KR102521896B1 - Privacy protecting film and display device comrpising the same - Google Patents

Abstract

The present invention relates to a privacy protection film, and the privacy protection film according to an embodiment of the present invention includes a light transmission area that transmits light and a light blocking area disposed between the light transmission area to block light in a specific direction. A light control layer, a plurality of first electrodes disposed on the light blocking region of the light control layer, a second electrode spaced apart from the plurality of first electrodes at regular intervals, and disposed between the light control layer and the second electrode, electrophoresis and a light diffusion layer containing particles. The security mode and the sharing mode can be freely switched as needed by using the light whose viewing angle is controlled according to the positional change of the electrophoretic particles, or by re-scattering the controlled light.

Description

Privacy protection film and display device including the same {PRIVACY PROTECTING FILM AND DISPLAY DEVICE COMRPISING THE SAME}

The present invention relates to a privacy protection film and a display device including the same, and more particularly, to a privacy protection film providing a security mode providing a narrow viewing angle and a sharing mode providing a wide viewing angle, and a display device including the same .

As the demand for personal privacy protection increases, various related products are being developed in various places. Among products that guarantee personal privacy, demand for privacy protection devices that are attached to various display devices such as mobile phones, tablet PCs, and monitors to block side transmission of light and narrow the viewing angle are also increasing year by year.

In this regard, conventionally, a privacy protection device in the form of a film in which a light transmission area for transmitting light and a light blocking area for blocking light in a specific direction are alternately formed has been used. In this regard, referring to FIG. 1A, the privacy protection device 100a includes a lower film 110a, an upper film 120a, and a viewing angle control layer 130a disposed between the lower film 110a and the upper film 120a. includes The viewing angle control layer 130a includes a light transmitting region 131a and a light blocking region 132a disposed between the light transmitting region 131a to block or absorb light. Among the light incident from the bottom, light having an incident angle greater than or equal to a certain angle is absorbed or blocked by the repeatedly formed light blocking region 132a, and thus does not pass through the viewing angle control layer 130a. As a result, the light transmittance is significantly reduced at a viewing angle greater than a certain angle, and privacy protection may be implemented.

However, in the case of the conventional privacy protection device 100a shown in FIG. 1A, the viewing angle cannot be restored to the original state unless the device itself is removed, so there is an inconvenience in that the device itself must be removed when the privacy function is unnecessary. .

Recently, in order to solve this inconvenience, a switchable privacy protection device that can be used by selectively adjusting a viewing angle according to whether an electrical signal is applied without attaching or detaching the device has been developed. As the light blocking material of the switchable privacy protection device described above, a method using a polymer dispersed liquid crystal (PDLC), a polymer network liquid crystal (PNLC), or an additional separate LCD structure, and There is a method using an electro-chromic material, and the like.

1B is a cross-sectional view of a conventional privacy protection device including an electrochromic material. Referring to FIG. 1B, a conventional privacy protection device 100b including an electrochromic material includes a lower film 110b, an upper film 120b, a microstructure layer 130b formed on the lower film 110b, and a first It includes an electrode 150b, a second electrode 160b and an electrochromic material 140b. Specifically, the lower film 110b and the upper film 120b are disposed to face each other, and the microstructure layer 130b including recessed grooves is disposed on the lower film 110b. The first electrode 150b is disposed in the groove of the microstructure layer 130b, and the second electrode 160b is disposed under the upper film 120b. Electrochromic materials 141b and 142b are filled between the groove of the microstructure layer 130b and between the microstructure layer 130b and the upper substrate 120b. At this time, when a voltage is applied to the first electrode 150b and the second electrode 160b, the electrochromic material 141b included in the groove of the microstructure layer 130b is discolored black, and repeatedly to form a blocking area.

However, in the privacy protection device including the electrochromic material shown in FIG. 1B, there is a problem that the electrochromic material has poor light absorption performance or poor lateral transmittance compared to black bodies such as general dyes or pigments, and provides a narrow viewing angle. There are problems in that the speed of switching between the security mode and the shared mode providing a wide viewing angle is slow, and driving stability is deteriorated during continuous mode switching. Therefore, although research is still in progress to solve this problem, a privacy protection device of a desired level has not yet been developed.

An object to be solved by the present invention is to provide a privacy protection film capable of selectively switching between a sharing mode and a security mode as needed without removing the privacy protection device itself from the display panel.

In addition, another problem to be solved by the present invention is to improve light transmittance in a shared mode providing a wide viewing angle.

In addition, another problem to be solved by the present invention is to quickly switch between a protection mode and a sharing mode and improve driving stability.

The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the following description.

In order to solve the above problems, a privacy protection film according to an embodiment of the present invention includes a light transmission area that transmits light and a light blocking area disposed between the light transmission area to block light in a specific direction. A control layer, a plurality of first electrodes disposed on the light blocking region of the light control layer, a second electrode spaced apart from the plurality of first electrodes at regular intervals, and disposed between the light control layer and the second electrode, electrophoretic particles It includes a light diffusion layer comprising a. The security mode and the sharing mode can be freely switched as needed by using the light whose viewing angle is controlled according to the positional change of the electrophoretic particles, or by re-scattering the controlled light.

A display device according to an embodiment of the present invention includes a display panel and a privacy protection film on one surface of the display panel, wherein the privacy protection film includes a light transmission area and a light blocking area repeated in one direction perpendicular to a thickness direction. A first film comprising a first film, a second film facing each other at a predetermined distance from the first film, a first electrode disposed on the light blocking region of the first film, a second electrode disposed on the front surface of the second film, and a first and electrophoretic particles disposed between the film and the second film.

