Smart window

Abstract

The present invention relates to a smart window comprising: a first glass plate; a dielectric layer formed on the first glass plate; an infrared reflective coating layer formed on the dielectric layer and including a metal layer and a metal protective layer; an anti-haze layer formed on the infrared reflective coating layer and containing a metal oxide; a transmittance-variable layer formed on the anti-haze layer and containing an organic material; a second glass plate formed on the transmittance-variable layer; and an anti-reflection layer formed on the second glass plate and containing an inorganic material.

Description

Smart Window

[0001] The present invention relates to a smart window having excellent durability, appropriate visible light transmittance to ensure an external view, and adjustable light transmittance.

[0002] Recently, the use of functional films in architectural and automotive glass is increasing. This allows for freely adjusting the transmittance of external sunlight, reducing energy loss and improving energy efficiency, thereby providing a more comfortable environment for users. These functional films lower sunlight transmittance, preventing external heat from entering a building. Furthermore, by increasing sunlight transmittance, they enhance the sense of openness and allow external heat to enter the building.

[0003] These transmittance-variable films typically contain organic materials, and include suspended particle devices (SPDs), polymer dispersed liquid crystal (PDLC) methods, and electrochromic (EC) methods. In addition, transmittance-variable films typically electrically control the transmittance of sunlight depending on the orientation of organic polymer materials. Specifically, the SPD and PDLC methods position chromic elements with a transmittance-variable function between a pair of transparent electrodes, and control light transmittance through the dynamic behavior of the chromic elements. In addition, the EC method controls light transmittance by using elements that change color by utilizing the principle of oxidation and / or reduction due to the flow of current. For example, Japanese Patent Laid-Open No. 2017-186179 (Patent Document 1) discloses a laminated glass comprising a pair of opposing glass plates, a pair of intermediate adhesive layers arranged across the entire surfaces corresponding to the opposing surfaces between the pair of glass plates, and a functional film arranged between the pair of intermediate adhesive layers so as to be in contact with the opposing surfaces of each intermediate adhesive layer. However, a conventional variable transmittance film including an organic material, such as the laminated glass of Patent Document 1, has a problem in that the organic material may have its structure deformed by ultraviolet or infrared rays in sunlight when applied outdoors for a long period of time, which leads to a deterioration in the transmittance controllability, which is a major performance of the film.

[0004] Therefore, there is a need for research and development on smart windows that are durable enough to withstand long-term exposure to harsh environments without problems such as a decline in transmittance control, have appropriate visible light transmittance to ensure an outside view, and have easy light transmittance control.

[0005] [Prior Art Literature]

[0006] [Patent Document]

[0007] (Patent Document 1) Japanese Patent Publication No. 2017-186179 (Published: October 12, 2017)

[0008] Accordingly, the present invention aims to provide a smart window that has excellent durability, does not cause problems such as a decrease in transmittance controllability even when exposed to a harsh environment for a long period of time, has an appropriate visible light transmittance to ensure an external view, and has easy light transmittance control.

[0009] [1] The present invention comprises: a first glass plate;

[0010] A dielectric layer formed on the first glass plate;

[0011] An infrared reflective coating layer formed on the dielectric layer and including a metal layer and a metal protective layer;

[0012] An anti-fog layer formed on the infrared reflective coating layer and containing a metal oxide;

[0013] A transmittance variable layer formed on the above anti-fog layer and containing an organic material;

[0014] A second glass plate formed on the above-mentioned transmittance variable layer; and

[0015] A smart window is provided, comprising an anti-reflection layer formed on the second glass plate and containing an inorganic material.

[0016] [2] In the present invention, in the above [1], the metal layer includes at least one selected from the group consisting of silver (Ag), gold (Au) and copper (Cu),

[0017] The above metal protective layer provides a smart window comprising at least one selected from the group consisting of nickel (Ni) and chromium (Cr), or a nitride or oxide thereof.

