Test image display body, characteristic index value calculation system, and characteristic index value calculation method

Abstract

To provide a test image display body for evaluating an optical characteristic of a light control sheet, and a characteristic index value calculation method.SOLUTION: A test image a test image display body displays consists of: three first straight lines 11A; three second straight lines 11B; and three third straight lines 11C, in which the straight lines do not intersect mutually. The first straight lines 11A extend a tangential direction of a first circle internally contacting with the three first straight lines 11A, and are equally disposed in a circumferential direction of the first circle. The second straight lines 11B internally contact with the three second straight lines, extend a contact line direction of a second circle concentric with the first circle, and are equally disposed in a circumferential direction of the second circle so that the second straight lines 11B are located one by one among the mutually adjacent first straight lines 11A in the circumferential direction of the second circle. A diameter of the first circle is shorter than that of the second circle, and the third straight lines 11C are located outward in a radial direction of the second circle, and located on a normal line of the first straight lines 11A.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a test image display medium, a characteristic index value calculation system, and a characteristic index value calculation method used to evaluate the optical characteristics of a light-modulating sheet. [Background technology]

[0002] The visibility of the object being shielded through a light-controlling sheet that has a liquid crystal compound between transparent electrodes depends on the orientation direction of the liquid crystal compound. Stabilizing the orientation direction and improving the reproducibility of the orientation direction will accelerate the spread of light-controlling sheets. Haze according to JIS K 7136:2000 is used as an index related to the optical properties of light-controlling sheets. For example, a haze of 95% or more when opaque and 12% or less when transparent are set as control items for light-controlling sheets (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6493598 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, the use of characteristic indices that require dedicated optical equipment to obtain index values ​​limits the acquisition of optical properties to the manufacturing process of light-adjusting films. For example, in the manufacturing process of light-adjusting films, index values ​​can be obtained by installing dedicated optical equipment such as integrating spheres and detectors in light-adjusting film inspection facilities. However, when light-adjusting films are attached to office partitions or vehicle windows, it is not even possible to install dedicated optical equipment such as integrating spheres and detectors at the installation site where the light-adjusting film is attached. Therefore, there is a strong need to develop new indices that can evaluate the optical properties of light-adjusting films in the various situations in which they are used. [Means for solving the problem]

[0005] The test image display for solving the above problem is a test image display that displays a test image used to calculate a characteristic index value that represents the optical characteristics of a light-adjusting sheet. The captured image is an image of the test image captured through the light-adjusting sheet, and the characteristic index value indicates the magnitude of the radial distribution in a predetermined frequency band obtained by two-dimensional Fourier transform using the captured image. The test image is composed of a plurality of straight lines, each of which is spaced apart from the other straight lines, and the extension of each straight line intersects with the extension of another straight line adjacent to the straight line, and the plurality of straight lines include a plurality of first straight lines arranged with gaps in the circumferential direction of a first circle, each of which extends in a direction different from the radial direction of the first circle; a plurality of second straight lines arranged with gaps in the circumferential direction of a second circle surrounding the first circle, each of which extends in a direction different from the radial direction of the second circle; and a plurality of third straight lines arranged with gaps in the circumferential direction of a third circle surrounding the first circle, each of which faces a gap between the first straight lines in the radial direction of the first circle, and each of which faces a first straight line in the radial direction of the first circle.

[0006] A characteristic index value calculation system for solving the above problem is a characteristic index value calculation system that calculates a characteristic index value that represents the optical characteristics of a light-modulating sheet. The characteristic index value calculation system includes an acquisition unit that acquires a photographed image of a test image in a predetermined environment photographed through the light-modulating sheet, and a calculation unit that calculates the characteristic index value that represents the magnitude of the radial distribution in a predetermined frequency band by performing a two-dimensional Fourier transform using the photographed image acquired by the acquisition unit. The test image is composed of a plurality of straight lines, each of which is spaced apart from the other straight lines and whose extensions intersect with the extensions of the other straight lines adjacent to the first straight line, and the plurality of straight lines comprises: a plurality of first straight lines arranged with gaps in the circumferential direction of a first circle, each of which extends in a direction different from the radial direction of the first circle; a plurality of second straight lines arranged with gaps in the circumferential direction of a second circle surrounding the first circle, each of which extends in a direction different from the radial direction of the second circle; and a plurality of third straight lines arranged with gaps in the circumferential direction of a third circle surrounding the first circle, each of which faces a gap between the first straight lines in the radial direction of the first circle, and each of which faces a first straight line in the radial direction of the first circle.

[0007] A characteristic index value calculation method for solving the above problem is a characteristic index value calculation method for calculating a characteristic index value that represents the optical characteristics of a light-adjusting sheet, and includes obtaining a photographed image of a test image in a specified environment photographed through the light-adjusting sheet, and calculating the characteristic index value that indicates the magnitude of the radial distribution in a specified frequency band by two-dimensional Fourier transform using the photographed image. The test image is composed of a plurality of straight lines, each of which is spaced apart from the other straight lines, and the extension of each straight line intersects with the extension of another straight line adjacent to the straight line, and the plurality of straight lines include a plurality of first straight lines arranged with gaps in the circumferential direction of a first circle, each of which extends in a direction different from the radial direction of the first circle; a plurality of second straight lines arranged with gaps in the circumferential direction of a second circle surrounding the first circle, each of which extends in a direction different from the radial direction of the second circle; and a plurality of third straight lines arranged with gaps in the circumferential direction of a third circle surrounding the first circle, each of which faces a gap between the first straight lines in the radial direction of the first circle, and each of which faces a first straight line in the radial direction of the first circle.

[0008] A characteristic index value calculation method for solving the above problem is a characteristic index value calculation method for calculating a characteristic index value that represents the optical characteristics of a light-adjusting sheet, and includes obtaining a photographed image of a test image in a specified environment photographed through the light-adjusting sheet, and calculating the characteristic index value that indicates the magnitude of the radial distribution in a specified frequency band by a two-dimensional Fourier transform using the photographed image, wherein the test image is composed of a plurality of straight lines, each of which is spaced apart from the other straight lines, and the extensions of each of the straight lines intersect with the extensions of other straight lines adjacent to the straight line, and when the intensity of the radial distribution is normalized with the maximum value of the intensity in the radial distribution set to 1, the difference in peak intensity values ​​between adjacent peaks in the specified frequency band is 0.2 or less.

[0009] According to each of the above configurations, the magnitude of the radial distribution in a predetermined frequency band is calculated as a characteristic index value by two-dimensional Fourier transform using a captured image. A test image is then constructed from lines that are spaced apart and have non-parallel adjacent lines, and an image of the test image captured through a light-adjusting sheet is used as the captured image. In this case, the test image is captured using a general-purpose imaging device such as a smartphone, tablet, or digital camera, rather than a dedicated optical device such as an integrating sphere. The magnitude of the radial distribution in a predetermined frequency band tends to increase as the haze of the light-adjusting sheet increases, making it easy to synchronize with the haze change of the light-adjusting sheet. Therefore, each of the above configurations enables the diversification of characteristic indexes that represent the optical characteristics of the light-adjusting sheet. Furthermore, if the multiple lines constituting the test image satisfy the above-described relationship, the optical characteristics of the light-adjusting sheet can be evaluated with high accuracy.

[0010] In the above test image display, the plurality of straight lines may be composed of three first straight lines evenly spaced on the first circle, three second straight lines evenly spaced on the second circle, and three third straight lines evenly spaced on the third circle.

[0011] In the test image display, the third straight line may be positioned on a normal line to the first straight line. The test image display may be configured such that the second lines face each other in the gaps between the first lines that are adjacent to each other in the circumferential direction of the first circle, so that the bisector of the angle formed by the first lines that are adjacent to each other in the circumferential direction of the first circle passes through the center of the second line in the direction in which the second line extends.

[0012] These configurations can effectively improve the accuracy of evaluation of optical characteristics. In the test image display, the first straight line may be longer than the third straight line and shorter than the diameter of the first circle, the second straight line may be longer than the diameter of the first circle and shorter than the diameter of the second circle, and the third straight line may be longer than the radius of the first circle. This configuration improves the effectiveness of improving the accuracy of evaluation of optical characteristics that depend on the lengths of the straight lines.

[0013] In the test image display, the diameter of the first circle may be between 1 / 3 and 1 / 2 of the diameter of the second circle. This configuration improves the effectiveness of improving the accuracy of evaluation of optical characteristics that depend on the relative positions of the first and second straight lines.

[0014] In the test image display, the distance between adjacent lines among the plurality of lines may be 2 mm or more and 4 mm or less. This configuration improves the effectiveness of improving the accuracy of evaluation of optical characteristics that depend on the distance between the lines constituting the test image.

[0015] In the test image display, the width of the first straight line may be equal to the width of the second straight line, and the width of the second straight line may be equal to the width of the third straight line. This configuration improves the effectiveness of improving the accuracy of evaluation of optical characteristics that depend on the difference in width between the straight lines that make up the test image.

[0016] In the test image display, the width of the straight line may be 0.2 mm or more and 1 mm or less. This configuration increases the effectiveness of improving the accuracy of evaluation of optical characteristics that depend on the width of the straight line that constitutes the test image.

[0017] In the characteristic index value calculation method, the range of the characteristic index value when the optical characteristics of the light controlling sheet are normal may be a normal range, and the optical characteristics of the light controlling sheet may be determined to be normal when the characteristic index value calculated using the captured image is within the normal range. According to this method, it is possible to determine that the optical characteristics of the light controlling sheet are normal from the captured image of the test image. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a configuration diagram showing an example of an apparatus used in the characteristic index value calculation method. [Figure 2] FIG. 2 is a power spectrum diagram showing an example of extraction of a sample group for calculating a characteristic index value. [Figure 3] FIG. 3 is a diagram showing a captured image example 1. As shown in FIG. [Figure 4] FIG. 4 is a power spectrum diagram of the photographed image example 1. In FIG. [Figure 5] FIG. 5 is a diagram showing a captured image example 2. In FIG. [Figure 6] FIG. 6 is a power spectrum diagram of the captured image example 2. [Figure 7] FIG. 7 is a diagram showing a photographed image example 3. In FIG. [Figure 8] FIG. 8 is a power spectrum diagram of the photographed image example 3. [Figure 9] FIG. 9 is a diagram showing a captured image example 4. In FIG. [Figure 10] FIG. 10 is a power spectrum diagram of the captured image example 4. [Figure 11] FIG. 11 is a diagram showing a photographed image example 5. In FIG. [Figure 12] FIG. 12 is a power spectrum diagram of the photographed image example 5. [Figure 13] FIG. 13 is a graph showing the relationship between the characteristic index value and haze. [Figure 14] FIG. 14 is a plan view of a light-control sheet showing the electrode arrangement for evaluation. [Figure 15] FIG. 15 is a graph showing the relationship between voltage and characteristic value as an evaluation example. [Figure 16] FIG. 16 is a diagram showing an example of dimensions of the photographed image example 1. In FIG. [Figure 17] FIG. 17 is a graph showing the relationship between the number of pixels and pixel brightness for each dimension of the captured image example 1. [Figure 18] FIG. 18 is a graph showing the relationship between clarity and image blur. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of a test image display body, a characteristic index value calculation system, and a characteristic index value calculation method will be described. First, the configuration of the light-modulating sheet to be evaluated and the characteristic index value calculation system will be described. Next, the image analysis used in the characteristic index value calculation method and the evaluation sample extracted in the image analysis will be described. Next, the test image to be captured will be described.

