Dimming sheet

Abstract

A light control sheet (10) is provided with: a light control layer containing a liquid crystal composition; and a first transparent electrode layer and a second transparent electrode layer which are a pair of transparent electrode layers that sandwich the light modulation layer. The dimming sheet has: a first connection region (SA) to which a wiring (61) for applying a voltage to the first transparent electrode layer is connected; and a second connection region (SB) connected to a wiring (62) for applying a voltage to the second transparent electrode layer. The first connection region and the second connection region are disposed along one side of the light control sheet when viewed from a position facing the surface of the light control sheet. Each of the first transparent electrode layer and the second transparent electrode layer has a surface resistance of 150 Omega / square or less.

Description

Technical Field

[0001] The present disclosure relates to a light modulating sheet with variable light transmittance. Background Art

[0002] The dimming sheet includes a dimming layer including a liquid crystal composition and a pair of transparent electrode layers sandwiching the dimming layer, and a driving voltage is applied between the pair of transparent electrode layers. Since the orientation state of the liquid crystal molecules changes depending on whether the driving voltage is applied, it is possible to switch between a transparent state in which light passes through the dimming layer and an opaque state in which light is scattered in the dimming layer (for example, see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-45135 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] The driving voltage is input to the dimming chip through the wiring connected to the end of the dimming chip. As the distance from the connection area, which is the area connected to the wiring, increases, the voltage applied to the dimming chip becomes lower than the input voltage to the connection area. The larger the dimming chip, the greater the voltage drop in the area farthest from the connection area, i.e., the remote area, thus causing the problem of difficulty in switching between the transparent state and the opaque state in the remote area.

[0008] If the input voltage is increased, the voltage applied to the remote area can be increased even if a voltage drop occurs, thereby suppressing the occurrence of the above-mentioned problem. However, if the input voltage is increased, the damage to the transparent electrode layer and the dimming layer becomes greater, the long-term reliability of the dimming film is reduced, and the power consumption increases, thereby increasing the environmental load.

[0009] In addition, for example, it is also considered to increase the connection area by arranging the connection areas along the two opposing sides of the dimming sheet and shorten the distance to the far end area, thereby reducing the voltage drop. However, if the connection area is increased, the number of locations where the wiring is led out from the connection area will also increase, so the design of the dimming sheet will be reduced, and the restrictions on the installation location of the dimming sheet will also increase.

[0010] In order to increase the current flowing through the dimming sheet, it is also conceivable to increase the number and size of wiring boards connected to the connection area. However, even in this case, the design of the dimming sheet is degraded.

[0011] Therefore, a new structure capable of suppressing the voltage drop is required.

[0012] Means for solving technical problems

[0013] One mode of a dimming sheet comprises: a dimming layer comprising a liquid crystal composition; and a first transparent electrode layer and a second transparent electrode layer, which are a pair of transparent electrode layers sandwiching the dimming layer. The dimming sheet comprises: a first connection region connected to a wiring for applying a voltage to the first transparent electrode layer; and a second connection region connected to a wiring for applying a voltage to the second transparent electrode layer, the first connection region and the second connection region being arranged along one side of the dimming sheet when viewed from a position opposite to the surface of the dimming sheet, and the surface resistance of each of the first transparent electrode layer and the second transparent electrode layer is 150Ω / □ or less. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a diagram showing a planar structure of a dimming sheet according to one embodiment.

[0015] Figure 2 It is a diagram showing the layer structure and electrical structure of the dimming sheet according to the above embodiment.

[0016] Figure 3 It is a diagram showing another example of the layer structure and electrical structure of the dimming sheet according to the above embodiment.

[0017] Figure 4 It is a diagram showing another example of the layer structure and electrical structure of the dimming sheet according to the above embodiment.

[0018] Figure 5 It is a diagram showing a modified example of the planar structure of the dimming sheet according to the above embodiment.

[0019] Figure 6 It is a diagram showing a modified example of the planar structure of the dimming sheet according to the above embodiment. DETAILED DESCRIPTION

[0020] An embodiment of a dimming sheet will be described with reference to the drawings.

[0021] [Structure of dimming film]

[0022] Reference Figure 1 and Figure 2 , the structure of the dimming film is explained. Figure 1 As shown in FIG. 1 , the dimming sheet 10 has a substantially rectangular shape when viewed from a position opposite to the surface of the dimming sheet 10, and includes a dimming area Si, a first connection area SA, and a second connection area SB. The dimming area Si is an area with variable transmittance, and the connection areas SA and SB are areas where wiring sections 61 and 62 for applying a driving voltage to the dimming sheet 10 are connected. The first wiring section 61 is connected to the first connection area SA, and the second wiring section 62 is connected to the second connection area SB.

[0023] The two connection areas SA and SB are located at the ends of the dimming sheet 10 and are arranged along one side of the dimming sheet 10. For example, the connection areas SA and SB are arranged near one corner of the dimming sheet 10.

[0024] Figure 2 : shows the layer structure and electrical structure of the dimming sheet 10. The dimming sheet 10 includes a dimming layer 20, a first transparent electrode layer 31, a second transparent electrode layer 32, a first transparent support layer 41, and a second transparent support layer 42. The dimming layer 20 is sandwiched between the first transparent electrode layer 31 and the second transparent electrode layer 32, and is in contact with these transparent electrode layers 31 and 32. The first transparent support layer 41 supports the first transparent electrode layer 31 on the side opposite to the dimming layer 20 relative to the first transparent electrode layer 31, and the second transparent support layer 42 supports the second transparent electrode layer 32 on the side opposite to the dimming layer 20 relative to the second transparent electrode layer 32.

[0025] The light-adjusting layer 20 includes a transparent polymer layer and a liquid crystal composition. The transparent polymer layer has voids, and the liquid crystal composition is filled in the voids. The shape of the voids is spherical, ellipsoidal, or irregular.

