CN209961930U - Anti-reflection film - Google Patents

Abstract

The utility model discloses the problem is "antireflection membrane". An anti-reflective membrane is provided that includes a plurality of substantially similar generally spherical protrusions. The average diameter of the protrusions is greater than or equal to 1 micrometer (μm) and less than or equal to 30 μm. Further, the protrusions substantially form a monolayer or bilayer and the protrusions occupy at least 35% of the area of the monolayer or bilayer. Further, a value defined by the following equation is greater than or equal to 1 and less than or equal to 1.7: the value NN6/NN1, where NN1 is the distance between one protrusion and another protrusion closest to the protrusion, and NN6 is the distance between the protrusion and the sixth other protrusion closest to the protrusion.

Description

Anti-reflection film

Technical Field

The present disclosure generally relates to anti-reflective films for display surfaces.

Background

Electronic displays, such as Liquid Crystal Displays (LCDs) and Organic Light Emitting Diodes (OLEDs), are used in a variety of devices, such as televisions, computer monitors, electronic shelf labels, electronic books and digital signage, and indoor signage and display cases. The display surface of such electronic displays has the disadvantage of surface reflection, which prevents the consumer from capturing all of the information provided by the display surface. This problem occurs frequently in daily life, and therefore reflection reduction is required. There are some commercially available antireflective films. Such anti-reflection films are generally prepared by coating a set of high refractive index material and low refractive index material on a substrate by wet coating or sputtering/vapor deposition coating. Multiple sets of such layers (multilayer coatings) need to be applied to accommodate a wide range of visible wavelengths. Therefore, the antireflection film is generally expensive.

In order to solve the above problem, a film having a specular reflectance of at least less than 0.2% is desired. Anti-reflective films with multiple vapor deposition coatings meet this requirement but are expensive. Furthermore, continuous single-set sputtered (single-layer coated) films are expensive, and it is also difficult to achieve the target reflectivity with such films. Another wet monolayer coating film, which is not very expensive, has a reflectivity of about 1.5%. Recently, a new moth-eye structure using a nanoimprint technology has been proposed, but commercialization has not been achieved due to difficulties in large-scale formatting and roll processing.

OLEDs are an emerging electronic display technology that is widely expected due to their high luminous efficiency. OLEDs are also used in the lighting industry because it reduces power consumption. However, the emitted light is reflected towards the inside at the OLED/glass boundary, or the light from this boundary is reflected again towards the inside at the glass/air boundary. Therefore, almost 80% of the emitted light is inside the device, and only 20% of the light is emitted to the outside. Accordingly, there is a need for improved anti-reflective films.

SUMMERY OF THE UTILITY MODEL

Generally, the present disclosure relates to anti-reflective films. The present disclosure also relates to anti-reflective films for use with displays such as LCDs, OLEDs, digital signage, passive signage in a room, display cases, graphics, or stray light. Anti-reflective films can also be used to reduce the optical loss of the device at the optical boundary.

In one embodiment of the present disclosure, the anti-reflective film comprises a plurality of substantially similar generally spherical protrusions. The average diameter of the protrusions is greater than or equal to 1 micrometer (μm) and less than or equal to 30 μm. Further, the protrusions substantially form a single layer or a double layer. The protrusions occupy at least 35% of the area of the monolayer or bilayer. Further, a value defined by the following equation is greater than or equal to 1 and less than or equal to 1.7: the value NN6/NN1, where NN1 is the distance between one projection and the other projection closest to the projection, and NN6 is the distance between the projection and the sixth projection closest to the projection.

In some embodiments, the total reflectance of the anti-reflective film is 5% or less.

In some embodiments, the anti-reflective film includes a substrate and a transparent resin layer bonding a single layer or a double layer of the plurality of protrusions to the substrate. Further, the protrusion includes particles.

In some embodiments, the standard deviation of the particles is 70% or less of the average diameter of the particles.

In some embodiments, the protrusions are microreplicated structures.

Drawings

The present invention may be more completely understood in consideration of the following detailed description in connection with the accompanying drawings. The figures are not necessarily to scale. Like numbers used in the figures refer to like elements. It should be understood, however, that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.

FIG. 1 shows a schematic view of an exemplary anti-reflective film having a single layer;

fig. 2 shows a schematic view illustrating an anti-reflection characteristic of a protrusion of the anti-reflection film of fig. 1.

