Viewing angle control film and display device including the same

Abstract

The present disclosure relates to a viewing angle control film and a display device including the same, and more particularly, according to one aspect of the present disclosure, the viewing angle control film includes a first base material, a first electrode disposed on the first base material, a transparent resin layer disposed on the first electrode and having a plurality of accommodation units, a second electrode disposed on the transparent resin layer, and a second base material disposed on the second electrode, wherein an ink including charged hollow carbon black and a solvent is accommodated in each of the plurality of accommodation units. Accordingly, according to the present disclosure, the viewing angle control film has excellent dispersion stability, and particle sedimentation due to gravity is inhibited, improving driving characteristics.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2021-0113528, filed with the Korean Intellectual Property Office on August 26, 2021, the disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to a viewing angle control film and a display device including the viewing angle control film, and more specifically, to a viewing angle control film having a high switching speed, excellent performance and driving stability in a wide viewing angle mode and a narrow viewing angle mode, and a display device including the viewing angle control film. Background Technology

[0004] With the growing demand for personal privacy protection, various related products are being developed across different sectors. Among products that ensure personal privacy, the demand for viewing angle control devices attached to various displays such as mobile phones, tablets, monitors, or vehicle displays to block lateral light transmission and narrow the viewing angle is increasing year by year.

[0005] In this regard, existing technologies have employed film-type viewing angle control films that alternately form light-transmitting regions through which light is transmitted and light-shielding regions that block light in specific directions. These films include transmissive regions and light-shielding regions disposed between them to block or absorb light. The light-shielding regions contain black pigment. In light incident from below, light with an incident angle equal to or greater than a predetermined angle is absorbed or blocked by the repeatedly formed light-shielding regions, preventing light from passing through the viewing angle control film. Consequently, at viewing angles equal to or greater than the predetermined angle, light transmittance is significantly reduced, making the screen invisible. However, a drawback of existing viewing angle control films is that the viewing angle cannot be restored to its current state without removing the film, thus requiring film removal.

[0006] Recently, in order to solve this inconvenience, a viewing angle control membrane has been developed that selectively switches between wide-viewing-angle and narrow-viewing-angle modes based on an externally applied electrical signal without the need for an attached / separated membrane.

[0007] However, switchable viewing angle control films suffer from the following problems: reduced dispersion of black particles in the ink and decreased driving characteristics due to particle sedimentation, as well as slow switching speed between wide and narrow viewing angle modes. Furthermore, when using high-density solvents or adding additional anti-settling agents to improve particle sedimentation, the ink viscosity increases, thus slowing down the driving speed. Summary of the Invention

[0008] One objective of this disclosure is to provide a view control membrane that reduces the density difference between the solvent and the particles to achieve excellent dispersion stability and suppresses particle sedimentation to improve driving characteristics.

[0009] In addition, another objective is to provide a viewing angle control film that has excellent dual stability and uses inks with low viscosity to achieve excellent switching speed between wide and narrow viewing angle modes.

[0010] Furthermore, one object of this disclosure is to provide a viewing angle control membrane with excellent performance and driving stability.

[0011] The purpose of this disclosure is not limited to the above-mentioned purposes, and other purposes not mentioned above can be clearly understood by those skilled in the art from the following description.

[0012] According to one aspect of this disclosure, a viewing angle control film includes: a first substrate material; a first electrode disposed on the first substrate material; a transparent resin layer disposed on the first electrode and having a plurality of containment units; a second electrode disposed on the transparent resin layer; and a second substrate material disposed on the second electrode, wherein an ink comprising charged hollow carbon black and a solvent is contained in each of the plurality of containment units.

[0013] According to one aspect of this disclosure, a display device includes: a display panel; and a viewing angle control film disposed above or below the display panel.

[0014] Further details of the exemplary embodiments are included in the detailed description and the accompanying drawings.

[0015] According to this disclosure, in the viewing angle control film, an ink comprising charged hollow carbon black and a solvent is contained in each of a plurality of containment units. The density difference between the charged hollow carbon black and the solvent is significantly reduced to suppress particle sedimentation. Therefore, according to this disclosure, the viewing angle control film exhibits excellent dispersion stability and suppresses particle sedimentation due to gravity to improve driving characteristics.

[0016] According to this disclosure, even if the viewing angle control film includes a small amount of hollow carbon black, it has excellent shading efficiency in narrow viewing angle mode, and the viscosity of the ink is reduced to improve driving characteristics and driving speed.

[0017] Therefore, the display device including the viewing angle control film according to the present disclosure has excellent switching speed between wide viewing angle mode and narrow viewing angle mode and excellent driving performance.

[0018] The effects of this disclosure are not limited to those illustrated above; this specification includes a variety of other effects. Attached Figure Description

[0019] The above and other aspects, features, and other advantages of this disclosure will be more clearly understood through the following detailed embodiments, taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1 This is a schematic cross-sectional view of the control membrane according to exemplary embodiments of the present disclosure;

[0021] Figure 2 This is an enlarged view of the control membrane according to exemplary embodiments of the present disclosure;

[0022] Figure 3 This is a schematic cross-sectional view of hollow carbon black;

[0023] Figure 4A This is a schematic cross-sectional view of the view control membrane in narrow view mode according to an exemplary embodiment of the present disclosure;

[0024] Figure 4B This is a schematic cross-sectional view of the view control membrane in wide-view mode according to an exemplary embodiment of the present disclosure;

[0025] Figure 5 This is a schematic cross-sectional view of the view control membrane according to another exemplary embodiment of the present disclosure;

[0026] Figure 6 This is a schematic cross-sectional view of a view control membrane according to another exemplary embodiment of this disclosure;

[0027] Figure 7 This is a schematic cross-sectional view of an organic light-emitting display device according to an exemplary embodiment of the present disclosure;

[0028] Figure 8 This is a schematic cross-sectional view of a liquid crystal display device according to an exemplary embodiment of the present disclosure;

[0029] Figure 9A This is a graph showing the density difference between particles and solvent and the sedimentation velocity as a function of the average particle size of hollow carbon black.

[0030] Figure 9B This is a graph showing the density difference between particles and solvent and the sedimentation velocity as a function of the average particle size of carbon black.

[0031] Figure 10 This is a graph showing the change in brightness of the film over time according to the viewing angle control of Example 2 and Comparative Example 2;

[0032] Figure 11A This is a graph showing the brightness variation over time in the narrow viewing angle mode of the viewing angle control film according to Example 2 and Comparative Example 2;

[0033] Figure 11BThis is a graph showing the brightness variation over time in the wide viewing angle mode of the viewing angle control film according to Example 2 and Comparative Example 2;

[0034] Figure 12A This is a photograph taken from the front when the viewing angle control film according to Example 2 is in narrow viewing angle mode;

[0035] Figure 12B This is a photograph observed from a 30° side surface when the viewing angle control film according to Example 2 is in narrow viewing angle mode;

[0036] Figure 13A This is a photograph taken from the front when the viewing angle control film of Comparative Example 2 is in narrow viewing angle mode;

[0037] Figure 13B These are photographs taken from the 30° side surface of the film when the viewing angle control film of Comparative Example 2 is in narrow viewing angle mode; and

[0038] Figure 14 This is a graph showing the brightness distribution of the organic light-emitting display device according to Example 2 and the reference example as a function of viewing angle. Detailed Implementation

[0039] The advantages and features of this disclosure and its implementation methods will become clear from the following exemplary embodiments described in detail with reference to the accompanying drawings. However, this disclosure is not limited to the exemplary embodiments disclosed herein, but will be implemented in different forms. These embodiments are provided by way of example only so that those skilled in the art can fully understand the disclosure and scope of this disclosure. Therefore, this disclosure is limited only by the scope of the appended claims.

[0040] The shapes, dimensions, ratios, angles, quantities, etc., shown in the accompanying drawings used to describe exemplary embodiments of this disclosure are merely examples, and this disclosure is not limited thereto. Throughout the specification, the same reference numerals generally refer to the same elements. Furthermore, in the following description of this disclosure, detailed descriptions of known related technologies may be omitted to avoid unnecessarily obscuring the subject matter of this disclosure. Terms such as “comprising,” “having,” and “including” as used herein are generally intended to allow for the addition of additional components, unless these terms are used in conjunction with the term “only.” Unless otherwise stated, any reference to the singular may include the plural.

[0041] Even without explicit explanation, components are interpreted as including the normal tolerance range.

[0042] When using terms such as “on top of,” “above,” “below,” and “near” to describe the positional relationship between two components, one or more components may be located between the two components unless the terms “immediately adjacent” or “directly” are used.

[0043] When one element or layer is placed "on" another element or layer, another layer or element can be placed on or directly between the other element.

