Screen system

Abstract

To provide a dimming device, a screen system, a dimming window, and a dimming sheet that can perform switching of optical characteristics different from switching between a transmission state and a scattering state.SOLUTION: A dimming device 100 comprises a sheet unit 10 which comprises dimming sheets 11, 12 and a control part 60 which controls application of a voltage to the sheet unit 10. Processing that the control part 60 executes comprises: placing the dimming sheets 11, 12 in a first state in which visible light is reflected by controlling the voltage between transparent electrode layers 31, 32 to a first voltage; placing the dimming sheets 11, 12 in a second state in which visible light is scattered by controlling the voltage between transparent electrode layers 31, 32 to a second voltage; and placing the dimming sheets 11, 12 in a third state in which the visible light is transmitted by controlling the voltage between transparent electrode layers 31, 32 to a third voltage.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to ,vinegar a clean system Mu .

Background Art

[0002] The dimming sheet includes a dimming layer containing 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 alignment state of the liquid crystal molecules changes according to the presence or absence of the application of the driving voltage, it is possible to switch between a transmission state in which light passes through the dimming layer and a scattering state in which light is scattered by the dimming layer (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above dimming sheet is attached to a transparent plate that functions as a window glass, partition, or the like. By switching between the transmission state and the scattering state, it is possible to switch between a state where the visibility behind the transparent plate is high and a state where the visibility behind the transparent plate is low. On the other hand, in the dimming sheet, if it is possible to switch between optical characteristics different from the switching between the transmission state and the scattering state, a dimming sheet having a function different from the switching between high and low visibility can be realized, and thus the development of new uses of the dimming sheet can be expected.

Means for Solving the Problems

[0005] A dimming device for solving the above problems is a dimming device comprising a dimming sheet and a control unit for controlling the application of voltage to the dimming sheet, wherein the dimming sheet comprises a first transparent electrode layer, a second transparent electrode layer, and a dimming layer located between the first transparent electrode layer and the second transparent electrode layer, the dimming layer comprising a transparent polymer layer separating a plurality of voids, and a liquid crystal composition which is a chiral nematic liquid crystal having positive dielectric anisotropy and is held in the voids, and the processing performed by the control unit includes controlling the voltage between the first transparent electrode layer and the second transparent electrode layer to a first voltage to put the dimming sheet into a first state that reflects visible light, and controlling the voltage between the first transparent electrode layer and the second transparent electrode layer to a third voltage greater than the first voltage to put the dimming sheet into a third state that transmits visible light.

[0006] A dimming sheet for solving the above problems comprises a first transparent electrode layer, a second transparent electrode layer, and a dimming layer located between the first transparent electrode layer and the second transparent electrode layer, the dimming layer comprising a transparent polymer layer separating a plurality of voids, and a liquid crystal composition having positive dielectric anisotropy and held in the voids, wherein the space between the first transparent electrode layer and the second transparent electrode layer is controlled to a first voltage, the liquid crystal composition exhibiting a planar state in a first state, the dimming sheet reflecting visible light in the first state, and the first transparent electrode layer The liquid crystal composition includes a second state in which the liquid crystal composition exhibits a focal conic state and the dimming sheet scatters visible light, by controlling the voltage between the first transparent electrode layer and the second transparent electrode layer to a second voltage greater than the first voltage, and a third state in which the liquid crystal composition exhibits a homeotropic state and the dimming sheet transmits visible light, wherein the helical pitch P (μm), the ordinary refractive index no, and the extraordinary refractive index ne of the liquid crystal composition satisfy the following equation (1): 0.4 ≤ P × (ne + 2no) / 3 ≤ 0.8 ···(1)

[0007] According to the above configurations, by utilizing the selective reflection of chiral nematic liquid crystals, the dimming sheet can be switched between a state that reflects visible light and a transparent state. This allows for a switch in optical properties that differs from switching between a transmission state and a scattering state, enabling the dimming sheet to be used in new applications such as screen systems for reflective projection systems or dimmable windows that can block light.

[0008] In the above-described dimming device, the processing performed by the control unit may further include controlling the voltage between the first transparent electrode layer and the second transparent electrode layer to a second voltage that is greater than the first voltage and less than the third voltage, thereby putting the dimming sheet into a second state that scatters visible light. According to the above configuration, the dimming sheet can be switched between a state that reflects visible light, a cloudy state, and a transparent state. Therefore, it becomes possible to switch between a wider variety of effects that the dimming sheet has on the space.

[0009] In the above-described dimming device, the helical pitch P (μm), the ordinary refractive index no, and the extraordinary refractive index ne of the liquid crystal composition in the dimming sheet may satisfy the following formula (1): 0.4 ≤ P × (ne + 2no) / 3 ≤ 0.8 ···(1) According to the above configuration, the reflection wavelength of the liquid crystal composition, which is a chiral nematic liquid crystal, is precisely set to the visible region. Therefore, visible light is precisely reflected by the dimming sheet in the first state.

[0010] In the above-described dimming device, the proportion of the region in the dimming layer where the liquid crystal molecules contained in the liquid crystal composition are horizontally oriented in the first state of the dimming sheet may be 50% or more. According to the above configuration, a good reflectivity of visible light can be obtained in the dimming sheet in the first state.

[0011] In the above-described dimming device, the proportion of the transparent polymer layer in the dimming layer of the dimming sheet may be less than 50%. With the above configuration, a sufficient proportion of the liquid crystal composition is ensured in the dimming layer, so that a good reflectivity of visible light can be obtained in the dimming sheet in the first state.

[0012] In the above-described dimming device, the refractive index np of the polymer material constituting the transparent polymer layer in the dimming sheet and the ordinary refractive index no of the liquid crystal composition may satisfy the following formula (2): 0.98 ≤ np / no ≤ 1.02 ···(2) According to the above configuration, in the dimming sheet in the third state, visible light can more easily travel in a straight line through the dimming layer, thereby increasing the transmittance of visible light.

[0013] In the above-described dimming device, the dimming sheet comprises a first orientation layer sandwiched between the first transparent electrode layer and the dimming layer, and a second orientation layer sandwiched between the second transparent electrode layer and the dimming layer, wherein each of the first orientation layer and the second orientation layer may be a horizontally oriented film. According to the above configuration, the proportion of liquid crystal molecules that are horizontally aligned in the first state can be increased. Therefore, the reflectivity of visible light can be increased in the dimming sheet in the first state.

