WO2020009443A1 - Optical modulation element - Google Patents

Abstract

The present application relates to an optical modulation element and a use thereof, and improves the surface waviness of a substrate film, which is caused by a spacer, so as to suppress a surface waviness phenomenon observed when the surface reflection is visually observed. The optical modulation element can be applied to various flexible display devices, thereby improving the quality of these products.

Description

Optical modulation device

The present application relates to a light modulation device and its use.

This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0076481 dated July 02, 2018 and Korean Patent Application No. 10-2019-0079555 dated July 02, 2019. All contents disclosed are included as part of this specification.

In Patent Document 1 (Korean Patent Publication No. 1775332), an optical modulator such as a liquid crystal cell may generally include a spacer to maintain a cell gap between an upper base film and a lower base film. In addition, when the optical modulator is to be applied to a flexible display device that is bent, such as eyewear, a flexible base film may be required as the upper base film and the lower base film.

However, when fabricating an optical modulation device by applying a flexible base film, a problem occurs in that bending occurs on the surface of the upper base film and the lower base film due to the difference in the degree of being pressed by the portion where the spacer is present and the portion that does not exist. Can be. When the surface of the optical modulation device is observed by reflecting light due to the surface curvature, the surface curvature may be confirmed, which may cause a problem of deterioration of product quality. Therefore, there is a need for a light modulator that can improve the surface curvature of the base film caused by the spacer.

An object of the present application is to provide a light modulation device capable of suppressing surface waviness phenomenon when observing surface reflection luminousness by improving surface curvature of a base film caused by a spacer.

The present application relates to a light modulation device. The light modulator may include a first base film and a second base film disposed to face each other. The light modulator may include a light modulator layer disposed between the first base film and the second base film. The light modulation layer may include a spacer. The optical modulator may further include a buffer layer disposed outside the base film of at least one of the first base film and the second base film. The buffer layer may be formed outside the first base film, outside the second base film, or outside each of the first base film and the second base film.

As used herein, the term "light modulation layer" may refer to a functional layer capable of varying light transmittance, reflectance, or haze depending on whether external energy is applied.

As used herein, the term "buffer layer" may refer to a functional layer capable of alleviating surface curvature of a base film caused by a spacer.

As used herein, the term "inner side" means the side facing the light modulation layer in the optical modulation element, and the "outer side" means the opposite side of the side facing the light modulation layer in the optical modulation element.

1 exemplarily shows a light modulation device of the present application. The optical modulator of FIG. 1 includes a spacer 31 disposed between the first base film 10 and the second base film 20, and the first base film 10 and the second base film 20, which are disposed to face each other. An optical modulation device including an optical modulation layer 30 including and a buffer layer 40 disposed on the outside of each of the first base film 10 and the second base film 20 is exemplarily illustrated.

The light modulation layer may include a spacer. The spacer may function as a cell gap holding member that maintains a gap between the first base film and the second base film. The spacer may be a ball spacer or a column spacer. The spacer may include at least one selected from a polymer material, a carbon material, an oxide material, and a composite material thereof. The material of the ball spacer may be specifically silica, polysiloxane polymer or divinylbenzene copolymer. The material of the column spacer may specifically be UV curable acrylate or epoxy. In one example, the spacer may be a black spacer. The black ball spacers can comprise carbon black and the black column spacers can also include carbon black.

The size of the spacer may be appropriately adjusted in consideration of the gap (cell gap) between the first base film and the second base film. The size of the spacer may mean a particle diameter in the case of a ball spacer, and may mean a height in the case of a column spacer. The size of the spacer can be, for example, 1 μm to 50 μm. Specifically, the size of the spacer may be 1 μm or more, 2 μm or more, or 3 μm or more, and 50 μm or less, 40 μm or less, 30 μm or less, or 20 μm or less.

The light modulation layer may include a plurality of spacers. In this case, the plurality of spacers may be present in the light modulation layer spaced apart from each other. In the present specification, the "spaced apart" may mean that the spaced apart state exists at predetermined intervals.

