Patent Description:
A light control sheet includes a light control layer containing a liquid crystal composition, and a pair of transparent electrode layers sandwiching the light control layer. A drive voltage is applied between the pair of transparent electrode layers. The alignment of liquid crystal molecules of the liquid crystal composition changes according to a potential difference between the transparent electrode layers, leading to a change in light transmittance of the light control sheet. For example, when the major axes of the liquid crystal molecules are aligned in the thickness direction of the light control layer, the light control sheet is colorless and transparent, and has a high light transmittance. When the major axes of the liquid crystal molecules intersect the thickness direction of the light control layer, light is scattered in the light control layer, and the light transmittance of the light control sheet is low (see, for example, Patent Literature <NUM>).

<CIT> discloses a light control sheet having the features of the preamble of claim <NUM>.

<CIT> discloses a transparent display that includes a display screen. The display screen includes a first film that includes a first transparent conductor disposed upon a first transparent substrate and a second film that includes a second transparent conductor disposed upon a second transparent substrate. A first polymeric liquid crystal composition containing spacer beads is disposed between the first film and the second film. At least one of the first transparent conductor and the second transparent conductor is shaped, or at least one of the first transparent conductor and the second transparent conductor is patterned.

<CIT> discloses a liquid crystal layer that is sandwiched between upper and lower substrates wherein a segment electrode (<NUM>) and an auxiliary electrode surrounding the segment electrode with a gap are formed on the upper substrate by using the same transparent conductive film. An opposite electrode is provided over the whole display area of the lower substrate. The overlap between the counter electrode and the segment electrode constitutes a pixel portion, and the overlap between the opposite electrode and the auxiliary electrode constitutes a background portion. Voltages are selectively applied to the liquid crystal layer of the pixel portion and that of the background portion, and thereby the transmission, diffusion, or absorption of the light incident on the liquid crystal layer is arbitrarily varied to conduct display.

<CIT> discloses a liquid crystal display panel that has transparent substrates disposed in order from an observation-surface side to a non-observation-surface side and liquid crystal/cured body complex layers provided among the transparent substrates. Transparent electrodes are formed on the back of the transparent substrate disposed most closely to the observation-surface side, the front of the transparent substrate disposed most closely to the non-observation-surface side, and the front and the back of the transparent substrate sandwiched between the frontmost substrate and rearmost substrate.

<CIT> discloses a lighting control sheet that includes a partition line partitioning a peeling target part in a laminate sheet covering a first transparent electrode layer. The partition line includes: a first recess opened at a second transparent sheet and located closer to the second transparent sheet than the first transparent electrode layer; and a second recess located at a bottom of the first recess. The second recess is aligned in an extension direction of the partition line, and has a width smaller than that of the first recess in a cross section along a depth direction of the lighting control sheet.

<CIT> discloses a liquid crystal display device which includes a thin film transistor including an oxide semiconductor layer, a first electrode layer, a second electrode layer having an opening, a light-transmitting chromatic-color resin layer between the thin film transistor and the second electrode layer, and a liquid crystal layer. One of the first electrode layer and the second electrode layer is a pixel electrode layer which is electrically connected to the thin film transistor, and the other of the first electrode layer and the second electrode layer is a common electrode layer. The light-transmitting chromatic-color resin layer is overlapped with the pixel electrode layer and the oxide semiconductor layer of the thin film transistor.

Light control sheets are adhered to members for partitioning a space, for example, construction materials such as window glasses or partitions of buildings, or window glasses of vehicles, and are used as a part of such members. In recent years, in order to improve the added value of light control sheets, the designability of light control sheets has been attracting attention. Improvement in the designability of light control sheets can significantly increase the applicability of light control sheets, and create a new demand for a space to be light controlled. Thus, it is the object of the present invention to provide a light control sheet having higher designability.

The above object is solved by a light control sheet having the features of claim <NUM>. Further developments are stated in the dependent claims.

A method of producing a light control sheet is stated in claim <NUM>.

The drawings may not be to scale, and the relative sizes, proportions, and depictions of elements in the drawings may be exaggerated for clarity, illustration, and convenience.

An embodiment of a light control sheet and a method of producing the light control sheet will be described with reference to <FIG>. A light control sheet <NUM> of the present embodiment is a normal-type light control sheet in which when no voltage signal is applied to the light control sheet <NUM>, incident light in a region to be driven is scattered to reduce the translucency of the light control sheet <NUM> and when a voltage signal is applied to the light control sheet <NUM>, the translucency of the light control sheet <NUM> is increased.

