JP7380572B2 - glass, laminated glass - Google Patents

Description

The present invention relates to glass and laminated glass.

Vehicles have a see-through area on the glass for safety, so that, for example, a passenger can grasp the situation outside the vehicle. Furthermore, in recent years, with the aim of improving vehicle safety, vehicles have been developed that have a function of automatically avoiding collisions with vehicles or pedestrians traveling ahead. Such a vehicle is equipped with a device such as a camera inside the vehicle, and transmits and receives information such as road conditions through the glass of the vehicle (for example, a windshield).

However, in the see-through area, it may be difficult to obtain information from outside the vehicle due to backlight from sunlight or the headlights of an oncoming vehicle. Similarly, devices such as cameras may have difficulty acquiring information from outside the vehicle due to backlight from sunlight, headlights of oncoming vehicles, and the like. Therefore, a technique has been proposed in which a liquid crystal panel is arranged in front of a device such as a camera, which is divided into a plurality of regions and can change the light transmittance for each region, that is, can control the light. This technology achieves anti-glare performance by averaging the difference in the amount of incident light that occurs between areas due to backlighting, etc., and leveling out the brightness of the entire image of a device such as a camera (for example, , see Patent Document 1).

Japanese Patent Application Publication No. 9-214827

However, when applying a light control element to vehicle glass, on-demand anti-glare performance cannot be achieved at low temperatures because the response speed of the light control element decreases at low temperatures (for example, around -20°C). .

The present invention has been made in view of the above points, and an object of the present invention is to improve the response speed of a light control element at low temperatures in a glass having a light control element.

The present glass is a glass for a vehicle, and includes a glass plate, a see-through area defined in the glass, and an area of the glass plate that is arranged in at least a part of an area that overlaps with the see-through area in a plan view. , a light control element capable of switching light transmittance, the light control element comprising a light control layer, a pair of conductive thin films sandwiching the light control layer, and a current flowing through the pair of conductive thin films. and a pair of heating bus bars that heat at least one of the pair of conductive thin films; The conductive thin film disposed in has a heat ray reflecting function, and the energy reflectance of the transparent area is required to be 25% or more .

According to one embodiment of the disclosure, in a glass having a light control element, the response speed of the light control element at low temperatures can be improved.

1 is a diagram illustrating a vehicle windshield according to a first embodiment; FIG. FIG. 2 is a diagram illustrating a light control element according to a first embodiment. FIG. 7 is a plan view illustrating a light control element according to Modification 1 of the first embodiment. FIG. 7 is a cross-sectional view illustrating a light control element according to a second modification of the first embodiment. It is a figure showing the cross-sectional structure of the laminated glass concerning a comparative example. It is a figure showing the conditions and results of an example and a comparative example.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same components are given the same reference numerals, and redundant explanations may be omitted. Further, in each drawing, the size and shape may be partially exaggerated to make it easier to understand the content of the present invention.

Note that although a vehicle windshield will be described here as an example, the present invention is not limited to this, and the glass according to the embodiment can be applied to other than vehicle windshields. In addition, here, the information transmission/reception area will be explained as an example of the see-through area, but the see-through area is not limited to this, and the see-through area refers to an area where light passes through the glass and the situation outside the vehicle can be grasped. Furthermore, the term "vehicle" is typically an automobile, but it also refers to a moving object having glass, including a train, a ship, an airplane, etc.

In addition, planar view refers to a predetermined area of the windshield viewed from the normal direction of the predetermined area, and planar shape refers to the shape of the predetermined area of the windshield viewed from the normal direction of the predetermined area. . Furthermore, in this specification, up and down refers to the Z-axis direction of the drawing, and left and right refers to the Y-axis direction of the drawing.

Further, the visible light transmittance of the present invention is a value defined by JIS R3108:1998.

Moreover, the energy reflectance of the present invention is a value defined by JIS R3108:1998.

<First embodiment>
FIG. 1 is a diagram illustrating a vehicle windshield according to a first embodiment, and FIG. 1(a) is a diagram schematically showing how the windshield is viewed from inside the vehicle to outside the vehicle. (The windshield 20 is attached to the vehicle with the Z direction facing upward). FIG. 1(b) is a cross-sectional view of the windshield 20 shown in FIG. 1(a) cut in the XZ direction and viewed from the Y direction. Note that although the device 300 is illustrated together with the windshield 20 for convenience in FIG. 1(b), the device 300 is not a component of the windshield 20.

As shown in FIG. 1, the windshield 20 includes a glass plate 21 that is a glass plate on the inside of the vehicle, a glass plate 22 that is a glass plate on the outside of the vehicle, an interlayer film 23, a shielding layer 24, and a light control element 25. This is laminated glass for vehicles.

In the windshield 20, a glass plate 21 and a glass plate 22 are fixed to each other with an intermediate film 23 and a light control element 25 sandwiched therebetween. The intermediate film 23 may be formed from multiple layers of intermediate films. Details of the glass plate 21, the glass plate 22, and the intermediate film 23 will be described later.

The shielding layer 24 is provided on the periphery of the vehicle-inside surface 21a of the glass plate 21. The shielding layer 24 is an opaque layer, and can be formed, for example, by applying printing ink of a predetermined color to a glass surface and baking it. The shielding layer 24 is, for example, an opaque (eg, black) colored ceramic layer. Due to the presence of the opaque shielding layer 24 on the peripheral edge of the windshield 20, an adhesive member such as urethane that holds the peripheral edge of the windshield 20 to the vehicle body and a bracket that locks the device 300 can be attached to the windshield 20. Deterioration of adhesive members etc. due to ultraviolet rays can be suppressed.

In addition, although the shielding layer 24 is provided on the vehicle inner side surface 21a of the glass plate 21 in FIG. 1(b), it is not limited thereto. The shielding layer 24 may be provided, for example, on the vehicle-inside surface of the glass plate 22, or on both the vehicle-inside surface 21a of the glass plate 21 and the vehicle-inside surface of the glass plate 22.

A test area A defined by JIS standard R3212 is defined in the windshield 20. Further, a see-through area, here an information transmission/reception area 26, is defined in the windshield 20. The test area A is located inside the area surrounded by the shielding layer 24 in plan view, and the information transmitting/receiving area 26 is located within the opening provided in the shielding layer 24.

