Laminated Glass

Abstract

To suppress reflected double images in laminated glass with a non-constant wedge angle, even if the HUD display area is larger than before. [Solution] The laminated glass comprises a first glass sheet that faces the inside of a vehicle, a second glass sheet that faces the outside of the vehicle, and an interlayer film that is located between the first glass sheet and the second glass sheet and bonds the first glass sheet to the second glass sheet, and the laminated glass has a display area for use in a head-up display, and the display area has a wedge-shaped cross-section that is thicker at the top end in the vertical direction than at the bottom end when the laminated glass is installed in the vehicle, and in at least a part of the wedge-shaped area, the value of the wedge angle varies depending on the position in the vertical direction, and the vertical viewing angle of the display area is 2 degrees or more, and the maximum deviation of the measured value of the wedge angle from a linear approximation line obtained by approximating the measured value of the wedge angle at each position in the vertical direction of the display area with a linear function is 0.2 mrad or less.

Description

[Technical field]

[0001] The present invention relates to laminated glass. [Background technology]

[0002] In recent years, head-up displays (hereinafter referred to as HUDs), which reflect images onto the vehicle windshield to display specified information within the driver's field of vision, have been increasingly introduced. However, double images can sometimes be a problem when the driver is trying to view the scenery outside the vehicle or the information displayed by the HUD.

[0003] There are two types of double images that are problematic for vehicle drivers: see-through double images and reflective double images. If the windshield has a HUD display area used by the HUD and an area outside the HUD display (see-through area) that is not used by the HUD, see-through double images can be a problem in the HUD display area, but generally reflective double images are the main problem, and see-through double images are a problem in the area outside the HUD display.

[0004] It is known that such reflected double images or see-through double images can be reduced by using laminated glass with a wedge-shaped cross section as viewed from the horizontal direction for the windshield. For example, a laminated glass has been proposed in which an interlayer film with a wedge-shaped cross section is sandwiched between two glass sheets, and the wedge angle of the interlayer film varies depending on the location on the windshield (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2017-502125 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, in the past, the HUD display area was relatively narrow, so even if the deviation (error) of the wedge angle of the interlayer from the target value was large, the reflected double image was difficult to perceive.

[0007] However, if the HUD display area becomes larger than before in order to display more information (if an attempt is made to project a larger image onto the windshield than before), even a slight change in the shape of the windshield will have a significant effect on the projected image. In other words, if the wedge angle of the interlayer film deviates significantly from the target value, it will no longer be possible to suppress double images.

[0008] The present invention has been made in consideration of the above-mentioned points, and has an object to suppress reflected double images in laminated glass having a non-constant wedge angle, even when the HUD display area is larger than before. [Means for solving the problem]

[0009] The laminated glass includes a first glass sheet that is disposed inside a vehicle, a second glass sheet that is disposed outside the vehicle, and an interlayer film that is located between the first glass sheet and the second glass sheet and bonds the first glass sheet and the second glass sheet, the laminated glass including a display area for use in a head-up display, the display area including a region that has a wedge-shaped cross section and that is thicker at an upper end side than at a lower end side in a vertical direction when the laminated glass is attached to the vehicle, and a value of a wedge angle varies depending on a position in the vertical direction in at least a part of the wedge-shaped region, the display area has a viewing angle in the vertical direction of 2 deg or more, and a maximum deviation of a measured value of the wedge angle from a linear approximation line that approximates measured values ​​of the wedge angle at each position in the vertical direction of the display area with a linear function is 0.2 mrad or less, the linear approximation line is inclined in a direction in which the wedge angle becomes smaller from the lower end side to the upper end side in the vertical direction when the viewing angle in the vertical direction is less than 2.5 degrees, and is inclined in a direction in which the wedge angle becomes larger from the lower end side to the upper end side in the vertical direction when the viewing angle in the vertical direction is 2.5 degrees or more, and an absolute value of the inclination of the linear approximation line is 0.0006 mrad / mm or more and 0.006 mrad / mm or less, The wedge angle is equal to or smaller than 0.4 mrad over the entire display area. Effect of the Invention