Fig. 3 shows measured antireflection films having NN1 and NN 6;

FIG. 4 shows a schematic view of another exemplary anti-reflective film having a single layer;

fig. 5 and 6 show exemplary bead size distributions for two samples;

FIG. 7 is an exemplary graph illustrating total reflection spectra for some samples;

FIG. 8 is an exemplary graph illustrating specular reflectance spectra for some samples;

FIG. 9 is an exemplary graph showing the reflectance spectra of some samples;

FIG. 10 is an exemplary graph showing the reflectance spectra of some samples;

FIG. 11 shows a schematic view of another exemplary anti-reflective film having a bilayer;

FIG. 12 is an exemplary graph illustrating specular reflection data for some samples;

FIG. 13 is an exemplary graph illustrating total reflection data for some samples;

FIG. 14 is an exemplary anti-reflective film sample having a microreplicated structure;

FIG. 15 is a cross-sectional view of the anti-reflection film sample of FIG. 14 taken along section A-A1; and

fig. 16 is an exemplary graph illustrating bead coverage for various samples.

Detailed Description

In the following description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration various embodiments. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description is, therefore, not to be taken in a limiting sense.

Fig. 1, 4, 11, and 14 show schematic views of exemplary anti-reflection films 100, 400, 1200, and 1602, respectively. The anti-reflection film 100, 400, 1200, 1602 may be used as an anti-reflection film in an LCD device, a light extraction efficiency improvement film on an OLED device, an anti-reflection film for digital signage, an anti-reflection film for indoor passive signage, a compensation film for device optical loss at an optical boundary, an anti-reflection film for showcases, an anti-reflection film for graphics, or a pure black absorption film for stray light. In some embodiments, the total reflectance of each anti-reflective film 100, 400, 1200, 1602 is 5% or less.

The anti-reflection film 100 will now be described in detail with reference to fig. 1. The antireflection film 100 includes a substrate 102. In the embodiment shown, the substrate 102 is polyethylene terephthalate (PET). Further, in some embodiments, the substrate 102 may include a transparent silicon dioxide or siloxane compound film. Alternatively, the substrate 102 may be made of different materials based on application requirements. Further, in some implementations, the substrate 102 can be a black film to absorb stray light. The black film may contain a black pigment in a resin or be coated with a black pigment. Further, the antireflection film 100 includes a transparent resin 104. The transparent resin layer 104 is disposed on the substrate 102. The transparent resin 104 may include an optically clear adhesive.

The anti-reflection film 100 includes a plurality of almost similar substantially spherical protrusions 106. The term "substantially spherical" means that each protrusion 106 has a slight deviation from a perfect spherical shape due to manufacturing. Each projection 106 defines a diameter "D". The term "nearly similar" means that the variation in diameter "D" on the tab 106 is minimal. In some examples, the protrusion 106 may comprise a spherical shape or an elliptical shape. In the embodiment shown, the projections 106 form a single layer 108. The transparent resin 104 bonds a single layer 108 of the plurality of protrusions 106 to the substrate 102. It should be noted that the term "protrusion" may be interchangeably referred to hereinafter as a "bead" without limiting the scope of the present disclosure. Further, in one example, the projections 106 may be implemented as particles. The particles may be dispersed in a resin and then coated on the substrate 102 to form the anti-reflection film 100. In some embodiments, the particles dispersed in transparent resin 104 are coated on substrate 102 by using a very narrow coating gap or thickness. Further, a single layer 108 (shown in fig. 1) of protrusions 106, a single layer 408 (shown in fig. 4) of protrusions 406 (shown in fig. 4), or a double layer 1208 (shown in fig. 11) of protrusions 1206 (shown in fig. 11) may be obtained depending on the coating gap.

In one embodiment, each tab 106 is made of a polymeric material, such as acrylic beads. The protrusion 106 may be implemented as transparent particles including a transparent glass material, a single crystal, or a transparent synthetic resin. Polycrystalline material may also be used to fabricate the protrusions 106, as long as low refraction or light scattering is exhibited at the intercrystalline interfaces. In some cases, the protrusion 106 may be made of a material having high hardness and chemical resistance, a refractive index of less than 2, and preferably less than 1.7. In some cases, the material of the protrusion 106 includes silica, alumina or magnesia, glass powder such as soda glass, borosilicate glass, or the like, or natural or synthetic resin.