[0026] The liquid crystal composition in the dimming layer 20 is maintained in any of the following modes: polymer network type, polymer dispersion type, and capsule type. The polymer network type dimming layer 20 has a polymer network having a three-dimensional mesh shape. The polymer network is an example of a transparent polymer layer, and the liquid crystal composition is maintained in the gaps of the interconnected meshes in the polymer network. The polymer dispersion type dimming layer 20 has a transparent polymer layer that divides a plurality of isolated gaps, and the liquid crystal composition is maintained in the gaps dispersed in the transparent polymer layer. The capsule type dimming layer 20 maintains the liquid crystal composition in the gaps in the capsules dispersed in the transparent polymer layer.

[0027] The transparent polymer layer is a polymer of a photopolymerizable compound. The photopolymerizable compound is, for example, an ultraviolet polymerizable compound. The ultraviolet polymerizable compound is, for example, an acrylate compound such as butyl ethyl acrylate and cyclohexyl acrylate, a methacrylate compound such as N,N-dimethylaminoethyl methacrylate and phenoxyethyl methacrylate, a methacrylate compound, a stilbene compound, a diacrylate compound, a dimethacrylate compound, a triacrylate compound, a trimethacrylate compound, a tetraacrylate compound, a tetramethacrylate compound, and an oligomer of these compounds. The ratio of the transparent polymer layer to the total mass of the light-adjusting layer 20 is preferably 20% by mass or more and 80% by mass or less.

[0028] The liquid crystal composition contains, for example, liquid crystal molecules having positive dielectric anisotropy, that is, the dielectric constant in the long axis direction of the liquid crystal molecules is larger than the dielectric constant in the short axis direction of the liquid crystal molecules.

[0029] Liquid crystal molecules include, for example, Schiff base-based, azo-based, azoxy-based, biphenyl-based, terphenyl-based, benzoate-based, diphenylacetylene-based, pyrimidine-based, pyridazine-based, cyclohexanecarboxylate-based, phenylcyclohexane-based, biphenylcyclohexane-based, dicyanobenzene-based, naphthalene-based, and dioxane-based compounds.

[0030] The liquid crystal composition may contain, in addition to the liquid crystal molecules, a dichroic dye, a viscosity reducer, a defoaming agent, an antioxidant, a weathering agent, etc. An example of the weathering agent is an ultraviolet absorber or a light stabilizer.

[0031] In addition, the light-adjusting layer 20 may also include spacers dispersed throughout the entire transparent polymer layer. The spacers regulate the thickness of the light-adjusting layer 20 around the spacers, thereby making the thickness of the light-adjusting layer 20 uniform. As long as the spacers are light-transmissive, they may be bead spacers or photospacers formed by exposure and development of photoresists.

[0032] The first transparent electrode layer 31 and the second transparent electrode layer 32 are respectively conductive and transparent to light in the visible region. The transparent electrode layers 31 and 32 are made of materials such as indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, poly(3,4-ethylenedioxythiophene), silver or silver alloy.

[0033] The surface resistance of each of the first transparent electrode layer 31 and the second transparent electrode layer 32 is 150Ω / □ or less. The surface resistance is measured using a four-probe method in accordance with JIS K 7194 on the surface opposite to the surface in contact with the transparent supporting layers 41 and 42 .

[0034] The first transparent support layer 41 and the second transparent support layer 42 are substrates that are transparent to light in the visible region. The materials of the transparent support layers 41 and 42 are, for example, synthetic resins and inorganic compounds. Synthetic resins are, for example, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyacrylates such as polymethyl methacrylate, polycarbonates, polyolefins, etc. Inorganic compounds are, for example, silicon dioxide, silicon oxynitride, silicon nitride, etc.

[0035] The first wiring portion 61 is connected to the first transparent electrode layer 31 in the first connection area SA, and the second wiring portion 62 is connected to the second transparent electrode layer 32 in the second connection area SB. In the first connection area SA, the first transparent electrode layer 31 is exposed from the light-adjusting layer 20, the second transparent electrode layer 32, and the second transparent support layer 42, and in the second connection area SB, the second transparent electrode layer 32 is exposed from the light-adjusting layer 20, the first transparent electrode layer 31, and the first transparent support layer 41. Figure 2 In the figure, for convenience, the second wiring portion 62 is arranged on the side opposite to the end portion where the first wiring portion 61 is located, but the arrangement of the wiring portions 61 and 62 is as shown in FIG. Figure 1 As described.

[0036] The first wiring section 61 and the second wiring section 62 each include, for example, a conductive adhesive layer and a wiring substrate. The conductive adhesive layer may be formed, for example, of anisotropic conductive film (ACF), anisotropic conductive paste (ACP), isotropic conductive film (ICF), isotropic conductive paste (ICP), etc. The wiring substrate is, for example, a flexible printed circuit (FPC).

[0037] Alternatively, each of the first wiring portion 61 and the second wiring portion 62 may have a structure in which a conductive material such as a conductive tape and a lead wire are joined by soldering.

[0038] The transparent electrode layers 31 and 32 are electrically connected to the control unit 60 via the wiring units 61 and 62. The control unit 60 applies an AC voltage, i.e., a driving voltage, to the transparent electrode layers 31 and 32 through the wiring units 61 and 62 for changing the alignment state of the liquid crystal molecules. The control unit 60 controls the potential difference between the transparent electrode layers 31 and 32 by controlling whether or not the voltage is applied and the magnitude of the applied voltage. The dimming sheet 10, the control unit 60, and the wiring units 61 and 62 constitute a dimming device.

