Cover glass and digital signage

Abstract

Provided is a cover glass that is capable of effectively increasing visibility. The cover glass according to the present invention includes a glass plate 2, an anti-glare layer 3 provided on the glass plate 2, and an anti-reflection film 4 provided on the anti-glare layer 3, and is characterized in that, assuming that the image clarity is DOI, the gloss is G, the haze is H, the glitter index value is S, and the reflection index value is C, the visibility parameter P in equation (1) is 150-2000. Equation (1): P = (100000×DOI) / (G×H×S×C)

Description

Technical Field

[0001] The present invention relates to a cover glass and a digital signage using the same.

Background Art

[0002] Cover glass is widely used for displays such as mobile phones, tablet terminals, televisions, and digital signage. The visibility of such displays may deteriorate due to reflected external light or the like. Therefore, various attempts have been made to improve the visibility of displays. For example, Patent Document 1 below discloses a translucent structure having an uneven structure for enhancing antiglare properties and the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, digital signage and the like are often used outdoors under sunlight. The visibility of a display under sunlight is significantly different from that indoors. In recent years, further improvement in visibility has been required for displays used outdoors, but it is difficult to sufficiently enhance the visibility with the translucent structure described in Patent Document 1.

[0005] An object of the present invention is to provide a cover glass and a digital signage that can effectively enhance visibility.

Means for Solving the Problems

[0006] The cover glass of the present invention comprises a glass plate, an anti-glare layer provided on the glass plate, and an anti-reflective film provided on the anti-glare layer, and is characterized in that, when DOI is the image clarity, G is the glossiness, H is the haze, S is the glare index value, and C is the reflection index value, the visibility parameter P in the following formula (1) is 150 or more and 2000 or less.

[0007] P=(100000×DOI) / (G×H×S×C)…Equation (1)

[0008] The cover glass described above preferably further comprises an anti-fouling layer provided on the anti-reflective coating.

[0009] The digital signage of the present invention is characterized by comprising the above-mentioned cover glass. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide cover glass and digital signage that can effectively enhance visibility. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a front cross-sectional view of a cover glass according to one embodiment of the present invention. [Figure 2] Figure 2 is a photograph of the cover glass of Comparative Example 1. [Figure 3] Figure 3 is a photograph of the cover glass of Comparative Example 2. [Figure 4] Figure 4 is a photograph of the cover glass of Example 1. [Figure 5] Figure 5 is a photograph of the cover glass of Example 2. [Figure 6] Figure 6 is a photograph of the cover glass of Example 3. [Figure 7] Figure 7 is a photograph of the cover glass of Example 4. [Figure 8] Figure 8 shows photographs of the cover glass of Example 1 and Comparative Example 2 under sunlight. [Modes for carrying out the invention]

[0012] Preferred embodiments are described below. However, the following embodiments are merely illustrative, and the present invention is not limited to these embodiments. In addition, in each drawing, components having substantially the same function may be referred to by the same reference numerals.

[0013] (Cover glass) Figure 1 is a front cross-sectional view of a cover glass according to one embodiment of the present invention. The cover glass 1 shown in Figure 1 can be used in a display. The cover glass 1 comprises a glass plate 2, an anti-glare layer 3 provided on the glass plate 2, an anti-reflective film 4 provided on the anti-glare layer 3, and, if necessary, an anti-fouling layer 5 provided on the anti-reflective film 4. By providing the anti-reflective film 4 on the anti-glare layer 3, the bright-field contrast of the cover glass 1 can be improved.

[0014] The glass plate 2 can be made of, for example, alkali-free glass, soda-lime glass, borosilicate glass, aluminosilicate glass, or chemically strengthened glass.

[0015] The anti-glare layer 3 has an uneven surface structure. The anti-glare layer 3 is provided to suppress reflections of external light, thus providing a so-called anti-glare effect.