In one embodiment, the plurality of projections 106 are arranged at a pitch. The spacing may be defined as the distance "Pi" between the centers of adjacent projections 106. In some cases, each tab 106 of the plurality of tabs 106 is surrounded by six tabs 106. Further, the diameter "D" of each protrusion 106 may have a small variation due to a shape defect of each protrusion 106. Each protrusion 106 is generally spherical in shape due to minor variations. Further, the projections 106 may have nearly similar diameters. In other words, the variation in diameter "D" across the protrusion 106 may be small. For example, the diameter "D" varies across the protrusion 106 by a small percentage. In one example, the diameter "D" of each protrusion 106 has a variation of less than or equal to 5%. Variations in diameter "D" across the projection 106 may be minimized. The diameter "D" of each protrusion 106 may also have a small value. The smaller protrusions 106 have a higher packing density and therefore surface reflection is also small. In addition, the space between adjacent projections 106 may also be minimized.

In some examples, the diameter "D" of the protrusion 106 is approximately between 0.8 μm and 3 μm to achieve low surface reflection. This is because the protrusions 106 having a smaller diameter (such as less than 1 μm) exhibit characteristics similar to those of the antireflection film having a plurality of coating layers. In this case, the intermediate visible wavelength has the lowest surface reflection, and the low and high visible wavelength reflections have surface reflections that are greater than the surface reflection of the intermediate visible wavelength. Further, the reflection spectrum curve of such an antireflection film is concave. It should be further noted that the ideal diameter "D" of the protrusion 106 that provides optimal surface reflection is approximately between 1.5 μm and 2 μm.

In one embodiment, the average diameter "Da" of the projections 106 is greater than or equal to 1 μm and less than or equal to 30 μm. The average diameter "Da" may be selected based on the desired anti-reflection characteristics of the anti-reflection film 100. The average diameter "Da" may be equal to the average of the diameters "D" of the projections 106. For the antireflection film 100, the average diameter "Da" is used due to the variation in diameter "D" across the protruding portion 106. Further, the protrusions 106 occupy at least 35% of the area of the single layer 108.

The operation principle of the anti-reflection film 100 will now be explained with reference to fig. 2. In operation, the hemispherical protrusion surfaces 112, 114 at the upper portions 116, 117 of the respective protrusions 118, 120 act as anti-reflection surfaces by providing a light reflection feature between two adjacent protrusion surfaces 112, 114. The protrusion surfaces 112, 114 may be referred to as a first protrusion surface 112 and a second protrusion surface 114. Thus, by reflection on the first protrusion surface 112 of the protrusion 118 close to 90 degrees, light may be incident at 0 degrees on the second protrusion surface 114 of the protrusion 120. On the other hand, by the reflection on the first protrusion surface 112 being close to 0 degree, light may be incident on the second protrusion surface 114 at 90 degrees. During each reflection, a portion of the light is refracted by the protrusions 118, 120. Therefore, the repeated reflection on the adjacent protruding portions 118, 120 can impart the antireflection film 100 with antireflection characteristics.

In addition, the antireflection film 100 has a limit value. This value is greater than or equal to 1 and less than or equal to 1.7. Further, the value is defined by the following equation:

value NN6/NN1 … equation (I)

As shown in fig. 3, NN1 is the distance between a tab 122 and another tab 124 closest to the tab 122, NN2 is the distance between the tab 122 and another tab 126 second closest to the tab 122, NN3 is the distance between the tab 122 and another tab 128 third closest to the tab 122, NN4 is the distance between the tab 122 and another tab 130 fourth closest to the tab 122, NN5 is the distance between the tab 122 and another tab 132 fifth closest to the tab 122, and NN6 is the distance between the tab 122 and another tab 134 sixth closest to the tab 122. Further, distances NN1, NN2, NN3, NN4, NN5, NN6 are measured between the centers of the respective projections. For example, a distance NN1 is measured between the center of protrusion 122 and the center of protrusion 124. Furthermore, the projections 122, 124, 126, 128, 130, 132 shown in the figures are embodied as particles.

It should be noted that the Atomic Force Microscope (AFM) height map of each sample measures the kth nearest neighbor distance (NNk) for k 1 to N, where N is greater than or equal to 6 and the upper limit is 100. N is limited by the protrusion 106. Further, the NN1 divides the antireflection film 100 into groups of protrusions 106 having similar sizes. The density of the protrusions 106 is several thousand protrusions per square millimeter, and the total area is the sum of the areas measured for each anti-reflection film 100.

