Transparent substrates with films, top plates for cookers, window glass for heating cookers, and cover glass

Abstract

To provide a transparent substrate with a film, which is excellent in light absorptive capacity and is neutral in reflection color and transparent color, and which is less likely to cause a color shift depending on an incident angle of light, and has insulation properties.SOLUTION: A transparent substrate with a film 1 includes a transparent substrate 2 and an antireflection film 3 disposed on one main surface 2a of the transparent substrate 2. The antireflection film 3 is a multilayer film including high refractive index films 5 whose refraction index is relatively high, and low refractive index films 4 whose refraction index is relatively low. At least one of the low refractive index films 4 is a light absorption film. The light absorption film includes a dielectric phase including a material whose band gap is 2.0-2.7 eV, and a metallic phase.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a film-coated transparent substrate, and a top plate for a cooker, a windowpane for a heat cooker, and a cover glass, which use the film-coated transparent substrate. [Background technology]

[0002] BACKGROUND ART Transparent substrates with a film having light-absorbing properties have been studied as top plates for cooking appliances and cover glasses for displays.

[0003] In the top plate for a cooking appliance, a film-coated glass substrate having a light-shielding film provided on the rear surface of the glass substrate is used to conceal the internal structure of the cooking appliance (for example, Patent Document 1). Also, in the cover glass for a display, a film-coated glass substrate having an anti-reflection film provided on the front surface of the glass substrate is used (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-215018 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-115105 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, a top plate for a cooking appliance may be required to clearly display various information when the light source is on, while concealing the internal structure of the cooking appliance when the light source is off. However, when a black-colored glass substrate is used as the top plate for a cooking appliance, there is a problem that various information is difficult to see when the light source is on. Furthermore, when a black inorganic pigment layer is provided as in the top plate of Patent Document 1, the color does not become achromatic black when the light source is off, and the internal structure of the cooking appliance may not be sufficiently concealed depending on the viewing angle. Therefore, there is a demand for a film-coated transparent substrate that has neutral reflected and transmitted colors and is less likely to undergo color shift depending on the angle of light incidence.

[0006] Furthermore, when a touch panel function is provided to a display such as a liquid crystal display, a cover glass provided on the front surface of the display may be required to be a transparent substrate with a highly insulating anti-reflection film.

[0007] The object of the present invention is to provide a film-coated transparent substrate that has excellent light absorption ability, neutral reflected and transmitted colors, is less likely to undergo color shift depending on the angle of incidence of light, and has insulating properties, as well as a top plate for a cooker, a window glass for a heating cooker, and a cover glass that use the film-coated transparent substrate. [Means for solving the problem]

[0008] The film-coated transparent substrate of the present invention comprises a transparent substrate and an antireflection film provided on one main surface of the transparent substrate, the antireflection film being a multilayer film including a high-refractive index film having a relatively high refractive index and a low-refractive index film having a relatively low refractive index, at least one layer of the low-refractive index film being a light-absorbing film, and the light-absorbing film including a dielectric phase containing a material having a band gap of 2.0 eV or more and 2.7 eV or less, and a metal phase.

[0009] In the present invention, the refractive index of the light-absorbing film at a wavelength of 550 nm is preferably 1.0 or more and 2.2 or less.

[0010] In the present invention, at least one layer of the high refractive index film is preferably made of at least one material selected from the group consisting of niobium oxide, silicon nitride, tantalum oxide, titanium oxide, zirconium oxide, hafnium oxide, and aluminum oxide.

[0011] In the present invention, it is preferable that the high refractive index films and the low refractive index films are alternately stacked in the multilayer film.

[0012] In the present invention, it is preferable that the outermost layer of the multilayer film on the side opposite to the transparent substrate is a film containing silicon oxide or silicon nitride.

[0013] In the present invention, the material having a band gap of 2.0 eV or more and 2.7 eV or less is preferably a metal oxide.

[0014] In the present invention, the electrical resistance of the anti-reflection film is 10 6 It is preferably Ω or more.

[0015] In the present invention, it is preferable that the luminous reflectance of the film-coated transparent substrate is 2% or less when light is incident from the antireflection film side.

[0016] In the present invention, it is preferable that the luminous reflectance of the film-coated transparent substrate is 6% or less when light is incident from the transparent substrate side.

[0017] In the present invention, the luminous transmittance of the film-coated transparent substrate is preferably 75% or less.

[0018] In the present invention, the luminous reflectance and the luminous transmittance of the film-attached transparent substrate are at least equal to or greater than L * a * b * In the color system, a when the angle of incidence of light is 0° * The absolute value of the value is 5 or less, and b *The absolute value is preferably 5 or less.

[0019] In the present invention, the luminous reflectance and the luminous transmittance of the film-attached transparent substrate are at least equal to or greater than L * a * b * In the color system, a when the angle of incidence of light is 0° * value and a when the incident angle of light is 45° * The absolute value of the difference between the values ​​is 5 or less, and the incident angle of light is 0°. * value and b when the incident angle of light is 45° * It is preferable that the absolute value of the difference between the values ​​is 5 or less.

[0020] The top plate for a cooking appliance according to the present invention comprises a film-coated transparent substrate configured according to the present invention, the transparent substrate having a cooking surface on which a cooking utensil is placed and a back surface opposite the cooking surface, and the anti-reflection film is disposed on the back surface of the transparent substrate.

[0021] The window glass for a cooking appliance according to the present invention is a window glass used in a cooking appliance, and is characterized in that it comprises a transparent substrate with a film configured according to the present invention, and the light-absorbing film is disposed on the main surface of the transparent substrate on the heating device side of the cooking appliance.