[0039] The dimming sheet 10 switches from a transparent state to an opaque state based on the change in the orientation state of the liquid crystal molecules. The transparent state is a state in which the light transmittance, i.e., the parallel line transmittance, is relatively high, and the opaque state is a state in which the light transmittance is relatively low. In addition, the transparent state is a state in which the haze is relatively low, and the opaque state is a state in which the haze is relatively high.

[0040] When no driving voltage is applied, the orientation of the long axis direction of the liquid crystal molecules is irregular. Therefore, due to the birefringence of the liquid crystal molecules and the refractive index difference between the liquid crystal molecules and the transparent polymer layer, the light incident on the dimming sheet 10 is scattered in various directions in the dimming layer 20. Therefore, the dimming sheet 10 becomes opaque when no driving voltage is applied.

[0041] When the dielectric anisotropy of the liquid crystal molecules is positive, the liquid crystal molecules are oriented with their long axis direction along the direction of the electric field when a driving voltage is applied. That is, the orientation of the liquid crystal molecules is changed in such a way that the long axis direction is along the thickness direction of the dimming layer 20. As a result, the scattering of light in the dimming layer 20 is suppressed, and light easily passes through the dimming sheet 10. Therefore, the dimming sheet 10 becomes transparent when a driving voltage is applied.

[0042] At least one of the front and back surfaces of the dimming sheet 10 is attached to a transparent plate formed of glass, resin, etc. The transparent plate is, for example, window glass of various buildings, partitions installed indoors, window glass and windshield glass of mobile bodies such as vehicles and aircraft. The surface of the transparent plate can be a flat surface or a curved surface.

[0043] [Characteristics of dimming film]

[0044] The equivalent circuit of the large dimming sheet 10 driven by an AC voltage is a parallel circuit of a resistor corresponding to the resistance value of the dimming layer 20 and a capacitor corresponding to the electrostatic capacitance of the dimming layer 20 connected in series between a resistor corresponding to the resistance value of the first transparent electrode layer 31 and the first wiring portion 61 and a resistor corresponding to the resistance value of the second transparent electrode layer 32 and the second wiring portion 62.

[0045] In order to suppress the voltage drop of the dimming sheet 10, it is necessary to reduce the synthetic impedance of the above circuit, but if the electrical characteristics such as electrostatic capacitance are controlled in addition to the optical characteristics of the dimming layer 20, it becomes difficult to design and manufacture the dimming layer 20. Therefore, in this embodiment, the synthetic impedance is reduced by reducing the resistance of the transparent electrode layers 31 and 32, thereby suppressing the voltage drop.

[0046] Specifically, by making the surface resistance of the transparent electrode layers 31 and 32 less than 150Ω / □, the voltage drop in the remote region, which is the region farthest from the connection regions SA and SB in the dimming sheet 10, can be preferably suppressed. As a result, the transparent state and the opaque state can be switched well in the remote region. Such an effect can be well obtained when the dimming sheet 10 is large in size, that is, when the longest side, that is, the long side, of the dimming sheet 10 is 500 mm or more, and is significant when the long side of the dimming sheet 10 is 2000 mm or more.

[0047] The surface resistance of the transparent electrode layers 31 and 32 can be changed according to the material and thickness of the transparent electrode layers 31 and 32. For example, when the material of the transparent electrode layers 31 and 32 is an oxide such as indium tin oxide, the surface resistance can be reduced by reducing the amount of oxygen. In addition, if an alloy such as a silver alloy is used as the material of the transparent electrode layers 31 and 32, the surface resistance can be made smaller than that of the transparent electrode layers 31 and 32 formed of oxides. In addition, by using a metal material such as silver as the material of the transparent electrode layers 31 and 32, infrared light can be absorbed, so a heat insulation effect can also be obtained.

[0048] In addition, the surface resistance can be reduced by increasing the thickness of the transparent electrode layers 31 and 32. The thickness of each of the first transparent electrode layer 31 and the second transparent electrode layer 32 is, for example, not less than 30 nm and not more than 200 nm.

[0049] It should be noted that in order to visually recognize the difference in transparency between the transparent state and the opaque state, the transmittance of visible light of the light modulating sheet 10 in the transparent state may be 4% or more. In addition, the visible light transmittance of the laminate of the first transparent electrode layer 31 and the first transparent supporting layer 41 and the laminate of the second transparent electrode layer 32 and the second transparent supporting layer 42 is preferably 20% or more.

[0050] However, if there are large raised portions on the surfaces of the transparent electrode layers 31 and 32, when an overvoltage is applied to the dimming sheet 10 or a high voltage is applied to the dimming sheet 10 in a test for overvoltage tolerance, a large current flows locally between the raised portion and the opposing electrode, and the raised portion may be degraded and visually recognized as a black spot. The formation of such black spots degrades the appearance quality of the dimming sheet 10, and is therefore not preferred.

[0051] The raised portion is formed, for example, due to electrical deviation or arcing in the target when the transparent electrode layers 31 and 32 are formed by sputtering. When the transparent electrode layers 31 and 32 are thickened to reduce the surface resistance, the raised portion is likely to become larger, and thus black spots are likely to be formed.

[0052] In order to suppress the formation of such black spots and thus suppress the deterioration of the appearance quality of the light control sheet 10, the maximum peak height Rp of the surface of the transparent electrode layers 31 and 32 is preferably 200 nm or less. The maximum peak height Rp is measured according to JIS B 0601 on the surface opposite to the surface in contact with the transparent supporting layers 41 and 42.

[0053] The thicker the light-adjusting layer 20 is, the more black spots can be suppressed. The thickness of the light-adjusting layer 20 is, for example, 5 μm or more and 20 μm or less. In order to appropriately suppress the formation of black spots, the thickness of the light-adjusting layer 20 is preferably 15 μm or more.

[0054] In addition, by disposing an insulating layer between the transparent electrode layers 31 and 32 and the light-adjusting layer 20, the formation of black spots can also be suppressed. Figure 3 , the structure of a dimming film including an orientation layer as an example of an insulating layer is described.