[0020] [Light Control Sheet 101] 1, the light controlling sheet 101 is configured to be able to change the light transmittance. The light transmittance of the light controlling sheet 101 is changed by changing the drive voltage applied to the light controlling sheet 101.

[0021] The light controlling sheet 101 is attached to a transparent body 102. The transparent body 102 may be a window installed in various buildings such as commercial facilities or public facilities. The transparent body 102 may be a partition installed in an office or medical facility. The transparent body 102 may be a show window installed in an exhibition facility or cultural facility. The transparent body 102 may be the base material of a screen for projecting images. The transparent body 102 may be a window installed in a moving object such as a vehicle or an aircraft. The light controlling sheet 101 may be attached by being attached to the surface of the transparent body 102, or by being sandwiched between two transparent bodies 102 such as laminated glass. Note that FIG. 1 shows an example in which the light controlling sheet 101 is attached to the transparent body 102.

[0022] The shape of the light controlling sheet 101 may be flat, following the outer shape of the transparent body 102, or may be a two-dimensional curved shape such as a cylindrical shape or an elliptical cylindrical shape, or a three-dimensional curved shape such as a spherical shape or an ellipsoidal shape, or may be an irregular shape other than a geometric shape. The light controlling sheet 101 is colorless and transparent or colored and transparent when it has the highest light transmittance possible for the light controlling sheet 101. The light controlling sheet 101 is achromatic or chromatic when it has the lowest light transmittance possible for the light controlling sheet 101.

[0023] The light controlling sheet 101 is of either a normal type or a reverse type. A normal type light controlling sheet 101 has a relatively high light transmittance when the light controlling sheet 101 is energized, but has a relatively low light transmittance when the light controlling sheet 101 is not energized. A reverse type light controlling sheet 101 has a relatively low light transmittance when the light controlling sheet 101 is energized, but has a relatively high light transmittance when the light controlling sheet 101 is not energized.

[0024] The light-controlling sheet 101 includes a first transparent electrode, a second transparent electrode, and a light-controlling layer. The first transparent electrode, the second transparent electrode, and the light-controlling layer extend in the plane direction of the light-controlling sheet 101. The light-controlling layer is located between the first transparent electrode and the second transparent electrode in the thickness direction of the light-controlling sheet 101. The first transparent electrode and the second transparent electrode are each connected to a driving device for the light-controlling sheet 101. The driving device for the light-controlling sheet 101 applies a driving voltage to the light-controlling layer via the first transparent electrode and the second transparent electrode.

[0025] The first transparent electrode and the second transparent electrode each have optical transparency that allows visible light to pass through. The optical transparency of the first transparent electrode and the optical transparency of the second transparent electrode each enable visual recognition of the shielded object through the light-controlling sheet 101. The shielded object is a static or moving object that has a shape and exists in space, and a transparent object other than the light-controlling sheet 101 may or may not exist between the light-controlling sheet 101 and the object. The shielded object may be a living organism such as a human, or a non-living object.

[0026] An example of a material for forming the transparent electrode is at least one selected from the group consisting of indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, and poly(3,4-ethylenedioxythiophene).

[0027] The liquid crystal light control layer of the liquid crystal light control sheet contains a liquid crystal composition, and an example of the liquid crystal compound contained in the liquid crystal composition is at least one selected from the group consisting of Schiff bases, azo compounds, azoxy compounds, biphenyl compounds, terphenyl compounds, benzoates, tolan compounds, pyrimidine compounds, cyclohexanecarboxylic acid ester compounds, phenylcyclohexane compounds, and dioxane compounds. The liquid crystal composition is held in liquid crystal light control sheets in various types, including polymer dispersion and capsule types. The polymer dispersion type holds the liquid crystal composition in numerous voids dispersed in a polymer layer. The polymer dispersion type includes the polymer network type, which has a three-dimensional mesh-like polymer network. The polymer network type holds the liquid crystal composition in mesh-like voids. The capsule type holds the liquid crystal composition in a capsule-like shape in a polymer layer.

[0028] The reverse-type liquid crystal light control sheet further includes an alignment film between the light control layer and the first transparent electrode, and between the light control layer and the second transparent electrode. Examples of materials that can be used to form the alignment film include organic compounds such as polyimide, polyamide, polyvinyl alcohol, and cyanide compounds, inorganic compounds such as silicone, silicon oxide, and zirconium oxide, and mixtures of these.

[0029] The alignment film is either a vertical alignment film or a horizontal alignment film. A vertical alignment film aligns the long axis of the liquid crystal compound so that the long axis of the liquid crystal compound is perpendicular to the surface of the vertical alignment film opposite to the surface that contacts the first transparent electrode, or the surface of the vertical alignment film opposite to the surface that contacts the second transparent electrode. A horizontal alignment film aligns the long axis of the liquid crystal compound so that the long axis of the liquid crystal compound is approximately parallel to the surface of the horizontal alignment film opposite to the surface that contacts the first transparent electrode, or the surface of the horizontal alignment film opposite to the surface that contacts the second transparent electrode.

[0030] The light-controlling layer of the electrochromic sheet includes an electrochromic material and an electrolyte. Examples of the electrochromic material are organic compounds or inorganic compounds. Examples of the organic compound are polyaniline derivatives, viologen, metal phthalocyanine, and phenanthroline complexes. Examples of the inorganic compound are tungsten trioxide and indium dioxide. Examples of the electrolyte are liquid electrolytes such as lithium salts and potassium salts, or polymer solid electrolytes.

[0031] The light-adjusting sheet 101 faces the test image display body 11. The test image display body 11 displays a test image toward the light-adjusting sheet 101. The test image display body 11 may be a sheet on which the test image is drawn using slits, a print medium on which the test image is printed, or a device or medium that displays the test image in a photographable manner. The test image display body 11 may bring the light-adjusting sheet 101 and the test image into contact with each other, or a predetermined distance may be provided between the light-adjusting sheet 101 and the test image. When a predetermined distance is provided between the light-adjusting sheet 101 and the test image, the test image display body 11 may display the test image on the light-adjusting sheet 101 via a transparent body 102. When it is required to improve the accuracy of evaluating the blur of the test image caused by the light-adjusting sheet 101, the predetermined distance between the light-adjusting sheet 101 and the test image is preferably 0.05 mm or more and 2.0 mm or less, and more preferably 0.5 mm or more and 1.5 mm or less.

[0032] When the test image display 11 has a slit, the test image display 11 may further include a surface light source 12. The test image display 11 has a black plate shape sandwiched between the light controlling sheet 101 and the surface light source 12. The surface light source 12 irradiates the test image display 11 with surface white light. The test image display 11 irradiates the white light through the slit toward the light controlling sheet 101. As a result, the test image display 11 displays a white linear pattern that follows the shape of the slit as a test image. When uniform brightness is required across the entire test image of the white linear pattern, the white light irradiated by the surface light source 12 is preferably a parallel beam.

[0033] [Characteristic index value calculation system] The condition evaluation system for the light adjusting sheet 101 includes an image generation unit 20 and an index value calculation device 30. The image generation unit 20 includes an imaging unit 21 and a shielding unit 22. The index value calculation device 30 includes an image processing unit 31, an index value calculation unit 32, and an index value determination unit 33. The imaging unit 21 transmits the captured image generated by the imaging unit 21 to the image processing unit 31. The image processing unit 31 is an example of an acquisition unit, and performs image processing on the captured image received by the image processing unit 31. The index value calculation unit 32 calculates a characteristic index value of the captured image from the processing result of the image processing unit 31. The index value determination unit 33 outputs an evaluation result of the light adjusting sheet 101 based on the calculation result of the index value calculation unit 32.

[0034] The photographing unit 21 includes an image sensor and a photographing optical system. The image sensor has photographing elements such as CCDs (Charged Coupled Devices) or CMOSs ​​(Complementary Metal Oxide Semiconductors) arranged two-dimensionally. The photographing optical system focuses light emitted from the test image display medium 11 onto the light receiving surface of the image sensor. The photographing unit 21 generates a photographed image from the light focused on the light receiving surface. The photographed image is data that reproduces a still image of the test image display medium 11 through the light controlling sheet 101. The photographing unit 21 may be a camera mounted on a smartphone or tablet terminal, a surveillance camera installed in various facilities such as commercial facilities or public facilities, or a general camera such as a digital camera.

[0035] The shielding portion 22 assists in reproducing the surrounding environment. The surrounding environment is the environment surrounding the imaging unit 21 that affects the imaging of the imaging unit 21. For example, the shielding portion 22 assists in the test image display 11 and the imaging unit 21 facing each other via the light control sheet 101 and the transparent body 102. The shielding portion 22 assists in maintaining a predetermined distance between the test image display 11 and the imaging unit 21. In this way, the shielding portion 22 assists in reproducing the imaging distance and imaging range. For example, the shielding portion 22 covers the periphery of the test image display 11 and the periphery of the imaging unit 21 with a black member. In this way, the shielding portion 22 assists in reproducing the brightness of the surrounding environment during imaging. Furthermore, when it is required to position the test image display 11 in an area with minimal distortion, the shielding portion 22 may have a function of positioning the center of the imaging range in the image generation unit 20 and the center of the test image display 11. In this case, if it is required to improve the accuracy of evaluating the blur of the test image caused by the light controlling sheet 101, it is preferable that the image generating unit 20 captures the range of the test image display medium 11 at a resolution of 1000 pixels or more.

