Coating material for measures against photosensitivity and cataract, light transmissive material, window, and lighting apparatus

Abstract

A light transmissive material according to one embodiment is coated with a coating agent having a predetermined filter characteristic. The light transmissive material has a transmittance of less than 65% in a range of 400-480 nm, and has a characteristic that the convolution integral in a wavelength range of 400-480 nm of the predetermined filter characteristic and the absorption spectrum of a human blue cone cell is cut in a range of 40% or more and 80% or less from the convolution integral in said wavelength range of a reference filter characteristic having a transmittance of 100% and said absorption spectrum.

Description

Coating materials for preventing photosensitivity and cataracts, light-transmitting materials, windows and lighting fixtures

[0001] The present invention relates to technologies for coating materials for preventing photosensitivity and cataracts, light-transmitting materials, windows, and lighting fixtures.

[0002] Techniques for filtering specific wavelengths of light are known. For example, Patent Document 1 discloses a high-performance selective optical wavelength filtering system that features a selective optical wavelength filter that selectively blocks 5 to 50% of light at all wavelengths within a wavelength range of 400 to 500 nm.

[0003] Patent No. 5917622

[0004] The invention of Patent Document 1 merely selectively blocks 5 to 50% of light at all wavelengths within the wavelength range of 400 to 500 nm, and does not take into consideration the characteristics of cone cells, which represent the function of humans in sensing light.

[0005] In view of the above background, the present invention provides a light-transmitting material having filter characteristics for providing an environment suited to the visual characteristics of a user (e.g., a healthy person or a patient with photosensitivity). Specifically, the present invention provides a light-transmitting material having filter characteristics that take into account the characteristics of human cone cells.

[0006] One aspect of the present disclosure provides a light-transmitting material coated with a coating agent having predetermined filter characteristics, wherein the light-transmitting material has a transmittance of less than 65% in the range of 400 to 480 nm, and wherein the convolution integral of the predetermined filter characteristics and the absorption spectrum of human blue cone cells in the wavelength band of 400 to 480 nm is cut by 40% or more and 80% or less of the convolution integral of the absorption spectrum in that wavelength band with a reference filter characteristic of 100% transmittance.

[0007] According to the present invention, it is possible to provide a light-transmitting material having filter characteristics that provide an environment suited to the visual characteristics of a user (e.g., a healthy person or a patient with photosensitivity).It is also possible to provide a light-transmitting material having filter characteristics that take into account the characteristics of human cone cells.

[0008] 1 is a diagram illustrating an overview of light sensitivity. 2 is a diagram illustrating the three elements of vision. 3 is a graph illustrating the light absorption spectrum in human cone cells. 4 is a graph illustrating the light absorption spectrum in blue cone cells. 5 is a diagram illustrating the exterior of a building including a light-transmitting material. 6 is a diagram illustrating the configuration of a light-transmitting material. 7 is a graph illustrating the light transmittance in a reference filter characteristic of 100% transmittance. 8 is a graph illustrating the light absorption spectrum in human blue cone cells. 9 is a table illustrating the convolution integral in the reference filter characteristic of 100% transmittance. 10 is a photograph of a prepared sample. 11 is a graph illustrating the light transmittance in a light-transmitting material. 12 is a table illustrating the convolution integral in the filter characteristic of a light-transmitting material. 13 is a graph illustrating the light transmittance in a light-transmitting material with a heat-shielding function. 14 is a table illustrating the convolution integral in the filter characteristic of a light-transmitting material with a heat-shielding function. 15 is a table illustrating the cut rate by convolution with the absorption spectrum of green cone cells in a light-transmitting material with a heat-shielding function. 10 is a table illustrating the cut rate of a light-transmitting material having a heat-shielding function, calculated by convolution with the absorption spectrum of red cone cells.

[0009] 1. Overview Figure 1 is a diagram illustrating an overview of photosensitivity. Photosensitivity (commonly known as Irlen syndrome) is a visual perception disorder that causes hypersensitivity to light, such as sunlight or fluorescent light, resulting in symptoms such as distorted, difficult to see, or moving characters on printed materials (known as "photophobia"). Additionally, photophobia can cause secondary disorders such as headaches and eye strain. Figure 1 schematically illustrates how a photosensitive patient sees text (or characters) compared to a healthy individual. In this example, a photosensitive patient may experience difficulty reading text due to blurred or difficult-to-read text, overlapping characters, or characters shaking while reading.

