] Description of reference numerals:

[0028] 100. Display device;

[0029] 1. Backlight module; 2. First polarizer;

[0030] 3. Array substrate; 4. Liquid crystal layer;

[0031] 5. Color film substrate; 6. Second polarizer;

[0032] 7. Viewing angle expansion film;

[0033] 71. a first film layer; 72. a second film layer;

[0034] 73. substrate;

[0035] 711, flat layer; 712, first protrusion;

[0036] 713, second protrusion;

[0037] 7121. The first inclined plane; 7122. The second inclined plane;

[0038] 7131, the third inclined plane; 7132, the fourth inclined plane. DETAILED DESCRIPTION

[0039] The preferred embodiments of the present invention are described in detail below in conjunction with the drawings in the specification, so as to fully introduce the technical content of the present invention to those skilled in the art, to illustrate that the present invention can be implemented, to make the technical content disclosed in the present invention clearer, and to make it easier for those skilled in the art to understand how to implement the present invention. However, the present invention can be embodied through many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text, and the description of the embodiments below is not intended to limit the scope of the present invention.

[0040] The directional terms mentioned in the present invention, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "side", etc., are only directions in the drawings. The directional terms used in this article are used to explain and illustrate the present invention, rather than to limit the scope of protection of the present invention.

[0041] In the drawings, components with the same structure are represented by the same numerical numerals, and components with similar structures or functions are represented by similar numerical numerals. In addition, for ease of understanding and description, the size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component.

[0042] Example 1

[0043] like Figure 1 As shown, this embodiment provides a display device 100. The display device 100 includes: a backlight module 1, a first polarizer 2, an array substrate 3, a liquid crystal layer 4, a color filter substrate 5, a second polarizer 6 and a viewing angle expansion film 7.

[0044] The backlight module 1 has a light emitting side 11. The backlight module 1 includes: a light source (not shown), an optical film (not shown), a reflective film (not shown), etc. The light source can be a direct light source or an edge light source.

[0045] The first polarizer 2 is arranged on the light-emitting side 11 of the backlight module 1. The basic structure of the first polarizer 2 includes: PVA (polyvinyl alcohol) and TAC (triacetyl cellulose) arranged on both sides of the PVA. The PVA layer plays a polarizing role, but PVA is very easy to hydrolyze. In order to protect the physical properties of the polarizing film, a layer of (TAC) film with high light transmittance, good water resistance and certain mechanical strength is compounded on both sides of the PVA for protection.

[0046] The array substrate 3 is disposed on a side of the first polarizer 2 away from the backlight module 1. The array substrate 3 includes: a thin film transistor device (not shown), a first alignment film (not shown) and other film layer structures.

[0047] The color filter substrate 5 is arranged opposite to the array substrate 3 and is located on a side of the array substrate 3 away from the backlight module 1. The color filter substrate 5 includes: a second alignment film (not shown), a color filter (not shown), a black matrix (not shown) and other film structures.

[0048] The liquid crystal layer 4 is disposed between the array substrate 3 and the color filter substrate 5 .

[0049] The second polarizer 6 is arranged on the side of the color film substrate 5 away from the backlight module 1. The basic structure of the second polarizer 6 includes: PVA (polyvinyl alcohol) and TAC (triacetyl cellulose) arranged on both sides of the PVA. The PVA layer plays a polarizing role, but PVA is very easy to hydrolyze. In order to protect the physical properties of the polarizing film, a layer of (TAC) film with high light transmittance, good water resistance and certain mechanical strength is compounded on both sides of the PVA for protection. The polarization direction of the second polarizer 6 is perpendicular to the polarization direction of the first polarizer 2.

[0050] In this embodiment, the viewing angle expansion film 7 is disposed between the color filter substrate 5 and the second polarizer 6. In other embodiments, the viewing angle expansion film 7 may also be disposed on a side of the second polarizer 6 away from the backlight module 1.