[0010] According to the disclosed technology, in laminated glass having a non-constant wedge angle, it is possible to suppress reflected double images even when the HUD display area is larger than before. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating the concept of double images. [Diagram 2] FIG. 1 is a diagram illustrating a windshield for a vehicle. [Diagram 3] 3 is a partial cross-sectional view of the windshield 20 shown in FIG. 2 cut in the XZ direction and viewed from the Y direction. [Figure 4] 3 is a cross-sectional view of the windshield 20 shown in FIG. 2 cut in the XZ direction and viewed from the Y direction. [Diagram 5] 11 is a diagram illustrating an example of deviation amount of a wedge angle in a HUD display area. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same components are given the same reference numerals, and duplicated explanations may be omitted. Here, a vehicle windshield will be described as an example, but the present invention is not limited to this, and the laminated glass according to the present embodiment can be applied to applications other than vehicle windshields.

[0013] [Reflection double image, perspective double image] First, the concepts of reflected double images and perspective double images will be explained. Figure 1 is a diagram for explaining the concept of double images, with Figure 1(a) showing a reflected double image and Figure 1(b) showing a perspective double image. In Figure 1, the front-to-rear direction of the vehicle equipped with the windshield 20 is designated as X, the left-to-right direction of the vehicle is designated as Y, and the direction perpendicular to the XY plane is designated as Z (the same applies to the following figures).

[0014] As shown in FIG. 1(a), a portion of light ray 11a emitted from the HUD's light source 10 is reflected by the inner surface 21 of the vehicle's windshield 20 and guided to the driver's eye 30 as light ray 11b (primary beam), and is visually recognized by the driver as image 11c (virtual image) in front of the windshield 20.

[0015] Also, a part of the light ray 12a emitted from the light source 10 of the HUD enters the vehicle through the inner surface 21 of the windshield 20 and is refracted, and a part of it is reflected by the outer surface 22. Then, a further part of it exits the vehicle through the inner surface 21 to the outside of the windshield 20 and is refracted, and is guided to the driver's eye 30 as light ray 12b (secondary beam), and is visually recognized by the driver as image 12c (virtual image).

[0016] Thus, the two images 11c and 12c visually recognized by the driver are a reflected double image. The angle between the light ray 11b (primary beam) and the light ray 12b (secondary beam) is the angle α of the reflected double image. The closer the angle α of the reflected double image is to zero, the better. In this application, the reflected double image when the secondary beam is seen upward by the driver is defined as a positive value.

[0017] 1(b), a part of the light ray 41a emitted from the light source 40 enters the vehicle windshield 20 from the outer surface 22 and is refracted. Then, a part of the light ray 41a exits the windshield 20 from the inner surface 21, is refracted, and is guided to the driver's eye 30 as a light ray 41b, and is visually recognized by the driver as an image 41c.

[0018] Part of the light ray 42a emitted from the light source 40 penetrates the windshield 20 of the vehicle from the outer surface 22 and is refracted, and part of it is reflected by the inner surface 21. Then, part of it is reflected by the outer surface 22, and part of it exits the windshield 20 from the inner surface 21 and is refracted, being guided as light ray 42b to the driver's eye 30 and visually recognized by the driver as image 42c.

[0019] In this way, the two images 41c and 42c visually recognized by the driver are a perspective double image. The angle between the light ray 41b (primary beam) and the light ray 42b (secondary beam) is the angle η of the perspective double image. The closer the angle η of the perspective double image is to zero, the more preferable it is.

[0020] [Windshield (laminated glass)] Fig. 2 is a diagram illustrating a windshield for a vehicle, and is a diagram showing a schematic diagram of a state in which the windshield is viewed from inside the vehicle to the outside of the vehicle. For convenience, in Fig. 2, the HUD display area is shown with a satin pattern.

[0021] 2(a), the windshield 20 has a HUD display area A used by the HUD and a non-HUD display area B (see-through area) not used by the HUD. The HUD display area A is the range where light from the mirror constituting the HUD is irradiated onto the windshield 20 when the mirror constituting the HUD is rotated and viewed from point V1 of JIS R3212.