The information transmitting/receiving area 26 functions as an area where the device 300 transmits and/or receives information when the device 300 is placed at the upper peripheral area of the windshield 20 in the vehicle. The planar shape of the information transmitting/receiving area 26 is not particularly limited, but may be, for example, an isosceles trapezoid. The information transmission/reception area 26 may be located above the test area A because it does not obstruct the driver's view when the windshield 20 is attached to the vehicle and is advantageous for transmitting and/or receiving information. preferable.

Note that the device 300 is a device that transmits and/or receives information, and includes, for example, a camera that acquires visible light, infrared light, etc., a millimeter wave radar, an infrared laser, etc., and is typically a camera. . In addition to the device 300, other devices that transmit and/or receive information via the information transmitting/receiving area 26 may be arranged in the vehicle. Here, the term "signal" refers to electromagnetic waves including millimeter waves, visible light, infrared light, and other light, typically visible light.

The light control element 25 is an information transmitting/receiving area located between the glass plate 21 and the glass plate 22 in at least a part of the area outside the test area A and overlapping with the information transmitting/receiving area 26 in plan view. It is an element that can switch the transmittance of 26 lights. The light control element 25 may be arranged inside the test area A between the glass plate 21 and the glass plate 22 in a plan view, if necessary.

The planar shape of the light control element 25 is, for example, preferably a rectangle that is slightly larger than the planar shape of the information transmitting/receiving area 26, but it may also be a trapezoid, or a rectangle or trapezoid with any side curved. or may have other shapes. The planar shape of the light control element 25 may be smaller than the planar shape of the information transmitting/receiving area 26.

FIG. 2 is a diagram illustrating the light control element according to the first embodiment, and FIG. 2(a) is a plan view schematically showing the vicinity of the information transmission and reception area as viewed from inside the vehicle to outside the vehicle. , FIG. 2(b) is a cross-sectional view taken along line AA in FIG. 2(a). In addition, in FIG. 2(a), illustration of the glass plates 21 and 22, the intermediate film 23, and the shielding layer 24 is omitted. Further, in FIG. 2(a), the information transmission/reception area 26 is shown by a broken line for convenience.

The light control element 25 is enclosed in the intermediate film 23 and includes a base material 251, a conductive thin film 252, a light control layer 253, a conductive thin film 254, a base material 255, a heating bus bar 256, and a light control layer 253. bus bar 257.

As the base materials 251 and 255, for example, transparent resin or glass can be used. The thickness of the base materials 251 and 255 can be 5 μm or more and 500 μm or less, preferably 10 μm or more and 200 μm or less, and more preferably 50 μm or more and 150 μm or less.

The plastic films serving as the base materials 251 and 255 are, for example, polyester (e.g., polyethylene terephthalate, polyethylene naphthalate, etc.), polyamide, polyether, polysulfone, polyether sulfone, polycarbonate, polyarylate, polyetherimide, polyether ether. It can be formed from a homopolymer or copolymer of at least one monomer selected from the group consisting of ketones, polyimides, aramids, polybutylene terephthalate, polyvinyl butyral, and polyethyl vinyl acetate. Examples of the glass material for the base materials 251 and 255 include soda lime glass, inorganic glass such as aluminosilicate, and organic glass.

The conductive thin film 252 is formed on the surface of the base material 251 on the glass plate 21 side, and is in contact with the surface of the light control layer 253 on the glass plate 22 side. The conductive thin film 254 is formed on the surface of the base material 255 on the glass plate 22 side, and is in contact with the surface of the light control layer 253 on the glass plate 21 side. That is, the conductive thin films 252 and 254 are a pair of conductive thin films with the light control layer 253 sandwiched therebetween.

As the conductive thin films 252 and 254, for example, transparent conductive oxide (TCO) can be used. Examples of the TCO include, but are not limited to, tin-doped indium oxide (ITO), aluminum doped zinc oxide (AZO), and indium-doped cadmium oxide.

Transparent conductive polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) or poly(4,4-dioctylcyclopentadithiophene) can also be suitably used as the conductive thin films 252 and 254. Further, as the conductive thin films 252 and 254, a laminated film of a metal layer and a dielectric layer, silver nanowires, a metal mesh of silver or copper, etc. can also be suitably used.

The conductive thin films 252 and 254 can be formed using, for example, a physical vapor deposition (PVD) method such as a sputtering method, a vacuum evaporation method, or an ion plating method. The conductive thin films 252 and 254 may be formed using a chemical vapor deposition (CVD) method or a wet coating method.

By the way, when applying the light control element 25 to the windshield 20, it is necessary to prevent the light control element 25 from becoming hot and deteriorating due to heat rays from the sun. In order to realize this, for example, it is possible to use the light control element 25 together with a heat ray reflective glass or a heat ray reflective film. In this case, if heat ray reflective glass is applied only in the vicinity of the information transmitting/receiving area 26, the cost will be high, so it is preferable to use a heat ray reflective film which is relatively low cost. However, when a heat ray reflective film is used, the transmittance of the windshield 20 decreases or the color of the windshield 20 changes due to the addition of the heat ray reflective film, which may impede the sensing performance of the device 300. There is.

In the windshield 20, instead of providing a heat ray reflection layer separately from the light control element 25, the conductive thin film 252 and/or the conductive thin film 254 for supplying electricity to the light control layer 253 has the function of a heat ray reflection layer. be able to. In this case, compared to the case where a heat ray reflective layer is provided separately from the light control element 25, the influence on the sensing performance of the device 300 can be reduced. That is, it is possible to suppress changes in the light control element 25 due to heat rays while maintaining the sensing performance of the device 300. Specifically, compared to the case where a heat ray reflective layer is provided separately from the light control element 25, the visible light transmittance in the light transmission mode of the portion of the windshield 20 where the light control element 25 is enclosed decreases and the color changes. can be suppressed.