[0014] The above-described dimming device comprises two dimming sheets, a first dimming sheet and a second dimming sheet, wherein the optical rotation of the liquid crystal composition contained in the first dimming sheet and the optical rotation of the liquid crystal composition contained in the second dimming sheet are different from each other, the first dimming sheet and the second dimming sheet are arranged to overlap in the thickness direction, and the processing performed by the control unit may include setting each of the first dimming sheet and the second dimming sheet to the first state.

[0015] According to the above configuration, by setting the two dimming sheets to the first state, different circularly polarized light components are reflected from these dimming sheets, so that more components of the light irradiated onto the unit consisting of these dimming sheets are reflected. Therefore, the intensity of the reflected light is increased, and the transmission of light through the unit of dimming sheets can be further suppressed.

[0016] In the above configuration, the processing performed by the control unit may further include at least one of the following: setting each of the first dimming sheet and the second dimming sheet to a second state in which visible light is scattered by controlling the voltage between the first transparent electrode layer and the second transparent electrode layer to a second voltage that is greater than the first voltage and less than the third voltage; and setting each of the first dimming sheet and the second dimming sheet to the third state.

[0017] According to the above configuration, the dimming sheet unit can be switched between a state that reflects visible light and at least one of a cloudy state and a transparent state. Therefore, it becomes possible to switch between a wider variety of effects that the dimming sheet has on the space.

[0018] A screen system for solving the above problems is a screen system including the dimming device, having a screen equipped with the dimming sheet, and an image is projected onto the dimming sheet in the first state. According to the above configuration, the dimming sheet in the first state can be used as a screen for a reflective projection system.

[0019] A screen system for solving the above problems is a screen system including the above-mentioned dimming device, comprising: a screen having a first dimming sheet and a second dimming sheet; a first projection device that irradiates light toward the first dimming sheet; and a second projection device that irradiates light toward the second dimming sheet from the opposite side of the screen from the first projection device.

[0020] According to the above configuration, a unit consisting of two dimmable sheets can be used as the screen for a reflective projection system. Using this single screen unit of dimmable sheets, images can be projected into each of the two spaces flanking the screen. Therefore, efficient use of space is possible while simplifying the equipment.

[0021] The dimming window for solving the above problems includes the above dimming device and is provided with a window to which the dimming sheet is attached. According to the above configuration, a dimming window capable of switching between a light-shielding state and other states can be realized.

Effect of the Invention

[0022] According to the present invention, in the dimming sheet, switching of optical characteristics different from switching between a transmission state and a scattering state can be performed.

Brief Description of the Drawings

[0023] [Figure 1] A diagram showing the configuration of a dimming device according to an embodiment. [Figure 2] A diagram showing the structure of the dimming sheet in the first state included in the dimming device according to the above embodiment. [Figure 3] A diagram showing the structure of the dimming sheet in the second state included in the dimming device according to the above embodiment. [Figure 4] A diagram showing the structure of the dimming sheet in the third state included in the dimming device according to the above embodiment. [Figure 5] A diagram showing a typical example of the relationship between the applied voltage and the transmittance of infrared light for the dimming sheet included in the dimming device according to the above embodiment. [Figure 6] A diagram showing the usage form of a screen system to which the dimming device according to the above embodiment is applied, showing the case when the sheet unit is in the first state. [Figure 7] A diagram showing the usage form of a screen system to which the dimming device according to the above embodiment is applied, showing the case when the sheet unit is in the second state. [Figure 8] A diagram showing the usage form of a screen system to which the dimming device according to the above embodiment is applied, showing the case when the sheet unit is in the third state. [Figure 9] A diagram showing the usage form of a dimming window to which the dimming device according to the above embodiment is applied, showing the case when the sheet unit is in the first state. [Figure 10] A diagram showing the reflection characteristics of two dimming sheets included in the sheet unit of the example. [Modes for carrying out the invention]

[0024] An embodiment of a dimming device and a dimming sheet will be described with reference to Figures 1 to 9. In the following description, visible light refers to light in the wavelength range of 360 nm to 800 nm. [Configuration of the dimmer] As shown in Figure 1, the dimming device 100 comprises a sheet unit 10 and a control unit 60. The sheet unit 10 comprises a first dimming sheet 11 and a second dimming sheet 12. The control unit 60 controls the application of voltage to the dimming sheets 11 and 12.

[0025] The first dimming sheet 11 and the second dimming sheet 12 are arranged to overlap in the thickness direction. The first dimming sheet 11 and the second dimming sheet 12 may be in contact or separated. For example, the first dimming sheet 11 is attached to the surface of the transparent plate 110, and the second dimming sheet 12 is attached to the back surface of the transparent plate 110.

[0026] The transparent panel 110 is formed from glass, resin, or the like. Examples of transparent panels 110 include window glass in various buildings such as houses, train stations, and airports, partitions installed in offices, and display windows installed in stores.

[0027] Furthermore, the configuration is not limited to the above; the first dimming sheet 11 and the second dimming sheet 12 may be attached to separate transparent plates, or they may be laminated on one surface of a single transparent plate.

[0028] [Configuration of the dimming sheet] The detailed configuration of dimming sheets 11 and 12 will be explained with reference to Figures 2 to 5. In the following explanation, the first dimming sheet 11 will be used as an example.

[0029] As shown in Figure 2, the dimming sheet 11 comprises a dimming layer 20, a pair of transparent electrode layers 31 and 32, a pair of transparent support layers 41 and 42, and a pair of orientation layers 51 and 52. The pair of transparent electrode layers 31 and 32 are the first transparent electrode layer 31 and the second transparent electrode layer 32, the pair of transparent support layers 41 and 42 are the first transparent support layer 41 and the second transparent support layer 42, and the pair of orientation layers are the first orientation layer 51 and the second orientation layer 52.

[0030] The dimming layer 20 is sandwiched between the first transparent electrode layer 31 and the second transparent electrode layer 32. A first alignment layer 51 is located between the dimming layer 20 and the first transparent electrode layer 31, and the first alignment layer 51 is in contact with the dimming layer 20 and the first transparent electrode layer 31. A second alignment layer 52 is located between the dimming layer 20 and the second transparent electrode layer 32, and the second alignment layer 52 is in contact with the dimming layer 20 and the second transparent electrode layer 32. A first transparent support layer 41 supports the first transparent electrode layer 31 on the side opposite to the dimming layer 20, and a second transparent support layer 42 supports the second transparent electrode layer 32 on the side opposite to the dimming layer 20.