As shown in <FIG>, the light control sheet <NUM> has a first surface 11F, and a second surface 11R opposite to the first surface 11F. The light control sheet <NUM> has a drive region <NUM> and a non-driven region <NUM>.

The drive region <NUM> is a region in which a driving electrode element <NUM> is located. The driving electrode element <NUM> is an electrode element to which a voltage signal is applied when the light control sheet <NUM> is driven. The light transmittance of the drive region <NUM> changes according to the application state of a voltage signal to the driving electrode element <NUM>. The driving electrode element <NUM> is an example of a first electrode element.

The non-driven region <NUM> includes a floating region <NUM>, and a boundary region <NUM> that surrounds the floating region <NUM>. The floating region <NUM> is a region in which a floating electrode element <NUM> is located. The floating electrode element <NUM> is an electrode element to which no voltage signal is applied when the light control sheet <NUM> is driven. The floating electrode element <NUM> is an example of a second electrode element. The boundary region <NUM> is located between the drive region <NUM> and the floating region <NUM>, and has a closed frame shape surrounding the floating region <NUM>. No electrode element is located in the boundary region <NUM>. The light transmittance of the non-driven region <NUM> does not change in response to the light control sheet <NUM> being driven or not driven.

The non-driven region <NUM> causes the light control sheet <NUM> to display a design. The design is, for example, a character, a number, a symbol, a figure, a pattern, a patterned design, or the like, or a combination thereof. The light control sheet <NUM> shown in <FIG> is configured to display a single star-shaped figure; however, the light control sheet <NUM> may have a plurality of non-driven regions <NUM> separated from each other. That is, the light control sheet <NUM> may have a plurality of boundary regions <NUM> each of which forms a closed region.

A connection region <NUM> is a region for applying a voltage signal to the drive region <NUM>, and external wires <NUM> are connected to the connection region <NUM>. The connection region <NUM> and the drive region <NUM> are adjacent to each other. The position in the light control sheet <NUM> where the connection region <NUM> is to be provided is not particularly limited. The connection region <NUM> is located, for example, in a corner portion of the light control sheet <NUM>.

<FIG> is a cross-sectional view taken along line II-II in <FIG>. That is, <FIG> shows a cross-sectional structure of the light control sheet <NUM> in the drive region <NUM> and the connection region <NUM>. The thickness ratio of the layers in <FIG> is shown for convenience of description, and the thickness ratio of the layers is not limited to the thickness ratio shown in <FIG>.

As shown in <FIG>, the light control sheet <NUM> includes a light control layer <NUM>, a first transparent electrode layer 12A, a second transparent electrode layer 12B, a first transparent support layer 13A, and a second transparent support layer 13B. The light control layer <NUM> is sandwiched between the first transparent electrode layer 12A and the second transparent electrode layer 12B. The first transparent support layer 13A supports the first transparent electrode layer 12A by a support surface <NUM> on the side of the first transparent electrode layer 12A facing away from the light control layer <NUM>. The second transparent support layer 13B supports the second transparent electrode layer 12B on the side of the second transparent electrode layer 12B facing away from the light control layer <NUM>. The light control layer <NUM> may have a single-layer structure or a multilayer structure. The light control layer <NUM> having a multilayer structure may include a functional layer having a light control function, a thin layer for improving adhesion between the functional layer and the first transparent electrode layer 12A, and a thin layer for improving adhesion between the functional layer and the second transparent electrode layer 12B.

The light control sheet <NUM> further includes a protective layer <NUM>. The protective layer <NUM> is located on the side of the first transparent support layer 13A facing away from the first transparent electrode layer 12A. The protective layer <NUM> is fixed to the first transparent support layer 13A via an adhesive layer (not shown).

The first surface 11F of the light control sheet <NUM> is a surface opposite to a surface of the protective layer <NUM> facing the first transparent support layer 13A. The second surface 11R of the light control sheet <NUM> is a surface opposite to a surface of the second transparent support layer 13B facing the second transparent electrode layer 12B. The second surface 11R is adhered to a transparent plate made of glass, resin, or the like via an adhesive layer (not shown). The transparent plate is, for example, a window glass of various buildings such as houses, stores, stations, and airports, a partition in offices, a display window in stores, or a window glass or a windshield of moving objects such as vehicles and aircraft. The transparent plate may have a flat surface or a curved surface.

The connection region <NUM> includes a first connection region 24A that is connected to an external wire <NUM> for applying a voltage signal to the first transparent electrode layer 12A, and a second connection region 24B that is connected to an external wire <NUM> for applying a voltage signal to the second transparent electrode layer 12B.