[0055] like Figure 3 As shown, the dimming sheet 11 includes a first orientation layer 51 and a second orientation layer 52 in addition to the dimming layer 20, the transparent electrode layers 31, 32, and the transparent supporting layers 41, 42. The first orientation layer 51 is located between the dimming layer 20 and the first transparent electrode layer 31, and is in contact with these layers. The second orientation layer 52 is located between the dimming layer 20 and the second transparent electrode layer 32, and is in contact with these layers.

[0056] The first alignment layer 51 and the second alignment layer 52 restrict the alignment of the liquid crystal molecules. The alignment layers 51 and 52 are, for example, vertical alignment films. The vertical alignment film aligns the liquid crystal molecules in such a way that the long axis direction thereof is along the thickness direction of the light-adjusting layer 20. When the alignment layers 51 and 52 are vertical alignment films, as the liquid crystal molecules, liquid crystal molecules having negative dielectric anisotropy, that is, liquid crystal molecules having a dielectric constant in the long axis direction smaller than that in the short axis direction, are used.

[0057] The materials of the alignment layers 51 and 52 include, for example, polyimide, polyamide, polyvinyl alcohol, organic compounds such as cyanide compounds, inorganic compounds such as silicon oxide and zirconium oxide, and organic silicon. The alignment treatment for forming the alignment layers 51 and 52 includes, for example, rubbing treatment, polarized light irradiation treatment, and microfabrication treatment.

[0058] In the dimming sheet 11, when no driving voltage is applied, the liquid crystal molecules are oriented such that their long axis directions are along the thickness direction of the dimming layer 20 due to the orientation restriction force from the orientation layers 51 and 52. As a result, the scattering of light in the dimming layer 20 is suppressed, and light easily passes through the dimming sheet 11. Therefore, the dimming sheet 11 is in a transparent state when no driving voltage is applied.

[0059] When the dielectric anisotropy of the liquid crystal molecules is negative, the long axis direction of the liquid crystal molecules is oriented in a direction orthogonal to the electric field direction when a driving voltage is applied. That is, the orientation of the liquid crystal molecules is changed in such a way that the long axis direction becomes a direction substantially orthogonal to the thickness direction of the dimming layer 20. As a result, light scattering is easily generated in the dimming layer 20. Therefore, the dimming sheet 11 becomes opaque when a driving voltage is applied.

[0060] In the dimming sheet 11, the raised portions on the surfaces of the transparent electrode layers 31 and 32 are covered by the orientation layers 51 and 52, so even when a high voltage is applied to the dimming sheet 11, it is difficult for the raised portions to deteriorate, that is, it is difficult for black spots to form. Therefore, it is possible to suppress the degradation of the appearance quality of the dimming sheet 11. In order to enhance such an effect, the thickness of each of the first orientation layer 51 and the second orientation layer 52 is preferably greater than 60 nm and less than 300 nm.

[0061] In addition, the layer structure of the dimming sheet is not limited to any of the above as long as the transparent state and the opaque state of the dimming sheet are switched based on the change in the orientation state of the liquid crystal molecules caused by the application of the driving voltage. Figure 2 , Figure 3For example, the dimming film may include a polarizing layer for controlling the polarization of incident light or transmitted light to the dimming layer 20, and the orientation layers 51 and 52 may also be horizontal orientation films. When a driving voltage is applied, whether the dimming film is in a transparent state or an opaque state can be changed according to the presence or absence of the orientation layers 51 and 52, the direction of the orientation restriction force of the orientation layers 51 and 52, the positive or negative dielectric constant anisotropy in the liquid crystal molecules, the presence or absence of the polarizing layer, etc.

[0062] In addition, in particular, when the material of the transparent electrode layers 31 and 32 is indium tin oxide, in order to reduce the surface resistance of the transparent electrode layers 31 and 32, if the amount of oxygen and the thickness of the transparent electrode layers 31 and 32 are increased, the transparent electrode layers 31 and 32 will have a yellow tint. Therefore, in order to suppress the dimming sheet from looking yellow, it is preferred to apply a transparent functional layer with a blue tint to the dimming sheet.

[0063] The transparent functional layer may be, for example, a hard coating layer arranged on the surface of the dimming film, an IR cutoff layer having the function of blocking infrared rays, an adhesive layer for bonding the hard coating layer and the IR cutoff layer to other layers of the dimming film, and an adhesive layer for bonding the first transparent supporting layer 41 or the second transparent supporting layer 42 to a transparent plate as an installation object of the dimming film.

[0064] Figure 4 FIG. 2 shows an example of a layer structure of a light-adjusting sheet 12 having a transparent functional layer. Figure 4 In the example, the transparent functional layer 70 is stacked on the first transparent supporting layer 41, but the transparent functional layer 70 only needs to be arranged at a position corresponding to the function of the transparent functional layer 70. Figure 4 In the embodiment, a structure in which the transparent functional layer 70 is stacked on the same layer structure as the dimming sheet 10 is exemplified. However, the layer structure of the dimming sheet 11 described above may be applied to a layer structure other than the transparent functional layer 70 .

[0065] The absorption bands in the visible region of the transparent electrode layers 31 and 32 are different from the absorption bands in the visible region of the transparent functional layer 70. The transparent electrode layers 31 and 32 show high absorption in the wavelength region below 500 nm, while the transparent functional layer 70 shows high absorption in the wavelength region above 600 nm.

[0066] When the colors of the transparent electrode layers 31 and 32 and the transparent functional layer 70 are expressed using the CIE 1976 (L*a*b*) colorimetric system based on JIS Z 8781 4, the chromaticity b* of the transparent electrode layers 31 and 32 is positive, and the chromaticity b* of the transparent functional layer 70 is negative.