Here, the color change is defined by the difference between the maximum and minimum values of transmittance at predetermined wavelengths (436nm, 546nm, 700nm), and the maximum and minimum values of transmittance at predetermined wavelengths (436nm, 546nm, 700nm). A difference of 12% or less was considered to be within an acceptable range. The predetermined wavelengths (436 nm, 546 nm, 700 nm) are wavelengths corresponding to blue, green, and red in the RGB color system defined by CIE (Commission Internationale de Illumination), and if the difference in transmittance between the three wavelengths is greater than 12%, This adversely affects the sensing performance of the device 300.

Note that in order to prevent the light control element 25 from becoming high temperature due to heat rays and deteriorating, the conductive thin film 252 and/or the conductive thin film 254 can have a function of a heat ray reflective layer. It is preferable that the conductive thin film 252 arranged has a heat ray reflecting function. Thereby, it is possible to effectively prevent the light control element 25 from becoming hot due to the heat rays, and it is possible to prevent the light control element 25 from deteriorating. Further, it is preferable that the energy reflectance of the information transmitting/receiving area 26 is 25% or more. Thereby, it is possible to effectively prevent the light control element 25 from becoming hot due to the heat rays, and it is possible to prevent the light control element 25 from deteriorating.

When the conductive thin film 252 and/or the conductive thin film 254 is provided with the function of a heat ray reflective layer, any of the materials listed above can be used as the material of the conductive thin film 252 and/or the conductive thin film 254. .

However, as the conductive thin film 252 and/or the conductive thin film 254, an n-layer (n is an integer of 2 or more) functional layer containing a material that reflects infrared rays and an n+1 dielectric layer laminated with the functional layer sandwiched therebetween. It is preferable to use a laminated film having a body layer. By using such a laminated film as the conductive thin film 252 and/or the conductive thin film 254, it becomes possible to increase the energy reflectance of the information transmission/reception area 26 (for example, 25% or more), and the The effect of suppressing deterioration can be improved.

For example, a laminated film that uses silver as a material that reflects infrared rays and has two functional layers containing silver and three dielectric layers laminated with the functional layer sandwiched therebetween, or a multilayer film that has three functional layers containing silver. It is possible to use a laminated film having a dielectric layer and four dielectric layers laminated with a functional layer sandwiched therebetween.

When the material that reflects infrared rays is silver, the functional layer containing silver may be formed only from silver, or may be a metal layer or alloy layer containing silver as a main component. When silver is the main component, metal elements other than silver may include, for example, Pd, Au, Cu, Pt, etc. The thicknesses of the functional layers and dielectric layers can be determined as appropriate depending on the total number of layers and the constituent materials of each layer, and can be, for example, about several nanometers to several hundred nanometers.

The light control layer 253 is sandwiched between the conductive thin film 252 and the conductive thin film 254. As the light control layer 253, for example, a suspended particle device (SPD) film can be used. As an SPD film, a general SPD film is constructed by sandwiching a polymer layer containing suspended particles that can be oriented by applying a voltage between two electrically insulating films coated with a transparent conductive film on the inside. Film is available. This kind of SPD film has a high visible light transmittance and high transparency due to the orientation of suspended particles in the polymer layer by turning on the power switch and applying a voltage between the transparent conductive films. become. When the power switch is off, suspended particles in the polymer layer are not oriented, resulting in low visible light transmittance and low transparency.

Note that as the light control layer 253, polymer dispersed liquid crystal (PDLC) may be used instead of the SPD film. PDLC films can be made by mixing prepolymers, nematic liquid crystals, and spacer materials in specific ratios and then placed between two flexible transparent conductive films. The principles of operation include: When no electric field is applied, the liquid crystal droplets can be randomly distributed in the polymeric material with their directors freely oriented. In such cases, the refractive index of the liquid crystal for normal light does not match that of the polymer material, causing a relatively strong scattering effect on the light, resulting in the PDLC film having a translucent or opaque "milky" appearance. Become. Under an electric field, a liquid crystal droplet can align its director along the direction of the external electric field due to its positive dielectric anisotropic property. If the refractive index of the liquid crystal for normal light matches that of the polymeric material, light will be able to pass through the PDLC film and therefore the PDLC film will have a transparent appearance. Specifically, the higher the voltage supplied to the PDLC film, the more transparent the PDLC film becomes.

Further, as the light control layer 253, polymer network liquid crystal (PNLC), guest host liquid crystal, TN type liquid crystal, VA type liquid crystal, photochromic, electrochromic, electrokinetic, etc. may be used.

Further, it is more desirable to use a light control layer 253 in which the oriented particles stand perpendicularly to the transparent conductive film when no voltage is applied. Such a light control layer can transmit light when no electric field is applied, and when a voltage is applied, the oriented particles lie down and can absorb or scatter light. This dimming mode is called a reverse mode, and can be realized using a liquid crystal material with negative dielectric anisotropy.

When the light control element 25 is disposed in the transparent area of the window glass of the vehicle, it is more desirable to use a reverse mode light control element 25 in view of the risk of disconnection failure due to the impact of an accident.

The pair of heating bus bars 256 extend in the Z direction along both ends of the surface of the conductive thin film 252 on the glass plate 21 side in the Y direction, and are disposed to face each other with the light control layer 253 in between. A pair of heating bus bars 256 are electrically connected to the conductive thin film 252 and heat the conductive thin film 252.

One pole of the pair of heating bus bars 256 is, for example, a positive pole, and is connected to the positive side of a power source such as a battery mounted on the vehicle via a lead wire or the like. Further, the other pole of the pair of heating bus bars 256 is, for example, a negative pole, and is connected to the negative side of a power source such as a battery mounted on the vehicle via a lead wire or the like.

When a current is supplied from a power source such as a battery to the conductive thin film 252 via the pair of heating bus bars 256, the conductive thin film 252 generates heat. Since the heat generated in the conductive thin film 252 warms the light control layer 253, it is possible to prevent the response speed of the light control element 25 from decreasing at low temperatures (for example, the temperature outside the vehicle is about -20°C), and even at low temperatures. On-demand anti-glare performance can be achieved.

Furthermore, the heat generated by the conductive thin film 252 warms the information transmitting/receiving area 26 of the windshield 20, removes freezing and fogging from the surfaces of the glass plates 21 and 22 that constitute the information transmitting/receiving area 26, and facilitates good sensing by the device 300. can be secured.