[0022] The cover glass of the present invention is a cover glass used in a display, and is characterized in that it comprises a film-coated transparent substrate configured according to the present invention, the transparent substrate being a front substrate, and the anti-reflection film being disposed on the main surface of the transparent substrate opposite to the side on which the display is provided. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a film-coated transparent substrate that has excellent light absorption ability, neutral reflected and transmitted colors, is less likely to undergo color shift depending on the angle of incidence of light, and has insulating properties, as well as a top plate for a cooking appliance, a window glass for a heating cooking appliance, and a cover glass that use the film-coated transparent substrate. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a film-coated transparent substrate according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a film-coated transparent substrate according to a second embodiment of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a film-coated transparent substrate according to a third embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a film-coated transparent substrate according to a fourth embodiment of the present invention. [Figure 5] FIG. 5 is a schematic cross-sectional view showing a top plate for a cooker according to one embodiment of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a cover glass according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] Preferred embodiments will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in each drawing, components having substantially the same functions may be referred to by the same reference numerals.

[0026] [Transparent substrate with film] (First embodiment) Fig. 1 is a schematic cross-sectional view showing a film-coated transparent substrate according to a first embodiment of the present invention. As shown in Fig. 1, the film-coated transparent substrate 1 includes a transparent substrate 2 and an antireflection film 3. The transparent substrate 2 has a first main surface 2a and a second main surface 2b that face each other. The antireflection film 3 is provided on the first main surface 2a of the transparent substrate 2.

[0027] The antireflection coating 3 is a multilayer film including a high-refractive-index film 5 having a relatively high refractive index and a low-refractive-index film 4 having a relatively low refractive index. In this embodiment, four low-refractive-index films 4 and high-refractive-index films 5 are alternately stacked on the first main surface 2a of the glass substrate 2 in order from the low-refractive-index film 4. Furthermore, a silicon oxide film 6 is provided as the outermost layer on the high-refractive-index film 5. Therefore, in this embodiment, the antireflection coating 3 is composed of a five-layer multilayer film. However, in the present invention, there is no particular limitation on the number of layers stacked in the multilayer film constituting the antireflection coating 3.

[0028] In this embodiment, each of the two low refractive index films 4 is a light absorbing film. The light absorbing film includes a dielectric phase containing a material with a band gap of 2.0 eV or more and 2.7 eV or less, and a metal phase. In the present invention, it is sufficient that at least one layer of the low refractive index films 4 is the light absorbing film.

[0029] The film-coated transparent substrate 1 of this embodiment has the above-mentioned configuration, and therefore has excellent light absorption ability, neutral reflected and transmitted colors, is less likely to undergo color shift depending on the angle of incidence of light, and is insulating.

[0030] The film-coated transparent substrate 1 of this embodiment has excellent light absorption properties and neutral reflected and transmitted colors. Therefore, when used as a top plate for a cooking appliance, for example, it can be achromatic, such as black, when the light source is off, thereby more reliably concealing the internal structure of the cooking appliance. Furthermore, the film-coated transparent substrate 1 is less susceptible to color shift depending on the angle of incidence of light, so the internal structure of the cooking appliance can be concealed regardless of the angle from which the film-coated transparent substrate 1 is viewed, and color change from the light source is less likely to occur, maintaining visibility. Furthermore, when used in a display such as a liquid crystal display, the film-coated transparent substrate 1 can prevent reflections of external light and suppress color change, thereby improving image quality or suppressing deterioration. Furthermore, since the film-coated transparent substrate 1 has high insulating properties, it can also be used in a display, for example, to provide touch panel functionality.

[0031] Hereinafter, each member of the film-coated transparent substrate 1 will be described in detail.

[0032] <Transparent substrate> The transparent substrate 2 has a substantially rectangular plate shape, although the shape of the transparent substrate 2 is not particularly limited and may have a substantially circular plate shape.

[0033] The transparent substrate 2 transmits light in the wavelength range of 400 nm to 700 nm. The transparent substrate 2 may be colored and transparent, but is preferably colorless and transparent from the viewpoint of further enhancing aesthetic appeal. In this specification, "transparent" means that the average light transmittance in the visible wavelength range of 400 nm to 700 nm is 80% or more. Furthermore, "colorless" means that the saturation of transmitted light when irradiated with a D65 light source is 2 or less.

[0034] In this embodiment, the transparent substrate 2 is made of glass, but the transparent substrate 2 may be made of other materials such as ceramics as long as it is a transparent substrate.

[0035] The glass constituting the transparent substrate 2 is preferably made of glass with a high glass transition temperature and low expansion, or low-expansion crystallized glass. The transparent substrate 2 may be made of borosilicate glass, alkali-free glass, aluminosilicate glass, or the like. A specific example of low-expansion crystallized glass is "N-0" manufactured by Nippon Electric Glass Co., Ltd., which is an LAS-based crystallized glass. In this case, the heat resistance of the transparent substrate 2 can be further improved, and the thermal expansion coefficient can be further reduced. Therefore, the transparent substrate 2 can be suitably used for applications such as a top plate for a cooker (hereinafter simply referred to as a "top plate") that is subjected to repeated heating and cooling.

[0036] There is no particular limitation on the thickness of the transparent substrate 2. The thickness of the transparent substrate 2 can be set appropriately depending on the light transmittance, etc. The thickness of the transparent substrate 2 can be, for example, about 0.035 mm to 5 mm.

[0037] <Anti-reflective film> The antireflection coating 3 is a multilayer film including a high-refractive-index film 5 having a relatively high refractive index and a low-refractive-index film 4 having a relatively low refractive index. As in this embodiment, the multilayer film constituting the antireflection coating 3 preferably has portions where the high-refractive-index films 5 and the low-refractive-index films 4 are alternately stacked. In this case, the reflectance of the film-coated transparent substrate 1 can be further reduced.

[0038] High refractive index film; In this embodiment, the high refractive index film 5 is made of niobium oxide and is a film containing niobium oxide as a main component. However, the high refractive index film 5 may also be a film containing niobium oxide, silicon nitride, tantalum oxide, titanium oxide, zirconium oxide, hafnium oxide, or aluminum oxide as a main component. These materials for the high refractive index film 5 may be used alone or in combination.