[0051] like Figure 2 , Figure 3 , Figure 5 As shown, the viewing angle expansion film 7 includes: a first film layer 71 , a second film layer 72 and a substrate 73 .

[0052] The substrate 73 has a light incident surface 731 and a light emitting surface 732 which are arranged opposite to each other. It is worth noting that the light incident surface 731 of the substrate 73 refers to the surface of the substrate 73 on the side close to the backlight module 1. The material of the substrate 73 can be transparent glass. Therefore, the substrate 73 has good light transmission performance when supporting the first film layer 71 and the second film layer 72 thereon.

[0053] The first film layer 71 is disposed on the light emitting surface 732 of the substrate 73. The material of the first film layer 71 is a first resin. In this embodiment, the material of the first film layer 71 is a first light-transmitting resin. The refractive index of the first film layer 71 is in the range of 1.3-1.6. In this embodiment, the refractive index of the first film layer 71 is 1.4.

[0054] The first film layer 71 includes a flat layer 711 and a plurality of first protrusions 712 and a plurality of second protrusions 713 disposed on the flat layer 711 .

[0055] The flat layer 711 is disposed on the light emitting surface 732 of the substrate 73. The flat layer 711 mainly provides a flat surface for preparing the first protrusion 712 and the second protrusion 713 thereon. The thickness of the flat layer 711 ranges from 1 micron to 10 microns. In this embodiment, the thickness of the flat layer 711 is 5 microns.

[0056] In other embodiments, the first film layer 71 further includes a plurality of scattering particles. The scattering particles are used to enhance the diffusion effect of the viewing angle expansion film 7. The scattering particles are preferably circular scattering particles, the diameter of the scattering particles ranges from 0.05 microns to 2 microns, the content of the scattering particles ranges from 1% to 30%, and the material of the scattering particles can be selected from inorganic materials such as silicon dioxide, titanium dioxide, barium sulfate, calcium carbonate, zirconium dioxide, etc., and can also be selected from organic particle materials such as polymethyl methacrylate (PMMA) particles, polycarbonate (PC) particles, and polystyrene (PS) particles.

[0057] like Figure 4 As shown, the first protrusions 712 are spaced apart from each other along a first direction X and a second direction Y perpendicular to the first direction X and are arranged in an array on the planar layer 711 .

[0058] like Figure 4 , Figure 5 As shown, the extension direction of the first protrusions 712 is parallel to the first direction X. Specifically, each of the first protrusions 712 includes a first inclined surface 7121 and a second inclined surface 7122 , and a first intersection line between the first inclined surface 7121 and the flat layer 711 and a second intersection line between the second inclined surface 7122 and the flat layer 711 are parallel to the first direction X.

[0059] like Figure 4 As shown, the second protrusions 713 are spaced apart from each other along the first direction X and the second direction Y and are arranged in an array on the flat layer 711 , and are spaced apart from the first protrusions 712 .

[0060] like Figure 4 , Figure 7As shown, the extension direction of the second protrusions 713 is parallel to the second direction Y; each of the second protrusions 713 includes a third inclined surface 7131 and a fourth inclined surface 7132, and the third intersection line between the third inclined surface 7131 and the flat layer 711 and the fourth intersection line between the fourth inclined surface 7132 and the flat layer 711 are both parallel to the second direction Y.

[0061] like Figure 2 , Figure 3 and Figure 5 As shown, the second film layer 72 is disposed on the first film layer 71, and fills the gap between the adjacent first protrusions 712 and the second protrusions 713, the gap between two adjacent first protrusions 712, and the gap between two adjacent second protrusions 713. The material of the second film layer 72 is a second resin. In this embodiment, the material of the second film layer 72 is a second light-transmitting resin. The refractive index of the second film layer 72 is greater than the refractive index of the first film layer 71. The refractive index of the second film layer 72 ranges from 1.5 to 1.9. In this embodiment, the refractive index of the second film layer 72 is 1.7.