In the light modulation layer, the first base film and / or the second base film may have surface curvature due to the difference between the degree of being pressed by the region where the spacer is present and the region where the spacer is not present. The optical modulation device of the present application may improve the degree of recognition of the surface curvature by forming a buffer layer on the outside of the first base film and / or the second base film, and thus observe surface curvature when observing the surface reflection. This phenomenon can be suppressed.

Hereinafter, the buffer layer will be described in detail. As shown in FIG. 1, the buffer layer 40 may sequentially include a buffer film 42 and an adhesive layer 41.

Both surfaces of the buffer film may be flat. As the buffer film, a flexible film having optical transparency can be used. For example, an optically transparent plastic film can be used as a buffer film. Specifically, the plastic film may include a cellulose film such as a diacetyl cellulose (DAC) or a triacetyl cellulose (TAC) film; COP (cyclo olefin copolymer) films, such as a norbornene derivative resin film; Acrylic films such as poly (methyl methacrylate) films; polycarbonate (PC) films; olefin films such as polyethylene (PE) or polypropylene (PP) films; polyvinyl alcohol (PVA) films; poly ether sulfone (PES) films; PEEK (polyetheretherketone) film; PEI (polyetherimide) film; PEN (polyethylenenaphthatlate) film; polyester film such as PET (polyethyleneterephtalate) film, etc .; PI (polyimide) film; PSF (polysulfone) film; PAR (polyarylate) film or fluororesin film This may be exemplified, and in general, a cellulose film, a polyester film or an acrylic film may be used. Preferably, a TAC film or a PC film may be used, but may be appropriately selected in consideration of the purpose of the present application.

The buffer film may have a thickness of 50 μm or more. This thickness range may be more advantageous for improving the surface curvature of the base film. The upper limit of the thickness of the buffer film may be, for example, 1000 μm or less. Specifically, the thickness of the buffer film may be 50 μm or more, 100 μm or more or 150 μm or more, and 1000 μm or less, 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, or 550 μm or less. Depending on the material of the buffer film, the thickness range may also be appropriately selected. In one example, when using a PC film as the buffer film, the thickness range may be 200 μm to 800 μm or 400 μm to 600 μm. In another example, when using a TAC film as the buffer film, the thickness range may be 50 μm to 350 μm or 150 μm to 250 μm.

The adhesive layer may have a flat surface facing the buffer film and a surface facing the light modulation layer may have surface curvature. Specifically, the pressure-sensitive adhesive layer is attached to the curvature generated on the surface of the first base film and / or the second base film of the optical modulation element, corresponding to the surface curvature of the first base film and / or the second base film The face has a surface curvature and the opposite side thereof may be formed flat. For this reason, the buffer film is formed on a flat surface of the adhesive layer, both surfaces may be flat.

The adhesive layer may include an OCA (Optically Clear Adhesive) adhesive. The OCA pressure-sensitive adhesive may be a pressure-sensitive adhesive, for example, known pressure-sensitive adhesives such as acrylic pressure sensitive adhesive, silicone pressure sensitive adhesive, rubber pressure sensitive adhesive, urethane pressure sensitive adhesive can be used without particular limitation. The OCA adhesive is a concept that is distinguished from an OCR (Optically Clear Resin) adhesive provided in a liquid phase, and may be mainly provided in a solid, semi-solid or elastic state. The pressure-sensitive adhesive may be a kind of adhesive, and may mean a material having a function of adhering to the adherend even with a slight pressure applied to a portion of the adhesive without using water, solvent heat, or the like.

In order to secure suitable surface properties, the thickness of the adhesive layer can be controlled. For example, the ratio (T1 / T2) of the thickness T1 of the pressure-sensitive adhesive layer and the thickness T2 of the base film (that is, the base film to which the pressure-sensitive adhesive layer is attached) may be in a range of about 0.1 to 4, inclusive. have. The ratio T1 / T2 is in another example about 0.2 or more, about 0.3 or more, or about 0.4 or more, about 3.5 or less, about 3 or less, about 2.5 or less, about 2 or less, about 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, or about 1 or less may be sufficient.