[0022] The HUD display area A is located below the windshield 20, and the HUD non-display area B is located adjacent to the HUD display area A and around the HUD display area A on the windshield 20. However, the HUD display area may be divided into a plurality of areas in the Y direction, such as the HUD display area A1 and the HUD display area A2 shown in FIG. 2(b). Alternatively, the HUD display area may be only one of the HUD display area A1 and the HUD display area A2. Alternatively, the HUD display area may be divided into a plurality of areas in the Z direction (not shown). The HUD display areas A, A1, and A2 are representative examples of areas used in the head-up display according to the present invention. In this specification, the HUD display area refers to an area on the windshield 20 where the HUD image can be reflected when the HUD image is viewed at any rotational position of the concave mirror from an area assumed to be the driver's viewpoint while driving.

[0023] Fig. 3 is a partial cross-sectional view of the windshield 20 shown in Fig. 2 cut in the XZ direction and viewed from the Y direction. As shown in Fig. 3, the windshield 20 is a laminated glass including a glass plate 210 which is a first glass plate, a glass plate 220 which is a second glass plate, and an interlayer film 230. In the windshield 20, the glass plates 210 and 220 are fixed together with the interlayer film 230 sandwiched therebetween.

[0024] In the windshield 20, which is a laminated glass, the glass plates 210 and 220 have streaks caused by stretching during production. The intermediate film 230 is a film that is located between the glass plates 210 and 220 and bonds the glass plates 210 and 220 together such that the streaks of the glass plate 210 and the streaks of the glass plate 220 are, for example, perpendicular to each other.

[0025] An inner surface 21 of the windshield 20, which is one surface of the glass plate 210 that faces the inside of the vehicle, and an outer surface 22 of the windshield 20, which is one surface of the glass plate 220 that faces the outside of the vehicle, may be either flat or curved.

[0026] When the windshield 20 is attached to a vehicle, the HUD display area A is formed in a wedge shape in cross section whose thickness changes from the bottom end to the top end of the windshield 20, and has a wedge angle of δ. In at least a part of the area in which the cross section of the windshield 20 is wedge-shaped, the value of the wedge angle varies depending on the vertical position. In other words, the area in which the cross section of the windshield 20 is wedge-shaped includes an area with a variable wedge angle.

[0027] The wedge angle δ is the average rate of change in thickness of the windshield 20, calculated by the least squares method from 13 data points within a range of 30 mm in front of and behind a certain point, measured at 5 mm intervals in the vertical direction when the windshield 20 is attached to the vehicle. The inclination of the wedge angle is the average rate of change in the wedge angle calculated by the least squares method within the same range.

[0028] In the windshield 20, the wedge angle of each region is formed by making at least the intermediate film 230 a wedge film, but in addition to this, either one or both of the glass plates 210 and 220 may be formed into a wedge shape.

[0029] When one or both of the glass sheets 210 and 220 are formed into a wedge shape, the conditions for manufacturing by the float method are devised. That is, by adjusting the peripheral speeds of a plurality of rolls arranged at both ends in the width direction of the glass ribbon traveling on the molten metal, the cross section of the glass in the width direction can be made into a concave, convex, or tapered shape, and a portion with an arbitrary thickness change can be cut out.

[0030] The glass plates 210 and 220 each have fine unevenness in the form of stripes parallel to the direction of travel (striations) due to stretching during production by the float method. When used as a windshield for a vehicle, these stripes cause distortion and reduce visibility when viewed horizontally relative to the line of sight of an observer.

[0031] The glass plates 210 and 220 may be made of, for example, inorganic glass such as soda lime glass or aluminosilicate, or organic glass. The thickness of the glass plate 220 located on the outer side of the windshield 20 is preferably 1.8 mm or more and 3 mm or less. If the thickness of the glass plate 220 is thinner than 1.8 mm, the stone chipping performance is reduced, and if it is thicker than 3 mm, it becomes heavy and difficult to mold.

[0032] The thickness of the glass plate 210 located on the inner side of the windshield 20 is preferably 0.3 mm or more and 2.3 mm or less. If the thickness of the glass plate 210 is thinner than 0.3 mm, handling becomes difficult, and if it is thicker than 2.3 mm, it cannot follow the shape of the intermediate film 230, which is a wedge film. The thickness of the glass plate 210 is more preferably 2.0 mm or less, further preferably 1.8 mm or less, and particularly preferably 1.6 mm or less. However, the thickness of each of the glass plates 210 and 220 does not necessarily have to be constant, and the thickness may vary from place to place as necessary.