[0039] In this specification, a film containing a material as a main component refers to a film containing 50% by mass or more of the material. In a film containing a material as a main component, the material is preferably contained in an amount of 80% by mass or more, and more preferably 90% by mass or more. Of course, a film containing a material as a main component may also be a film containing 100% by mass of the material.

[0040] The thickness of each layer of the high refractive index film 5 is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more, and preferably 400 nm or less, more preferably 250 nm or less. In this case, the reflectance of the film-coated transparent substrate 1 can be further reduced.

[0041] The number of high refractive index films 5 in the antireflection film 3 is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and preferably 10 or less, more preferably 5 or less. In this case, the reflectance of the film-coated transparent substrate 1 can be further reduced.

[0042] low refractive index film; The low refractive index film 4 is a light absorbing film that includes a dielectric phase containing a material with a band gap of 2.0 eV or more and 2.7 eV or less, and a metal phase.

[0043] In a light-absorbing film, light absorption on the short wavelength side of visible light is carried out by light absorption due to the band gap of the dielectric phase, and light absorption on the long wavelength side is carried out by light absorption due to free electrons in the metallic phase. Therefore, when the low refractive index film 4 is a light-absorbing film, it can be made to be an achromatic color such as black.

[0044] In this embodiment, the dielectric phase is the matrix, and the metal phase is dispersed in the matrix of the dielectric phase. In this case, the insulating properties of the antireflection coating 3 can be further improved. However, the metal phase may be exposed on the surface of the dielectric phase. Alternatively, the dielectric phase and the metal phase may simply be mixed, and the form of the mixture is not particularly limited. As long as a conductive path is not formed by the metal phase throughout the entire light-absorbing film, the metal phases may be in partial contact with each other, and the size of the metal phases may not be uniform. Such a structure can be appropriately adjusted, for example, by changing the charge ratio of the materials constituting the dielectric phase and the metal phase.

[0045] The dielectric phase is preferably composed of a metal oxide having a band gap of 2.0 eV or more and 2.7 eV or less. However, the dielectric phase may be composed of a metal oxynitride or metal nitride having a band gap of 2.0 eV or more and 2.7 eV or less. The band gap can be calculated, for example, from a Tauc plot.

[0046] Examples of metal oxides with a band gap of 2.0 eV or more and 2.7 eV or less include Bi2O3 (2.5 eV), Fe2O3 (2.1 eV), Fe3O4 (2.0 eV), V2O5 (2.3 eV), WO3 (2.5 eV), MoO3 (2.7 eV), and Cr2O3 (2.6 eV). However, composite oxides containing these cations, such as BiVO4 (2.3 eV), may also be used. Examples of metal oxynitrides with a band gap of 2.0 eV or more and 2.7 eV or less include SrTaO2N, TiO 2-x Nx (X is, for example, 0.125).

[0047] The metal constituting the metal phase is not particularly limited, and examples thereof include Au, Ag, Cu, Pt, Pd, Rh, Zn, Fe, Sn, Ni, and Pb. The metal phase may also be composed of an alloy of these metals. Examples of the alloy include FeNi and CuNi.

[0048] In the light-absorbing film, the volume ratio of the metal phase (metal phase / (dielectric phase+metal phase)) is preferably 0.3 or more, more preferably 0.5 or more, and preferably 0.8 or less, more preferably 0.7 or less. When the volume ratio (metal phase / (dielectric phase+metal phase)) is equal to or greater than the lower limit, the insulating properties of the light-absorbing film 3 can be further improved. When the volume ratio (metal phase / (dielectric phase+metal phase)) is equal to or less than the upper limit, sufficient light absorption can be more reliably obtained at wavelengths where optical interference is likely to occur.

[0049] In the light-absorbing film, the volume ratio of the dielectric phase (dielectric phase / (dielectric phase+metal phase)) is preferably 0.2 or more, more preferably 0.3 or more, and preferably 0.7 or less, more preferably 0.5 or less. When the volume ratio (dielectric phase / (dielectric phase+metal phase)) is equal to or greater than the lower limit, sufficient light absorption ability can be more reliably obtained at wavelengths that are prone to optical interference. When the volume ratio (dielectric phase / (dielectric phase+metal phase)) is equal to or less than the upper limit, the insulating properties of the light-absorbing film 3 can be further improved.

[0050] In the present invention, the content of the material (metal) constituting the metal phase in the light-absorbing film (100% by mass) is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less. In this case, light can be absorbed more uniformly over almost the entire visible light range.

[0051] In the present invention, the content of the material constituting the dielectric phase in the light absorption film (in 100% by mass) is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less. In this case, the insulating property of the transparent substrate 1 with the film can be further enhanced.

[0052] As a preferable combination of the dielectric phase and the metal phase, there are a combination in which the dielectric phase is iron oxide and the metal phase is Ag, a combination in which the dielectric phase contains Al and Fe and the metal phase is Ag, and a combination in which the dielectric phase contains Ag, Fe, and Cr and the metal phase is Ag.

[0053] When the light absorption film contains Al and Fe in the dielectric phase, it is preferable to contain Ag, Al, and Fe in a molar ratio of Ag:Al:Fe = x:y:z (where x + y + z = 1, 0 < x < 1, 0 < y < 1, 0 ≤ z < 1). In this case, the change in color due to heating can be suppressed, and the aesthetic property of the transparent substrate 1 with the film can be further improved. Note that the light absorption film may further contain O.

[0054] Also, in this case, when 0 < z < 1, the light absorption film is a film containing Ag, aluminum oxide, and iron oxide. When z = 0, it is a film containing Ag and aluminum oxide.

[0055] Such a light absorption film can be formed, for example, using a mixed target of Ag, Al, and FeO in a sputtering method or a pulsed laser deposition method (PLD). Also, a mixed target of Ag and FeO and a target of Al may be used separately. Note that FeO may not be contained in each target.