[0036] Note that, in a surrounding environment where a predetermined captured image can be reproduced from a predetermined test image display medium 11 via a light controlling sheet 101 having predetermined optical properties, the image generating unit 20 may omit the shielding unit 22. For example, when the light controlling sheet 101 is placed in a dark place and the distance between the test image display medium 11 and the capturing unit 21 is fixed to a predetermined value, the image generating unit 20 may omit the shielding unit 22.

[0037] For example, if a predetermined indoor illuminance is obtained in the room where the light controlling sheet 101 is placed and the distance between the test image display 11 and the photographing unit 21 is fixed to a predetermined value, the shielding unit 22 may be omitted. For example, obtaining a predetermined indoor illuminance means that a light with a predetermined illuminance is turned on where the photographing unit 21 is placed.

[0038] For example, if a predetermined outdoor illuminance is obtained outdoors where the light controlling sheet 101 is placed, and the distance between the test image display 11 and the photographing unit 21 is fixed to a predetermined value, the image generating unit 20 may omit the shielding unit 22. Obtaining a predetermined outdoor illuminance means that the amount of solar radiation at the location where the photographing unit 21 is placed is evaluated to be a predetermined amount, such as when the photographing date and time is a predetermined date and time, or when the weather at the time of photographing is fine.

[0039] The environment in which a captured image is generated includes the ambient environment of the imaging unit 21 as described above, as well as the setting environment of the imaging unit 21 itself. The setting environment of the imaging unit 21 includes setting the manual focus distance at the time of shooting to a predetermined value, and setting the aperture value and shutter speed to predetermined values. The ambient environment of the imaging unit 21 and the setting environment of the imaging unit 21 itself do not require dedicated optical equipment such as an integrating sphere or detector, and can be reproduced using general-purpose imaging equipment such as a smartphone or tablet terminal.

[0040] [Characteristic index value] The characteristic index value is the degree of blurring of the test image display body 11 by the light-adjusting sheet 101. The characteristic index value is a measure of the optical characteristics of the light-adjusting sheet 101 at the time of photographing. The characteristic index value is used to evaluate the condition of the light-adjusting sheet 101. The condition evaluation of the light-adjusting sheet 101 may include (i) physical property evaluation, which is an evaluation of whether the light-adjusting sheet 101 has predetermined optical characteristics, i.e., an evaluation of the response of the light-adjusting sheet 101 to light. The condition evaluation of the light-adjusting sheet 101 may include (ii) drive evaluation, which is an evaluation of whether the drive device causes the light-adjusting sheet 101 to achieve a predetermined response, i.e., an evaluation of the drive signal output by the drive device. The drive signal includes the level of the drive voltage and the period of polarity inversion in the drive voltage.

[0041] (i) The physical property evaluation may be used to inspect the light controlling sheet 101 or may be used to analyze the light controlling sheet 101. For example, the sheet inspection may be a determination as to whether the light adjusting sheet 101 is normal. In the abnormality determination, the characteristic index value of the light adjusting sheet 101 being inspected may be compared with the characteristic index value of the light adjusting sheet 101 when the optical characteristics are normal. The sheet inspection may be a determination as to whether the light adjusting sheet 101 has deteriorated. In the deterioration determination, it may be determined whether the deviation between the characteristic index value of the light adjusting sheet 101 being inspected and the previous characteristic index value obtained from the light adjusting sheet 101 is within a predetermined range. The sheet inspection is performed, for example, during the development period, manufacturing period, installation period, or use period of the light adjusting sheet 101.

[0042] In addition, the characteristic index value of the light-adjusting sheet 101 when the optical characteristics are normal may be obtained from an image captured through the light-adjusting sheet 101 that satisfies specified optical characteristics, or may be obtained from a simulation using the specified optical characteristics.

[0043] For example, the sheet analysis may be an analysis related to the optical state of the light controlling sheet 101. In the state analysis, the correlation between the optical properties of the light controlling sheet 101 and the characteristic index value of the light controlling sheet 101 may be used to determine the optical properties of the object to be analyzed based on the characteristic index value of the light controlling sheet 101 to be analyzed. The state analysis is performed, for example, during the development period, manufacturing period, installation period, or use period of the light controlling sheet 101.

[0044] The correlation between the optical properties of the light-adjusting sheet 101 and the characteristic index value of the light-adjusting sheet 101 may be obtained from an image captured through the light-adjusting sheet 101 that satisfies specified optical properties, or may be obtained from a simulation using the specified optical properties.

[0045] (ii) The drive evaluation may be used to correct the drive voltage or to analyze the drive device. For example, the drive correction may be a change in the voltage of the drive signal. In the drive correction, a voltage for obtaining a predetermined optical characteristic may be determined from the characteristic index value of the light controlling sheet 101 to which the drive signal to be corrected is input. The voltage is determined by applying the deviation between the characteristic index value of the light controlling sheet 101 having the predetermined optical characteristic and the characteristic index value of the light controlling sheet 101 to which the drive signal to be corrected is input to the relationship between the deviation in the characteristic index value and the voltage. The drive correction is performed, for example, during the development, manufacturing, installation, or use of the light controlling sheet 101.

[0046] In addition, the relationship between the deviation of the characteristic index value and the voltage may be obtained from an image captured through the light controlling sheet 101 that satisfies predetermined optical characteristics and a drive signal input to the light controlling sheet 101.

[0047] For example, drive analysis may involve using the correlation between the drive signal of the light-adjusting sheet 101 and the characteristic index value of the light-adjusting sheet 101 to understand the characteristics of the drive signal based on the characteristic index value of the light-adjusting sheet 101 being analyzed. The characteristics of the drive signal may be, for example, the voltage of the drive signal or the period of polarity inversion in the drive signal. The characteristics of the drive signal can be understood by applying the characteristic index value of the light-adjusting sheet 101 to which a specified drive signal has been input to the relationship between the characteristic index value and the characteristics of the drive signal.

[0048] The relationship between the characteristic index value and the characteristics of the drive signal may be obtained from an image captured through the light controlling sheet 101 and the characteristics of the drive signal input to the light controlling sheet 101. Examples of optical characteristics that serve as criteria for state evaluation include the following four types (a) to (d).

[0049] (a) The criterion for the condition evaluation may be that the haze is equal to or greater than a predetermined value. A haze equal to or greater than a predetermined value may be a high value that makes it impossible to visually recognize the details of the shielded object through the light controlling sheet 101. A haze equal to or greater than a predetermined value may be a value that makes it possible to visually recognize the details of the shielded object through the light controlling sheet 101.

[0050] (b) The criterion for the condition evaluation may be that the haze is equal to or less than a predetermined value. The haze equal to or less than the predetermined value may be a low value that allows the details of the shielded object to be visually recognized through the light controlling sheet 101. The haze equal to or less than the predetermined value may be a value that prevents the details of the shielded object from being visually recognized through the light controlling sheet 101.

[0051] (c) The criterion for the condition evaluation may be that the clarity is equal to or lower than a predetermined value. The clarity equal to or lower than the predetermined value may be so low that the details of the object to be shielded cannot be visually recognized through the light controlling sheet 101.

[0052] (d) The standard for the condition evaluation may be that the clarity is equal to or greater than a predetermined value. The clarity equal to or greater than a predetermined value may be high enough to allow the details of the object to be visually recognized through the light controlling sheet 101.

[0053] [Index value calculation device 30] The index value calculation device 30 may be a device that executes all of its processes using software, or a device that executes only some of its processes using software. For example, the index value calculation device 30 may include dedicated hardware such as a graphics processing unit (GPU) or application specific integrated circuit (ASIC) that executes some of its processes. The index value calculation device 30 may be configured as one or more processors that operate according to a computer program, one or more dedicated hardware circuits such as ASICs, or a processing circuit that combines these. In the following, an example will be described in which a characteristic index value calculation program is stored in a readable medium that the index value calculation device 30 can read, and the characteristic index value calculation program stored in the readable medium is read and executed to perform all processes. The characteristic index value calculation program includes an index value calculation program and an index value determination program.

[0054] The index value calculation device 30 may be a maintenance device communicatively connected to the photographing unit 21 without a network. The index value calculation device 30 may be a server device communicatively connected to the photographing unit 21 via a network. The index value calculation device 30 may be a device built into a user terminal equipped with the photographing unit 21. The index value calculation device 30 may be, for example, a server device that accepts a condition evaluation request from a user terminal equipped with the photographing unit 21 and receives a photographed image taken through the light controlling sheet 101 from the user terminal.

[0055] The image processing unit 31 is connected to the photographing unit 21 via wired communication or wireless communication. The image processing unit 31 is configured to be able to receive photographed images from the photographing unit 21. The image processing unit 31 acquires the photographed images from the photographing unit 21 and performs image processing on the acquired photographed images to calculate characteristic index values.

[0056] The image processing unit 31 performs [Process 1] grayscaling of the captured image. Grayscaling converts image data in RGB space into image data in YUV space. Grayscaling may use either the median method or the weighted average method. The median method outputs the median value of RGB values. The weighted average method outputs the average value of RGB values ​​weighted by the coefficient of each color. Grayscaling may also use a combination of the weighted average method and correction. The combination of the weighted average method and correction applies gamma correction to the weighted average value of RGB values ​​weighted by the coefficient of each color. Grayscaling may also use either the simple average method or the median method. The simple average method outputs the simple average value of RGB values. The median method outputs the median value of the RGB values.

[0057] The index value calculation unit 32 stores an index value calculation program for calculating the characteristic index value and sample extraction conditions used to execute the index value calculation program. The sample extraction conditions are conditions for extracting a sample group used to calculate the characteristic index value from the distribution of radial vectors. The sample extraction conditions are determined based on the results of tests conducted in advance, etc., so that a sample group suitable for condition evaluation is extracted.

[0058] For example, in (i) physical property evaluation or (ii) drive evaluation, if the evaluation criterion is (a) haze of a predetermined value or more, the sample extraction conditions are conditions for extracting a group of samples from the distribution of radial vectors that are suitable for determining whether or not the haze is (a) a predetermined value or more.

[0059] For example, in (i) physical property evaluation or (ii) drive evaluation, if the evaluation criterion is (b) haze below a predetermined value, the sample extraction conditions are conditions for extracting a group of samples from the distribution of radial vectors that are suitable for determining whether or not the haze is (b) below the predetermined value.

