Dimming device

Abstract

To provide a dimmer with which it is possible to suppress deviation from occurring to recognition of an object put through a dimming sheet.SOLUTION: A dimmer 10 comprises: a dimming sheet 10A being provided with a first transparent electrode layer 12A, a second transparent electrode layer 12B and a dimming layer 11, the dimming layer 11 including a liquid crystal molecule 11BL, and located between the first and second transparent electrode layers 12A, 12B; and a drive circuit 10D for changing voltage applied to between the first and second transparent electrode layers 12A, 12B, and switching a state of the dimming sheet 10A between a first state that is an opaque state and a second state that is a transparent state, as an orientation of the liquid crystal molecule 11BL is switched in correspondence to a value of the applied voltage. The drive circuit 10D applies such voltage that a value of clarity of the dimming sheet 10A is 83% or less and places the dimming sheet 10A into the first state, and applies such voltage that a haze value of the dimming sheet 10A conforming to JIS K 7136 is 15% or less and places the dimming sheet 10A into the second state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a dimming device. [Background technology]

[0002] The dimming device comprises a dimming sheet and a drive circuit. The dimming sheet comprises a dimming layer and a pair of transparent electrodes sandwiching the dimming layer in the thickness direction of the dimming layer. The dimming layer comprises, for example, a polymer network containing a plurality of pores and a liquid crystal composition containing a plurality of liquid crystal molecules filling the pores. The drive circuit applies a voltage between the pair of transparent electrodes. The orientation state of the liquid crystal molecules changes according to the potential difference between the pair of transparent electrodes, thereby changing the transmittance of the dimming sheet. The transmittance of the dimming sheet is evaluated using haze, which is the ratio of diffuse transmittance to total light transmittance (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-31870 [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, the haze value of a dimmable sheet changes in response to changes in the applied voltage within a predetermined range of the applied voltage, and remains almost constant with respect to changes in the applied voltage outside that predetermined range. On the other hand, the degree of scattering of a dimmable sheet indicates a cloudy appearance when driven transparently, and a translucent appearance when opaque. The haze value is almost constant, but it also changes with respect to changes in the applied voltage outside the predetermined range mentioned above. As a result, among dimmable sheets with equal haze values, discrepancies arise in the degree of scattering, and consequently, in the recognition of objects seen through the dimmable sheet.

[0005] The present invention aims to provide a dimming device that can suppress discrepancies in the recognition of objects seen through a dimming sheet. [Means for solving the problem]

[0006] A dimming device for solving the above problems comprises a dimming sheet having a first transparent electrode layer, a second transparent electrode layer, and a dimming layer, wherein the dimming layer contains liquid crystal molecules and is located between the first transparent electrode layer and the second transparent electrode layer; and a drive circuit configured to change the voltage applied between the first transparent electrode layer and the second transparent electrode layer, thereby switching the state of the dimming sheet between a first state, which is opaque, and a second state, which is transparent, by switching the orientation of the liquid crystal molecules according to the value of the voltage. The drive circuit applies a voltage such that the clarity value of the dimming sheet becomes 83% or less to set the dimming sheet to the first state, and applies a voltage such that the haze value of the dimming sheet conforming to JIS K 7136:2000 becomes 15% or less to set the dimming sheet to the second state. Clarity is the amount of straight-traveling light that travels in a straight line along the direction of propagation of parallel light incident on the dimming sheet, along the normal direction of the plane on which the dimming sheet extends, within the light transmitted through the dimming sheet, defined as the amount of light L. C The amount of light from narrow-angle scattered light, where the angle with respect to the direction of propagation of the parallel light is within ±2.5°, is defined as the amount of light L. R In this case, it is calculated by the following formula (1). 100×(L C -L R ) / (L C +L R ) … Formula (1)

[0007] As described above, the haze value of the dimming sheet changes in response to changes in the applied voltage within a predetermined range of the applied voltage, and remains almost constant with respect to changes in the applied voltage outside that predetermined range. On the other hand, the degree of scattering of the dimming sheet also changes with respect to changes in the applied voltage outside that predetermined range, and the clarity value, which depends on narrow-angle scattering, also changes with respect to changes in the applied voltage outside that predetermined range.

[0008] In this respect, with the above configuration, in the first state of the dimmable sheet, the clarity value, which depends on narrow-angle scattering, is 83% or less, so the degree of scattering in the dimmable sheet shows sufficient opacity for recognizing objects that pass through the dimmable sheet. Then, in the second state of the dimmable sheet, the haze value, which depends on wide-angle scattering where the angle with respect to the direction of propagation of parallel light is greater than ±2.5°, is 15% or less, so the degree of scattering in the dimmable sheet shows sufficient transparency for recognizing objects that pass through the dimmable sheet. Therefore, compared to a configuration in which the degree of scattering is determined by a single parameter such as haze, it is possible to suppress discrepancies in the recognition of objects that pass through the dimmable sheet. For example, it is possible to suppress discrepancies between dimmable sheets in the results of evaluating the transmittance of the dimmable sheet during manufacturing, or in the results of driving the dimmable sheet to change its transmittance in steps.

[0009] In the above-described dimming device, the drive circuit drives the dimming sheet in a first mode, in which the absolute value of the change in the clarity value per unit voltage is greater than the absolute value of the change in the haze value per unit voltage, and the dimming sheet is in the first state, and a voltage corresponding to each set value of the clarity may be selectively applied.

[0010] According to the above configuration, when the dimming sheet is driven in the first mode, the voltage applied between the first transparent electrode layer and the second transparent electrode layer corresponds to the clarity setting value. In other words, in a dimming sheet driven in the first mode, each clarity setting value that governs the change in the degree of scattering is obtained by applying a voltage. As a result, it becomes possible to select a preset degree of scattering without causing a discrepancy in the recognition of objects seen through the dimming sheet.