[0010] Compared to broader eye diseases such as cataracts and glaucoma, research on photosensitivity is still relatively new and less widely recognized. For example, in Europe and the United States, surveys and research have estimated the prevalence of photosensitivity at 22-33%, while in Japan, surveys and research have estimated the prevalence at approximately 6-8%. The difference in prevalence between Europe and the United States and Japan may be due to factors such as the survey subjects, survey conditions, and survey perspectives, as well as racial differences. However, the causal relationship between photosensitivity and race has not yet been determined. Therefore, the number of photosensitivity patients in Japan may potentially include a prevalence of approximately 20-30%, similar to that in Western countries. This may be a disorder familiar to both Westerners and Japanese people.

[0011] Unlike the aforementioned diseases such as cataracts and glaucoma, which are caused by acquired factors such as aging, photosensitivity is a disorder resulting from the light sensitivity of an individual's eyes. Therefore, the severity of symptoms often depends on the individual's innate eye function, and medical treatments such as surgery or procedures are not necessarily optimal. Rather, appropriate treatment requires an engineering approach that addresses the light itself. Here, we explain the mechanism by which the human eye sees.

[0012] FIG. 2 is a diagram illustrating the three elements of vision. Some studies classify the three elements of vision into visual acuity, color vision, and brightness. First, visual acuity refers to the (quantified) function of recognizing and grasping the existence and shape of an object in space, for example. Second, color vision refers to the function of recognizing and distinguishing hues, i.e., the classification of colors assigned to each spectrum (or wavelength band) of light. Third, brightness refers to the intensity of light emitted from an object, and in particular, in this case, refers to the function of the human eye perceiving the brightness (or luminance) of each wavelength.

[0013] Of the three elements of vision, there are known methods for measuring the intensity of vision through visual acuity tests, but knowledge about color vision and brightness is still limited. However, recent research has pointed out that in patients with photosensitivity, there is a particular relationship with the ability to perceive "brightness," or light sensitivity. Here, we will explain the mechanism by which brightness is perceived using human cone cells. Cone cells are a type of photoreceptor cell that controls visual perception from the human eye to the nerves and brain, and are responsible for absorbing external light stimuli that pass through the human retina and converting them into electrical signals. Here, we will explain in detail human cone cells and light sensitivity.

[0014] FIG. 3A is a graph illustrating the light absorption spectrum of human cone cells. In this example, the graph in FIG. 3A shows an example of the light absorption spectrum of cone cells and rod cells, with the vertical axis representing absorbance and the horizontal axis representing the wavelength of light. Cone cells function in bright light, and there are multiple cone cells with different light absorption wavelength characteristics. S, M, and L in FIG. 3A represent the absorption spectra of three cone cells (e.g., S cone cells, M cone cells, and L cone cells), respectively. S cone cells, M cone cells, and L cone cells are cells that respond to blue, green, and red light, respectively. Rod cells, like cone cells, are a type of photoreceptor cell. Rod cells function in the dark and have a single absorption characteristic. R in FIG. 3A represents the absorption spectrum of rod cells.

[0015] Regarding the light absorption spectrum of human cone cells, the following document discloses the light absorption spectrum of cone cells and rod cells in the human retina (see Fig. 2 in the document): JK Bowmaker and HJ Dartnall, "Visual pigments of rods and cones in a human retina," J Physiol (London), vol. 298, pp. 501-511, 1980.

[0016] The graph in Figure 3A shows an example of the light absorption spectrum of cone cells in an average human (or a healthy individual), but the light absorption characteristics vary from person to person. For example, in the case of a person with so-called color vision deficiency, such as color blindness or color weakness, an abnormality is observed in the absorption spectrum of one of the three cone cells (e.g., the absorbance is weaker or stronger than that of a healthy individual). Here, in the case of a patient with photosensitivity, there is a theory that the sensitivity of S cone cells (also called "blue cone cells"), which respond particularly to blue light, differs from that of a healthy individual, which is a factor that causes visual perception disorders such as photophobia, and research is ongoing. Here, blue cone cells will be described.

[0017] FIG. 3B is a graph illustrating the light absorption spectrum in blue cone cells. In this example, the graph in FIG. 3B is a graph in which only the light absorption spectrum in blue cone cells has been extracted from the graph in FIG. 3A. In this example, the light absorption spectrum in blue cone cells has relatively high absorbance in the wavelength range of 380 to 500 nm. Furthermore, a spectral peak appears at a wavelength around 430 nm. Note that the absorbance on the vertical axis in the graphs in FIGS. 3A and 3B is expressed as a percentage of the absorbance of light at each wavelength absorbed by each cone cell, normalized by the maximum absorbance.