[0031] The light-adjusting layer 20 comprises a transparent polymer layer 21 and a liquid crystal composition which is a chiral nematic liquid crystal. The liquid crystal composition contains liquid crystal molecules 23. The transparent polymer layer 21 divides a plurality of voids 22, and the liquid crystal composition is held within the voids 22. The liquid crystal composition has positive dielectric anisotropy. That is, the dielectric constant in the long axis direction of the liquid crystal molecules 23 is greater than the dielectric constant in the short axis direction of the liquid crystal molecules 23.

[0032] Examples of liquid crystal molecules 23 include Schiff base-based, azo-based, azoxy-based, biphenyl-based, terphenyl-based, benzoic acid ester-based, tran-based, pyrimidine-based, cyclohexanecarboxylic acid ester-based, phenylcyclohexane-based, and dioxane-based liquid crystal molecules. Furthermore, an example of a chiral agent contained in a liquid crystal composition is an optically active low-molecular-weight compound having one or more chiral carbon atoms.

[0033] The structure of the transparent polymer layer 21 and the type of holding the liquid crystal composition are, for example, polymer network type, polymer dispersion type, and capsule type. The polymer network type light-adjusting layer 20 comprises a polymer network having a three-dimensional mesh structure. The polymer network is an example of a transparent polymer layer, and the liquid crystal composition is held in the interconnected voids within the mesh of the polymer network. The polymer dispersion type light-adjusting layer 20 comprises a transparent polymer layer that partitions a number of isolated voids, and the liquid crystal composition is held in the voids dispersed in the transparent polymer layer. The capsule type light-adjusting layer 20 holds the liquid crystal composition in the voids within capsules dispersed in the transparent polymer layer.

[0034] Each of the first transparent electrode layer 31 and the second transparent electrode layer 32 is formed from a conductive material and is transparent to visible light. Known materials can be used for the transparent electrode layers 31 and 32. Examples of materials for the transparent electrode layers 31 and 32 include indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, poly(3,4-ethylenedioxythiophene), silver, and silver alloys.

[0035] Each of the first transparent support layer 41 and the second transparent support layer 42 is a substrate that is transparent to visible light. Known materials can be used for the transparent support layers 41 and 42. The materials for the transparent support layers 41 and 42 may be synthetic resins or inorganic compounds. Examples of synthetic resins include polyester, polyacrylate, polycarbonate, and polyolefin. Examples of polyester include polyethylene terephthalate and polyethylene naphthalate. Examples of polyacrylate include polymethyl methacrylate. Examples of inorganic compounds include silicon dioxide, silicon oxynitride, and silicon nitride.

[0036] Each of the first alignment layer 51 and the second alignment layer 52 is a horizontal alignment film. The horizontal alignment film aligns the liquid crystal molecules 23 such that the long axis of the liquid crystal molecules 23 is aligned horizontally along the surface of the alignment film. The materials of the alignment layers 51 and 52 are organic compounds, inorganic compounds, and mixtures thereof. Examples of organic compounds include polyimide, polyamide, polyvinyl alcohol, cyanide compounds, etc. Examples of inorganic compounds include silicon oxide, zirconium oxide, etc. The material of the alignment layers 51 and 52 may also be silicone. Silicone is a compound having an inorganic part and an organic part.

[0037] The control unit 60 is connected to the first transparent electrode layer 31 and the second transparent electrode layer 32 via wiring. The control unit 60 generates a voltage for driving the dimming sheet 11 and applies the generated voltage to the transparent electrode layers 31 and 32 through the wiring. By controlling whether or not the voltage is applied and controlling the magnitude of the applied voltage, the control unit 60 controls the magnitude of the voltage between the transparent electrode layers 31 and 32.

[0038] The control unit 60 controls the voltage between the transparent electrode layers 31 and 32 to one of the following: a first voltage V1, a second voltage V2, and a third voltage V3. The first voltage V1 is 0V, the second voltage V2 is greater than the first voltage V1, and the third voltage V3 is greater than the second voltage V2.

[0039] Figure 2 schematically shows the dimming sheet 11 in the first state. In the first state, the voltage between the transparent electrode layers 31 and 32 is controlled to a first voltage V1, and the liquid crystal composition exhibits a planar state. That is, most of the liquid crystal molecules 23 contained in the dimming layer 20 are aligned so that their long axes are aligned in a direction substantially parallel to the alignment layers 51 and 52 and the transparent electrode layers 31 and 32, and the helical axis of the liquid crystal composition having a helical structure extends in a direction substantially perpendicular to the alignment layers 51 and 52 and the transparent electrode layers 31 and 32.

[0040] When a liquid crystal composition that is a chiral nematic liquid crystal is in a planar state, the liquid crystal composition selectively reflects light in a certain wavelength range. In this embodiment, the liquid crystal composition selectively reflects visible light because the helical pitch P (μm), the ordinary refractive index no, and the extraordinary refractive index ne of the liquid crystal composition satisfy the following formula (1). 0.4≦P×(ne+2no) / 3≦0.8 (1)

[0041] As a result, in the first state, the dimming layer 20 selectively reflects visible light incident on the dimming layer 20 from the front or back surface of the dimming sheet 11. The helical pitch P, the ordinary refractive index no, and the extraordinary refractive index ne of the liquid crystal composition can each be adjusted by the type of liquid crystal molecule 23, the type of chiral agent, the amount of chiral agent added, etc.

[0042] In equation (1) above, "P × (ne + 2no) / 3" is the formula that defines the reflection wavelength of the liquid crystal composition. The derivation logic of this formula will be explained below. The reflection wavelength of a liquid crystal composition that is a chiral nematic liquid crystal is expressed as the product of the helical pitch P of the liquid crystal composition and the refractive index n. The simplest method for determining the refractive index n is to use the ordinary refractive index no. On the other hand, considering that liquid crystal molecules are birefringent, that in the first state of the dimming sheet 11 the helical axis of the liquid crystal composition can be assumed to be perpendicular to the dimming sheet 11, and that when light is incident on the dimming sheet 11 from outside, the direction of light propagation is approximately equal to the direction of the helical axis, it is also conceivable to use the average value of the ordinary refractive index no and the extraordinary refractive index ne as the refractive index n.

[0043] The inventors of this application compared the calculated reflection wavelength with the measured reflection wavelength of the dimming sheet 11 when using the ordinary refractive index no as the refractive index n, and when using the average value of the ordinary refractive index no and the extraordinary refractive index ne. As a result, it was confirmed that there is a discrepancy between the peak median in the measured values, that is, the median of the peak width in a peak with width, and the calculated reflection wavelength.