[0033] The windshield 20 may or may not have a curved shape. However, if the windshield 20 has a curved shape, forming two pieces of glass with particularly deep curves as the glass plates 210 and 220 will result in a difference in shape (mismatch) between the two pieces, which will have a significant effect on the glass quality (e.g., residual stress) after bonding.

[0034] Glass quality (e.g., residual stress) can be maintained by applying a variable wedge angle to the windshield 20 and setting the thickness of the glass sheet 210 to 0.3 mm or more and 2.3 mm or less. Setting the thickness of the glass sheet 210 to 0.3 mm or more and 2.3 mm or less is particularly effective in maintaining glass quality (e.g., residual stress) in deeply curved glass.

[0035] When the windshield 20 has a curved shape, the glass sheets 210 and 220 are bent after being formed by the float method and before being bonded with the interlayer film 230. The bending is performed by softening the glass by heating. The heating temperature of the glass during bending is about 550°C to 700°C.

[0036] Fig. 4 is a cross-sectional view of the windshield 20 shown in Fig. 2 cut in the XZ direction and viewed from the Y direction. When the windshield 20 has a curved shape as shown in Fig. 4, the maximum bending depth D of the windshield 20 is defined as the distance in the direction perpendicular to the straight line La connecting the midpoints of the longer of two pairs of opposite sides of the concave surface 20D of the windshield 20 to the deepest part of the concave surface 20D.

[0037] If the maximum bending depth D of the windshield 20 is 10 mm or more, the streaks can be sufficiently stretched by bending, and visibility can be sufficiently improved. The maximum bending depth D is preferably 12 mm or more, and more preferably 15 mm or more. In addition, the bending radius of the concave surface 20D is preferably greater than 6000 mm. When the bending radius of the concave surface 20D is greater than 6000 mm, the HUD image is less likely to be distorted. The bending radius of the concave surface 20D is more preferably 7000 mm or more, and even more preferably 8000 mm or more.

[0038] The color of each of the glass plates 210 and 220 is not particularly limited as long as it satisfies a range that satisfies a visible light transmittance (Tv)>70%.

[0039] It is also preferable that a shielding layer, known as "black ceramic," be present around the periphery of the windshield 20. This shielding layer is formed by applying black ceramic printing ink to the glass surface and baking it. This shielding layer forms a black opaque layer around the periphery of the windshield 20, and this black opaque layer prevents the resin, such as urethane, that holds the windshield 20 around its periphery from being deteriorated by ultraviolet rays.

[0040] In addition, the outside (the outer surface of the glass plate 220) or the inside (the inner surface of the glass plate 210) of the windshield 20 may have a coating having a water-repellent function, an infrared shielding function, an ultraviolet shielding function, or a visible light reflectance reducing function, or a coating having low radiation characteristics.

[0041] Returning to the explanation of Figure 3, thermoplastic resins are often used as the intermediate film 230 that bonds the glass plates 210 and 220 together, and examples of such thermoplastic resins include plasticized polyvinyl acetal resins, plasticized polyvinyl chloride resins, saturated polyester resins, plasticized saturated polyester resins, polyurethane resins, plasticized polyurethane resins, ethylene-vinyl acetate copolymer resins, and ethylene-ethyl acrylate copolymer resins, which have traditionally been used for this type of application.

[0042] Among these, plasticized polyvinyl acetal resins are preferably used because they provide a good balance of various properties such as transparency, weather resistance, strength, adhesive strength, penetration resistance, impact energy absorption, moisture resistance, heat insulation, and sound insulation. These thermoplastic resins may be used alone or in combination of two or more. The term "plasticized" in the plasticized polyvinyl acetal resin means that the resin is plasticized by adding a plasticizer. The same applies to other plasticized resins.