The first connection region 24A is a region that does not include the light control layer <NUM>, the second transparent electrode layer 12B, or the second transparent support layer 13B and in which the first transparent electrode layer 12A is exposed. A first terminal portion 50A is connected to the first transparent electrode layer 12A exposed in the first connection region 24A. That is, the driving electrode element <NUM> extends from the drive region <NUM> to the first connection region 24A, and the first terminal portion 50A is connected to the driving electrode element <NUM> in the first connection region 24A.

The second connection region 24B is a region that does not include the light control layer <NUM>, the first transparent electrode layer 12A, the first transparent support layer 13A, or the protective layer <NUM> and in which the second transparent electrode layer 12B is exposed. A second terminal portion 50B is connected to the second transparent electrode layer 12B exposed in the second connection region 24B. That is, the driving electrode element <NUM> extends from the drive region <NUM> to the second connection region 24B, and the second terminal portion 50B is connected to the driving electrode element <NUM> in the second connection region 24B.

One of the external wires <NUM> extends from the first terminal portion 50A and the other external wire <NUM> extends from the second terminal portion 50B, and the external wires <NUM> are connected to the control unit <NUM>. The control unit <NUM> applies a voltage signal to the driving electrode element <NUM> of the first transparent electrode layer 12A through the first terminal portion 50A, and applies a voltage signal to the second transparent electrode layer 12B through the second terminal portion 50B. Thus, the control unit <NUM> controls a potential difference between the first transparent electrode layer 12A and the second transparent electrode layer 12B in the drive region <NUM>. The second transparent electrode layer 12B is controlled to have, for example, a ground potential. The light control sheet <NUM> and the control unit <NUM> constitute a light control device.

The light control layer <NUM> includes a transparent polymer layer and a liquid crystal composition. The transparent polymer layer has voids in which the liquid crystal composition is filled. The liquid crystal composition is filled in the voids of the transparent polymer layer. The liquid crystal composition contains liquid crystal molecules. The liquid crystal composition may be made of a known material. The liquid crystal molecules are, for example, selected from the group consisting of those based on Schiff bases, azo types, azoxy types, biphenyls, terphenyls, benzoic acid esters, tolans, pyrimidines, cyclohexanecarboxylic acid esters, phenylcyclohexanes, and dioxanes. The light control layer <NUM> having a single-layer structure is composed of only a functional layer including a transparent polymer layer and a liquid crystal composition.

The liquid crystal composition is held in one of a polymer network type, a polymer dispersion type, and a capsule type. The polymer network type has a three-dimensional mesh transparent polymer network. Voids of the mesh communicate with each other, and a liquid crystal composition is held in the voids. The polymer network is an example of a transparent polymer layer. The polymer dispersion type has a large number of isolated voids in a transparent polymer layer, and holds a liquid crystal composition in the voids dispersed in the polymer layer. The capsule type holds an encapsulated liquid crystal composition in a transparent polymer layer. The liquid crystal composition may contain a monomer for forming a transparent polymer layer, dichroic dye, and the like, in addition to the liquid crystal molecules described above.

The first transparent electrode layer 12A and the second transparent electrode layer 12B are each conductive and transparent to light in the visible region. The first transparent electrode layer 12A and the second transparent electrode layer 12B may be made of a known material. Examples of the material for forming the first transparent electrode layer 12A and the second transparent electrode layer 12B include indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, and poly(<NUM>,<NUM>-ethylenedioxythiophene).

The first transparent support layer 13A and the second transparent support layer 13B are each a substrate transparent to light in the visible region. The first transparent support layer 13A and the second transparent support layer 13B may be made of a known material. The material for forming the first transparent support layer 13A and the second transparent support layer 13B may be, for example, a synthetic resin or an inorganic compound. Examples of the synthetic resin include polyester, polyacrylate, polycarbonate, and polyolefin. Examples of the polyester include polyethylene terephthalate and polyethylene naphthalate. The polyacrylate may be, for example, polymethyl methacrylate or the like. Examples of the inorganic compound include silicon dioxide, silicon oxynitride, and silicon nitride.

The first terminal portion 50A and the second terminal portion 50B each include, for example, a conductive adhesive layer and a circuit board. The conductive adhesive layer is composed of, for example, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), an isotropic conductive film (ICF), an isotropic conductive paste (ICP), or the like. The circuit board may be, for example, a flexible printed circuit (FPC).

Alternatively, the first terminal portion 50A and the second terminal portion 50B each may have a structure in which a conductive material such as a conductive tape is joined to the external wire <NUM> by soldering or the like.

