JP2023004661A - Dimming sheet - Google Patents

Abstract

To provide a dimming sheet capable of increasing opaqueness when being energized.SOLUTION: A dimming layer 13 includes a first area being in contact with a first vertical orientation film 11 and a second area being in contact with a second vertical orientation film 12. The first area and the second area include liquid crystal molecules 13LM. As viewed from a visual point opposing a plane in which the dimming layer 13 is extended, in a state where voltage is applied to the dimming layer 13, the first vertical orientation film 11 has orientation regulating force that horizontally orients the liquid crystal molecules 13LM included in the first area in a first direction. The liquid crystal molecules 13LM included in the second area include the liquid crystal molecules 13LM that are horizontally oriented in directions other than the first direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to a reverse type light control sheet.

A reverse type light control sheet includes a light control layer containing liquid crystal molecules, and a pair of alignment films that are in contact with the light control layer and sandwich the light control layer. Each alignment film is, for example, a vertical alignment film, and aligns the liquid crystal molecules so that the long axis of each liquid crystal molecule is substantially perpendicular to the alignment film in a state where no potential difference is generated between the pair of transparent electrode layers. Therefore, the reverse type light control sheet is transparent when no potential difference is generated between the pair of transparent electrode layers. On the other hand, when a potential difference is generated between the pair of transparent electrode layers, the liquid crystal molecules are oriented along the direction perpendicular to the direction of the electric field, thereby making the light control sheet opaque (see, for example, Patent Document 1). ).

JP 2019-194654 A

A reverse type light control sheet having such a structure is required to have higher opacity when a potential difference is generated between a pair of transparent electrode layers.

A light control sheet for solving the above problems comprises a first vertical alignment film, a second vertical alignment film, and a light control layer positioned between the first vertical alignment film and the second vertical alignment film. a transparent resin layer having a plurality of domains; and a light control layer including a plurality of liquid crystal molecules positioned within the domains. The light control layer includes a first region in contact with the first vertical alignment film and a second region in contact with the second vertical alignment film, and the first region and the second region contain the liquid crystal molecules. . When viewed from a viewpoint facing the plane on which the light control layer extends, the first vertical alignment film aligns the liquid crystal molecules contained in the first region in the first direction when a voltage is applied to the light control layer. It has an orientation regulating force for horizontal orientation. The liquid crystal molecules included in the second region include liquid crystal molecules horizontally aligned in a direction other than the first direction.

According to the light control sheet, the liquid crystal molecules contained in the first region are horizontally aligned along the first direction when a voltage is applied to the light control layer. Therefore, compared to the case where the long axes of the liquid crystal molecules included in the first region are randomly aligned, the first region is viewed from the light incident on the first region, and the liquid crystal molecules A large difference in refractive index from the resin layer is maintained over the entire plane on which the light modulating layer extends. This makes it easier for light to scatter in the first region, so that the opacity of the light control layer and thus of the light control sheet including the light control layer is increased when a voltage is applied to the light control layer.

In the light control sheet, the second vertical alignment film is included in the second region when a voltage is applied to the light control layer when viewed from a viewpoint facing the plane on which the light control layer extends. The liquid crystal molecules may be horizontally aligned in a second direction, and the second direction may be a direction crossing the first direction.

The difference in refractive index between the liquid crystal molecules aligned in the first direction and the resin layer is not sufficiently high when viewed from part of the light incident on the first region. Not sufficiently scattered. In this respect, according to the light control sheet, the liquid crystal molecules contained in the second region are aligned along the second direction that intersects with the first direction. The components that were not sufficiently scattered in the are scattered in the second region. As a result, the opacity of the light control layer, and thus of the light control sheet including the light control layer, is enhanced when a voltage is applied to the light control layer.

In the light control sheet, the second direction may be a direction orthogonal to the first direction when viewed from a viewpoint facing the plane on which the light control layer extends. The liquid crystal molecules have an extraordinary refractive index _ne in the major axis direction and an ordinary refractive _index no in the direction perpendicular to the major axis. Therefore, the components that are not scattered in the first region are most likely to scatter in the second direction, which is the direction orthogonal to the first direction, due to the increased refractive index. In this regard, it is preferable that the second direction is a direction orthogonal to the first direction, as in the light control sheet.

In the light control sheet, the light control layer includes the first region, the second region, and a central region located between the first region and the second region, and the plurality of domains are composed of a plurality of and a plurality of second domains, wherein the first region includes a plurality of first domains, a portion of the liquid crystal molecules is located in each first domain, and the second region may include a plurality of second domains, each second domain having a portion of the liquid crystal molecules located therein, and the central region being free of the domains.

According to the above-described light control sheet, liquid crystal molecules are not located in the central region, so light scattering is less likely to occur in the central region. tends to be low. Therefore, in the light control sheet, the effectiveness of the first vertical alignment film to orient the liquid crystal molecules in the first domain along the first direction is enhanced.