[0018] Here, we will explain countermeasures for photosensitivity. In the case of photosensitivity, it is believed that adjusting the light sensitivity of blue cone cells is particularly important. Patients with photosensitivity have a different sensitivity to light containing wavelengths of 380 to 500 nm, which is contained in sunlight (or fluorescent light, etc.), than healthy individuals, and are therefore affected by this sensitivity, which can cause them to perceive any object as being too dazzling. As a result, for example, parts of text printed on white paper become blurred and difficult to read, characters overlap, or characters appear to be shaking. Based on this knowledge, it is believed that the effects of photosensitivity can be alleviated by adjusting the light containing blue wavelengths that enters the eyes of patients with photosensitivity. Next, the configuration of the present invention will be described in detail.

[0019] 2. Configuration 2-1. Light-Transmitting Material FIG. 4A is a diagram illustrating the exterior of a building including a light-transmitting material according to one embodiment. FIG. 4A shows a cross-section of a building, such as a school building. In this example, the light-transmitting material 1 represents a material with a filtering function that transmits or blocks specific wavelengths of sunlight, for example. In this example, the light-transmitting material 1 is used in the windows of a classroom, for example. In this example, the users are students in the classroom. Here, because the light-transmitting material 1 has a light-filtering function, it can alleviate symptoms such as photophobia even if a child with photosensitivity is among the users. On the other hand, in a classroom, where multiple students gather to study, a certain level of brightness must be maintained even for children who are not photosensitive. Therefore, the present invention aims to provide a light-transmitting material that provides a brightness environment in which children with a wide variety of brightness sensitivities, regardless of whether they have photosensitivity, can coexist in one place.

[0020] FIG. 4B is a diagram illustrating the cross-sectional structure of a light-transmitting material. In this example, FIG. 4B shows a cross section of the light-transmitting material 1 cut in the thickness direction. In this example, the light-transmitting material 1 includes a substrate 10 and a coating layer 11. In this example, the substrate 10 is formed of a light-transmitting material such as glass, polycarbonate, or acrylic. It is preferable that the substrate 10 does not transmit or absorb light of a specific wavelength in the visible light region, but rather has as flat a light transmission characteristic (or light absorption characteristic) as possible. Here, the coating layer 11 will be described.

[0021] The coating layer 11 is a layer for adjusting the light transmission characteristics of the substrate 10. The coating layer 11 is formed by applying a coating agent to the substrate 10 and drying it. The coating agent is composed of an absorber, an additive, and a solvent. The absorber functions to absorb light in a certain wavelength range. The absorber is adjusted by mixing multiple types of visible light blocking agents (e.g., VIS absorbers) that absorb light of specific wavelengths to obtain the desired filter characteristics. The filter characteristics referred to here are, for example, a transmittance of less than 65% in the 400-480 nm range, and the convolution integral of this filter characteristic with the absorption spectrum of (standard) human blue cone cells in the 400-480 nm wavelength range is such that the convolution integral of this filter characteristic with the absorption spectrum in that wavelength range is cut by 40% or more compared to the convolution integral of the reference filter characteristic with 100% transmittance and the reference absorption spectrum in that wavelength range. On the other hand, if the cutoff rate is too high, it will hinder the visibility of healthy people sharing the same room. From this perspective, a cutoff rate of, for example, 80% or less is preferable.

[0022] Furthermore, the filter characteristics preferably exhibit a transmittance of 55% or more in the green wavelength band above 500 nm (e.g., wavelength band of 520 to 630 nm) and / or red wavelength band (e.g., wavelength band of 550 to 650 nm), and more preferably exhibit a transmittance of 60% or more, more preferably exhibit a transmittance of 70% or more, more preferably exhibit a transmittance of 80% or more, and further include a transmittance of 90% or more. The filter characteristics relating to the green or red wavelength band above 500 nm will be described later.

[0023] The additives function to improve the properties of the coating layer. Examples of additives include coupling agents. The coupling agents contribute to, for example, improving adhesion between the coating layer 11 and the substrate 10, improving water resistance, and improving uniformity. The solvent is selected taking into consideration various properties to obtain the desired coating layer. For example, at least one of butanol, methyl isobutyl ketone, butyl acetate, methyl ethyl ketone, dipropylene glycol methyl ether (DPGM), and propylene glycol monomethyl ether acetate (PGM-AC) is used. The composition of the coating agent is designed depending on the desired properties of the coating layer 11. In one example, the coating agent has a composition of 0.4 to 12 wt % absorbent, 40 to 90% solvent, and 0 to 60 wt % additive.

[0024] In one example, the coating agent itself does not contain Ag (Ag fine particles) or an adhesive. The adhesive may be, for example, an acrylic adhesive, a polyester adhesive, a polyurethane adhesive, a rubber adhesive, or a silicone adhesive.

[0025] The coating agent can be applied by spray coating, dip coating, spin coating, brush coating, roller coating, or hand coating.