In the drive region <NUM>, a change in the voltage generated between the two transparent electrode layers 12A and 12B causes a change in the alignment of the liquid crystal molecules in the light control layer <NUM>. The change in the alignment of the liquid crystal molecules leads to a change in the degree of scattering, degree of absorption, and degree of transmission of visible light incident on the light control layer <NUM>. Specifically, when no voltage signal is applied to the first transparent electrode layer 12A or the second transparent electrode layer 12B in the drive region <NUM>, the major axes of the liquid crystal molecules are oriented in random directions. This leads to a high degree of scattering of light incident on the light control layer <NUM>, causing the drive region <NUM> to appear turbid. That is, the drive region <NUM> is opaque when no voltage signal is applied to the light control layer <NUM>. On the other hand, when a voltage signal is applied to the transparent electrode layers 12A and 12B, and a potential difference with a predetermined value or more occurs between the first transparent electrode layer 12A and the second transparent electrode layer 12B, the liquid crystal molecules are aligned, and the major axes of the liquid crystal molecules are aligned in the direction of an electric field between the transparent electrode layers 12A and 12B. Thus, light is more likely to be transmitted through the light control layer <NUM>, and the drive region <NUM> is transparent.

<FIG> is a cross-sectional view taken along line III-III in <FIG>, and shows a cross-sectional structure of the light control sheet <NUM> in the boundary region <NUM> and in the drive region <NUM> and the floating region <NUM> between which the boundary region <NUM> is located.

As shown in <FIG>, the light control layer <NUM> includes a plurality of spacers <NUM>. The spacers <NUM> maintain an approximately constant distance between the first transparent electrode layer 12A and the second transparent electrode layer 12B. In the first transparent electrode layer 12A, the driving electrode element <NUM> is located in the drive region <NUM>, and the floating electrode element <NUM> is located in the floating region <NUM>. In other words, the driving electrode element <NUM> and the floating electrode element <NUM> are separate layered members arranged along the support surface <NUM> of the first transparent support layer 13A.

The driving electrode element <NUM> and the floating electrode element <NUM> are separated from each other by a groove <NUM>. The depth direction of the groove <NUM> is the thickness direction of the first transparent electrode layer 12A. In the present embodiment, the groove <NUM> has an opening <NUM> in a portion of the first transparent electrode layer 12A facing the light control layer <NUM>, and passes through the first transparent electrode layer 12A and extends halfway in the thickness direction of the first transparent support layer 13A. The driving electrode element <NUM> and the floating electrode element <NUM> are insulated from each other by being separated by the groove <NUM>. The boundary region <NUM> is a region in which the groove <NUM> is located.

<FIG> is an enlarged view of a cross-sectional structure of the groove <NUM> and a portion of the light control sheet <NUM> around the groove <NUM> in <FIG>. A thickness T3, which is the sum of a thickness T1 of the first transparent support layer 13A and a thickness T2 of the first transparent electrode layer 12A, is <NUM> or more and <NUM> or less. The thickness T2 of the first transparent electrode layer 12A is several tens of nanometers. The light control layer <NUM> has a thickness of <NUM> or more and <NUM> or less. The thickness of the entire light control sheet <NUM> is <NUM> or more and <NUM> or less. The thickness of the second transparent support layer 13B may be the same as or different from the thickness of the first transparent support layer 13A. Similarly, the thickness of the second transparent electrode layer 12B may be the same as or different from the thickness of the first transparent electrode layer 12A.

The depth of the groove <NUM> satisfies "T2 < D1 < T3", where "D1" is the depth of the groove <NUM>. As described above, the groove <NUM> has a depth that allows the groove <NUM> to pass through the first transparent electrode layer 12A but not to pass through the first transparent support layer 13A.

The groove <NUM> has a width W1 smaller than a diameter φ1 of the spacer <NUM> (width W1 < diameter φ1). When there is a variation in the particle diameter of the spacer <NUM>, the diameter φ1 of the spacer <NUM> is the diameter of the spacer <NUM> having the smallest particle diameter. The diameter φ1 of the spacer <NUM> is larger than the width W1 of the groove <NUM>; thus, the spacer <NUM> is less likely to enter the groove <NUM>.