[0044] Here, the inventor focused on the possibility that there was a tilt in the helical axis. In this case, the effective refractive index of the liquid crystal composition with respect to incident light approaches the ordinary refractive index no rather than the average value of the ordinary refractive index no and the extraordinary refractive index ne. Therefore, the inventor derived the above formula "P × (ne + 2no) / 3" by using the weighted average of the ordinary refractive index no and the extraordinary refractive index ne as the refractive index n, weighting the ordinary refractive index no. The inventor then confirmed that the calculated value of the reflected wavelength using this formula matched the peak median value of the measured reflected wavelength of the dimming sheet 11. From this, it is suggested that the apparent helical pitch P changes due to the tilt of the helical axis, and that the variation in helical pitch P and this change in helical pitch P are factors that cause a width to be formed in the peak of the measured reflected wavelength.

[0045] As described above, the inventors of this application focused on the inclination of the helical axis in addition to the birefringence of liquid crystal molecules, and found that by using an equation weighted by the ordinary refractive index no, the reflection wavelength of a planar liquid crystal composition can be calculated more accurately.

[0046] By using a liquid crystal composition that satisfies the above formula (1) in the dimming layer 20, light of visible wavelengths is accurately reflected in the dimming sheet 11 in the first state. More specifically, from the visible light incident on the dimming layer 20, the circularly polarized component that rotates in the same direction as the twisting direction of the helical axis of the liquid crystal composition is reflected, while the other components are transmitted through the dimming layer 20.

[0047] Furthermore, in order to increase the reflectivity of visible light, it is preferable that in the first state, the liquid crystal molecules 23 are horizontally oriented in a region of 50% or more of the light-adjusting layer 20, that is, that the liquid crystal molecules 23 are oriented substantially parallel to the alignment layers 51, 52 and the transparent electrode layers 31, 32. It is also preferable that the proportion of the transparent polymer layer 21 in the light-adjusting layer 20 is less than 50%. For example, if the proportion of the horizontally oriented region near the surface of the light-adjusting layer 20 is 50% or more in an image observed with a polarizing microscope, it can be determined that the proportion of the horizontally oriented region in the entire light-adjusting layer 20 is 50% or more.

[0048] On the other hand, in order to accurately form a holding structure for the liquid crystal composition by the transparent polymer layer 21, the proportion of the transparent polymer layer 21 in the light-adjusting layer 20 is preferably 10% or more, and more preferably 20% or more. Furthermore, the proportion of the liquid crystal composition by the transparent polymer layer 21 is preferably 50% to 90%, and more preferably 60% to 80%. Therefore, in order to suitably form a holding structure for the liquid crystal composition while increasing the reflectance of visible light, in the first state, the region in which the liquid crystal molecules 23 are horizontally oriented is preferably 50% to 90%, and more preferably 60% to 80%, of the light-adjusting layer 20.

[0049] Figure 3 schematically shows the dimming sheet 11 in the second state. In the second state, the voltage between the transparent electrode layers 31 and 32 is controlled to a second voltage V2, and the liquid crystal composition exhibits a focal conic state. That is, the helical axis of the liquid crystal composition extends in a direction parallel to the alignment layers 51 and 52 and the transparent electrode layers 31 and 32, and in a direction different from the direction perpendicular to these layers.

[0050] When the liquid crystal composition is in a focal conic state, the angle between the direction of incidence of light onto the dimming sheet 11 and the long axis of the liquid crystal molecules 23 is not constant but dispersed within the dimming layer 20, so that light propagates while being reflected in various directions. In other words, in the second state, visible light incident on the dimming sheet 11 is scattered.

[0051] Figure 4 schematically shows the dimming sheet 11 in the third state. In the third state, the voltage between the transparent electrode layers 31 and 32 is controlled to a third voltage V3, and the liquid crystal composition exhibits a homeotropic state. That is, the helical structure of the liquid crystal composition unravels, and the liquid crystal molecules 23 are oriented along the electric field direction between the transparent electrode layers 31 and 32. In other words, the liquid crystal molecules 23 are aligned such that their long axis is aligned perpendicular to the orientation layers 51 and 52 and the transparent electrode layers 31 and 32.

[0052] Thus, the third voltage V3 is a voltage of a magnitude that orients the liquid crystal composition into a homeotropic state. The liquid crystal composition exhibits a homeotropic state when a voltage greater than or equal to a predetermined value corresponding to its composition is applied. The third voltage V3 is a voltage greater than or equal to the predetermined value mentioned above. The second voltage V2 applied in the second state described earlier is a voltage greater than 0V and less than the predetermined value mentioned above.

[0053] When the liquid crystal composition is in a homeotropic state, visible light is transmitted through the light-adjusting layer 20. In order to suppress the bending of the direction of propagation of visible light within the light-adjusting layer 20, it is preferable that the refractive index np of the polymer material constituting the transparent polymer layer 21 and the ordinary refractive index no of the liquid crystal composition are approximately the same. Specifically, it is preferable that the refractive index np of the polymer material and the ordinary refractive index no of the liquid crystal composition with respect to wavelengths in the visible region satisfy the following formula (2). The wavelength in the visible region can be, for example, the reflection wavelength of the liquid crystal composition determined by the above reflection wavelength specification formula "P × (ne + 2no) / 3". 0.98 ≤ np / no ≤ 1.02 ···(2)

[0054] Figure 5 shows a typical example of the relationship between the voltage between the transparent electrode layers 31 and 32 and the visible light transmittance in the dimming sheet 11 as the dimming sheet 11 changes from the first state through the second state to the third state. As shown in Figure 5, the visible light transmittance increases monotonically as the voltage increases from the first voltage V1 to the third voltage V3. Of these, the change in transmittance is gradual around the first voltage V1 and around the third voltage V3. On the other hand, the transmittance changes rapidly around the second voltage V2.

[0055] As described above, in the first state, where the voltage between the transparent electrode layers 31 and 32 is the first voltage V1, the reflection of visible light in the dimming layer 20 increases, and therefore the transmission of visible light decreases. On the other hand, in the third state, where the voltage between the transparent electrode layers 31 and 32 is the third voltage V3, the transmission of visible light increases. Then, in the second state, where the voltage between the transparent electrode layers 31 and 32 is the second voltage V2, scattering of visible light occurs, so the transmission of visible light is greater than in the first state but less than in the third state. As a result, the transmittance of visible light in the dimming sheet 11 changes according to the change in voltage between the transparent electrode layers 31 and 32, as shown in Figure 5.