[0043] Examples of the polyvinyl acetal resin include polyvinyl formal resin obtained by reacting polyvinyl alcohol (hereinafter, sometimes referred to as "PVA" as necessary) with formaldehyde, polyvinyl acetal resin in the narrow sense obtained by reacting PVA with acetaldehyde, and polyvinyl butyral resin (hereinafter, sometimes referred to as "PVB" as necessary) obtained by reacting PVA with n-butylaldehyde. In particular, PVB is preferred because it has an excellent balance of various properties such as transparency, weather resistance, strength, adhesive strength, penetration resistance, impact energy absorption, moisture resistance, heat insulation, and sound insulation. These polyvinyl acetal resins may be used alone or in combination of two or more kinds. However, the material forming the intermediate film 230 is not limited to thermoplastic resins.

[0044] The thickness of the intermediate film 230 is preferably 0.5 mm or more at its thinnest part. If the thickness of the intermediate film 230 is less than 0.5 mm, the necessary penetration resistance as a windshield cannot be ensured. Moreover, the thickness of the intermediate film 230 is preferably 3 mm or less at its thickest part. If the thickness of the intermediate film 230 is thicker than 3 mm, the weight becomes heavy and handling becomes difficult.

[0045] The intermediate film 230 may have an area having a sound insulation function, an infrared shielding function, an ultraviolet shielding function, a shade band (a function for reducing visible light transmittance), etc. The intermediate film 230 may have three or more layers. For example, the intermediate film 230 may be composed of three layers, and the hardness of the middle layer may be lower than the hardness of the layers on both sides, thereby improving the sound insulation. In this case, the hardness of the layers on both sides may be the same or different.

[0046] In this way, when the number of layers of the intermediate film 230 increases, the thickness of each layer changes, and the optical quality, for example, the above-mentioned see-through double image, may further deteriorate. In this case, by setting the thickness of the glass plate 210 to 0.3 mm or more and 2.3 mm or less, the glass plate 210 can easily follow the wedge film of the intermediate film 230, and deterioration of the optical quality can be suppressed. In other words, setting the thickness of the glass plate 210 to 0.3 mm or more and 2.3 mm or less is particularly effective when the number of layers of the intermediate film 230 increases.

[0047] Typically, the light source of the HUD is located at the bottom inside the vehicle cabin, and is projected from there onto the laminated glass. Since the projected image is reflected by the rear and front surfaces of the glass plates 210 and 220, in order to overlap the two reflected images without generating double images, it is necessary for the thickness of the glass to change parallel to the projection direction. If the thickness of the glass plate 210 changes in a direction perpendicular to the streaks, in order to use it as glass onto which information is projected, the streaks must be used in a direction perpendicular to the projection direction, i.e., the streaks must be horizontal to the line of sight of the observer (driver) inside the vehicle cabin, resulting in poor visibility.

[0048] In order to improve visibility, the laminated glass made using the glass plate 210, the glass plate 220, and the interlayer film 230 is arranged so that the streaks of the glass plate 210 and the streaks of the glass plate 220 are perpendicular to each other. With this arrangement, the distortion that would be aggravated by the glass plate 210 alone is alleviated by the presence of the glass plate 220, whose streaks are perpendicular to each other, and the interlayer film 230 that bonds the glass plates 210 and 220, improving visibility.

[0049] If the glass plates 210 and 220 are not wedge glass, the streaks of both the glass plates 210 and 220 are perpendicular to the line of sight of an observer (driver) inside the vehicle, and visibility is not impaired.

[0050] To produce the intermediate film 230, for example, the above-mentioned resin material that will become the intermediate film 230 is appropriately selected and extruded in a heated and molten state using an extruder. The extrusion conditions, such as the extrusion speed of the extruder, are set to be uniform. The extruded resin film is then stretched to give curvature to the upper and lower sides according to the design of the windshield 20, thereby completing the intermediate film 230.

[0051] To produce laminated glass, the stretched interlayer film 230 is sandwiched between glass plates 210 and 220 to form a laminate, and this laminate is then placed in a rubber bag, for example, and bonded at a temperature of about 70 to 110°C in a vacuum of -65 to -100 kPa.

[0052] Furthermore, a laminated glass having superior durability can be obtained by performing a pressure bonding treatment, for example, by heating and pressing under conditions of 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 consideration of simplification of the process and the properties of the material to be filled in the laminated glass.