Meanwhile, the ratio (T3 / T1) of the thickness T1 of the adhesive layer and the thickness T3 of the buffer film may be in the range of about 0.25 to 50. The ratio (T3 / T1) is in another example about 0.5 or more, about 0.75 or more, about 1 or more, about 1.25 or more, about 1.5 or more, about 1.75 or more, about 2 or more, about 2.25 or more, or about 2.5 or more, or about 40 Or about 30 or less, about 20 or less, about 10 or less, about 9 or less, about 8 or less, about 7 or less, about 6 or less, or about 5 or less.

In such a range, it is possible to efficiently solve the surface bending problem of the optical modulation device, in which the cell gap is secured to an appropriate level while the optical modulation device, in particular, the thin base film is applied.

FIG. 2 is an enlarged view of a portion of the optical modulator for explaining surface curvature caused by the spacer. FIG. As described above, at least one base film of the first base film 10 and the second base film 20 may have surface curvature caused by the spacer 31. The base film having surface curvature may have surface curvature on both surfaces.

The surface curvature may have a convex portion in the region of the base film corresponding to the region where the spacer exists and have a concave portion in the region of the base film corresponding to the region where the spacer does not exist.

In one example, the height difference (B of FIG. 2) between the most convex region and the most concave region in the surface curvature of the base film may be 0.1 μm to 1 μm. The height difference B may be specifically 0.2 μm to 0.8 μm or 0.4 μm to 0.6 μm. This height difference may depend on the size of the spacer or the flexibility of the base film.

As shown in FIG. 2, due to the surface bending of the base film caused by the spacer, the light modulation layer 30 may also have surface bending. Like the base film, the light modulation layer may have a convex portion in the region where the spacer is present and may have a concave portion in the region where the spacer does not exist.

In one example, the height difference (A of FIG. 2) between the most convex region and the most concave region in the surface curvature of the light modulation layer may be 0.1 μm to 1 μm. The height difference A may be specifically 0.2 μm to 0.8 μm or 0.4 μm to 0.6 μm.

As shown in FIG. 2, in the state where the adhesive layer is applied to the substrate film having surface curvature, one surface of the adhesive layer 41 may also have surface curvature by surface curvature of the substrate film caused by the spacer. The adhesive layer may have a concave portion in a region corresponding to a region where a spacer exists and may have a convex portion in a region corresponding to a region where the spacer does not exist.

In one example, the thickness of the adhesive layer may be 20 μm or more. This thickness range may be more advantageous for improving the surface curvature of the base film. Specifically, the adhesive layer may have a thickness of 20 μm or more, 50 μm or more, or 80 μm or more, and may be 200 μm or less, 150 μm or less, or 120 μm or less. The thickness of the adhesive layer may mean the thickness of the adhesive layer itself before the adhesive layer is applied to the base film having the surface curvature.

In one example, with the adhesive layer applied to the base film having the surface curvature, the difference between the maximum value and the minimum value of the thickness of the adhesive layer (CD in FIG. 2) is the most convex area and the most concave in the surface curvature of the base film. It may have the same value as the height difference (B) of the region. Therefore, the maximum value and the minimum value difference (C-D) of the thickness of the adhesive layer may be 0.1 μm to 1 μm, 0.2 μm to 0.8 μm, or 0.4 μm to 0.6 μm. In the above, the maximum value (C) and the minimum value (D) of the thickness of the pressure-sensitive adhesive layer, respectively, in the state where the pressure-sensitive adhesive layer is applied to the base film having the surface curvature, and the maximum value of the thickness measured based on the outer surface having the flat surface, It may mean a minimum value.

In the state where the adhesive layer is applied to the base film having the surface curvature, the maximum value (C) of the thickness of the adhesive layer may be a value obtained by adding the height difference due to the surface curvature in the thickness of the adhesive layer itself. In one example, when the thickness of the adhesive layer itself is 20 μm, the maximum value C of the thickness of the adhesive layer may be about 20 μm to 21 μm.