[0067] Thus, in the transparent state, the chromaticity a* and the chromaticity b* of the dimming sheet 12 satisfy -8≤a*≤8, and -8≤b*≤8. Therefore, the dimming sheet 12 tends to look colorless. Furthermore, in the transparent state, the chromaticity a* and the chromaticity b* of the dimming sheet 12 preferably satisfy -3≤a*≤3, and -3≤b*≤3.

[0068] [Modifications]

[0069] A modification of the dimming sheet 10 will be described. In the following modification, the structure of the dimming sheet 11 or the dimming sheet 12 may also be applied.

[0070] like Figure 5 As shown, a plurality of first connection areas SA and second connection areas SB may be provided as long as they are arranged along one side of the dimming sheet 10. The first wiring sections 61 are connected to the plurality of first connection areas SA, and the second wiring sections 62 are connected to the plurality of second connection areas SB.

[0071] Even if a plurality of connection areas SA and SB are provided, as long as all the connection areas SA and SB are arranged along one side of the dimming sheet 10, wiring is led out only from the portion along the side. Therefore, compared with the case where the connection areas SA and SB are arranged along a plurality of sides, it is possible to suppress a reduction in the design of the dimming sheet 10 and a greater restriction on the installation location of the dimming sheet 10.

[0072] On the other hand, by providing a plurality of connection areas SA, SB, the distance from the connection areas SA, SB to the distal area can be shortened. Figure 1 In the case where the connection areas SA and SB are arranged near one corner of the dimming sheet 10 as shown in FIG. 1 , the area near the corner opposite to the corner is the distal area. Figure 5 In the case where the connection areas SA and SB are respectively arranged near both ends of one side of the dimming sheet 10 , an area near the center of the side facing the one side is a far-end area.

[0073] In this way, the more connection areas SA and SB there are, the shorter the distance from the connection areas SA and SB to the remote area is, so that the voltage drop in the remote area can be reduced.

[0074] like Figure 6As shown, the dimming sheet 10 may also have a shape suitable for vehicle-mounted door glass. In this case, the dimming sheet 10 has a shape that is approximately surrounded by two straight lines forming a corner and a curve connecting the ends of these straight lines and curved in a manner protruding relative to the above-mentioned corner. Furthermore, among the sides corresponding to the two straight lines, connection areas SA and SB are arranged at the above-mentioned corner along the side that extends approximately horizontally and corresponds to the lower side of the vehicle-mounted door glass. In other words, the connection areas SA and SB are arranged in the area opposite to the curved portion of the side of the dimming sheet 10.

[0075] Thus, it is possible to suppress the deviation of the distance from the connection areas SA and SB to each part of the curved side from becoming larger. Therefore, the voltage applied to the end of the dimming sheet 10 is easy to become equal, and the voltage drop in a part of the end can be suppressed from becoming larger. Therefore, the transparent state and the opaque state can be stably switched over the entire area of ​​the dimming sheet 10.

[0076] [Example]

[0077] The above-mentioned dimming sheet will be described using specific examples and comparative examples.

[0078] Regarding the relationship between the surface resistance of the transparent electrode layer and the voltage drop, dimming sheets of Examples and Comparative Examples were produced and verified.

[0079] (Example 1)

[0080] A dimming sheet having a polymer network type dimming layer is manufactured. The dimming sheet of Example 1 has Figure 2 The layer structure shown.

[0081] Specifically, an acrylic monomer as an ultraviolet polymerizable compound and a liquid crystal composition having a positive dielectric anisotropy are mixed with a polymerization initiator to prepare a coating liquid, and the coating liquid is used to form a coating film in a manner of being sandwiched between a first transparent electrode layer supported by a first transparent support layer and a second transparent electrode layer supported by a second transparent support layer. Then, ultraviolet rays are irradiated on the laminate including the coating film. As a result, the acrylic monomer in the coating film is polymerized to form a polymer network, and phase separation of the liquid crystal composition occurs, forming a dimming layer in which the liquid crystal composition is retained in the polymer network.

[0082] The material of each transparent support layer is polyethylene terephthalate. The material of each transparent electrode layer is indium tin oxide, and the surface resistance of each transparent electrode layer is 150Ω / □.

[0083] (Example 2)

[0084] The dimming sheet of Example 2 was obtained by using the same materials and processes as Example 1, except that the composition of the first transparent electrode layer and the second transparent electrode layer was changed. The material of each transparent electrode layer was indium tin oxide, and the surface resistance of each transparent electrode layer was 80Ω / □. In Example 1 and Example 2, the thickness of the transparent electrode layer was different.

[0085] (Example 3)

[0086] The dimming sheet of Example 3 was obtained by the same materials and processes as Example 1 except that the composition of the first transparent electrode layer and the second transparent electrode layer was changed. The material of each transparent electrode layer was indium tin oxide, and the surface resistance of each transparent electrode layer was 50Ω / □. In Example 1 and Example 3, the thickness of the transparent electrode layer was different.

[0087] (Example 4)

[0088] The dimming sheet of Example 4 was obtained by using the same materials and processes as Example 1 except that the composition of the first transparent electrode layer and the second transparent electrode layer was changed. The material of each transparent electrode layer was indium tin oxide, and the surface resistance of each transparent electrode layer was 30Ω / □. In Example 1 and Example 4, the thickness of the transparent electrode layer was different.

[0089] (Example 5)

[0090] The dimming sheet of Example 5 was obtained by the same materials and processes as Example 1 except that the composition of the first transparent electrode layer and the second transparent electrode layer was changed. The material of each transparent electrode layer was a silver alloy, and the surface resistance of each transparent electrode layer was 10Ω / □. In Example 1 and Example 5, the material and thickness of the transparent electrode layer were different.