[0018] [3] In the present invention, in the above [1] or [2], the anti-fog layer includes a zinc (Zn)-based oxide,

[0019] The above dielectric layer provides a smart window comprising a silicon-containing nitride or a silicon-containing nitride.

[0020] [4] The present invention provides a smart window in any one of the above [1] to [3], wherein the anti-reflection layer includes at least one inorganic material selected from the group consisting of indium tin oxide (ITO), antimony zinc oxide (AZO), antimony tin oxide (ATO), and tin oxide.

[0021] [5] The present invention is characterized in that, in any one of [1] to [4], the dielectric layer has an average thickness of 10 to 60 nm,

[0022] The above infrared reflective coating layer has an average thickness of 5.1 to 40.0 nm,

[0023] The above anti-fog layer has an average thickness of 1 to 10 nm,

[0024] The above anti-reflective coating layer provides a smart window having an average thickness of 150 to 450 nm.

[0025] The smart window according to the present invention exhibits excellent durability, preventing degradation of transmittance controllability even after prolonged exposure to harsh environments. Furthermore, it boasts an appropriate visible light transmittance, ensuring an external view, and allows for easy light transmittance control. Accordingly, the smart window is highly suitable as a building material for residential and non-residential buildings, as well as for use in various fields, including vehicles.

[0026] FIG. 1 is a cross-sectional view of a smart window according to one embodiment of the present invention.

[0027] The present invention is described in detail below.

[0028] In the present invention, when it is said that a member is located “on” another member, this includes not only a case where a member is in contact with another member, but also a case where another member exists between the two members.

[0029] A smart window according to the present invention includes a first glass plate, a dielectric layer, an infrared reflective coating layer, an anti-fog layer, a transmittance variable layer, a second glass plate, and an anti-reflection layer, wherein the infrared reflective coating layer includes a metal layer and a metal protective layer.

[0030] Referring to FIG. 1, the smart window (10) includes a first glass plate (100), a dielectric layer (200), an infrared reflective coating layer (300), an anti-fog layer (400), a transmittance variable layer (500), a second glass plate (600), and an anti-reflection layer (700) laminated in sequence, and the infrared reflective coating layer (300) may include a metal layer (310) and a metal protective layer (320) laminated in sequence.

[0031] The smart window according to the present invention has the advantage of excellent durability by including an infrared reflective coating layer on a transmittance variable layer containing an organic material as described above, thereby protecting the organic material in the transmittance variable layer from infrared (IR) and ultraviolet (UV) rays of an external light source, thereby preventing problems such as a decrease in transmittance controllability even when exposed to a harsh environment for a long period of time. In addition, the smart window has the advantage of ensuring an external view by including an anti-reflection coating layer, thereby preventing the problem of visible light reflectance increasing depending on a person's position.

[0032] First glass plate and second glass plate

[0033] The first glass plate can be ordinary glass such as soda lime glass used for construction or automobiles.

[0034] Each of the first glass plate and the second glass plate may use glass of an appropriate thickness depending on the intended use. For example, the first glass plate and the second glass plate may each independently have an average thickness of 1.0 to 2.5 mm, or 1.0 to 2.1 mm. If the average thickness of the first glass plate and the second glass plate is less than the above range, there is a risk that the manufactured window may be damaged by external impact, and if it exceeds the above range, the weight of the manufactured window may increase, which may result in a decrease in the fuel efficiency of a vehicle including the window.

[0035] In addition, the first glass plate and the second glass plate may each independently additionally include a dye coating layer. In this case, the dye coating layer may be formed on the surface of the first glass plate that contacts the infrared reflective coating layer, and the dye coating layer may be formed on the surface of the second glass plate that contacts the anti-reflection layer. In addition, the dye coating layer may use any dye that can be commonly applied to glass plates without particular limitations, and may include, for example, a black inorganic dye.