Other embodiment specifics are included in the detailed description and drawings.

The present invention can provide a privacy protection film capable of freely switching between a sharing mode providing a wide viewing angle and a security mode providing a narrow viewing angle as needed.

The present invention can provide a privacy security film capable of greatly improving light transmittance in a sharing mode.

The present invention can provide a privacy security film with generally improved luminance and a fast switching speed between a security mode and a sharing mode.

Effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the present invention.

1A and 1B are cross-sectional views illustrating a conventional privacy protection device.
Figure 2a is a cross-sectional view for explaining a privacy protection film according to an embodiment of the present invention.
2B is an enlarged image for explaining electrophoretic particles included in a privacy protection film according to an embodiment of the present invention.
3a and 3b are cross-sectional views illustrating a security mode and a sharing mode when driving a privacy protection film according to an embodiment of the present invention.
4 is a cross-sectional view for explaining a privacy protection film according to another embodiment of the present invention.
5A and 5B are cross-sectional views illustrating performance improvement in a security mode according to a change in electrode width.
6 is a graph showing a plot of light emission versus viewing angle for privacy protection films according to Examples and Comparative Examples.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention pertains. It is provided to completely inform the person who has the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are illustrative, so the present invention is not limited to the illustrated details. Like reference numbers designate like elements throughout the specification. In addition, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists', etc. mentioned in the present invention is used, other parts may be added unless 'only' is used. In the case where a component is expressed in the singular, the case including the plural is included unless otherwise explicitly stated.

In interpreting the components, even if there is no separate explicit description, it is interpreted as including the error range.

In the case of a description of a positional relationship, for example, 'on top of', 'on top of', 'at the bottom of', 'next to', etc. Or, unless 'directly' is used, one or more other parts may be located between the two parts.

When an element or layer is referred to as “on” another element or layer, it includes all cases where another element or layer is directly on top of another element or another layer or other element intervenes therebetween.

In addition, although 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 another. Therefore, the first component mentioned below may also be the second component within the technical spirit of the present invention.

Like reference numbers designate like elements throughout the specification.

The size and thickness of each component shown in the drawings are shown for convenience of description, and the present invention is not necessarily limited to the size and thickness of the illustrated components.

Each feature of the various embodiments of the present invention can be partially or entirely combined or combined with each other, technically various interlocking and driving are possible, and each embodiment can be implemented independently of each other or can be implemented together in a related relationship. may be

In this specification, the security mode means a mode that provides a narrow viewing angle so that only the user can see the displayed image. In the security mode, sufficient light transmittance can be satisfied only within a specific viewing angle, and the light transmittance becomes very low outside the specific viewing angle, making it impossible to recognize a displayed image.

The sharing mode means a mode that provides a wide viewing angle so that a displayed image can be seen not only by the user but also by other people nearby. In the sharing mode, a sufficient light transmittance can be satisfied even at a wider viewing angle compared to the security mode, so that an image can be recognized even at a viewing angle at which an image cannot be recognized in the security mode.

Hereinafter, the present invention will be described with reference to the drawings.

2A is a cross-sectional view illustrating a privacy protection film according to an embodiment of the present invention, and FIG. 2B is an enlarged image for explaining electrophoretic particles included in the privacy protection film according to an embodiment of the present invention.

Referring to FIG. 2A , the privacy protection film 200 according to an embodiment of the present invention includes a first film 210, a second film 220, a first electrode 250, a second electrode 260, a light A control layer 230 and a light diffusion layer 240 including electrophoretic particles 241 are included.

The first film 210 and the second film 220 prevent the light control layer 230 and the light diffusion layer 240 from being bent or twisted and protect the light control layer 230 and the light diffusion layer 240 from the external environment. It is a base film for protection. The first film 210 and the second film 220 are spaced apart at regular intervals and disposed to face each other. The first film 210 and the second film 220 may be made of a transparent material. For example, the first film 210 and the second film 220 may be made of polycarbonate, but are not limited thereto. In FIG. 2A , the first film 210 and the second film 220 are shown, but may be omitted if necessary.

The light control layer 230 is a layer that limits the viewing angle according to the user's viewing angle. By reducing the light transmittance at a specific viewing angle, it is possible to realize privacy protection by preventing others from viewing the image from the side.

The light control layer 230 is disposed on the first film 210 . Although a structure in which the light control layer 230 is disposed on the first film 210 is shown in FIG. 2A , the light control layer 230 may be integrated with the first film 210 .

The light control layer 230 includes a light transmission region 231 and a light blocking region 232 . The light transmission region 231 functions to transmit light, and the light blocking region 232 is disposed between the light transmission regions 231 to block light in a specific direction.

The light transmitting region 231 and the light blocking region 232 may be made of different materials or the same material. For example, the light transmitting region 231 may be formed of a material having high light transmittance, and the light blocking region 232 may be formed of a light blocking material that absorbs or reflects light. More specifically, a thermoplastic resin, a thermosetting resin, a UV curing resin, or the like may be used for the light transmission region 231, and examples of the resin include cellulose, polyolefin, polyester resin, polystyrene, polyurethane, polyvinyl chloride, and polyacrylic resin. , can be formed of a transparent material such as polycarbonate. On the other hand, the light blocking region 232 may be formed of a dark color pigment such as black or gray pigment, a dark color dye, a metal such as aluminum or silver, a metal oxide, or a dark polymer. In addition, the light blocking region 232 may be formed by irradiating a laser onto the transparent film to form black markings on the transparent film. In this case, the light transmitting region 231 and the light blocking region 232 are made of the same material.