[0016] The anti-glare layer 3 preferably has an uneven structure composed of inorganic materials. The inorganic materials constituting such an anti-glare layer 3 preferably include oxides such as silica, alumina, zirconia, and titania, and can be formed from an inorganic paint. As the main component of the inorganic paint, silica precursors, alumina precursors, zirconia precursors, titania precursors, etc., can be used. Among these, silica precursors are particularly preferred. The inorganic paint may also contain inorganic particles.

[0017] Examples of the silica precursor include alkoxysilanes such as tetraethoxysilane and tetramethoxysilane, hydrolysis condensates of alkoxysilanes (sol-gel silica), silazane, etc. From the viewpoint of further enhancing the antiglare effect, at least one of alkoxysilanes such as tetraethoxysilane and tetramethoxysilane, and hydrolysis condensates thereof is preferable, and a hydrolysis condensate of tetraethoxysilane is more preferable.

[0018] Examples of the alumina precursor include aluminum alkoxide, hydrolysis condensate of aluminum alkoxide, water-soluble aluminum salt, aluminum chelate, etc.

[0019] Examples of the zirconia precursor include zirconium alkoxide, hydrolysis condensate of zirconium alkoxide, etc.

[0020] Examples of the titania precursor include titanium alkoxide, hydrolysis condensate of titanium alkoxide, etc.

[0021] Examples of the inorganic particles include silica particles, alumina particles, zirconia particles, titania particles, etc. Among these, silica particles are particularly preferably used.

[0022] The antiglare layer 3 can be formed by applying the above inorganic paint onto the glass plate 2. For example, the above inorganic paint can be applied onto the glass plate 2 by a spray coating method. After application, it is dried and fired to form the antiglare layer 3 made of an inorganic substance.

[0023] The average thickness of the antiglare layer 3 is preferably 0.1 μm or more and 2 μm or less, more preferably 0.15 μm or more and 1.75 μm or less, and still more preferably 0.2 μm or more and 1 μm or less.

[0024] The anti-reflective film 4 can be formed, for example, from a dielectric multilayer film. Examples of such dielectric multilayer films include a laminated film having a low refractive index layer made of a silicon oxide layer and a high refractive index layer made of an oxide of at least one metal selected from the group consisting of niobium, titanium, zirconium, yttrium, tungsten, aluminum, and hafnium. It is preferable that the high refractive index layer has a niobium oxide layer. It is preferable that the low refractive index layer and the high refractive index layer are stacked alternately.

[0025] The thickness of each layer constituting the anti-reflective film 4 is preferably 1 nm or more and 300 nm or less, more preferably 2 nm or more and 200 nm or less, and even more preferably 3 nm or more and 150 nm or less. Furthermore, the total number of layers constituting the anti-reflective film 4 is preferably 2 to 6 layers. By keeping the thickness within this range, an effective and easily formed film can be created.

[0026] The anti-reflective film 4 can be formed, for example, by sputtering, CVD, or vacuum deposition. The overall thickness of the anti-reflective film 4 is preferably 50 nm or more and 1000 nm or less, more preferably 75 nm or more and 750 nm or less, and even more preferably 100 nm or more and 500 nm or less.

[0027] The antifouling layer 5 preferably contains an organosilicon compound. The inclusion of an organosilicon compound improves adhesion with the anti-reflective film 4. This makes the antifouling layer 5 less likely to peel off even after prolonged use.

[0028] Examples of organosilicon compounds include one or more compounds selected from silane coupling agents, silicone oils, silicone resins, silicone rubbers, hydrophobic silica, and fluorine-containing organosilicon compounds.

[0029] The thickness of the anti-fouling layer 5 is preferably 0.5 nm or more and 20 nm or less, more preferably 0.75 nm or more and 15 nm or less, and even more preferably 1 nm or more and 10 nm or less.

[0030] The method for forming the antifouling layer 5 is not particularly limited, and for example, it can be formed by applying a diluted solution of an organosilicon compound or the like using a spray coating method.

[0031] Indicators of visibility include image clarity (DOI), gloss (G), haze (H), sparkle (S), and clarity (C).