[0062] In other embodiments, the second film layer 72 further includes a plurality of scattering particles. The scattering particles are used to enhance the diffusion effect of the viewing angle expansion film 7. The scattering particles are preferably circular scattering particles, the diameter of the scattering particles ranges from 0.05 microns to 2 microns, the content of the scattering particles ranges from 1% to 30%, and the material of the scattering particles can be selected from inorganic materials such as silicon dioxide, titanium dioxide, barium sulfate, calcium carbonate, zirconium dioxide, etc., and can also be selected from organic particle materials such as polymethyl methacrylate (PMMA) particles, polycarbonate (PC) particles, and polystyrene (PS) particles.

[0063] In summary, in this embodiment, the light is diffused in the second direction Y by the first inclined surface 7121 and the second inclined surface 7122 of the first protrusion 712; the light is diffused in the first direction X by the third inclined surface 7131 and the fourth inclined surface 7132 of the second protrusion 713; so that the viewing angle expansion film 7 can diffuse the light in the first direction X and the second direction Y at the same time, thereby simultaneously expanding the viewing angle of the display device 100 in the first direction X and the second direction Y.

[0064] In the first direction X and / or the second direction Y, the first protrusions 712 and the second protrusions 713 are arranged alternately.

[0065] like Figure 4 As shown, in this embodiment, in the second direction Y, the first protrusions 712 and the second protrusions 713 are alternately arranged. The first protrusions 712 and the second protrusions 713 are arranged periodically, thereby improving the light uniformity of the display device 100.

[0066] like Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, the first protrusion 712 and the second protrusion 713 have the same shape and size. In this embodiment, the shape of the first protrusion 712 is an isosceles trapezoidal prism. In other words, the shape of the first protrusion 712 on the cross section formed by the second direction Y and the third direction Z is an isosceles trapezoid.

[0067] like Figure 6 As shown, the edge length L of the first protrusion 712 1 In this embodiment, the edge length L of the first protrusion 712 is 2 microns to 60 microns. 1 is 40 microns.

[0068] like Figure 6 As shown, on the BB section parallel to the first direction X, the distance L between two adjacent first protrusions 712 is 2 and the edge length L of the first protrusion 712 1 The sum of L is in the range of 20 microns to 80 microns. 2 10 microns, L 1 and L 2 The sum is 50 microns.

[0069] like Figure 5 As shown, the included angle θ between the first inclined surface 7121 of the first protrusion 712 and the flat layer 711 is greater than 0° and less than 80°. In this embodiment, the included angle θ between the first inclined surface 7121 of the first protrusion 712 and the flat layer 711 is 70°.

[0070] like Figure 5 As shown, on the AA section parallel to the second direction Y, the first protrusion 712 is perpendicular to the lower base L of the section of the edge length. 3 The width of the length ranges from 5 microns to 20 microns. 3 The height H of the first protrusion 712 is in the range of 4 micrometers to 20 micrometers; in this embodiment, H is 8 micrometers.

[0071] like Figure 5 As shown, on the AA section parallel to the second direction Y, the distance L between two adjacent second protrusions 713 is 4 and the edge length L of the second protrusion 713 1 The sum of L is in the range of 20 microns to 100 microns. 4 =L 3 +L 5 +L 6 In this embodiment, L 5 =L6 = 12 Micrometer, at this time L 4 =34 microns.

[0072] like Figure 7 As shown, on the CC section parallel to the first direction X, the distance L between two adjacent second protrusions 713 is 7 and the length L of the lower base of the cross section of the second protrusion 713 perpendicular to its edge length 3 The sum of L is in the range of 20 microns to 80 microns. 7 30 microns, L 7 and L 3 The sum is 40 microns.

[0073] In summary, by periodically arranging the first protrusions 712 and the second protrusions 713 , the light uniformity of the display device 100 in the first direction X and the second direction Y can be improved.