[0060] For example, in (i) physical property evaluation or (ii) drive evaluation, if the evaluation criterion is (c) clarity below a predetermined value, the sample extraction conditions are conditions for extracting a group of samples from the distribution of radial vectors that are suitable for determining whether the clarity is (c) below a predetermined value.

[0061] For example, in (i) physical property evaluation or (ii) drive evaluation, if the evaluation criterion is (d) clarity of a predetermined value or more, the sample extraction conditions are conditions for extracting a group of samples from the distribution of radial vectors that are suitable for determining whether or not the clarity is (d) a predetermined value or more.

[0062] The index value calculation unit 32 uses the image processing results of the captured image and reads and executes an index value calculation program, thereby calculating the degree of blurring of the captured image caused by the light adjusting sheet 101 as a characteristic index value. That is, the index value calculation unit 32 uses the grayscaled image data in [Process 1] and performs a two-dimensional fast Fourier transform in [Process 2]. The index value calculation unit 32 uses the results of the fast Fourier transform and performs frequency analysis of the Fourier transformed image in [Process 3]. The index value calculation unit 32 uses the results of the frequency analysis to calculate a characteristic index value from the radial vector of the sample group.

[0063] [Process 2] A two-dimensional fast Fourier transform calculates the distribution of radial vectors in the two-dimensional Fourier transform image from the grayscaled image data. The radial distribution p(r), which is the distribution of radial vectors, is the sum of the power spectra in a concentric region located at a distance r from the center of the two-dimensional Fourier transform image. The distribution of radial vectors indicates what spatial frequencies of waves are strongly contained in the radial direction in the grayscaled image data, i.e., indicates the periodicity of the shading in the radial direction in the captured image.

[0064] [Process 3] Frequency analysis extracts a group of samples that satisfy the sample extraction conditions from the distribution of radial vectors. Frequency analysis calculates a characteristic index value from the radial vectors of the extracted group of samples. As described above, the sample extraction conditions are conditions for extracting a group of samples to be used in calculating the characteristic index value from the distribution of radial vectors. Frequency analysis calculates the sum of the radial vectors of all samples that satisfy the sample extraction conditions as a sample integrated value SumV. Frequency analysis calculates the characteristic index value using the calculated sample integrated value SumV and a reference value for normalizing the sample integrated value SumV.

[0065] An example of extracting samples in frequency analysis is described below: Figure 2 shows samples extracted from the power spectrum of a Fourier transform image with dots. 2, an example of the sampling condition is that the distance r is within a predetermined range, i.e., the frequency is within a predetermined frequency band. For example, when the evaluation criterion is a high level of haze that makes it impossible to visually recognize the details of the occluded object, i.e., (a) a haze equal to or greater than a predetermined value, an example of the sampling condition is that the distance r is equal to or greater than a sampling threshold rx. An example of the sampling threshold rx is a value that satisfies the following conditions 1 and 2 in the radial distribution:

[0066] [Condition 1] Sample threshold rx > Extraction reference distance rs [Condition 2] Sample threshold energy p(rx) < Extraction reference energy p(rs) × 10% Here, the extraction reference energy p(rs) is, for example, the maximum value p(r)max that indicates the largest energy in the radial distribution p(r). The extraction reference distance rs is the distance r that gives the maximum value p(r)max.

[0067] In a two-dimensional Fourier transform, waves indicating the presence of a shielded object exhibit lower frequencies than waves indicating the details of the shielded object. In the radial distribution p(r), waves indicating the presence of a shielded object have a smaller distance r than waves indicating the details of the shielded object. Thus, within the range of distances r at which the radial distribution p(r) is obtained, the radial distribution p(r) at a relatively small distance r is more likely to indicate the presence of a shielded object and to exhibit the greatest energy. Conversely, the radial distribution p(r) at a relatively large distance r more likely to indicate the visibility of the shielded object through the light controlling sheet 101 in more detail, such as the details of the shielded object and the surface texture of the shielded object.

[0068] As described above, grayscale waves corresponding to the maximum value p(r)max in the grayscaled image data are likely to be waves indicating the presence of an occluded object. On the other hand, grayscale waves corresponding to energy smaller than the maximum value p(r)max in the grayscaled image data are likely to be waves indicating the details of an occluded object. Extracting a sample group based on [Condition 1] and [Condition 2] excludes waves that are likely to indicate the presence of an occluded object from the sample group, thereby making it possible to extract a sample group suitable for evaluating whether the details of the occluded object are not visible to the naked eye.

[0069] As described above, the settings of [Condition 1] and [Condition 2] set a specific radial vector as the extraction reference energy p(rs), thereby excluding from the sample group waves with frequencies lower than the gradation waves corresponding to the specific radial vector. This exclusion extracts samples suitable for evaluating whether or not waves with frequencies higher than the gradation waves corresponding to the specific radial vector are visually recognizable. In other words, the sample extraction conditions are set to narrow the samples to a predetermined frequency band suitable for condition evaluation from the frequency range in which the magnitude of the frequency components is calculated. Frequency analysis calculates the sum of the radial vectors of all samples extracted based on these sample extraction conditions as the sample integrated value SumV (the dotted area in Figure 2). Frequency analysis divides the sample integrated value SumV by a reference value and normalizes it to the reference value to calculate the characteristic index value.

[0070] In addition, when (a) haze above a predetermined value or (c) clarity below a predetermined value is used as the evaluation standard, the reference value may be a sample integrated value SumV obtained from another captured image, or a predetermined value considered to be equivalent thereto. The other captured image may be an image captured in a predetermined production environment without using the light-adjusting sheet 101, or an image captured with the light-adjusting sheet 101 made transparent. In this case, the sample integrated value SumV normalized by the reference value is an example of a first characteristic index value, and the reference value obtained from the image captured with the light-adjusting sheet 101 made transparent is an example of a second characteristic index value. The range of normalized values ​​indicating that the optical characteristics of the light-adjusting sheet 101 are normal is an example of a normal range.

[0071] Furthermore, when (b) haze below a predetermined value or (d) clarity above a predetermined value is adopted as the evaluation standard, the reference value may be the sample integrated value SumV obtained from another captured image, or a predetermined value considered to be equivalent thereto. The other captured image may be an image captured in a predetermined generating environment without using the light controlling sheet 101.

[0072] In any of the cases (a) to (d), whether it is (i) physical property evaluation or (ii) driving evaluation, the reference value may be calculated in advance by the index value calculation device 30 or may be input in advance to the index value calculation device 30.

[0073] The index value determination unit 33 includes an index value determination program for determining the optical state and determination conditions used to execute the index value determination program. The determination conditions are characteristic index values ​​or ranges of characteristic index values ​​that satisfy the evaluation criteria in the state evaluation. The determination conditions may be determined based on the results of tests conducted in advance, or may be input to the index value determination unit 33 in advance. An example of a determination condition is the normal range described above. The index value determination unit 33 applies the calculation results of the index value calculation unit 32 to the determination conditions and outputs the results of the state evaluation of the light controlling sheet 101 based on the determination conditions.

[0074] The index value determination unit 33 may (i) in the physical property evaluation notify an external notification device of the occurrence of an abnormality in the physical property inspection, or may notify an external notification device of the occurrence of deterioration in the deterioration determination. The index value determination unit 33 may (ii) in the drive evaluation notify an external notification device that correction of the drive voltage is unnecessary, or may notify an external notification device that correction of the drive voltage is recommended. In response to an external command, the index value determination unit 33 may transmit the characteristic index value calculated by the index value calculation unit 32 and the determination result using the physical property index value to the user terminal.

[0075] [Test image display 11] Figures 3 and 4 show image example 1, which is an image obtained by photographing a test image of the embodiment, and the magnitude of the radial distribution p(r) obtained from image example 1. Figures 5 and 6 show image example 2, which is an image obtained by photographing a test image of a reference example, and the magnitude of the radial distribution p(r) obtained from image example 2. Figures 7 and 8 show image example 3, which is an image obtained by photographing a test image of another reference example, and the magnitude of the radial distribution p(r) obtained from image example 3. Figures 9 and 10 show image example 4, which is an image obtained by photographing a test image of another reference example, and the magnitude of the radial distribution p(r) obtained from image example 4. Figures 11 and 12 show image example 5, which is an image obtained by photographing a test image of another reference example, and the magnitude of the radial distribution p(r) obtained from image example 5.

[0076] 3, 5, 7, 9, and 11 are examples of images captured through a transparent light controlling sheet 101. The light controlling sheet 101 is a normal type liquid crystal light controlling sheet having a polymer network. The radial distributions p(r) in Figures 4, 6, 8, 10, and 12 are examples of images captured through the light-controlling sheet 101 in a transparent state. The radial distributions p(r) in Figures 4, 6, 8, 10, and 12 also include examples of images captured through the light-controlling sheet 101 in an opaque state. Furthermore, the radial distribution p(r) in Figure 4 includes an example of an image captured through the light-controlling sheet 101 in an intermediate state.

[0077] Each radial distribution p(r) obtained from the captured image is calculated by the following process. First, the image captured by the image capture unit 21 is cropped so that the vertical and horizontal dimensions, which are the captured range of the test image, are 600 cps x 600 cps. Next, the cropped image is compressed so that the vertical and horizontal dimensions are 256 cps x 256 cps. Next, grayscale processing in accordance with the ITU-R Rec BT.601 standard is performed as [Process 1] grayscaling. Furthermore, using the grayscaled image data, [Process 2] two-dimensional fast Fourier transform and [Process 3] frequency analysis are performed, and the radial distribution p(r) is calculated during this process.

[0078] The horizontal axis in each of Figures 4, 6, 8, 10, and 12 represents the frequency corresponding to the distance r. The vertical axis represents the radial distribution p(r) normalized by the maximum value p(r)max, and is shown as intensity. In Figures 4, 6, 8, 10, and 12, the intensity obtained through the light-controlling sheet 101 in the transparent state is shown by a solid line, the intensity obtained through the light-controlling sheet 101 in the opaque state is shown by a two-dot chain line, and the intensity obtained through the light-controlling sheet 101 in a state intermediate between the transparent and opaque states is shown by a thin dashed line. The transparent state, the opaque state, and the intermediate state between the transparent and opaque states were obtained by changing the driving voltage.