The light transmitting region 231 and the light blocking region 232 are alternately arranged in one direction perpendicular to the thickness direction (z-axis direction) of the light control layer 230 . That is, the light transmitting regions 231 are repeatedly disposed in the x-axis direction, and the light blocking region 232 is disposed between the light transmitting regions 231 . Meanwhile, the light transmitting region 231 and the light blocking region 232 have shapes extending in different directions perpendicular to the thickness direction. That is, the light transmitting region 231 and the light blocking region 232 have a shape arranged in a straight line in the y-axis direction.

Each light blocking region 232 has a height “H” and a width “W”, and is spaced apart from each other by a specific distance (P). Although not limited thereto, the light blocking region 232 preferably has a height of 80 μm to 120 μm, a width of 15 μm to 20 μm, and an interval of 30 μm to 60 μm. When the shape of the light blocking region 232 satisfies the above range, the light transmittance is significantly reduced at a viewing angle of 30° or more, so that a security mode may be implemented.

The first electrode 250 and the second electrode 260 are electrodes for forming an electric field by applying a voltage to the light diffusion layer 240 . The first electrode 250 and the second electrode 260 are made of a conductive material. In addition, the first electrode 250 and the second electrode 260 are made of indium tin oxide (ITO), aluminum doped zinc oxide (AZO), or fluorine tin oxide (FTO) to ensure transmittance of the privacy protection film 200. , PEDOT: PSS, may be made of a transparent conductive material such as silver-nanowire (AgNW), but is not limited thereto.

The first electrode 250 is disposed on the light blocking region 232 of the light control layer 230 . Specifically, the first electrode 250 may be disposed on the upper surface of each light blocking region 232 and may be composed of a plurality of electrodes. That is, the first electrode 250 has the same width as the width “W” of the light blocking region 232, is repeatedly arranged in the x-axis direction like the light blocking region 232, and has a shape arranged in the y-axis direction. have The second electrode 260 is disposed below the second film 220 . The second electrode 260 may be spaced apart from the first electrode 250 at regular intervals. When a voltage is applied to the second electrode 260 and the electrophoretic particles 241 are disposed on the second electrode 260, the second electrode 260 covers the entire light control layer 230, the lower surface of the second film 220. may be disposed as a single electrode.

The light diffusion layer 240 is a layer that controls whether or not the light passing through the light control layer 230 is diffused and the degree of diffusion. As the light diffusion layer 240 passes through the light control layer 230 , light having a controlled viewing angle may be used as it is or the controlled viewing angle may be invalidated. That is, the light diffusion layer 240 may switch between a security mode having a narrow viewing angle and a sharing mode having a wide viewing angle through a structural change of the light diffusion layer 240 .

The light diffusion layer 240 is disposed between the first electrode 250 and the second electrode 260 . Specifically, the light diffusion layer 240 includes a solvent 242 filling between the first electrode 250 and the second electrode 260 and a plurality of electrophoretic particles 241 dispersed in the solvent 242 .

The electrophoretic particles 241 function to diffuse light passing through the light control layer 230 . A detailed description of a process in which the light diffusion layer 240 and the electrophoretic particles 241 adjust the security mode and the sharing mode will be described later.

Referring to FIG. 2B , the electrophoretic particles 241 include hollow particles, a charge control agent (CCA), a binder resin, and a surfactant.

The hollow particle is a particle having a hollow shape inside. The hollow particles are particles that function to scatter light, and may further increase light scattering by including air in the hollow part.

The hollow particles may be organic particles, inorganic particles, or organic-inorganic composite particles. for example,

Hollow particles include, for example, silica (SiO ₂ ), alumina (Al ₂ O ₃ ), titania (TiO ₂ ), zirconia (ZrO ₂ ), ceria (CeO ₂ ), vanadia (V ₂ O ₅ ), and any of these It may be an inorganic particle selected from the group consisting of combinations, and may be an organic particle such as polystyrene, but is not limited thereto.

The hollow particles may be formed by, for example, a method selected from the group consisting of spin coating, solvent evaporation, electrophoresis, vertical-dipping, and combinations thereof, but is not limited thereto.

The diameter of the hollow particles is preferably 0.2 μm to 3.0 μm, more preferably 0.5 μm to 2.0 μm. When the diameter of the hollow particles is less than 0.50 μm, the function of scattering light is insufficient, and when the diameter is greater than 3.0 μm, the electrophoretic particles 241 dispersed in the solvent are visually recognized and the basic light of the light diffusion layer 240 is visible. Transmittance may decrease.

The charge control agent is bonded to the hollow particle and has a functional group such as a carboxy group (-COOH) at the end so that the electrophoretic particle 241 is charged. That is, the electrophoretic particles 241 become charged particles by the charge control agent. Here, the charge control agent can be appropriately selected depending on the charge to be imparted to the charged particles. For example, the charge control agent may include any one of organic sulfates, sulfonates, MetalSoaps, block or comb polymers, Zwitter ions, phosphates and metal complexes. For example, the metal complex is CU ^- , Ca ^- , Mn ^- , Ni ^- , Zn ^- and Fe ^- naphthenic acid metal salt having any one complex, Ba ^- , Al ^- , Zn ^- , Cu ^- , Pb ^- And Fe ^- may be stearic acid or tert- salicylic acid or butyl salicylic acid metal salt having any one of the complexes.

The content of the charge control agent may be 0.1 part by weight to 40 parts by weight relative to the content of the hollow particles in consideration of the occurrence of yellowing of the electrophoretic particles 241 and the degree of imparting the amount of charge, but is not limited thereto.