[0074] like Figure 8 As shown, the present embodiment also provides a method for preparing the viewing angle expansion film 7 of the present embodiment, which comprises the following steps: S1, providing a substrate 73; S2, arranging a first film layer 71 on the substrate 73; the first film layer 71 comprises a flat layer 711 and a plurality of first protrusions 712 and a plurality of second protrusions 713 arranged on the flat layer 711; the first protrusions 712 are spaced from each other along a first direction X and a second direction Y perpendicular to the first direction X and are arranged in an array on the flat layer 711, and the extension direction of the first protrusions 712 is parallel to the first direction X; the second protrusions 713 are arranged along a first direction X and a second direction Y perpendicular to the first direction X. The first direction X and the second direction Y are spaced apart from each other and arranged in an array on the flat layer 711, and are spaced apart from the first protrusions 712, and the extension directions of the second protrusions 713 are parallel to the second direction Y; S3, a second film layer 72 is arranged on the first film layer 71, and the second film layer 72 fills the gap between adjacent first protrusions 712 and second protrusions 713, the gap between two adjacent first protrusions 712, and the gap between two adjacent second protrusions 713, and the refractive index of the second film layer 72 is greater than the refractive index of the first film layer 71.

[0075] Specifically, S2 includes providing a flat layer 711 on the light-emitting surface of the substrate 73. Specifically, S2 includes coating a first resin on the light-emitting surface 732 of the substrate 73 using a slit coater, and then curing the first resin to form the flat layer 711.

[0076] Specifically, S2 further includes: using a slit coater to coat a first resin on a surface of the flat layer 711 away from the substrate 73, and then performing exposure and development patterning to obtain a plurality of first protrusions 712 and a plurality of second protrusions 713. The flat layer 711, the first protrusions 712, and the second protrusions 713 together form the first film layer 71.

[0077] Specifically, S3 includes coating the first film layer 71 with a second resin using a slit coater, filling the second resin in the gap between the adjacent first protrusions 712 and the second protrusions 713, the gap between two adjacent first protrusions 712, and the gap between two adjacent second protrusions 713, and then curing to form the second film layer 72. The first film layer 71 and the second film layer 72 together form the viewing angle expansion film 7.

[0078] Example 2

[0079] like Fig. 9 As shown, this embodiment includes most of the technical features of the embodiment 1, and the difference between this embodiment and the embodiment 1 is that in this embodiment, the first protrusions 712 and the second protrusions 713 are alternately arranged in the first direction X and the second direction Y. Thus, the light uniformity of the display device 100 in the first direction X and the second direction Y can be further improved.

[0080] The above is a detailed introduction to a viewing angle expansion film and its preparation method and display device provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A viewing angle expansion film, characterized in that: include: A first film layer, comprising a flat layer and a plurality of first protrusions and a plurality of second protrusions disposed on the flat layer, wherein the plurality of first protrusions are spaced from each other along a first direction and a second direction perpendicular to the first direction and are arranged in an array on the flat layer, wherein the extension directions of the first protrusions are all parallel to the first direction, and the size of the first protrusions in the first direction is greater than the size of the first protrusions in the second direction; A plurality of second protrusions are spaced from each other along the first direction and the second direction and are arranged in an array on the flat layer and are spaced from the first protrusions. The extension directions of the second protrusions are parallel to the second direction. The size of the second protrusions in the second direction is greater than the size of the second protrusions in the first direction. a second film layer, disposed on the first film layer and filling a gap between adjacent first protrusions and the second protrusions, a gap between two adjacent first protrusions, and a gap between two adjacent second protrusions, wherein the refractive index of the second film layer is greater than the refractive index of the first film layer; Wherein, each of the first protrusions includes a first inclined plane and a second inclined plane, and a first intersection line between the first inclined plane and the flat layer and a second intersection line between the second inclined plane and the flat layer are both parallel to the first direction; each of the second protrusions includes a third inclined plane and a fourth inclined plane, and a third intersection line between the third inclined plane and the flat layer and a fourth intersection line between the fourth inclined plane and the flat layer are both parallel to the second direction; in the first direction and / or the second direction, the first protrusions and the second protrusions are alternately arranged.