[0056] Also, when the dielectric phase of the light absorption film contains Ag, Fe, and Cr, the change in color due to heating can be suppressed, and the aesthetic property of the transparent substrate 1 with the film can be further improved. Also, in addition to Ag, Fe, and Cr, it may further contain O.

[0057] Furthermore, the Ag content in the light-absorbing film is preferably 17% by mass or more, more preferably 30% by mass or more, and preferably 65% ​​by mass or less, more preferably 55% by mass or less. The Fe content in the light-absorbing film is preferably 25% by mass or more, more preferably 32% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less. The Cr content in the light-absorbing film is preferably 4% by mass or more, more preferably 8% by mass or more, and preferably 17% by mass or less, more preferably 12% by mass or less. The content of each metal in the light-absorbing film is the content of each metal relative to the total metal element content excluding oxygen in the light-absorbing film.

[0058] The mass ratio of Cr to Fe (Cr / Fe) in the light-absorbing film is preferably 0.10 or more, more preferably 0.20 or more, and preferably 0.60 or less, more preferably 0.40 or less, in which case the color of the light-absorbing film can be made even less susceptible to change due to heating.

[0059] The light-absorbing film may contain Ni, Mo, Cu, S, Mn, P, Si, and C, which are components contained in stainless steel. When the light-absorbing film contains Ni, the content is preferably 3 mass% or more, more preferably 6 mass% or more, and preferably 15 mass% or less, more preferably 12 mass% or less. However, the content of C in the light-absorbing film is preferably 1.2 mass% or less.

[0060] The light-absorbing film may further contain Al. In this case, it is possible to make it even more difficult for the color of the light-absorbing film to change due to heating. The content of Al in the light-absorbing film is preferably 2.5 mass % or more, more preferably 5 mass % or more, and preferably 35 mass % or less, more preferably 30 mass % or less. However, from the viewpoint of prioritizing the absorption coefficient of the film, the light-absorbing film may not substantially contain Al.

[0061] The contents of Ag, Fe, Ni, Cr, Al, etc. in the light-absorbing film can be measured by, for example, energy dispersive X-ray analysis, wavelength dispersive X-ray analysis, inductively coupled plasma mass spectrometry, etc.

[0062] In this case, the light absorbing film is specifically a film containing Ag, iron oxide, and chromium oxide.

[0063] Such a light-absorbing film can be formed by sputtering or pulsed laser deposition (PLD) using, for example, a mixed target of Ag and stainless steel. Alternatively, an Ag target and a stainless steel target may be used separately. Stainless steel is an alloy steel having an Fe content of 50% by mass or more, a Cr content of 10.5% by mass or more, and a C content of 1.2% by mass or less. Examples of stainless steel that can be used include SUS304, SUS301, and SUS316. When using a stainless steel target, the magnetic properties are lower than those of an Fe target, which stabilizes discharge and allows for more stable film formation. In particular, when using an austenitic stainless steel target, the discharge is stabilized and particularly stable film formation is possible because the target is nonmagnetic (paramagnetic).

[0064] The thickness of each light-absorbing film is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more, and preferably 500 nm or less, more preferably 300 nm or less. In this case, the light-absorbing ability of the film-coated transparent substrate 1 can be further improved, and the insulating properties can also be further improved.

[0065] The number of light-absorbing film layers in the antireflection film 3 is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and preferably 10 or less, more preferably 5 or less. In this case, the light-absorbing ability of the film-coated transparent substrate 1 can be further improved, and the insulating properties can also be further improved.

[0066] The refractive index of the light-absorbing film at a wavelength of 550 nm is preferably 1.0 or more, more preferably 1.2 or more, and preferably 2.2 or less, more preferably 2.0 or less. In this case, the light absorption ability of the film-coated transparent substrate 1 can be further improved, and the insulating properties can also be further improved. Note that the refractive index of the light-absorbing film can be adjusted by, for example, film formation conditions such as the target composition and film formation pressure.

[0067] The low refractive index film 4 may also include a low refractive index film different from the light absorbing film, although the low refractive index film 4 may also be entirely made of light absorbing films.

[0068] Examples of low refractive index films that are different from light absorbing films include films containing silicon oxide, aluminum oxide, magnesium fluoride, and barium fluoride as their main components.

[0069] The thickness of each layer of the low refractive index film 4 is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more, and preferably 500 nm or less, more preferably 300 nm or less. In this case, the reflectance of the film-coated transparent substrate 1 can be further reduced.

[0070] The total number of low refractive index films 4 in the antireflection film 3 is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and preferably 10 or less, more preferably 5 or less. In this case, the reflectance of the film-coated transparent substrate 1 can be further reduced.

[0071] outermost membrane; A silicon oxide film 6 can be provided as the outermost layer of the anti-reflection coating 3. The silicon oxide film 6 is a film containing silicon oxide as its main component. By providing the silicon oxide film 6 as the outermost layer, it is possible to further improve oxidation resistance, sulfidation resistance, weather resistance, and the like. Furthermore, the same effect can be obtained when silicon nitride is used instead of silicon oxide. Note that in the present invention, the silicon oxide film 6 or silicon nitride film does not necessarily have to be provided.

[0072] The thickness of each outermost layer is not particularly limited, but is preferably 20 nm or more, more preferably 50 nm or more, and is preferably 500 nm or less, more preferably 300 nm or less.

[0073] Anti-reflective coating; The total thickness of the antireflection film 3 is not particularly limited, but is preferably 100 nm or more, more preferably 200 nm or more, and is preferably 1000 nm or less, more preferably 800 nm or less.

[0074] The number of layers in the multilayer film constituting the antireflection film 3 is not particularly limited, but is preferably 2 or more, more preferably 4 or more, and is preferably 20 or less, more preferably 14 or less.

[0075] The anti-reflection film 3 is preferably a dielectric multilayer film having the above-described configuration. In this case, when the film-coated transparent substrate 1 is used in a display, the change in capacitance due to finger contact, which is necessary for a capacitive touch sensor, is maintained, allowing the touch panel to function. Therefore, the film-coated transparent substrate 1 can be more reliably provided with touch panel functionality.

