Windshield

Abstract

To provide a windshield which is easily broken in a shorter time when an object with a heavy weight such as a pedestrian collides with it.SOLUTION: A windshield 1 comprises: a glass plate 10; and a stress regulation member 50 laid on the surface of the glass plate 10 and having a thermal expansion coefficient different from that of the glass plate 10. The glass plate 10 has a visible light transmission region 5 that can transmit visible light, and a visible light blocking region 4 disposed around the visible light transmission region 5 and blocking visible light. The stress regulation member 50 is disposed in the visible light transmission region 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a windshield. [Background technology]

[0002] Some automobile windshields are designed to be highly rigid to protect against flying stones, for example (see, for example, Patent Document 1). However, if the windshield's rigidity is increased, the pedestrian will receive a greater impact if the automobile collides with the pedestrian and the pedestrian hits the windshield. Therefore, the windshield described in Patent Document 2 is designed to be easily broken when struck by a heavy object such as a pedestrian. Specifically, the windshield in Patent Document 2 is made more susceptible to breaking when struck by an impact by varying the thickness of the shielding layer located on the outer edge. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-146458 [Patent Document 2] International Publication No. 2022 / 270634 Summary of the Invention [Problem to be solved by the invention]

[0004] When a pedestrian strikes a windshield due to a collision between a vehicle and the pedestrian, the pedestrian is more likely to strike the center of the windshield than the periphery. However, the windshield described in Patent Document 2 has a structure in which the outer edge where the shielding layer is arranged is easily broken, so when a pedestrian strikes the center of the windshield, it may take a long time for the windshield to break. This may result in the windshield not being able to fully suppress the impact on the pedestrian. Therefore, there is room for improvement in windshields to make them more easily broken when struck by a pedestrian or the like.

[0005] In view of the above circumstances, there is a demand for a windshield that is more likely to break in a shorter time when struck by a heavy object such as a pedestrian. [Means for solving the problem]

[0006] A characteristic configuration of the windshield according to the present invention is that it is a windshield whose periphery is fixed to a vehicle, and comprises a glass plate and a stress adjustment member laminated on the surface of the glass plate and having a thermal expansion coefficient different from that of the glass plate, wherein the glass plate has a visible light transmitting region that can transmit visible light, and a visible light blocking region that is provided around the visible light transmitting region and blocks visible light, and the stress adjustment member is arranged in the visible light transmitting region.

[0007] According to this configuration, the glass plate of the windshield has a visible light transmitting region and a visible light blocking region surrounding the visible light transmitting region. A stress adjusting member having a thermal expansion coefficient different from that of the glass plate is laminated and disposed on the visible light transmitting region of the surface of the glass plate. That is, in the windshield, the stress adjusting member having a thermal expansion coefficient different from that of the glass plate is disposed near the center of the glass plate, where pedestrians and the like are likely to collide. In this manner, when a pedestrian or the like collides near the center of the glass plate and tensile or compressive stress acts on the glass plate, the glass plate shifts due to the difference in thermal expansion coefficient between the stress adjusting member and the stress adjusting member. Specifically, the stress adjusting member applies thermal stress to the glass plate, changing the surface compressive stress value of the glass plate. Therefore, the fracture stress of the glass plate is lower in the region where the stress adjusting member is disposed than in other regions. This makes the glass plate more likely to break in a short time, thereby reducing the impact on pedestrians. As a result, pedestrians and the like can be adequately protected in the event of a collision with a vehicle.

[0008] The windshield according to the present invention is characterized in that it is a windshield whose periphery is fixed to a vehicle, and comprises a glass plate and a stress adjustment member laminated on the surface of the glass plate and having a thermal expansion coefficient different from that of the glass plate, and the stress adjustment member is positioned in test area B of the glass plate as specified in JIS R3212 (2015).

[0009] According to this configuration, a windshield glass sheet is laminated with a stress adjustment member having a thermal expansion coefficient different from that of the glass sheet in test region B of the glass sheet as specified in JIS R3212 (2015). This test region B is the area of ​​the glass sheet excluding the outer edge. Therefore, in the windshield, the stress adjustment member, whose thermal expansion coefficient is different from that of the glass sheet, is arranged near the center of the glass sheet, where pedestrians and the like are likely to collide. In this way, when a pedestrian or the like collides near the center of the glass sheet and tensile or compressive stress acts on the glass sheet, the glass sheet shifts due to the difference in thermal expansion coefficient between the stress adjustment member and the stress adjustment member. Specifically, the stress adjustment member applies thermal stress to the glass sheet, changing the surface compressive stress value of the glass sheet. Therefore, the fracture stress of the glass sheet is lower in the region where the stress adjustment member is arranged than in other regions. This makes the glass sheet of the windshield more likely to break in a short time, thereby reducing the impact on pedestrians. As a result, pedestrians and the like can be adequately protected in the event of a collision with a vehicle.

[0010] Another characteristic feature is that the stress adjusting member has a refractive index different from that of the glass plate.

[0011] In the present configuration, the stress adjusting member has a refractive index significantly different from that of the glass plate, making it easier to see. By adjusting the refractive index of the stress adjusting member, it is possible to make the stress adjusting member less visible from outside the glass plate in the wind seal.

[0012] Another characteristic feature is that the glass plate has alternating highly strengthened regions where strengthening has been applied and low strengthened regions where the stress adjustment member is laminated and where the compressive stress is lower than that of the highly strengthened regions.