[0091] (Example 6)

[0092] The dimming sheet of Example 6 was obtained by the same materials and processes as Example 1 except that the composition of the first transparent electrode layer and the second transparent electrode layer was changed. The material of each transparent electrode layer was silver alloy, and the surface resistance of each transparent electrode layer was 8Ω / □. In Example 1 and Example 6, the material and thickness of the transparent electrode layer were different.

[0093] (Example 7)

[0094] The dimming sheet of Example 7 was obtained by the same materials and processes as Example 1 except that the composition of the first transparent electrode layer and the second transparent electrode layer was changed. The material of each transparent electrode layer was silver nanowire, and the surface resistance of each transparent electrode layer was 30Ω / □. In Example 1 and Example 7, the material and thickness of the transparent electrode layer were different.

[0095] (Comparative Example 1)

[0096] The dimming sheet of Comparative Example 1 was obtained by the same materials and processes as Example 1 except that the composition of the first transparent electrode layer and the second transparent electrode layer was changed. The material of each transparent electrode layer was indium tin oxide, and the surface resistance of each transparent electrode layer was 300Ω / □. In Example 1 and Comparative Example 1, the thickness of the transparent electrode layer was different.

[0097] (Comparative Example 2)

[0098] Except for changing the composition of the first transparent electrode layer and the second transparent electrode layer, the dimming sheet of Comparative Example 2 was obtained by the same materials and processes as Example 1. The material of each transparent electrode layer was poly(3,4-ethylenedioxythiophene), and the surface resistance of each transparent electrode layer was 170Ω / □. In Example 1 and Comparative Example 2, the material and thickness of the transparent electrode layer were different.

[0099] (Evaluation method)

[0100] <Voltage Drop Measurement>

[0101] The dimming sheets of each example and each comparative example were molded into a rectangular shape with a short side of 1000 mm and a long side of 3000 mm, and voltage drop measurements were performed under two conditions, Condition 1 and Condition 2.

[0102] In condition 1, a first connection area and a second connection area are formed at the corners along one short side to connect the first wiring section and the second wiring section. As the wiring section, an FPC with a width of 50 mm is used. Then, the corner opposite to the corner where the connection area is arranged is used as the measurement target area.

[0103] In condition 2, along one short side, a first connection area and a second connection area are formed at the corners of one end of the short side, and further, a first connection area and a second connection area are formed at the corners of the other end of the short side. Then, the first wiring section is connected to each first connection area, and the second wiring section is connected to each second connection area. As the wiring section, an FPC with a width of 50 mm is used. Then, the central part of the short side opposite to the short side with the connection area is used as the measurement object area.

[0104] As described above, in condition 1, the voltage is input from two poles, and in condition 2, the voltage is input from four poles.

[0105] In the voltage drop measurement, the effective voltage in the connection area and the effective voltage in the measurement target area when each input voltage is input are measured. The input voltage is an AC voltage, and the effective voltage in the connection area is set to a 20V interval within a range of 40V or more and 120V or less. Then, for each input voltage, the voltage drop rate is calculated according to the following (Formula 1), and the average value of the voltage drop rate of each input voltage is taken as the voltage drop rate Dr of each embodiment. That is, the voltage drop rate is the percentage of the difference between the effective voltage of the connection area and the measurement target area relative to the effective voltage of the connection area.

[0106] Voltage drop rate (%) = (effective voltage of the connection area - effective voltage of the measurement target area) × 100 / effective voltage of the connection area (Formula 1)

[0107] <Driver Confirmation>

[0108] The input voltage as the AC voltage was set so that the effective voltage in the connection area became 80 V. For each embodiment and each comparative example, when the input voltage was switched on and off, it was visually confirmed whether the transparent state and the opaque state could be switched over the entire area of ​​the dimming sheet. In the evaluation, the case where the transparent state and the opaque state could be switched over the entire area of ​​the dimming sheet was marked as "○", and the case where there was an area in the dimming sheet where the transparent state and the opaque state could not be switched was marked as "×".

[0109] (Evaluation results)

[0110] Table 1 shows the surface resistance of the transparent electrode layer, the light transmittance of the laminate of the transparent electrode layer and the transparent supporting layer, the voltage drop rate Dr under Condition 1 and Condition 2, and the evaluation results of the driving confirmation for each Example and each Comparative Example.

[0111] Table 1

[0112]

[0113] As shown in Table 1, the distance between the connection area and the measurement target area is shorter in Condition 2 than in Condition 1, so the voltage drop rate is smaller. As shown in Examples 1 to 7, if the surface resistance of the transparent electrode layer is 150Ω / □ or less, the voltage drop rate Dr is suppressed to less than 50% even in Condition 1, and the transparent state and the opaque state can be switched over the entire area of ​​the dimming sheet.

[0114] On the other hand, as shown in Comparative Examples 1 and 2, when the voltage drop rate Dr exceeds 75%, the switching between the transparent state and the opaque state does not occur in the vicinity of the measurement target region.

[0115] Regarding the formation of black spots when a high voltage is applied, a dimming sheet of a test example was prepared and verified.

[0116] (Test Example 1)

[0117] A dimming sheet having a polymer network type dimming layer was prepared. The dimming sheet of Experimental Example 1 has Figure 2 The layer structure shown.

[0118] Specifically, an acrylic monomer as an ultraviolet polymerizable compound and a liquid crystal composition having a positive dielectric anisotropy are mixed with a polymerization initiator to prepare a coating liquid, and the coating liquid is used to form a coating film in a manner of being sandwiched between a first transparent electrode layer supported by a first transparent support layer and a second transparent electrode layer supported by a second transparent support layer. Then, ultraviolet rays are irradiated on the laminate including the coating film. As a result, the acrylic monomer in the coating film is polymerized to form a polymer network, and phase separation of the liquid crystal composition occurs, forming a dimming layer in which the liquid crystal composition is retained in the polymer network. The thickness of the dimming layer is 5 μm.