[0076] When the antireflection coating 3 is a dielectric multilayer film, the electrical resistance of the antireflection coating 3 is preferably 10 6 Ω(10 6 Ω / □) or more, more preferably 10 7 Ω(10 7 Ω / □) or more, more preferably 10 8 Ω(10 8 Ω / □) or more, particularly preferably 10 9 Ω(10 9 When the electrical resistance value of the anti-reflection film 3 is equal to or greater than the above-mentioned lower limit, the touch panel function can be more reliably imparted to the film-coated transparent substrate 1. The upper limit of the electrical resistance value of the anti-reflection film 3 is, for example, 10 11 Ω(10 11The electrical resistance can be measured using methods specified in ASTM D257, JIS K 6271-1 (2008), JIS K 6271-2 (2008), K6911 (1995), etc.

[0077] The method for forming the high refractive index film 5, the low refractive index film 4, and the silicon oxide film 6 that constitute the antireflection film 3 is not particularly limited, but they can be formed by, for example, a physical vapor deposition method (PVD method), such as a sputtering method, a pulsed laser deposition method (PLD method), or an evaporation method.

[0078] <Transparent substrate with film> In the film-coated transparent substrate 1 of this embodiment, light is incident from the antireflection film 3 side. In this case, the luminous reflectance of the film-coated transparent substrate 1 is preferably 2% or less, more preferably 1% or less, and even more preferably 0.7% or less. In this case, the reflectance of the film-coated transparent substrate 1 can be further reduced. The lower limit of the luminous reflectance of the film-coated transparent substrate 1 is not particularly limited, but can be set to, for example, 0.1%. When light is incident from the transparent substrate 2 side, the luminous reflectance of the film-coated transparent substrate 1 is preferably 6% or less. In this case, the lower limit of the luminous reflectance of the film-coated transparent substrate 1 is also not particularly limited, but can be set to, for example, 0.1%.

[0079] The luminous transmittance of the film-coated transparent substrate 1 is preferably 75% or less, more preferably 70% or less, and even more preferably 65% ​​or less. In this case, the light absorption ability of the film-coated transparent substrate 1 can be further improved. The lower limit of the luminous transmittance of the film-coated transparent substrate 1 is not particularly limited, but can be, for example, 2%.

[0080] The luminous reflectance and luminous transmittance can be determined, for example, by using a spectrophotometer to measure the transmission spectrum and reflection spectrum from the anti-reflection film 3 side. At this time, the angle of incidence (AOI) is set to 0°. The measurement wavelength range is 380 nm to 780 nm.

[0081] In at least one of the luminous reflectance and the luminous transmittance of the film-coated transparent substrate 1, L * a * b * In the color system, a when the angle of incidence of light is 0° * The absolute value of the value is 5 or less, and b * The absolute value of this value is preferably equal to or less than 5. In this case, the reflected color and transmitted color of the film-coated transparent substrate 1 can be made even more neutral.

[0082] When the incident angle of light is 0°, * The absolute value of the value is preferably 4 or less, more preferably 2.5 or less. * The lower limit of the absolute value of the value is not particularly limited, but can be set to zero.

[0083] In addition, when the incident angle of light is 0°, * The absolute value of the value is preferably 4 or less, more preferably 2.5 or less. * The lower limit of the absolute value of the value is not particularly limited, but can be set to zero.

[0084] In addition, at least one of the luminous reflectance and the luminous transmittance of the film-coated transparent substrate 1 is L * a * b * In the color system, L when the angle of incidence of light is 0° * The absolute value of the value is, for example, 1 or more and 20 or less.

[0085] In addition, at least one of the luminous reflectance and the luminous transmittance of the film-coated transparent substrate 1 is L * a * b * In the color system, a when the angle of incidence of light is 0° * value and a when the incident angle of light is 45° * The absolute value of the difference between the values ​​is 5 or less, and the incident angle of light is 0°. * value and b when the incident angle of light is 45° *It is preferable that the absolute value of the difference from the value is not more than 5. In this case, color shift due to the angle of incidence of light can be made even less likely to occur.

[0086] When the incident angle of light is 0°, * value and a when the incident angle of light is 45° * The absolute value of the difference between the values ​​is preferably 4 or less, and more preferably 2.5 or less. * value and a when the incident angle of light is 45° * The lower limit of the absolute value of the difference from the value is not particularly limited, but can be set to 0, for example.

[0087] Also, when the incident angle of light is 0°, * value and b when the incident angle of light is 45° * The absolute value of the difference between the values ​​is preferably 4 or less, and more preferably 2.5 or less. * value and b when the incident angle of light is 45° * The lower limit of the absolute value of the difference from the value is not particularly limited, but can be set to 0, for example.

[0088] In addition, the above L * value, a * value, and b * The value can be obtained, for example, as follows. First, a spectrophotometer is used to measure the transmission spectrum and reflection spectrum from the anti-reflection film 3 side. At this time, the angle of incidence (AOI) is set to 0° and 45°, and the measurement wavelength range is set to 380 nm to 780 nm. From the obtained transmittance spectrum and reflectance spectrum, the lightness (L * ), chromaticity (a * and b * ) can be obtained.

[0089] (Second to fourth embodiments) Fig. 2 is a schematic cross-sectional view showing a film-coated transparent substrate according to a second embodiment of the present invention. As shown in Fig. 2, in a film-coated transparent substrate 21, five high-refractive-index films 5 and low-refractive-index films 4 are alternately stacked on a first main surface 2a of a glass substrate 2 in order from the high-refractive-index film 5. In addition, a silicon oxide film 6 is provided as the outermost layer on the high-refractive-index film 5, thereby forming an anti-reflection film 23. The other points are the same as those of the first embodiment.