In the light control sheet, each first domain may be in contact with the first vertical alignment film, and each second domain may be in contact with the second vertical alignment film. According to this light control sheet, the distance between the liquid crystal molecules contained in the first region and the first vertical alignment film and the distance between the liquid crystal molecules contained in the second region and the second vertical alignment film are , becomes even smaller. Therefore, when the dimming layer is energized, the ratio of the liquid crystal molecules oriented according to the alignment control force of the first vertical alignment film among the liquid crystal molecules contained in the first region is further increased, and the second vertical alignment film is oriented. The proportion of liquid crystal molecules aligned according to the alignment control force is further increased. This makes it possible to increase the opacity when a voltage is applied to the light modulating layer.

ADVANTAGE OF THE INVENTION According to this invention, the opacity at the time of electricity supply can be improved.

It is a sectional view showing structure of a light control device provided with a light control sheet of a 1st embodiment. 1. It is sectional drawing which shows typically the structure at the time of non-energization in the light control layer with which the light control sheet shown in FIG. 1 is provided. FIG. 3 is a perspective view for explaining alignment directions of liquid crystal molecules in the light control sheet shown in FIG. 2 ; 1. It is sectional drawing which shows typically the structure at the time of electricity supply in the light control layer with which the light control sheet shown in FIG. 1 is provided. FIG. 5 is a perspective view for explaining the alignment direction of liquid crystal molecules in the light control sheet shown in FIG. 4; FIG. 10 is a perspective view for explaining the orientation direction of liquid crystal molecules in the light control layer included in the light control sheet of the second embodiment when no current is supplied. FIG. 4 is a cross-sectional view schematically showing the structure of the light control layer included in the light control sheet of the same embodiment when current is applied. FIG. 8 is a perspective view for explaining the alignment direction of liquid crystal molecules in the light control sheet shown in FIG. 7;

[First embodiment]
A first embodiment of the light control sheet will be described with reference to FIGS. 1 to 5. FIG.
[structure]
The structure of the light control sheet will be described with reference to FIGS. 1 to 3. FIG. Note that the light control sheet is attached to, for example, windows of moving bodies such as vehicles and airplanes. In addition, the light control sheet is attached to, for example, windows of various buildings such as houses, stations, and airports, partitions installed in offices, show windows installed in stores, and screens for projecting images. The shape of the light control sheet may be planar or curved.

FIG. 1 shows the structure of a light control device provided with a light control sheet.
As shown in FIG. 1 , the light control sheet 10 includes a first vertical alignment film 11 , a second vertical alignment film 12 and a light control layer 13 . The dimming layer 13 is positioned between the first vertical alignment film 11 and the second vertical alignment film 12 . The light control layer 13 is in contact with the first vertical alignment film 11 and the second vertical alignment film 12 . The light control layer 13 contains a plurality of liquid crystal molecules.

The light control sheet 10 further includes a first transparent electrode layer 14 and a second transparent electrode layer 15 . The first vertical alignment film 11 is located between the first transparent electrode layer 14 and the light control layer 13 . The second vertical alignment film 12 is positioned between the second transparent electrode layer 15 and the light control layer 13 . The light control sheet 10 further includes a first transparent base material 16 and a second transparent base material 17 . The first transparent substrate 16 supports the first transparent electrode layer 14 . A second transparent substrate 17 supports the second transparent electrode layer 15 .

Materials forming the transparent substrates 16 and 17 may be synthetic resins or inorganic compounds. Synthetic resins are, for example, polyesters, polyacrylates, polycarbonates and polyolefins. Polyesters are, for example, polyethylene terephthalate and polyethylene naphthalate. Polyacrylate is, for example, polymethyl methacrylate. Inorganic compounds include, for example, silicon dioxide, silicon oxynitride, and silicon nitride. The thickness of each of the transparent substrates 16 and 17 may be, for example, 16 μm or more and 250 μm or less. Since the transparent base materials 16 and 17 have a thickness of 16 μm or more, the light control sheet 10 can be easily processed and applied. Since the thickness of the transparent substrates 16 and 17 is 250 μm or less, it is possible to manufacture the light control sheet 10 by roll-to-roll.

The light control device 20 includes the light control sheet 10, the first electrode 14A, the second electrode 15A, the driving section 21, and the wiring 22 described above. The first electrode 14A is attached to part of the first transparent electrode layer 14 . A second electrode 15A is attached to a portion of the second transparent electrode layer 15 . The drive unit 21 is connected to the first electrode 14A and the second electrode 15A by wiring 22 .

Each electrode 14A, 15A is, for example, a flexible printed circuit board (FPC: Flexible Printed Circuits). The FPC has a support layer, a conductor portion, and a protective layer. A conductor portion is sandwiched between the support layer and the protective layer. The support layer and the protective layer are made of insulating synthetic resin. The support layer and the protective layer are made of polyimide, for example. The conductor portion is formed of, for example, a metal thin film. The material forming the metal thin film may be copper, for example. Each electrode 14A, 15A is not limited to FPC, and may be, for example, a metal tape.

Each electrode 14A, 15A is attached to each transparent electrode layer 14, 15 by a conductive adhesive layer (not shown). In the portions of the electrodes 14A and 15A that are connected to the conductive adhesive layer, the conductor portions are exposed from the protective layer or support layer.