In the state where the adhesive layer is applied to the base film having the surface curvature, the minimum value (D) of the thickness of the adhesive layer may be a value obtained by subtracting the height difference due to the surface curvature from the thickness of the adhesive layer itself. In one example, when the thickness of the adhesive layer itself is 20 μm, the maximum value C of the thickness of the adhesive layer may be about 19 μm to 20 μm.

The adhesive layer may be attached to at least one base film of the first base film and the second base film in a cured state. Curing of the adhesive layer may be performed by applying an appropriate energy, for example, heat and / or light irradiation. In one example, the adhesive layer may be prepared in a form in which a release film is present on each side. After removing the release film on one side of the adhesive layer and laminating the adhesive layer on the outside of the base film, the buffer layer may be formed by removing the release film on the other side of the adhesive layer and laminating the buffer film on the adhesive layer.

At least one base film of the first base film and the second base film may be a flexible film. Specifically, any one of the first base film and the second base film may be a flexible film or both may be a flexible film.

In the present specification, the flexible film may mean a film having flexibility. As the flexible film, a flexible film having optical transparency may be used. For example, an optically transparent plastic film may be used as the first base film and / or the second base film. Specifically, the plastic film may include a cellulose film or sheet such as a diacetyl cellulose (DAC) or a triacetyl cellulose (TAC) film or sheet; Cyclo olefin copolymer (COP) films or sheets such as norbornene derivative resin films or sheets; Acrylic film or sheet such as poly (methyl methacrylate) film or sheet; polycarbonate (PC) film or sheet; olefin film or sheet such as polyethylene (PE) or polypropylene (PP) film or sheet; polyvinyl alcohol (PVA) film Or sheets; poly ether sulfone (PES) films or sheets; polyetheretherketone (PEEK) films or sheets; polyetherimide (PEI) films or sheets; polyethylenenaphthatlate (PEN) films or sheets; polyester films such as polyethyleneterephtalate (PET) films or sheets or Sheets; polyimide (PI) films or sheets; polysulfone (PSF) films or sheets; polyarylate (PAR) films or sheets or fluororesin films or sheets, and the like, and generally cellulose films or sheets, polyester films or Sheets or acrylic films or sheets may be used, preferably PET films or sheets may be used. However, it may be appropriately selected in consideration of the purpose of the present application.

The flexible film may be advantageous in terms of flexibility as the radius of curvature is small. In one example, the radius of curvature of the flexible film can be adjusted to a level of about 1 mm to 10 mm if necessary. The radius of curvature of the optical modulation device to which the flexible film is applied may be about 40 mm to about 50 mm. The radius of curvature of the optical modulation element is somewhat large because the cracking of the electrode layer or the adhesion of the sealant that maintains the cell gap can be considered. The radius of curvature of the flexible display device to which the optical modulator is applied may be about 50 mm to about 200 mm. The radius of curvature of the flexible film, the optical modulation element, or the flexible display device may be appropriately changed in consideration of the shape of the final product.

The ratio (T4 / T5) of the thickness (T4) of the first and / or second base film as described above and the gap (that is, the cell gap) T5 between the opposing first and second base films is about It may be in the range of 1 to 100. In another example, the ratio T4 / T5 may be about 1, about 2 or more, or about 3 or more, or about 90 or less, about 80 or less, about 70 or less, about 60 or less, about 50 or less, or about 40 or less. have.

In the above state, the thickness T4 of the base film may be in a range of about 20 μm to 200 μm in one example. In another example, the thickness may be about 30 μm or more, about 40 μm or more, or about 50 μm or more, or about 190 μm or less, about 180 μm or less, about 170 μm or less, about 160 μm or less, or about 150 μm or less.

The thickness T4 of the base film may be at least the thickness of the base film having the electrode layer attached thereto.

By controlling the thickness of such a base film, it is possible to provide a light modulation element that is thin and excellent in flexibility while ensuring the desired optical performance. You can prevent it.