[0036] dielectric layer

[0037] The dielectric layer protects the infrared-reflecting metal layer from ions or oxygen during heat treatment and plays a role in controlling the optical properties of the manufactured glass.

[0038] The dielectric layer may include a silicon-containing nitride or a silicon-containing nitride. Specifically, the dielectric layer may include Si x N y O z , wherein x may be 1 to 3, y may be 1 to 4, and z may be 0 to 4. More specifically, the dielectric layer may include Si3N4.

[0039] In addition, the dielectric layer may have a refractive index of 1.5 to 2.5, or 1.8 to 2.5. Furthermore, the dielectric layer may have an absorption coefficient of 0.1 or less, or 0 to 0.1. When the refractive index and / or absorption coefficient of the dielectric layer are within the above ranges, the problem of reduced visible light transmittance of the manufactured glass can be prevented.

[0040] The dielectric layer may have an average thickness of 10 to 60 nm, 10 to 55 nm, or 15 to 40 nm. If the thickness of the dielectric layer is less than the above range, the durability of the manufactured glass may be reduced, and if it exceeds the range, the optical performance of the manufactured glass may be insufficient.

[0041] infrared reflective coating layer

[0042] The infrared reflective coating layer selectively transmits and reflects solar radiation.

[0043] The above infrared reflective coating layer includes a metal layer and a metal protective layer.

[0044] The above infrared reflective coating layer may have an average thickness of 5.1 to 40.0 nm, or 8.0 to 20.0 nm. At this time, the metal layer and the metal protective layer may have a thickness ratio of 0.5:1 to 100:1, 1:1 to 30:1, or 1.5:1 to 15:1. If the thickness ratio of the metal layer and the metal protective layer is less than the above range, that is, if the metal layer is thinner than the thickness of the metal protective layer, there is a problem that the infrared reflectivity of the manufactured product is insufficient, and if it exceeds the above range, that is, if the metal protective layer is thinner than the thickness of the metal layer, the metal layer may be damaged by heat during high-temperature molding, which may cause a problem that productivity may decrease.

[0045] <Metal layer>

[0046] The above metal layer serves to selectively transmit and reflect solar radiation.

[0047] Additionally, the metal layer may include at least one selected from the group consisting of silver (Ag), gold (Au), and copper (Cu). Specifically, the metal layer may include silver (Ag).

[0048] When the metal layer includes silver (Ag), other metal elements may be added to improve durability. However, care must be taken because if the amount added is excessive, the low-emission performance may deteriorate. More specifically, the metal layer may be doped with 0.5 to 5 wt% of an additional metal selected from the group consisting of nickel (Ni), lead (Pd), platinum (Pt), copper (Cu), and gold (Au), and may include silver (Ag). When the content of the additional metal doped into silver (Ag) in the metal layer is less than the above range, the durability of the manufactured glass is insufficient, and when it exceeds the above range, the performance of reflecting the infrared region of the manufactured glass may deteriorate.

[0049] In addition, the metal layer may have an average thickness of 5 to 30 nm, or 7 to 15 nm. If the average thickness of the metal layer is less than the above range, there is a problem of insufficient low-emission performance of the manufactured glass, and if it exceeds the above range, the visible light reflectance of the manufactured glass may become excessively high, thereby reducing the sense of openness.

[0050] <Metal protective layer>

[0051] The above metal protective layer acts as a barrier that prevents the movement of Na and O2 in the air that diffuse from the glass during heat treatment such as strengthening or bending, and absorbs O2 that penetrates into the metal layer.

[0052] In addition, the metal protective layer may include at least one selected from the group consisting of nickel (Ni) and chromium (Cr), or a nitride or oxide thereof. Specifically, the metal protective layer may include at least one selected from the group consisting of nickel (Ni), chromium (Cr), and a nickel (Ni)-chromium (Cr) alloy. In this case, the nickel (Ni)-chromium (Cr) alloy may have a weight ratio of Ni to Cr of 9:1 to 7:3, or 8.5:1.5 to 7.5:2.5.