The conductive adhesive layer is, for example, an anisotropic conductive film (ACF: Anisotropic Conductive Film), an anisotropic conductive paste (ACP: Anisotropic Conductive Paste), an isotropic conductive film (ICF: Isotropic Conductive Film), and the like. It may be formed by directional conductive paste (ICP: Isotropic Conductive Paste) or the like. From the viewpoint of handleability in the manufacturing process of the light control device 20, the conductive adhesive layer is preferably an anisotropic conductive film.

The wiring 22 is formed of, for example, a metal wire and an insulating layer covering the metal wire. The wire is made of, for example, copper.
The drive unit 21 applies an AC voltage between the first transparent electrode layer 14 and the second transparent electrode layer 15 . It is preferable that the drive unit 21 applies an AC voltage having a rectangular waveform between the pair of transparent electrode layers 14 and 15 . In addition, the drive unit 21 may apply an AC voltage having a shape other than a rectangular wave between the pair of transparent electrode layers 14 and 15 . For example, the drive unit 21 may apply a sinusoidal AC voltage between the pair of transparent electrode layers 14 and 15 .

The light control layer 13 is subjected to a change in voltage occurring between the two transparent electrode layers 14, 15, thereby changing the orientation of the liquid crystal molecules. A change in the orientation of the liquid crystal molecules changes the degree of scattering, absorption, and transmission of visible light entering the light control layer 13 . The reverse type light control sheet 10 exhibits a relatively high haze when the light control sheet 10 is energized, that is, when a potential difference is generated between the first transparent electrode layer 14 and the second transparent electrode layer 15 . have. The reverse type light control sheet 10 has a relatively low haze when the light control sheet 10 is not energized, that is, when no potential difference is generated between the first transparent electrode layer 14 and the second transparent electrode layer 15. have

FIG. 2 schematically shows the cross-sectional structure of the light control sheet 10 along the thickness direction of the light control layer 13 . Note that in FIG. 2, for the convenience of describing the structure of the light control layer 13 in detail, the light control layer 13 is significantly larger than the vertical alignment films 11 and 12, the transparent electrode layers 14 and 15, and the transparent substrates 16 and 17. thickly illustrated. 2 schematically shows the cross-sectional structure of the light control sheet 10 when no voltage is applied to the light control layer 13. As shown in FIG.

As shown in FIG. 2, the light control layer 13 includes a transparent resin layer 13P and a liquid crystal composition 13L. The liquid crystal composition 13L fills the domains of the resin layer 13P. The liquid crystal composition 13L contains a plurality of liquid crystal molecules 13LM. Examples of liquid crystal molecules 13LM include Schiff base, azo, azoxy, biphenyl, terphenyl, benzoate, tolan, pyrimidine, cyclohexanecarboxylate, phenylcyclohexane, and dioxane systems. is any selected from the group consisting of: The liquid crystal molecules 13LM are negative liquid crystals with negative dielectric anisotropy.

Note that the liquid crystal composition 13L may include a polymerizable composition for forming the resin layer 13P, a dichroic dye, and the like, in addition to the liquid crystal molecules 13LM described above. A polymerizable composition is a monomer or oligomer that can be polymerized by irradiation with ultraviolet light.

The resin layer 13P is a polymer of a polymerizable composition. As mentioned above, the polymerizable composition is a monomer or polymer that can be polymerized by irradiation with ultraviolet light.
The light modulating layer 13 is composed of a first region, a second region, and a central region. The first region is in contact with the first vertical alignment film 11 . The second region is in contact with the second vertical alignment film 12 . The central region is located between the first region and the second region in the thickness direction of the light modulating layer 13 . Each region has a layered shape that extends over the entire light control layer 13 when viewed from a viewpoint facing the plane on which the light control layer 13 extends. The central region includes a portion located in the center of the light modulating layer 13 in the thickness direction.

The first region includes a plurality of first domains 13D1. A part of the liquid crystal molecules 13LM in the light control layer 13 is located in each first domain 13D1. The second region includes a plurality of second domains 13D2. A part of the liquid crystal molecules 13LM in the light control layer 13 is located in each second domain 13D2. The central region does not contain domains.

Each domain 13D1, 13D2 is a void formed in the resin layer 13P. Each domain 13D1, 13D2 is filled with a liquid crystal composition 13L, whereby a part of the liquid crystal molecules 13LM in the light control layer 13 is located in each domain 13D1, 13D2. Therefore, in the light modulating layer 13, the density of the first domains 13D1 in the first region and the density of the second domains 13D2 in the second region are higher than the density of the domains in the central region. In other words, in the light modulating layer 13, the density of the liquid crystal molecules 13LM in the first region and the density of the liquid crystal molecules 13LM in the second region are higher than the density of the liquid crystal molecules 13LM in the central region. The density of domains in each region may be, for example, the ratio of the sum of the areas of domains to the total area of each region.

In this embodiment, the first region has a thickness capable of including the entirety of all first domains 13D1. Also, the second region has a thickness capable of including the entirety of all the second domains 13D2. The thickness of the first region is equal to the maximum distance between the first vertical alignment film 11 and the first domain 13D1. Also, the thickness of the second region is equal to the maximum distance between the second vertical alignment film 12 and the second domain 13D2.