[0032] Image sharpness DOI is an index of visual resolution or clarity. A smaller image sharpness DOI indicates a less clear image, while a larger image sharpness DOI indicates a clearer image. A preferred image sharpness DOI is 20% or higher, more preferably 25% or higher, and even more preferably 30% or higher. While there is no particular upper limit to the image sharpness DOI, it can be, for example, 90%.

[0033] Glossiness G is an index indicating the degree of light reflection. The lower the glossiness G, the lower the degree of reflection and the better the visibility. Glossiness G is preferably 100 or less, more preferably 80 or less, and even more preferably 60 or less. The lower limit of glossiness G is not particularly limited, but for example, it can be 15.

[0034] Haze H is an indicator of light transmittance, showing the degree of cloudiness of a translucent material. A lower haze H indicates less cloudiness and better visibility. Haze H is preferably 60% or less, more preferably 50% or less, and even more preferably 40% or less. The lower limit of haze H is not particularly limited, but for example, it can be 10%.

[0035] The glare index value S indicates the degree to which RGB pixels or brightness variations appear as numerous light points or other flickering effects on a display or the like. A lower glare index value S indicates less glare and better visibility. The glare index value S is preferably 6% or less, more preferably 5% or less, and even more preferably 4% or less. The lower limit of the glare index value S is not particularly limited, but for example, it can be 1.5%.

[0036] The reflection index value C is an index that indicates the degree to which ambient light is reflected. The lower the reflection index value C, the less ambient light is reflected, resulting in better visibility. The reflection index value C is preferably 6% or less, more preferably 5% or less, and even more preferably 4% or less. The lower limit of the reflection index value C is not particularly limited, but for example, it can be 2%.

[0037] A key feature of this embodiment is that, when the visibility parameter P is denoted as P, the visibility parameter P in the following equation (1) is between 150 and 2000. This effectively enhances visibility. This will be explained below.

[0038] P=(100000×DOI) / (G×H×S×C)…Equation (1)

[0039] As described above, a higher image clarity (DOI) is preferable, while lower gloss (G), haze (H), glare index (S), and reflection index (C) are preferable. However, there is a trade-off relationship between haze (H) and reflection index (C), and sometimes there is a trade-off relationship between image clarity (DOI) and reflection index (C). Therefore, in practice, it is difficult to achieve ideal values ​​for all of these: image clarity (DOI), gloss (G), haze (H), glare index (S), and reflection index (C). Furthermore, the visibility environment outdoors under sunlight is significantly different from the indoor environment. Therefore, conventional cover glass and the like make it difficult to sufficiently improve the visibility of displays outdoors.

[0040] In contrast, in this embodiment, the visibility parameter P is defined by the above formula (1). Visibility is influenced by a combination of factors, including image sharpness DOI, glossiness G, haze H, glare index value S, and reflection index value C. By defining the visibility parameter P, a comprehensive index can be obtained. Furthermore, in this embodiment, the visibility parameter P is set to be between 150 and 2000. In other words, the inventors have found that visibility can be effectively enhanced by maintaining a good balance between image sharpness DOI, glossiness G, haze H, glare index value S, and reflection index value C so that they fall within this range. The cover glass 1 is particularly suitable for use in digital signage and the like, which are placed outdoors. However, the cover glass 1 is also suitable for use in displays used indoors.

[0041] The visibility parameter P is preferably 200 or higher, more preferably 300 or higher, even more preferably 400 or higher, and even more preferably 500 or higher. Furthermore, the visibility parameter P is preferably 1750 or lower, more preferably 1500 or lower, even more preferably 1000 or lower, and even more preferably 800 or lower. This further enhances visibility.

[0042] Referring to Figure 1, an example of a method for manufacturing a cover glass according to the present invention will be described below.

[0043] (Method of manufacturing cover glass) First, an anti-glare layer 3 is formed on the glass plate 2. For example, an inorganic coating for the anti-glare layer 3 can be applied to the glass plate 2 by a spray coating method. Examples of nozzles used in the spray coating method include two-fluid nozzles and one-fluid nozzles. Here, mutually orthogonal directions are defined as the x-direction and the y-direction. For example, the inorganic coating may be applied while moving the nozzle in the x-direction, then the nozzle may be moved in the y-direction, and then the inorganic coating may be applied again while moving the nozzle in the x-direction, and this process may be repeated. After applying the inorganic coating, it is dried and then fired. The firing temperature can be, for example, 160°C or higher and 200°C or lower.