The amount of heat generated by the conductive thin film 252 heated by the heating bus bar 256 is preferably 600 W/m ² or more. More preferably, it is 800 W/m ² or more, more preferably 1000 W/m ² or more. Thereby, it is possible to effectively prevent a decrease in the response speed of the light control element 25 at low temperatures. Furthermore, the performance of removing frost and fog from the surfaces of the glass plates 21 and 22 constituting the information transmitting/receiving area 26 is improved, and even better sensing by the device 300 can be ensured.

Further, heating of the conductive thin film 252 can be effectively controlled by sensing the outside temperature. For example, if the outside temperature is higher than 5°C, the response speed of the light control element 25 will not decrease much, so the conductive thin film 252 will not be heated, but if the outside temperature is below 5°C, it will be heated, and the response speed of the light control element 25 will not decrease. Control can be performed to prevent a decrease in response speed. This not only suppresses unnecessary power consumption when the outside temperature is high, but also prevents the intermediate film 23 and the light control element 25 from becoming excessively high temperature and deteriorating due to the heat generated by the conductive thin film 252 when the outside temperature is high. It can also be prevented.

Note that the pair of heating bus bars 256 may be electrically connected to the conductive thin film 254 instead of the conductive thin film 252. In this case, the conductive thin film 254 can be heated. Alternatively, a pair of heating bus bars 256 may be electrically connected to the conductive thin film 252, and another pair of heating bus bars may be electrically connected to the conductive thin film 254. In this case, since the conductive thin films 252 and 254 can be heated, the overall amount of heat generated can be increased.

Although not shown in the cross section of FIG. 2B, the pair of dimming bus bars 257 extend in the Y direction along one end of the surface of the conductive thin film 252 on the glass plate 21 side in the Z direction. One of the pair of dimming bus bars 257 is electrically connected to the conductive thin film 252, and the other is electrically connected to the conductive thin film 254. to drive. The pair of dimming bus bars 257 is independent of the pair of heating bus bars 256.

One pole of the pair of dimming bus bars 257 is, for example, a positive pole, and is connected to the positive side of a power source such as a battery mounted on the vehicle via a lead wire or the like. Further, the other pole of the pair of dimming bus bars 257 is, for example, a negative pole, and is connected to the negative side of a power source such as a battery mounted on the vehicle via a lead wire or the like.

When voltage is supplied to the light control layer 253 from a power source such as a battery via the pair of light control bus bars 257, the transmittance of the light control layer 253 is switched according to the voltage.

Silver paste is preferably used as the heating bus bar 256 and the dimming bus bar 257. The silver paste can be applied, for example, by a printing method such as screen printing. The heating bus bar 256 and the dimming bus bar 257 are made of at least one metal selected from the group consisting of silver, copper, tin, gold, aluminum, iron, tungsten, and chromium, or two or more metals selected from this group. It may be formed from an alloy containing , or a conductive organic polymer by sputtering or the like. Further, as the heating bus bar 256 and the dimming bus bar 257, a copper ribbon, a plain knitted copper wire, or a copper tape having a conductive adhesive may be used.

The light control element 25 has a light transmission mode (a mode with high visible light transmittance) and a light absorption mode (a mode with low visible light transmittance). The maximum visible light transmittance of the information transmitting/receiving area 26 including the light control element 25 in the light transmission mode is within the permissible range if it is 40% or more, but it is preferably 50% or more. By setting the maximum visible light transmittance of the information transmitting/receiving region 26 including the light control element 25 in the light transmission mode to 50% or more, good sensing by the device 300 can be sufficiently ensured. Note that the maximum visible light transmittance refers to the visible light transmittance in a state where the voltage applied to the light control layer 253 is adjusted so that the visible light transmittance is maximized.

For example, when the light control element 25 is in a light transmission mode when energized, it is preferable that the maximum visible light transmittance can be 50% or more when energized. In this case, it is more preferable that the maximum visible light transmittance can be made 60% or more, and even more preferably 70% or more when electricity is applied. Further, when the light control element 25 is in the light absorption mode when not energized, it is preferable that the visible light transmittance can be made less than 20% when not energized. Further, it is desirable that the visible light transmittance is 5% or more. This is because if it is less than 5%, it will be difficult to recognize the situation outside the vehicle.

The light control element 25 may be in a light transmission mode when not energized. In this case, the energization/de-energization control may be reversed. In this case as well, it is preferable that the maximum visible light transmittance of the information transmitting and receiving area 26 including the light control element 25 in the light transmission mode can be made 50% or more, more preferably 60% or more, and even more preferably 70% or more. Preferably, the minimum visible light transmittance in light absorption mode is 5% or more.

By having the light control element 25, the windshield 20 can adjust the amount of light that passes through the information transmitting and receiving area 26 according to the amount of light that enters the information transmitting and receiving area 26 from outside the vehicle. For example, if the amount of incident light is excessive due to direct sunlight or the headlights of an oncoming vehicle, the amount of light transmitted through the information transmitting and receiving area 26 is reduced by lowering the visible light transmittance. The amount of light incident on can be adjusted to an appropriate amount. In addition, if the amount of light incident on the information transmission area is not excessive, the visible light transmittance of the low transmission area is changed to a high value so that sufficient light can be transmitted through the information transmission/reception area 26, and the light is transmitted to the device. The amount of light can be adjusted to an appropriate level.

Preferably, the windshield 20 further includes a control device that measures the amount of light that enters the information transmitting/receiving area 26 from outside the vehicle and controls energization and de-energization of the dimming element 25 according to this amount of light. For example, when a light control element with high visible light transmittance when energized is used as the light control element 25, such a control device can be used to maintain the power on state when the amount of incident light is not excessive. However, if the amount of incident light is excessive due to backlighting, etc., the power can be turned off. Thereby, the amount of light transmitted through the information transmitting/receiving area 26 can be optimized at all times, and the amount of light incident on the device 300 can be made appropriate. When using a light control element 25 that has a high visible light transmittance when not energized, a similar effect can be expected by reversing the energization/de-energization control.