Each first domain 13D1 is in contact with the first vertical alignment film 11. As shown in FIG. Also, each second domain 13D2 is in contact with the second vertical alignment film 12 . In a cross section along the thickness direction of the light modulating layer 13, each of the domains 13D1 and 13D2 has a substantially arc shape. Each of the domains 13D1 and 13D2 may have a semicircular shape, a circular shape larger than a semicircular shape, or a circular shape smaller than a semicircular shape. From the viewpoint of shortening the distance between each of the vertical alignment films 11 and 12 and the liquid crystal molecules 13LM, each of the domains 13D1 and 13D2 preferably has a size equal to or smaller than a semicircle.

In a cross section along the thickness direction of the light modulating layer 13, the maximum distance between the first vertical alignment film 11 and the first domain 13D1 may be, for example, 4 μm or less. Similarly, the maximum distance between the second vertical alignment film 12 and the second domain 13D2 may be, for example, 4 μm or less.

The thickness of the light modulating layer 13 may be, for example, 2 μm or more and 11 μm or less. The thickness of the light modulating layer 13 of 2 μm or more is preferable in that at least two regions having mutually different densities of the liquid crystal molecules 13LM can be generated in the light modulating layer 13 . Further, since the thickness of the light control layer 13 is 11 μm or less, the liquid crystal molecules 13LM and the resin layer 13P are appropriately separated when the coating liquid containing the liquid crystal molecules is exposed during the manufacturing of the light control sheet 10. be. Note that the maximum value of the distance between the first vertical alignment film 11 and the first domain 13D1 and the maximum value of the distance between the second vertical alignment film 12 and the second domain 13D2 are It is less than 1/2 in thickness of 13.

The first transparent electrode layer 14 and the second transparent electrode layer 15 have optical transparency to transmit visible light. The light transmittance of the first transparent electrode layer 14 enables visual recognition of objects through the light control sheet 10 . The light transmittance of the second transparent electrode layer 15, like the light transmittance of the first transparent electrode layer 14, enables visual recognition of an object through the light control sheet 10. FIG. The thickness of each of the transparent electrode layers 14 and 15 may be, for example, 0.005 μm or more and 0.1 μm or less. This makes it possible to reduce cracks that may occur when the light control sheet 10 is bent while ensuring proper driving of the light control sheet 10 .

Materials for forming the transparent electrode layers 14 and 15 include, for example, indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, poly(3,4-ethylenedioxythiophene), and silver. Any one selected from the group consisting of

Materials for forming the first vertical alignment film 11 and the second vertical alignment film 12 are organic compounds, inorganic compounds, and mixtures thereof. Organic compounds include, for example, polyimides, polyamides, polyvinyl alcohols, and cyanide compounds. Inorganic compounds include silicon oxide and zirconium oxide. The material for forming the vertical alignment films 11 and 12 may be silicone. Silicones are compounds that have an inorganic portion and an organic portion. The thickness of each of the vertical alignment films 11 and 12 is, for example, 0.02 μm or more and 0.5 μm or less.

FIG. 3 schematically shows the alignment regulating force of the first vertical alignment film 11 together with the liquid crystal molecules 13LM. FIG. 3 shows the state of the liquid crystal molecules 13LM when no voltage is applied to the light modulating layer 13. As shown in FIG.

As shown in FIG. 3, the first vertical alignment film 11 has a surface 11F. The surface 11</b>F is the surface of the first vertical alignment film 11 opposite to the surface in contact with the first transparent electrode layer 14 . The first vertical alignment film 11 orients the liquid crystal molecules 13LM such that the long axes of the liquid crystal molecules 13LM are perpendicular to the surface 11F when the light control layer 13 is not energized.

The second vertical alignment film 12 has a surface 12F. The surface 12</b>F is the surface opposite to the surface in contact with the second transparent electrode layer 15 . The second vertical alignment film 12 orients the liquid crystal molecules 13LM such that the long axes of the liquid crystal molecules 13LM are perpendicular to the surface 12F when the light control layer 13 is not energized. The angles formed by the respective vertical alignment films 11 and 12 and the long axes of the liquid crystal molecules 13LM may deviate from the right angle within the range where they can be regarded as substantially right angles.

When a voltage is applied to the light control layer 13, the first vertical alignment film 11 aligns the liquid crystal molecules 13LM included in the first region in the first direction D1 when viewed from a viewpoint facing the plane where the light control layer 13 extends. It has an orientation regulating force for horizontal orientation. A voltage is applied to the light control layer 13 by applying a voltage between the first transparent electrode layer 14 and the second transparent electrode layer 15 .

The liquid crystal molecules 13LM contained in the light control layer 13 are aligned along the direction perpendicular to the electric field formed in the light control layer 13 . As a result, the liquid crystal molecules 13LM are aligned along the surface 11F of the first vertical alignment film 11 . At this time, the first vertical alignment film 11 horizontally aligns the liquid crystal molecules 13LM included in the first region in the first direction D1. Therefore, the liquid crystal molecules 13LM included in the first region are aligned along a plane parallel to the surface 11F of the first vertical alignment film 11 with the long axis along the first direction D1.