[0026] The substrate 10, i.e., the light-transmitting material 1, to which the coating layer 11 is applied has predetermined filter characteristics. In this example, the predetermined filter characteristics refer to a filtering function for transmitting or blocking light of a specific wavelength. In this example, the predetermined filter characteristics are expressed by an index that is quantified based on a predetermined method. Here, the filter characteristics defined in the present invention will be described.

[0027] Here, the filter characteristic of the light-transmitting material 1 is such that the convolution integral of this filter characteristic and the absorption spectrum of human blue cone cells in the wavelength band of 400 to 480 nm is cut by 40% or more from the convolution integral of the reference filter characteristic and its absorption spectrum in the same wavelength band. The reference filter characteristic is a characteristic that provides 100% transmittance in this wavelength band.

[0028] 5A is a graph illustrating an example of a reference filter characteristic. In the graph h(x) of FIG. 5A, the vertical axis represents transmittance (%) and the horizontal axis represents the wavelength of light (nm). In this example, the reference filter characteristic represents a hypothetical characteristic in which the transmittance of light is constant at 100% in the target wavelength band (here, 400 to 480 nm).

[0029] 5B is a graph illustrating the light absorption spectrum of human blue cone cells. In this example, among the curves representing graph g(x), the curve for the target wavelength band (here, 400-480 nm) is shown by a solid line, and the curves for other wavelength bands are shown by dashed lines. Because the light sensitivity of patients with photosensitivity differs from that of healthy individuals, the characteristics of the light absorption spectrum of blue cone cells in healthy individuals are needed as a comparison material to evaluate the degree to which a manufactured light-transmitting material can control light transmission.

[0030] In this embodiment, a method (an example of a predetermined method) using the convolution integral of transmittance and absorbance is adopted to quantitatively evaluate the performance of the filter characteristics of a light-transmitting material. Convolution generally refers to a binomial operation (also called convolution) in which one function is superimposed on another function while being translated. In this example, the convolution integral in the wavelength band of 400 to 480 nm between a graph h(x) representing the reference filter characteristics of 100% transmittance and a graph g(x) representing the absorption spectrum of blue cone cells in a healthy subject is calculated using the following formula (1):

[0031] In the present invention, for example, when a region represented by graph h(x) in the wavelength band of 400 to 480 nm is translated with a graph g(x) in the same wavelength band of 400 to 480 nm, the sum of the areas of the overlapping regions is defined as the convolution integral. In this example, in formula (1), C100(X) represents the convolution integral of graph h(x) and graph g(x) in the wavelength band of 400 to 480 nm. A specific method for calculating the convolution integral will be described below.

[0032] 6 is a table 1000 showing an example of calculating the convolution integral for a reference filter characteristic with a transmittance of 100%. For simplicity, the absorbance of blue cones is read from the graph in FIG. 5B at predetermined wavelengths (every 10 nm from 400 nm to 480 nm), and the sum of the products of these values ​​and the reference filter characteristic is calculated for the wavelength band of interest, and the resulting sum is taken as the convolution integral C100(X).

[0033] As a result, the value of the convolution integral for the reference filter characteristic can be determined. The total value or reference total value (unit: "%)" represents the ratio of the convolution integral of the object to the convolution integral value of the reference filter characteristic, "65900," as the reference value (corresponding to the so-called "cut rate"). The filter characteristic of the coating layer 11 produced in this embodiment is evaluated in terms of performance by comparing it with this reference value. The cut rate will be described later. Next, the predetermined filter characteristic of the coating layer 11 will be described.

[0034] Because brightness sensitivity varies greatly among individuals, when aiming for a lighting environment in which multiple users, including those with photosensitivity, can coexist, it is necessary to maintain a certain level of brightness while suppressing the transmittance in the wavelength range of 400 to 480 nm for the benefit of those with photosensitivity. Therefore, when setting an upper limit for brightness (i.e., light transmittance) in this example, for example, it is preferable that the transmittance in the range of 400 to 480 nm be less than 65%, and more preferably in the range of 30 to 60%.

[0035] Furthermore, it is preferable that the convolution integral C(X) of the light-transmitting material 1 be cut by 40% or more (lower by 40% or more) based on the convolution integral C100(X). The convolution integral C(X) is the convolution integral of a predetermined filter characteristic and the absorption spectrum of human blue cone cells in the target wavelength band (here, 400 to 480 nm), and is expressed by the following equation (2):

[0036] The cut rate fc is expressed by the following equation (3).

[0037] According to research by the inventors of the present application, by setting the cut rate fc to 40% or more, it is possible to suppress the occurrence of visual perception disorders due to photosensitivity.

[0038] The inventors of the present application prepared a stock solution for producing the coating layer 11 as follows, diluted it, and applied it to a test substrate 10 (a glass plate to be tested) to prepare a sample. The composition of the stock solution for the coating layer 11 in this example is as shown in Table 1 below.