Table 1 provided below shows various types of samples of the antireflection film 100, 400, 1200, or 1602. The corresponding diameters "D", total area, bead density and values of NN1 and NN6/NN1 for the samples are also shown in table 1.

Table 1: sample Properties

As shown above, the values of NN6/NN1 group the antireflection film 100 into three groups, which vary based on their stacked arrangement. For example, NN6/NN1 may be substantially equal to one of the microreplicated structures, such as for protrusions 1604 (see fig. 15) arranged in a full hexagonal pattern consisting of a hexagonal close-packed arrangement of protrusions. More specifically, NN6 may be substantially equal to NN1 for microreplicated structures, and thus the values of NN6/NN1 may be substantially equal to 1 for microreplicated structures. Further, the projections 106 of some of the samples shown above (e.g., example 4) were arranged in an approximately hexagonal arrangement, resulting in the values of NN6/NN1 clustered around 1.4. Furthermore, another sample provided in table 1, designated as example 3, had large dimples that disrupted the hexagonal arrangement on the sheet, resulting in a value of NN6/NN1 of about 1.8. Therefore, NN6/NN1 divides the antireflection film 100 into three groups, which differ in the stacking arrangement. The term "depression" referred to herein may be defined as a flat area without protrusions 106.

It should be further noted that, in some examples, the samples with single- layer protrusions 106, 406 used in graphs 602, 702, 802, 902, 1002, 1102, 1402, 1502 may include any of the embodiments, i.e., the one with embedded deeper single-layer bead coatings provided in table 1

Example 5, example 3 with bead coating with dimples provided in table 1, and example 4 with single bead coating provided in table 1. It should be further noted that example 2 in table 1 is for samples with two layers or bilayers of protrusions, while example 6, example 7 and example 8 are microreplicated samples. In one embodiment, the standard deviation of the projections 106 is 70% or less of the average diameter "Da" of the projections 106. In other words, when the protrusions 106 are embodied as particles (as shown in fig. 1), the standard deviation of the particle diameters is 70% or less of the average particle diameter.

Fig. 4 illustrates another embodiment of the present disclosure. The anti-reflection film 400 of this embodiment includes a single layer 408 of protrusions 406, similar to the single layer 108 of protrusions 106 of the anti-reflection film 100. In addition, the antireflection film 400 further includes a substrate 402 and a transparent resin layer 404, which are similar to the substrate 102 and the transparent resin layer 104 of the antireflection film 100, respectively. In addition, the anti-reflection film 400 includes another transparent resin layer 405. The transparent resin layer 405 is disposed on the upper surface of the protrusion 406. The transparent resin 405 may be the same resin as the transparent resin 404.

Fig. 5, 6 and 7 will now be described in detail. It should be noted that two types of samples, i.e., sample "S1" and sample "S2" are used to explain fig. 5, 6, and 7. Sample "S1" has a narrow particle size distribution with particles having an average diameter "Da" of 3 μm. Further, the sample "S2" has a broad particle size distribution in which the average diameter "Da" of the particles is 3 μm. It should be noted that the samples referred to in fig. 7 to 10 include a substrate 102 having a thickness of about 100 μm and manufactured by Toyobo corporation. The transparent resin layer 104 had a thickness of about 80 μ M and was manufactured by 3M company.

Fig. 5 shows an exemplary graph 602 generated by plotting points corresponding to sample "S1". Sample "S1" included beads or protrusions without a resin layer. Particle size is marked on the X-axis and sample volume is marked on the Y-axis. The pattern 604 is generated by plotting points corresponding to various readings of the sample "S1". The mean of sample "S1" is approximately 2.727, the median of sample "S1" is approximately 2.486, the mean/median ratio is approximately 1.096, the pattern of sample "S1" is 2.538, the variance of sample "S1" is 0.524, the Coefficient of Variance (CV) of sample "S1" is 26.55, the skewness of sample "S1" is 1.78, and the kurtosis of sample "S1" is 1.60. Further, the standard deviation of the sample "S1" is approximately equal to 0.72. Thus, graph 602 shows that the standard deviation of the narrow size distribution of the particles is less than 70% of the average diameter "Da" of the particles.