[0044] Although the terms "first," "second," etc., are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from other components. Therefore, the first component mentioned below can be the second component in the technical concept of this disclosure.

[0045] Throughout the specification, the same reference numerals generally refer to the same elements.

[0046] The dimensions and thicknesses of each component shown in the accompanying drawings are for ease of description and this disclosure is not limited to the dimensions and thicknesses of the components shown.

[0047] Features of the various embodiments of this disclosure may be combined or integrated with each other in part or in whole, and may be technically related and operable in various ways, and the embodiments may be implemented independently of each other or in relation to each other.

[0048] Unless otherwise stated herein, the density is a value measured at 15 to 20°C.

[0049] Unless otherwise stated herein, the average particle size refers to the particle size D50 corresponding to 50% of the cumulative particle size distribution.

[0050] In the following, a view control film and a display device according to exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0051] Figure 1 This is a schematic cross-sectional view of the view control membrane according to an exemplary embodiment of the present disclosure. Figure 2 This is an enlarged view of the view control membrane according to an exemplary embodiment of the present disclosure.

[0052] The viewing angle control film according to exemplary embodiments of the present disclosure is applied to an organic light-emitting display device or a liquid crystal display device. When no electric field is formed, the viewing angle control film operates in a wide viewing angle mode to transmit light incident from below at various angles, thereby allowing the image displayed on the display device to be viewed not only from the front surface but also from the side. Conversely, when no electric field is formed, the viewing angle control film absorbs light incident from below with an incident angle equal to or greater than a predetermined angle. Therefore, the viewing angle control film operates in a narrow viewing angle mode to allow the user to observe the image displayed on the display device from the front surface of the display device or only within a predetermined narrow angle range.

[0053] First, refer to Figure 1 and Figure 2The viewing angle control film 100 according to an exemplary embodiment of the present disclosure includes a first substrate material 110a, a first electrode 120a, an adhesive layer ADH, a transparent resin layer 130, a plurality of receiving units 140, an ink 150, a second electrode 120b, and a second substrate material 110b.

[0054] A first substrate material 110a protects the first electrode 120a and the transparent resin layer 130. The first substrate material 110a may be formed of a transparent insulating material. For example, the first substrate material 110a may be formed of one or more polymers selected from cyclic olefin polymers, cyclic olefin copolymers, cellulose triacetate, polycarbonate, polyethylene terephthalate, and polyimide. Ideally, for example, the first substrate material 110a may be formed of a material selected from cyclic olefin polymers and cyclic olefin copolymers. In this case, the optical properties of the viewing angle control film are more superior.

[0055] For example, the thickness of the first substrate material 110a may be 50 μm to 200 μm or 100 μm to 150 μm, but is not limited thereto.

[0056] The first electrode 120a is disposed on the first substrate material 110a. The first electrode 120a may be formed of a transparent conductive material to transmit light incident from below. For example, the transparent conductive material may be one or more selected from indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), and aluminum zinc oxide (AZO), but is not limited thereto.

[0057] The first electrode 120a may be formed on the front surface of the first substrate material 110a, and if necessary, the first electrode 120a may be selectively patterned to overlap with the plurality of receiving units 140.

[0058] For example, the thickness of the first electrode 120a may be 0.1 μm to 10 μm, 0.1 μm to 2 μm, or 0.1 μm to 0.5 μm, but is not limited thereto.

[0059] A transparent resin layer 130 is disposed on the first electrode 120a. The transparent resin layer 130 may be formed of a transparent insulating resin that transmits light incident from the lower part of the viewing angle control film 100. For example, the transparent resin layer 130 may include one or more selected from acrylic resin, polycarbonate, polyethylene terephthalate, cellulose triacetate resin, polyethylene, and polypropylene.

[0060] Specifically, for example, the transparent resin layer 130 may comprise an acrylic resin formed by curing a resin composition comprising a UV-curable compound, such as a polyurethane acrylate compound or an epoxy acrylate compound. Specifically, acrylic resins formed from polyurethane acrylate compounds have advantages such as excellent curability, high transparency, and excellent adhesion. Specifically, for example, the transparent resin layer 130 may be formed by photopolymerization of a resin composition comprising a polyurethane acrylate compound, a photoinitiator, and a release agent. In this case, to increase the curing speed and improve physical properties such as adhesion, two or more polyurethane acrylate compounds with different molecular weights may be mixed.

[0061] There are no particular limitations on photoinitiators if they are commonly used in the art to manufacture transparent resins. For example, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide or acylphosphine oxide can be used as photoinitiators, but are not limited thereto.

[0062] The transparent resin layer 130 may further include a surfactant. The surfactant may be one or more selected from tricresyl phosphate and tributyl phosphate. In order to drive the viewing angle control film 100, an electric field is formed by applying a voltage to the first electrode 120a and the second electrode 120b, such that the surfactant is dispersed in the transparent resin layer 130 to facilitate the formation of the electric field.

[0063] The transparent resin layer 130 may further include a release agent. The transparent resin layer 130 includes a plurality of receiving units 140 formed by physical processes such as master molding, imprinting, or photolithography. The release agent facilitates the separation of the structure used to form the pattern (e.g., a mold for forming the plurality of receiving units 140) from the transparent resin layer 130. For example, the release agent uses silicone-based, polyvinyl-based, or paraffin-based materials commonly used in the art without reducing transparency.

[0064] For example, the thickness of the transparent resin layer 130 can be from 80 μm to 200 μm, but is not limited to this.

[0065] The transparent resin layer 130 includes a plurality of receiving units 140. Each of the plurality of receiving units 140 is a space for receiving ink 150 that absorbs light incident from the outside. The plurality of receiving units 140 are grooves formed in the transparent resin layer 130 and the plurality of receiving units 140 are formed on the first electrode 120a opposite to the second electrode 120b.

[0066] Each of the plurality of receiving units 140 is configured to be spaced apart from each other at a predetermined interval along a first direction (x-axis direction) perpendicular to the thickness direction (z-axis direction) of the transparent resin layer 130.

[0067] Each of the plurality of receiving units 140 extends along a second direction (y-axis direction) perpendicular to the thickness direction (z-axis direction) and the first direction (x-axis direction). That is, each of the plurality of receiving units 140 extends from any one corner of the first electrode 120a to another corner parallel to that corner, thereby forming a strip structure on the first electrode 120a.

[0068] Each of the plurality of receiving units 140 comprises a lower surface 141, an upper surface 142, a first connecting unit 143a, and a second connecting unit 143b. Specifically, each of the plurality of receiving units 140 includes a lower surface 141 opposite to the first electrode 120a and an upper surface 142 opposite to the lower surface 141. Furthermore, each of the plurality of receiving units 140 includes a first connecting unit 143a connecting one end of the lower surface 141 and one end of the corresponding upper surface 142, and a second connecting unit 143b connecting the other end of the lower surface 141 and the other end of the corresponding upper surface 142.

[0069] Each of the plurality of receiving units 140 may be configured such that its width decreases from the first electrode 120a toward the second electrode 120b. That is, the width W1 of the lower surface 141 of each of the plurality of receiving units 140 is greater than the width W2 of the upper surface 142. In the figures, although the cross-sectional shape of each of the plurality of receiving units 140 is shown to be trapezoidal, this is only an example and is not a limitation.

[0070] The upper surface 142 of each of the plurality of receiving units 140 is spaced apart from the second electrode 120b. That is, each of the plurality of receiving units 140 does not penetrate the transparent resin layer 130 in the thickness direction (z-axis direction) of the transparent resin layer 130. When the plurality of receiving units 140 are formed with a hole structure that penetrates the transparent resin layer 130, if the liquid ink 150 fills the receiving unit 140, it may cause problems such as leakage, which will reduce productivity and lead to defects. In order to suppress problems in the process, the upper surface 142 of the plurality of receiving units 140 is spaced apart from the second electrode 120b and does not contact it, and the transparent resin layer 130 exists in the space between the upper surface 142 and the second electrode 120b.

[0071] The ink 150 includes charged hollow carbon black 151 and solvent 152. The charged hollow carbon black 151 can absorb light incident from the outside. The solvent 152 disperses the charged hollow carbon black 151, which is a solid, in a plurality of containment units 140.

[0072] For example, solvent 152 may be one or more selected from halogenated hydrocarbon solvents, isoparaffin solvents, and ether solvents.

[0073] For example, the halogenated hydrocarbon solvent can be a fully or partially halogenated hydrocarbon. For example, the halogenated hydrocarbon solvent can include one or more selected from halogenated hydrocarbons 0.8, 1.8, 4.2 and 6.3, 3M LLC.FC-72, FC-74 and FC-70, Milo FCL1031 and Solvay HT55.