A transparent conductive layer may be used as the first electrode layer and / or the second electrode layer. For example, the first electrode layer and / or the second electrode layer may be formed by terminating a metal oxide such as a conductive polymer, a conductive metal, a conductive nanowire, or indium tin oxide (ITO). The thickness of the first electrode layer and / or the second electrode layer may be 15 nm to 25 nm, respectively.

In one example, the optical modulator may further include an alignment layer (not shown) inside the first base film and / or the second base film. Specifically, the alignment layer may be present inside the first electrode layer and / or the second electrode layer.

As described below, the alignment layer may have an alignment force capable of controlling an initial alignment state of the liquid crystal compound when the light modulation layer includes a liquid crystal compound as a light modulation material. The alignment layer may be a vertical alignment layer or a horizontal alignment layer. When the light modulator includes a first alignment film inside the first base film and a second alignment film inside the second base film, both the first alignment film and the second alignment film are vertical alignment films, or both horizontal alignment films, Alternatively, one may be a vertical alignment layer and one may be a horizontal alignment layer. As the alignment layer, an alignment layer known to be capable of exhibiting alignment characteristics by a non-contact method such as irradiation of linearly polarized light including a contact alignment layer or a photoalignment layer compound, such as a rubbing alignment layer, may be used.

The optical modulation device of the present application may vary transmittance, reflectance, or haze depending on whether external energy is applied to the light modulation layer, for example, voltage. The range of the variable transmittance, reflectance or haze can be appropriately controlled according to the use of the light modulator.

The light modulation layer may include a light modulation material. The light modulation material may be included in a region where no spacer exists in the light modulation layer. Examples of the light modulator may include a liquid crystal compound. As the liquid crystal compound, a liquid crystal compound whose orientation direction may be changed by applying an external voltage may be used without particular limitation. As the liquid crystal, for example, a smectic liquid crystal, a nematic liquid crystal or a cholesteric liquid crystal may be used. In addition, the liquid crystal may be, for example, a compound having no polymerizable group or a crosslinkable group so that the orientation direction thereof may be changed by application of an external voltage.

The light modulation layer may further include an anisotropic dye. The anisotropic dye may contribute to the variable transmittance by improving the light blocking rate of the light modulator. As used herein, the term "dye" may refer to a material capable of intensively absorbing and / or modifying light in at least part or the entire range within the visible light region, for example, in the 400 nm to 700 nm wavelength range. In addition, in the present specification, the term "anisotropic dye" may mean a material capable of anisotropic absorption of light in at least part or the entire range of the visible light region. As the anisotropic dye, for example, a known dye known to have a property that can be aligned according to the alignment state of the liquid crystal may be selected and used, for example, a black dye may be used. Such black dyes are known as, for example, azo dyes or anthraquinone dyes, but are not limited thereto.

The light modulator of the present application may further include a functional layer. The functional layer may be disposed outside the buffer layer. 3 exemplarily illustrates a light modulation device in which the functional layer 50 is disposed outside the buffer layer 40, for example, the buffer film 41. The optical modulation device of the present application can reinforce various functions by further disposing a functional layer on the outside of the buffer layer.

The type of the functional layer may be appropriately selected in consideration of the function to be reinforced in the optical modulation device. In one example, the functional layer is an anti-fog layer, a self-healing layer, an anti-reflection layer, an anti-finger layer, an anti An anti-fouling layer, an anti-glare layer, a mirror layer, or a hardness enhancement layer may be included. The hardness improving layer is also commonly referred to in the art as a "hard coating layer".

Materials and forming methods for forming the functional layer can be selected appropriately known in the art. For example, the functional layer may be formed by separately preparing a functional layer and adhering to the outside of the buffer layer, coating the functional layer composition on the outside of the buffer layer, or depositing a functional layer material on the buffer layer.

The present application also relates to the use of the optical modulation device. Exemplary light modulators can improve the quality of the product by reducing the reflection of the light by suppressing the surface curvature of the base film caused by the spacer.