<FIG> is an SEM photograph of a cross-sectional structure including the groove <NUM>. The groove <NUM> shown at the center of the photograph is opened on the light control layer <NUM> side; thus, the groove <NUM> is filled with a light control material <NUM> composed of the transparent polymer layer and the liquid crystal composition of the light control layer <NUM>. If the light control material <NUM> is not filled in the groove <NUM>, light that is transmitted through the first transparent support layer 13A and is incident on the inside of the groove <NUM> is reflected by a side surface of the groove <NUM>. In this case, the groove <NUM> is conspicuous when viewed from the outside of the light control sheet <NUM>. On the other hand, in the case where the groove <NUM> is filled with the light control material <NUM> as in the present embodiment, the groove <NUM> is less likely to be visually recognized when viewed from the outside of the light control sheet <NUM>. This is because in such a case, the side surface of the groove <NUM> has a low reflectance due to the refractive index of the material constituting the first transparent support layer 13A being closer to the refractive index of the light control material <NUM> than to the refractive index of air. Even if a small void <NUM> (see <FIG>) remains in the groove <NUM>, when most part of the groove <NUM> is filled with the light control material <NUM>, the groove <NUM> is less conspicuous. In order to obtain an effect in which the groove <NUM> is less likely to be visually recognized from the outside, the filling ratio of the light control material <NUM> in the groove <NUM> may preferably be <NUM>% or more.

As described above, the width W1 of the groove <NUM> is smaller than the diameter φ1 of the spacers <NUM>; thus, it is possible to prevent the spacers <NUM> from entering the groove <NUM> and interfere with filling of the groove <NUM> with the light control material <NUM>. Furthermore, the thickness of the light control layer <NUM> is <NUM> or more; thus, the light control material <NUM> is more likely to be filled in the groove <NUM> at a filling ratio of <NUM>% or more. Although the reason is still unknown, presumably, the light control layer <NUM> having a large thickness ensures a sufficient amount of light control material <NUM> around the opening <NUM>. Therefore, the light control material <NUM> is more likely to be filled in the groove <NUM> when a predetermined pressure is applied to the light control layer <NUM> sandwiched between the first transparent electrode layer 12A and the second transparent electrode layer 12B.

Furthermore, the first transparent electrode layer 12A has a burr <NUM> formed around the opening <NUM> of the groove <NUM>. The burr <NUM> is generated when the groove <NUM> is formed in the first transparent electrode layer 12A, and the burr <NUM> protrudes from the periphery of the opening <NUM> toward the light control layer <NUM>. When the groove <NUM> is formed, the burr <NUM> is adjusted to have a height H1 (see <FIG>) smaller than a thickness T4 (see <FIG>) of the light control layer <NUM> (H1 < T4). If the height H1 of the burr <NUM> exceeds the thickness T4 of the light control layer <NUM>, the first transparent electrode layer 12A is in contact with the second transparent electrode layer 12B via the light control layer <NUM>, causing a short circuit between the first transparent electrode layer 12A and the second transparent electrode layer 12B. The height H1 of the burr <NUM> may be <NUM> times or less of the thickness T4 of the light control layer <NUM>. In such a case, even when, for example, the light control sheet <NUM> is adhered to a curved surface or the light control sheet <NUM> is unintentionally pressed, and the distance between the first transparent electrode layer 12A and the second transparent electrode layer 12B is reduced, it is possible to sufficiently prevent a short circuit between the first transparent electrode layer 12A and the second transparent electrode layer 12B. The depth D1 of the groove <NUM> is the length of the groove <NUM> extending in the thickness direction of the first transparent electrode layer 12A from a surface of the first transparent electrode layer 12A on the light control layer <NUM> side, and does not include the height of the burr <NUM>.

Next, a method of producing the light control sheet <NUM> will be described with reference to <FIG>.

First, a film 51A including the first transparent electrode layer 12A and the first transparent support layer 13A, and a film 51B including the second transparent electrode layer 12B and the second transparent support layer 13B are prepared. Of these, a cutting plotter is brought into contact with the first transparent electrode layer 12A of the film 51A including the first transparent electrode layer 12A and the first transparent support layer 13A to form the groove <NUM>. A control device connected to the cutting plotter causes the cutting plotter to form the groove <NUM> along a design input in advance.

A device other than the cutting plotter may be used to form the groove <NUM>. For example, cutting tools other than the cutting plotter, or a laser cutting device may be used to form the groove <NUM> in the first transparent electrode layer 12A. The laser cutting device may be, for example, a laser cutter including a CO<NUM> laser.

Then, a liquid material including the spacers <NUM> containing divinylbenzene or the like as a main material and a dispersion medium for dispersing the spacers <NUM> is applied to a surface of the film 51A on the first transparent electrode layer 12A side and a surface of the film 51B on the second transparent electrode layer 12B side. Furthermore, the films on which the spacers <NUM> are scattered are heated to remove the dispersion medium. At this time, the spacers <NUM> may be scattered on only one of the films.