[0074] For example, isoparaffin solvents may include one or more of Isopar G, Isopar L, Isopar C, Isopar E, Isopar M and Isopar H selected from ExxonMobil, but are not limited thereto.

[0075] For example, the ether solvent may include one or more selected from diethylene glycol dimethyl ether, propylene glycol methyl ether and propylene glycol methyl ether acetate, but is not limited thereto.

[0076] Solvent 152 has different densities and dielectric constants depending on its type, and is appropriately selected according to the desired properties. Furthermore, solvent 152 uses a single material, and two or more materials can be mixed if necessary to control the density or dielectric constant of ink 150.

[0077] Furthermore, considering process stability, solvents with an ignition point below 60 degrees Celsius can be preferably used as solvent 152.

[0078] Simultaneously, solvent 152 is preferably used after removing moisture with a moisture-removing agent. Moisture in solvent 152 promotes particle aggregation, increasing the viscosity of ink 150. As the viscosity of ink 150 increases, the migration rate of particles (i.e., charged hollow carbon black 151) decreases, thus deteriorating driving characteristics and potentially reducing the switching speed between wide-viewing-angle and narrow-viewing-angle modes. Therefore, it is preferable to use moisture-removing agents commonly used in the art, such as zeolite, magnesium hydroxide, and porous silica, to remove as much moisture as possible from solvent 152.

[0079] Figure 3 This is a schematic cross-sectional view of charged hollow carbon black. (Refer to...) Figure 3 The charged hollow carbon black 151 includes a hollow portion 151a and a shell 151b. The hollow portion 151a is the core part of the particle and is a generally hollow body. The shell 151b includes carbon black and is formed to surround the hollow portion 151a. The shell 151b is formed to have a porous structure or a non-porous structure.

[0080] The charged hollow carbon black 151 includes a hollow portion 151a, which makes its density lower than that of ordinary carbon black particles that do not include the hollow portion 151a. Therefore, the charged hollow carbon black 151 will not settle due to gravity and will remain stably dispersed in the ink 150.

[0081] The settling velocity of the particles can be calculated using the following equation 1.

[0082] [Equation 1]

[0083]

[0084] Here, ν is the settling velocity of the particle, a is the radius of the particle, p2 is the density of the particle, p1 is the density of the particle, g is the acceleration due to gravity, and n is the viscosity of the solvent.

[0085] As shown in Equation 1, as the difference between the particles and the solvent (p2-p1) increases, the settling velocity ν of the particles increases. Therefore, in order to uniformly disperse the charged particles in the multiple containment units 140 without causing the charged particles to settle, the charged particles and the solvent need to have substantially the same density.

[0086] The density of isoparaffinic solvents and haloalkanes, commonly used solvents in this field, is 0.6 g / cm³. 3 Up to 1.2 g / cm 3 However, the density of carbon black using existing technology is 1.4 g / m³. 3 The density of carbon black is higher than that of the solvent. Therefore, existing inks suffer from difficulties in uniformly dispersing carbon black due to the density difference between the carbon black and the solvent, and the carbon black settles due to gravity. Furthermore, the bistability of the viewing angle control film is reduced, and improvements in driving speed and properties are limited.

[0087] The charged hollow carbon black 151 disclosed herein includes a hollow portion 151a, resulting in a density lower than that of prior art carbon blacks. For example, the density of the charged hollow carbon black 151 can be 0.60 g / cm³. 3 Up to 0.90 g / cm 3 Or 0.70g / cm 3 Up to 0.80 g / cm 3 Therefore, the density difference with the solvent is significantly reduced, resulting in excellent particle dispersion stability and suppressed sedimentation. Consequently, the charged hollow carbon black 151 is uniformly dispersed in the solvent 152, thereby significantly improving the uniformity of the ink 150. Furthermore, the dual stability of the viewing angle control film 100 is improved, the driving characteristics are enhanced, and the switching speed between wide and narrow viewing angle modes is excellent.

[0088] The density of the charged hollow carbon black 151 can vary depending on the size (i.e., volume percentage) of the hollow portion 151a. For example, the volume percentage of the hollow portion 151a can be from 50% to 90% or from 70% to 90% volume. Within this range, the density difference with the solvent 152 is small, and the effect of suppressing particle sedimentation is particularly excellent.

[0089] The BET surface area of ​​charged hollow carbon black 151 can be 500 m². 2 / g to 1500m 2 / g or 900m 2 / g to 1500m 2 / g. Within this range, the density difference between charged hollow carbon black 151 and solvent 152 decreases, thereby suppressing particle sedimentation.

[0090] The average particle size of the charged hollow carbon black 151 can be from 100 nm to 500 nm. More preferably, the average particle size of the charged hollow carbon black 151 can be from 140 nm to 250 nm or from 140 nm to 180 nm. Within this range, the ink 150 exhibits excellent dispersion stability and slow sedimentation rate. When the average particle size is too small, the dispersion stability of the charged hollow carbon black 151 may decrease due to the interaction between particles. Furthermore, due to the interaction between particles, particle aggregation may occur, which may promote sedimentation. As shown in Equation 1, the sedimentation rate v of the particles increases with the increase of the particle radius a. Therefore, when the average particle size of the charged hollow carbon black 151 is too large, there may be a problem that the charged hollow carbon black 151 settles in the ink 150 due to gravity.

[0091] The charged hollow carbon black 151 carries either a positive or negative charge. Therefore, when a voltage is applied to the first electrode 120a and the second electrode 120b, the charged hollow carbon black 151, uniformly dispersed in the solvent 152, accumulates near the first electrode 120a or the second electrode 120b due to the electric field formed between them. A detailed description follows.

[0092] For example, charged hollow carbon black 151 carries a negative charge. Specifically, the negatively charged hollow carbon black 151 can be made from materials selected from carboxylate (-COO) groups. - ), sulfonate (-SO3-) and sulfate (SO4-) 2- Hollow carbon black with one or more functional groups in ) is surface-modified. For example, hollow carbon black modified with carboxylate is obtained by a simple process of adding hollow carbon black to nitric acid and / or sulfuric acid, reacting the hollow carbon black at a relatively low temperature of about 100°C, and then dispersing the hollow carbon black in solvent 152. The charged hollow carbon black 151 obtained as described above has a high surface charge. The charged hollow carbon black 151 has a high surface charge, which allows it to move more quickly through an electric field, thus improving its bistability and enhancing the driving characteristics and stability of the viewing angle control film 100.

[0093] For example, based on the total weight of ink 150, the content of charged hollow carbon black 151 is from 0.1% to 5% by weight. When the content of charged hollow carbon black 151 is too low, the light absorption effect is reduced, and when the content is too high, the light transmittance in the wide viewing angle mode is reduced.

[0094] Ink 150 may further include a dispersant. A dispersant having basic functional groups may be used. For example, the dispersant may be polyisobutylene succinimide represented by the following molecular formula 1.

[0095] [Molecular Formula 1]

[0096]

[0097] In formula 1, n is an integer from 5 to 500.

[0098] The amino groups of the dispersant represented by Formula 1 react with functional groups bonded to the surface of the charged hollow carbon black 151. The dispersant represented by Formula 1 forms a bonded layer to the surface of the charged hollow carbon black 151, thus surrounding the surface of the charged hollow carbon black 151. The dispersant represented by Formula 1 has a long chain length, which allows the dispersant to surround the surface of the charged hollow carbon black 151, thereby acting as a protective layer to inhibit particle aggregation. Furthermore, the dispersant represented by Formula 1 enables the negatively charged hollow carbon black 151 to stably maintain its charged state. This generates a repulsive force between particles to minimize particle aggregation. Therefore, the dispersibility of the charged hollow carbon black 151 is improved, the dispersion stability of the ink 150 is improved, thereby improving the driving characteristics of the viewing angle control film 100.

[0099] For example, based on the total weight of ink 150, the content of dispersant can be from 0.1% to 5% by weight. When the content of dispersant is too low, the improvement in dispersion stability may not be significant. Dispersants have large molecular weights, so adding too much dispersant may increase the viscosity of ink 150. When the viscosity of ink 150 increases, the charged hollow carbon black 151 is less likely to move, which may reduce the driving characteristics of the viewing angle control film 100.

[0100] The ink 150 may further include a surfactant. For example, the surfactant may be a phosphate compound, but is not limited thereto. Specifically, for example, the surfactant may be selected from tricresyl phosphate and tributyl phosphate, but is not limited thereto. The surfactant increases the dielectric constant of the ink 150 to improve the response speed of the viewing angle control film 100.