[0056] Here, the change from the first state to the second state, and the change from the second state to the third state, are changes that are possible in only one direction. That is, when the dimming sheet 11 is in the first state, changing the voltage between the transparent electrode layers 31 and 32 from the first voltage V1 to the second voltage V2 causes the dimming sheet 11 to change from the first state to the second state. On the other hand, when the dimming sheet 11 is in the second state, changing the voltage between the transparent electrode layers 31 and 32 from the second voltage V2 to the first voltage V1 does not cause a change from the second state to the first state, and the liquid crystal composition maintains a focal conic state.

[0057] Similarly, when the dimming sheet 11 is in the second state, changing the voltage between the transparent electrode layers 31 and 32 to the third voltage V3 causes the dimming sheet 11 to change from the second state to the third state. On the other hand, when the dimming sheet 11 is in the third state, changing the voltage between the transparent electrode layers 31 and 32 from the third voltage V3 to the second voltage V2 does not cause a change from the third state to the second state, and the liquid crystal composition maintains a homeotropic state.

[0058] In contrast, the change from the first state to the third state is possible in both directions. That is, when the dimming sheet 11 is in the first state, changing the voltage between the transparent electrode layers 31 and 32 from the first voltage V1 to the third voltage V3 will change the dimming sheet 11 from the first state to the third state. Also, when the dimming sheet 11 is in the third state, changing the voltage between the transparent electrode layers 31 and 32 from the third voltage V3 to the first voltage V1 will change the dimming sheet 11 from the third state to the first state.

[0059] The second dimming sheet 12 has the same configuration as the first dimming sheet 11, except for the optical activity of the liquid crystal composition. That is, the optical activity of the liquid crystal composition of the dimming layer 20 of the first dimming sheet 11 is different from that of the liquid crystal composition of the dimming layer 20 of the second dimming sheet 12. For example, the liquid crystal composition of the first dimming sheet 11 is dextrorotatory, and the liquid crystal composition of the second dimming sheet 12 is levorotatory. By making the optical activity of the chiral agent contained in the liquid crystal composition different in the first dimming sheet 11 and the second dimming sheet 12, the optical activity of the liquid crystal composition can be made different.

[0060] It is preferable that the set value of the reflection wavelength of the first dimming sheet 11 and the set value of the reflection wavelength of the second dimming sheet 12 are the same. The set value of the reflection wavelength is a value calculated by the reflection wavelength specification formula "P × (ne + 2no) / 3". In other words, it is preferable that the peak wavelength of the reflected light of the first dimming sheet 11 in the first state matches the peak wavelength of the reflected light of the second dimming sheet 12 in the first state.

[0061] The control unit 60 may control the voltage applied to the first dimming sheet 11 and the voltage applied to the second dimming sheet 12 so that they are linked to each other, or it may control the dimming sheets 11 and 12 independently. The processes performed by the control unit 60 include setting each of the first dimming sheet 11 and the second dimming sheet 12 to a first state, setting each of the first dimming sheet 11 and the second dimming sheet 12 to a second state, and setting each of the first dimming sheet 11 and the second dimming sheet 12 to a third state.

[0062] [Examples of application] <Screen System> As a first application example of the dimming device 100, a configuration in which the dimming device 100 is applied to a screen system will be described.

[0063] The operation of the screen system including the dimming device 100 will be explained with reference to Figures 6 to 8. The screen system comprises a screen consisting of a sheet unit 10 and a control unit 60. Figure 6 shows the case when both the first dimming sheet 11 and the second dimming sheet 12 are in the first state, in other words, when the sheet unit 10 is in the first state. In this case, the screen system is used in a reflective projection system.

[0064] The projection device 70 and the observer Ob are positioned in one of the two spaces flanking the sheet unit 10. In the example shown in Figure 6, the projection device 70 and the observer Ob are positioned in the first space, which is the space facing the first dimmable sheet 11. The projection device 70 is, for example, a projector, which emits projection light PL1 toward the sheet unit 10 according to the data of the image to be projected. The projection device 70 may also be part of the screen system, and the drive of the projection device 70 may be controlled by the control unit 60.

[0065] When projected light PL1 is incident on the first dimming sheet 11, a portion of the projected light PL1, light RL1, is reflected by the first dimming sheet 11. The remaining light PL2 then passes through the first dimming sheet 11 and is incident on the second dimming sheet 12, where light RL2 is reflected. Light RL2 passes through the first dimming sheet 11 and is emitted into the first space where the observer Ob is located. Light RL1 and light RL2 are circularly polarized components that rotate in opposite directions. For example, when the liquid crystal composition of the first dimming sheet 11 is dextrorotatory and the liquid crystal composition of the second dimming sheet 12 is levorotatory, light RL1 is a right-circularly polarized component and light RL2 is a left-circularly polarized component. The observer Ob sees light RL1 and light RL2. As a result, the projected image is seen by the observer Ob.

[0066] In this way, the first dimming sheet 11 and the second dimming sheet 12 reflect different circularly polarized components from each other, resulting in most of the projected light PL1 being reflected by the sheet unit 10. Therefore, a high intensity of reflected light is obtained, which can increase the brightness of the image visible to the observer Ob. In addition, since leakage of a portion of the projected light PL1 into the space opposite the projection device 70 and the observer Ob from the sheet unit 10 is suppressed, unwanted light leakage into the space behind the sheet unit 10 can be reduced.

[0067] For example, it is possible to use a dimmable sheet that can switch between a scattering state and a transparent state, as in conventional designs, as a screen for a reflective projection system by laminating a reflective layer onto it. However, in order to make the scenery behind the dimmable sheet visible in the transparent state, it is necessary to use a film with a certain degree of light transmittance, such as a half-mirror film, as the reflective layer, and as a result, there are limits to how much the reflectivity of the reflective layer can be increased. Therefore, there are limits to how much the intensity of the reflected light can be increased, that is, how much the brightness of the image can be increased, and also, because the reflective layer is light transmittance, it is difficult to suppress light leakage into the space behind the screen.

[0068] In contrast, if the sheet unit 10 of this embodiment is used as a screen, as described above, most of the projected light is reflected by the two dimming sheets 11 and 12 in the first state, making it possible to increase the brightness of the image and also to suppress light leakage into the space behind the screen.