[0011] In the above-described dimming device, the drive circuit drives the dimming sheet in a second mode, in which the absolute value of the change in the haze value per unit voltage is greater than or equal to the absolute value of the change in the clarity value per unit voltage, and the dimming sheet is in the second state, and the drive circuit may selectively apply voltages corresponding to each set value of the haze, which is set within the range of the haze value that indicates the dimming sheet is in the second state.

[0012] According to the above configuration, when the dimming sheet is driven in the second mode, the voltage applied between the first transparent electrode layer and the second transparent electrode layer corresponds to the set value of the haze. In other words, in a dimming sheet driven in the second mode, each set value of the haze that governs the change in the degree of scattering is obtained by applying a voltage. As a result, it becomes possible to select a preset degree of scattering without causing a discrepancy in the recognition of objects seen through the dimming sheet.

[0013] In the above-described dimming device, the drive circuit may apply a voltage in a range where the absolute value |ΔH / ΔC| of the ratio of the change in the haze value per unit voltage of 5V to the change in the clarity value ΔC per unit voltage of 5V is 80 or more, either continuously or intermittently, to bring the dimming sheet to the second state. With this configuration, it is possible to enhance the effectiveness of obtaining the above-described discrepancy suppression effect when the dimming sheet is transparent.

[0014] In the above-described dimming device, the drive circuit may set the dimming sheet to the first state by applying a voltage such that the absolute value |ΔH / ΔC| of the ratio of the change in the haze value per unit voltage of 1V to the change in the clarity value ΔC per unit voltage of 1V is 0.1 or less. With this configuration, it is possible to enhance the effectiveness of obtaining the above-described discrepancy suppression effect when the dimming sheet is opaque. [Effects of the Invention]

[0015] According to the present invention, it is possible to suppress the occurrence of deviation in the recognition of an object through a dimming sheet.

Brief Description of the Drawings

[0016] [Figure 1] Cross-sectional view showing a state where no driving voltage is applied to the dimming layer in the first configuration of the dimming device. [Figure 2] Cross-sectional view showing a state where a driving voltage is applied to the dimming layer in the first configuration of the dimming device. [Figure 3] Cross-sectional view showing a state where no driving voltage is applied to the dimming layer in the second configuration of the dimming device. [Figure 4] Cross-sectional view showing a state where a driving voltage is applied to the dimming layer in the second configuration of the dimming device. [Figure 5] Diagram schematically showing the configuration of the clarity measurement device together with the dimming device to be measured. [Figure 6] Graph showing the relationship between haze and clarity in the dimming sheet.

Modes for Carrying Out the Invention

[0017] Referring to FIGS. 1 to 6, an embodiment of the dimming device will be described. Hereinafter, the configuration of the dimming device, the method for measuring clarity, and examples will be described in order. In this embodiment, an object existing through the dimming sheet, for example, an object to be concealed by the dimming sheet, is generically referred to as a target. The target includes, for example, a person, a device, and a still life.

[0018] [Configuration of the Dimming Device] Referring to FIGS. 1 to 4, the configuration of the dimming device will be described. The dimming device in this embodiment includes the first configuration and the second configuration described below.

[0019] [First Configuration] Referring to FIGS. 1 and 2, the first configuration of the dimming device will be described. Figure 1 shows the first configuration of the dimming device in which no driving voltage is applied to the dimming sheet. The driving voltage is a voltage used to change the orientation of the liquid crystal molecules contained in the dimming layer of the dimming sheet. In contrast, Figure 2 shows the first configuration of the dimming device in which an example of a driving voltage is applied, which is a saturation voltage at which the orientation of the liquid crystal molecules does not change easily as the driving voltage increases. In the first configuration, as the magnitude of the driving voltage applied to the dimming sheet increases, the orientation of the liquid crystal molecules changes from the orientation shown in Figure 1 to the orientation shown in Figure 2.

[0020] As shown in Figure 1, the dimming device 10 includes a dimming sheet 10A. The dimming sheet 10A comprises a dimming layer 11, a pair of transparent electrode layers 12, and a pair of transparent substrates 13. In this embodiment, the dimming layer 11 comprises a polymer network 11A and a liquid crystal composition 11B. The polymer network 11A includes a plurality of pores 11D. Each pore 11D is a void formed within the polymer network 11A. The pores 11D may be isolated spaces by the polymer network 11A or spaces connected to other pores 11D. The liquid crystal composition 11B fills the pores 11D and includes a plurality of liquid crystal molecules 11BL. The transmittance of the dimming layer 11 changes as the orientation of the liquid crystal molecules 11BL contained in the dimming layer 11 changes.

[0021] The pair of transparent electrode layers 12 consists of a first transparent electrode layer 12A and a second transparent electrode layer 12B. The light-adjusting layer 11 is located between the first transparent electrode layer 12A and the second transparent electrode layer 12B, with the pair of transparent electrode layers 12 sandwiching the light-adjusting layer 11 in the thickness direction. Each transparent electrode layer 12 is transparent to visible light. The material forming each transparent electrode layer 12 may be, for example, a transparent conductive oxide (TCO) and a conductive polymer. The pair of transparent substrates 13 sandwich the pair of transparent electrode layers 12 in the thickness direction of the light-adjusting layer 11. Each transparent substrate 13 is transparent to visible light. The material forming each transparent substrate 13 may be, for example, glass and a synthetic resin.

[0022] The dimming device 10 further includes a drive circuit 10D connected to the dimming sheet 10A. The drive circuit 10D applies a drive voltage between the first transparent electrode layer 12A and the second transparent electrode layer 12B. By changing the magnitude of the drive voltage applied to the transparent electrode layer 12, the orientation of the liquid crystal molecules contained in the dimming layer 11 changes, which in turn changes the haze value and clarity value of the dimming sheet 10A.