A surface 11F of the first vertical alignment film 11 is subjected to a rubbing treatment. As a result, the surface 11F of the first vertical alignment film 11 is provided with an alignment regulating force such that the long axes of the horizontally aligned liquid crystal molecules 13LM are aligned along the first direction D1.

On the other hand, the surface 12F of the second vertical alignment film 12 is not provided with an alignment regulating force that causes the long axes of the liquid crystal molecules 13LM to follow a specific direction. Therefore, in a state in which a voltage is applied to the light control layer 13, the liquid crystal molecules 13LM included in the second region are aligned along a plane parallel to the second vertical alignment film 12, while the long axes of the liquid crystal molecules 13LM are randomly oriented. In other words, the liquid crystal molecules 13LM included in the second region include liquid crystal molecules horizontally aligned in directions other than the first direction D1.

[Action]
The operation of the light control sheet 10 will be described with reference to FIGS. 2 to 5. FIG. 2 and 3 schematically show a state in which no voltage is applied to the light-modulating layer 13, as described above, while FIGS. It schematically shows the state of

As shown in FIG. 2, when no voltage is applied to the light modulating layer 13, the vertical alignment films 11 and 12 vertically align the liquid crystal molecules 13LM located near the vertical alignment films 11 and 12. As shown in FIG.

That is, as shown in FIG. 3, the first vertical alignment film 11 aligns the liquid crystal molecules 13LM positioned within the first domain 13D1 such that the long axes of the liquid crystal molecules 13LM are perpendicular to the surface 11F. In addition, the second vertical alignment film 12 orients the liquid crystal molecules 13LM positioned in the second domain 13D2 such that the long axes of the liquid crystal molecules 13LM are perpendicular to the surface 12F.

As a result, the resin layer 13</b>P included in the light control layer 13 can be seen from the light that has entered the light control layer 13 through the first vertical alignment film 11 and the light that has entered the light control layer 13 through the second vertical alignment film 12 . Almost no difference occurs between the refractive index and the refractive index of the liquid crystal molecules 13LM. As a result, both the light that has entered the light control layer 13 through the first vertical alignment film 11 and the light that has entered the light control layer 13 through the second vertical alignment film 12 are less likely to be scattered in the light control layer 13. , go straight through the light modulating layer 13 . Thereby, the light control sheet 10 including the light control layer 13 exhibits transparency.

On the other hand, as shown in FIG. 4, when a voltage is applied to the light control layer 13, the liquid crystal molecules 13LM located in the respective domains 13D1 and 13D2 have their long axes aligned with the electric field direction. The liquid crystal molecules 13LM are oriented so that they are vertical.

As shown in FIG. 5 and as described above, the surface 11F of the first vertical alignment film 11 is provided with an alignment regulating force to align the long axes of the liquid crystal molecules 13LM along the first direction D1. . Therefore, the liquid crystal molecules 13LM located in the vicinity of the first vertical alignment film 11, that is, in the first domain 13D1, are horizontally aligned such that their long axes are along the first direction D1. On the other hand, the liquid crystal molecules 13LM located in the vicinity of the second vertical alignment film 12, that is, in the second domain 13D2, are horizontally aligned so that their long axes are oriented in random directions.

Here, in the liquid crystal molecules 13LM, the refractive index in the major axis direction differs from the refractive index in the direction perpendicular to the major axis. The refractive index in the long axis direction is the extraordinary ray refractive index _ne , and the refractive index in the direction perpendicular to the long axis is the ordinary ray refractive _index no. The refractive index n _e of extraordinary light is greater than the refractive index n _o of ordinary light. Therefore, when the liquid crystal molecules 13LM are horizontally aligned, the difference between the refractive index of the liquid crystal molecules 13LM and the resin layer 13P is greater than when the liquid crystal molecules 13LM are vertically aligned, thereby adjusting the light. Light incident on the layer 13 is scattered in the light control layer 13 . As a result, the light control layer 13 and the light control sheet 10 including the light control layer 13 become cloudy.

When the liquid crystal molecules 13LM are horizontally aligned and the long axes of the liquid crystal molecules 13LM are randomly aligned, the refractive index of the liquid crystal molecules 13LM is the same as the length of the liquid crystal molecules 13LM when viewed from the light incident on the light control layer 13. Varies depending on the direction the axis points. Therefore, when the directions of the long axes of the liquid crystal molecules 13LM are random, the directions of the long axes of the liquid crystal molecules 13LM are such that the difference in refractive index between the liquid crystal molecules 13LM and the resin layer 13P is reduced. Includes orientation.

In this regard, in the light control layer 13 of the present embodiment, the first vertical alignment film 11 aligns the liquid crystal molecules 13LM in the first domain 13D1 in the first direction D1. Therefore, with respect to part of the light incident on the first region, the first region assumes a state in which the difference in refractive index between the liquid crystal molecules 13LM and the resin layer 13P is large. maintained in As a result, light scattering is likely to occur in the first region, so that the opacity of the light control layer 13 and the light control sheet 10 including the light control layer 13 is reduced when a voltage is applied to the light control layer 13. Increased.