[0053] In addition to the intermediate film 230, a film or device having functions such as heating, infrared reflection, light emission, power generation, light control, visible light reflection, scattering, decoration, and absorption may be provided between the glass plates 210 and 220.

[0054] FIG. 5 is a diagram illustrating the deviation amount of the wedge angle in the HUD display area. In FIG. 5, the horizontal axis is the distance in the vertical direction (Z direction in FIG. 2) from the bottom end of the HUD display area A, and the vertical axis is the wedge angle. In FIG. 5, a is the wedge angle measurement value at each position in the vertical direction of the HUD display area A, and b is a linear approximation line obtained by approximating the wedge angle measurement value a of the HUD display area A with a linear function, and is obtained by using the least squares method. Also, e is the maximum deviation amount of the wedge angle measurement value a from the linear approximation line b. The maximum deviation amount refers to the maximum deviation amount of the wedge angle measurement value a from the linear approximation line b in the HUD display area.

[0055] The inventors have found that in the optical system of a HUD, when the FOV (Field Of View: viewing angle, hereinafter sometimes simply referred to as FOV) in the vertical direction (Z direction) is 2 degrees or more and when it is less than 2 degrees, the effect that the maximum deviation amount e shown in Fig. 5 has on the value of reflected double images differs. This will be explained with reference to Table 1, which shows the results of a simulation performed by the inventors.

[0056] [Table 1] As shown in Table 1, when the maximum deviation e is 0.25 mrad, the value of the reflected double image is 1.1 min when the FOV is < 2 deg, but doubles to 2.2 min when the FOV is ≥ 2 deg. Also, when the maximum deviation e is 0.2 mrad, the value of the reflected double image is 0.6 min when the FOV is < 2 deg, but doubles to 1.4 min when the FOV is ≥ 2 deg. When the maximum deviation e is 0.15 mrad, the value of the reflected double image is 0.2 min when the FOV is < 2 deg, but is 0.7 min, which is more than three times as long, when the FOV is ≥ 2 deg. The maximum deviation e is more preferably 0.1 mrad or less, and even more preferably 0.05 mrad or less.

[0057] In this way, regardless of the FOV, the greater the maximum deviation e, the greater the value of the reflected double image. Therefore, a smaller maximum deviation e is preferable. Furthermore, when comparing at the same maximum deviation e, the value of the reflected double image when FOV ≧ 2 degrees is more than twice the value of the reflected double image when FOV < 2 degrees, regardless of the value of maximum deviation e. In other words, when FOV ≧ 2 degrees, it is necessary to suppress the maximum deviation e more than when FOV < 2 degrees.

[0058] Generally, a person with the minimum visual acuity of 0.7 (ISO 8596:2009) required for a regular driver's license in Japan will notice a reflected double image if there is a change in the reflected double image of 1.4 minutes. Applying this to Table 1, we can see that when FOV ≧ 2 deg, the maximum deviation e must be 0.2 mrad or less.

[0059] Furthermore, when FOV≧2deg, it is even more preferable that the maximum deviation e is 0.15mrad or less. From Table 1, when FOV≧2deg, the maximum deviation e is 0.15mrad, the value of the reflected double image is 0.7min, which is lower than the resolution of a person with 1.0 visual acuity, and the risk of the viewer noticing the reflected double image can be further reduced. From the viewpoint of expanding the display area of ​​the HUD, the FOV is preferably 2.5deg or more, more preferably 3deg or more, and particularly preferably 4deg or more.

[0060] When FOV≧2 deg, in order to keep the maximum deviation e in FIG. 5 at 0.2 mrad or less, preferably at 0.15 mrad or less, it is important to control the manufacturing conditions of the windshield 20.

[0061] For example, in the windshield 20, when the interlayer 230 is a wedge film and the glass plates 210 and 220 are not formed in a wedge shape, it is sufficient to properly manage the heating temperature and the extrusion speed when extruding the interlayer 230. Also, it is sufficient to properly manage the heating temperature and the extension speed when the interlayer 230 is stretched.