[0023] The drive circuit 10D changes the voltage applied between the first transparent electrode layer 12A and the second transparent electrode layer 12B, and switches the state of the dimming sheet 10A between the first state and the second state by switching the orientation of the liquid crystal molecules 11BL in response to the change in voltage. In the dimming sheet 10A, the first state is opaque, and the second state is transparent.

[0024] The drive circuit 10D applies a voltage such that the clarity value of the dimming sheet 10A becomes 83% or less, putting the dimming sheet 10A into a first state. The first state is opaque, for example, the most opaque state of the dimming sheet 10A. The drive circuit 10D applies a voltage such that the haze value of the dimming sheet 10A becomes 15% or less, putting the dimming sheet 10A into a second state. The second state is transparent, for example, the most transparent state of the dimming sheet 10A. Note that haze is a parameter conforming to JIS K 7136:2000. In contrast, clarity is a parameter defined by equation (1) described later.

[0025] The drive circuit 10D is configured to allow selection between a first mode and a second mode of operation. The selection of the drive mode in the drive circuit 10D is performed, for example, according to the input of an external control signal.

[0026] In the first mode, the absolute value of the change in clarity value per unit voltage is greater than the absolute value of the change in haze value per unit voltage. When the drive circuit 10D is driven in the first mode, the dimming sheet 10A includes a first state and other states. The drive circuit 10D uses the absolute value of the ratio of the change in haze value per unit voltage to the change in clarity value per unit voltage as an index parameter, and drives the dimming sheet 10A so that the index parameter is within a predetermined range. That is, the drive circuit 10D selectively applies multiple voltages at different timings such that the index parameter is less than 1, thereby putting the dimming sheet into the first state or any other state that satisfies the index parameter being less than 1. When the drive circuit 10D is driven in the first mode, the drive circuit 10D selectively applies voltages corresponding to each clarity setting. When the unit voltage is 1V, it is preferable that the drive circuit 10D applies a voltage such that the absolute value of the ratio of the change in the haze value per unit voltage to the change in the clarity value per unit voltage is 0.1 or less, thereby putting the dimming sheet 10A into a first state.

[0027] In the second mode, the absolute value of the change in the haze value per unit voltage is greater than or equal to the absolute value of the change in the clarity value per unit voltage. When the drive circuit 10D is driven in the second mode, the dimming sheet 10A includes the second state and other states. The drive circuit 10D selectively applies a plurality of voltages at different timings such that the index parameter is 1 or greater, thereby putting the dimming sheet into the second state or other states where the index parameter is 1 or greater. When the drive circuit 10D is driven in the second mode, the drive circuit 10D selectively applies voltages corresponding to each set value of the haze. When the unit voltage is 5V, it is preferable for the drive circuit 10D to put the dimming sheet 10A into the second state by applying voltages in a range where the absolute value of the ratio of the change in the haze value per unit voltage to the change in the clarity value per unit voltage is continuously or intermittently 80 or greater.

[0028] The change in haze ΔH when the drive voltage applied to the dimming sheet 10A is changed from drive voltage V1 to drive voltage V2 is calculated by the following formula (2). Here, the haze value when drive voltage V1 is applied is haze H1, and the haze value when drive voltage V2 is applied is haze H2. Also, drive voltage V2 is greater than drive voltage V1, and the value obtained by subtracting drive voltage V1 from drive voltage V2 is the unit voltage (V2-V1). ΔH=(H2-H1) / (V2-V1)...Equation (2)

[0029] Furthermore, the change in clarity ΔC when the drive voltage applied to the dimming sheet 10A is changed from drive voltage V1 to drive voltage V2 is calculated by the following equation (3). Here, the clarity value when drive voltage V1 is applied is clarity C1, and the clarity value when drive voltage V2 is applied is clarity C2. Also, drive voltage V2 is greater than drive voltage V1. ΔC=(C2-C1) / (V2-V1)...Equation (3)

[0030] The absolute value of the change in haze calculated by equation (2) above is |ΔH|, and the absolute value of the change in clarity calculated by equation (3) above is |ΔC|. The absolute value of the ratio of the change in haze value per unit voltage to the change in clarity value per unit voltage is |ΔH / ΔC|.

[0031] The first state described above includes the state defined by the following equation (4), and the second state includes the state defined by the following equation (5). |ΔH|<|ΔC| … Equation (4) |ΔH|≧|ΔC| … Equation (5)

[0032] The dimming sheet 10A has a first characteristic and a second characteristic. The first characteristic and the second characteristic appear alternately depending on the orientation of the liquid crystal molecules 11BL in the dimming layer 11. In the first characteristic, the absolute value of the change in clarity value per unit voltage is greater than the absolute value of the change in haze value per unit voltage. In the second characteristic, the absolute value of the change in haze value per unit voltage is greater than or equal to the absolute value of the change in clarity value per unit voltage. The first characteristic is defined by the above equation (4), and the second characteristic is defined by the above equation (5).

[0033] The drive circuit 10D causes the photochromic sheet 10A to exhibit a first characteristic by applying a drive voltage corresponding to a predetermined value for clarity between the transparent electrode layers 12. Furthermore, the drive circuit 10D causes the photochromic sheet 10A to exhibit a second characteristic by applying a drive voltage corresponding to a predetermined value for haze between the transparent electrode layers 12. In this way, when the first characteristic is exhibited in the photochromic sheet 10A, a predetermined value for clarity, which governs the degree of scattering that serves as an indicator of turbidity, is obtained. Similarly, when the second characteristic is exhibited in the photochromic sheet 10A, a predetermined value for haze, which governs the degree of scattering that serves as an indicator of transparency, is obtained.