[0053] The above metal protective layer may be a single layer or multiple layers. In this case, if the metal protective layer is multiple layers, it may include a form in which a first metal protective layer and a second metal protective layer are sequentially laminated on the metal layer. That is, if the metal protective layer is multiple layers, it may include a form in which the metal protective layer is laminated in multiple layers.

[0054] In addition, the metal protective layer may have an average thickness of 0.1 to 10.0 nm, 0.5 to 7.0 mm, or 1.0 to 5.0 nm. When the average thickness of the metal protective layer is within the above range, it is preferable in terms of improvement of fogging phenomenon after heat treatment and visible light transmittance. On the other hand, when the average thickness of the metal protective layer is less than the above range, there is a problem that the durability of the manufactured window is lowered, and when it exceeds the above range, the transmittance of the manufactured window is lowered, which may cause fogging.

[0055] anti-fog layer

[0056] The anti-fog layer suppresses the agglomeration or haze phenomenon of the infrared reflective coating layer due to high heat during heat treatment. In addition, when the manufactured glass is heat treated at a high temperature of 600℃ or higher, the O2 in the anti-fog layer diffuses into the metal protective layer, thereby oxidizing the metal elements in the metal protective layer, thereby increasing the visible light transmittance after the heat treatment. In addition, the anti-fog layer helps stabilize the metal layer, thereby suppressing the metal layer from diffusing into the dielectric layer during heat treatment and the occurrence of optical defects such as agglomeration, thereby preventing hazing of the manufactured glass.

[0057] In addition, the anti-fog layer includes a metal oxide. For example, the anti-fog layer may include a zinc (Zn)-based oxide. Specifically, the anti-fog layer may include a zinc (Zn)-based oxide further including at least one element selected from the group consisting of Sn, Nb, Al, Sb, Mo, Cr, Ti, and Ni. More specifically, the anti-fog layer may include a Zn-based oxide including at least one element selected from the group consisting of Sn and Al. Even more specifically, the flow-preventing layer may include an oxide of a tin (Sn)-aluminum (Al)-zinc (Zn) alloy.

[0058] The above anti-fog layer may have an average thickness of 1 to 10 nm, 2 to 8 nm, or 5 to 8 nm. If the average thickness of the anti-fog layer is less than the above range, there may be a problem of the light transmittance of the manufactured glass being reduced, and if it exceeds the above range, there may be a problem of increased fogging in the manufactured glass during heat treatment.

[0059] Transmittance variable layer

[0060] The transmittance variable layer adjusts the transmittance to sunlight to reduce energy loss and improve energy efficiency.

[0061] The above-mentioned transmittance variable layer comprises an organic material. Specifically, the transmittance variable layer may comprise a suspended particle device (SPD) or polymer dispersed liquid crystal (PDLC) composed of an organic material. In this case, the SPD or PDLC may be used without any special restrictions as long as it is applied as a conventional variable film.

[0062] In addition, the average thickness of the variable transmittance layer may be 50 to 300 μm, or 100 to 200 μm. If the average thickness of the variable transmittance layer is less than the above range, there is a problem that bubbles are generated due to internal steps, resulting in poor appearance of the manufactured glass. If it exceeds the above range, there may be a problem that the glass is broken due to increased load and pressure caused by the increased thickness during the manufacture of laminated glass.

[0063] anti-reflection layer

[0064] The antireflection layer serves to prevent reflection of light in the visible light range, i.e., light with a wavelength of 380 to 780 nm.

[0065] The antireflection layer may have a refractive index between, for example, the refractive index of the substrate (typically about 1.52 for glass) and the refractive index of air (1.00), and may be a film composed of a single component. That is, the antireflection layer may have a refractive index of 1.00 to 1.52, or 1.10 to 1.50.

[0066] The above anti-reflection layer includes an inorganic material. Specifically, the anti-reflection layer may include at least one inorganic material selected from the group consisting of indium tin oxide (ITO), antimony zinc oxide (AZO), antimony tin oxide (ATO), and tin oxide.