[0044] Next, the resulting coated glass plate is washed with water. Then, the coated glass plate is dried, and subsequently, the coated glass plate is cleaned by plasma treatment. Note that the above cleaning is not necessarily required.

[0045] Next, an inorganic coating for the anti-glare layer 3 is applied again to the coated glass plate. Then, it is dried and then fired. Through this process, the anti-glare layer 3 can be formed. By applying the inorganic coating twice in this manner, or by selecting the main component of the inorganic coating and adding inorganic particles as needed, and by adjusting the application conditions such as the type of nozzle, atomizing air pressure, flow rate of the inorganic coating liquid, nozzle movement speed, nozzle movement pitch, temperature and humidity during application, surface temperature of the glass plate, and particle size of the coating liquid droplets sprayed from the nozzle, the visibility parameter P can be effectively adjusted, and the visibility parameter P can be more reliably adjusted within the range of 150 to 2000.

[0046] Alternatively, a second coat of inorganic paint may be applied after the first coat without firing and cleaning. In this case as well, the visibility parameter P can be effectively adjusted. Note that the inorganic paint does not necessarily have to be applied twice; the anti-glare layer 3 may be formed with a single application.

[0047] Next, an anti-reflective film 4 is formed on the anti-glare layer 3. In forming the anti-reflective film 4, for example, a low refractive index layer with a relatively low refractive index and a high refractive index layer with a relatively high refractive index are alternately laminated using a method such as sputtering, CVD, or vacuum deposition. This allows the anti-reflective film 4 to be formed.

[0048] Next, an antifouling layer 5 is formed on the anti-reflective film 4. The antifouling layer 5 can be formed, for example, by applying a diluted solution of an organosilicon compound or the like using a spray coating method.

[0049] When forming each of the above layers in the cover glass 1, the visibility parameter P may be adjusted by adjusting the combination of materials and film thickness of the anti-glare layer 3, the anti-reflective film 4, and the anti-fouling layer 5.

[0050] (Digital signage) The digital signage of the present invention comprises the cover glass 1 and a display element. The cover glass 1 may be any cover glass according to the present invention. The display element has a display surface. The display surface is the surface on which an image is displayed. The cover glass 1 is provided on the display surface. Because the digital signage is equipped with the cover glass 1 of the present invention, visibility can be effectively enhanced.

[0051] The effects of the cover glass according to the present invention will be explained in more detail below with reference to examples.

[0052] <Examples> (Example 1) First, a 100mm square glass plate with a thickness of 0.5mm, made of alkali-free glass, was prepared. Next, an inorganic paint containing an alkoxide such as tetraethoxysilane was applied to the glass plate using a spray coating method. Here, the direction in which one edge of the main surface of the glass plate extends was defined as the x-direction, and the direction perpendicular to the x-direction was defined as the y-direction. After applying the inorganic paint while moving the nozzle in the x-direction, the nozzle was moved in the y-direction, and then the inorganic paint was applied again while moving the nozzle in the x-direction, and this process was repeated. The nozzle's movement speed in the x-direction was set to 45m / min, the inorganic paint flow rate to 4.8g / min, and the nozzle's movement pitch in the y-direction to 2mm. The humidity during application was 54.7%, and the temperature was 19.6℃.

[0053] Next, the inorganic coating on the glass plate was fired at 180°C. Then, the resulting coated glass plate was washed with water. Next, the coated glass plate was dried, and then the coated glass plate was cleaned by plasma treatment.

[0054] Next, the same inorganic paint as described above was applied again to the coated glass plate using the spray coating method. The nozzle's x-direction travel speed was 45 m / min, the inorganic paint flow rate was 4.8 g / min, and the nozzle's y-direction travel pitch was 2 mm. The humidity during application was 55.3%, and the temperature was 19.6°C. Next, the inorganic paint on the coated glass plate was fired at 180°C. As a result, an anti-glare layer was formed on the glass plate. The average thickness of the anti-glare layer was 0.35 μm.