[0039] The above-mentioned stock solution was used directly or diluted with a solvent to obtain a coating agent. Using this coating agent, a sample was prepared using the following procedure. The operator aspirated the coating agent obtained using the stock solution with a dropper and dispensed a predetermined amount onto a glass plate for the sample, measuring 40 mm (length) x 40 mm (width) x 3 mm (thickness). Next, the operator used a urethane sponge to spread the coating agent uniformly (e.g., to a film thickness of 3 to 4 μm). The operator then allowed the sample to dry at room temperature for 24 hours.

[0040] The inventors of the present application prepared samples with different amounts of coating agent dropped or different dilution ratios (Table 2). DPGM was used as the solvent to dilute the coating agent. Experimental Example 1 was performed using two drops without dilution, while Experimental Examples 2 to 5 were performed using one drop, with dilution ratios of no dilution, 2x, 3x, and 4x, respectively.

[0041] Figure 7 is a photograph of the prepared sample. The sample is slightly yellowish overall. The inventors of the present application measured the transmittance spectrum (or filter characteristics) of the sample of Light Transmitting Material 1 prepared in this manner. The measurement conditions are as shown in Table 3 below.

[0042] 8 is a graph showing the light transmission spectrum measured for each sample, where the vertical axis represents transmittance (%) and the horizontal axis represents the wavelength of light (nm).

[0043] In these experimental examples, the transmission spectrum has a peak near the 410 nm wavelength band, but transmittance is generally kept low in the 400-480 nm wavelength band. On the other hand, the transmittance increases sharply when the wavelength exceeds 480 nm. That is, this transmission spectrum preferably exhibits a transmittance of 55% or more in the green wavelength band (e.g., 520-630 nm) and / or red wavelength band (e.g., 550-650 nm) above 500 nm, preferably a transmittance of 60% or more, more preferably a transmittance of 70% or more, more preferably a transmittance of 80% or more, and even includes a transmittance of 90% or more. This spectral shape can reduce the amount of light absorbed by blue cone cells while maintaining the light absorbed by other cone cells.

[0044] FIG. 9 is a table 2000 showing the calculation results of the convolution integral of the filter characteristics of the light-transmitting material according to the examples. The convolution integral of each example was calculated using the same method as in FIG. 6. In FIG. 9, the total value or reference total value is expressed as the cut rate fc of the convolution integral when the reference filter characteristic "65900" in FIG. 6 is used as the reference value. In this example, the cut rate is an index that indicates how much light has been cut (i.e., reduced) from the value of the convolution integral of the reference filter characteristic; the larger the cut rate, the smaller the overall transmittance of the light-transmitting material 1.

[0045] Here, from the viewpoint of suppressing the occurrence of visual perception disorders due to photosensitivity, a larger cutoff rate is preferable, for example, 40% or more. On the other hand, if the cutoff rate is too high, it will hinder the visibility of healthy people who spend time in the same room. From this viewpoint, a cutoff rate of, for example, 80% or less is preferable. For example, Experimental Examples 2 and 3 are preferable because they meet these conditions.

[0046] 2-2. Light-Transmitting Material with Heat-Shielding Function Next, in this embodiment, a light-transmitting material using a coating agent blended with a heat-shielding agent will be described. In this example, the heat-shielding agent is a composition blended into the coating agent for the purpose of efficiently reflecting or absorbing light with wavelengths in the infrared region contained in incident light such as sunlight, and suppressing the transmission of thermal energy. Heat-shielding agents are also called near-infrared absorbing materials, and are materials that combine high visible light transmittance with selective absorption of near-infrared light. Representative heat-shielding agents include various materials, including oxides such as ATO (Antimony-doped Tin Oxide), CWO (registered trademark) (Cesium-doped Tungsten Oxide), and ITO (Indium Tin Oxide).

[0047] ATO is highly transparent to visible light and can be used to form a transparent heat-shielding film that blocks near-infrared rays that easily turn into heat, making it suitable for use as a heat-reflecting film in low-emissivity (Low-E) glass and other applications, and it also exhibits excellent thermal insulation. Furthermore, because ATO does not block electromagnetic waves and exhibits good electrical conductivity, it is also used as a transparent electrode for liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays.

[0048] CWO can efficiently block light in the near-infrared region (for example, heat rays contained in sunlight) while maintaining high transparency in the visible light region. Furthermore, CWO is useful in that it can selectively absorb a larger amount of near-infrared light contained in sunlight, even compared to ATO and ITO. Therefore, its main applications include heat-shielding films and coating materials for automobile or building windowpanes, where it can cut heat (mainly near-infrared rays) caused by sunlight and suppress an increase in room temperature.