[0119] The material of each transparent support layer is polyethylene terephthalate. The material of each transparent electrode layer is indium tin oxide, and the maximum peak height Rp of each transparent electrode layer is 15 nm.

[0120] (Test Example 2)

[0121] A dimming sheet of Experimental Example 2 was obtained by the same materials and steps as Experimental Example 1 except that transparent electrode layers with different surface roughness were used. In Experimental Example 2, the thickness of the dimming layer was 5 μm, and the maximum peak height Rp of each transparent electrode layer was 80 nm.

[0122] (Test Example 3)

[0123] A dimming sheet of Test Example 3 was obtained by the same materials and steps as Test Example 1 except that transparent electrode layers with different surface roughness were used. In Test Example 3, the thickness of the dimming layer was 5 μm, and the maximum peak height Rp of each transparent electrode layer was 180 nm.

[0124] (Test Example 4)

[0125] The dimming sheet of Experimental Example 4 was obtained by the same materials and processes as Experimental Example 1, except that transparent electrode layers with different surface roughness were used and the thickness of the dimming layer was changed. In Experimental Example 4, the thickness of the dimming layer was 20 μm, and the maximum peak height Rp of each transparent electrode layer was 320 nm.

[0126] (Test Example 5)

[0127] A dimming sheet of Test Example 5 was obtained by the same materials and steps as Test Example 1 except that transparent electrode layers with different surface roughness were used. In Test Example 5, the thickness of the dimming layer was 5 μm, and the maximum peak height Rp of each transparent electrode layer was 320 nm.

[0128] (Test Example 6)

[0129] The dimming sheet of Experimental Example 6 was obtained by the same materials and processes as Experimental Example 1 except that transparent electrode layers with different surface roughness were used and the thickness of the dimming layer was changed. In Experimental Example 6, the thickness of the dimming layer was 20 μm, and the maximum peak height Rp of each transparent electrode layer was 520 nm.

[0130] [Test Example 7]

[0131] A dimming sheet of Test Example 7 was obtained by the same materials and steps as Test Example 1 except that transparent electrode layers with different surface roughness were used. In Test Example 7, the thickness of the dimming layer was 5 μm, and the maximum peak height Rp of each transparent electrode layer was 520 nm.

[0132] (High voltage application test)

[0133] A high voltage test voltage was applied to the dimming sheets of Test Examples 1 to 7, and it was visually confirmed whether black spots were formed in the dimming sheets after the application. The case where no black spots were observed was evaluated as "○", the case where 1 to 5 black spots were observed was evaluated as "△", and the case where 6 or more black spots were observed was evaluated as "×". The area of ​​the dimming sheet of each test example was 7.0×10 5 mm 2 .

[0134] (Test results)

[0135] Table 2 shows the maximum peak height Rp of the transparent electrode layer, the thickness of the light-adjusting layer, the test voltage, and the test results for Test Examples 1 to 7.

[0136] Table 2

[0137]

[0138] As shown in Table 2, in Test Examples 6 and 7 where the maximum peak height Rp was 520 nm, black spots were observed both when the thickness of the dimming layer was 20 μm and when it was 5 μm. On the other hand, in Test Examples 4 and 5 where the maximum peak height Rp was 320 nm, no black spots were observed when the thickness of the dimming layer was 20 μm, but black spots were observed when the thickness of the dimming layer was 5 μm. Furthermore, in Test Examples 1 to 3 where the maximum peak height Rp was less than 200 nm, no black spots were observed when the thickness of the dimming layer was 5 μm.

[0139] From the above, it was confirmed that the thicker the dimming layer, the greater the maximum peak height Rp of the transparent electrode layer, the less the formation of black spots can be. However, if the maximum peak height Rp is 200 nm or less, the less the formation of black spots can be.

[0140] (Test Example 11)

[0141] A dimming sheet having a polymer network type dimming layer was prepared. The dimming sheet of Experimental Example 11 has Figure 2 The layer structure shown.

[0142] Specifically, an acrylic monomer as an ultraviolet polymerizable compound and a liquid crystal composition having a positive dielectric anisotropy are mixed with a polymerization initiator to prepare a coating liquid, and the coating liquid is used to form a coating film in a manner sandwiched between a first transparent electrode layer supported by a first transparent support layer and a second transparent electrode layer supported by a second transparent support layer. Then, ultraviolet rays are irradiated to the laminate including the coating film. Thus, the acrylic monomer in the coating film is polymerized to form a polymer network, and phase separation of the liquid crystal composition occurs, forming a dimming layer in which the liquid crystal composition is retained in the polymer network. The thickness of the dimming layer is 5 μm. The material of each transparent support layer is polyethylene terephthalate. The material of each transparent electrode layer is indium tin oxide.

[0143] (Test Examples 12 and 13)

[0144] The dimming sheets of Experimental Examples 12 and 13 were obtained by the same materials and processes as those of Experimental Example 11, except that an alignment layer was formed on each transparent electrode layer and a coating film was sandwiched between the first alignment layer and the second alignment layer. It should be noted that a liquid crystal composition having a negative dielectric anisotropy was used as the liquid crystal composition. The dimming sheets of Experimental Examples 12 and 13 have Figure 3 The layer structure shown in FIG.

[0145] (Test Example 14)

[0146] A dimming sheet of Test Example 14 was obtained by using the same materials and steps as those of Test Example 11 except that the thickness of the dimming layer was changed to 7 μm.