[0055] Next, a low refractive index layer made of silicon oxide was formed on the anti-glare layer by sputtering. Then, a high refractive index layer made of niobium oxide was formed on the low refractive index layer by sputtering. By repeating these steps, an anti-reflective film consisting of a laminate of low refractive index and high refractive index layers was formed on the anti-glare layer. The low refractive index layer consisted of two layers, with thicknesses of 35 nm and 78 nm from the glass plate side. The high refractive index layer also consisted of two layers, with thicknesses of 10 nm and 106 nm from the glass plate side. The overall thickness of the anti-reflective film was 229 nm.

[0056] Next, a diluted fluorine-based antifouling solution was applied to the anti-reflective coating using a spray coating method, and then dried to form an antifouling layer. The thickness of the antifouling layer was 4 nm.

[0057] (Example 2) In forming the anti-glare layer, a cover glass was prepared in the same manner as in Example 1, except that a second application of inorganic paint was performed without firing and cleaning after the first application of inorganic paint. Specifically, in forming the anti-glare layer, the same inorganic paint as in Example 1 was applied to the glass plate by spray coating. The nozzle's x-direction movement speed was 45 m / min, the inorganic paint flow rate was 4.8 g / min, and the nozzle's y-direction movement pitch was 2 mm. Next, the same inorganic paint as above was applied again to the inorganic paint applied to the glass plate by spray coating. The nozzle's x-direction movement speed was 45 m / min, the inorganic paint flow rate was 4.8 g / min, and the nozzle's y-direction movement pitch was 2 mm. The humidity during application was 54.7%, and the temperature was 19.6°C.

[0058] Next, the inorganic coating on the glass plate was fired at 180°C. This formed an anti-glare layer on the glass plate. The average thickness of the anti-glare layer was 0.33 μm.

[0059] (Example 3) Except for the difference in humidity and temperature during the first and second applications of the inorganic paint during the formation of the anti-glare layer, the cover glass was prepared in the same manner as in Example 1. Specifically, the humidity during the first application of the inorganic paint was 50.9% and the temperature was 19.9°C. During the second application of the inorganic paint, the humidity was 51.2% and the temperature was 19.9°C. The average thickness of the anti-glare layer was 0.47 μm.

[0060] (Example 4) Except for the difference in humidity and temperature during the application of the inorganic paint when forming the anti-glare layer, the cover glass was prepared in the same manner as in Example 2. Specifically, the humidity during the application of the inorganic paint was 50.9%, and the temperature was 19.9°C. The average thickness of the anti-glare layer was 0.49 μm.

[0061] (Example 5) Except for the difference in humidity and temperature during the application of the inorganic paint when forming the anti-glare layer, the cover glass was prepared in the same manner as in Example 2. Specifically, the humidity during the application of the inorganic paint was 52.8%, and the temperature was 21.4°C.

[0062] (Example 6) Except for the fact that the inorganic paint was applied only once to form the anti-glare layer, and the conditions for applying the inorganic paint by spray coating, as well as the humidity and temperature during application, were different from those in Example 2, the cover glass was prepared in the same manner as in Example 2. Specifically, the nozzle's x-direction movement speed was 55 m / min, the inorganic paint flow rate was 4.8 g / min, and the nozzle's y-direction movement pitch was 1 mm. The humidity during application of the inorganic paint was 52.8%, and the temperature was 21.4°C.

[0063] (Example 7) Except for the differences in the application conditions of the inorganic paint by spray coating, as well as the humidity and temperature during application, the cover glass was prepared in the same manner as in Example 1 for the formation of the anti-glare layer. Specifically, during the first and second applications of the inorganic paint, the nozzle's x-direction movement speed was 55 m / min, the inorganic paint flow rate was 4.8 g / min, and the nozzle's y-direction movement pitch was 1 mm. The humidity during the first and second applications of the inorganic paint was 49.4%, and the temperature was 22.4°C.