A light control material containing a transparent polymer material and a liquid crystal composition is applied to the first transparent electrode layer 12A of the film 51A having the groove <NUM> and to the second transparent electrode layer 12B of the film 51B having no groove <NUM>. At this time, as shown in <FIG>, the groove <NUM> may not be filled with the light control material. Furthermore, the films 51A and 51B are irradiated with ultraviolet light under a nitrogen atmosphere to form light control layers 11A and 11B, respectively. The pair of films obtained in this manner are laminated and attached together while a predetermined amount of pressure is applied to the films. Thus, the groove <NUM> is filled with the light control material.

The light control sheet <NUM> may be formed either by a roll-to-roll method or a single-sheet production process. In the roll-to-roll method, a film transferred from a roll on the upstream side is subjected to various steps and then wound around a roll on the downstream side. In the single-sheet production process, a film cut into a predetermined size is subjected to various steps. In either of the cases, the step of forming the groove <NUM> is performed before the film composed of the first transparent electrode layer 12A and the first transparent support layer 13A and the film composed of the second transparent electrode layer 12B and the second transparent support layer 13B are attached together via the light control layer <NUM>.

Then, a slit is made in a corner portion of the second surface 11R of the light control sheet <NUM> having a predetermined size, and the second transparent support layer 13B and the second transparent electrode layer 12B in the corner portion are peeled off. Furthermore, the light control layer <NUM> in the corner portion is removed to expose the first transparent electrode layer 12A to form the connection region <NUM>. Similarly, the connection region <NUM> is formed in a corner portion of the first surface 11F. Then, the first terminal portion 50A and the second terminal portion 50B are formed, and the external wires <NUM> are connected to the connection region <NUM>. Furthermore, the connection region <NUM> is sealed with an epoxy resin or the like. The step of attaching the protective layer <NUM> to the first transparent support layer 13A may be performed after the pair of films are attached together.

Thus, making a slit in the first transparent electrode layer 12A and the first transparent support layer 13A to form the groove <NUM> enables simpler formation of the groove <NUM> compared with, for example, a production method including steps such as formation of a resist mask required for patterning, exposure, development, etching, removal of the resist mask, and washing.

Next, effects of the present embodiment will be described with reference to <FIG> schematically shows the degree of transparency of the light control sheet <NUM> when the light control sheet <NUM> is not driven, that is, when no voltage signal is applied to the first transparent electrode layer 12A or the second transparent electrode layer 12B. When the light control sheet <NUM> is not driven, the drive region <NUM> and the non-driven region <NUM> are both opaque. Therefore, the entire surface of the light control sheet <NUM> appears, for example, whitish and turbid, and an image of the character, pattern, or the like composed of the non-driven region <NUM> is not visually recognized.

The groove <NUM> has a depth that allows the groove <NUM> to pass through the first transparent electrode layer 12A but not to pass through the first transparent support layer 13A; thus, the groove <NUM> is not conspicuous when viewed from either the first surface 11F or the second surface 11R of the light control sheet <NUM>. In addition, when the groove <NUM> is filled with the light control material, the groove <NUM> is even less likely to be visually recognized. This allows the light control sheet <NUM> to have a better aesthetic appearance when the design is displayed.

As shown in <FIG>, when the light control sheet <NUM> is driven, the drive region <NUM> is transparent and the non-driven region <NUM> is opaque. Therefore, only the non-driven region <NUM> appears, for example, whitish and turbid, and an image of the design such as a character or pattern composed of the non-driven region <NUM> can be visually recognized.

Thus, in the light control sheet <NUM> of the present embodiment, the surface of the light control sheet <NUM> has the regions different in light transmittance to each other, and the difference in light transmittance between the regions is shown only when the light control sheet <NUM> is driven. Therefore, when the light control sheet <NUM> is driven, an image of the character, pattern, or the like composed of the non-driven region <NUM> is visually recognized, enabling decoration of a space in which the light control sheet <NUM> is provided. Furthermore, by switching the light control sheet <NUM> between the driven state and the non-driven state, the light control sheet <NUM> can be switched between the state in which the image is displayed and the state in which the image is not displayed, enabling a dynamic change in the decoration state of the space. This allows the light control sheet <NUM> to have higher designability.

As described above, the above embodiment provides the advantages listed below.

The above embodiment can be implemented with modifications as described below. The following modifications may be implemented in combination.