[0101] The second electrode 120b is disposed on the transparent resin layer 130. The second electrode 120b is substantially the same as the first electrode 120a described above, except that the second electrode 120b is disposed above the transparent resin layer 130. Furthermore, a second substrate material 110b is disposed on the second electrode 120b. The second substrate material 110b is substantially the same as the first substrate material 110a described above, except that the second substrate material 110b is disposed on the second electrode 120b. Therefore, repeated descriptions will be omitted.

[0102] An adhesive layer ADH is disposed between the transparent resin layer 130 and the first electrode 120a. For example, the viewing angle control film 100 is manufactured by: manufacturing a first assembly consisting of a first substrate material 110a and a first electrode 120a, and manufacturing a second assembly consisting of a second substrate material 110b, a second electrode 120b, and ink 150 contained in a plurality of receiving units 140; and then bonding the first assembly to the second assembly. In this case, after the ink 150 is injected into the plurality of receiving units 140, the adhesive layer ADH is used to bond the first assembly to the second assembly. However, this is not a limitation; the adhesive layer ADH may be disposed between the transparent resin layer 130 and the second electrode 120b, or the adhesive layer ADH may be omitted depending on the manufacturing process or structure of the viewing angle control film 100.

[0103] For example, the thickness of the adhesive layer ADH can be from 1 μm to 100 μm, but is not limited to this.

[0104] For example, the adhesive layer ADH can be formed from materials selected from optically transparent adhesives (OCA), optically transparent resins (OCR), or pressure-sensitive adhesives (PSA), but is not limited thereto.

[0105] In the following text, reference will be made to Figures 4A to 4B A more detailed description of the wide-view mode and narrow-view mode.

[0106] Figure 4A This is a schematic cross-sectional view of the view control membrane in narrow view mode according to an exemplary embodiment of the present disclosure. Figure 4B This is a schematic cross-sectional view of the view control membrane in wide-view mode according to an exemplary embodiment of the present disclosure.

[0107] Reference Figure 4AWhen no electric field is formed between the first electrode 120a and the second electrode 120b, the charged hollow carbon black 151 is uniformly dispersed in the solvent 152 and randomly distributed in the plurality of containment units 140. Since the charged hollow carbon black 151 is randomly distributed in the plurality of containment units 140 as described above, the plurality of containment units 140 absorb the incident light. Therefore, light incident at a predetermined angle or greater is blocked by the plurality of containment units 140. That is, in the light incident from the lower part of the viewing angle control film 100a, light incident at a predetermined angle or greater relative to the front surface (z-axis) is absorbed by the charged hollow carbon black 151 dispersed in the plurality of containment units 140. Therefore, light is not emitted to the outside of the viewing angle control film 100a. For example, in the light incident from the lower part of the viewing angle control film 100a, light incident at a first angle θ1 onto the front surface (z-axis) is output to the outside of the viewing angle control film 100a. However, light incident at a second angle θ2 greater than the first angle is not emitted to the outside. Therefore, light incident at a predetermined angle or greater is blocked, thus enabling operation in a narrow viewing angle mode.

[0108] Reference Figure 4B When a voltage is applied between the first electrode 120a and the second electrode 120b to form an electric field, the charged hollow carbon black 151, randomly dispersed in the plurality of containment units 140, moves toward the electrodes through the electric field. That is, according to the charge, the charged hollow carbon black 151 moves toward the electrode to which the opposite voltage is applied.

[0109] For example, when the charged hollow carbon black 151 carries a negative charge, if a negative voltage is applied to the first electrode 120a and a positive voltage is applied to the second electrode 120b, the negatively charged hollow carbon black 151 moves to the upper surface 142. The upper surface 142 is adjacent to the second electrode 120b to which the positive voltage is applied. Therefore, the charged hollow carbon black 151 is stacked from the upper surface 142 of the receiving unit 140 with a predetermined thickness. That is, in most areas except for the region adjacent to the upper surface 142 of the receiving unit 140 where the charged hollow carbon black 151 is stacked, the density of the charged hollow carbon black 151 is very low. The portion of the charged hollow carbon black 151 with very low density has high transparency. Therefore, light can pass through the low-density region of the charged hollow carbon black 151. Therefore, in the light incident from the lower part of the viewing angle control film 100b, not only is light incident at a first angle θ1 relative to the front surface (z-axis) emitted to the outside, but light incident at a second angle θ2 greater than the first angle is also emitted to the outside. Therefore, the travel angle of the light emitted to the outside of the viewing angle control film 100b is... Figure 4A The travel angle shown is increased, thus enabling operation in wide-view mode.

[0110] As another example, when the charged hollow carbon black 151 carries a negative charge, a positive voltage is applied to the first electrode 120a and a negative voltage is applied to the second electrode 120b, thereby... Figure 4B Similar wide-view mode operation. Repeated descriptions will be omitted.

[0111] The viewing angle is controlled by the width W1 of the lower surface 141 of the receiving unit 140, the width W2 of the upper surface 142, the distance D1 from the lower surface 141 to the upper surface 142 (i.e., the height of the receiving unit 140), the distances W3 and W4 between adjacent receiving units 140, and the tilt of the first connecting unit 143a and the second connecting unit 143b.

[0112] refer to Figure 2 The width W1 of the lower surface 141 can be from 5 μm to 30 μm, the width W2 of the upper surface 142 can be from 1 μm to 15 μm, and the height D1 of the receiving unit 140 can be from 70 μm to 160 μm. The distance W3 between the lower surfaces 141 of adjacent receiving units 140 is from 15 μm to 50 μm, and the distance W4 between the upper surfaces 142 is from 25 μm to 60 μm. Within this range, a wider viewing angle can be provided in wide-viewing-angle mode without reducing brightness, and in narrow-viewing-angle mode, the propagation angle of the emitted light is small enough to achieve a narrow viewing angle. Furthermore, the width W1 of the lower surface 141 is preferably formed to be greater than the width W2 of the upper surface 142. In this case, a wider viewing angle can be provided in wide-viewing-angle mode.

[0113] The angle θa formed by the first connecting unit 143a and the lower surface 141 and the angle θb formed by the second connecting unit 143b and the lower surface 141 can be between 90° and 105°. Within this range, a wide viewing angle can be provided in the wide viewing angle mode, while in the narrow viewing angle mode, the travel angle of the light emission is reduced to achieve a narrow viewing angle.

[0114] Despite Figure 1 and Figure 2 The diagram shows that the angle θa formed by the first connecting unit 143a and the lower surface 141 and the angle θb formed by the second connecting unit 143b and the lower surface 141 are equal. However, this is merely an example, and therefore the disclosure is not limited thereto. The angle θa formed by the first connecting unit 143a and the lower surface 141 and the angle θb formed by the second connecting unit 143b and the lower surface 141 may be different.

[0115] As described above, the upper surface 142 of each of the plurality of receiving units 141 is spaced apart from the second electrode 120b, and the distance D2 from the upper surface 142 to the second electrode 120b is 5 μm to 20 μm. A transparent resin layer 130 with insulating properties is formed in the space between the upper surface 142 and the second electrode 120b. Therefore, when the distance D2 is too long, the electric field strength at the same voltage will decrease, and thus the driving characteristics may be reduced.

[0116] In the viewing angle control film 100 according to an exemplary embodiment of the present disclosure, ink 150 comprising charged hollow carbon black 151 and solvent 152 is contained in a plurality of containment units 140. Therefore, the density difference between solvent 152 and charged hollow carbon black 151 is significantly reduced. Thus, the phenomenon of charged hollow carbon black 151 settling due to gravity can be minimized. Furthermore, the dispersion stability of charged hollow carbon black 151 is improved, thereby enhancing bistability. Additionally, it provides the advantage of significantly improved driving speed of the viewing angle control film 100 and significantly improved switching speed between wide-viewing-angle mode and narrow-viewing-angle mode.

[0117] Figure 5 This is a schematic cross-sectional view of a view control membrane according to another exemplary embodiment of the present disclosure.

[0118] Figure 5 The viewing angle control membrane 200 shown is Figure 1 and Figure 2 The viewing angle control film 100 shown is essentially the same, except that the first and second electrodes are patterned and the structures of the first and second substrate materials are changed. Therefore, repeated descriptions will be omitted. Although in Figure 5 The diagram shows that the first and second electrodes have patterned structures, but it is not limited to this. If necessary, only either the first or second electrode may have a patterned structure.

[0119] Reference Figure 5 Multiple patterned electrodes 220a are disposed below the adhesive layer ADH, and multiple second patterned electrodes 220b are disposed above the transparent resin layer 130.

[0120] Each of the plurality of first patterned electrodes 220a is configured to overlap with each of the plurality of receiving units 140.