[0049] In addition to ATO and CWO, other materials with heat-shielding properties are also available. For example, ITO, like ATO, is a material made by doping indium into tin oxide (SnO2). It has relatively high transparency while being capable of producing a unique film with low transmittance in the near-infrared region, providing excellent near-infrared blocking capabilities. Other near-infrared absorbing materials with heat-shielding properties (particularly near-infrared cut rates) include, for example, LaB6 (lanthanum hexaboride), tungsten bronze-based metal materials, VO2 (vanadium dioxide), and other metal nanoparticles (e.g., Ag, Au). These materials are selected according to various purposes (e.g., transparency, cost, required heat-shielding performance, etc.) and are used in the form of films, coatings, kneaded materials, etc.

[0050] The heat-shielding agent in this embodiment is preferably selected so as to exhibit a high heat-shielding effect for wavelengths in the near-infrared region (e.g., 780 nm to 2500 nm). The content of the heat-shielding agent in the coating agent is preferably optimized in consideration of the required heat-shielding performance, the transparency of the coating layer, other physical properties, and the like. For example, the content is adjusted to a range of approximately 0.1 to 40 wt % with respect to the solid content of the coating agent.

[0051] The inventors of the present application prepared samples of light-transmitting materials by applying coating agents to glass, each of which was prepared by adding the following heat-shielding agents (infrared absorbing agents) to the stock solution shown in Table 1 for producing the coating layer 11, and measured their light absorption characteristics. The heat-shielding agents were added in amounts ranging from 20 to 30% of the coating agent (Table 4). (a) Heat-shielding agent A (ATO): DNT Thermoprotect PA-D, manufactured by Dai Nippon Toryo Co., Ltd., solids concentration: 40% (b) Heat-shielding agent B (CWO): Solament (registered trademark) YMF-02A, manufactured by Sumitomo Metal Mining Co., Ltd., solids concentration: 18% Thereafter, a sample was prepared in the same manner as in the experiment 2-1, diluted, and applied to a test substrate 10 (a glass plate to be tested) to prepare a sample.

[0052] The transmittance spectrum of the light transmitting material 1 produced using the coating agent containing the heat-shielding agent of this embodiment was measured to confirm its heat-shielding effect (to measure the so-called filter characteristics). The measurement conditions are as shown in Table 5 below.

[0053] 10 is a graph showing the transmittance spectra of Experimental Examples 21 to 23 and Experimental Examples 31 to 34, which have a heat-shielding function. This graph shows that the transmittance in the visible light region (400 nm to 780 nm) is almost the same as when no heat-shielding agent is added, while the transmittance in the near-infrared region (780 nm to 2000 nm) decreases significantly depending on the amount of heat-shielding agent added.

[0054] From the above, it was confirmed that the light-transmitting material 1 containing the heat-shielding agent efficiently blocks light in the near-infrared region while maintaining visible light transmittance, as shown in Figure 10. From these results, it is expected that the incorporation of the heat-shielding agent will reduce the thermal energy that penetrates indoors and contribute to improving cooling efficiency.

[0055] Furthermore, in this embodiment, in order to evaluate the effectiveness as a countermeasure against photosensitivity, the convolution integral between the filter characteristics of the light-transmitting material containing the heat-shielding agent and the absorption spectrum of human blue cone cells was calculated.

[0056] 11 is a table showing the calculation results of the convolution integral for Experimental Examples 21 to 23 and Experimental Examples 31 to 34, which have a heat-shielding function. This table shows that even if the blending amount of the heat-shielding agent is increased, the cut rate of the convolution integral with blue cone cells in the wavelength range of 400 nm to 480 nm does not change significantly compared to when the heat-shielding agent is not included. This is because the heat-shielding agent has the property of blocking light mainly in the infrared region.

[0057] As a result, as shown in Figure 11, in this embodiment, even when a heat-shielding agent is blended, the effect of suppressing blue light transmission is maintained, and it has been shown that heat-shielding performance can be imparted without impairing the effect of suppressing visual perception disorders in patients with photosensitivity. In this way, according to this embodiment, it is possible to provide a light-transmitting material that achieves both a countermeasure against photosensitivity and a heat-shielding countermeasure.

[0058] Up to this point, in this embodiment, we have mainly described filter characteristics that adjust the absorption of light in blue (S) cone cells. However, when a heat-shielding agent is added, its effect on the light transmittance of green (M) cone cells and / or red (L) cone cells is also taken into consideration. Although the primary function of a heat-shielding agent is to block near-infrared light, its composition may change the transmittance characteristics of the visible light range, particularly green or red light. Significant fluctuations in the transmittance in these wavelength ranges may cause discrepancies in color perception or impair the overall brightness perception of the room. Therefore, in this example, we aim to provide a more natural and comfortable visual environment while maintaining color reproducibility and ensuring sufficient brightness by evaluating the cut rate based on the convolution integral with the absorption spectra of green and red cone cells in addition to the heat-shielding effect.