[0067] In addition, the average thickness of the anti-reflection layer may be 150 to 450 nm, or 200 to 400 nm. If the thickness of the anti-reflection layer is less than the above range, the formation of the anti-reflection layer is not performed normally, which may result in a problem of insufficient anti-reflection performance of the manufactured glass. If the thickness exceeds the above range, the reflectivity of the manufactured glass may increase, which may prevent a problem of deterioration of the color of the glass surface.

[0068] The above smart window may additionally include an adhesive layer.

[0069] adhesive layer

[0070] Specifically, the smart window may further include a first adhesive layer between the anti-fog layer and the variable transmittance layer, and a second adhesive layer between the variable transmittance layer and the second glass plate.

[0071] The first adhesive layer and the second adhesive layer may each independently include at least one selected from the group consisting of polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), and thermoplastic polyurethane (TPU).

[0072] In addition, the first adhesive layer and the second adhesive layer may each independently have an average thickness of 0.2 to 1.0 μm or 0.3 to 0.8 μm. When the average thickness of the first adhesive layer and the second adhesive layer is less than the above range, bubbles may be generated during bonding due to a difference in level with the anti-fog layer or the second glass plate, or the film may be easily torn due to the low thickness during the bonding process, making handling difficult and thus increasing the process time, or the glass and the film may be penetrated due to vulnerability to external impact after bonding. In addition, when the average thickness of the first adhesive layer and the second adhesive layer exceeds the above range, an additional process may need to be introduced in the bonding process to lower the hardness of the film due to the hardness of the adhesive layer, or the weight of the manufactured smart window may increase due to the thickness of the adhesive layer, which may cause a problem of increasing the fuel efficiency of the vehicle.

[0073] Specifically, the first adhesive layer may have an average thickness of 0.5 to 1.0 μm or 0.7 to 0.8 μm, and the second adhesive layer may have an average thickness of 0.2 to 0.5 μm or 0.3 to 0.4 μm. When the average thicknesses of the first adhesive layer and the second adhesive layer are within the above ranges, each layer and the glass plate can be effectively bonded with the thinnest possible thickness, and the step difference caused by the thickness difference between each layer can be appropriately compensated for.

[0074] The smart window according to the present invention may have a visible light transmittance of 5 to 30% or 10 to 20% when current is applied. In addition, the smart window may have a visible light transmittance of more than 0% and less than 5% or more than 0% and less than 1% when current is not applied.

[0075] Additionally, the smart window may have a heat transmittance of 2 to 15%, 5 to 10%, or 5 to 8% when current is applied.

[0076] Furthermore, the smart window may have a visible light reflectance of 1 to 10%, 1 to 5%, or 2 to 3% when no current is applied.

[0077] The above smart window may have a total energy transmittance of 5 to 20%, 10 to 15%, or 10 to 12% when no current is applied, calculated according to the KS L 2514 standard.

[0078] As described above, the smart window according to the present invention exhibits excellent durability, preventing problems such as reduced transmittance controllability even when exposed to harsh environments for extended periods. Furthermore, it boasts an appropriate visible light transmittance, ensuring an external view, and easily adjusts light transmittance. Therefore, the smart window is highly suitable as a construction material for residential and non-residential buildings, as well as for vehicles, and in various other fields.

[0079] In addition, when the smart window according to the present invention as described above is applied to a building or a vehicle, the first glass plate can be applied so that it is exposed to the outside and the anti-reflection layer is placed on the inside of the building or vehicle.

[0080] Hereinafter, the present invention will be described in more detail through experimental examples. However, these experimental examples are intended only to aid understanding of the present invention and are not intended to limit the scope of the present invention in any way.

[0081] [Experimental Example]

[0082] Experimental examples 1 to 13.