In addition, in the light control layer 13, the liquid crystal molecules 13LM are located in the first region and the second region, but the liquid crystal molecules 13LM are not located in the central region. Therefore, scattering of light is less likely to occur in the central region, and as a result, the opacity of the light-modulating layer 13 tends to be low when a voltage is applied to the light-modulating layer 13 . That is, the haze of the light-modulating layer 13 is likely to decrease in a state where voltage is applied to the light-modulating layer 13 . Therefore, in the light control layer 13 of the present embodiment, the effectiveness of the first vertical alignment film 11 to orient the liquid crystal molecules 13LM in the first domain 13D1 along the first direction D1 is enhanced.

Also, the first domain 13D1 is in contact with the first vertical alignment film 11, and the second domain 13D2 is in contact with the second vertical alignment film 12. As shown in FIG. As a result, the distance between the liquid crystal molecules 13LM included in the first region and the first vertical alignment film 11 and the distance between the liquid crystal molecules 13LM included in the second region and the second vertical alignment film 12 are become even smaller. Therefore, when the dimming layer 13 is energized, the ratio of the liquid crystal molecules 13LM aligned according to the alignment control force of the first vertical alignment film 11 among the liquid crystal molecules 13LM contained in the first region is further increased. Moreover, the ratio of the liquid crystal molecules 13LM aligned according to the alignment control force of the second vertical alignment film 12 is further increased. This makes it possible to increase the opacity when a voltage is applied to the light modulating layer 13 .

Thus, the light control sheet 10 with enhanced opacity when energized can withstand use in an environment where privacy protection is more required. In addition, the contrast between transparency when not energized and opacity when energized is enhanced, thereby enhancing the design of the environment to which the light control sheet 10 is applied.

As in this embodiment, in the reverse type light control sheet 10 using the pair of vertical alignment films 11 and 12 and the negative type liquid crystal molecules 13LM, the resin layer 13P is vertically aligned in the portions other than the domains 13D1 and 13D2. It is in contact with the alignment films 11 and 12 . Therefore, the adhesion between the light modulating layer 13 and the vertical alignment films 11 and 12 is enhanced. Therefore, the light control sheet 10 also has a structure suitable for production using the roll-to-roll method.

As described above, according to the first embodiment of the light control sheet, the effects described below can be obtained.
(1-1) The first region adjusts a state in which the difference in refractive index between the liquid crystal molecules 13LM and the resin layer 13P is large with respect to a part of the light incident on the first region. It is maintained throughout the plane in which the optic layer 13 extends. As a result, light scattering is likely to occur in the first region, so that the opacity of the light control layer 13 and the light control sheet 10 including the light control layer 13 is reduced when a voltage is applied to the light control layer 13. Increased.

(1-2) Since the liquid crystal molecules 13LM are not located in the central region, scattering of light is less likely to occur in the central region. tends to be low. Therefore, in the light control sheet 10, the effectiveness of the first vertical alignment film 11 to orient the liquid crystal molecules 13LM in the first domains 13D1 along the first direction D1 is enhanced.

(1-3) When the light control layer 13 is energized, the ratio of the liquid crystal molecules 13LM aligned according to the alignment control force of the first vertical alignment film 11 among the liquid crystal molecules 13LM contained in the first region is further increased. Moreover, the ratio of the liquid crystal molecules 13LM aligned according to the alignment control force of the second vertical alignment film 12 is further increased. This makes it possible to increase the opacity when a voltage is applied to the light modulating layer 13 .

[Second embodiment]
2nd Embodiment of a light control sheet is described with reference to FIGS. 6-8. In the second embodiment of the light control sheet, the second alignment film included in the light control sheet is different from the second alignment film included in the light control sheet of the first embodiment. Therefore, hereinafter, while such differences will be described in detail, the same reference numerals as in the first embodiment are assigned to the same configurations in the light control sheet of the second embodiment as those of the light control sheet of the first embodiment. Further, detailed description of the configuration is omitted.

[structure]
The structure of the light control sheet will be described with reference to FIG. FIG. 6 schematically shows the alignment regulating force possessed by the first vertical alignment film and the second vertical alignment film together with the liquid crystal molecules 13LM. FIG. 6 shows the state of the liquid crystal molecules 13LM when no voltage is applied to the light control layer 13. As shown in FIG.

As shown in FIG. 6, the second vertical alignment film 32 has a surface 32F. The surface 32</b>F is the surface opposite to the surface in contact with the second transparent electrode layer 15 . As with the second vertical alignment film 12 of the first embodiment, the second vertical alignment film 32 is arranged so that the major axes of the liquid crystal molecules 13LM are perpendicular to the surface 32F when the light control layer 13 is not energized. , the liquid crystal molecules 13LM are aligned.

The second vertical alignment film 32 aligns the liquid crystal molecules 13LM included in the second region in the second direction D2 when viewed from a viewpoint facing the plane where the light control layer 13 extends in a state where a voltage is applied to the light control layer 13 . It has an orientation regulating force for horizontal orientation. The second direction D2 is a direction crossing the first direction D1. In the present embodiment, the second direction D2 is a direction orthogonal to the first direction D1 when viewed from a viewpoint facing the plane on which the light modulating layer 13 extends.