[0059] Fig. 12 is a table illustrating the cutoff rates of a light-transmitting material with heat-shielding properties, calculated by convolution with the absorption spectrum of green cone cells. This table shows the cutoff rates (%) for green (M) cone cells in Experimental Examples 21-23 and Experimental Examples 31-34, and was calculated using the same method and formula as used to evaluate the cutoff rate for blue cone cells in Fig. 9 . Specifically, the absorbance of green (M) cone cells was read from the graph in Fig. 3A at predetermined wavelengths (e.g., every 10 nm from 520 nm to 630 nm), and the sum of the products of these values ​​and the reference filter characteristics (e.g., a graph showing 100% transmittance) was calculated for the target wavelength range. Furthermore, the cutoff rates (%) for Experimental Examples 21-23 and Experimental Examples 31-34 were calculated using the reference value of "71400," which is the sum of the convolution integrals for the reference filter characteristics.

[0060] FIG. 13 is a table illustrating the cutoff rates (%) of light-transmitting materials with heat-shielding properties calculated by convolution with the absorption spectrum of red cone cells. This table shows the cutoff rates (%) for red (L) cone cells in Experimental Examples 21-23 and Experimental Examples 31-34, calculated using the same method and formula as used for the evaluation of the cutoff rate for blue (S) cone cells in FIG. 9 . Again, the absorbance of red (L) cone cells was read from the graph in FIG. 3A at predetermined wavelengths (e.g., every 10 nm from 550 nm to 650 nm), and the sum of the products of these values ​​and the reference filter characteristics (e.g., a graph showing 100% transmittance) was calculated for the target wavelength band to obtain the total value of the convolution. Furthermore, the cutoff rates (%) for Experimental Examples 21-23 and Experimental Examples 31-34 were calculated using the reference value of "74400," the total value of the convolution integral for the reference filter characteristics.

[0061] As shown in Figures 12 and 13, in each experimental example in which a heat-shielding agent was added, the cutoff rate was calculated by convolution integral with green cone cells and red cone cells. It is believed that in order for humans to perceive natural color tones, it is necessary to maintain the transmittance of green light and red light at a certain level or higher. In this embodiment, a cutoff rate of 40% or less, 35% or less, or 30% or less for green (M) cone cells is preferred as a threshold for minimizing visual discomfort. Furthermore, a cutoff rate of 45% or less, 40% or less, or 35% or less for red (L) cone cells is preferred as a threshold.

[0062] While the blue light blocking rate is set high as a countermeasure against photosensitivity, if the green or red light blocking rate is too high, it may cause distortion of color vision and a decrease in overall brightness. Therefore, it is desirable to keep these blocking rates as low as possible. As such, when adjusting the type or amount of heat-shielding agent, it is important to comprehensively evaluate not only the blue light blocking rate but also the effects on the transmittance of green and red light to achieve balanced filter characteristics. As described above, according to this embodiment, it is possible to provide a light-transmitting material that further enhances the visual satisfaction of a variety of users, including healthy individuals, while taking into consideration patients with photosensitivity.

[0063] 3. Modifications The present invention is not limited to the above-described embodiment, and various modifications are possible. Some modifications will be described below. Two or more of the following features may be combined and applied.

[0064] (1) Light-Transmitting Material 1 The concentrate (or material), shape, or function of the light-transmitting material 1 is not limited to those exemplified in the embodiments. The light-transmitting material 1 may have any concentrate (or material), shape, or function as long as it can achieve the required function. For example, the light-transmitting material 1 may be any material, and instead of the substrate 10 in the present embodiment in which the coating layer 11 is applied to a window, the light-transmitting material 1 may be installed to block specific wavelengths of a fluorescent lamp or an LED bulb. In this case, the coating layer 11 may be applied to the outer wall of the fluorescent lamp or the LED bulb. Furthermore, the light-transmitting material 1 may be used not only for building windows, but also for automobile windshields, fluorescent lamps or lighting fixtures in buildings, eyeglasses (or contact lenses), and the like. For example, the light-transmitting material 1 may be applied to the windshield of a car. In this example, assuming that a healthy person, rather than a photosensitive patient, is driving a car, when the amount of light entering from the outside temporarily increases, for example, when exiting a tunnel, the light-transmitting material 1 applied to the windshield can limit the amount of light transmitted and protect the driver's field of vision. In this way, the light transmitting material 1 can provide an effective bright environment even for healthy people.