[0083] The thickness of each layer was controlled and laminated as described in Table 1. Specifically, each layer was manufactured by vacuum sputtering.

[0084] First, a 2.1 mm thick transparent glass substrate (first glass plate) was placed in a vacuum chamber and evacuated to form a vacuum, and then a dielectric layer was coated using a Si Rotary target under a nitrogen and argon atmosphere. Subsequently, a metal layer was coated on the dielectric layer using a Ag Planar target under an argon atmosphere. Subsequently, a metal protective layer was coated on the metal layer using a NiCr (Ni:Cr = 80:20 weight ratio) Planar target under a nitrogen and argon atmosphere. Subsequently, an anti-fog layer was coated on the metal protective layer using a ZnSnAlO Planar target, which is a Sn-Al-Zn oxide, under an argon atmosphere. Subsequently, an SPD variable film was adhered and laminated as a transmittance variable layer on the anti-fog layer. Subsequently, a 2.1 mm thick transparent glass substrate as a second glass plate was laminated on the transmittance variable layer, and an anti-reflection layer was coated on the second glass plate using an ITO (Indium Tin Oxide) Planar target in an argon atmosphere, thereby manufacturing a laminate.

[0085] (Thickness, nm) Dielectric layer Infrared reflective coating layer Anti-fog layer Transmittance variable layer Anti-reflection layer Metal layer Metal protective layer Experimental example 1258.51.07150360 Experimental example 21710.52.05190250 Experimental example 33814.54.58110300 Experimental example 458.51.07150360 Experimental example 5988.51.07150360 Experimental example 6250.50.57150360 Experimental example 7258.539.57150360 Experimental example 8258.51.0-150360 Experimental example 9258.51.019150360 Experimental example 10258.51.07150100 Experimental example 11258.51.07150500Experimental Example 1225-1.07150360Experimental Example 13258.5-7150360

[0086] Test example: Evaluation of laminate properties

[0087] The transmittance, reflectance, and total energy transmittance of the laminate manufactured in the experimental example were measured using the following methods, and the results are shown in Table 2.

[0088] Specifically, the laminate manufactured in the experimental example was heat-treated at 650°C for 7 minutes and rapidly cooled, and then its physical properties were evaluated.

[0089] The visible light and heat ray transmittance on the surface of the laminate, the reflectance of visible light on the four sides of the laminate and the heat ray on one side, and the total energy transmittance were measured in accordance with the KS L 2514 standard using a Lambda1050+ UV-VIS-NIR Spectrophotometer from PerkinElmer in the wavelength range of 280 to 2,500 nm (measured at 1 nm intervals below 800 nm and 5 nm intervals from 800 to 2,500 nm). At this time, the four sides of the laminate are the sides on which the antireflection layer is laminated, and the one side is the side on which the first glass plate is laminated. In addition, in Table 2, on means when current is applied, and off means when current is not applied.

[0090] Transmittance (%) Reflectance (%) Total energy transmittance (Tts) Visible light heating wire 4 sides Visible light 1 side heating wire target OFF ≤ 1.0- ≤ 3.0 ≥ 40.0 ≤ 12.0 ON ≥ 10.0 ≤ 8.0 ≤ 3.0--Experimental example 1 OFF 0.2 0.32 25 4 11.5 ON 17.9 7.8 2.6 5 4.2 18.2 Experimental example 2 OFF 0.2 0.32 5 7 11.2 ON 16.7 7.32 8 5 7.5 18.1 Experimental example 3 OFF 0.1 0.32 35 5.3 10.8 ON 16.2 7.12 6 5 5.6 17.9 Experimental example 4 OFF-----ON-----Experimental example 5OFF0.30.31.552.99.4ON8.56.8253.114.8Experimental example 6OFF0.20.31.853.312.9ON18.88.32.153.518.8Experimental example 7OFF0.20.35.85410.1ON9.17.86.154.214.9Experimental example 8OFF0.30.31.553.312ON9.45.31.753.417.5Experimental example 9OFF0.20.31.453.412.2ON9.55.51.953.917.9Experimental example 10OFF-----ON-----Experimental example 11OFF0.20.35.153.39.5ON117.95.954.515.1Experimental example 12OFF0.514.715.458.532.9ON50.825.717.360.435.6Experimental example 13OFF0.20.55.954.211.6ON12.19.56.055.118.1