In one example, the light modulation device may be applied to the flexible display device. Examples of such a flexible device may be a curved, bendable, foldable, or rollable display device.

The flexible display device may include eyewear such as sunglasses, AR (Argumented Reality) or VR (Virtual Reality); Smart windows for exterior walls of buildings; Alternatively, a vehicle sunroof, a front door window, a rear door window, a backlight, a windshield, and the like can be exemplified.

When the flexible display device is eyewear, the structure of the eyewear is not particularly limited. That is, the light modulator may be included and applied to the left eye and / or right eye lens of a known eyewear structure.

For example, the eyewear includes a left eye lens and a right eye lens; And a frame supporting the left eye lens and the right eye lens. In the eyewear, the left eye lens and the right eye lens may each include the optical modulator. Such a lens may include only the optical modulator or other configuration.

The present application can suppress the surface waviness phenomenon when observing the surface reflection luminous by improving the surface curvature of the base film caused by the spacer. Such an optical modulation device may be applied to various flexible display devices to improve product quality.

1 exemplarily shows a light modulation device of the present application.

2 is an enlarged view of a part of an optical modulator for explaining surface curvature.

3 exemplarily shows a light modulation device of the present application.

4 exemplarily shows a light modulator of Comparative Example 1. FIG.

5 is a surface curvature evaluation image of Comparative Example 1.

6 to 8 are surface bending evaluation images of Examples 1 to 3, respectively.

9 is a surface curvature evaluation image of Comparative Example 2.

Hereinafter, the present application will be described in detail with reference to Examples, but the scope of the present application is not limited by the following Examples.

Example 1

As the optical modulation device of Example 1, an optical modulation device having a lens shape of eyewear was manufactured. Specifically, a PC-ITO film (Teijin) having a total thickness of 100 μm, in which an ITO layer was deposited on a PC film, was prepared as a film in which electrode layers were formed on the first and second base films, respectively. A light modulation layer was formed by coating a composition including a liquid crystal compound (MDA-16-1235, Merck) and a ball spacer (KBN-512, Sekisui) having a particle diameter of 12 μm on the electrode layer of the first base film. . At this time, the composition was applied to the inner sealant inner region applied in the shape of the frame of the lens of the eyewear on the PC-ITO film. After laminating the second base film so that the electrode layer of the second base film is in contact with the light modulation layer, the first base film and the first base film may Surface curvatures were formed on both surfaces of the second base film. At this time, the height difference of the most convex area | region and the most concave area | region in the surface curvature of the base film was 0.4 micrometer. The height difference was confirmed by a roughness measurement method using a laser microscope (OLS4000, Olympus). An OCA pressure-sensitive adhesive (V310, LG Chemical Co., Ltd.) having a thickness of 100 μm was laminated on the outside of the second base film. An optical modulation device was manufactured by laminating a 190 μm-thick TAC film (SAF-RT190, UGAM Co., Ltd.) having a thickness of 1 μm coated with an anti-fog layer (functional layer) on a second substrate film through an OCA adhesive. It was. In the light modulator, an anti-fog layer is present at the outermost side.

Example 2

An optical modulation device was manufactured in the same manner as in Example 1, except that a TAC film having a thickness of 190 μm (SHC40T190M, DAICEL Co., Ltd.) having a hard coating layer formed on one surface thereof was formed.

Example 3

The same method as in Example 1, except that a PC film (OM81-5, Polyopt) with a hard coating layer coated on one side was used instead of the TAC film having a thickness of 190 μm coated on one side. An optical modulator was manufactured.

Comparative Example 1

The light modulator shown in FIG. 4 was manufactured in the same manner as in Example 1, except that the adhesive layer, the buffer layer, and the anti-fog layer were not formed outside the second base film.

Comparative Example 2

An optical modulator was manufactured in the same manner as in Comparative Example 1, except that the UV curable acrylate resin (LGC) was coated on the outside of the second substrate film and UV cured at 3 J to form a coating layer having a thickness of 3 μm.