The binder resin binds the hollow particles and the charge control agent inside and binds the surfactant outside. For example, binder resins include polyesters, polyacrylates, polymethacrylates, polyethylenes, polystyrenes, polyacrylates, polymethacrylates, polystyrenes, acrylurethane resins, acrylic fluororesins, fluororesins, silicone resins and phenolic resins. etc., but is not limited thereto.

The surfactant prevents aggregation due to interaction between heterogeneous particles having different polarities. A surfactant may contain an amine group in its molecule. In addition, the surfactant may include an electric charge of any one of ester, sulfone salt, alkyl, aryl, alkyl sulfone salt, olefin, alcohol and carboxylic acid in the molecule. For example, the surfactant may be an amine salt, an alkyl ammonium, an olefin sulfonate, an alkyl sulfate ester salt, an alkyl ether sulfate, an alkyl sulfonate, polyisobutylene succinimide, and polyoxyethylene lauryl ether, but is limited thereto. it is not going to be

The content of the surfactant may be 0.1 part by weight to 50 parts by weight relative to the content of the airborne particles in consideration of aggregation between the electrophoretic particles 241 .

Referring to FIG. 2B , the electrophoretic particle 241 may have a structure in which the hollow particle 241a forms a core and the charge control agent 241b surrounds the hollow particle. The binder resin 241c binds to the hollow particles 241a and the charge control agent 241b on the inside, and binds to the surfactant 241d on the outside. The surfactant 241d is disposed in a form surrounding the outside of the charge control agent 241b to suppress aggregation between the electrophoretic particles 241 and improve dispersibility.

Solvent 242 may be a non-polar solvent. For example, the solvent 242 includes aromatic hydrocarbons such as benzene, toluene, xylene, phenylxylylethane, diisopropylnaphthalene, and naphthenic hydrocarbons, hexane, dodecylbenzene, cyclohexane, kerosene, paraffin hydrocarbons, and the like. aliphatic hydrocarbons, halogenated hydrocarbons such as chloroform, trichloroethylene, tetrachloroethylene, trifluoroethylene, tetrafluoroethylene, dichloromethane, ethyl bromide, tricredyl phosphate, trioctyl phosphate, octyldiphenyl phosphate, Phosphoric acid esters such as tricyclohexyl phosphate, phthalic acid esters such as dibutyl phthalate, dioctyl phthalate, dilauryl phthalate, and dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, dioctyl sebacate, seba Carboxylate esters such as dibutyl acetate, dioctyl adipate, trioctyl trimellitate, triethyl citrate, octyl maleate, dibutyl maleate and ethyl acetate, isopropylbiphenyl and isoamylbiphenyl , chlorinated paraffin, diisopropylnaphthalene, 1,1-ditolylethane, 1,2-ditolylethane, 2,4-ditertiary aminophenol, N,N-dibutyl-2-butoxy-5-tert - May include octyl aniline, but is not limited thereto. Organic solvents may be used alone or in combination. Among the above solvents, paraffinic hydrocarbons are particularly preferred as the dispersion of the electrophoretic particles 241.

In the light diffusion layer 240 composed of the solvent 242 and the electrophoretic particles 241, the concentration of the electrophoretic particles 241 is not limited thereto, but is preferably 0.01% by weight to 0.4% by weight, particularly 0.1% by weight. It is more preferably 0.3% by weight to 0.3% by weight. When the concentration of the electrophoretic particles 241 is less than the above range, the light diffusion effect in the sharing mode is insufficient because the content of the electrophoretic particles 241 is small, and when the concentration of the electrophoretic particles 241 is greater than the above range, Since the dispersibility of the migrating particles 241 is reduced, the light transmittance of the light diffusion layer 240 may be reduced.

A privacy protection film according to an embodiment of the present invention provides a switchable privacy protection film capable of selectively adjusting a viewing angle according to application of an electrical signal. Specifically, the privacy protection film according to an embodiment of the present invention can provide a security mode by providing a narrow viewing angle so that the user can see the image displayed on the display device, and the image can be seen by other people around. A sharing mode that provides a wide viewing angle can be provided. The privacy protection film according to an embodiment of the present invention uses a light control layer including a light transmission area and a light blocking area and a light diffusion layer including electrophoretic particles, so that the security mode and the sharing mode can be freely switched as needed. A privacy protection film may be provided.

Reference is made to FIGS. 3A and 3B to explain how the privacy protection film according to an embodiment of the present invention provides a security mode and a sharing mode.

3a and 3b are cross-sectional views illustrating a security mode and a sharing mode when driving a privacy protection film according to an embodiment of the present invention. Specifically, FIG. 3A is a diagram for explaining a security mode, and FIG. 3B is a diagram for explaining a sharing mode.

First, in the case of the privacy protection film 200 shown in FIG. 2A , a case in which voltage is not applied to the first electrode 250 and the second electrode 260 is illustrated. When voltage is not applied to the first electrode 250 and the second electrode 260, the electrophoretic particles 241 are dispersed in the solvent 242 in the light diffusion layer 240, and the electrophoretic particles 241 Overall light transmittance of the privacy protection film 200 may decrease.

When DC voltages of different potentials are applied to the first electrode and the second electrode, an electric field is formed between the first electrode and the second electrode, and the electrophoretic particles, which are charged particles with electric charges, move in the solvent by the Coulomb force. will move More specifically, when a voltage is applied to the first electrode and the second electrode, the electrophoretic particles move to the electrode to which a potential opposite to that of the electrophoretic particle is applied.