[0034] In the first characteristic, the unit voltage (V2-V1) is preferably 5V or less, and more preferably 1V or less. In the second characteristic, the unit voltage (V2-V1) is also preferably 5V or less. Compared to the case where the unit voltage (V2-V1) is higher than 5V, even with a smaller change in the voltage value applied to the dimming sheet 10A, superior clarity in the first characteristic and superior haze in the second characteristic can be obtained. Therefore, compared to the case where the unit voltage (V2-V1) is higher than 5V, it is possible to grasp the degree of scattering in more detail in each characteristic.

[0035] As described above, in the dimming device 10 shown in Figure 1, no driving voltage is applied to the pair of transparent electrode layers 12. At this time, the orientation direction of the multiple liquid crystal molecules 11BL located within each pore 11D is random. Therefore, light incident on the dimming device 10 from either of the pair of transparent substrates 13 is scattered isotropically in the dimming layer 11. As a result, the haze value in the dimming sheet 10A is higher and the clarity value is lower compared to when a driving voltage is applied to the dimming sheet 10A. The dimming sheet 10A shown in Figure 1 has an example of the first state described above.

[0036] As described above, in the dimming sheet 10A shown in Figure 2, the drive circuit 10D applies a saturation voltage to the pair of transparent electrode layers 12. This changes the orientation of the multiple liquid crystal molecules 11BL from random orientation to, for example, a vertical orientation, which is the direction in which light is transmitted. In other words, each liquid crystal molecule 11BL is positioned within the pore 11D such that its long axis is approximately perpendicular to the plane on which the dimming layer 11 extends. Therefore, light incident on the dimming sheet 10A from either of the pair of transparent substrates 13 is transmitted through the dimming layer 11 with almost no scattering. At this time, the haze value in the dimming sheet 10A is lower and the clarity value is higher compared to when no drive voltage is applied to the dimming sheet 10A. The dimming sheet 10A shown in Figure 2 has an example of the second state described above.

[0037] [Second Structure] The second configuration of the dimming device will be described with reference to Figures 3 and 4. Figure 3 shows the second configuration of the dimming device in which no driving voltage is applied to the dimming sheet, while Figure 4 shows the second configuration of the dimming device in which a saturation voltage, which is an example of a driving voltage, is applied to the dimming sheet. In the second configuration, as the magnitude of the driving voltage applied to the dimming sheet increases, the orientation of the liquid crystal molecules changes from the orientation shown in Figure 3 to the orientation shown in Figure 4.

[0038] As shown in Figure 3, the dimming sheet 20A of the dimming device 20 comprises a dimming layer 11, a pair of transparent electrode layers 12, and a pair of transparent substrates 13, in addition to a pair of alignment layers 21. The pair of alignment layers 21 sandwich the dimming layer 11 in the thickness direction of the dimming layer 11 and are located closer to the center of the dimming sheet 20A than the pair of transparent electrode layers 12 in the thickness direction of the dimming layer 11. In other words, one alignment layer 21 is located between the dimming layer 11 and one of the transparent electrode layers 12, and the other alignment layer 21 is located between the dimming layer 11 and the other transparent electrode layer 12.

[0039] The drive circuit 10D applies a voltage such that the clarity value of the dimming sheet 20A becomes 83% or less, putting the dimming sheet 20A into a first state. The first state is opaque, for example, the most opaque state of the dimming sheet 20A. The drive circuit 10D applies a voltage such that the haze value of the dimming sheet 20A becomes 15% or less, putting the dimming sheet 20A into a second state. The second state is transparent, for example, the most transparent state of the dimming sheet 20A.

[0040] The drive circuit 10D is configured to allow selection between a first mode and a second mode of operation. The selection of the drive mode in the drive circuit 10D is performed, for example, according to the input of an external control signal.

[0041] In the first mode, the absolute value of the change in clarity value per unit voltage is greater than the absolute value of the change in haze value per unit voltage. When the drive circuit 10D is driven in the first mode, the dimming sheet 20A includes a first state and other states. The drive circuit 10D selectively applies multiple voltages at different timings such that the index parameter is less than 1, thereby putting the dimming sheet into the first state or any other state that satisfies the index parameter being less than 1. When the drive circuit 10D is driven in the first mode, the drive circuit 10D selectively applies voltages corresponding to each clarity setting.

[0042] In the second mode, the absolute value of the change in the haze value per unit voltage is greater than or equal to the absolute value of the change in the clarity value per unit voltage. When the drive circuit 10D is driven in the second mode, the dimming sheet 20A includes the second state and other states. The drive circuit 10D selectively applies multiple voltages at different timings, each with an index parameter of 1 or more, thereby putting the dimming sheet into the second state or any other state where the index parameter is 1 or more. When the drive circuit 10D is driven in the second mode, the drive circuit 10D selectively applies voltages corresponding to each set value of the haze.

[0043] In the dimming device 20, similar to the dimming device 10, the dimming sheet 20A exhibits either a first characteristic or a second characteristic. In the first characteristic, the absolute value of the change in clarity value per unit voltage is greater than the absolute value of the change in haze value per unit voltage. In the first characteristic, the unit voltage (V2-V1) is preferably 5V or less, and more preferably 1V or less. In the second characteristic, the absolute value of the change in haze value per unit voltage is greater than or equal to the absolute value of the change in clarity value per unit voltage. In the second characteristic, the unit voltage (V2-V1) is preferably 5V or less.