[0069] Furthermore, images can also be projected from the side where the second dimming sheet 12 is located. That is, the projection device 70 and the observer Ob are positioned in the second space, which is the space facing the second dimming sheet 12, and the observer Ob can see the image projected from the projection device 70 onto the sheet unit 10. It is also possible to project different images simultaneously in the first space and the second space.

[0070] For example, the screen system may include projection devices 70 located in a first space and a second space, respectively. In the first space, the first projection device 70 projects a first image onto a first dimming sheet 11, and in the second space, the second projection device 70 projects a second image onto a second dimming sheet 12. The first image and the second image can be different images, and these images may be projected simultaneously. With this configuration, images can be projected in two spaces using a single screen, or sheet unit 10, thus simplifying the equipment and enabling efficient use of space.

[0071] Figure 7 shows the case when both the first dimming sheet 11 and the second dimming sheet 12 are in the second state, in other words, when the sheet unit 10 is in the second state. In this case, when ambient light NL, which is the light from the lighting or sunlight, is incident on the dimming sheets 11 and 12, light scattering occurs, and scattered light SL is emitted from the dimming sheets 11 and 12. The observer Ob sees the scattered light SL. As a result, the dimming sheets 11 and 12 appear blurred, and the scenery behind the sheet unit 10 appears unclear. In this case, it is also suppressed that the observer Ob and their surroundings can be seen from the outside through the sheet unit 10.

[0072] Furthermore, in order to lower the transparency of each dimming sheet 11, 12 in the second state, that is, to increase the haze of the dimming sheets 11, 12, it is preferable to use a liquid crystal composition with a large refractive index anisotropy Δn. However, liquid crystal molecules with a large refractive index anisotropy Δn, such as translucent liquid crystal molecules, are not highly versatile, and when such liquid crystal molecules are used, the reliability of the dimming layer 20 tends to be low. In contrast, in the sheet unit 10 of this embodiment, since the first dimming sheet 11 and the second dimming sheet 12 overlap, it is possible to lower the transparency of the sheet unit 10 even when the haze of each dimming sheet 11, 12 is low.

[0073] Therefore, by using a liquid crystal composition with low refractive index anisotropy Δn, specifically a liquid crystal composition containing liquid crystal molecules with refractive index anisotropy Δn of 0.16 or less, it is possible to keep the transparency of the sheet unit 10 low in the second state while improving the reliability of the dimming sheets 11 and 12.

[0074] Figure 8 shows the case when both the first dimming sheet 11 and the second dimming sheet 12 are in the third state, in other words, when the sheet unit 10 is in the third state. In this case, ambient light NL, which is the light from the lighting or sunlight, passes through the dimming sheets 11 and 12. Therefore, the dimming sheets 11 and 12 are transparent, and the observer Ob can see the scenery behind the sheet unit 10.

[0075] As described above, when a reflective layer is superimposed on a conventional dimmable sheet that can switch between a scattering state and a transparent state and used as a screen, the light transmittance of the dimmable sheet in the transparent state is lower compared to when a reflective layer is not provided. In contrast, with the sheet unit 10 of this embodiment, a first state capable of reflecting visible light can be realized without using a reflective layer, thus enabling high light transmittance in the transparent third state.

[0076] As described above, according to the first application example, by utilizing the selective reflection of chiral nematic liquid crystal, the sheet unit 10 consisting of dimming sheets 11 and 12 can be used as a screen in a reflective projection system. By switching between the first, second, and third states, the sheet unit 10 can be switched between a state on which an image can be projected, a cloudy state, and a transparent state. Therefore, the degree of freedom regarding the placement of the sheet unit 10 and the use of the space on which the sheet unit 10 is placed is increased.

[0077] Furthermore, even if the applied voltage is reduced to 0V after switching the sheet unit 10 to the second state, the visible light scattering function is maintained in the same way as in the second state. Therefore, it is possible to reduce power consumption while maintaining a low transparency state of the sheet unit 10.

[0078] <Dimmable window> As a second application example of the dimming device 100, we will describe an application of the dimming device 100 to a dimmable window.

[0079] Referring to Figure 9, the operation of the dimmable window including the dimming device 100 will be described. The dimmable window comprises a window to which the sheet unit 10 is attached and a control unit 60. Figure 9 shows the case when both the first dimmable sheet 11 and the second dimmable sheet 12 are in the first state, in other words, when the sheet unit 10 is in the first state. In the example shown in Figure 9, the observer Ob is positioned in the first space, which is the space facing the first dimmable sheet 11.

[0080] When ambient light NL1, which is illumination light or sunlight, is incident on the second dimming sheet 12 from the second space opposite to the first space relative to the sheet unit 10, a portion of the ambient light NL1, RL1, is reflected by the second dimming sheet 12. The remaining light NL2 then passes through the second dimming sheet 12 and is incident on the first dimming sheet 11, where light RL2 is reflected. Light RL1 and light RL2 are circularly polarized components that rotate in opposite directions. For example, when the liquid crystal composition of the second dimming sheet 12 is levorotatory and the liquid crystal composition of the first dimming sheet 11 is dextrorotatory, light RL1 is a left-circularly polarized component and light RL2 is a right-circularly polarized component.

[0081] Thus, the first dimming sheet 11 and the second dimming sheet 12 reflect different circularly polarized light components from each other, resulting in most of the ambient light NL1 being reflected by the sheet unit 10. Therefore, the incidence of ambient light into the first space where the observer Ob is located is suppressed. In other words, light shielding by the sheet unit 10 is possible.

[0082] When both of the two dimming sheets 11 and 12 are in the second state, and when both of the two dimming sheets 11 and 12 are in the third state, the situation is the same as in the first application example described with reference to Figures 7 and 8.

[0083] As described above, according to the second application example, by switching between the first, second, and third states, the sheet unit 10 can be switched between a light-shielding state, a cloudy state, and a transparent state. Therefore, it becomes possible to switch between a wider variety of effects that the sheet unit 10 has on the space.

[0084] Furthermore, similar to the first application example, even if the applied voltage is reduced to 0V after switching the sheet unit 10 to the second state, the visible light scattering function is maintained in the same way as in the second state. Therefore, it is possible to reduce power consumption while maintaining a low transparency state of the sheet unit 10.

[0085] Furthermore, in both the first and second application examples, the control unit 60 may separately control the voltage applied to the first dimming sheet 11 and the second dimming sheet 12, and control the state of each dimming sheet 11 and 12 so that they are in different states among the first, second, and third states. This makes it possible to switch the degree of reflection, transmission, and scattering of visible light in the sheet unit 10 more precisely.