Fig. 6 shows an exemplary graph 702 generated by plotting points corresponding to sample "S2". Sample "S2" included beads or protrusions without a resin layer. The particle size is marked on the X-axis and the sample volume is marked on the Y-axis. The pattern 704 is generated by plotting points corresponding to various readings of the sample "S2". The mean of sample "S2" is approximately 4.564, the median of sample "S2" is approximately 4.095, the mean/median ratio is approximately 1.114, the pattern of sample "S2" is approximately 2.312, the variance of sample "S2" is 5.59, the CV of sample "S2" is 51.81, the skewness of sample "S2" is 0.837, and the kurtosis of sample "S2" is-0.208. Further, the standard deviation of the sample "S2" is approximately equal to 2.364. Thus, graph 702 shows that the standard deviation of the broad size distribution of the particles is less than 70% of the average diameter "Da" of the particles. It should be noted, however, that the standard deviation of the narrow size distribution of the particles is less than the standard deviation of the broad size distribution of the particles.

Referring now to fig. 7, an exemplary graph 802 illustrating total reflection spectra for some samples is shown. Wavelengths in nanometers (nm) are marked on the X-axis and reflections in percent are marked on the Y-axis. The pattern 804 is generated by plotting points corresponding to the various readings of sample "S2", while the pattern 806 is generated by plotting points corresponding to the various readings of sample "S1". As shown, the reflectance was lower for the sample with "S1" having a narrow bead size distribution, and higher for the sample with "S2" having a broad bead size distribution. Thus, a narrow bead size distribution results in lower reflection, which in turn provides better anti-reflection performance.

Fig. 8, 9, and 10 are exemplary graphs 902, 1002, 1102 illustrating reflection spectra corresponding to different samples. Fig. 8 is an exemplary graph 902 illustrating specular reflection spectra for some samples. The wavelength in nm is marked on the X-axis and the reflection in percent is marked on the Y-axis. In this embodiment, the sample used to plot graph 902 includes a protrusion 1604 (see fig. 15) that is integral with the substrate 102. A graph 902 is prepared by plotting the results of three different samples. More specifically, the pattern 904 was generated by plotting points corresponding to various readings of the microreplicated samples of example 6 provided in table 1, having a pitch of 20 μm and providing some space between adjacent protrusions 1604. The pattern 906 was generated by plotting points corresponding to various readings of the microreplicated samples of example 7 provided in table 1, having a pitch of 20 μm and a dense structure of protrusions 1604. The pattern 908 was created by plotting points corresponding to various readings for the sample of example 8 provided in table 1, which had a pitch of 7 μm and a dense structure of protrusions 1604. Graph 902 shows that protrusions 106 of similar diameter have good anti-reflection properties.

Fig. 9 is an exemplary graph 1002 showing the reflectance spectra of some samples. The wavelength in nm is marked on the X-axis and the reflection in percent is marked on the Y-axis. The sample used to plot 1002 was implemented as a structured anti-reflection film. Graph 1002 is prepared by plotting the results of three different samples. More specifically, the pattern 1004 is generated by drawing dots corresponding to various readings of the sample using "S1" particles on an Optically Clear Adhesive (OCA) or clear resin (similar to fig. 1). Pattern 1006 was created by plotting points corresponding to various readings of the sample of example 9 provided in table 1, having a black surface coating, 10 μm in diameter. Pattern 1008 was generated by plotting points corresponding to various readings of the sample of example 10 provided in table 1, having a black surface coating, 20 μm in diameter. Graph 1002 shows that the structured anti-reflection film exhibits high anti-reflection properties.

Fig. 10 is an exemplary graph 1102 showing the reflectance spectra of some samples. The wavelength in nm is marked on the X-axis and the reflection in percent is marked on the Y-axis. The sample used to plot the graph 1102 is implemented as a structured anti-reflection film. A graph 1102 is prepared by plotting the results for seven different samples. More specifically, the pattern 1104 is generated by drawing points corresponding to various readings of the sample using "S4" particles having a diameter of 0.8 μm. The pattern 1106 was generated by drawing points corresponding to various readings of the sample using "S5" particles of 1 μm diameter. The pattern 1108 was generated by drawing points corresponding to various readings of the sample using an "S6" particle of 1.5 μm diameter. The pattern 1110 was generated by drawing points corresponding to various readings of the sample using a 2 μm diameter "S7" particle. The pattern 1112 is generated by drawing points corresponding to various readings of the sample using the "S1" particle. The pattern 1114 was generated by plotting points corresponding to various readings for the 10 μm diameter sample of example 9 provided in table 1. The pattern 1116 was generated by plotting points corresponding to various readings for the sample of example 10 provided in table 1, which sample had a diameter of 20 μm. Graph 1102 shows that the structured anti-reflection film exhibits high anti-reflection properties.