[0121] Each of the plurality of first patterned electrodes 220a extends along a second direction (y-axis direction) perpendicular to the thickness direction (z-axis direction) and the first direction (x-axis direction). Therefore, each of the plurality of first patterned electrodes 220a has a line shape extending along the second direction (y-axis direction).

[0122] The first substrate material 210a can be configured to cover the surface and side surfaces of the plurality of first patterned electrodes 220a. That is, the first substrate material 210a is configured to cover the steps formed by the plurality of first patterned electrodes 220a.

[0123] Each of the plurality of second patterned electrodes 220b is configured to overlap with each of the plurality of first patterned electrodes 220a. Therefore, each of the plurality of second patterned electrodes 220b overlaps with each of the plurality of receiving units 140.

[0124] Similar to the first patterned electrode 220a, the second patterned electrode 220b has a line shape extending along a second direction (y-axis direction) perpendicular to the thickness direction (z-axis direction) and the first direction (x-axis direction).

[0125] The second substrate material 210b can be configured to cover the surface and side surfaces of the plurality of second patterned electrodes 220b. That is, the second substrate material 210b is configured to cover the steps formed by the plurality of second patterned electrodes 220b.

[0126] For example, the widths of the plurality of first electrode patterns 220a and the plurality of second electrode patterns 220b can be from 7 μm to 50 μm. However, they are not limited thereto, and the width W1 of the lower surface 141 and / or the width W2 of the upper surface 142 can be varied according to the design.

[0127] like Figure 5 As shown, when the electrodes are patterned and configured as multiple patterned electrodes 220a and multiple patterned electrodes 220b, leakage current generated in the transparent resin layer 130 and the adhesive layer ADH can be minimized. Since the leakage current is minimized, the mobility of charged hollow carbon black 151 in the multiple containment cells 140 is further improved, and the driving characteristics and mode switching speed of the viewing angle control film can be further improved.

[0128] Figure 6 This is a schematic cross-sectional view of a view control membrane according to another exemplary embodiment of the present disclosure.

[0129] Figure 6 The viewing angle control membrane 300 shown is Figure 5 The viewing angle control membrane 200 shown is essentially the same, except for the width W1 of the lower surface, the width W2 of the upper surface, the distances W3 and W4 between adjacent receiving units, and the angle θa formed by the lower and upper surfaces. Therefore, repeated descriptions will be omitted.

[0130] Reference Figure 6The angle θa formed by the lower surface 341 and the first connecting unit 343a and the angle θb formed by the lower surface 341 and the second connecting unit 343b can be different from each other. As described above, when the angle θa formed by the lower surface 341 and the first connecting unit 343a and the angle θb formed by the lower surface 341 and the second connecting unit 343b are different, the brightness on the left side relative to the front surface is different from the brightness on the right side in narrow viewing angle mode. Therefore, if necessary, the angle θa formed by the lower surface 341 and the first connecting unit 343a and the angle θb formed by the lower surface 341 and the second connecting unit 343b are different to control the brightness on the left side and the brightness on the right side.

[0131] The angle θa formed by the lower surface 341 and the first connecting unit 343a can be greater than the angle θb formed by the lower surface 341 and the second connecting unit 343b. The viewing angle control film 300 with the above structure is used in a vehicle display, specifically as an auxiliary display. Thus, during driving, the viewing angle control film 300 is driven in a narrow viewing angle mode, resulting in lower brightness in the lateral direction where the driver's seat is located, making the screen appear darker, allowing the driver to focus more on driving. However, it is not limited to this; depending on the position of the driver's seat or if necessary, the angle θb formed by the lower surface 341 and the second connecting unit 343b can be made greater than the angle θa formed by the lower surface 341 and the first connecting unit 343a.

[0132] Specifically, the angle θa formed by the lower surface 341 and the first connecting unit 343a is 96° to 106°, and the angle θb formed by the lower surface 341 and the second connecting unit 343b is 90° to 95°. In this case, in the narrow viewing angle mode, sufficiently low brightness is provided in the lateral direction where the driver's seat is located, making it impossible for the driver to see the display. Therefore, the driver can focus on driving, and the passenger in the passenger seat can view the display with high brightness.

[0133] For example, the width W1 of the lower surface 341 is 15 μm to 30 μm, and the width of the upper surface 342 is 1 μm to 8 μm, but is not limited thereto. For example, the distance W3 between the lower surfaces 340 of adjacent receiving units 341 is 15 μm to 25 μm, and the distance W4 between the upper surfaces 342 is 25 μm to 45 μm, but is not limited thereto. Within this range, in wide-viewing-angle mode, a wider viewing angle can be provided without reducing brightness, and in narrow-viewing-angle mode, the propagation angle of the emitted light is reduced to achieve a narrow viewing angle.

[0134] The viewing angle control film 100 disclosed herein is used in organic light-emitting display devices or liquid crystal display devices.

[0135] Figure 7This is a schematic cross-sectional view of an organic light-emitting display device according to an exemplary embodiment of the present disclosure. (Refer to...) Figure 7 An organic light-emitting display device 500 according to an exemplary embodiment of the present disclosure includes an organic light-emitting display panel PNL1 and a viewing angle control film 200. The viewing angle control film 200 includes a first substrate material 210a, a first pattern electrode 220a, a transparent resin layer 130, a second pattern electrode 220b, and a second substrate material 210b. Figure 7 The viewing angle control film 200 in the organic light-emitting display device 500 shown is... Figure 5 The viewing angle control membrane 200 shown is essentially the same. Therefore, repeated descriptions will be omitted.

[0136] The organic light-emitting display panel PNL1 includes an organic light-emitting layer to display images using light emitted therefrom. For example, the organic light-emitting display panel PNL1 includes a substrate, thin-film transistors, an anode, an organic light-emitting stack, a cathode, and an encapsulation layer.

[0137] The substrate is the base material that supports the various components of the organic light-emitting display panel PNL1 and is formed of an insulating material. For example, the substrate can be a glass substrate or a plastic substrate. For example, the plastic substrate can be selected from polyimide, polyethersulfone, polyethylene terephthalate, and polycarbonate, but is not limited to these.

[0138] A thin-film transistor (TFT) is disposed on a substrate. The TFT includes a gate electrode, an active layer, a source electrode, and a drain electrode. For example, the active layer is disposed on the substrate, and a gate insulating layer is disposed on the active layer to insulate the active layer from the gate electrode. Furthermore, an interlayer insulating layer is disposed on the substrate to insulate the gate electrode from the source and drain electrodes. The source and drain electrodes, in contact with the active layer, are formed on the interlayer insulating layer. A planarization layer may be disposed on the TFT. The planarization layer planarizes the upper portion of the TFT. The planarization layer may include contact holes for electrically connecting the TFT to the anode.

[0139] The anode is disposed on the planarization layer. The anode is the component that supplies holes to the organic light-emitting layer and is formed of a conductive material with a high work function. The anode can be segmented for each sub-pixel. The cathode is disposed on the anode. The cathode can be formed of a metallic material with a low work function to smoothly supply electrons to the organic light-emitting layer. The cathode is formed as a single layer on the anode without patterning. That is, the cathode is not segmented for each sub-pixel area, but formed as a continuous monolayer. The organic light-emitting layer is disposed between the anode and the cathode. The organic light-emitting layer is the layer where electrons and holes combine to emit light. An encapsulation layer is disposed on the cathode to minimize degradation of the display panel due to moisture or oxygen and to planarize the upper surface of the organic light-emitting display panel PNL1.

[0140] A viewing angle control film 200 is disposed on the organic light-emitting display panel PNL1. For example, the viewing angle control film 200 is disposed on the encapsulation layer of the organic light-emitting display panel PNL1.

[0141] A viewing angle control film 200 is disposed on the organic light-emitting display panel PNL1 to provide a narrow viewing angle mode and a wide viewing angle mode. The narrow viewing angle mode provides a narrow viewing angle so that the user can see the image formed by light emitted from the organic light-emitting layer of the organic light-emitting display panel PNL1. The wide viewing angle mode provides a wide viewing angle so that others nearby can see the image. The configuration of the viewing angle control film 200, the narrow viewing angle mode, and the wide viewing angle mode are consistent with the above reference. Figures 1 to 3 , Figure 4A , Figure 4B and Figure 5 The content described is the same, so the repeated description will be omitted.