[0062] Furthermore, in the windshield 20, when the interlayer 230 is formed as a wedge film and, in addition, one or both of the glass sheets 210 and 220 are formed into a wedge shape, it is only necessary to properly manage the line speed and temperature in the float when producing the glass sheets 210 and 220. It is also necessary to properly adjust the peripheral speeds of the multiple rolls arranged at both ends of the glass ribbon traveling on the molten metal.

[0063] When the FOV in the vertical direction of the HUD display area is <2 deg, it is preferable to vary the wedge angle of the intermediate film 230 in a range of 1.5 mrad or less, but when the FOV is ≥2 deg, it is preferable to vary the wedge angle of the intermediate film 230 in a range of 0.4 mrad or less. This is because when the FOV in the vertical direction of the HUD display area is ≥2 deg, if the wedge angle of the intermediate film 230 is greater than 0.4 mrad, reflected double images become noticeable. The wedge angle of the intermediate film 230 is more preferably 0.35 mrad or less, even more preferably 0.3 mrad or less, particularly preferably 0.25 mrad or less, particularly preferably 0.2 mrad or less, and particularly preferably 0.1 mrad or less. An additional effect of setting the wedge angle of the intermediate film 230 in the above-mentioned range of 0.4 mrad or less is that reflected double images can be suppressed even when the distance of the HUD image is extended to 5 m, 7 m, 10 m, 20 m, etc. as the viewing angle of the HUD image increases.

[0064] 5 is preferably inclined in a direction in which the wedge angle becomes smaller as it goes from the lower end to the upper end in the vertical direction of the HUD display area, i.e., the linear approximation line is negatively inclined. By using a negatively inclined linear approximation line, even when the concave mirror of the HUD is rotated to match the top or bottom of the driver's viewpoint, reflected double images can be suppressed more than before.

[0065] In this case, the preferred wedge angle profile is that the absolute value of the inclination of the linear approximation line of the wedge angle shown in FIG. 5 is 0.0006 mrad / mm or more and 0.006 mrad / mm or less. If the absolute value of the inclination of the linear approximation line of the wedge angle is greater than 0.0006 mrad / mm, the effect of changing the wedge angle and suppressing the reflected double image is fully exhibited, and if it is less than 0.006 mrad / mm, when the glass follows the shape change, the change is not too sudden and the region does not become distorted. The absolute value of the inclination of the linear approximation line of the wedge angle is more preferably 0.005 mrad / mm or less, even more preferably 0.004 mrad / mm or less, particularly preferably 0.003 mrad / mm or less, and particularly preferably 0.002 mrad / mm or less. Also, the absolute value of the inclination of the linear approximation line of the wedge angle is more preferably 0.001 mrad / mm or more. Furthermore, when the vertical viewing angle is less than 2.5 degrees, it is preferable that the inclination of the linear approximation line of the wedge angle is negative, and when the vertical viewing angle is 2.5 degrees or more, it is preferable that the inclination of the linear approximation line of the wedge angle is positive.

[0066] Furthermore, by setting the absolute value of the slope of the linear approximation line to between 0.0006 mrad / mm and 0.006 mrad / mm, the reflected double image can be kept within the permissible range of ±1.4 min, even when the concave mirror of the HUD is rotated to match the up or down position of the driver's viewpoint.

[0067] Moreover, the absolute value of the inclination of the wedge angle is preferably 0.006 mad / mm or less, more preferably 0.005 mrad / mm or less, even more preferably 0.004 mrad / mm or less, particularly preferably 0.003 mrad / mm or less, and especially preferably 0.002 mrad / mm or less. By having the inclination of the linear approximation line, the maximum deviation amount, and the absolute value of the inclination of the wedge angle within the ranges of the present invention, distortion of the HUD display area is reduced.

[0068] Furthermore, when the maximum deviation is expressed as e [mrad] and the vertical viewing angle is expressed as FOV [deg], it is preferable that e and FOV satisfy the relationship of the following formula (1). As the viewing angle of the HUD image increases, reflected double images become more noticeable, but by satisfying this relationship, the effect of suppressing reflected double images when the viewing angle of the HUD image is large is increased.