[0064] (Example 8) In forming the anti-glare layer, the inorganic paint was applied only once, and the temperature of the glass plate during the application of the inorganic paint was different from that of Example 2. Except for the differences in the conditions for applying the inorganic paint by spray coating, as well as the humidity and temperature during application, the cover glass was prepared in the same manner as in Example 2. Specifically, in forming the anti-glare layer, the glass plate was heated to a surface temperature of 49.0°C, and the same inorganic paint as in Example 2 was applied to the glass plate. The nozzle's x-direction movement speed was 45 m / min, the inorganic paint flow rate was 4.8 g / min, and the nozzle's y-direction movement pitch was 1 mm. The humidity during application of the inorganic paint was 52.2%, and the temperature was 20.0°C.

[0065] (Example 9) A protective film was applied to the side of the glass plate that did not have an anti-glare layer. Next, the glass plate was etched. Specifically, the glass plate was immersed in a 3% by weight hydrogen fluoride solution for 3 minutes. This etching process removed dirt adhering to the surface of the glass plate. Next, the surface of the glass plate was frosted. Specifically, the glass plate was immersed in a mixed solution of 15% by weight hydrogen fluoride and 15% by weight potassium fluoride. The immersion temperature was 23°C and the immersion time was 60 seconds. This formed an anti-glare layer.

[0066] Next, the glass plate was etched by immersing it in a 10% hydrogen fluoride solution for 6 minutes. After that, an anti-reflective film and an anti-fouling layer were formed in the same manner as in Example 1 to obtain a cover glass.

[0067] (Example 10) A protective film was applied to the side of the glass plate that did not have an anti-glare layer. Next, the side without the protective film was sandblasted. Then, the glass plate was etched. Specifically, the glass plate was immersed in a 3% by weight hydrogen fluoride solution for 3 minutes. This etching process removed dirt adhering to the surface of the glass plate. Next, the surface of the glass plate was frosted. Specifically, the glass plate was immersed in a mixed solution of 15% by weight hydrogen fluoride and 15% by weight potassium fluoride. The immersion temperature was 23°C and the immersion time was 360 seconds. This formed an anti-glare layer.

[0068] Next, the glass plate was etched by immersing it in a 10% hydrogen fluoride solution for 6 minutes. After that, an anti-reflective film and an anti-fouling layer were formed in the same manner as in Example 1 to obtain a cover glass.

[0069] (Comparative Example 1) Except for applying the inorganic paint in only one coat to form the anti-glare layer, and differentiating the conditions for applying the inorganic paint by spray coating from those in Example 1, the cover glass was prepared in the same manner as in Example 1. Specifically, the nozzle's x-direction movement speed was 45 m / min, the inorganic paint flow rate was 2.0 g / min, and the nozzle's y-direction movement pitch was 5 mm.

[0070] Next, the inorganic coating on the glass plate was fired at 180°C in the same manner as in Example 1. This formed an anti-glare layer on the glass plate. The average thickness of the anti-glare layer was 0.05 μm.

[0071] (Comparative Example 2) Except for the differences in the temperature of the glass plate during application of the inorganic paint, the conditions for applying the inorganic paint by spray coating, and the humidity and temperature during application, the cover glass was prepared in the same manner as in Example 2. Specifically, during the formation of the anti-glare layer, the glass plate was heated to a surface temperature of 48.2°C, and the same inorganic paint as in Example 2 was applied to the glass plate. The nozzle's x-direction movement speed was 60 m / min, the inorganic paint flow rate was 4.8 g / min, and the nozzle's y-direction movement pitch was 1 mm. The humidity during application was 52.0%, and the ambient temperature was 20.0°C. The average thickness of the anti-glare layer was 1.1 μm.