[0086] According to the above embodiment, the following effects can be obtained. (1) By switching the voltage applied to the sheet unit 10, the sheet unit 10 can be switched between a first state in which it reflects visible light, a second state in which it scatters visible light, and a third state in which it transmits visible light. This allows for switching of optical properties that are different from switching between a transmission state and a scattering state, so the dimmable sheet can be used in new applications such as a screen system used in a reflective projection system or a dimmable window that can block light.

[0087] (2) Since the first state, which reflects visible light, can be realized without using a reflective layer such as a half-mirror film, high light transmittance can be obtained in the third state. (3) The sheet unit 10 comprises two dimming sheets 11 and 12 with different optical rotations, and these dimming sheets 11 and 12 are arranged to overlap in the thickness direction. As a result, when the two dimming sheets 11 and 12 are in the first state, different circularly polarized components are reflected from each other, so more components of the light irradiated onto the sheet unit 10 are reflected. Therefore, the intensity of the reflected light is increased, and the transmission of light through the sheet unit 10 can be further suppressed. As a result, if it is a screen system, it is possible to project a brighter image and to suppress light leakage into the space behind the screen. If it is a dimming window, the light-shielding ability can be improved.

[0088] (4) The helical pitch P, ordinary refractive index no, and extraordinary refractive index ne of the liquid crystal composition in the dimming sheets 11 and 12 satisfy the following formula (1). This ensures that the reflection wavelength of the liquid crystal composition, which is a chiral nematic liquid crystal, is accurately set in the visible region. 0.4≦P×(ne+2no) / 3≦0.8 (1)

[0089] (5) In the first state of the dimming sheets 11 and 12, the proportion of the region in the dimming layer 20 in which the liquid crystal molecules 23 contained in the liquid crystal composition are horizontally oriented is 50% or more. This provides good reflectivity for visible light.

[0090] (6) The proportion of the transparent polymer layer 21 in the light-adjusting layer 20 is less than 50%. This ensures a sufficient proportion of the liquid crystal composition in the light-adjusting layer 20, and a good reflectivity of visible light is obtained in the first state.

[0091] (7) The refractive index np of the polymer material constituting the transparent polymer layer 21 and the ordinary refractive index no of the liquid crystal composition satisfy the following equation (2). As a result, in the third state, visible light can more easily travel in a straight line through the dimming layer 20, thereby increasing the transmittance of visible light. 0.98 ≤ np / no ≤ 1.02 ···(2)

[0092] (8) The dimming sheets 11 and 12 are equipped with alignment layers 51 and 52. This makes it possible to increase the proportion of liquid crystal molecules 23 that are horizontally aligned in the first state. Therefore, the reflectance of visible light in the first state is increased.

[0093] (9) In the configuration in which the dimming device 100 is applied to a screen system, the sheet unit 10 can be switched between a state on which an image can be projected in a reflective projection system, a cloudy state, and a transparent state. In this way, the sheet unit 10 can be used as a screen for a reflective projection system.

[0094] (10) The screen system comprises a first projection device that irradiates light toward a first dimming sheet 11, and a second projection device that irradiates light toward a second dimming sheet 12 from the opposite side of the sheet unit 10, which is the screen, from the first projection device. With this configuration, it is possible to project images in each of the two spaces flanking the sheet unit 10 using a single screen, which is the sheet unit 10. Therefore, it is possible to simplify the equipment while making efficient use of space.

[0095] (11) In the configuration in which the dimming device 100 is applied to a dimmable window, the sheet unit 10 can be switched between a light-blocking state, a cloudy state, and a transparent state. Thus, a dimmable window that can be switched between a light-blocking state and other states can be realized.

[0096] [Examples] The dimming device and dimming sheet described above will be explained using specific examples. (Manufacturing of the seat unit) A first photochromic sheet was formed comprising a photochromic layer, a pair of transparent electrode layers, a pair of transparent support layers, and a pair of orientation layers. The material of the transparent electrode layers was indium tin oxide, the material of the transparent support layers was polyethylene terephthalate, and the material of the orientation layers was polyimide. The photochromic layer was of a polymer network type, and was formed such that each parameter was as follows.

[0097] • Dielectric anisotropy Δε of the liquid crystal composition: 10.9 • Refractive index of liquid crystal composition: No. 1.51 • Abnormal refractive index ne of the liquid crystal composition: 1.68 • Refractive index np: 1.50 of the polymer material constituting the transparent polymer layer • Helical pitch P of liquid crystal composition: 0.33 μm • Reflection wavelength setting (P × (ne + 2no) / 3): 0.52 μm • Percentage of transparent polymer layer in the photochromic layer: 12.6% • Optical activity of chiral agents: dextrorotatory The second photochromic sheet was formed using the same materials as the first photochromic sheet, except that a levorotatory chiral agent was used. In other words, the parameters of the photochromic layer in the second photochromic sheet were the same as those in the first photochromic sheet, except for the optical activity of the chiral agent.

[0098] (Reflection characteristics analysis) For the two dimmable sheets in the example, the wavelength range and reflectance of the reflected light were measured when the applied voltage was 0V. When the applied voltage is 0V, the dimmable sheet is in the first state. The measurement results are shown in Figure 10.

[0099] As shown in Figure 10, when the applied voltage is 0V, a reflection with a peak around 520nm is obtained in both of the dimming sheets. The peak wavelength of the reflected light roughly coincides with the set value of the reflection wavelength described above. The full width at half maximum of the peak is 70nm to 80nm, and the reflectance near the peak wavelength is approximately 50%.

[0100] Based on the above, it has been confirmed that the dimming sheet of the embodiment enables selective reflection of visible light. Therefore, this dimming sheet can be used as a screen for a reflective projection system, or it can be used to achieve a light-blocking state in a dimming window.

[0101] [Differentiation] The above embodiment can be implemented with the following modifications. The following modifications may be implemented in combination.

[0102] The dimming sheet does not necessarily have alignment layers 51 and 52. If alignment layers 51 and 52 are not provided, the proportion of liquid crystal molecules 23 that are horizontally aligned in the first state will be smaller compared to the above embodiment. On the other hand, if liquid crystal molecules 23 are horizontally aligned in more than 50% of the area of ​​the dimming layer 20, a good reflectivity for visible light can be obtained. Even without alignment layers 51 and 52, if chiral nematic liquid crystal is used, liquid crystal molecules 23 can be made horizontally aligned in more than 50% of the area when no voltage is applied. If the formation of alignment layers is unnecessary, the manufacturing process of the dimming sheet can be simplified and the cost of manufacturing can be reduced.