2. The viewing angle expansion film according to claim 1, characterized in that: The first film layer and / or the second film layer further include a plurality of scattering particles, and the content of the scattering particles ranges from 1% to 30%.

3. The viewing angle expansion film according to claim 1, characterized in that: The refractive index of the material of the first film layer is in the range of 1.3-1.6; the refractive index of the material of the second film layer is in the range of 1.5-1.

9.

4. The viewing angle expansion film according to claim 1, characterized in that: The first protrusion and the second protrusion have the same shape and size, and the first protrusion is in the shape of an isosceles trapezoidal prism; The edge length of the first protrusion ranges from 2 microns to 60 microns, and the height of the first protrusion ranges from 4 microns to 20 microns; the angle between the first inclined surface of the first protrusion and the flat layer is greater than 0° and less than 80°, and the width of the lower bottom length of the cross section of the first protrusion perpendicular to the edge length ranges from 5 microns to 20 microns.

5. The viewing angle expansion film according to claim 4, characterized in that: On a cross section parallel to the second direction, the sum of the distance between two adjacent second protrusions and the edge length of the second protrusion is in a range of 20 micrometers to 100 micrometers; On a cross section parallel to the first direction, the distance between two adjacent first protrusions and the sum of the edge lengths of the first protrusions range from 20 microns to 80 microns, and the distance between two adjacent second protrusions and the sum of the bottom lengths of the cross section of the second protrusions perpendicular to their edge lengths range from 20 microns to 80 microns.

6. A method for preparing a viewing angle expansion film, characterized in that: The following steps are involved: providing a substrate; A first film layer is provided on the substrate; the first film layer comprises a flat layer and a plurality of first protrusions and a plurality of second protrusions provided on the flat layer, the plurality of first protrusions are spaced from each other along a first direction and a second direction perpendicular to the first direction and are arranged in an array on the flat layer, the extension directions of the first protrusions are all parallel to the first direction, and the size of the first protrusions in the first direction is larger than the size of the first protrusions in the second direction; the plurality of second protrusions are spaced from each other along the first direction and the second direction and are arranged in an array on the flat layer, and are spaced from the first protrusions, the extension directions of the second protrusions are all parallel to the second direction, and the size of the second protrusions in the second direction is larger than the size of the second protrusions in the first direction; A second film layer is disposed on the first film layer, the second film layer fills the gap between the adjacent first protrusions and the second protrusions, the gap between two adjacent first protrusions, and the gap between two adjacent second protrusions, and the refractive index of the second film layer is greater than the refractive index of the first film layer; Wherein, each of the first protrusions includes a first inclined plane and a second inclined plane, and a first intersection line between the first inclined plane and the flat layer and a second intersection line between the second inclined plane and the flat layer are both parallel to the first direction; each of the second protrusions includes a third inclined plane and a fourth inclined plane, and a third intersection line between the third inclined plane and the flat layer and a fourth intersection line between the fourth inclined plane and the flat layer are both parallel to the second direction; in the first direction and / or the second direction, the first protrusions and the second protrusions are alternately arranged.

7. The method for preparing a viewing angle widening film according to claim 6, characterized in that: The step of providing a first film layer on the substrate comprises: Disposing a flat layer on the light emitting surface of the substrate; A first resin is coated on the surface of the flat layer at a side away from the substrate, and a plurality of first protrusions and a plurality of second protrusions are obtained after exposure, development and patterning.

8. A display device, characterized in that: The viewing angle-enlarging film comprises the viewing angle-enlarging film according to any one of claims 1 to 5.

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