[0044] Furthermore, the drive circuit 10D, similar to the drive circuit 10D of the dimming device 10, causes the dimming sheet 20A to exhibit a first characteristic by applying a drive voltage corresponding to a predetermined value in clarity between the transparent electrode layers 12. In addition, the drive circuit 10D causes the dimming sheet 20A to exhibit a second characteristic by applying a drive voltage corresponding to a predetermined value in haze between the transparent electrode layers 12.

[0045] When each alignment layer 21 is a vertical alignment layer, the orientation of the liquid crystal molecules 11BL contained in each pore 11D is vertical when no driving voltage is applied to the dimming sheet 20A. In other words, each liquid crystal molecule 11BL is located in the pore 11D such that its long axis is approximately perpendicular to the plane on which the dimming layer 11 extends. Therefore, light incident on the dimming sheet 20A from either of the pair of transparent substrates 13 is transmitted through the dimming layer 11 with almost no scattering. As a result, the haze value in the dimming sheet 20A is lower and the clarity value is higher compared to when no driving voltage is applied to the dimming sheet 20A. The dimming sheet 20A shown in Figure 3 has an example of the second state described above.

[0046] As described above, in the dimming sheet 20A shown in Figure 4, a saturation voltage is applied to a pair of transparent electrode layers 12. This changes the orientation of multiple liquid crystal molecules 11BL. For example, the orientation of multiple liquid crystal molecules 11BL changes from vertical to horizontal. At this time, each liquid crystal molecule 11BL is positioned within the pore 11D such that the long axis of the liquid crystal molecule 11BL extends along the plane on which the dimming layer 11 extends. Therefore, light incident on the dimming sheet 20A from either of the pair of transparent substrates 13 is scattered in the dimming layer 11. At this time, the haze value in the dimming sheet 20A increases and the clarity value decreases compared to when no driving voltage is applied to the dimming sheet 20A. The dimming sheet 20A shown in Figure 4 has an example of the first state described above.

[0047] [How to calculate clarity] The method for calculating clarity will be explained with reference to Figure 5. Figure 5 schematically shows an example of a measuring device used for calculating clarity.

[0048] As shown in FIG. 5, the clarity measuring device 40 includes an irradiation unit 41, a light receiving unit 42, and an integrating sphere 43. The irradiation unit 41 includes a light source 41A and a lens 41B. The light source 41A is a white LED, and the lens 41B converts the light emitted by the light source 41A into parallel light. The light receiving unit 42 includes a central sensor 42C and an outer peripheral sensor 42R. The central sensor 42C and the outer peripheral sensor 42R each have an annular shape. The outer peripheral sensor 42R is located outside the central sensor 42C. Note that the measuring device 40 can be used not only to measure the clarity of the measurement object but also to measure haze. The integrating sphere 43 of the measuring device 40 is used only when measuring haze.

[0049] In the measuring device 40, the dimming sheets 10A and 20A are disposed between the irradiation unit 41 and the integrating sphere 43. In this embodiment, the diameter of the light beam of the parallel light emitted from the lens 41B is 14 mm. The light transmitted through the dimming sheets 10A and 20A includes a straight - traveling light LS that travels straight along the traveling direction of the parallel light LP incident on the dimming layer 11, and a narrow - angle scattered light LNS whose angle with respect to the traveling direction of the parallel light LP is within ±2.5°. In the light receiving unit 42, the central sensor 42C receives the straight - traveling light LS, and the outer peripheral sensor 42R receives the narrow - angle scattered light LNS. The amount of light of the straight - traveling light LS received by the central sensor 42C is set to L C and the amount of light of the narrow - angle scattered light LNS received by the outer peripheral sensor 42R is set to L R .

[0050] The clarity is calculated by the following formula (1) when the amount of light of the straight - traveling light LS that travels straight along the traveling direction of the parallel light LP incident on the dimming layer 11 among the light transmitted through the dimming layer 11 is the light amount L C and the amount of light of the narrow - angle scattered light LNS whose angle with respect to the traveling direction of the parallel light LP is within ±2.5° is the light amount L R . 100×(L C - L R ) / (L C + L R ) … Formula (1)

[0051] Thus, clarity is a parameter used to evaluate the state of the dimming sheets 10A and 20A using narrow-angle scattered light. Therefore, clarity allows us to evaluate how sharp the very minute details of an object are in the image of the object seen through the dimming sheets 10A and 20A. Consequently, when an observer views an object through the dimming sheets 10A and 20A, the smaller the clarity value of the dimming sheets 10A and 20A, the more blurred the outline of the object becomes through the dimming sheets 10A and 20A; in other words, the sharpness of the object decreases. Thus, clarity evaluates the sharpness of the image of an object viewed through the dimming sheets 10A and 20A.

[0052] [How to calculate haze] Using the light intensity measured with the measuring device 40, it is possible to calculate the haze in the dimming sheets 10A and 20A. As described above, the haze is calculated according to the method conforming to JIS K 7136:2000. When measuring the haze using the measuring device 40, the light transmitted through the dimming sheets 10A and 20A is received by the light receiving unit placed inside the integrating sphere 43.

[0053] Haze is the percentage of transmitted light passing through dimming sheets 10A and 20A that deviates more than 2.5° from the incident light due to forward scattering. In other words, in haze measurement, light with an angle of ±2.5° or less with respect to the direction of propagation of the parallel light LP is considered parallel light, and light with an angle greater than ±2.5° is considered wide-angle scattered light. The transmittance of wide-angle scattered light is called the diffuse transmittance T. d Let the transmittance of parallel light be defined as the parallel light transmittance T. p Let the parallel light transmittance T be considered. p and diffuse transmittance T d The sum of these is the total light transmittance T t Let's assume that haze is the total light transmittance T. t Internal diffuse transmittance T d This is the proportion.