[0090] As in the second embodiment, the high refractive index film 5 may be laminated on the first main surface 2a of the glass substrate 2. In addition, when a silicon oxide film 6 is provided as the outermost layer on the high refractive index film 5, the silicon oxide film 6 can also serve as the low refractive index film 4.

[0091] Fig. 3 is a schematic cross-sectional view showing a film-coated transparent substrate according to a third embodiment of the present invention. As shown in Fig. 3, in a film-coated transparent substrate 31, five high-refractive-index films 5 and low-refractive-index films 4 are alternately stacked on the second main surface 2b of a glass substrate 2 in order from the high-refractive-index film 5. In addition, a silicon oxide film 6 is provided as the outermost layer on the high-refractive-index film 5, thereby forming an anti-reflection film 33. Other points are the same as those of the first embodiment.

[0092] 4 is a schematic cross-sectional view showing a film-coated transparent substrate according to a fourth embodiment of the present invention. As shown in FIG. 4, in a film-coated transparent substrate 41, five high-refractive-index films 5 and low-refractive-index films 4 are alternately stacked on the second main surface 2b of a glass substrate 2 in order from the high-refractive-index film 5. This constitutes an anti-reflection film 43. In the anti-reflection film 43, a silicon oxide film 6 is not provided as the outermost layer on the high-refractive-index film 5. The other points are the same as those in the first embodiment.

[0093] In the first and second embodiments, anti-reflection films 3, 23 are provided on the first main surface 2a of the transparent substrate 2, whereas in the third and fourth embodiments, anti-reflection films 33, 43 are provided on the second main surface 2b of the transparent substrate 2.

[0094] Therefore, in the third and fourth embodiments, when measuring the luminous reflectance and luminous transmittance described in the first embodiment, the transmission spectrum and reflection spectrum are measured from the first main surface 2a side of the transparent substrate 2 (the side opposite to the antireflection films 33, 43).

[0095] Furthermore, when the silicon oxide film 6 is not provided as the outermost layer as in the fourth embodiment, it is preferable to provide a silicon nitride film as the outermost high refractive index film 5. In this case, it is possible to further improve oxidation resistance, sulfidation resistance, weather resistance, and the like.

[0096] In addition, like the film-coated transparent substrate 1, the film-coated transparent substrates 21, 31, and 41 of the second to fourth embodiments have excellent light absorption ability, neutral reflected and transmitted colors, are less likely to undergo color shift depending on the angle of incidence of light, and are also insulating.

[0097] [Cooking appliance top plate] 5 is a schematic cross-sectional view showing a top plate for a cooker according to one embodiment of the present invention. As shown in FIG. 5, a top plate 51 for a cooker includes a transparent substrate 1 with a film.

[0098] In the top plate 51 for a cooker, the second main surface 2b of the transparent substrate 2 constituting the film-coated transparent substrate 1 is the cooking surface. On the other hand, the first main surface 2a of the transparent substrate 2 constituting the film-coated transparent substrate 1 is the back surface. The cooking surface is the surface on which cooking utensils such as pots and frying pans are placed. The back surface is the surface facing the light source 52 such as an LED or a display and the heating device inside the cooker. Therefore, the cooking surface and the back surface are in a front-back relationship. In this embodiment, the transparent substrate 2 is made of low-expansion crystallized glass.

[0099] An anti-reflection film 3 is provided on the back surface (first main surface 2a) of the transparent substrate 2. A heat-resistant resin layer 53 is provided on the anti-reflection film 3. The heat-resistant resin layer 53 may be provided between the transparent substrate 2 and the anti-reflection film 3. In this embodiment, in plan view, the area where the heat-resistant resin layer 53 is not provided is defined as a display area A. In plan view, the area where the heat-resistant resin layer 53 is provided is defined as a non-display area B.

[0100] The heat-resistant resin layer 53 is a light-blocking layer. Therefore, by providing the heat-resistant resin layer 53, the concealment of the internal structure of the cooking appliance can be further improved. The heat-resistant resin layer 53 can be composed of a heat-resistant resin such as silicone resin and a coloring pigment, etc. Note that the heat-resistant resin layer 53 does not necessarily have to be provided.

[0101] A light source 52 such as a display or an LED is provided below the film-coated transparent substrate 1. The light source 52 is a member provided to display information in the display area A. The information displayed in the display area A is not particularly limited, and examples include information indicating the state of the cooker, such as whether the power is on or heating, and information such as time.

[0102] In the display area A, light from the light source 52 passes through the anti-reflection film 3 and the transparent substrate 2 in this order before being emitted to the outside. In the non-display area B, the light from the light source 52 is blocked by the heat-resistant resin layer 53. Therefore, in the display area A, by transmitting the light from the light source 52, it is possible to display letters, numbers, symbols, etc.

[0103] The top plate 51 for a cooking appliance includes a film-coated transparent substrate 1. Therefore, when the light source 52 is turned on, various pieces of information can be clearly seen, and when the light source 52 is turned off, the appearance is excellent. Furthermore, the boundary between the display area A and the non-display area B can be made difficult to see while concealing the internal structure of the cooking appliance. In addition, the internal structure of the cooking appliance can be reliably concealed regardless of the angle from which the top plate 51 for a cooking appliance is viewed. A display with a touch panel function may be built inside the cooking appliance. In this case, the color of the display is less likely to change regardless of the viewing angle, and visibility can be maintained.

[0104] [Window glass for cooking appliances] Furthermore, the above-mentioned cooking appliance top plate 51 may be used as a cooking appliance windowpane for use in a cooking appliance such as a microwave oven or an oven. In this case, the second main surface 2b of the transparent substrate 2 constituting the above-mentioned film-coated transparent substrate 1 can be the main surface opposite to the heating device side of the cooking appliance, and the first main surface 2a of the transparent substrate 2 constituting the film-coated transparent substrate 1 can be the main surface on the heating device side of the cooking appliance.

[0105] [Cover glass] Fig. 6 is a schematic cross-sectional view showing a cover glass according to one embodiment of the present invention. As shown in Fig. 6, the cover glass 61 includes a film-coated transparent substrate 31. The cover glass 61 is a cover glass that is used, for example, by being placed in front of a display.