The liquid crystal molecules 13LM contained in the light control layer 13 are aligned along the direction perpendicular to the electric field formed in the light control layer 13 . As a result, the liquid crystal molecules 13LM are aligned along the surface 32F of the second vertical alignment film 32. FIG. At this time, the second vertical alignment film 32 horizontally aligns the liquid crystal molecules 13LM included in the second region in the second direction D2. Therefore, the liquid crystal molecules 13LM included in the second region are aligned along a plane parallel to the surface 32F of the second vertical alignment film 32 with the long axis along the second direction D2.

A surface 32F of the second vertical alignment film 32 is subjected to a rubbing treatment. As a result, the surface 32F of the second vertical alignment film 32 is provided with an alignment regulating force that aligns the long axes of the horizontally aligned liquid crystal molecules 13LM along the second direction D2.

On the other hand, as described in the first embodiment, the surface 11F of the first vertical alignment film 11 is provided with an alignment regulating force that aligns the long axes of the horizontally aligned liquid crystal molecules 13LM along the first direction D1. ing. Therefore, when a voltage is applied to the light control layer 13, when viewed from a viewpoint facing the surface 11F of the first vertical alignment film 11, the long axis of the liquid crystal molecules 13LM included in the first region and the second The long axes of the liquid crystal molecules 13LM included in the two regions are orthogonal to each other.

[Action]
The operation of the light control sheet 10 will be described with reference to FIGS. 6 to 8. FIG. 6 schematically shows a state in which no voltage is applied to the light-modulating layer 13 as described above, while FIGS. 7 and 8 show states in which a voltage is applied to the light-modulating layer 13. is schematically shown. The light control sheet 10 of the second embodiment has a state equivalent to that of the light control sheet 10 of the first embodiment when no voltage is applied to the light control layer 13 . Therefore, in the second embodiment, illustration of the light control sheet 10 in a state where no voltage is applied to the light control layer 13 is omitted.

As shown in FIG. 6, the first vertical alignment film 11 aligns the liquid crystal molecules 13LM positioned within the first domain 13D1 such that the long axes of the liquid crystal molecules 13LM are perpendicular to the surface 11F. In addition, the second vertical alignment film 32 orients the liquid crystal molecules 13LM positioned in the second domain 13D2 so that the long axes of the liquid crystal molecules 13LM are perpendicular to the surface 32F.

As a result, the resin layer 13</b>P included in the light control layer 13 can be seen from the light that has entered the light control layer 13 through the first vertical alignment film 11 and the light that has entered the light control layer 13 through the second vertical alignment film 32 . Almost no difference occurs between the refractive index and the refractive index of the liquid crystal molecules 13LM. As a result, both the light that has entered the light control layer 13 through the first vertical alignment film 11 and the light that has entered the light control layer 13 through the second vertical alignment film 12 are less likely to be scattered in the light control layer 13. , go straight through the light modulating layer 13 . Thereby, the light control sheet 10 including the light control layer 13 exhibits transparency.

On the other hand, as shown in FIG. 7, when a voltage is applied to the light control layer 13, the liquid crystal molecules 13LM located in the respective domains 13D1 and 13D2 have their major axes aligned with the electric field direction. The liquid crystal molecules 13LM are oriented so that they are vertical.

As shown in FIG. 8 and as described above, the surface 11F of the first vertical alignment film 11 is provided with an alignment regulating force to align the long axes of the liquid crystal molecules 13LM along the first direction D1. . Therefore, the liquid crystal molecules 13LM located in the vicinity of the first vertical alignment film 11, that is, in the first domain 13D1, are horizontally aligned such that their long axes are along the first direction D1.

On the other hand, the surface 32F of the second vertical alignment film 32 is provided with an alignment regulating force that aligns the long axes of the liquid crystal molecules 13LM along the second direction D2. Therefore, the liquid crystal molecules 13LM positioned in the vicinity of the second vertical alignment film 32, that is, in the second domain 13D2, are horizontally aligned such that the major axes thereof are along the second direction D2.

As described above, the first vertical alignment film 11 aligns the liquid crystal molecules 13LM in the first domain 13D1 in the first direction D1. Therefore, with respect to part of the light incident on the first region, the first region assumes a state in which the difference in refractive index between the liquid crystal molecules 13LM and the resin layer 13P is large. maintained in As a result, light scattering is likely to occur in the first region, so that the opacity of the light control layer 13 and the light control sheet 10 including the light control layer 13 is reduced when a voltage is applied to the light control layer 13. Increased.

On the other hand, the difference in refractive index between the liquid crystal molecules 13LM aligned in the first direction D1 and the resin layer 13P is not sufficiently high when viewed from part of the light incident on the first region. , is not sufficiently scattered in the first region. In this regard, since the liquid crystal molecules 13LM included in the second region are aligned along the second direction D2 orthogonal to the first direction D1, the light incident on the light control layer 13 is sufficiently scattered in the first region. The components that are not scattered are scattered in the second region. As a result, the opacity of the light control layer 13 and thus the light control sheet 10 including the light control layer 13 is increased when a voltage is applied to the light control layer 13 .