[0079] Evaluating the visibility of a blocked object through the light-adjusting sheet 101 is equivalent to evaluating the optical characteristics of the light-adjusting sheet 101. If the radial distribution p(r) at a relatively large distance r follows changes in the optical characteristics of the light-adjusting sheet 101 with high accuracy, the characteristic index value obtained from the radial distribution p(r) will faithfully represent the visibility of the blocked object through the light-adjusting sheet 101. In other words, test images that finely vary the radial distribution p(r) can evaluate the optical characteristics of the light-adjusting sheet 101 with high accuracy among various test images. Test images that more finely vary the radial distribution p(r) finely vary both the radial distribution p(r) at a relatively large distance r and the radial distribution p(r) at a relatively small distance r to follow changes in the optical characteristics of the light-adjusting sheet 101.

[0080] [Photo example 1] As shown in FIG. 3, the test image captured in Image Example 1 is a pattern of white light leaking from linear slits. In Image Example 1, multiple linear slits are geometrically arranged against a black background. The width SL1 of the linear white light (see FIG. 16) is 0.2 mm or more and 0.5 mm or less. The spacing SB1 between adjacent linear white light beams (see FIG. 16) is 2.8 mm or more and 3.0 mm or less.

[0081] The test image of photographed image example 1 is composed of three first straight lines 11A, three second straight lines 11B, and three third straight lines 11C. The first straight lines 11A, second straight lines 11B, and third straight lines 11C are isolated straight lines that do not intersect with each other and are spaced apart from each other.

[0082] The length of the first straight line 11A is shorter than the second straight line 11B and longer than the third straight line 11C. The first straight lines 11A extend in the tangential direction of a first circle inscribed in the three first straight lines 11A. The three first straight lines 11A are equally spaced, one every 120° in the circumferential direction of the first circle.

[0083] The second straight lines 11B extend in the tangential direction of a second circle inscribed in the three second straight lines 11B, and are equally spaced at 120° intervals in the circumferential direction of the second circle. The diameter of the second circle inscribed in the three second straight lines 11B is larger than the diameter of the first circle inscribed in the three first straight lines 11A. Each second straight line 11B is located between adjacent first straight lines 11A in the circumferential direction of the second circle. The angle formed between the normal to the first straight line 11A and the normal to the second straight line 11B is 60°.

[0084] The three third straight lines 11C are located outside the first circle inscribed in the three first straight lines 11A and cross the second circle inscribed in the three second straight lines 11B. Each third straight line 11C is located on a normal to a different first straight line 11A. An extension line passing through each third straight line 11C passes through the center of a different first straight line 11A.

[0085] The center of the first circle inscribed in the three first straight lines 11A is the same as the center of the second circle inscribed in the three second straight lines 11B. The diameter of the first circle inscribed in the three first straight lines 11A is slightly larger than the length of the first straight lines 11A. The diameter of the second circle inscribed in the three second straight lines 11B is approximately twice the diameter of the first circle inscribed in the first straight lines 11A and slightly larger than the length of the second straight lines 11B.

[0086] Fig. 4 shows the dependency of the radial direction distribution p(r) of the captured image example 1 on the optical characteristics of the light controlling sheet 101. That is, Fig. 4 shows the dependency of the radial direction distribution p(r) of the captured image example 1 on the driving voltage.

[0087] As shown in FIG. 4, when the light controlling sheet 101 is in a transparent state, the frequency dependence of the radial distribution p(r) of the captured image example 1 shows the presence of many fine peaks. The many fine peaks tend to have smaller peak values ​​as the frequency increases. Among the samples used to calculate the characteristic index value, the difference in peak intensity values ​​between adjacent peaks is 0.2 or less. The frequency dependence of the radial distribution p(r) of the captured image example 1 shows the presence of broad peaks that extend into a relatively high frequency band as a whole.

[0088] The radial distribution p(r) in the captured image example 1 decreases as the light controlling sheet 101 changes from a transparent state to an opaque state, i.e., as the driving voltage decreases. The degree to which the radial distribution p(r) decreases is small in the relatively low frequency range and large in the relatively high frequency range.

[0089] Thus, when the light-controlling sheet 101 is in a transparent state, the frequency dependence of the radial distribution p(r) of the photographed image example 1 shows the presence of many fine peaks. As the light-controlling sheet 101 changes from a transparent state to an opaque state, the frequency dependence of the radial distribution p(r) gradually decreases, as if the fine peaks are being eliminated one by one. In the radial distribution p(r) of the photographed image example 1, when the light-controlling sheet 101 is in a transparent state, the presence of many peaks is observed, and therefore high resolution is obtained in terms of eliminating the peaks one by one. As a result, the photographed image example 1, in which the radial distribution p(r) at relatively high frequencies is changed more finely to follow changes in the optical properties of the light-controlling sheet 101, can evaluate the optical properties of the light-controlling sheet 101 with higher accuracy among various test images.

[0090] [Photo example 2] As shown in Figure 5, the test image captured in Image Example 2 is a pattern of white light leaking from a linear slit. In Image Example 1, multiple linear slits are geometrically arranged against a black background.

[0091] The test image of the photographed image example 2 is composed of two sets of radial lines, each of which consists of seven fourth straight lines 11D, and two sets of parallel lines, each of which consists of three fifth straight lines 11F. The length of the fourth straight lines 11D is slightly longer than that of the fifth straight lines 11F.

[0092] The ends of the fourth straight lines 11D are located on a single circle. The fourth straight lines 11D extend radially outward from the single circle. The diameter of the single circle on which the ends of the 14 fourth straight lines 11D are located is equal to the length of the fourth straight lines 11D. In each group of radial lines, the seven fourth straight lines 11D are equally spaced, one every 15° in the circumferential direction of the circle. The central angle of the group of radial lines is 90°. Two groups of radial lines are located diagonally with respect to the single circle on which the ends of the 14 fourth straight lines 11D are located.

[0093] Among the group of parallel lines, three fifth straight lines 11F are arranged at equal intervals in one direction. The direction in which the fifth straight lines 11F are arranged is the normal direction to the fifth straight lines 11F. An imaginary line that passes through the center of the fifth straight lines 11F and extends in the normal direction to the fifth straight lines 11F does not pass through the center of the single circle on which the end of the fourth straight line 11D is located. One group of parallel lines is located in one gap between two sets of radial lines in the circumferential direction of the single circle on which the end of the fourth straight line 11D is located. The other group of parallel lines is located in another gap between two sets of radial lines in the circumferential direction of the single circle on which the end of the fourth straight line 11D is located. One group of parallel lines is located diagonally from the other group of parallel lines with respect to the single circle on which the end of the fourth straight line 11D is located. The two sets of parallel lines are asymmetric with respect to the center of the single circle on which the end of the fourth straight line 11D is located.

[0094] Fig. 6 shows the dependency of the radial direction distribution p(r) of the captured image example 2 on the optical characteristics of the light controlling sheet 101. That is, Fig. 4 shows the dependency of the radial direction distribution p(r) of the captured image example 2 on the driving voltage.

[0095] 6, when the light controlling sheet 101 is in a transparent state, the frequency dependence of the radial distribution p(r) of the photographed image example 2 shows the presence of seven peaks that are widely separated from one another. That is, the frequency dependence of the radial distribution p(r) of the photographed image example 2 shows the presence of fewer peaks than that of the photographed image example 1. Furthermore, the spread of the radial distribution p(r) of the photographed image example 2 is lower than that of the photographed image example 1.

[0096] Note that the radial distribution p(r) in captured image example 2 decreases as the light controlling sheet 101 changes from a transparent state to an opaque state, i.e., as the driving voltage decreases. The degree to which the radial distribution p(r) decreases is small in a relatively low frequency range and large in a relatively high frequency range. Among the samples used to calculate the characteristic index value, the difference in peak intensity values ​​between adjacent peaks is slightly greater than 0.2.

[0097] As described above, the radial distribution p(r) of photographed image example 2 is larger when the light-adjusting sheet 101 is in a transparent state than when it is in an opaque state. Based on this tendency, the test image of photographed image example 2 can be used to evaluate the optical characteristics of the light-adjusting sheet 101. However, the frequency dependence of the radial distribution p(r) of photographed image example 2 shows the presence of coarser peaks compared to photographed image example 1. Furthermore, as described above, calculation of the characteristic index value using the test image of photographed image example 1 can make the radial distribution p(r) at relatively high frequencies follow changes in the optical characteristics of the light-adjusting sheet 101 with high sensitivity, thereby enabling the optical characteristics of the light-adjusting sheet 101 to be evaluated with higher accuracy.

[0098] [Photo example 3] 7, the test image captured in Image Example 3 is a pattern of white light leaking from a linear slit. In Image Example 3, multiple linear slits are geometrically arranged against a black background.

[0099] The test image of the photographed image example 3 is composed of six first straight lines 11A, six second straight lines 11B, and six third straight lines 11C. The number of straight lines constituting the photographed image of the photographed image example 3 is twice the number of straight lines in the test image of the photographed image example 1.

[0100] The six first straight lines 11A form two groups of straight lines, each consisting of three first straight lines 11A. The diameter of a circle inscribed with one group of lines is larger than the diameter of a circle inscribed with the other group of lines. The six second straight lines 11B form two groups of straight lines, each consisting of three second straight lines 11B. The diameter of a circle inscribed with one group of lines is larger than the diameter of a circle inscribed with the other group of lines. The six third straight lines 11C form three groups of straight lines, each consisting of two third straight lines 11C that are parallel to each other.

[0101] Fig. 8 is a graph showing the drive voltage dependency of the radial direction distribution p(r) of captured image example 3. That is, Fig. 8 is a graph showing the dependency of the radial direction distribution p(r) of captured image example 3 on the optical characteristics of the light controlling sheet 101.

[0102] 8, when the light controlling sheet 101 is in a transparent state, the frequency dependence of the radial distribution p(r) of the photographed image example 3 shows the presence of seven peaks that are widely separated from one another. That is, the frequency dependence of the radial distribution p(r) of the photographed image example 3 shows the presence of fewer peaks than that of the photographed image example 1. Furthermore, the spread of frequencies in the radial distribution p(r) of the photographed image example 3 is similar to that of the photographed image example 1, but this is due to the peaks being separated from one another.

[0103] Note that the radial distribution p(r) in image example 3 decreases as the light controlling sheet 101 changes from a transparent state to an opaque state, i.e., as the driving voltage decreases. The degree to which the radial distribution p(r) decreases is small in a relatively low frequency range and large in a relatively high frequency range. Among the samples used to calculate the characteristic index value, the difference in peak intensity values ​​between adjacent peaks greatly exceeds 0.2.