Fig. 11 shows an antireflection film 1200. The antireflection film 1200 includes a substrate 1202. In the embodiment shown, the substrate 1202 may be polyethylene terephthalate (PET). Further, in some embodiments, the substrate 1202 may include a transparent silicon dioxide or siloxane compound film. Alternatively, the substrate 1202 may be made of different materials based on application requirements. Further, in some implementations, the substrate 1202 can be a black film to absorb stray light. The black film may contain a black pigment in a resin or be coated with a black pigment. Further, the antireflection film 1200 includes a transparent resin 1204. A transparent resin layer 1204 is provided on the substrate 1202. The transparent resin 1204 may include OCA. In addition, in the illustrated embodiment, the anti-reflection film 1200 further includes another transparent resin layer 1205. A transparent resin layer 1205 is disposed on the upper surface of the protrusion 1206. The transparent resin 1205 may be the same resin as the transparent resin 1204. However, it should be noted that the antireflection film 1200 may omit the transparent resin layer 1205 without limiting the scope of the present disclosure.

The anti-reflection film 1200 includes a number of almost similar substantially spherical protrusions 1206. The term "substantially spherical" means that each protrusion 1206 has a slight deviation from a perfect spherical shape due to the manufacturing process. The term "nearly similar" means that the variation in diameter "D1" on the projection 1206 is minimal. In some examples, the protrusion 1206 may comprise a sphere or an ellipse. As shown, in the illustrated embodiment, the projections 1206 form a bilayer 1208. A transparent resin 1204 bonds the bilayer 1208 of the plurality of protrusions 1206 to the substrate 1202. Furthermore, the projections 1206 may be implemented as particles. The particles may be dispersed in a resin and then coated on the substrate 1202 to form the anti-reflection film 1200. In some embodiments, particles dispersed in transparent resin 1204 are coated on substrate 1202 by using a very narrow coating gap or thickness. Further, the double layer 1208 of the projection 1206 may be obtained according to the coating gap.

In one embodiment, each tab 1206 is made of a polymeric material, such as acrylic beads. Further, the protrusion 1206 may be implemented as transparent particles including a transparent glass material, a single crystal, or a transparent synthetic resin. Polycrystalline material may also be used to fabricate the protrusions 1206, as long as low refraction or light scattering is exhibited at the intercrystalline interfaces. In some cases, the protrusions 1206 may be made of a material having high hardness and chemical resistance, a refractive index of less than 2, and preferably less than 1.7. In some cases, the material of the projections 1206 includes silicon dioxide, aluminum oxide, or magnesium oxide, glass powder such as soda glass, borosilicate glass, or the like, or natural or synthetic resin. In one embodiment, the plurality of protrusions 1206 are arranged at a pitch. This spacing may be defined as the distance "P2" between the centers of adjacent projections 1206.

In some cases, each tab 1206 of the plurality of tabs 1206 is surrounded by six tabs 1206. In addition, each projection 1206 defines a diameter "D1". The diameter "D1" of each projection 1206 may have small variations due to shape imperfections of each projection 1206. Each projection 1206 is generally spherical in shape due to minor variations. Further, the projections 1206 may have a nearly similar diameter. In other words, the variation in diameter "D1" across the projection 1206 may be small. For example, the diameter "D1" varies across the projection 1206 by a small percentage. In one example, the diameter "D1" of each projection 1206 has a variation of less than or equal to 5%. Variations in diameter "D1" across the projection 1206 may be minimized. The diameter "D1" of each projection 1206 may also have a small value. The smaller protrusions 1206 have a higher packing density and therefore have less surface reflection. In addition, the space between adjacent protrusions 1206 may also be minimized.

In some examples, the diameter "D1" of the protrusion 1206 is approximately between 0.8 μm and 3 μm to achieve low surface reflection. This is because the protrusions 1206 having a smaller diameter (such as less than 1 μm) exhibit characteristics similar to those of the anti-reflection film having a plurality of coatings. In this case, the intermediate visible wavelength has the lowest surface reflection, and the low and high visible wavelength reflections have surface reflections that are greater than the surface reflection of the intermediate visible wavelength. Further, the reflection spectrum curve of such an antireflection film is concave. It should be further noted that the ideal diameter "D1" of the protrusion 1206 that provides optimal surface reflection is approximately between 1.5 μm and 2 μm.