· In the above embodiment, the groove <NUM> has a closed frame shape surrounding the floating electrode element <NUM>. Instead of or in addition to this, the groove <NUM> may not have a closed frame shape surrounding the floating electrode element <NUM> as long as the groove <NUM> extends along the support surface <NUM> of the first transparent support layer 13A. For example, as shown in <FIG>, when viewed from a position perpendicular to the first surface 11F, the boundary region <NUM> and the groove <NUM> may extend from a starting point located at an end portion <NUM> of the light control sheet <NUM> through an outer periphery of the floating region <NUM> and the floating electrode element <NUM> to an end point located at the end portion <NUM> of the light control sheet <NUM>. In such a case, end portions of the floating region <NUM> and the floating electrode element <NUM> are located at the end portion <NUM> of the light control sheet <NUM>. <FIG> shows the end portion <NUM> as the lower side in <FIG> of the light control sheet <NUM> having a rectangular shape; however, the end portion <NUM> serving as the starting point and the end point of the boundary region <NUM> and the groove <NUM> may be any of the upper side, left side, and right side of the light control sheet <NUM>, or may be a plurality of the sides of the light control sheet <NUM>.

· In the above embodiment, the light control sheet <NUM> is a normal-type light control sheet; however, the light control sheet <NUM> may be a reverse-type light control sheet in which when no voltage signal is applied to the light control sheet, incident light is transmitted through the light control sheet to increase translucency of the light control sheet and when a voltage signal is applied to the light control sheet, incident light is scattered to decrease translucency of the light control sheet.

<FIG> shows an example of the light control sheet <NUM> as a reverse-type light control sheet. As shown in <FIG>, the light control layer <NUM> of the light control sheet <NUM> as a reverse-type light control sheet has a multilayer structure, and includes a functional layer <NUM> including a transparent polymer layer and a liquid crystal composition, a first alignment layer <NUM>, and a second alignment layer <NUM>. The first alignment layer <NUM> and the second alignment layer <NUM> constitute the light control layer <NUM>. The first alignment layer <NUM> is located between the functional layer <NUM> and the first transparent electrode layer 12A, and is in contact with these layers. The second alignment layer <NUM> is located between the functional layer <NUM> and the second transparent electrode layer 12B, and is in contact with these layers.

The first alignment layer <NUM> and the second alignment layer <NUM> are each, for example, a vertical alignment film or a horizontal alignment film. A vertical alignment film causes the major axes of liquid crystal molecules to be aligned in the thickness direction of the light control layer <NUM>. A horizontal alignment film causes the major axes of liquid crystal molecules to be aligned in a direction substantially perpendicular to the thickness direction of the light control layer <NUM>. Thus, the first alignment layer <NUM> and the second alignment layer <NUM> control the alignment of the plurality of liquid crystal molecules contained in the light control layer <NUM>.

The material for forming each of the first alignment layer <NUM> and the second alignment layer <NUM> is an organic compound, an inorganic compound, or a mixture thereof. Examples of the organic compound include polyimide, polyamide, polyvinyl alcohol, and cyanide compounds. Examples of the inorganic compound include silicon oxide and zirconium oxide. The material for forming the first alignment layer <NUM> and the second alignment layer <NUM> may be silicone. Silicone is a compound having an inorganic portion and an organic portion.

The groove <NUM> has the opening <NUM> in a portion of the first alignment layer <NUM> facing the functional layer <NUM>, and passes through the first alignment layer <NUM> and the first transparent electrode layer 12A but does not pass through the first transparent support layer 13A. That is, the depth of the groove <NUM> is smaller than the sum of the thickness of the first alignment layer <NUM>, the thickness of the first transparent electrode layer 12A, and the thickness of the first transparent support layer 13A. The groove <NUM> is filled with a part of the functional layer <NUM>.

In the drive region <NUM> of the light control sheet <NUM> including the first alignment layer <NUM> and the second alignment layer <NUM>, when no voltage signal is applied to the transparent electrode layer 12A or 12B, the major axes of the liquid crystal molecules are aligned in the thickness direction of the light control layer <NUM>. Thus, the drive region <NUM> is transparent. On the other hand, in the drive region <NUM>, when a voltage signal is applied to the transparent electrode layers 12A and 12B, the major axes of the liquid crystal molecules are aligned in a direction intersecting the thickness direction of the light control layer <NUM>. Thus, the drive region <NUM> appears turbid and opaque. In the floating region <NUM> and the boundary region <NUM> of the light control sheet <NUM> including the first alignment layer <NUM> and the second alignment layer <NUM>, the major axes of the liquid crystal molecules are constantly aligned in the thickness direction of the light control layer <NUM>; thus, the non-driven region <NUM> is constantly transparent.