[0072] (Comparative Example 3) In forming the anti-glare layer, the inorganic paint was applied only once, and the temperature of the glass plate during the application of the inorganic paint was different from that of Example 2. Except for the differences in the conditions for applying the inorganic paint by spray coating, as well as the humidity and temperature during application, the cover glass was prepared in the same manner as in Example 2. Specifically, in forming the anti-glare layer, the glass plate was heated to a surface temperature of 48.2°C, and the same inorganic paint as in Example 2 was applied to the glass plate. The nozzle's x-direction movement speed was 45 m / min, the inorganic paint flow rate was 4.8 g / min, and the nozzle's y-direction movement pitch was 1 mm. The humidity during application of the inorganic paint was 52.0%, and the temperature was 20.0°C.

[0073] (Comparative Example 4) Except for the difference in the temperature of the glass plate and the humidity during the application of the inorganic paint when forming the anti-glare layer, the cover glass was prepared in the same manner as in Comparative Example 3. Specifically, when forming the anti-glare layer, the glass plate was heated to a surface temperature of 43.8°C. The humidity during the application of the inorganic paint was 51.8%.

[0074] (Comparative Example 5) Except for the difference in the immersion time during the frosting process compared to Example 9, the cover glass was prepared in the same manner as in Example 9. Specifically, the immersion time during the frosting process was set to 180 seconds.

[0075] (Comparative Example 6) Except for the difference in the temperature of the glass plate during application of the inorganic paint and the humidity and temperature during application of the inorganic paint, the cover glass was prepared in the same manner as in Comparative Example 3 when forming the anti-glare layer. Specifically, when forming the anti-glare layer, the glass plate was heated to a surface temperature of 48.2°C. The humidity during application of the inorganic paint was 45.5%, and the temperature was 21.1°C.

[0076] The conditions for Examples 1-8 and Comparative Examples 1-4 and 6 are summarized in Table 1 below. The conditions for Examples 9 and 10 and Comparative Example 5 are shown separately in Table 2 below.

[0077] [Table 1]

[0078] [Table 2]

[0079] (evaluation) Image clarity DOI, glossiness G, haze H, glare index S, and reflection index C were measured for the cover glass of Examples 1-10 and Comparative Examples 1-6. Image clarity DOI was measured using an SMS-1000 (Display-Messtechnik & Systeme) based on ASTM D 5767. Glossiness G was measured using a Microgloss (60°) (BYK) at an incident angle of 60° on the cover glass, based on JIS Z 8741:1997. Haze H was measured using an NDH-5000 (Nippon Denshoku) based on JIS K 7136:2000. Glare index S was measured using an SMS-1000 (Display-Messtechnik & Systeme) in sparkle measurement mode. The SMS-1000's CCD camera has a resolution of 1296 x 966 pixels, a sensor size of 1 / 3 inch, and a pixel size of 3.75 x 3.75 μm. The lens was set to a focal length of 100 mm, a lens aperture diameter of 4.5 mm, a magnification ratio of 1:1, and a permissible circle of confusion diameter of 53 μm. The pattern mask was positioned so that its top surface was located at the focal point of the lens. The reflection index value C was measured using the SMS-1000 (manufactured by Display-Messtechnik & Systeme) in reflection distribution measurement mode. A lens with a focal length of 16 mm was used, the incident angle of the incident light was set to 3°, and the distance from the illumination position on the cover glass of the example and comparative example to the lens was set to 410 mm. The cover glass of the example and comparative example was attached to a blackboard glass with an immersion solution with a refractive index of 1.53 applied to the back surface for measurement.

[0080] Furthermore, the visibility parameter P for Examples 1-10 and Comparative Examples 1-6 was calculated using formula (1) from the measured image sharpness DOI, glossiness G, haze H, glare index value S, and reflection index value C.

[0081] P=(100000×DOI) / (G×H×S×C)…Equation (1)

[0082] These results are shown in Table 3 below.

[0083] [Table 3]

[0084] As shown in Table 3, the visibility parameter P for Examples 1 to 10 is within the range of 150 to 2000. In particular, the visibility parameter P for Examples 1 to 6, 8, and 10 is within the range of 200 to 2000. On the other hand, the visibility parameter P for Comparative Example 1 is higher than 2000, and for Comparative Examples 2 to 6 it is lower than 150.