[0106] In the cover glass 61, the second main surface 2b of the transparent substrate 2 constituting the film-coated transparent substrate 31 is the main surface disposed on the outside. On the other hand, the first main surface 2a of the transparent substrate 2 constituting the film-coated transparent substrate 31 is the main surface on the display side. Therefore, in the cover glass 61, an anti-reflection film 33 is provided on the main surface 2b of the transparent substrate 2 opposite to the side on which the display is provided.

[0107] The cover glass 61 includes a film-coated transparent substrate 31. Therefore, when the cover glass 61 is used in a display such as a liquid crystal display, it is possible to improve image quality by preventing reflection of external light, etc. Furthermore, since the cover glass 61 has high insulating properties, it is also possible to provide a touch panel function when used in a display.

[0108] The present invention will be described in more detail below with reference to examples. However, the following examples are merely illustrative and are not intended to limit the scope of the present invention.

[0109] Examples 1 to 6 A dielectric multilayer film was fabricated by sputtering on the first principal surface of a transparent glass substrate (manufactured by Nippon Electric Glass Co., Ltd., product name "OA-10G," thickness: 0.5 mm, refractive index: 1.52). Specifically, the antireflection film was fabricated on the glass substrate with the composition and film thicknesses shown in Table 1 below, by alternately stacking a light-absorbing film (Ag-SUS-O, refractive index = 1.56, extinction coefficient = 1.21), a niobium oxide film (NbO, refractive index = 2.29, extinction coefficient = 0), an Ag-SUS-O film, an NbO film, and a silicon oxide film (SiO, refractive index = 1.46, extinction coefficient = 0) in this order. This resulted in a film-coated transparent substrate. Note that in the examples and comparative examples, the refractive indexes and extinction coefficients are all at a wavelength of 550 nm. The electrical resistance of the antireflection film was measured by a direct current two-terminal method using platinum electrodes.

[0110] The Ag-SUS-O film serving as the light-absorbing film was formed by sputtering using a mixed target of Ag and stainless steel (SUS304). The Ag content in the mixed target was 32.6 mass %, and the stainless steel content was 67.4 mass %. The substrate temperature was 250°C, and the oxygen partial pressure was 0.03 Pa. The metal element contents excluding oxygen in the light-absorbing film were 48.022 mass %, 32.782 mass %, and 10.615 mass % for Ag, Fe, and Cr, respectively. Each composition was measured using an electron probe microanalyzer (EPMA, manufactured by JEOL Ltd., product number "JXA-8100").

[0111] [Table 1]

[0112] (Examples 7 to 16 and Comparative Examples 1 and 2) A film-coated transparent substrate was obtained in the same manner as in Example 1, except that an antireflection film was formed on the first main surface of the glass substrate with the configuration and thickness (film thickness) shown in the following Tables 2 and 3. Tables 2 and 3 show that each film was formed in order from bottom to top on the first main surface of the glass substrate.

[0113] In Examples 7 to 9, a silicon nitride film (SiN film, refractive index = 1.99, extinction coefficient = 0) was formed as the high refractive index film instead of an Nb2O5 film. In Examples 10 to 12, an Ag-Fe-O film (refractive index = 1.70, extinction coefficient = 1.39) was used as the light absorbing film instead of an Ag-SUS-O film. In Examples 13 and 14, an Ag-Fe-O film and an SiN film were used. In Example 15, an Ag-Al-Fe-O film (refractive index = 1.18, extinction coefficient = 1.49) was used as the light absorbing film instead of an Ag-SUS-O film. In Example 16, an Ag-Al-Fe-O film and an SiN film were used. In Comparative Example 1, a SiO2 film and a niobium nitride film (NbN, refractive index = 2.96, extinction coefficient = 0.47), which is a conductor, were used as the light absorbing film. In Comparative Example 2, a SiO2 film and a titanium nitride film (TiN, refractive index=1.20, extinction coefficient=1.71) which is a conductor were used as the light absorbing film.

[0114] The Ag-Fe-O film serving as the light-absorbing film was formed by sputtering using a mixed target of Ag and FeO. The Ag content in the mixed target was 32.6 mass %. The substrate temperature was 250°C, and the oxygen partial pressure was 0.025 Pa. The Ag content in the metal element content excluding oxygen in the light-absorbing film was 58.1 mass %, and the Fe content was 41.9 mass %.

[0115] The Ag-Al-Fe-O film serving as the light-absorbing film was formed by sputtering using a mixed target of Ag, Al, and FeO. The Ag content in the mixed target was 60 mol %. The substrate temperature was 300°C, and the oxygen partial pressure was 0.5 Pa. The metal element contents excluding oxygen in the light-absorbing film were 88 mol % for Ag, 10 mol % for Fe, and 2 mol % for Al. The molar ratio of Al to the total of Al and Fe (y / (y+z)) (Al / (Al+Fe)) was 0.14. The compositions of Ag, Al, and Fe were measured by inductively coupled plasma mass spectrometry.

[0116] [Table 2]

[0117] [Table 3]

[0118] [evaluation] The transmission spectrum and reflection spectrum of the obtained film-coated transparent substrate were measured from the film-formed surface side using a spectrophotometer (Hitachi High-Tech Science Corporation, product number "U-4100"). Specifically, the angles of incidence (AOI) were set to 0°, 15°, 30°, and 45°, and the measurement wavelength range was 380 nm to 780 nm. From the obtained transmittance spectrum and reflectance spectrum, the luminous reflectance, luminous transmittance, and lightness (L) of reflected light and transmitted light when irradiated with a D65 light source were determined. * ), chromaticity (a * and b * ) was determined. In each table, the luminous reflectance and luminous transmittance are indicated by Y. The measurement of the luminous reflectance does not include reflection from the rear surface of the glass substrate.