Note that the first direction D1 and the second direction D2 are not limited to being perpendicular to each other when viewed from a viewpoint facing the plane on which the light control layer 13 extends, and the angle formed by the first direction D1 and the second direction D2 is The opacity of the light control sheet 10 is similarly enhanced when the angle is other than 90 degrees. In this regard, as described above, the liquid crystal molecules _13LM have an extraordinary ray refractive index ne in the long axis direction and an ordinary _ray refractive index no in the direction perpendicular to the long axis. Therefore, the components that are not scattered in the first region are most likely to scatter due to the increased refractive index in the second direction D2, which is the direction orthogonal to the first direction D1. Therefore, the second direction D2 is preferably a direction perpendicular to the first direction D1.

As described above, according to the second embodiment of the light control sheet, the effects described below can be obtained.
(2-1) Since the liquid crystal molecules 13LM included in the second region are aligned along the second direction D2 that intersects with the first direction D1, the light incident on the light control layer 13 is sufficient in the first region. The components not scattered to are scattered in the second region. As a result, the opacity of the light control layer 13 and thus the light control sheet 10 including the light control layer 13 is increased when a voltage is applied to the light control layer 13 .

(2-2) Since the second direction D2 is a direction orthogonal to the first direction D1, the component not scattered in the first region is refracted in the second direction D2, which is a direction orthogonal to the first direction D1. The higher the index, the more likely it is to scatter.

[Change example]
In addition, each embodiment mentioned above can be changed as follows and can be implemented.
[Light control layer]
- At least part of the first domain 13D1 does not have to be in contact with the first vertical alignment film 11 . Even in this case, the first vertical alignment film 11 aligns the liquid crystal molecules 13LM in the first direction D1 in a state in which a voltage is applied to the light control layer 13, so that the above-described (1-1) You can get the same effect.

- At least part of the second domain 13D2 does not have to be in contact with the second vertical alignment film 12 . Even in this case, the first vertical alignment film 11 aligns the liquid crystal molecules 13LM in the first direction D1 in a state in which a voltage is applied to the light control layer 13, so that the above-described (1-1) You can get the same effect.

- A domain may be located in the central region of the light modulating layer 13 . In this case, the density of the first domains 13D1 in the first region and the density of the second domains 13D2 in the second region are preferably higher than the density of the domains in the central region. In other words, the density of the liquid crystal molecules 13LM in the first region and the density of the liquid crystal molecules 13LM in the second region are preferably higher than the density of the liquid crystal molecules 13LM in the central region. Even in this case, the first vertical alignment film 11 aligns the liquid crystal molecules 13LM in the first direction D1 in a state in which a voltage is applied to the light control layer 13, so that the above-described (1-1) You can get the same effect.

DESCRIPTION OF SYMBOLS 10... Light control sheet 11... First vertical alignment film 11F, 12F... Surface 12... Second vertical alignment film 13... Light control layer 13D1... First domain 13D2... Second domain 13LM... Liquid crystal molecule 14... First transparent electrode layer DESCRIPTION OF SYMBOLS 15... 2nd transparent electrode layer 16... 1st transparent base material 17... 2nd transparent base material

Claims (5)

a first vertical alignment film;
a second vertical alignment film;
A light control layer positioned between the first vertical alignment film and the second vertical alignment film, the light control layer including a transparent resin layer having a plurality of domains and a plurality of liquid crystal molecules positioned within the domains. A light control sheet comprising a light layer,
The light control layer includes a first region in contact with the first vertical alignment film and a second region in contact with the second vertical alignment film, and the first region and the second region contain the liquid crystal molecules. ,
Seen from a viewpoint facing the plane on which the light control layer spreads,
The first vertical alignment film has an alignment control force that horizontally aligns the liquid crystal molecules contained in the first region in a first direction when a voltage is applied to the light control layer,
The light control sheet, wherein the liquid crystal molecules contained in the second region include the liquid crystal molecules horizontally aligned in a direction other than the first direction. Seen from a viewpoint facing the plane on which the light control layer spreads,
The second vertical alignment film has an alignment regulating force that horizontally aligns the liquid crystal molecules contained in the second region in a second direction when a voltage is applied to the light control layer. is a direction crossing the first direction. The light control sheet according to claim 2, wherein the second direction is a direction orthogonal to the first direction when viewed from a viewpoint facing the plane on which the light control layer extends. The light control layer is composed of the first region, the second region, and a central region located between the first region and the second region,
The plurality of domains are composed of a plurality of first domains and a plurality of second domains,
the first region includes a plurality of first domains, each of which contains a portion of the liquid crystal molecules;
the second region includes a plurality of second domains, each second domain having a portion of the liquid crystal molecules;
The light control sheet according to any one of claims 1 to 3, wherein the central region does not contain the domain. each first domain is in contact with the first vertical alignment film;
The light control sheet according to claim 4, wherein each second domain is in contact with the second vertical alignment film.

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