Therefore, when the light control sheet <NUM> is not driven, the drive region <NUM> and the non-driven region <NUM> are both transparent, and an image of the character, pattern, or the like composed of the non-driven region <NUM> is not visually recognized. On the other hand, when the light control sheet <NUM> is driven, the drive region <NUM> is opaque and the non-driven region <NUM> is transparent; thus, an image of the character, pattern, or the like composed of the non-driven region <NUM> can be visually recognized.

Thus, even in the light control sheet <NUM> including the first alignment layer <NUM> and the second alignment layer <NUM>, the surface of the light control sheet <NUM> has the regions different in light transmittance to each other, and the difference in light transmittance between the regions is shown only when the light control sheet <NUM> is driven. Accordingly, this allows the light control sheet <NUM> to have higher designability.

In the above aspect, the groove <NUM> passes through the first alignment layer <NUM>; however, the first alignment layer <NUM> may be formed after the groove <NUM> is formed in a laminate composed of the first transparent electrode layer 12A and the first transparent support layer 13A. In such a case, the first alignment layer <NUM> is formed along the bottom surface and side surface of the groove <NUM>. This also enables the groove <NUM> to be less conspicuous when viewed externally.

· In the above embodiment, a voltage signal is applied to the driving electrode element <NUM> which is the first electrode element, and no voltage signal is applied to the floating electrode element <NUM> which is the second electrode element. Instead, a voltage signal may be separately applied to the first electrode element and the second electrode element. In such a case, a wire for applying a voltage signal to the second electrode element is connected to an end portion of the second electrode element. A terminal portion connected to the first electrode element and a terminal portion connected to the second electrode element are different terminal portions for the respective voltage signals. As described above, in the configuration in which the second electrode element is located at the end portion of the light control sheet <NUM>, a wire is easily connected to the second electrode element.

For example, a first region in which the first electrode element is located is switched between the transparent state and the opaque state by switching the application state of a voltage signal to the first electrode element. A second region in which the second electrode element is located is switched between the transparent state and the opaque state independently from the first region by switching the application state of a voltage signal to the second electrode element. Such a configuration allows the light control sheet <NUM> to be switched among four states: the state in which the first region and the second region are both opaque, the state in which the first region is opaque and the second region is transparent, the state in which the first region is transparent and the second region is opaque, and the state in which the first region and the second region are both opaque. This enables the decoration state of the space by the light control sheet <NUM> to be more variously changed, allowing the light control sheet <NUM> to have even higher designability.

· The light transmittance of at least one of the first region and the second region may be controlled to be a light transmittance between the light transmittance at which the region is transparent and the light transmittance at which the region is opaque. In the light control sheet <NUM> including the light control layer <NUM> containing a liquid crystal composition, when the potential difference between the transparent electrode layers 12A and 12B is in a predetermined range, the light transmittance of the light control sheet <NUM> is gradually changed according to a change in the potential difference. Thus, in the first region or the second region, by controlling the potential difference between the transparent electrode layers 12A and 12B to be a value between the potential difference at which the region is transparent and the potential difference at which the region is opaque, it is possible to control the region to have a light transmittance between the light transmittance at which the region is transparent and the light transmittance at which the region is opaque, that is, it is possible to control the region to be translucent.

Claim 1:
A light control sheet (<NUM>) comprising:
a first transparent electrode layer (12A);
a second transparent electrode layer (12B);
a light control layer (<NUM>) that is located between the first transparent electrode layer (12A) and the second transparent electrode layer (12B);
a first transparent support layer (13A) that is located on a side of the first transparent electrode layer (12A) facing away from the light control layer (<NUM>) and has a support surface (<NUM>) that supports the first transparent electrode layer (12A); and
a second transparent support layer (13B) that is located on a side of the second transparent electrode layer (12B) facing away from the light control layer (<NUM>), wherein
the first transparent electrode layer (12A) includes a first electrode element (<NUM>) and a second electrode element (<NUM>),
the first electrode element (<NUM>) and the second electrode element (<NUM>) are separate layered members arranged along the support surface (<NUM>), and are electrically insulated from each other by a groove (<NUM>) extending along the support surface (<NUM>),
a depth direction of the groove (<NUM>) is a thickness direction of the first transparent electrode layer (12A), and
the groove (<NUM>) has a depth that allows the groove (<NUM>) to pass through the first transparent electrode layer (12A) but not to pass through the first transparent support layer (13A),
characterized in that
a light control material (<NUM>) constituting the light control layer (<NUM>) is filled in a portion of the groove (<NUM>) that extends in the first transparent support layer (13A).