[0104] As described above, the radial distribution p(r) of photographed image example 3 is larger when the light-adjusting sheet 101 is in a transparent state than when it is in an opaque state. Based on this tendency, the test image of photographed image example 3 can be used to evaluate the optical characteristics of the light-adjusting sheet 101. However, the frequency dependence of the radial distribution p(r) of photographed image example 3 shows the presence of coarser peaks compared to photographed image examples 1 and 2. Furthermore, as described above, calculation of the characteristic index value using the test image of photographed image example 1 can make the radial distribution p(r) at relatively high frequencies follow changes in the optical characteristics of the light-adjusting sheet 101 with high sensitivity, thereby enabling the optical characteristics of the light-adjusting sheet 101 to be evaluated with higher accuracy.

[0105] [Photo example 4] 9, the test image captured in Image Example 4 is a pattern of white light leaking from a linear slit. In Image Example 4, multiple linear slits are geometrically arranged against a black background.

[0106] 9, the test image of photographed image example 4 is composed of 12 fifth straight lines 11F. The test image of photographed image example 4 is composed of twice the number of parallel lines as the number of parallel lines in the test image of photographed image example 2, and is the same as the photographed image of photographed image example 2 in which the radial lines have been omitted.

[0107] The twelve fifth straight lines 11F are composed of four sets of parallel lines, each set consisting of three fifth straight lines 11F. Of the four sets of parallel lines, two sets of parallel lines are figures obtained by translating and rotating the other two sets of parallel lines. Of the four sets of parallel lines, two sets of parallel lines correspond to the parallel lines in photographed image example 2. The center of a single circle inscribed in the four sets of parallel lines is approximately the same as the center of a single circle circumscribed around the four sets of parallel lines.

[0108] Fig. 10 is a graph showing the drive voltage dependency of the radial direction distribution p(r) of captured image example 4. That is, Fig. 10 is a graph showing the dependency of the radial direction distribution p(r) of captured image example 4 on the optical characteristics of the light controlling sheet 101.

[0109] 10, when the light controlling sheet 101 is in a transparent state, the frequency dependence of the radial distribution p(r) of the photographed image example 4 shows the presence of six sharp peaks that are widely separated from one another. That is, the frequency dependence of the radial distribution p(r) of the photographed image example 4 shows the presence of fewer peaks than those of the photographed image examples 1, 2, and 3. Furthermore, the frequency spread of the radial distribution p(r) of the photographed image example 4 is approximately the same as that of the photographed image example 2.

[0110] Note that the radial distribution p(r) in image example 4 decreases as the light controlling sheet 101 changes from a transparent state to an opaque state, i.e., as the driving voltage decreases. The degree to which the radial distribution p(r) decreases is small in a relatively low frequency range and large in a relatively high frequency range. Among the samples used to calculate the characteristic index value, the difference in peak intensity values ​​between adjacent peaks significantly exceeds 0.2.

[0111] As described above, the radial distribution p(r) of photographed image example 4 is larger when the light-adjusting sheet 101 is in a transparent state than when it is in an opaque state. Based on this tendency, the test image of photographed image example 4 can be used to evaluate the optical characteristics of the light-adjusting sheet 101. However, the frequency dependence of the radial distribution p(r) of photographed image example 4 shows the presence of coarser peaks compared to photographed image examples 1, 2, and 3. Furthermore, as described above, calculation of the characteristic index value using the test image of photographed image example 1 can make the radial distribution p(r) at relatively high frequencies follow changes in the optical characteristics of the light-adjusting sheet 101 with high sensitivity, thereby enabling the optical characteristics of the light-adjusting sheet 101 to be evaluated with higher accuracy.

[0112] [Photo example 5] 11, the test image captured in Image Example 5 is a pattern of white light leaking from a circular hole and five annular slits. In Image Example 5, a circular hole and five annular slits arranged concentrically around the circular hole are arranged against a black background.

[0113] 12 is a graph showing the drive voltage dependency of the radial direction distribution p(r) of captured image example 5. That is, FIG. 12 is a graph showing the dependency of the radial direction distribution p(r) of captured image example 5 on the optical characteristics of the light controlling sheet 101.

[0114] 12, when the light controlling sheet 101 is in a transparent state, the frequency dependence of the radial distribution p(r) of the photographed image example 5 shows the presence of five sharp peaks that are widely separated from one another. That is, the frequency dependence of the radial distribution p(r) of the photographed image example 5 shows the presence of fewer peaks than the photographed image examples 1, 2, 3, and 4. Furthermore, the frequency spread of the radial distribution p(r) of the photographed image example 5 is about the same as that of the photographed image example 2.

[0115] Note that the radial distribution p(r) of captured image example 5 decreases as the light controlling sheet 101 changes from a transparent state to an opaque state, i.e., as the driving voltage decreases. The degree to which the radial distribution p(r) decreases is small in a relatively low frequency range and large in a relatively high frequency range. Among the samples used to calculate the characteristic index value, the difference in peak intensity values ​​between adjacent peaks is a very large value of approximately 0.8.

[0116] As described above, the radial distribution p(r) of photographed image example 5 is larger when the light-adjusting sheet 101 is in a transparent state than when it is in an opaque state. Based on this tendency, the test image of photographed image example 5 can evaluate the optical characteristics of the light-adjusting sheet 101. However, the frequency dependence of the radial distribution p(r) of photographed image example 5 shows the presence of coarser peaks compared to photographed image examples 1, 2, 3, and 4. Furthermore, as described above, calculation of the characteristic index value using the test image of photographed image example 1 can make the radial distribution p(r) at relatively high frequencies follow changes in the optical characteristics of the light-adjusting sheet 101 with high sensitivity, thereby enabling the optical characteristics of the light-adjusting sheet 101 to be evaluated with higher accuracy.

[0117] [Correlation between characteristic index values ​​and haze] As described above, differences in the test images result in different changes in the radial distribution p(r) in response to changes in the optical properties of the light controlling sheet 101. The test image of photographed image example 1 causes the high-frequency radial distribution p(r) to closely track changes in the optical properties of the light controlling sheet 101. Below, we will explain the relationship between the characteristic index value at the shooting point of the light controlling sheet 101 using the test image of photographed image example 1 and the haze measurement value at the shooting point.

[0118] FIG. 13 shows the relationship between the characteristic index value obtained from the radial distribution p(r) of the photographed image example 1 and the haze of the light-controlling sheet 101. In the example shown in FIG. 13, the haze of the light-controlling sheet 101 was changed by changing the voltage level of the drive signal. Furthermore, using the test image of the photographed image example 1, photographed images were obtained for each haze through the light-controlling sheet 101 with different hazes, and then the characteristic index value for each haze was calculated from the radial distribution p(r) of each photographed image. In calculating the characteristic index value, a group of samples satisfying the above-mentioned [Condition 1] and [Condition 2] was extracted in the frequency analysis of [Process 3]. The maximum value p(r)max for each haze was used as the extraction reference energy p(rs) in [Condition 2]. The sum of all radial vectors, including the maximum value p(r)max, in the photographed image obtained through the light-controlling sheet 101 in a transparent state was used as the reference value for normalizing the characteristic index value for each haze. In addition, in FIG. 13, the reference value is shown as 100%, and the ratio of the sample integrated value SumV for each haze to the reference value is shown as the characteristic index value.

[0119] 13, it was found that the characteristic index value increased as the haze of the light-controlling sheet 101 decreased in the range of 2% to 99%. It was also found that the increase in the characteristic index value per unit change in haze was greater than 1 when the haze was 85% or greater, and was less than 1 when the haze was less than 85%.

[0120] Here, highly accurate evaluation of the opacity state of the light-adjusting sheet 101 is highly required when using the light-adjusting sheet 101. For example, the opacity state of the light-adjusting sheet 101 includes a high scattering state in which the details of the shielded object cannot be visually recognized, and a low scattering state in which the details of the shielded object can be visually recognized. The high scattering state and the low scattering state significantly differ in the degree of privacy protection, such as privacy protection that prevents the details of the shielded object from being visually recognized, and privacy protection that allows the details of the shielded object to be visually recognized. The haze range of 85% or more and 100% or less includes the boundary between haze that allows the details of the shielded object to be visually recognized and haze that does not allow the details of the shielded object to be visually recognized.

[0121] As described above, an increase in the characteristic index value per unit change in haze of greater than 1 indicates that the resolution of the opacity of the light-controlling sheet 101 is higher in the characteristic index value than in the haze. In other words, calculation of the characteristic index value using the test image of photographed image example 1 can accurately determine whether the optical state of the light-controlling sheet 101 is opaque enough to allow visual recognition of the details of the blocked object, or opaque enough to prevent visual recognition of the details of the blocked object. In other words, calculation of the characteristic index value using the test image of photographed image example 1 can provide greater accuracy than haze measurement in distinguishing between opacity that allows visual recognition of the details of the blocked object and opacity that prevents visual recognition of the details of the blocked object.

[0122] 13, the change in the characteristic index value relative to a predetermined change in haze was found to be approximately constant in both the first range where the haze was 2% or more and 80% or less and the second range where the haze was 95% or more and 99% or less. Note that the change in the characteristic index value relative to a predetermined change in haze gradually changes between the first and second ranges.

[0123] In this way, the change in the characteristic index value relative to a predetermined change in haze exhibits different linearities in the first and second ranges. Having different linearities makes it possible to determine, for example, whether the optical state of the light controlling sheet 101 falls within a haze range of 2% to 80% or a haze range of 95% to 99% based on the change in the characteristic index value relative to a change in the driving voltage. Furthermore, the fact that the change in the characteristic index value relative to a predetermined change in haze is linear over a wide range facilitates estimation of haze based on the characteristic index value and increases the accuracy of the estimated haze.

[0124] [Correlation between characteristic index values ​​and dimming response] As described above, the drive signal that drives the light controlling sheet 101 is input to a terminal provided on the light controlling sheet 101. The greater the distance between the shooting point and the terminal, the greater the deviation of the voltage at the shooting point on the light controlling sheet 101 from the voltage at the terminal. The deviation in voltage between the shooting point and the terminal causes variation in the optical state inside the light controlling sheet 101. Below, we will explain the response of the characteristic index value to voltage using the test image of photographed image example 1, and the response of the optical state inside the light controlling sheet 101 to voltage.