[0091] As shown in Table 2, the laminates of Experimental Examples 1 to 3 all satisfied the target properties of visible light and heat ray transmittance, visible light and heat ray reflectance, and total energy transmittance, and thus were found to be very suitable as materials for various fields such as building materials for residential and non-residential buildings, and vehicles as smart windows.

[0092] On the other hand, in Experimental Example 4 with a thin dielectric layer and Experimental Example 10 with a thin antireflection layer, each layer coated on the glass plate was damaged, making it impossible to measure the physical properties.

[0093] In addition, Experimental Example 5 with a thick dielectric layer, Experimental Example 7 with a thick infrared reflective coating layer, Experimental Example 8 without an anti-fog layer, and Experimental Example 9 with a thick anti-fog layer had insufficient visible light transmittance when current was applied. In particular, Experimental Example 7 had a high visible light reflectance when current was applied and when current was not applied, which lowered visible light transmittance and caused a problem in which the outside could not be seen from inside the vehicle, and Experimental Example 9 had a high total energy transmittance when current was not applied, which caused a problem in which the interior temperature rose when applied to a vehicle.

[0094] Furthermore, Experimental Example 6 with a thin infrared reflective coating layer, Experimental Example 12 without a metal layer, and Experimental Example 13 without a metal protective layer had a problem in that the heat ray transmittance was high when current was applied, allowing a lot of heat energy to be transmitted, thereby increasing the temperature inside the vehicle when applied to the vehicle. In particular, Experimental Examples 6 and 12 had a problem in that the total energy transmittance was high when no current was applied, increasing the temperature inside the vehicle, and Experimental Examples 12 and 13 had a problem in that the visible light reflectance was high when current was applied and when no current was applied, thereby decreasing the visible light transmittance, making it impossible to see the outside from inside the vehicle.

[0095] In addition, Experimental Example 11, which had a thick anti-reflection layer, had a problem in that the visible light reflectance was high when current was applied and when it was not, and the visible light transmittance was low, making it impossible to see the outside from inside the vehicle.

Claims

1. First glass plate; A dielectric layer formed on the first glass plate; An infrared reflective coating layer formed on the dielectric layer and including a metal layer and a metal protective layer; An anti-fog layer formed on the infrared reflective coating layer and containing a metal oxide; A transmittance variable layer formed on the above anti-fog layer and containing an organic material; A second glass plate formed on the above-mentioned transmittance variable layer; and A smart window comprising an anti-reflection layer formed on the second glass plate and containing an inorganic material.

2. In claim 1, The above metal layer includes at least one selected from the group consisting of silver (Ag), gold (Au), and copper (Cu), A smart window, wherein the metal protective layer comprises at least one selected from the group consisting of nickel (Ni) and chromium (Cr), or a nitride or oxide thereof.

3. In claim 1, The above anti-fog layer contains zinc (Zn) oxide, A smart window, wherein the dielectric layer comprises a silicon-containing nitride or a silicon-containing nitride.

4. In claim 1, A smart window, wherein the anti-reflection layer comprises at least one inorganic material selected from the group consisting of indium tin oxide (ITO), antimony zinc oxide (AZO), antimony tin oxide (ATO), and tin oxide.

5. In claim 1, The above dielectric layer has an average thickness of 10 to 60 nm, The above infrared reflective coating layer has an average thickness of 5.1 to 40.0 nm, The above anti-fog layer has an average thickness of 1 to 10 nm, A smart window, wherein the anti-reflection coating layer has an average thickness of 150 to 450 nm.

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