[0069] e≦-0.015×FOV+0.23...Equation (1) Furthermore, according to the present invention, in laminated glass having a non-constant wedge angle, reflected double images can be suppressed even when the HUD display area is larger than before. In addition, because the wedge angle is optimized using a linear approximation rather than a non-linear approximation, the actual interlayer film and laminated glass can be easily and stably manufactured.

[0070] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims. [Explanation of symbols]

[0071] 10, 40 light sources 11a, 11b, 12a, 12b, 41a, 41b, 42a, 42b rays 11c, 12c, 41c, 42c statues 20 Windshield 20D concave 21 Inside 22 Exterior 30 eyes 210, 220 Glass plate 230 Interlayer A, A1, A2 HUD display area B Area outside of HUD display δ wedge angle

Claims

1. A laminated glass comprising: a first glass sheet that is disposed on an inside of a vehicle; a second glass sheet that is disposed on an outside of the vehicle; and an interlayer film that is located between the first glass sheet and the second glass sheet and bonds the first glass sheet to the second glass sheet, Equipped with a display area for use in a head-up display, the indication region has a wedge-shaped cross-sectional shape in which a thickness of an upper end side in a vertical direction when the laminated glass is attached to the vehicle is thicker than a lower end side, a wedge angle value varies depending on a position in the vertical direction in at least a portion of the wedge-shaped region; the display area has a viewing angle in the vertical direction of 2 degrees or more, a maximum deviation of the measured value of the wedge angle from a linear approximation line obtained by approximating the measured value of the wedge angle at each position in the vertical direction of the display area with a linear function is 0.2 mrad or less; the linear approximation line is inclined in a direction in which the wedge angle becomes smaller as the view angle in the vertical direction moves from the lower end side to the upper end side when the view angle in the vertical direction is less than 2.5 degrees, and is inclined in a direction in which the wedge angle becomes larger as the view angle in the vertical direction moves from the lower end side to the upper end side when the view angle in the vertical direction is 2.5 degrees or more, the absolute value of the slope of the linear approximation line is 0.0006 mrad / mm or more and 0.006 mrad / mm or less; The laminated glass is characterized in that the wedge angle is 0.4 mrad or less over the entire display area.

2. A laminated glass comprising: a first glass sheet that is disposed on an inside of a vehicle; a second glass sheet that is disposed on an outside of the vehicle; and an interlayer film that is located between the first glass sheet and the second glass sheet and bonds the first glass sheet to the second glass sheet, Equipped with a display area for use in a head-up display, the indication region has a wedge-shaped cross-sectional shape in which a thickness of an upper end side in a vertical direction when the laminated glass is attached to the vehicle is thicker than a lower end side, a wedge angle value varies depending on a position in the vertical direction in at least a portion of the wedge-shaped region; the display area has a viewing angle in the vertical direction of 2 degrees or more, a maximum deviation of the measured value of the wedge angle from a linear approximation line obtained by approximating the measured value of the wedge angle at each position in the vertical direction of the display area with a linear function is 0.2 mrad or less; the linear approximation line is inclined in a direction in which the wedge angle becomes smaller as the view angle in the vertical direction moves from the lower end side to the upper end side when the view angle in the vertical direction is less than 2.5 degrees, and is inclined in a direction in which the wedge angle becomes larger as the view angle in the vertical direction moves from the lower end side to the upper end side when the view angle in the vertical direction is 2.5 degrees or more, the absolute value of the slope of the linear approximation line is 0.0006 mrad / mm or more and 0.006 mrad / mm or less; The laminated glass has a wedge angle of 0.35 mrad or less.

3. 3. The laminated glass according to claim 1, wherein the maximum deviation is 0.15 mrad or less.

4. The laminated glass according to claim 1 , wherein the absolute value of the gradient of the linear approximation line is 0.001 mrad / mm or more.

5. 5. The laminated glass according to claim 1, wherein when the maximum deviation is expressed as e [mrad] and the viewing angle in the vertical direction is expressed as FOV [deg], e and FOV satisfy the relationship "e≦−0.015×FOV+0.23".

6. 6. The laminated glass according to claim 1, wherein the bending radius in the vertical direction is 6000 mm or more.

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