[0085] Furthermore, at an illuminance of 1000 lux, the surface of the cover glass was observed from a distance of 50 cm and an angle of 5° to evaluate reflection, glare, and resolution. These results are shown in Table 4 below. In addition, the visibility of the cover glass of Example 1 and Comparative Example 2 was compared under sunlight. Photographs of the cover glass of Examples 1-4 and Comparative Examples 1 and 2 during observation are shown in Figures 2-8.

[0086] Figure 2 is a photograph of the cover glass of Comparative Example 1. Figure 3 is a photograph of the cover glass of Comparative Example 2. Figure 4 is a photograph of the cover glass of Example 1. Figure 5 is a photograph of the cover glass of Example 2. Figure 6 is a photograph of the cover glass of Example 3. Figure 7 is a photograph of the cover glass of Example 4. Figure 8 is a photograph of the cover glass of Example 1 and Comparative Example 2 under sunlight.

[0087] [Table 4]

[0088] As shown in Table 4, Comparative Example 1 has poor visibility due to reflections, and Comparative Example 2 has poor visibility due to resolution. Furthermore, as shown in Figure 2, Comparative Example 1 shows a high degree of reflection from the lighting. As shown in Figure 3, Comparative Example 2 shows that the characters are unclear. In addition, as shown in Table 4, Comparative Examples 3, 4, and 6 have poor visibility due to resolution, and Comparative Example 5 has poor visibility due to glare.

[0089] In contrast to these, as shown in Table 4, Examples 1 to 4 exhibit good reflection, glare, and resolution. Furthermore, as shown in Figures 4 to 7, Examples 1 to 4 show little reflection, clear text, and minimal glare. Moreover, as shown in Figure 8, under sunlight, the text in Comparative Example 2 is almost invisible, indicating low visibility, while the text in Example 1 is clearly visible, demonstrating high visibility. Thus, Examples 1 to 4 exhibit high visibility. Similarly, as shown in Table 4, Examples 5 to 10 also exhibit good reflection, glare, and resolution, indicating high visibility. [Explanation of symbols]

[0090] 1…Cover glass 2…glass plate 3…Anti-glare layer 4…Anti-reflection film 5… Anti-fouling layer

Claims

1. A glass plate and The anti-glare layer provided on the glass plate, The anti-reflective film provided on the anti-glare layer, Equipped with, When the image clarity is denoted as DOI (%), and the aforementioned image clarity DOI is the image clarity measured by SMS-1000 (manufactured by Display-Mestechnik & System), and when the glossiness is denoted as G (unitless), the haze as H (%), the glare index value as S (%), and the reflection index value as C (%), the visibility parameter P in the following formula (1) is between 165 and 921. A cover glass in which the haze H is 10% or more and 60% or less. P=(100000×DOI) / (G×H×S×C)…Formula (1)

2. A glass plate and The anti-glare layer provided on the glass plate, The anti-reflective film provided on the anti-glare layer, Equipped with, When the image clarity is denoted as DOI (%), and the aforementioned image clarity DOI is the image clarity measured by SMS-1000 (manufactured by Display-Mestechnik & System), and when the glossiness is denoted as G (unitless), the haze as H (%), the glare index value as S (%), and the reflection index value as C (%), the visibility parameter P in the following formula (1) is between 165 and 921. A cover glass in which the anti-reflective coating is a laminated film having a low refractive index film and a high refractive index film, the total number of layers constituting the anti-reflective coating is 2 or more and 6 or less, and the overall thickness of the anti-reflective coating is 50 nm or more and 1000 nm or less. P=(100000×DOI) / (G×H×S×C)…Formula (1)

3. The cover glass according to claim 2, wherein the thickness of the low refractive index film and the high refractive index film of the anti-reflective coating is 1 nm or more and 300 nm or less.

4. The cover glass according to any one of claims 1 to 3, further comprising an anti-fouling layer provided on the anti-reflective film.

5. A digital signage system comprising a cover glass as described in any one of claims 1 to 4.

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