Referring to FIG. 3A , the privacy protection film 300a is operated in a security mode. In the security mode, the electrophoretic particles 341a are disposed to be attached to the first electrode 250 . For example, when the electrophoretic particle 341a has a negative charge, a positive voltage may be applied to the first electrode 250 and a negative voltage may be applied to the second electrode 260. . At this time, the electrophoretic particles 341a move to the first electrode 250 disposed on the light blocking region 232 of the light control layer 230 and are attached to the surface of the first electrode 250 .

When the electrophoretic particles 341a are attached to the surface of the first electrode 250, the light passing through the light control layer 230 can pass through the light diffusion layer 240 without colliding with the electrophoretic particles 241. At this time, the viewing angle of the light is limited by the light transmission region 231 and the light blocking region 232 of the light control layer 230 . Specifically, referring to FIG. 3A , light incident at a viewing angle exceeding a certain angle Θv (dotted line) is blocked by the light blocking region 232, and light incident at a viewing angle less than a certain angle Θv ( The solid line) passes through the light control layer 230 through the light transmission region 231 without being blocked by the light blocking region 232 . Meanwhile, the viewing angle is determined by geometrical parameters such as height “H”, width “W”, and spacing “P” of the light blocking region 232 of the light control layer 230 .

Therefore, in the security mode, the electrophoretic particles 341a are disposed on the first electrode 250, and the light control layer 230 including the light transmission area 231 and the light blocking area 232 has a specific viewing angle or more. In , the light transmittance is greatly reduced, thereby providing a security mode. For example, the light blocking region 232 may have a height of 100 μm, a width of 15 μm, and an interval of 45 μm. At this time, the light transmittance of the privacy protection film 300a at a viewing angle of 45° may be 5% or less, more preferably 3% or less.

Referring to Figure 3b, the privacy protection film (300b) is operated in a sharing mode. In the sharing mode, the electrophoretic particles 341b are disposed to be attached to the second electrode 260 . For example, when the electrophoretic particles 341b have a negative charge, a negative voltage may be applied to the first electrode 250 and a positive voltage may be applied to the second electrode 260. . At this time, the electrophoretic particles 341b move to the second electrode 260 disposed on the second film 220 spaced apart from the light control layer 230 and are attached to the surface of the second electrode 260 . At this time, when the second electrode 260 has a structure disposed on the front surface of the second film 220, the electrophoretic particles 341b are attached to the front surface of the second electrode 260, thereby forming the light control layer 230. It may be arranged in a structure covering the entire top.

When the electrophoretic particles 341b are attached to the surface of the second electrode 260, the light passing through the light control layer 230 passes through the light diffusion layer 240. It collides with the placed electrophoretic particles 341b. The electrophoretic particles 341b included in the privacy protection film 300b according to an embodiment of the present invention include hollow particles, and as a result, the light passing through the light control layer 230 is the electrophoretic particle 341b. It collides with and scatters.

That is, light having a limited viewing angle passing through the light control layer 230 including the light transmission region 231 and the light blocking region 232 is directed to the electrophoretic particles 341b disposed on the front surface of the second electrode 260. By being diffused by the light control layer 230, the viewing angle control effect is nullified. Therefore, in the sharing mode, the electrophoretic particles 341b are disposed on the second electrode 260, and light transmittance at a viewing angle limited by the light control layer can be greatly improved. For example, when the light blocking region 232 has a height of 100 μm, a width of 15 μm, and an interval of 45 μm, the light transmittance of the privacy protection film 300b at a viewing angle of 45° may be 30% or more.

The privacy protection film according to an embodiment of the present invention may provide a switchable privacy protection film capable of selectively adjusting a viewing angle according to application of an electrical signal. Specifically, by using or scattering the light whose viewing angle is controlled by the light control layer including the light transmission area and the light blocking area using the light diffusion layer including electrophoretic particles, the security mode and the sharing mode are set as necessary. can be freely switched.

In addition, compared to a privacy protection film according to an embodiment of the present invention and a switchable privacy protection device using an electro-chromic material, the side transmittance in the security mode state is poor or the light absorption ability is poor. , and has excellent mode conversion performance and driving stability.

4 is a cross-sectional view for explaining a privacy protection film according to another embodiment of the present invention. Referring to FIG. 4 , the privacy protection film 400 according to another embodiment of the present invention includes a first film 210, a second film 220, a first electrode 450, a second electrode 260, a light A control layer 230 and a light diffusion layer 240 including dispersed electrophoretic particles 241 are included. Since the privacy protection film 400 shown in FIG. 4 is substantially the same as the privacy protection film 200 shown in FIG. 2A except for the shape of the first electrode, redundant description will be omitted.

Referring to FIG. 4 , the first electrode 450 is disposed on the light blocking region 232 of the light control layer 230, and the width d1 of the first electrode 450 is the width of the light blocking region 232. It is smaller than the width (W). For this reason, both ends of the first electrode 450 may be positioned inside than both ends of the light blocking region 232 to form a step difference.

Since the first electrode 450 disposed on the light blocking region 232 has a smaller width than the light blocking region 232, light transmittance is improved even at a viewing angle controlled by the light control layer 230 in the security mode. It is possible to prevent a problem in which the performance of the security mode is degraded. That is, in the security mode, scattering of a part of light to be blocked by the electrophoretic particles 241 disposed on the side surface of the first electrode 450 can be suppressed.

In order to explain the improved performance of the privacy protection film 400 according to FIG. 4, reference is made to FIGS. 5A and 5B.