Here, the glass plate 21, the glass plate 22, and the intermediate film 23 will be explained in detail.

In the windshield 20, a surface 21a of the glass plate 21 on the inside of the vehicle (inner surface of the windshield 20) and a surface 22a of the glass plate 22 on the outside of the vehicle (the outer surface of the windshield 20) may be flat or curved. It doesn't matter if there is.

As the glass plates 21 and 22, for example, soda lime glass, inorganic glass such as aluminosilicate, organic glass, etc. can be used. When the glass plates 21 and 22 are made of inorganic glass, they can be manufactured by, for example, a float method.

The thickness of the glass plate 22 located on the outside of the windshield 20 is preferably 1.8 mm or more and 3 mm or less at the thinnest part. When the thickness of the glass plate 22 is 1.8 mm or more, the strength such as stone flying resistance is sufficient, and when it is 3 mm or less, the mass of the laminated glass does not become too large, which is preferable in terms of fuel efficiency of the vehicle. The thickness of the glass plate 22 at its thinnest portion is more preferably 1.8 mm or more and 2.8 mm or less, and even more preferably 1.8 mm or more and 2.6 mm or less.

The thickness of the glass plate 21 located inside the windshield 20 is preferably 0.3 mm or more and 2.3 mm or less. When the thickness of the glass plate 21 is 0.3 mm or more, handling properties are good, and when the thickness is 2.3 mm or less, the mass of the windshield 20 does not become too large. Note that the glass plate 21 and the glass plate 22 may have a wedge-shaped cross section.

However, the thickness of the glass plates 21 and 22 is not always constant and may vary from place to place as necessary. For example, one or both of the glass plates 21 and 22 may include a wedge-shaped region in cross section where the upper end side in the vertical direction is thicker than the lower end side when the windshield 20 is attached to a vehicle.

When the windshield 20 has a curved shape, the glass plates 21 and 22 are bent and formed after being formed by a float method or the like and before being bonded with the interlayer film 23. Bending is performed by softening the glass by heating. The heating temperature of the glass during bending is approximately 550°C to 700°C.

Thermoplastic resins are often used as the intermediate film 23 for bonding the glass plates 21 and 22 together, such as plasticized polyvinyl acetal resin, plasticized polyvinyl chloride resin, saturated polyester resin, and plasticized saturated polyester. Examples of thermoplastic resins conventionally used for this type of use include polyurethane resins, polyurethane resins, plasticized polyurethane resins, ethylene-vinyl acetate copolymer resins, and ethylene-ethyl acrylate copolymer resins. Further, a resin composition containing a hydrogenated modified block copolymer described in Japanese Patent No. 6065221 can also be suitably used.

Among these, plasticized polyvinyl acetal resin has an excellent balance of performance such as transparency, weather resistance, strength, adhesive strength, penetration resistance, impact energy absorption, moisture resistance, heat insulation, and sound insulation. is preferably used. These thermoplastic resins may be used alone or in combination of two or more. "Plasticized" in the above-mentioned plasticized polyvinyl acetal resin means plasticized by addition of a plasticizer. The same applies to other plasticized resins.

The above-mentioned polyvinyl acetal resins include polyvinyl formal resins obtained by reacting polyvinyl alcohol (hereinafter sometimes referred to as "PVA" as necessary) and formaldehyde, and polyvinyl formal resins obtained by reacting PVA and acetaldehyde. polyvinyl acetal resins, polyvinyl butyral resins obtained by reacting PVA and n-butyraldehyde (hereinafter sometimes referred to as "PVB" as needed), etc., which have particularly good transparency and weather resistance. PVB is preferred because it has an excellent balance of various properties such as strength, adhesive strength, penetration resistance, impact energy absorption, moisture resistance, heat insulation, and sound insulation. Note that these polyvinyl acetal resins may be used alone or in combination of two or more types. However, the material forming the intermediate film 23 is not limited to thermoplastic resin. Further, the intermediate film 23 may contain functional particles such as an infrared absorber, an ultraviolet absorber, and a luminescent agent.

The thickness of the intermediate film 23 is preferably 0.5 mm or more at the thinnest part. When the thickness of the intermediate film 23 is 0.5 mm or more, the penetration resistance necessary for a windshield will be sufficient. Further, the thickness of the intermediate film 23 is preferably 3 mm or less at the thickest portion. When the maximum thickness of the interlayer film 23 is 3 mm or less, the mass of the laminated glass does not become too large. The maximum value of the intermediate film 23 is more preferably 2.8 mm or less, and even more preferably 2.6 mm or less. Further, the intermediate film 23 may have a wedge-shaped cross section.

Note that the intermediate film 23 may have three or more layers. For example, the sound insulation properties of laminated glass can be improved by constructing the interlayer film from three layers and making the hardness of the middle layer lower than the hardness of the layers on both sides by adjusting the plasticizer or the like. In this case, the hardness of the layers on both sides may be the same or different.

In order to produce the intermediate film 23, for example, the above-mentioned resin material that will become the intermediate film is appropriately selected, and extrusion molded in a heated and molten state using an extruder. Extrusion conditions such as extrusion speed of the extruder are set to be uniform. Thereafter, the extruded resin film is stretched, for example, as necessary, in order to have curvature on the upper and lower sides in accordance with the design of the windshield 20, thereby completing the intermediate film 23.

To produce laminated glass, an interlayer film 23 and a light control element 25 are sandwiched between a glass plate 21 and a glass plate 22 to form a laminate. Then, for example, this laminate is placed in a rubber bag and bonded at a temperature of about 70 to 110° C. in a vacuum of -65 to -100 kPa. The heating conditions, temperature conditions, and lamination method are appropriately selected in consideration of the properties of the light control element, for example, so as not to deteriorate during lamination.

Furthermore, a laminated glass with even better durability can be obtained by performing a pressure bonding process by heating and pressing under conditions of, for example, 100 to 150° C. and a pressure of 0.6 to 1.3 MPa. However, in some cases, this heating and pressing step may not be used in order to simplify the process and take into account the characteristics of the material sealed in the laminated glass.