[0054] Thus, haze is a parameter used to evaluate the state of the dimming sheets 10A and 20A using wide-angle scattered light. Therefore, haze allows the observer to evaluate the overall degree of turbidity of the dimming sheets 10A and 20A as perceived by the observer when the dimming sheets are observed visually. Consequently, when an observer views an object through the dimming sheets 10A and 20A, the larger the haze value of the dimming sheets 10A and 20A, the lower the contrast between the object seen through the dimming sheets 10A and 20A and its surroundings, causing the object to appear hazy to the observer.

[0055] Furthermore, in the dimming sheets 10A and 20A, within the entire range of the drive voltage applied to the dimming sheets 10A and 20A, in mutually different ranges, the absolute value of the change in clarity per unit voltage is greater than the absolute value of the change in haze per unit voltage. Within the entire range of the drive voltage applied to the dimming sheets 10A and 20A, in the first range, the absolute value of the change in clarity per unit voltage is greater than the absolute value of the change in haze per unit voltage, and in the second range, which is different from the first range, the absolute value of the change in haze per unit voltage is greater than the absolute value of the change in clarity per unit voltage.

[0056] Furthermore, when the drive voltage included in the first range is applied to the dimming sheets 10A and 20A, the haze value is higher and the clarity value is lower compared to when the drive voltage included in the second range is applied to the dimming sheets 10A and 20A. In other words, when the drive voltage included in the first range is applied to the dimming sheets 10A and 20A, the transmittance of the dimming sheets 10A and 20A is lower compared to when the drive voltage included in the second range is applied to the dimming sheets 10A and 20A.

[0057] In other words, when a drive voltage included in the second range is applied to dimming sheets 10A and 20A, the haze value is lower and the clarity value is higher compared to when a drive voltage included in the first range is applied to dimming sheets 10A and 20A. In other words, when a drive voltage included in the second range is applied to dimming sheets 10A and 20A, the transmittance of dimming sheets 10A and 20A is higher compared to when a drive voltage included in the first range is applied to dimming sheets 10A and 20A.

[0058] Therefore, for example, during the manufacturing of dimmable sheets 10A and 20A, in ranges where the transmittance of dimmable sheets 10A and 20A is relatively low, it is possible to suppress variations in the performance of dimmable sheets 10A and 20A when they are in a specific driving state by managing the performance of dimmable sheets 10A and 20A using the clarity value. Conversely, in ranges where the transmittance of dimmable sheets 10A and 20A is relatively high, it is possible to suppress variations in the performance of dimmable sheets 10A and 20A when they are in a specific driving state by managing the performance of dimmable sheets 10A and 20A using the haze value.

[0059] As a result, it is possible to minimize discrepancies in object recognition when viewed through dimmable sheets 10A and 20A during the manufacturing process, even between different products. Furthermore, for example, when driving dimmable sheets 10A and 20A, in ranges where the transmittance of dimmable sheets 10A and 20A is relatively low, it is possible to suppress variations in the performance of dimmable sheets 10A and 20A when they are in a specific driving state by controlling the magnitude of the driving voltage applied to dimmable sheets 10A and 20A using the clarity value. Conversely, in ranges where the transmittance of dimmable sheets 10A and 20A is relatively high, it is possible to suppress variations in the performance of dimmable sheets 10A and 20A when they are in a specific driving state by controlling the magnitude of the driving voltage applied to dimmable sheets 10A and 20A using the haze value.

[0060] As a result, when the dimming sheets 10A and 20A are driven with stepwise control of the dimming sheets 10A and 20A, it is possible to suppress discrepancies in the recognition of objects seen through the dimming sheets 10A and 20A.

[0061] [Examples] The following describes an example of a dimming device. A dimmable sheet having a polymer network type dimmable layer was prepared. A dimming device was obtained by electrically connecting a drive circuit that outputs a drive voltage to the dimmable sheet. In this embodiment, a dimmable sheet included in the dimming device having the first configuration described above was prepared. The haze value and clarity value of the dimmable sheet were measured while changing the magnitude of the drive voltage applied to the dimmable sheet.

[0062] Using a haze meter (NDH7000SP, manufactured by Nippon Denshoku Industries Co., Ltd.), JIS K The haze value of the dimmable sheet was measured according to a method compliant with 7136:2000. The clarity value of the dimmable sheet was also measured using a haze / clarity meter (HazeGuard i, BYK-Gardner) according to the measurement method described above. From the measured haze and clarity values, the absolute value |ΔH / ΔC|, the ratio of the change in haze value per unit voltage to the change in clarity value per unit voltage ΔC, was calculated.

[0063] The measurement results for haze and clarity are shown in Figure 6 and Table 1. The calculation results for each setting value are also shown in Table 1. Note that the "*" mark in Table 1 indicates that the change in clarity value ΔC per unit voltage is zero. In Figure 6, the area enclosed by the solid line shows the relationship between the haze value and clarity value obtained when a drive voltage of any magnitude within the range of 0V to 12V is applied to the dimming sheet. In Figure 6, the area enclosed by the dashed line shows the relationship between the haze value and clarity value obtained when a drive voltage of any magnitude within the range of 13V to 100V is applied to the dimming sheet. In Figure 6, the slope of the absolute value |ΔH / ΔC|, which is the ratio of the change in haze value ΔH per unit voltage to the change in clarity value ΔC per unit voltage, is the same as the slope of the graph consisting of the haze value and the clarity value.

[0064] [Table 1]

[0065] As shown in Figure 6, when the drive voltage applied to the dimming sheet falls within the range of 0V to 12V, the clarity value changes sharply as the magnitude of the drive voltage changes, while the haze value remains almost unchanged even when the magnitude of the drive voltage changes.