5A and 5B are cross-sectional views illustrating performance improvement in a security mode according to a change in electrode width. Specifically, FIG. 5A is a cross-sectional view illustrating the propagation of light in the security mode when the width of the first electrode 250 and the width of the light blocking region 232 are the same, and FIG. When the width of the blocking region 232 is smaller than that, it is a cross-sectional view representing the propagation of light in the security mode.

Referring to FIG. 5A , when a security mode is driven by applying voltage to the first electrode 250 and the second electrode 260, an electric field is generated between the first electrode 250 and the second electrode 260. . At this time, an electric field is also generated on the side surface of the first electrode 250, so that some of the electrophoretic particles 541a may be disposed on the side surface of the first electrode 250. At this time, some of the light blocked by the light blocking region 232 and the electrode disposed on the light blocking region 232 collides with the electrophoretic particles 541a disposed on the side of the first electrode 250 and is not blocked. A phenomenon of scattering and exiting the upper part of the privacy protection film may occur. That is, the light transmittance is increased due to light scattering even at a viewing angle limited in the security mode by the electrophoretic particles 541a disposed on the side of the first electrode 250, and as a result, the function of the light control layer 230 is reduced. Deterioration problems may occur.

In contrast, referring to FIG. 5B , the first electrode 450 of the privacy protection film is formed to have a width smaller than that of the light blocking region 232 so that there is a gap between the first electrode 450 and the light blocking region 232. A step difference occurs in Even when the security mode is operated and an electric field is generated on the side of the first electrode 450 and the electrophoretic particle 541b is disposed on the side of the first electrode 450, the electrophoretic particle 541b does not interact with the first electrode 450 and the light. It may be disposed in the stepped portion between the blocking regions 232 and is not disposed out of the light blocking region 232 . Compared to FIG. 5A, in the privacy protection film shown in FIG. 5B, since the light blocked by the light control layer 230 does not collide with the protruding electrophoretic particles 541b, the unexpected light at the viewing angle limited in the security mode Scattering can be suppressed. Therefore, degradation of the function of the light control layer 230 can be minimized.

Referring to FIG. 4 , a distance d2 between one end of the first electrode 450 and one end of the light blocking region 232 may range from 0.2 μm to 3.0 μm. The distance d2 between one end of the first electrode 450 and one end of the light blocking region 232 is set to about the diameter of at least one electrophoretic particle 241, so that the electrophoretic particle 241 can reach the first electrode 450. ), a space for accommodating the electrophoretic particles 241 may be formed so that the electrophoretic particles 241 protrude from the side surfaces of the light blocking region 232 and do not collide with light at a limited viewing angle. .

Hereinafter, the effects of the present invention described above will be described in more detail through Examples and Comparative Examples. However, the following examples are for illustration of the present invention, and the scope of the present invention is not limited by the following examples.

Example One

After dissolving 2.0 grams of polyester (ET6000, manufactured by SK Chemicals) as a binder resin in 45.0 grams of methylene chloride, 1.5 grams of SiO2 hollow particles with a size of 2.0 μm were mixed, and then 0.3 mm zirconia beads were filled with 60 volume percent. After being put in a wide mouth bottle, dispersion was performed for 12 hours to prepare a translucent suspension dispersion having an average particle size. After separating the zirconia beads from the suspension dispersion prepared as described above, 0.01 g of cetyltrimethyl ammonium bromide reaction (CTAB), 0.15 g of polyisobutylene succinimide, and 280.0 methylene chloride were used as charge control agents. gram was added to prepare a mixed solution.

Electrophoretic particles were prepared by dropping the mixed solution onto 600.0 grams of an isoparaffinic solvent (Isopar G). After concentration by distillation of methylene chloride and isoparaffin solvent at 70 ° C., washing by centrifugation, an electrophoretic particle suspension was prepared using Isopar G to have a concentration of 0.2% by weight.

A lower film including a light blocking region having a width of 15 μm, a pitch of 45 μm, and a height of 150 μm is prepared, and indium tin oxide (ITO) is deposited and patterned to a thickness of 500 Å on top of the light blocking region to form a first electrode. do. A substrate having a sheet resistance of 15 Ω/□ on which indium tin oxide is deposited on the first electrode is used as the second electrode so that the distance between the first and second electrodes is 100 μm, and then the prepared electrophoretic particle suspension is By injecting, a privacy protection film was prepared.

Example 2

A privacy protection film was prepared in the same manner as in Example 1, except that an electrophoretic particle suspension was prepared to have a concentration of 0.05% by weight and injected between the first electrode and the second electrode.

Example 3

A privacy protection film was prepared in the same manner as in Example 1, except that an electrophoretic particle suspension was prepared to have a concentration of 0.1% by weight and injected between the first electrode and the second electrode.

Example 4

A privacy protection film was prepared in the same manner as in Example 1, except that an electrophoretic particle suspension was prepared to have a concentration of 0.4% by weight and injected between the first electrode and the second electrode.

comparative example One

A privacy protection film including a light blocking region having a width of 15 μm, a pitch of 45 μm, and a height of 150 μm was prepared. The privacy protection film according to Comparative Example 1 has a structure shown in FIG. 1A.

comparative example 2

A microstructure layer including a plurality of grooves having a width of 15 μm, a pitch of 45 μm, and a height of 150 μm is formed on a PET film using an acrylate resin, and then the first electrode is formed with PEDOT/PSS inside the grooves of the microstructure layer. was formed. Thereafter, an electrochromic material (eg, including PEDOT) was injected into the groove of the microstructure layer and cured. A privacy protection film including an electrochromic material in the microstructure layer was prepared using a substrate having a sheet resistance of 15 Ω/□ on which indium tin oxide was deposited on the microstructure layer as a second electrode. The privacy protection film according to Comparative Example 2 has a structure shown in FIG. 1B.