In one embodiment, the average diameter "Db" of the protrusions 1206 is greater than or equal to 1 μm and less than or equal to 30 μm. The average diameter "Db" may be selected based on the desired anti-reflection characteristics of the anti-reflection film 1200. The average diameter "Db" may be equal to the average of the diameters "D1" of the projections 1206. For the anti-reflection film 1200, the average diameter "Db" is used due to the variation in diameter "D1" across the protrusion 1206.

In one embodiment, the standard deviation of the projections 1206 is 70% or less of the average diameter "Db" of the projections 1206. In other words, when the protrusions 1206 are implemented as particles, the standard deviation of the particle diameters is 70% or less of the average diameter of the particles. It should be noted that the principle of operation of the anti-reflection film 1200 is similar to that of the anti-reflection film 100 explained with respect to fig. 2. It should further be noted that the values defined by the anti-reflection film 1200 are calculated using equation (I) above, and the calculation and description of the variables of the anti-reflection film 1200 are similar to those of the anti-reflection film 100 discussed above.

Fig. 12 and 13 will now be described in detail. It should be noted that fig. 12 and 13 are explained using two types of samples. The sample of example 1 provided in table 1 has a single bead coating and the sample of example 2 provided in table 1 has a double bead coating.

It should be noted that the samples of examples 1 and 2 above include 60% by weight of "S1" particles, 24% by weight of hexanediol diacrylate (SR238B), 16% by weight of dipentaerythritol pentaacrylate (SR399), and 30% by weight of solids. SR238B and SR399 are monomers manufactured by Sartomer company. SR238B is a low viscosity, fast curing monomer with low volatility, hydrophobic backbone and good solubility useful for free radical polymerization. SR399 has abrasion resistance and flexibility, hardness and fast curing response, and is suitable for ultraviolet and electron beam curing. It is a low skin irritation monomer. In this example, the samples of examples 1 and 2 included 300 grams of "S1" particles, 120 grams of SR238B, 80 grams of SR399, 994 grams of DOWANOL^TMPM (Dow chemical), 174 grams isopropyl alcohol (IPA), 2 grams IR184, and 2.1 grams

Rad 2250. In addition, IPA is a colorless, flammable compound with a strong odor. In addition to this, the present invention is,

rad2250 is a radiation-curable substrate wetting, flow and slip additive. It is aA transparent liquid silicone polyether acrylate. The above components were ultrasonically mixed for 15 minutes to form samples of example 1 and example 2.

Fig. 12 is an exemplary graph 1402 illustrating specular reflection data for some samples. The wavelength in nm is marked on the X-axis and the reflection in percent is marked on the Y-axis. Graph 1402 is prepared by plotting the results of two different samples. More specifically, the pattern 1404 is generated by drawing dots corresponding to embodiment 1, and the pattern 1406 is generated by drawing dots corresponding to embodiment 2. After adjusting the coating gap, the single layer and the double layer on each sample of example 1 and example 2 were provided by a die coating method. Graph 1402 shows that example 2 with a bilayer has fewer dimples (i.e., regions without beads) than example 1 with a monolayer. Further, example 2 has a better low reflectance than example 1. The term "indentation" as referred to herein may be defined as a flat area without the protrusions 106, 406, 1206, 1604.

Fig. 13 is an exemplary graph 1502 illustrating total reflection data for some samples. The wavelength in nm is marked on the X-axis and the reflection in percent is marked on the Y-axis. Graph 1502 is prepared by plotting the results of two different samples. More specifically, the pattern 1504 is generated by drawing dots corresponding to embodiment 1, and the pattern 1506 is generated by drawing dots corresponding to embodiment 2. Graph 1502 shows that example 2 with a bilayer has fewer dimples, i.e., areas without beads, than example 1 with a monolayer. Further, example 2 has a better low reflectance than example 1.

Further, for the samples given above, diffuse reflectance (total reflectance) data of the samples was measured by a spectrophotometer with an integrated sphere in U4100 manufactured by Hitachi High Tech Science Corporation. In addition, the specular reflectance data of the sample was measured by a spectrophotometer with 12 degree incidence in UV-3100PC manufactured by Shimadzu corporation. Further, the average of the measured specular reflectance data was calculated from a wavelength range of 400nm to about 800 nm.