[0147] (Test Example 15)

[0148] The dimming sheet of Experimental Example 15 was obtained by the same materials and processes as those of Experimental Example 11, except that an alignment layer was formed on each transparent electrode layer, the dimming layer was sandwiched between the first alignment layer and the second alignment layer, and the thickness of the dimming layer was changed to 7 μm. It should be noted that a liquid crystal composition having a negative dielectric anisotropy was used as the liquid crystal composition. The dimming sheet of Experimental Example 15 has Figure 3 The layer structure shown in FIG.

[0149] (Test Example 16)

[0150] A dimming sheet of Test Example 16 was obtained by using the same materials and steps as those of Test Example 11 except that the thickness of the dimming layer was changed to 16 μm.

[0151] (Test Example 17)

[0152] A dimming sheet of Test Example 17 was obtained by following the same materials and steps as those of Test Example 11 except that the thickness of the dimming layer was changed to 20 μm.

[0153] (High voltage application test)

[0154] A high voltage test voltage was applied to the dimming sheets of Test Examples 11 to 17, and it was visually confirmed whether black spots were formed in the dimming sheets after the application. The case where no black spots were observed was evaluated as "○", the case where 1 to 5 black spots were observed was evaluated as "△", and the case where 6 or more black spots were observed was evaluated as "×". The area of ​​the dimming sheet of each test example was 7.0×10 5 mm 2 .

[0155] (Test results)

[0156] Table 3 shows the thickness of the light-adjusting layer, the presence or absence of an alignment layer, the test voltage, and the test results for Test Examples 11 to 17.

[0157] Table 3

[0158]

[0159] As shown in Table 3, in Test Examples 11 to 13 where the thickness of the light-adjusting layer was 5 μm, the generation of black spots was suppressed when the alignment layer was provided. Also, in Test Examples 14 and 15 where the thickness of the light-adjusting layer was 7 μm, the generation of black spots was suppressed when the alignment layer was provided.

[0160] Comparing Test Examples 11, 14, 16, and 17 without an alignment layer, the thicker the light-adjusting layer, the more black spots are suppressed when a higher voltage is applied. If the thickness of the light-adjusting layer is 15 μm or more, the generation of black spots can be appropriately suppressed even when a high voltage of 200 V is applied.

[0161] In addition, when comparing the test examples 12, 13, and 15 in which the orientation layer is provided, in this case as well, the thicker the light-adjusting layer, the more the generation of black spots is suppressed when a higher voltage is applied. If the thickness of the light-adjusting layer is 7 μm or more, the generation of black spots can be appropriately suppressed even when a high voltage of 200 V is applied.

[0162] As described above in the embodiments and examples, according to the above-mentioned dimming sheet, the following effects can be obtained.

[0163] (1) The surface resistance of the transparent electrode layers 31 and 32 is 150Ω / □ or less. This can suppress voltage drop, and thus the transparent state and the opaque state can be switched satisfactorily over a wide range of the dimming sheet.

[0164] (2) When the maximum peak height Rp on the surface of the transparent electrode layers 31 and 32 is 200 nm or less, the ridges on the surface of the transparent electrode layers 31 and 32 are prevented from being degraded and forming black spots when a high voltage is applied. Therefore, the appearance quality of the dimming sheet can be prevented from being degraded.

[0165] (3) Since the insulating layer is provided between the light-adjusting layer 20 and the transparent electrode layers 31 and 32 , even when the light-adjusting layer 20 is thin, the formation of black spots can be suppressed when a high voltage is applied.

[0166] (4) By providing the transparent functional layer 70, the chromaticity b* of the transparent electrode layers 31 and 32 is positive, and the chromaticity b* of the transparent functional layer 70 is negative. As a result, the influence of the transparent electrode layers 31 and 32 having a yellow tint is compensated by the transparent functional layer 70 having a blue tint, so that the dimming sheet tends to look colorless in a transparent state.

[0167] (5) When the dimming sheet has a shape suitable for vehicle door glass, the connection areas SA and SB are arranged at positions corresponding to the corners of the vehicle door glass along the side corresponding to the lower side of the vehicle door glass. As a result, the deviation of the distance from the connection areas SA and SB to each part of the curved side can be suppressed from becoming larger, so the voltage applied to the end of the dimming sheet is easy to become equal, and the voltage drop at a part of the end can be suppressed from becoming larger. Therefore, the transparent state and the opaque state can be stably switched over a wide range of the dimming sheet.

Claims

1. A dimming film, comprising: a dimming layer comprising a liquid crystal composition; and The first transparent electrode layer and the second transparent electrode layer are a pair of transparent electrode layers sandwiching the light-adjusting layer. in, The dimming film has: a first connection region connected to a wiring for applying a voltage to the first transparent electrode layer; as well as a second connection region connected to a wiring for applying a voltage to the second transparent electrode layer; When viewed from a position facing the surface of the dimming sheet, the first connection region and the second connection region are arranged along one side of the dimming sheet. The first transparent electrode layer and the second transparent electrode layer each have a surface resistance of 150Ω / □ or less.

2. The dimming sheet according to claim 1, wherein: The maximum peak height Rp on the surface of each of the first transparent electrode layer and the second transparent electrode layer is 200 nm or less.

3. The dimming sheet according to claim 1, wherein: A pair of insulating layers is provided between the light-adjusting layer and the pair of transparent electrode layers.

4. The dimming sheet according to claim 1, wherein: The dimming sheet has a shape suitable for vehicle door glass. The first connection region and the second connection region are arranged at positions corresponding to corners of the vehicle door glass along a side corresponding to a lower side of the vehicle door glass.

5. The dimming sheet according to claim 1, wherein: The dimming film also has a transparent functional layer. The absorption bands of the first transparent electrode layer and the second transparent electrode layer in the visible region are different from the absorption band of the transparent functional layer in the visible region. In the CIE 1976 (L*a*b*) colorimetric system, the chromaticity b* of each transparent electrode layer is positive, and the chromaticity b* of the transparent functional layer is negative.

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