Between the glass plate 21 and the glass plate 22, in addition to the interlayer film 23 and the light control element 25, there is provided a material having functions such as light emission, visible light reflection, scattering, decoration, and absorption, within a range that does not impair the effects of the present invention. It may also include a film or a device. The above functional films and devices may be formed directly on the main surfaces of the glass plates 21 and 22.

In this way, the windshield 20 has the light control element 25. The light control element 25 includes a light control layer 253, conductive thin films 252 and 254 sandwiching the light control layer 253, and a light control bus bar 257 that drives the light control layer 253 by supplying current to the conductive thin films 252 and 254. and a heating bus bar 256 that heats the conductive thin film 252.

Thereby, the conductive thin film 252 can be heated via the heating bus bar 256, so even if the temperature outside the vehicle is low, the temperature of the light control layer 253 can be made higher than the temperature outside the vehicle. As a result, even when the temperature outside the vehicle becomes low, it is possible to prevent the response speed of the light control element 25 from decreasing, and on-demand anti-glare performance can be achieved.

Further, in the windshield 20, it is preferable that the conductive thin film 252 and/or the conductive thin film 254 have the function of a heat ray reflecting layer. This makes it possible to maintain the sensing performance of the device 300 without providing a heat ray reflective layer separately from the light control element 25, while reducing the possibility that the light control element 25 will become hot due to heat rays, and the light control element 25 will deteriorate. It is possible to prevent the risk of Additionally, in this case, compared to the case where a heat ray reflective layer is provided separately from the light control element 25, the visible light transmittance of the portion of the windshield 20 in which the light control element 25 is enclosed is lowered and the color changes in the light transmission mode. can be suppressed.

<Modification 1 of the first embodiment>
Modification 1 of the first embodiment shows an example in which one of the heating busbars also serves as a dimming busbar. Note that in Modification 1 of the first embodiment, descriptions of components that are the same as those of the already described embodiments may be omitted.

FIG. 3 is a plan view illustrating a light control element according to Modification 1 of the first embodiment, and schematically shows the vicinity of the information transmission/reception area viewed from inside the vehicle to outside the vehicle. Note that the cross-sectional structure of the light control element according to Modification 1 of the first embodiment is the same as that in FIG. 2(b), so illustration thereof is omitted.

As shown in FIG. 3, in the windshield 20A according to the first modification of the first embodiment, the light control element 25A only controls one light control bus bar 257 electrically connected to the conductive thin film 254. have. The other points of the light control element 25A are the same as the light control element 25.

Since the heating bus bar 256 is electrically connected to the conductive thin film 252, when a voltage is applied between either one of the heating bus bars 256 and the dimming bus bar 257, the dimming layer 253 changes depending on the voltage. Transmittance can be changed. That is, in the light control element 25A, one of the heating bus bars 256 also serves as the light control bus bar 257.

In this way, since one of the heating bus bars 256 also serves as the dimming bus bar 257, the structure of the dimming element 25A can be made simpler than the structure of the dimming element 25.

<Modification 2 of the first embodiment>
Modification 2 of the first embodiment shows an example in which the windshield is not a laminated glass. Although this embodiment is suitable as a side glass and a rear glass, it will be described herein as an embodiment as a windshield. Note that in the second modification of the first embodiment, descriptions of components that are the same as those in the already described embodiments may be omitted.

FIG. 4 is a sectional view illustrating a light control element according to a second modification of the first embodiment, and shows a cross section corresponding to FIG. 2(b). In the second modification of the first embodiment, the plan view schematically showing the vicinity of the information transmission/reception area as viewed from inside the vehicle interior to the outside of the vehicle interior is the same as that in FIG. Omitted.

As shown in FIG. 4, the windshield 20B is glass for a vehicle (not laminated glass), and includes a glass plate 22, a light control element 25, and an adhesive layer 27. The light control element 25 is fixed to the vehicle inner side surface 22b of the glass plate 22 by an adhesive layer 27.

The material of the adhesive layer 27 is not particularly limited as long as it has the function of fixing the light control element 25, but examples thereof include acrylic, acrylate, urethane, urethane acrylate, epoxy, epoxy acrylate, and polyolefin. , modified olefin-based, polypropylene-based, ethylene vinyl alcohol-based, vinyl chloride-based, chloroprene rubber-based, cyanoacrylate-based, polyamide-based, polyimide-based, polystyrene-based, and polyvinyl butyral-based materials. The material of the adhesive layer 27 is transparent to visible light. The thickness of the adhesive layer 27 can be, for example, 0.2 μm or more and 70 μm or less.

In this way, even when the windshield 20B is not laminated glass, the light control element 25 includes the heating bus bar 256 that heats the conductive thin film 252 in addition to the light control bus bar 257 that drives the light control layer 253. This produces the same effects as the first embodiment. Furthermore, by providing the conductive thin film 252 and/or the conductive thin film 254 with the function of a heat ray reflecting layer, the same effects as in the first embodiment can be achieved.

<Examples and comparative examples>
[Example 1]
In Example 1, a laminated glass provided with a light control element 25 shown in FIG. 2 was produced. Specifically, clear glass with a thickness of 2 mm was used as the glass plates 21 and 22, and the size was a flat plate of 150 mm x 150 mm. As the intermediate film 23, PVB with a thickness of 0.38 mm was used.

As the light control element 25, the SPD-A had the same structure as LCF-1103DHA (manufactured by Hitachi Chemical Co., Ltd., thickness 30 μm). Specifically, a base material 251 in which ITO is formed by sputtering as a conductive thin film 252, a base material 255 in which ITO is formed by sputtering as a conductive thin film 254, and conductive thin films 252 and 254 are formed on a light control layer 253. The light control element 25 was produced by arranging the two elements so as to sandwich them therebetween.

The amount of heat generated by the conductive thin film 252 connected to the heating bus bar 256 was set to 800 [W/m ² ]. Further, in this configuration, the energy reflectance of the portion of the laminated glass in which the light control element 25 is enclosed is 6%.