[0142] Figure 8 This is a schematic cross-sectional view of a liquid crystal display device according to an exemplary embodiment of the present disclosure. (Refer to...) Figure 8 The liquid crystal display device 600 according to an exemplary embodiment of the present disclosure includes a backlight unit BLU, a viewing angle control film 200, and a liquid crystal display panel PNL2. The viewing angle control film 200 includes a first substrate material 210a, a first pattern electrode 220a, a transparent resin layer 130, a second pattern electrode 220b, and a second substrate material 210b. Figure 8 The viewing angle control film 200 in the liquid crystal display device 600 shown is... Figure 5 The viewing angle control membrane 200 shown is essentially the same. Therefore, repeated descriptions will be omitted.

[0143] The backlight unit (BLU) includes multiple light sources to supply light to the liquid crystal display panel (PNL2). These light sources are electrically connected to a printed circuit board to be switched on or off. For example, the light sources can be light-emitting diodes (LEDs) with advantages such as high efficiency, high brightness, and low power consumption, but are not limited to these.

[0144] The backlight unit (BLU) includes a light diffusion plate disposed on multiple light sources to gather and diffuse the light emitted from the multiple light sources, so that the light is uniformly incident on the liquid crystal display panel (PNL2).

[0145] A reflective layer that reflects light generated by the light source onto the front surface is disposed on the rear surface of the backlight unit (BLU).

[0146] The liquid crystal display panel PNL2 is disposed on the backlight unit BLU. The liquid crystal display panel PNL2 includes a liquid crystal layer and controls the light transmittance of the liquid crystal to display images.

[0147] For example, the liquid crystal display panel PNL2 includes a lower substrate, an upper substrate, a lower polarizer, and an upper polarizer.

[0148] The lower substrate supports various components that constitute the liquid crystal display panel (PNL2). On the lower substrate, thin-film transistors (TFTs), pixel electrodes electrically connected to the TFTs, and a common electrode that forms an electric field together with the pixel electrodes are disposed. Therefore, the lower substrate can be called a thin-film transistor substrate. A liquid crystal layer containing liquid crystal molecules is disposed on the thin-film transistor substrate.

[0149] The upper substrate and the lower substrate are opposite each other. A color filter layer and a black matrix layer are disposed on the upper substrate. The color filter layer selectively transmits light with a specific wavelength. Light emitted from the backlight unit (BLU) passes through the liquid crystal layer and the color filter and is converted into light with various colors. The black matrix layer makes the thin-film transistors disposed on the lower substrate invisible to the outside of the liquid crystal display device 600.

[0150] A lower polarizer is disposed on the lower surface of the lower substrate to polarize the light emitted from the backlight unit BLU toward the liquid crystal display panel PNL2. An upper polarizer is disposed on the upper surface of the upper substrate and polarizes the light emitted to the outside of the liquid crystal display panel PNL2.

[0151] A viewing angle control film 200 is disposed between the backlight unit BLU and the liquid crystal display panel PNL2. The viewing angle control film 200 controls the travel angle of the light emitted from the backlight unit BLU to provide a wide viewing angle mode and a narrow viewing angle mode.

[0152] Specifically, the viewing angle control film 200 is disposed on the backlight unit BLU to provide a narrow viewing angle mode and a wide viewing angle mode. In the narrow viewing angle mode, the viewing angle of the light incident from the backlight unit BLU is controlled to be narrow, making the image displayed on the liquid crystal display panel PNL2 visible to the user. In the wide viewing angle mode, the viewing angle of the light incident from the backlight unit BLU is controlled to be wide, thereby providing a wide viewing angle so that people in the vicinity can see the image displayed on the liquid crystal display panel PNL2. The configuration of the viewing angle control film 200, the narrow viewing angle mode, and the wide viewing angle mode are consistent with the above reference. Figures 1 to 3 , Figure 4A , Figure 4B and Figure 5 The content described is the same, so the repeated description will be omitted.

[0153] The effects of this disclosure will be described in more detail below with reference to embodiments and comparative examples. However, the following embodiments are provided to illustrate this disclosure, but the scope of this disclosure is not limited thereto.

[0154] [Examples 1-1 to 1-5]

[0155] 10g of hollow carbon black (BET surface area 1270m²) 2(g / g, hollow portion volume ratio of 80 vol%) was added to 100 ml of 65 wt% nitric acid or sulfuric acid, and stirred at 100°C for 24 hours to allow the reaction to proceed. After the reaction was complete, the mixture was centrifuged at 7500 rpm for 15 minutes, and the precipitate was separated and washed with distilled water. Next, it was dried at 120°C for 24 hours to obtain hollow carbon black with carboxyl (-COOH) functional groups. Then, Isopar L (density 0.764 g / cm³) was prepared in a separate container. 3 Following this, polyisobutylene succinimide (trade name T151) was added at a concentration of 3 wt%. Next, surface-modified hollow carbon black was added to the solvent-dispersant mixture at a concentration of 2 wt%, followed by ultrasonic treatment for 2 hours. Then, inks were prepared by centrifugation at 2500 rpm for 30 minutes to remove impurities and ultrasonic treatment for 3 hours. Thus, inks with hollow carbon black dispersions in the inks having average particle sizes of 130 nm, 150 nm, 200 nm, 300 nm, and 500 nm were prepared.

[0156] [Comparative Examples 1-1 to 1-5]

[0157] 10g of carbon black (BET surface area 90m²) 2 / g) was added to 100 ml of nitric acid or sulfuric acid with a concentration of 65% by weight, and stirred at 100°C for 24 hours to allow the reaction to proceed. After the reaction was complete, the mixture was centrifuged at 7500 rpm for 15 minutes, and the precipitate was separated and washed with distilled water. Next, it was dried at 120°C for 24 hours to obtain hollow carbon black with a carboxyl (-COOH) functional group surface modified. Next, the solvent Isopar L (density 0.764 g / cm³) was prepared in a separate container. 3 Following this, polyisobutylene succinimide (trade name T151) was added at a concentration of 3 wt%. Next, surface-modified carbon black was added to the solvent-dispersant mixture at a concentration of 3 wt%, followed by ultrasonic treatment for 2 hours. Then, inks were prepared by centrifugation at 2500 rpm for 30 minutes to remove impurities and ultrasonic treatment for 3 hours. Thus, inks with carbon black dispersions in the inks having average particle sizes of 130 nm, 150 nm, 200 nm, 300 nm, and 500 nm were prepared.

[0158] [Experimental Example 1]

[0159] The physical properties of the inks from Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5 were evaluated. Physical property evaluation was performed using a dispersion analyzer (LUMiSizer) and the SEPView software. Table 1 and... Figure 9A and 9BThe average particle size of carbon black, carbon black density, density difference between solvent and carbon black, ink instability index, and particle settling velocity are shown. The instability index is obtained by measuring the ink transmittance over time and analyzing the shape and variation pattern of the transmittance distribution to express it numerically. Therefore, the smaller the instability index, the better the dispersion stability (at this point, concentration differences between samples are excluded). Particle settling velocity was analyzed using centrifugal force under accelerated gravity (150G, 500G, and 2000G).

[0160] Figure 9A This is a graph showing the density difference between particles and solvent, and the settling velocity, which vary depending on the average particle size of the hollow carbon black. Figure 9B This is a graph showing the density difference between particles and solvent, and the settling velocity, which vary depending on the average particle size of the carbon black.

[0161] [Table 1]

[0162]

[0163] First, refer to Table 1 and Figure 9A and Figure 9B It was confirmed that the carbon black contained in the inks of Examples 1-1 to 1-5 has a hollow structure with a hollow portion volume ratio of 80%, resulting in a density significantly lower than that of the carbon black contained in the inks of Comparative Examples 1-1 to 1-5. Therefore, it was confirmed that in the inks according to the examples, the density difference between carbon black and solvent is almost the same as at least 0.002. Conversely, it was confirmed that the density difference between carbon black and solvent in the inks according to the comparative examples is significantly higher than the density difference in the examples, at least 0.658, which is more than six times the maximum value of 0.106 in the examples.

[0164] Furthermore, the instability index of the ink according to the exemplary embodiment is 0.001 to 0.044, but the instability index of the ink according to the comparative example is 0.075 to 0.565, which is very high.

[0165] Furthermore, it was confirmed that the settling velocity of the ink particles according to the embodiment was 0.019 cm / year to 0.168 cm / year, which is very low, but the settling velocity of the ink particles according to the comparative example was 1.902 cm / year to 11.621 cm / year, which is almost 100 times that of the embodiment.

[0166] In summary, when hollow carbon black is used as a light-absorbing material, the density difference between particles and solvent is significantly reduced compared to carbon black without a hollow structure. Therefore, the excellent dispersion stability of the ink is confirmed, and the particle settling velocity is greatly reduced, thereby minimizing particle settling due to gravity. Specifically, the results of Examples 1-1 to 1-5 confirm that when the average particle size of the hollow carbon black dispersed in inks smaller than 300 nm is in the range of 130 nm to 200 nm, the dispersion stability of the ink is superior, and particle settling due to gravity is effectively suppressed.