[0065] (2) Coating Layer 11 The coating layer 11 is not limited to those exemplified in the embodiment. The coating layer 11 may have any stock solution, composition, content, or function as long as it can achieve the required function. Here, the coating layer 11 may be, for example, a secondary product such as a film, sheet, sticker, or membrane, instead of a product (e.g., a primary product) that is applied to a window as the substrate 10 in this embodiment. Furthermore, the coating layer 11 may have various changes in the composition ratio or content ratio of the various stock solutions in this embodiment. In fact, the stock solutions themselves may be changed.

[0066] (3) Filter Characteristics The filter characteristics are not limited to those exemplified in the embodiment. In this example, the filter characteristics may be defined in any way, and may be light absorbance instead of light transmittance. Furthermore, the reference filter characteristics may be defined in any way. For example, the light absorption spectrum of human blue cone cells used as the reference filter characteristics may be that of people of any age, sex, race, group (or individual), or brightness sensitivity. The settings of the predetermined filter characteristics may be changed in response to changes in the reference filter characteristics.

[0067] (4) Cut Rate The cut rate is not limited to the one exemplified in the embodiment. In this example, the cut rate of the convolution integral may be any numerical value or numerical range. In this example, the cut rate may be changed depending on the location or situation in which the light-transmitting material 1 is used. For example, if the light-transmitting material 1 is used in a classroom window, the cut rate may be changed depending on the sunlight exposure of the classroom (e.g., facing south or east).

[0068] (5) Infrared Cut The light-transmitting material may have the property of cutting infrared rays. Here, infrared rays refer to light with wavelengths ranging from 700 nm to 1 mm. Cutting infrared rays means that the integrated cut rate in the infrared region is greater than a threshold value. The infrared region refers to at least one wavelength band of near-infrared (NIR, 700 nm to 2.5 μm), mid-infrared (MIR, 2.5 μm to 25 μm), and far-infrared (FIR, 25 μm to 1 mm). Alternatively, the near-infrared region may be defined as a range of 800 nm to 1400 nm. The threshold value of the integrated cut rate is, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%.

[0069] (6) UV Cut The light-transmitting material may have the property of cutting ultraviolet rays. Here, ultraviolet rays refer to light with a wavelength shorter than 400 nm. Cutting ultraviolet rays means that the integrated cut rate in the ultraviolet region is greater than a threshold value. The ultraviolet region refers to at least one wavelength band of so-called UVA (ultraviolet A rays, 315 nm to 400 nm), UVB (ultraviolet B rays, 280 nm to 315 nm), and UVC (ultraviolet C rays, 100 nm to 280 nm). The threshold value of the integrated cut rate is, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%.

[0070] (7) User The user, i.e., the user, is not limited to those exemplified in the embodiment. The light-transmitting material 1 may be used for cataract prevention. That is, the user may be a cataract patient. Some of the users may include healthy people or those with no abnormalities in eye function. In this example, the target users are humans with various brightness sensitivities, but the target users may also be animals such as pets. Or, the target users may also be plants whose growth rate changes depending on a specific wavelength of light.

[0071] 1...light transmitting material, 10...substrate, 11...coating agent, 1000, 2000, 3000, 4000, 5000...surface

Claims

1. A light-transmitting material coated with a coating agent having specified filter characteristics, which has a transmittance of less than 65% in the range of 400 to 480 nm, and the convolution integral of the specified filter characteristics and the absorption spectrum of human blue cone cells in the wavelength range of 400 to 480 nm is such that the convolution integral of the reference filter characteristic of 100% transmittance and the absorption spectrum in the wavelength range is cut by 40% or more and 80% or less.

2. The light-transmitting material according to claim 1, wherein the filter characteristics are such that the transmittance in the green and red wavelength bands above 500 nm is 55% or more.

3. The light-transmitting material according to claim 1, wherein the coating agent contains a heat-shielding agent.

4. The light-transmitting material according to claim 3, wherein the convolution integral of the predetermined filter characteristic and the absorption spectrum of human green cone cells in the wavelength band of 520 to 630 nm is cut by 30% or less from the convolution integral of the reference filter characteristic of 100% transmittance and the absorption spectrum in the wavelength band.

5. The light-transmitting material according to claim 3 or 4, wherein the convolution integral of the predetermined filter characteristic and the absorption spectrum of human red cone cells in the wavelength band of 550 to 650 nm is cut by 40% or less from the convolution integral of the reference filter characteristic of 100% transmittance and the absorption spectrum in the wavelength band.

6. A window comprising the light-transmitting material of claim 1.

7. A lighting fixture comprising the light-transmitting material according to claim 1.

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