[0066] In contrast, when the drive voltage applied to the dimming sheet falls within the range of 13V to 100V, it was observed that the haze value changes sharply as the magnitude of the drive voltage changes, while the clarity value remains almost unchanged even when the magnitude of the drive voltage changes.

[0067] Furthermore, it was observed that the absolute value of the ratio of the change in haze value per unit voltage to the change in clarity value per unit voltage approaches 0 as the clarity value decreases.

[0068] As shown in Table 1, when any drive voltage within the range of 0V to 10V was applied to the dimming sheet, the clarity value was found to be 83% or less. Furthermore, when any drive voltage within the range of 35V to 100V was applied to the dimming sheet, the haze value was found to be 15% or less.

[0069] Furthermore, as shown in Table 1, when any drive voltage within the range of 0V to 12V is applied to the dimming sheet, the absolute value of the ratio of the change in haze value per unit voltage to the change in clarity value per unit voltage was found to be less than 1. In other words, the absolute value of the change in clarity value per unit voltage was found to be greater than the absolute value of the change in haze value per unit voltage.

[0070] In contrast, when any driving voltage within the range of 13V to 100V is applied to the dimming sheet, it was found that the absolute value of the ratio of the change in haze value per unit voltage to the change in clarity value per unit voltage is 1 or greater. In other words, it was found that the absolute value of the change in haze value per unit voltage is greater than or equal to the absolute value of the change in clarity value per unit voltage.

[0071] As described above, according to one embodiment of the dimming device, the following effects can be obtained. (1) In the first state of the dimmable sheets 10A and 20A, the clarity value, which depends on narrow-angle scattering where the scattering angle of light incident on the dimmable sheets 10A and 20A is 2.5° or less, is 83% or less. Therefore, the degree of scattering in the dimmable sheets 10A and 20A indicates sufficient opacity for recognizing objects seen through the dimmable sheets 10A and 20A. Then, in the second state of the dimmable sheets 10A and 20A, the haze value, which depends on wide-angle scattering where the scattering angle of light incident on the dimmable sheets 10A and 20A is greater than 2.5°, is 15% or less. Therefore, the degree of scattering in the dimmable sheets 10A and 20A indicates sufficient transparency for recognizing objects seen through the dimmable sheets 10A and 20A. Thus, compared to a configuration in which the degree of scattering is determined by a single parameter such as haze, it is possible to suppress discrepancies in object recognition seen through the dimmable sheets 10A and 20A.

[0072] (2) When the dimming sheets 10A and 20A are driven in the first mode, the voltage applied between the first transparent electrode layer 12A and the second transparent electrode layer 12B is a value corresponding to the clarity setting value. That is, in the dimming sheets 10A and 20A driven in the first mode, each clarity setting value that governs the change in the degree of scattering is obtained by applying a voltage. As a result, it becomes possible to select a preset degree of scattering without causing a discrepancy in the recognition of objects seen through the dimming sheets 10A and 20A.

[0073] (3) When the dimming sheets 10A and 20A are driven in the second mode, the voltage applied between the first transparent electrode layer 12A and the second transparent electrode layer 12B is a value corresponding to the haze setting value. That is, in the dimming sheets 10A and 20A driven in the second mode, each haze setting value that governs the change in the degree of scattering is obtained by applying a voltage. As a result, it becomes possible to select a preset degree of scattering without causing a discrepancy in the recognition of objects seen through the dimming sheets 10A and 20A.

[0074] (4) When the dimming sheets 10A and 20A are transparent, it becomes possible to enhance the effectiveness of obtaining the separation suppression effect in accordance with (1) above. (5) When the dimming sheets 10A and 20A are opaque, it becomes possible to enhance the effectiveness of obtaining the discrepancy suppression effect in accordance with (1) above.

[0075] The above embodiment can be implemented with the following modifications. [Drive circuit] • When the drive circuit 10D causes the dimming sheets 10A and 20A to exhibit a first state, it is not necessary to apply a drive voltage corresponding to a predetermined value in clarity to the dimming sheets 10A and 20A. In this case, the drive circuit 10D may apply a drive voltage corresponding to a predetermined value in haze.

[0076] Furthermore, when the drive circuit 10D causes the dimming sheets 10A and 20A to exhibit a second state, it is not necessary to apply a drive voltage corresponding to a predetermined value in the haze to the dimming sheets 10A and 20A. In this case, the drive circuit 10D may apply a drive voltage corresponding to a predetermined value in the clarity.

[0077] Even in these cases, the drive circuit 10D can switch the state of the dimming sheets 10A and 20A between the first state and the second state, thereby suppressing, for example, the occurrence of misalignment between the dimming sheets during the manufacturing stage of the dimming sheets 10A and 20A. Therefore, it is possible to obtain some effect similar to that described in (1) above.

[0078] The drive circuit 10D may be capable of switching the state of the dimming sheets 10A and 20A to three or more states, including a first state and a second state. In this case, the drive circuit 10D can change the state of the dimming sheets 10A and 20A to a third state in which the clarity value falls within the range between the value in the first state and the value in the second state, and the haze value also falls within the range between the value in the first state and the value in the second state. The drive circuit 10D can set the state of the dimming sheets 10A and 20A to a third state by applying a drive voltage to the dimming sheets 10A and 20A that is different from the drive voltage used when setting the dimming sheets 10A and 20A to the first state and the drive voltage used when setting them to the second state.

[0079] The dimming devices 10 and 20 may further include a control unit that controls the driving of the dimming devices 10 and 20 in order to change the transmittance of the dimming sheets 10A and 20A. In this case, the control unit includes information such as a table for converting mutually different haze values ​​into driving voltages to bring the dimming sheets 10A and 20A to a second state, and applies a driving voltage to the driving circuit that corresponds to the haze specified by an external operating device. In addition, the control unit includes information such as a table for converting mutually different clarity values ​​into driving voltages to bring the dimming sheets 10A and 20A to a first state, and applies a driving voltage to the driving circuit that corresponds to the clarity specified by an external operating device. With dimming devices 10 and 20 equipped with such a control unit, the effectiveness of suppressing discrepancies can be increased.