[0167] [Experimental Example 2]

[0168] For Examples 1-2 and Comparative Example 1-1, which had the lowest density difference, instability index, and settling velocity in the measured example and comparative example groups, the charge of carbon black (zeta potential) and the viscosity of the ink were additionally measured.

[0169] The measurements confirmed that the inks according to Examples 1-2 had a zeta potential of -26 mV and a viscosity (25°C) of 1.74 cP. Furthermore, the inks according to Comparative Example 1-1 were confirmed to have a zeta potential of -18 mV and a viscosity (25°C) of 3.29 cP.

[0170] Compared with the ink according to Comparative Example 1-1, the ink according to Example 1-2 has superior electrical properties and lower viscosity. Therefore, when the ink according to Example 1-2 is applied to a viewing angle control film, the driving characteristics are expected to be superior to those of the ink according to Comparative Example 1-1.

[0171] [Example 2]

[0172] Two cyclic olefin films, each 125 μm thick, were prepared, in which multiple ITO patterned electrodes (electrode material was ITO, and each patterned electrode was 200 nm thick and 20 μm wide) were formed. A transparent resin layer (105 μm thick) containing acrylic resin was formed on the ITO patterned electrodes of the first cyclic olefin film. Then, multiple receiving units were formed on the transparent resin layer using an imprinting process (or mastering process). Next, the ink prepared in Examples 1-2 was injected into the multiple receiving units. Then, a second cyclic olefin film was bonded to the first cyclic olefin film on which the transparent resin layer was formed using an optically transparent adhesive layer (20 μm) to prepare a film with [missing information - likely related to ITO patterning]. Figure 6 The view control film with the same structure shown is (W1: 21.5 μm, W2: 5 μm, W3: 20.44 μm, W4: 37 μm, D1: 105 μm, D2: 10 μm, θa: 97°, θb: 92°).

[0173] [Comparative Example 2]

[0174] In Comparative Example 2, the viewing angle control film was prepared using the same method as in Example 2, except that the ink according to Comparative Example 1-1 was injected into a plurality of containment units instead of the ink according to Examples 1-2.

[0175] [Experiment Example 3]

[0176] To examine the driving characteristics of the viewing angle control films prepared according to Example 2 and Comparative Example 2, the change in brightness over time was measured. Brightness was measured using a SpectraDuo PR-680 after the viewing angle control films were bonded to an organic light-emitting display panel. The results are shown below. Figure 10 , Figure 11A and Figure 11B middle.

[0177] Furthermore, the viewing angle control films prepared according to Example 2 and Comparative Example 2 were stored at 60°C for 1000 hours to accelerate particle sedimentation, and then particle sedimentation was assessed visually. The results are shown in... Figure 12A , Figure 12B , Figure 13A and Figure 13B middle.

[0178] Figure 10 This is a graph showing the change in brightness of the film over time according to the viewing angle control of Example 2 and Comparative Example 2. Figure 11A This is a graph showing the brightness variation over time of the narrow viewing angle mode of the viewing angle control film according to Example 2 and Comparative Example 2. Figure 11B This is a graph showing the brightness variation over time in the wide-viewing-angle mode of the viewing angle control film according to Example 2 and Comparative Example 2. Figure 12A This is a photograph taken from the front when the viewing angle control film according to Example 2 is in narrow viewing angle mode. Figure 12B This is a photograph taken from the 30° side surface when the viewing angle control film according to Example 2 is in narrow viewing angle mode. Figure 13A This is a photograph taken from the front when the viewing angle control film is in narrow viewing angle mode according to Comparative Example 2. Figure 13B The photograph is taken from the 30° side surface when the viewing angle control film of Comparative Example 2 is in narrow viewing angle mode.

[0179] First, refer to Figure 10 It was confirmed that the brightness of the viewing angle control film according to Example 2 was higher than that of the viewing angle control film according to Comparative Example 2. It was also confirmed that the charge of the inks according to Examples 1-2 was higher than that of the inks according to Comparative Example 1-1, thus exhibiting superior electrical properties. In other words, by improving the electrical properties of the inks according to Examples 1-2, it was determined that the brightness of Example 2 was significantly improved compared to that of Comparative Example 2.

[0180] Furthermore, the mode switching speed of Example 2 was 6.6 seconds, while that of Comparative Example 2 was 9.5 seconds. Therefore, the mode switching speed of the viewing angle control film of Example 2 is superior to that of Comparative Example 2. It was confirmed that the viscosity of the inks according to Examples 1-2 was lower than that of the inks according to Comparative Example 1-1. The lower the viscosity, the better the migration rate of charged carbon black when voltage is applied to the viewing angle control film. In other words, it is believed that the viewing angle control film according to Example 2 includes inks with lower viscosity than those of Comparative Example 2, and therefore its mode switching speed is faster than that of Comparative Example 2.

[0181] Refer to together Figure 11A and Figure 11B It was confirmed that the brightness of the viewing angle control film according to Example 2 was lower than that of the viewing angle control film according to Comparative Example 2 in narrow viewing angle mode, but higher in wide viewing angle mode. Therefore, it was confirmed that the dual stability of the ink of Example 2 is superior to that of Comparative Example 2, and thus the driving characteristics are superior in both narrow and wide viewing angle modes.

[0182] In addition, refer to Figure 11B It was confirmed that in the viewing angle control film according to Example 2, the brightness was stably maintained without decreasing over time, but the brightness of the viewing angle control film according to Comparative Example 2 decreased sharply after 100 seconds. Therefore, it can be seen that in the ink used for the viewing angle control film according to Example 2, particle sedimentation is minimized and the dispersion stability of the ink is superior to that of the ink in Comparative Example 2. It was confirmed that in the ink used for the viewing angle control film of Comparative Example 2, particles settle due to gravity; therefore, as... Figure 11B As shown, the brightness gradually decreases.

[0183] Reference Figure 12A and Figure 12B This confirmed that the front brightness of the viewing angle control film according to Example 2 was excellent in the narrow viewing angle mode, and the screen was completely blocked as observed from the 30° side surface. Conversely, referring to... Figure 13A and Figure 13B It was confirmed that, in narrow viewing angle mode, the front brightness of the viewing angle control film according to Comparative Example 2 decreased compared to the embodiment. Furthermore, it was confirmed that, in the viewing angle control film according to Comparative Example 2, the screen was not obscured when viewed from a 30° side surface. This indicates that in the ink used in the viewing angle control film of Comparative Example 2, particles cannot remain dispersed and tend to settle due to gravity.

[0184] [Experiment Example 4]

[0185] The photographic profile of the viewing angle control film according to Example 2 was analyzed. After the viewing angle control film according to Example 2 was bonded to an organic light-emitting display panel, the brightness was measured according to the viewing angle in both wide and narrow viewing angle modes. The results of the photographic profile analysis are shown below. Figure 14 Table 2, as a reference example, also shows the results of photographic contour analysis of an organic light-emitting display panel excluding the viewing angle control film.

[0186] Figure 14 This is a graph showing the brightness distribution of the organic light-emitting display device according to the viewing angle according to Embodiment 2 and the reference example.

[0187] [Table 2]

[0188]

[0189] Refer to Table 2 and Figure 14 The photographic outline of the organic light-emitting display device according to Reference Example 2, excluding the viewing angle control film, follows a Gaussian function curve that is symmetrical about the two side surfaces with respect to 0° of the front surface. Therefore, the transmittance of the 29° side surface and the -29° side surface are equal with respect to the front surface.

[0190] It was confirmed that the organic light-emitting display device including the viewing angle control film according to Embodiment 2 has very high frontal (0°) transmittance in narrow viewing angle mode, but very low transmittance outside the viewing angle range of -20° to 15°. Therefore, the organic light-emitting display device including the viewing angle control film according to Embodiment 2 has low lateral transmittance in narrow viewing angle mode, making the screen appear dark.

[0191] It was confirmed that, compared to the narrow viewing angle mode, the organic light-emitting display device including the viewing angle control film according to Example 2 exhibits relatively high transmittance in the wide viewing angle mode within a wide viewing angle range. The organic light-emitting display device according to Example 2 provides the same viewing angle as the reference example in the wide viewing angle mode.

[0192] Furthermore, in the viewing angle control film according to Embodiment 2, the angle θa formed by the lower surface of the receiving unit and the first connecting unit and the angle θb formed by the lower surface and the second connecting unit are different. Therefore, it was confirmed that the transmittance of the 29° side surface is significantly different from that of the -29° side surface in both wide-viewing-angle mode and narrow-viewing-angle mode.