[0119] The results are shown in Tables 4 to 8 below.

[0120] [Table 4]

[0121] [Table 5]

[0122] [Table 6]

[0123] [Table 7]

[0124] [Table 8]

[0125] (Examples 17 to 25) Film-coated transparent substrates were obtained in the same manner as in Examples 1 to 16, except that dielectric multilayer films were formed on the second main surface of the glass substrate with the configurations and thicknesses (film thicknesses) shown in the following Tables 9 and 10. Tables 9 and 10 show that each film was formed on the second main surface of the glass substrate in the order listed from top to bottom.

[0126] [Table 9]

[0127] [Table 10]

[0128] [evaluation] The transmission spectrum and reflection spectrum of the obtained film-coated transparent substrate were measured from the main surface of the glass substrate opposite to the film-formed surface using a spectrophotometer (Hitachi High-Tech Science Corporation, model number "U-4100"). Specifically, the angles of incidence (AOI) were set to 0°, 15°, 30°, and 45°, and the measurement wavelength range was 380 nm to 780 nm. From the obtained transmittance spectrum and reflectance spectrum, the luminous reflectance, luminous transmittance, and lightness (L) of reflected light and transmitted light when irradiated with a D65 light source were determined. * ), chromaticity (a * and b * In each table, the luminous reflectance and luminous transmittance are indicated by Y.

[0129] The results are shown in Tables 11 to 13 below.

[0130] [Table 11]

[0131] [Table 12]

[0132] [Table 13]

[0133] From the above, the film-coated transparent substrates of Examples 1 to 25 have low reflectance, have light absorption properties (transmittance of 75% or less), and when the incident angle of light is 0°, both the reflected color and the transmitted color are neutral (in at least one of the luminous reflectance and the luminous transmittance, |a * |≦5, |b * |≦5), and can be given touch panel function (electrical resistance ≧ 10 6 Ω), and it was confirmed that color shift was unlikely to occur at incident angles of 0° and 45° (in at least one of the luminous reflectance and luminous transmittance, |a * |≦5, |b * |≦5). [Explanation of symbols]

[0134] 1, 21, 31, 41...Transparent substrate with film 2...Transparent substrate 2a...first principal surface 2b...Second main surface 3,23,33,43…Anti-reflection coating 4...Low refractive index film 5...High refractive index film 6...Silicon oxide film 51...Cooker top plate 52...Light source 53...Heat-resistant resin layer 61...Cover glass

Claims

1. A transparent substrate; an anti-reflection film provided on one main surface of the transparent substrate; Equipped with the antireflection film is a multilayer film including a high-refractive-index film having a relatively high refractive index and a low-refractive-index film having a relatively low refractive index, In the multilayer film, the high refractive index films and the low refractive index films are alternately stacked, At least one layer of the low refractive index film is a light absorbing film, The light absorbing film comprises a dielectric phase containing a material having a band gap of 2.0 eV or more and 2.7 eV or less, and a metal phase.

2. 2. The film-coated transparent substrate according to claim 1, wherein the refractive index of the light-absorbing film at a wavelength of 550 nm is 1.0 or more and 2.2 or less.

3. 3. The film-coated transparent substrate according to claim 1, wherein at least one layer of the high refractive index film is at least one selected from the group consisting of niobium oxide, silicon nitride, tantalum oxide, titanium oxide, zirconium oxide, hafnium oxide, and aluminum oxide.

4. 4. The film-coated transparent substrate according to claim 1, wherein the outermost layer of the multilayer film on the side opposite to the transparent substrate is a film containing silicon oxide or silicon nitride.

5. 5. The film-attached transparent substrate according to claim 1, wherein the material having a band gap of 2.0 eV or more and 2.7 eV or less is a metal oxide.

6. The electrical resistance of the anti-reflection film is 10 ６ The film-attached transparent substrate according to any one of claims 1 to 5, having a resistance of Ω or more.

7. 7. The film-coated transparent substrate according to claim 1, wherein the film-coated transparent substrate has a luminous reflectance of 2% or less when light is incident from the antireflection film side.

8. 8. The film-coated transparent substrate according to claim 1, wherein the film-coated transparent substrate has a luminous reflectance of 6% or less when light is incident from the transparent substrate side.

9. 9. The film-coated transparent substrate according to claim 1, wherein the film-coated transparent substrate has a luminous transmittance of 75% or less.

10. In at least one of the luminous reflectance and the luminous transmittance of the film-coated transparent substrate, L ＊ a ＊ b ＊ In the color system, a when the angle of incidence of light is 0° ＊ The absolute value of the value is 5 or less, and b ＊ The film-attached transparent substrate according to any one of claims 1 to 9, wherein the absolute value of the value is 5 or less.

11. In at least one of the luminous reflectance and the luminous transmittance of the film-coated transparent substrate, L ＊ a ＊ b ＊ In the color system, a when the angle of incidence of light is 0° ＊ value and a when the incident angle of light is 45° ＊ When the absolute value of the difference from the value is 5 or less and the incident angle of light is 0°, ＊ value and b when the incident angle of light is 45° ＊ 11. The film-attached transparent substrate according to claim 1, wherein the absolute value of the difference between the values ​​is 5 or less.

12. A transparent substrate with a film according to any one of claims 1 to 11 is provided, The transparent substrate has a cooking surface on which a cooking utensil is placed and a back surface opposite to the cooking surface, and the anti-reflection film is disposed on the back surface of the transparent substrate.

13. A window glass used in a cooking appliance, A transparent substrate with a film according to any one of claims 1 to 11 is provided, A windowpane for a cooking appliance, wherein the light-absorbing film is disposed on a main surface of the transparent substrate on the heating device side of the cooking appliance.

14. A cover glass for use in a display, comprising: A transparent substrate with a film according to any one of claims 1 to 11 is provided, the transparent substrate is a front substrate, a cover glass, the anti-reflection film being disposed on a main surface of the transparent substrate opposite to a surface on which a display is provided;

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