[0080] [Dimmable sheet] The dimming sheets 10A and 20A may have characteristics different from the first and second characteristics. In this case, the dimming sheets 10A and 20A can exhibit the first characteristic and, for example, a third characteristic by changing the mixing ratio of the liquid crystal composition 11B in the dimming layer 11. Furthermore, in dimming sheets 10A and 20A that have spacers in the dimming layer to maintain a gap between a pair of transparent electrode layers, the first characteristic and, for example, a third characteristic can be exhibited by changing the density of the spacers in the dimming layer. In the third characteristic, the amount of change in the clarity value per unit voltage is approximately equal to the amount of change in the haze value per unit voltage.

[0081] The unit voltage can be any value within the range of 5V to 10V. Regardless of which value within the above range is used as the unit voltage, the drive circuit 10D can obtain the effect described in (1) above by switching the state of the dimming sheets 10A and 20A between the first state and the second state.

[0082] The shape of the dimming sheets 10A and 20A may be planar, curved with curvature in two dimensions, or curved with curvature in three dimensions. The dimming sheets 10A and 20A can be provided with a flexible transparent substrate 13. In this case, the dimming sheets 10A and 20A also show excellent adaptability to curved surface processing.

[0083] [Light-regulating layer] The dimming layer 11 is not limited to polymer network type liquid crystal. The dimming layer 11 may be, for example, polymer dispersed liquid crystal (PDCL) or encapsulated nematic liquid crystal (NCAP).

[0084] The dimming layer 11 may contain a dichroic dye and exhibit a predetermined color derived from the dichroic dye. Even in this case, if the drive circuit 10D is configured to switch the state of the dimming sheets 10A and 20A between a first state and a second state, the effects similar to those described in (1) above can be obtained. [Explanation of symbols]

[0085] 10, 20... Dimming device, 10A, 20A... Dimming sheet, 10D... Drive circuit, 11... Dimming layer, 11A... Polymer network, 11B... Liquid crystal composition, 11BL... Liquid crystal molecule, 11D... Pore, 12... Transparent electrode layer, 13... Transparent substrate, 21... Alignment layer, 40... Measuring device, 41A... Light source, 41... Irradiation unit, 41B... Lens, 42... Light receiving unit, 42C... Central sensor, 42R... Peripheral sensor, 43... Integrating sphere.

Claims

1. A light-adjusting sheet comprising a first transparent electrode layer, a second transparent electrode layer, and a light-adjusting layer, wherein the light-adjusting layer contains liquid crystal molecules and is located between the first transparent electrode layer and the second transparent electrode layer, The device includes a drive circuit configured to change the voltage applied between the first transparent electrode layer and the second transparent electrode layer, thereby switching the state of the dimming sheet between a first state, which is opaque, and a second state, which is transparent, by changing the voltage applied between the first and second transparent electrode layers and switching the orientation of the liquid crystal molecules according to the value of the voltage. The light-adjusting layer comprises a polymer layer and a liquid crystal composition containing the liquid crystal molecules, The aforementioned drive circuit is A voltage is applied such that the clarity value of the dimming sheet becomes 83% or less, thereby setting the dimming sheet to the first state. A voltage is applied to the dimming sheet such that the haze value of the dimming sheet conforming to JIS K 7136 becomes 15% or less, thereby putting the dimming sheet into the second state. When a voltage of 35V to 100V is applied, the haze value is 15% or less. When a voltage of 12V to 100V is applied, the clarity value is 90% or more. The clarity is the amount of light L of the straight-traveling light that travels in a straight line along the direction of propagation of parallel light incident on the dimming sheet, in the light transmitted through the dimming sheet so as to be in the direction normal to the plane on which the dimming sheet extends. Ｃ The amount of light L of narrow-angle scattered light, where the angle of the parallel light with respect to the direction of propagation is within ±2.5°, is determined as follows: Ｒ In this case, it is calculated by the following formula (1): 100×(L) Ｃ -L Ｒ ) / (L Ｃ +L Ｒ Equation (1) The drive circuit drives the dimming sheet in the first mode, The first mode includes the absolute value of the change in the clarity value per unit voltage being greater than the absolute value of the change in the haze value per unit voltage, and the dimming sheet being in the first state. The drive circuit selectively applies voltages corresponding to each clarity setting value, which is set within the range of clarity values ​​that indicate the dimming sheet is in the first state. Dimming device.

2. The aforementioned drive circuit drives the dimming sheet in a second mode, The second mode includes the absolute value of the change in the haze value per unit voltage being greater than or equal to the absolute value of the change in the clarity value per unit voltage, and the dimming sheet being in the second state. The drive circuit selectively applies voltages corresponding to each set value of the haze, which is set within the range of the haze values ​​that indicate the dimming sheet is in the second state. The dimming device according to claim 1.

3. The drive circuit applies a voltage in a range where the absolute value of the ratio of the change in the haze value per unit voltage of 5V to the change in the clarity value per unit voltage of 5V is 80 or more, either continuously or intermittently, to bring the dimming sheet to the second state. A dimming device according to claim 1 or 2.

4. The drive circuit applies a voltage such that the absolute value of the ratio of the change in the haze value per unit voltage of 1V to the change in the clarity value per unit voltage of 1V is 0.1 or less, thereby setting the dimming sheet to the first state. A dimming device according to any one of claims 1 to 3.

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