[0125] 14, the left edge of the light controlling sheet 101 is provided with a terminal 101P to which a drive signal is input. The light controlling sheet 101 is provided with a first shooting point 101A and a second shooting point 101B. The first shooting point 101A and the second shooting point 101B are points at which test images are captured through the light controlling sheet 101, respectively.

[0126] The length of the light controlling sheet 101 is 1500 mm. The width W1 of the light controlling sheet 101 is 300 mm. The width LP of the terminal 101P in the left-right direction is 10 mm. The length L1 in the left-right direction between the terminal 101P and the first shooting point 101A is 100 mm. The length L2 in the left-right direction between the terminal 101P and the second shooting point 101B is 1400 mm. For example, when a voltage of 20 V is applied to the terminal 101P, a voltage of 17.5 V, which is lower than the voltage applied to the terminal 101P at the left end of the light controlling sheet 101, is applied to the terminal at the right end of the light controlling sheet 101. For example, when a voltage of 30 V is applied to the terminal 101P, a voltage of 26.2 V, which is lower than the voltage applied to the terminal 101P at the left end of the light controlling sheet 101, is applied to the terminal at the right end of the light controlling sheet 101. That is, the voltage applied to the light controlling sheet 101 deviates more from the voltage at the terminal 101P as the distance from the terminal 101P increases.

[0127] FIG. 15 shows the voltage dependence of the characteristic index values ​​at the first photographing point 101A and the second photographing point 101B, as well as the voltage dependence of the clarity, total light transmittance, and haze at the center in the horizontal direction of the light controlling sheet 101. Note that the example shown in FIG. 15, like the example shown in FIG. 13, shows the characteristic index values ​​obtained from the radial distribution p(r) of photographed image example 1. In this case, in calculating the characteristic index values, a group of samples satisfying the above-mentioned [Condition 1] and [Condition 2] was extracted in the frequency analysis of [Process 3]. The maximum value p(r)max for each voltage was used as the extraction reference energy p(rs) in [Condition 2]. The sum of all radial vectors, including the maximum value p(r)max, in the photographed image obtained through the light controlling sheet 101 in the transparent state was used as the reference value for normalizing the characteristic index values ​​for each voltage. In FIG. 15, the reference value is shown as 100%, and the ratio of the sample integrated value SumV for each voltage to the reference value is shown as the characteristic index value.

[0128] As shown in FIG. 15, as the voltage of the drive signal increases from 0V to 10V, the clarity of the light controlling sheet 101 increases sharply from 35% to 90%. As the voltage of the drive signal increases from 10V to 20V, the clarity of the light controlling sheet 101 gradually saturates from 90% to 99%. Furthermore, as the voltage of the drive signal increases from 10V to 20V, the total light transmittance of the light controlling sheet 101 increases sharply from 5% to 75%. As the voltage of the drive signal increases from 20V to 30V, the total light transmittance of the light controlling sheet 101 gradually saturates from 75% to 85%. Furthermore, as the voltage of the drive signal increases from 10V to 20V, the haze of the light controlling sheet 101 decreases sharply from 95% to 15%. As the voltage of the drive signal increases from 20V to 30V, the haze of the light controlling sheet 101 gradually saturates from 15% to 5%.

[0129] Similar to the change in haze, as the voltage of the drive signal increases from 10V to 20V, the characteristic index value of the first imaged point 101A drops sharply from 95% to 15%. As the voltage of the drive signal increases from 20V to 30V, the characteristic index value of the first imaged point 101A gradually saturates from 15% to 5%. On the other hand, as the voltage of the drive signal increases from 10V to 20V, the characteristic index value of the second imaged point 101B drops sharply from 95% to 20%. Then, as the voltage of the drive signal increases from 20V to 30V, the characteristic index value of the second imaged point 101B gradually saturates from 20% to 5%.

[0130] Thus, the difference between the characteristic index value at the first imaging point 101A and the characteristic index value at the second imaging point 101B is observed between the high saturated value of the characteristic index value and the low saturated value of the characteristic index value. In other words, calculating the characteristic index value in a transient state at an imaging point a predetermined distance away from the terminal 101P makes it possible to evaluate the degree of deviation in voltage between the imaging point and the terminal 101P.

[0131] [Line width of test image] As shown in FIG. 16, a test image that can evaluate the optical properties of the light-controlling sheet 101 with higher accuracy is a geometric pattern composed of three first straight lines 11A, three second straight lines 11B, and three third straight lines 11C. The width SL1 of each line that makes up the geometric pattern is preferably, for example, 0.2 mm to 0.7 mm, and more preferably 0.2 mm to 0.5 mm. The spacing SB1 between adjacent lines in the geometric pattern is preferably, for example, 2.5 mm to 3.5 mm, and more preferably 2.8 mm to 3.0 mm. If the width SL1 of the lines is 0.2 mm to 0.7 mm, the clarity of the image captured through the light-controlling sheet 101 is more suitable for evaluating the light-controlling sheet 101. If the distance SB1 between adjacent lines is 2.5 mm or more and 3.5 mm or less, the degree of overlap between the blur in the image of one line and the blur in the image of another line adjacent to that line is more suitable for evaluating the light controlling sheet 101. The geometric pattern may be composed of a black background and white lines, or may be composed of a white background and black lines.

[0132] Figure 17 shows an example of the relationship between the width SL1 of the straight line in the test image shown in Figure 16 and the brightness of each pixel in an image captured through the light-adjusting sheet 101. Figure 17 shows a straight line in an image captured using a general-purpose capture function, with a camera film sensitivity of ISO 400, an aperture value of F8, a white balance of K5200, and an image size of 3648 x 2432. In Figure 17, the brightness of each pixel aligned along the width of the straight line is shown as the brightness of the pixel number, starting from the first pixel. The width of the real image represented by each pixel in the captured image is 20 μm. The solid line in Figure 17 represents values ​​obtained from an image captured through the light-adjusting sheet 101 in a transparent state. The light-adjusting sheet 101 in a transparent state has 99% clarity and is obtained by setting the drive signal voltage to 25 V. The dashed line in Figure 17 represents values ​​obtained from an image captured through the light-adjusting sheet 101 in an opaque state. The opaque state of the light controlling sheet 101 is obtained by gradually decreasing the clarity to 35% and gradually decreasing the voltage of the drive signal to 0V.

[0133] Figure 18 shows the relationship between the clarity of the light-adjusting sheet 101 and the blur of the pixel number, with the brightness of the pixel with the pixel number "136" and the brightness of the pixel with the pixel number "146" in Figure 17 being the blur of each pixel number. The pixel with the pixel number "136" and the pixel with the pixel number "146" indicate the vicinity of the end of a straight line in an image captured through the light-adjusting sheet 101 in a transparent state.

[0134] 17, in an image captured through the light controlling sheet 101 in a transparent state, the width SL1 of the line corresponds to 0.3 mm, which is the size indicated by 15 pixels. On the other hand, in an image captured through the light controlling sheet 101 in an opaque state, the width SD1 of the line corresponds to 3.3 mm, which is the size indicated by 165 pixels.

[0135] As shown in Figure 18, the area near the end of a straight line in an image taken through the light controlling sheet 101 in a transparent state begins to blur sharply as the clarity drops from 99% to 70%. On the other hand, the blur near the end of a straight line in an image taken through the light controlling sheet 101 in a transparent state becomes more gradual as the clarity drops from 70% to 35%. The blur of a pixel with a pixel count of "136" and the blur of a pixel with a pixel count of "146" are recognized as different values ​​across the entire clarity range from 35% to 99%.

[0136] Thus, a line width SL1 of 0.3 mm accurately indicates the blur of images captured through the light controlling sheet 101 in each optical state, and is therefore suitable for evaluating the light controlling sheet 101. Furthermore, a spacing SB1 between adjacent lines of 3.3 mm reduces the degree of overlap between the blur in the image of one line and the blur in the images of other lines adjacent to that line to a level that allows each line to be distinguished, and is therefore suitable for evaluating the light controlling sheet 101.

[0137] According to the above embodiment, the following effects can be obtained. (1) The test images are captured using general-purpose imaging devices such as smartphones and tablet devices, rather than dedicated optical devices such as integrating spheres. The magnitude of the radial distribution p(r) in a specific frequency band tends to increase as the haze of the light controlling sheet 101 increases, and is easily synchronized with the haze change of the light controlling sheet 101, making it possible to diversify the characteristic indices that represent the optical properties of the light controlling sheet 101.

[0138] (2) Furthermore, since the test image is composed of three first straight lines 11A, three second straight lines 11B, and three third straight lines 11C, the optical characteristics of the light controlling sheet 101 can be evaluated with high accuracy.

[0139] (3) The second lines 11B are positioned between the adjacent first lines 11A so that the bisector of the angle formed by the adjacent first lines 11A in the circumferential direction of the second circle passes through the center of the second lines 11B in the direction in which the second lines 11B extend. In this case, the effectiveness of improving the accuracy of evaluation of optical characteristics that depends on the relative positions of the first lines 11A and the second lines 11B is enhanced.

[0140] (4) The first straight line 11A is longer than the third straight line 11C and shorter than the diameter of the first circle. The second straight line 11B is longer than the diameter of the first circle and shorter than the diameter of the second circle. The third straight line 11C is longer than the radius of the first circle. In this case, the effectiveness of improving the evaluation accuracy of the optical characteristics, which depends on the length of each straight line, is increased.

[0141] (5) The diameter of the first circle is between ⅓ and ½ of the diameter of the second circle. In this case, the accuracy of evaluation of the optical characteristics that depends on the relative positions of the first straight line 11A and the second straight line 11B is improved.

[0142] (6) The distance SB1 between adjacent lines in the test image is 2 mm or more and 4 mm or less. In this case, the accuracy of the evaluation of optical characteristics that depends on the distance SB1 between the lines constituting the test image is improved.

[0143] (7) The width SL1 of the first straight line 11A is equal to the width SL1 of the second straight line 11B, which is equal to the width SL1 of the third straight line 11C. The width SL1 of each straight line is 0.2 mm or more and 1 mm or less. This increases the effectiveness of improving the accuracy of evaluation of optical characteristics that depends on the difference in width SL1 between the straight lines that make up the test image.

[0144] (8) The range of characteristic index values ​​when the optical characteristics of the light adjusting sheet 101 are normal is within the normal range, and when the characteristic index value calculated using the captured image is within the normal range, the optical characteristics of the light adjusting sheet 101 are determined to be normal. In this case, it can be determined from the captured image of the test image that the optical characteristics of the light adjusting sheet 101 are normal.