Experimental Example 1 - Depending on the viewing angle light transmittance measurement

The privacy protection films according to Example 1, Comparative Example 1 and Comparative Example 2 were measured for light transmittance at viewing angles of 0 ° and 45 ° when operating in security mode and sharing mode using Autronics' DMS-803 equipment. In the case of Comparative Example 1, since there is no separate sharing mode, only the security mode was measured.

The measurement results are shown in Table 1.

Example 1 Comparative Example 1 Comparative Example 2 viewing angle security mode share mode security mode share mode security mode share mode 0 57.56% 56.59% 67.27% - 29.7% 37.3% 45 2.31% 33.02% 1.34% - 5.4% 24.1% 80 1.02% 30.99% 0.32% - - -

Referring to Table 1, the privacy protection film according to Example 1 provides a security mode with performance similar to that of Comparative Example 1. In addition, comparing Example 1 and Comparative Example 2, the privacy protection film according to Example 1 using electrophoretic particles is superior to the conventional privacy protection film using electrochromic materials, although they have light blocking areas of the same size. It can be seen that a remarkably excellent light transmittance is exhibited at a viewing angle of 0°. In addition, compared to Comparative Example 2, it can be confirmed that the privacy protection film according to Example 1 has a high light transmittance even at a viewing angle of 45°, that is, from the side, in the case of sharing mode. Referring to Table 1, it can be confirmed that the privacy protection film according to an embodiment of the present invention can be easily switched between a security mode and a sharing mode, and has excellent light transmittance in the sharing mode.

Experimental Example 2 - Evaluation of privacy protection film performance according to the concentration of electrophoretic particles

Using Autronics' DMS-803 equipment, light transmittance was measured at various viewing angles in the sharing mode of the privacy protection films according to Examples 1 to 4. In addition, the light transmittance of the privacy protection film according to Comparative Example 1 was measured at various viewing angles.

The measurement results are shown in FIG. 6 .

Referring to FIG. 6, in the case of Example 1, in which the concentration of electrophoretic particles was 0.2% by weight, the light transmittance was generally high at various viewing angles, indicating that images could be sufficiently recognized at various viewing angles in the sharing mode. can In contrast, Examples 2 and 3, in which the concentrations of the electrophoretic particles were 0.05% by weight and 0.1% by weight, respectively, showed higher light transmittance than Comparative Example 1 at a viewing angle of 35° or more, but lower light transmittance than Example 1. indicates transmittance. Through this, it can be seen that when the concentration of the electrophoretic particles is low, the function of diffusing light in the sharing mode is relatively insufficient.

On the other hand, in the case of Example 4 in which the concentration of the electrophoretic particles is 0.4% by weight, the light transmittance is significantly higher than that of Comparative Example 1 at a viewing angle of 35° or more, but the light transmittance is lower than that of Example 1 at a viewing angle of 0° or more. I was able to confirm that I was lazy. From this, it can be seen that when the concentration of the electrophoretic particles is high, the overall dispersion is lowered and the light transmittance is lowered.

A display device according to an embodiment of the present invention may include a privacy protection film and a display panel. At this time, since the privacy protection film is the same as the privacy protection film shown in FIG. 2a or FIG. 4, a redundant description of the privacy protection film will be omitted.

A display panel means a panel on which display elements for displaying an image are arranged in a display device. As the display panel, for example, various display panels such as an organic light emitting display panel, a liquid crystal display panel, an electrophoretic display panel, and the like can be used.

A privacy protection film is disposed on the display panel. The privacy protection film functions to limit a viewing angle of light emitted from a display panel disposed below.

The display device according to an exemplary embodiment of the present invention includes a privacy protection film capable of selectively adjusting a viewing angle according to application of an electrical signal, so that a security mode and a sharing mode can be set to the user's needs without directly removing the film from the display panel. can be freely switched. In addition, since the privacy protection film included in the display device according to an embodiment of the present invention uses electrophoretic particles, the security mode and the sharing mode are quickly converted and driving stability is excellent, and thus, a stable privacy protection function can be operated. can

An exemplary embodiment of the present invention may be described as follows.

In order to solve the above problems, a privacy protection film according to an embodiment of the present invention includes a light transmission area that transmits light and a light blocking area disposed between the light transmission area to block light in a specific direction. A control layer, a plurality of first electrodes disposed on the light blocking region of the light control layer, a second electrode spaced apart from the plurality of first electrodes at regular intervals, and disposed between the light control layer and the second electrode, electrophoretic particles It includes a light diffusion layer comprising a.

The light transmitting region and the light blocking region may be alternately arranged in one direction perpendicular to the thickness direction and extend in another direction perpendicular to the thickness direction.

The light blocking region may have a height of 80 μm to 120 μm, a width of 15 μm to 20 μm, and an interval of 30 μm to 60 μm.

The light diffusion layer may include a solvent and electrophoretic particles dispersed in the solvent.

The concentration of the electrophoretic particles may be 0.01 wt % to 0.4 wt % based on the entire light diffusion layer.

Electrophoretic particles may include hollow particles, a charge control agent (CCA), a binder resin, and a surfactant.

Electrophoretic particles may have a structure in which hollow particles form a core, a charge control agent surrounds the hollow particles, and a surfactant surrounds the charge control agent.

The hollow particles may be organic particles, inorganic particles, or organic-inorganic composite particles having a diameter of 0.1 μm to 5 μm and containing air in the hollow portion.

Electrophoretic particles may be disposed on a plurality of first electrodes or second electrodes.