[Example 2]
In Example 2, Ag3 was used as the conductive thin film 252. Further, the calorific value of the conductive thin film 252 connected to the heating bus bar 256 was set to 1000 [W/m ² ]. Further, in this configuration, the energy reflectance of the portion of the laminated glass in which the light control element 25 is enclosed is 35%. Other than that, a laminated glass was produced in the same manner as in Example 1. In addition, Ag3 is made by alternately sputtering three functional layers containing silver and four dielectric layers of oxide containing zinc and tin as main components, which are laminated to sandwich the functional layer. It is a laminated film.

[Example 3]
In Example 3, Ag2 was used as the conductive thin film 252. Further, the calorific value of the conductive thin film 252 connected to the heating bus bar 256 was set to 600 [W/m ² ]. Further, in this configuration, the energy reflectance of the portion of the laminated glass in which the light control element 25 is enclosed is 25%. Other than that, a laminated glass was produced in the same manner as in Example 1. In addition, Ag2 is a method in which two functional layers containing silver and three dielectric layers of oxide containing zinc and tin as main components are alternately stacked with the functional layer sandwiched between them by sputtering. It is a laminated film.

[Example 4]
In Example 4, as the light control element 25, SPD-B had the same structure as LCF-1103DHA (manufactured by Hitachi Chemical Co., Ltd., thickness 90 μm). Specifically, a base material 251 in which ITO is formed by sputtering as a conductive thin film 252, a base material 255 in which ITO is formed by sputtering as a conductive thin film 254, and conductive thin films 252 and 254 are formed on a light control layer 253. The light control element 25 was produced by arranging the two elements so as to sandwich them therebetween. Other than that, a laminated glass was produced in the same manner as in Example 1.

[Comparative example 1]
In Comparative Example 1, no heating bus bar was provided. Other than that, a laminated glass was produced in the same manner as in Example 1.

[Comparative example 2]
In Comparative Example 2, as shown in FIG. 5, a laminated glass was used, in which a heat ray reflective film 35 in which Ag3 was formed as a heat ray reflective layer 352 on a base material 351 was sealed on the outer side of the vehicle than the light control element 25 of the intermediate film 23. Created. Further, in this configuration, the energy reflectance of the portion of the laminated glass in which the light control element 25 is enclosed is 35%. Other than that, a laminated glass was produced in the same manner as in Example 1.

[Comparative example 3]
In Comparative Example 3, the calorific value of the conductive thin film 252 connected to the heating bus bar 256 was set to 500 [W/m ² ]. Other than that, a laminated glass was produced in the same manner as in Example 1.

[evaluation]
First, the laminated glass was placed in a low temperature environment of -20° C., and the response speed of the light control element 25 at low temperatures was evaluated. Here, the response speed is defined as a change in transmittance of 50% when changing from light absorption mode to light transmission mode, assuming that the difference in transmittance between light transmission mode and light absorption mode in the light control element 25 is 100. This is the time it takes to If the response speed was less than 3 seconds, it was marked as ○, and if it was 3 seconds or more, it was marked as ×.

Second, suppression of deterioration of the light control element 25 was evaluated. Specifically, using a super xenon weather meter, ultraviolet rays were applied to the part of the laminated glass in which the dimming element 25 was enclosed under the conditions of an ultraviolet irradiance of 180 W/m ² (300 to 400 nm) and a black panel temperature (BPT) of 63°C. A test was conducted in which irradiation was performed for 3000 hours. After the test, measure the transmittance retention rate of the light control element 25 in the light transmission mode (ratio of transmittance in the light transmission mode before and after the test), and if the retention rate is 90% or more, ◎, 80% or more and 90%. If it is less than 80%, it is marked as ○, and if it is less than 80%, it is marked as ×.

Thirdly, evaluate the visible light transmittance (Tv) of the light control element 25 in the light transmission mode, and if the maximum visible light transmittance is 60% or more, ◎, and if the maximum visible light transmittance is 50% or more and less than 60%, ○. If it was 40% or more and less than 50%, it was rated Δ, and if it was less than 40%, it was rated ×.

Fourth, the change in color of the light control element 25 in the light transmission mode was evaluated. The color change is defined by the transmittance at the predetermined wavelengths (436nm, 546nm, 700nm), and if the difference between the maximum and minimum transmittance at the predetermined wavelengths (436nm, 546nm, 700nm) is 12% or less, it is ○, 12%. If it is larger, it is marked as ×.

The conditions and results of Examples and Comparative Examples are summarized in FIG. Note that in any evaluation, "x" indicates an unfavorable state. Also, "△", "〇", and "◎" all indicate favorable conditions, but "〇" is more preferable than "△", and "◎" is more preferable than "〇". preferable.

As shown in FIG. 6, regarding the response speed of the light control element 25 at low temperature (-20° C.), a heating bus bar 256 is provided on the conductive thin film 252, and the conductive thin film 252 has a heating value of 600 [W/m It can be seen that the reduction can be suppressed by heating to a temperature of ² ] or higher. Note that 600 [W/m ² ] is a sufficient amount of heat to clear fog from laminated glass and to unfreeze moisture adhering to window glass in winter.

On the other hand, in Comparative Example 1, since no heating bus bar is provided and the conductive thin film 252 cannot be heated, the response speed of the light control element 25 at low temperature (-20° C.) is reduced. In Comparative Example 3, although a heating bus bar is provided, the amount of heat generated by the conductive thin film 252 is less than 600 [W/m ² ], which is insufficient, so dimming at low temperatures (-20°C) is not possible. The response speed of element 25 has decreased.

Regarding suppression of deterioration of the light control element 25, the retention rate of the transmittance of the light control element 25 in the light transmission mode is 80% or more, which is within the permissible range. However, when Ag2 or Ag3 is used as the heat ray reflective layer (when the energy reflectance of the part of the laminated glass in which the light control element 25 is enclosed is 25% or more), the effect of suppressing the deterioration of the light control element 25 is Especially big.

The maximum visible light transmittance of the light control element 25 in the light transmission mode is all 40% or more, which is within the permissible range. In particular, when the conductive thin film 252 is made of Ag2, it has excellent performance in both preventing a decrease in response speed and suppressing deterioration of the light control element 25, and also achieves maximum visible light transmission in the light transmission mode of the light control element 25. In terms of ratio, we were able to secure a rate of 60% or more, and it can be said that this is a preferable configuration.