[0145] The above embodiment can be modified as follows. The characteristic index value is not limited to a value obtained by normalizing the sample integrated value SumV by a reference value, but may be, for example, the sample integrated value SumV itself. Note that if the characteristic index value when the light controlling sheet 101 is transparent is calculated and the other characteristic index values ​​are normalized using this characteristic index value as a reference value, errors in the characteristic index value due to differences in lighting during shooting and differences in test images can be reduced.

[0146] The index value calculation device 30 may include an output unit that outputs the calculated characteristic index value by display or sound. In this case, processes that use the characteristic index value, such as inspection of the light controlling sheet 101, voltage correction, and deterioration determination, may be performed by another device configured to input the characteristic index value from an operation unit or the like.

[0147] [Test image] The length of the first straight line 11A may be equal to or longer than the length of the second straight line 11B. The length of the first straight line 11A may be equal to or longer than the length of the third straight line 11C. The length of the second straight line 11B may be equal to or longer than the length of the third straight line 11C. The lengths of the first straight line 11A, the second straight line 11B, and the third straight line 11C may be any lengths that do not intersect with each other and are separated and isolated from each other.

[0148] The direction in which the first straight line 11A extends may be a direction different from the tangent direction at the point where the first straight line 11A passes through the first circle, as long as the first straight line 11A is aligned in the circumferential direction of the first circle. In this case, the first circle is not an inscribed circle of the first straight line 11A, but a circle that intersects with the first straight line 11A and has the rotation center of the first straight line 11A as its center.

[0149] The direction in which the second straight line 11B extends may be a direction different from the tangent direction at the point where the second straight line 11B passes through the second circle, as long as the second straight line 11B is aligned in the circumferential direction of the second circle. In this case, the second circle is not an inscribed circle of the second straight line 11B, but a circle that surrounds the first circle and intersects with the second straight line 11B. Note that the second circle may be a circle that surrounds the first circle, and may be concentric with the first circle or may have a center different from the center of the first circle.

[0150] The direction in which the third straight line 11C extends may be a direction different from the normal direction of the first straight line 11A, as long as the third straight line 11C is aligned in the circumferential direction of the third circle. In this case, the third circle is a circle that surrounds the first circle, and may be an inscribed circle of the third straight line 11C, or a circle that intersects with the third straight line 11C. Note that the third circle may be any circle that surrounds the first circle, and may be concentric with the first circle, may have a center different from the center of the first circle, or may be concentric with the second circle, or may have a center different from the center of the second circle. Furthermore, the third circle may be the same as the second circle, or may be different from the second circle.

[0151] Each second straight line 11B may be located in a position facing a gap of the first straight line 11A in the radial direction of the first circle, and may also face the first straight line 11A, or may face only the gap of the first straight line 11A.

[0152] Each third straight line 11C may be located in a position opposite the first straight line 11A in the radial direction of the first circle, and may also be opposite the gap of the first straight line 11A, or may be opposite only the first straight line 11A.

[0153] The number of first straight lines 11A may be different from the number of second straight lines 11B and the number of third straight lines 11C, and may be two, four or more. The number of second straight lines 11B may be different from the number of first straight lines 11A and the number of third straight lines 11C, and may be two, four or more. The number of third straight lines 11C may be different from the number of first straight lines 11A and the number of second straight lines 11B, and may be two, four or more. [Explanation of symbols]

[0154] LP, SD1, SL1...Width SB1…Spacing SumV: Sample sum rx...sample threshold rs…Extraction reference distance 11...Test image display body 11A…1st straight line 11B…Second straight line 11C...Third straight line 11D…4th straight line 11F…5th straight line 12…Surface light source 21...Photography Department 22...Shielding part 30...Index value calculation device 31...Image processing unit 32...Index value calculation unit 33...Index value determination unit 101...Light-adjusting sheet 102...transparent body

Claims

1. A test image display device that displays a test image used to calculate a characteristic index value that represents the optical characteristics of a light controlling sheet, the image of the test image photographed through the light-adjusting sheet is a photographed image, the characteristic index value indicates the magnitude of a radial direction distribution in a predetermined frequency band obtained by a two-dimensional Fourier transform using the captured image, The test image is The line is composed of a plurality of straight lines, each of which is spaced apart from the other straight lines, and an extension of each straight line intersects with an extension of another straight line adjacent to the straight line; The plurality of straight lines are a plurality of first straight lines arranged at intervals in a circumferential direction of a first circle, each of the first straight lines extending in a direction different from a radial direction of the first circle; a plurality of second straight lines arranged at intervals in a circumferential direction of a second circle surrounding the first circle, each second straight line extending in a direction different from a radial direction of the second circle; a plurality of third straight lines arranged at intervals in the circumferential direction of a third circle surrounding the first circle; Equipped with Each second straight line faces a gap of the first straight line in the radial direction of the first circle, each third straight line faces the first straight line in the radial direction of the first circle; The plurality of straight lines are three first straight lines equally spaced on the first circle; three second straight lines equally spaced on the second circle; and three third straight lines equally spaced on the third circle. Test image display body.

2. The third straight line is positioned on a normal line to the first straight line. The test image display according to claim 1 .

3. The second straight lines are arranged to face each other in a gap between the first straight lines adjacent to each other in the circumferential direction of the first circle so that a bisector of an angle formed by the first straight lines adjacent to each other in the circumferential direction of the first circle passes through the center of the second straight line in the direction in which the second straight line extends.

3. The test image display according to claim 1 or 2.

4. the first straight line is longer than the third straight line and shorter than a diameter of the first circle; the second straight line is longer than the diameter of the first circle and shorter than the diameter of the second circle; The third straight line is longer than the radius of the first circle. The test image display according to claim 1 .

5. The diameter of the first circle is equal to or greater than 1 / 3 and equal to or less than 1 / 2 of the diameter of the second circle. The test image display according to claim 1 .

6. The distance between adjacent straight lines among the plurality of straight lines is 2 mm or more and 4 mm or less. The test image display according to claim 1 .

7. The width of the first straight line is equal to the width of the second straight line, The width of the second straight line is equal to the width of the third straight line. The test image display according to claim 1 .

8. The width of the straight line is 0.2 mm or more and 1 mm or less. The test image display according to any one of claims 1 to 7.

9. A characteristic index value calculation system for calculating a characteristic index value representing an optical characteristic of a light controlling sheet, an acquisition unit that acquires a photographed image of a test image in a predetermined environment photographed through the light-adjusting sheet; a calculation unit that calculates the characteristic index value indicating the magnitude of a radial direction distribution in a predetermined frequency band by a two-dimensional Fourier transform using the captured image acquired by the acquisition unit, The test image is The line is composed of a plurality of straight lines, each of which is spaced apart from the other straight lines, and an extension of each straight line intersects with an extension of another straight line adjacent to the straight line; The plurality of straight lines are a plurality of first straight lines arranged at intervals in a circumferential direction of a first circle, each of the first straight lines extending in a direction different from a radial direction of the first circle; a plurality of second straight lines arranged at intervals in a circumferential direction of a second circle surrounding the first circle, each second straight line extending in a direction different from a radial direction of the second circle; a plurality of third straight lines arranged at intervals in the circumferential direction of a third circle surrounding the first circle; Equipped with Each second straight line faces a gap of the first straight line in the radial direction of the first circle, each third straight line faces the first straight line in the radial direction of the first circle; The plurality of straight lines are three first straight lines equally spaced on the first circle; three second straight lines equally spaced on the second circle; and three third straight lines equally spaced on the third circle. Characteristic index value calculation system.

10. the characteristic index value calculated using the captured image taken through the transparent light-adjusting sheet is a first characteristic index value, and the characteristic index value calculated using the captured image taken through the opaque light-adjusting sheet is a second characteristic index value, Further provided is a determination unit that determines that the optical characteristics of the light controlling sheet are normal when a value obtained by normalizing the second characteristic index value by the first characteristic index value is within a normal range. The characteristic index value calculation system according to claim 9 .

11. A characteristic index value calculation method for calculating a characteristic index value representing an optical characteristic of a light controlling sheet, Obtaining a photographed image of a test image in a predetermined environment photographed through the light-adjusting sheet; calculating the characteristic index value indicating the magnitude of radial direction distribution in a predetermined frequency band by two-dimensional Fourier transform using the captured image, The test image is The line is composed of a plurality of straight lines, each of which is spaced apart from the other straight lines, and an extension of each straight line intersects with an extension of another straight line adjacent to the straight line; The plurality of straight lines are a plurality of first straight lines arranged at intervals in a circumferential direction of a first circle, each of the first straight lines extending in a direction different from a radial direction of the first circle; a plurality of second straight lines arranged at intervals in a circumferential direction of a second circle surrounding the first circle, each second straight line extending in a direction different from a radial direction of the second circle; a plurality of third straight lines arranged at intervals in the circumferential direction of a third circle surrounding the first circle; Equipped with Each second straight line faces a gap of the first straight line in the radial direction of the first circle, each third straight line faces the first straight line in the radial direction of the first circle; The plurality of straight lines are three first straight lines equally spaced on the first circle; three second straight lines equally spaced on the second circle; and three third straight lines equally spaced on the third circle. Characteristic index value calculation method.

12. A characteristic index value calculation method for calculating a characteristic index value representing an optical characteristic of a light controlling sheet, Obtaining a photographed image of a test image in a predetermined environment photographed through the light-adjusting sheet; calculating the characteristic index value indicating the magnitude of radial direction distribution in a predetermined frequency band by two-dimensional Fourier transform using the captured image, The test image is The line is composed of a plurality of straight lines, each of which is spaced apart from the other straight lines, and an extension of each straight line intersects with an extension of another straight line adjacent to the straight line, and When the intensity of the radial direction distribution is normalized with the maximum value of the intensity in the radial direction distribution set to 1, the difference in peak intensity values ​​between adjacent peaks in the predetermined frequency band is 0.2 or less. Characteristic index value calculation method.

13. the characteristic index value calculated using the captured image taken through the transparent light-adjusting sheet is a first characteristic index value, and the characteristic index value calculated using the captured image taken through the opaque light-adjusting sheet is a second characteristic index value, The method further includes determining that the optical characteristics of the light controlling sheet are normal when a value obtained by normalizing the second characteristic index value by the first characteristic index value is within a normal range. The characteristic index value calculation method according to claim 11 or 12.

Images