A width of each of the plurality of first electrodes may be smaller than a width of the light blocking region.

A distance between one end of the plurality of first electrodes and one end of the light blocking region may be 0.2 μm to 3.0 μm.

When a first DC voltage is applied to the plurality of first electrodes and the second electrode, the electrophoretic particles are disposed on the plurality of first electrodes, so that the light transmittance of the privacy protection film at a viewing angle of 45° is 5% or less, and , When the second DC voltage is applied to the plurality of first electrodes and the second electrode, the electrophoretic particles are disposed on the second electrode, and the light transmittance of the privacy protection film at a viewing angle of 45 ° may be 30% or more. .

In order to solve the above problems, a display device according to an embodiment of the present invention includes a display panel and a privacy protection film on one surface of the display panel, wherein the privacy protection film is repeated in one direction perpendicular to the thickness direction. A first film including a light transmission area and a light blocking area, a second film facing each other at a predetermined distance from the first film, a first electrode disposed on the light blocking area of the first film, and a front surface of the second film It includes a second electrode disposed on and electrophoretic particles disposed between the first film and the second film.

Electrophoretic particles may include hollow particles, a charge control agent (CCA), a binder resin, and a surfactant.

Electrophoretic particles may be disposed on the first electrode or the second electrode according to a potential difference between voltages applied to the first electrode and the second electrode.

The light blocking region may have a shape extending in another direction perpendicular to the thickness direction, and the light blocking region may have a height of 80 μm to 120 μm, a width of 15 μm to 20 μm, and an interval of 30 μm to 60 μm.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and may be variously modified without departing from the technical spirit of the present invention. . Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be construed according to the claims below, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

200: privacy protection film
210: first film
220: second film
230: light control layer
231 light transmission area
232 light blocking area
240, 340a, 340b: light diffusion layer
241, 341a, 341b: electrophoretic particles
242 solvent
250, 450: first electrode
260: second electrode

Claims (16)

a light control layer including a light transmission area that transmits light and a light blocking area disposed between the light transmission area and blocking light in a specific direction;
a plurality of first electrodes disposed on the light blocking region of the light control layer;
a second electrode spaced apart from the plurality of first electrodes at regular intervals; and
a light diffusion layer disposed between the light control layer and the second electrode and including electrophoretic particles;
When a first DC voltage is applied to the plurality of first electrodes and the second electrode, the electrophoretic particles are disposed on the plurality of first electrodes, and the light transmittance at a viewing angle of 45° is 5% or less;
When a second DC voltage is applied to the plurality of first electrodes and the second electrode, the electrophoretic particles are disposed on the second electrode, and the light transmittance at a viewing angle of 45 ° is 30% or more, the privacy protection film . According to claim 1,
The privacy protection film of claim 1 , wherein the light transmitting region and the light blocking region are alternately arranged in one direction perpendicular to the thickness direction and extend in another direction perpendicular to the thickness direction. According to claim 2,
Wherein the light blocking region has a height of 80 μm to 120 μm, a width of 15 μm to 20 μm, and an interval of 30 μm to 60 μm. According to claim 1,
The privacy protection film of claim 1, wherein the light diffusion layer includes a solvent and the electrophoretic particles dispersed in the solvent. According to claim 4,
The concentration of the electrophoretic particles is 0.01% to 0.4% by weight based on the total light diffusion layer, the privacy protection film. According to claim 1,
Wherein the electrophoretic particles include hollow particles, a charge control agent (CCA), a binder resin and a surfactant. According to claim 6,
Wherein the electrophoretic particles have a structure in which the hollow particles form a core, the charge control agent surrounds the hollow particles, and the surfactant surrounds the charge control agent. According to claim 6,
The hollow particles have a diameter of 0.1 μm to 5 μm and are organic particles, inorganic particles or organic-inorganic composite particles containing air in the hollow portion, privacy protection film. According to claim 1,
The privacy protection film, wherein the electrophoretic particles are disposed on the plurality of first electrodes or the second electrodes. According to claim 1,
The privacy protection film of claim 1 , wherein a width of each of the plurality of first electrodes is smaller than a width of the light blocking region. According to claim 10,
A distance between one end of the plurality of first electrodes and one end of the light blocking region is 0.2 μm to 3.0 μm, the privacy protection film. delete display panel; and
A privacy protection film on one surface of the display panel;
The privacy protection film is:
a first film including a light transmission area and a light blocking area repeated in one direction perpendicular to the thickness direction;
a second film facing each other at a predetermined interval from the first film;
a first electrode disposed on a light blocking region of the first film;
a second electrode disposed on the front surface of the second film; and
Including electrophoretic particles disposed between the first film and the second film,
When a first DC voltage is applied to the plurality of first electrodes and the second electrode, the electrophoretic particles are disposed on the plurality of first electrodes, and the light transmittance of the privacy protection film at a viewing angle of 45° is less than 5%,
When a second DC voltage is applied to the plurality of first and second electrodes, the electrophoretic particles are disposed on the second electrode, so that the light transmittance of the privacy protection film at a viewing angle of 45° is 30%. Ideal, display device. According to claim 13,
The display device of claim 1 , wherein the electrophoretic particles include hollow particles, a charge control agent (CCA), a binder resin, and a surfactant. According to claim 13,
wherein the electrophoretic particles are disposed on the first electrode or the second electrode according to a potential difference between voltages applied to the first electrode and the second electrode. According to claim 13,
The light blocking region has a shape extending in another direction perpendicular to the thickness direction,
The light blocking region has a height of 80 μm to 120 μm, a width of 15 μm to 20 μm, and an interval of 30 μm to 60 μm.

Images