[0193] Exemplary embodiments of this disclosure can also be described as follows.

[0194] According to one aspect of this disclosure, the viewing angle control film includes: a first substrate material; a first electrode disposed on the first substrate material; a transparent resin layer disposed on the first electrode and having a plurality of containment units; a second electrode disposed on the transparent resin layer; and a second substrate material disposed on the second electrode, wherein an ink comprising charged hollow carbon black and a solvent is contained in each of the plurality of containment units.

[0195] Each of the plurality of receiving units may be formed opposite to the second electrode, may be configured to be spaced apart from each other along a first direction perpendicular to the thickness direction of the transparent resin layer, and may extend along a second direction perpendicular to the thickness direction and the first direction.

[0196] Each of the plurality of receiving units may include a lower surface opposite to the first electrode, an upper surface opposite to the lower surface, and a connecting unit connecting the lower surface and the upper surface.

[0197] The upper surface can be spaced apart from the second electrode, and the distance from the upper surface to the second electrode can be from 5 μm to 20 μm.

[0198] The distance from the bottom surface to the top surface can be between 70 μm and 160 μm.

[0199] The width of the lower surface can be from 5 μm to 30 μm, and the width of the upper surface can be from 1 μm to 15 μm, and the width of the lower surface can be greater than the width of the upper surface.

[0200] The distance between the lower surfaces of adjacent containment units can be 15 μm to 50 μm, and the distance between the upper surfaces of adjacent containment units can be 25 μm to 60 μm.

[0201] The connecting unit may include a first connecting unit that connects one end of the lower surface to one end of the upper surface and a second connecting unit that connects the other end of the lower surface to the other end of the upper surface, and the angle formed by the first connecting unit and the lower surface may be different from the angle formed by the second connecting unit and the lower surface.

[0202] The angle formed by the first connecting unit and the lower surface can be from 96° to 105°, and the angle formed by the second connecting unit and the lower surface can be from 90° to 95°.

[0203] Each of the first and second electrodes can be patterned to correspond to each of the plurality of containment cells.

[0204] The first substrate material and the second substrate material may be formed from one or more materials selected from cyclic olefin polymers, cyclic olefin copolymers, cellulose triacetate, polycarbonate, polyethylene terephthalate and polyimide, respectively.

[0205] Hollow carbon black may include a hollow portion and a shell surrounding the hollow portion and including the carbon black.

[0206] The volume ratio of the hollow section can be from 50% to 90% by volume.

[0207] The density of charged hollow carbon black can be 0.60 g / cm³. 3 Up to 0.90 g / cm 3 .

[0208] The BET surface area of ​​charged hollow carbon black can be 500 m². 2 / g to 1500m 2 / g.

[0209] The average particle size of charged hollow carbon black can be from 100 nm to 500 nm.

[0210] The ink may further include polyisobutylene succinimide as a dispersant.

[0211] When no voltage is applied to the first and second electrodes, the charged hollow carbon black can be uniformly dispersed in each of the multiple containment cells and the viewing angle control film can operate in a narrow viewing angle mode. When a voltage is applied to the first and second electrodes, the charged hollow carbon black can aggregate toward the upper surface of the multiple containment cells and the viewing angle control film can operate in a wide viewing angle mode.

[0212] According to another aspect of this disclosure, a display device includes: a display panel; and a viewing angle control film disposed above or below the display panel, wherein the viewing angle control film is the aforementioned viewing angle control film.

[0213] The display panel may be a liquid crystal display panel and may further include a backlight unit disposed below the display panel, and a viewing angle control film may be disposed between the liquid crystal display panel and the backlight unit.

[0214] The display panel can be an organic light-emitting display panel, and the viewing angle control film can be placed above the organic light-emitting display panel.

[0215] Although exemplary embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, the present disclosure is not limited thereto and may be implemented in many different forms without departing from the technical concept of the present disclosure. Therefore, the exemplary embodiments of the present disclosure are provided for illustrative purposes only and are not intended to limit the technical concept of the present disclosure. The scope of the technical concept of the present disclosure is not limited thereto. Therefore, it should be understood that the above exemplary embodiments are exemplary in all respects and do not limit the present disclosure. The scope of protection of the present disclosure should be interpreted based on the appended claims, and all technical concepts within the equivalent scope thereof should be understood to fall within the scope of protection of the present disclosure.

Claims

1. A viewing angle control membrane, comprising: First substrate material; A first electrode is disposed on the first substrate material; A transparent resin layer is disposed on the first electrode and has a plurality of receiving units; The second electrode is disposed on the transparent resin layer; as well as A second substrate material is disposed on the second electrode. The ink, comprising charged hollow carbon black and solvent, is contained in each of the plurality of containment units. The average particle size of the charged hollow carbon black is 140 nm to 250 nm.

2. The viewing angle control membrane according to claim 1, wherein, Each of the plurality of receiving units is formed opposite to the second electrode, is configured to be spaced apart from each other along a first direction perpendicular to the thickness direction of the transparent resin layer, and extends along a second direction perpendicular to both the thickness direction and the first direction.

3. The viewing angle control membrane according to claim 1, wherein, Each of the plurality of receiving units includes a lower surface opposite to the first electrode, an upper surface opposite to the lower surface, and a connecting unit connecting the lower surface and the upper surface.

4. The viewing angle control membrane according to claim 3, wherein, The upper surface is spaced apart from the second electrode, and the distance from the upper surface to the second electrode is 5 μm to 20 μm.

5. The viewing angle control membrane according to claim 3, wherein, The distance from the lower surface to the upper surface is 70 μm to 160 μm.

6. The viewing angle control membrane according to claim 3, wherein, The width of the lower surface is 5 μm to 30 μm, the width of the upper surface is 1 μm to 15 μm, and the width of the lower surface is greater than the width of the upper surface.

7. The viewing angle control membrane according to claim 3, wherein, The distance between the lower surfaces of adjacent containment units is 15 μm to 50 μm, and the distance between the upper surfaces of adjacent containment units is 25 μm to 60 μm.

8. The viewing angle control membrane according to claim 3, wherein, The connecting unit includes a first connecting unit that connects one end of the lower surface to one end of the upper surface and a second connecting unit that connects the other end of the lower surface to the other end of the upper surface, and the angle formed by the first connecting unit and the lower surface is different from the angle formed by the second connecting unit and the lower surface.

9. The viewing angle control membrane according to claim 8, wherein, The angle formed by the first connecting unit and the lower surface is 96° to 105°, and the angle formed by the second connecting unit and the lower surface is 90° to 95°.

10. The viewing angle control membrane according to claim 1, wherein, Each of the first electrode and the second electrode is patterned to correspond to each of the plurality of containment units.

11. The viewing angle control membrane according to claim 1, wherein, The first substrate material and the second substrate material are respectively formed from one or more materials selected from cyclic olefin polymers, cyclic olefin copolymers, cellulose triacetate, polycarbonate, polyethylene terephthalate and polyimide.

12. The viewing angle control membrane according to claim 1, wherein, The charged hollow carbon black includes a hollow portion and a shell surrounding the hollow portion and containing the carbon black.

13. The viewing angle control membrane according to claim 12, wherein, The volume ratio of the hollow portion is 50% to 90% by volume.

14. The viewing angle control membrane according to claim 1, wherein, The density of the charged hollow carbon black is 0.60 g / cm³. 3 Up to 0.90 g / cm 3 .

15. The viewing angle control membrane according to claim 1, wherein, The charged hollow carbon black has a BET surface area of ​​500 m². 2 / g to 1500m 2 / g.

16. The viewing angle control membrane according to claim 1, wherein, The ink also includes polyisobutylene succinimide as a dispersant.

17. The viewing angle control membrane according to claim 3, wherein, When no voltage is applied to the first and second electrodes, the charged hollow carbon black is uniformly dispersed in each of the plurality of containment units and the viewing angle control film operates in a narrow viewing angle mode. When voltage is applied to the first and second electrodes, the charged hollow carbon black aggregates toward the upper surface of the plurality of containment units and the viewing angle control film operates in a wide viewing angle mode.

18. A display device, comprising: Display panel; as well as A viewing angle control film, wherein the viewing angle control film is disposed above or below the display panel. The viewing angle control film is the viewing angle control film according to any one of claims 1 to 17.

19. The display device according to claim 18, wherein, The display panel is a liquid crystal display panel and also includes a backlight unit disposed below the display panel, and the viewing angle control film is disposed between the liquid crystal display panel and the backlight unit.

20. The display device according to claim 18, wherein, The display panel is an organic light-emitting display panel, and the viewing angle control film is disposed above the organic light-emitting display panel.

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