Regarding the color change in the light transmission mode of the light control element 25, Examples 1 to 4 and Comparative Examples 1 and 3 are within the permissible range. However, in Comparative Example 2, the difference between the maximum value and the minimum value of the transmittance at the predetermined wavelengths (436 nm, 546 nm, 700 nm) is larger than 12%, which adversely affects the sensing performance of the device 300. That is, in the configuration in which a heat ray reflective film is inserted separately from the light control element as in Comparative Example 2, although the decrease in response speed of the light control element 25 at low temperatures (-20° C.) can be improved, the sensing performance of the device 300 is There will be an adverse effect that will hinder the Therefore, the configuration shown in FIG. 5 is not preferable.

Although the preferred embodiments have been described in detail above, they are not limited to the embodiments described above, and various modifications may be made to the embodiments described above without departing from the scope of the claims. Variations and substitutions can be made.

This international application claims priority based on Japanese Patent Application No. 2018-168518 filed on September 10, 2018, and the entire contents of Japanese Patent Application No. 2018-168518 are incorporated into this international application. .

20, 20A, 20B Windshield 21 Glass plates 21a, 22a, 22b Surface 22 Glass plate 23 Intermediate film 24 Shielding layer 25, 25A Light control element 26 Information transmission/reception area 27 Adhesive layer 251, 255 Base material 252, 254 Conductive thin film 253 Light control layer 256 Heating bus bar 257 Light control bus bar

Claims (16)

Glass for vehicles,
glass plate and
a see-through area defined in the glass;
a dimming element capable of switching light transmittance, disposed in at least a part of an area of the glass plate that overlaps with the see-through area in plan view;
The light control element is
a light control layer;
a pair of conductive thin films sandwiching the light control layer;
a light control bus bar that drives the light control layer by applying electricity to the pair of conductive thin films;
a pair of heating bus bars that heat at least one of the pair of conductive thin films ,
Among the pair of conductive thin films, at least the conductive thin film disposed on the outside of the vehicle has a heat ray reflecting function, and the glass has an energy reflectance of 25% or more in the transparent area. Glass for vehicles,
glass plate and
a see-through area defined in the glass;
a dimming element capable of switching light transmittance, disposed in at least a part of an area of the glass plate that overlaps with the see-through area in plan view;
The light control element is
a light control layer;
a pair of conductive thin films sandwiching the light control layer;
a light control bus bar that drives the light control layer by applying electricity to the pair of conductive thin films;
a pair of heating bus bars that heat at least one of the pair of conductive thin films ,
Of the pair of conductive thin films, at least the conductive thin film disposed on the outside of the vehicle is glass containing silver . Glass for vehicles,
glass plate and
a see-through area defined in the glass;
a dimming element capable of switching light transmittance, disposed in at least a part of an area of the glass plate that overlaps with the see-through area in plan view;
The light control element is
a light control layer;
a pair of conductive thin films sandwiching the light control layer;
a light control bus bar that drives the light control layer by applying electricity to the pair of conductive thin films;
a pair of heating bus bars that heat at least one of the pair of conductive thin films ,
Of the pair of conductive thin films, the conductive thin film disposed at least on the outside of the vehicle includes an n-layer (n is an integer of 2 or more) functional layer containing a material that reflects infrared rays, and a functional layer sandwiching the functional layer. A glass having n+1 dielectric layers laminated . Glass for vehicles,
glass plate and
a see-through area defined in the glass;
a dimming element capable of switching light transmittance, disposed in at least a part of an area of the glass plate that overlaps with the see-through area in plan view;
The light control element is
a light control layer;
a pair of conductive thin films sandwiching the light control layer;
a light control bus bar that drives the light control layer by applying electricity to the pair of conductive thin films;
a pair of heating bus bars that heat at least one of the pair of conductive thin films ,
The light control element is glass that is any one of a TN type liquid crystal, a VA type liquid crystal, a guest host type liquid crystal, a polymer dispersed liquid crystal, a polymer network type liquid crystal, and a suspended particle device. The glass according to claim 1 , wherein at least one of the pair of conductive thin films disposed on the outside of the vehicle contains silver. Of the pair of conductive thin films, the conductive thin film disposed at least on the outside of the vehicle includes an n-layer (n is an integer of 2 or more) functional layer containing a material that reflects infrared rays, and a functional layer sandwiching the functional layer. 6. The glass according to claim 1 , comprising n+1 dielectric layers laminated. 5. The light control element is any one of a TN type liquid crystal, a VA type liquid crystal, a guest host type liquid crystal, a polymer dispersed type liquid crystal, a polymer network type liquid crystal, and a suspended particle device . Or the glass described in 6 . The glass according to any one of claims 1 to 7 , wherein the transparent area is an information transmission/reception area in which a device mounted in a vehicle transmits and/or receives information. The light control element has a light transmission mode and a light absorption mode,
The glass according to any one of claims 1 to 8, wherein the maximum visible light transmittance of the transparent region including the light control element in the light transmission mode is 50% or more. The glass according to claim 9 , wherein the light control element is in the light transmission mode when not energized. The glass according to any one of claims 1 to 10 , wherein the pair of heating bus bars are arranged to face each other. The dimming bus bar includes a pair of dimming bus bars,
The glass according to any one of claims 1 to 11 , wherein the pair of dimming bus bars and the pair of heating bus bars are independent. The glass according to any one of claims 1 to 11 , wherein one of the pair of heating bus bars also serves as the dimming bus bar. The glass according to any one of claims 1 to 13 , wherein the amount of heat generated by the conductive thin film heated by the pair of heating bus bars is 600 W/ ^m2 or more. The glass according to any one of claims 1 to 14, wherein the dimming bus bar extends in a direction perpendicular to an extending direction of the pair of heating bus bars when viewed in plan. The glass according to any one of claims 1 to 15 , an interlayer film, and a second glass plate, wherein the glass plate and the second glass plate are bonded with the interlayer film interposed therebetween. A laminated glass for vehicles,
A laminated glass in which the light control element is encapsulated in the intermediate film.

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