Fig. 14 shows an exemplary film sample 1602 including a microreplicated structure. In some examples, the plurality of protrusions 1604 of the film sample 1602 may be arranged in a perfect hexagonal pattern. As shown, the film sample 1602 is made by microreplication, so each of the protrusions 1604 are arranged regularly. Further, each protrusion 1604 is surrounded by six identical protrusions 1604 arranged at the same distance from the protrusion 1604. One such example of a microreplicated film sample is example 6 provided in table 1, the specular response of which is shown in fig. 8. In one embodiment, protrusions 1604 are integral with substrate 1603 (shown in fig. 15) of film sample 1602. It should be noted that in film sample 1602, the value of NN1/NN6 was always 1. More specifically, the value of NN6/NN1 is equal to the union of protrusions 1604 arranged in a perfect hexagonal pattern, such as a hexagonal close-packed arrangement. It should be noted that the values of NN1 and NN6 referred to herein are calculated in a manner similar to that described with respect to fig. 3. More specifically, distances NN1 and NN6 are calculated with reference to the surrounding six projections of projection 1604.

Referring now to fig. 15, a cross-sectional view of an anti-reflective film sample 1602 is shown. In this embodiment, the protrusion 1604 is implemented as a microreplicated structure formed on the substrate 1603. In one embodiment, the protrusion 1604 may be integral with the substrate 1603. For example, the protrusions 1604 may be formed on the substrate 1603 by microreplication. More specifically, the upper surface of substrate 1603 is shaped such that substrate 1603 includes protrusions 1604. In such embodiments, the protrusions 1604 and the substrate 1603 may be made of the same material. Microreplicated structures are created using a mold. It should be noted that the mold itself includes the microreplicated structure. More specifically, in order to manufacture the anti-reflection film sample 1602 having a microreplicated structure, a resin (or solvent) is coated on a mold. After the resin dries or cures, a resin layer having a microreplicated structure of the substrate 1603 and the protrusions 1604 is formed. The resin layer thus formed is then taken out of the mold.

Fig. 16 is an exemplary graph 1802 showing the bead coverage of anti-reflection film samples designated as examples 1 to 10 as mentioned in table 1 given above. Samples are marked on the X-axis and percent coverage is marked on the Y-axis. The bead coverage of the samples was measured from the AFM height map of each sample. For these measurements, the perimeter of each bead of the corresponding sample is defined as the point around the bead where the g-curvature or t-curvature is zero. The term "g-curvature" referred to herein is defined as curvature in the direction of the gradient vector, and the term "t-curvature" is defined as curvature in the direction transverse to the gradient vector. Further, the curvature is defined as the peak being positive and the valley being negative.

Unless otherwise indicated, all numbers expressing feature sizes, quantities, and physical characteristics used in the specification and claims are to be understood as being modified by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. Further, the above-described antireflection films 100, 400, 1200, 1602 are implemented as low-thickness films that are easy to design and manufacture. In addition, the anti-reflective films 100, 400, 1200, 1602 are cost effective compared to anti-reflective films having a variety of coatings currently on the market. The anti-reflective films 100, 400, 1200, 1602 also exhibit lower surface reflection characteristics than the anti-reflective films currently available on the market.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Accordingly, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims (5)

1. An antireflection film comprising:

a plurality of spherical protrusions, wherein the protrusions have an average diameter greater than or equal to 1 μ ι η and less than or equal to 30 μ ι η;

wherein the protrusions form a monolayer or bilayer, and wherein the protrusions occupy at least 35% of the area of the monolayer or bilayer;

wherein a value defined by the following formula is greater than or equal to 1 and less than or equal to 1.7:

value NN6/NN1

Where NN1 is the distance between one protrusion and the other protrusion closest to the protrusion, and NN6 is the distance between the protrusion and the sixth other protrusion closest to the protrusion.

2. The anti-reflective film of claim 1, wherein the total reflectance of the anti-reflective film is 5% or less.

3. The antireflection film of claim 1, further comprising:

a substrate;

a transparent resin layer bonding a single layer or a double layer of a plurality of protrusions to the substrate; and

including the protrusions of the particles.

4. The antireflection film of claim 3, wherein a standard deviation of the particles is 70% or less of an average diameter of the particles.

5. The anti-reflection film of claim 1, wherein the protrusions are microreplicated structures.

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