[0103] The peak wavelength of the reflected light from the first dimming sheet 11 in the first state may be different from the peak wavelength of the reflected light from the second dimming sheet 12 in the first state. If the peak wavelengths of the reflected light from the two dimming sheets 11 and 12 are different, light in the wavelength range near each peak wavelength will be reflected, making it possible to reflect visible light over a wide wavelength range. This configuration can be adopted when expanding the reflective wavelength range is desired rather than increasing the intensity of the reflected light or suppressing the transmission of light in the sheet unit 10. If the peak wavelengths of the reflected light from the two dimming sheets 11 and 12 in the first state are different from each other, the optical rotation of the liquid crystal compositions of these dimming sheets 11 and 12 may be the same.

[0104] The sheet unit 10 may have only one dimming sheet. That is, the sheet unit 10 may have a first dimming sheet 11 but not a second dimming sheet 12. In this case, when the dimming sheet 11 is in the first state, a portion of the incident light is reflected by the sheet unit 10. Even with such a configuration, it is possible to project images using a reflective projection system and to block light in a dimming window. This configuration can be adopted when it is desirable to simplify the structure of the sheet unit 10 rather than increasing the intensity of reflected light or suppressing light transmission through the sheet unit 10.

[0105] The first and second application examples may be used in combination. That is, the user may use the sheet unit 10 in the first state as a screen or for light shielding depending on the situation. Also, the sheet unit 10 in the second state may be used as a screen for a transmissive projection system. That is, projection light is shone onto the sheet unit 10 from the opposite side from the observer. The scattered light emitted from the sheet unit 10 is then visible to the observer, and the image is visible to the observer.

[0106] The dimming device 100 controls the sheet unit 10 to either the first state or the third state, and does not need to switch the sheet unit 10 to the second state. If it is possible to switch between the first state and the third state, it is possible to switch the sheet unit 10 between a state in which it reflects visible light and a state in which it transmits visible light. In other words, in a screen system, it is possible to switch between a state in which an image can be projected onto the sheet unit 10 and a state in which the sheet unit 10 is transparent. Also, in a dimming window, it is possible to switch between a state in which the sheet unit 10 blocks light and a state in which the sheet unit 10 is transparent. Therefore, dimming sheets can be used for different purposes than conventional dimming sheets that can switch between a transmittance state and a scattering state. [Explanation of Symbols]

[0107] 10...Seat unit 11, 12… Dimmable sheets 20…Dimming layer 21...Transparent polymer layer 22...Void 23…Liquid crystal molecules 31,32...Transparent electrode layer 41,42...Transparent support layer 51, 52… Orientation layers 60... Control Unit 70...projection device 100... Dimming device 110...Transparent plate

Claims

1. A screen system including a dimming sheet and a dimming device comprising a control unit for controlling the application of voltage to the dimming sheet, The aforementioned dimming sheet is First transparent electrode layer, The second transparent electrode layer, A light-adjusting layer located between the first transparent electrode layer and the second transparent electrode layer, comprising a transparent polymer layer separating a plurality of voids, and a liquid crystal composition having positive dielectric anisotropy and held in the voids, A first orientation layer sandwiched between the first transparent electrode layer and the photochromic layer, The device comprises a second orientation layer sandwiched between the second transparent electrode layer and the photochromic layer, Each of the aforementioned first orientation layer and the aforementioned second orientation layer is a horizontally oriented film, The processing performed by the control unit includes: By controlling the voltage between the first transparent electrode layer and the second transparent electrode layer to a first voltage, the dimming sheet is brought into a first state that reflects visible light. This includes controlling the voltage between the first transparent electrode layer and the second transparent electrode layer to a third voltage greater than the first voltage, thereby putting the dimming sheet into a third state that transmits visible light. In the first state described above, the helical axis of the liquid crystal composition having a helical structure is inclined with respect to a direction perpendicular to the dimming sheet, The helical pitch P (μm), ordinary refractive index no, and extraordinary refractive index ne of the liquid crystal composition in the dimming sheet satisfy the following formula (1-1), and the peak median value λm of the reflection wavelength of the dimming sheet in the first state satisfies the following formula (1-2). 0.4≦P×(ne+2no) / 3≦0.8 (1-1) λm=P×(ne+2no) / 3...(1-2) The dimming device comprises two dimming sheets, a first dimming sheet and a second dimming sheet. The optical activity of the liquid crystal composition contained in the first dimming sheet and the optical activity of the liquid crystal composition contained in the second dimming sheet are different from each other. The first dimming sheet and the second dimming sheet are arranged so as to overlap in the thickness direction. The processing performed by the control unit includes setting each of the first dimming sheet and the second dimming sheet to the first state. The aforementioned screen system A screen comprising the first dimming sheet and the second dimming sheet, A first projection device that irradiates light toward the first dimming sheet, The system includes a second projection device that irradiates light onto the second dimming sheet from the opposite side of the screen from the first projection device. Screen system.

2. The processing performed by the control unit further includes: This includes controlling the voltage between the first transparent electrode layer and the second transparent electrode layer to a second voltage that is greater than the first voltage and less than the third voltage, thereby putting the dimming sheet into a second state that scatters visible light. The screen system according to claim 1.

3. In the first state of the dimming sheet, the proportion of the region in the dimming layer where the liquid crystal molecules contained in the liquid crystal composition are horizontally oriented is 50% or more. The screen system according to claim 1 or 2.

4. The proportion of the transparent polymer layer in the light-adjusting layer of the light-adjusting sheet is less than 50%. The screen system according to any one of claims 1 to 3.

5. The refractive index np of the polymer material constituting the transparent polymer layer in the dimming sheet and the ordinary refractive index no of the liquid crystal composition satisfy the following formula (2). 0.98 ≤ np / no ≤ 1.02 ... (2) The screen system according to any one of claims 1 to 4.

6. The processing performed by the control unit further includes: This includes, at least one of the following: putting each of the first and second dimming sheets into a second state that scatters visible light by controlling the voltage between the first transparent electrode layer and the second transparent electrode layer to a second voltage that is greater than the first voltage and less than the third voltage; and putting each of the first and second dimming sheets into the third state. The screen system according to any one of claims 1 to 5.

Images