Evaluation Example 1. Evaluation of Surface Waviness

In order to evaluate surface curvature, the surface reflection time was observed about the optical modulation elements of an Example and a comparative example, and the result is shown to FIGS. 5-9. Specifically, in order to prevent the bottom reflection, a black film was positioned below the light modulation element (first base film side), and a fluorescent lamp stand was positioned above the light modulation element (functional layer side). The digital camera was fixed at an angle of about 45 ° with respect to the front of the light modulator and photographed to observe surface reflection.

As shown in Figs. 5 and 9, in Comparative Examples 1 and 2, it was observed that there is a region where the surface does not appear smooth and the height is different between the bright and dark areas inside the optical modulation device. On the other hand, as shown in Figures 6 to 8, Examples 1 to 3 was evaluated that no height difference between the bright area and the dark area inside the optical modulation device was observed and there is no surface curvature. From these experimental results, it can be seen that Examples 1 to 3 with the buffer layer solved the surface bending phenomenon compared to Comparative Examples 1 and 2 without the buffer layer.

<Description of the code>

10: first base film

20: second base film

30: light modulation layer

31: spacer

40: buffer layer

41: adhesive layer

42: buffer film

50: functional layer

Claims (20)

It is arranged between the 1st and 2nd base film and the said 1st and 2nd base film arrange | positioned opposingly, and have a light modulation layer containing a spacer, And a buffer layer disposed outside of at least one of the first and second base films. The ratio (T4 / T5) of the interval T5 between the thickness T4 of the first or second base film and the first and second base films disposed to face each other is in the range of 1 to 30. Light modulation device. The optical modulation device of claim 1, wherein the spacers are spaced apart from each other in the optical modulation layer. The light modulator of claim 1, wherein the buffer layer sequentially includes a buffer film and an adhesive layer. The optical modulator of claim 4, wherein the buffer film is attached to an outer side of at least one of the base film and the base film through the adhesive layer. The light modulator of claim 4, wherein the buffer film has a flat surface. The light modulator of claim 4, wherein the adhesive layer has a flat surface facing the buffer film and a surface facing the light modulation layer. The light modulator of claim 4, wherein the adhesive layer comprises an optically clear adhesive (OCA) adhesive. The light modulator according to claim 4, wherein the ratio (T1 / T2) of the thickness T1 of the pressure-sensitive adhesive layer to the thickness T2 of the first or second base film is in the range of 0.1 to 4. The light modulator according to claim 9, wherein a ratio (T3 / T1) of the thickness T1 of the pressure-sensitive adhesive layer and the thickness T3 of the buffer film is in a range of 0.25 to 50. The optical modulator of claim 1, wherein at least one of the first base film and the second base film has surface curvature by the spacer. 12. The light modulator of claim 11, wherein the surface curvature has a convex portion in a region of the base film corresponding to the region where the spacer exists and a concave portion in the region of the base film corresponding to the region where the spacer does not exist. The optical modulator of claim 11, wherein a height difference between the most convex region and the most concave region in the surface curvature is 0.1 μm to 1 μm. The optical modulator of claim 1, wherein at least one of the first base film and the second base film is a flexible film. The optical modulator of claim 1, further comprising a first electrode layer inside the first base film, and further including a second electrode layer inside the second base film. The light modulator of claim 1, wherein transmittance is varied depending on whether voltage is applied to the light modulator layer. The light modulator of claim 1, wherein the light modulator layer comprises a liquid crystal compound as a light modulator. The method of claim 1, further comprising a functional layer disposed outside the buffer layer, wherein the functional layer includes an anti-fog layer, a self-healing layer, and an anti-reflection layer. Light modulation device including reflection layer, anti-finger layer, anti-fouling layer, anti-glare layer, mirror layer or hardness enhancement layer . A flexible display device comprising the light modulator of claim 1. The device of claim 19, wherein the flexible display device is eyewear. The eyewear includes a left eye lens and a right eye lens, each including the optical modulation device of claim 1; And a frame supporting the left eye lens and the right eye lens.

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