[0013] According to this configuration, the windshield glass sheet can ensure a predetermined strength in the tempered highly tempered regions, making it possible to protect against, for example, flying stones. In addition, the glass sheet is laminated with stress adjustment members, and low tempered regions with lower compressive stress than the high tempered regions are arranged alternately with the high tempered regions. As a result, even if the position at which a pedestrian hits the glass sheet varies depending on the position, the low tempered regions distributed throughout the glass sheet make the glass sheet more likely to break in a short time. As a result, the windshield can more appropriately protect pedestrians and the like in the event of a collision with a vehicle.

[0014] Another characteristic feature is that the stress adjusting member is disposed on the surface of the glass plate facing the interior of the vehicle.

[0015] When a pedestrian or other object strikes the windshield from the outside of the vehicle, tensile stress acts on the glass plate on the inside of the vehicle. Therefore, in this configuration, a stress adjustment member is placed on the glass plate on the inside of the vehicle. This makes it easier for the glass plate to shift due to the difference in thermal expansion coefficient between the stress adjustment member and the glass plate. As a result, the glass plate of the windshield is more likely to break in a short period of time when struck by a pedestrian or other object.

[0016] Another characteristic configuration is that the glass sheet includes a first glass sheet disposed on the vehicle exterior side, a second glass sheet disposed opposite the first glass sheet and located on the vehicle interior side, and an interlayer film bonding the first glass sheet and the second glass sheet together, wherein the first glass sheet has a first surface located on the vehicle exterior side and a second surface located on the vehicle interior side, and the second glass sheet has a third surface located on the vehicle exterior side and a fourth surface located on the vehicle interior side, both the first glass sheet and the second glass sheet are manufactured by a float process using a tin bath, and a tin oxide concentration on the fourth surface of the second glass sheet is higher than the tin oxide concentration on the third surface.

[0017] According to this configuration, the first and second glass sheets constituting the glass sheet are both manufactured by the float process using a tin bath, and the tin oxide concentration of the fourth surface of the second glass sheet located closer to the interior of the vehicle is higher than the tin oxide concentration of the third surface. That is, in this configuration, the fourth surface of the second glass sheet is the surface that is transported by rollers or the like during production. Here, fine scratches are formed on the fourth surface, which is the transport surface of the second glass sheet, during transport in manufacturing the second glass sheet. Therefore, if the fourth surface of the second glass sheet is the transport surface during glass sheet manufacturing, when a pedestrian or the like collides with the windshield, a tensile force acts on the fine irregularities on the fourth surface, making the glass sheet more likely to break in a short period of time.

[0018] Another characteristic feature is that the glass plate is formed by press molding.

[0019] According to this configuration, the windshield is formed by press-molding the glass plate, and therefore the glass plate can be made more fragile by laminating the stress adjusting member thereon while still ensuring a predetermined strength.

[0020] Another characteristic feature is that the stress adjusting member is disposed on at least one of the second surface of the first glass plate and the fourth surface of the second glass plate.

[0021] When a pedestrian or other object collides with the windshield from the outside of the vehicle, tensile stress acts on the glass plate on the inside of the vehicle. Therefore, in this configuration, a stress adjustment member is placed on at least one of the second surface of the first glass plate and the fourth surface of the second glass plate. This makes it easier for the glass plate to shift due to the difference in thermal expansion coefficient between the stress adjustment member and the glass plate. As a result, the glass plate of the windshield is more likely to break in a short period of time when hit by a pedestrian or other object. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a plan view showing an embodiment of a windshield according to the present invention. [Figure 2]FIG. [Figure 3] 1 is a schematic diagram of a manufacturing process for a windshield. [Figure 4] FIG. 1 is a cross-sectional view showing a first modified example of the first embodiment. [Figure 5] FIG. 10 is a cross-sectional view showing a second modification of the first embodiment. [Figure 6] FIG. 1 is a diagram showing a test method. [Figure 7] FIG. 1 is a diagram showing the shape of a test specimen. [Figure 8] 1 is a graph showing the results of Test Example 1. [Figure 9] 1 is a graph showing the results of Test Example 2. [Figure 10] FIG. 10 is a cross-sectional view showing a second embodiment. [Figure 11] FIG. 10 is a cross-sectional view showing a second modification of the second embodiment. [Figure 12] FIG. 10 is a cross-sectional view showing a third embodiment. [Figure 13] FIG. 10 is a plan view showing a windshield of a reference embodiment. [Figure 14] FIG. 10 is a partial cross-sectional view of a windshield according to a reference embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the windshield according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0024] [First embodiment] As shown in Fig. 1, the windshield 1 according to this embodiment includes a glass sheet 10. As shown in Fig. 2, the glass sheet 10 is configured by arranging a first glass sheet 11 on the vehicle exterior side and a second glass sheet 12 on the vehicle interior side facing each other. The glass sheet 10 is a laminated glass in which the first glass sheet 11 and the second glass sheet 12 are joined together with an interlayer film 13. The interlayer film 13 is configured by an adhesive layer.

[0025] The first glass sheet 11 constituting the glass sheet 10 includes a first surface 21 facing the vehicle exterior and a second surface 22 provided on the back side of the first surface 21, while the second glass sheet 12 includes a third surface 23 facing the second surface 22 and a fourth surface 24 provided on the back side of the third surface 23. The first glass sheet 11 and the second glass sheet 12 are substantially identical in shape and are trapezoidal in plan view. When viewed from the vehicle interior, the glass sheet 10 has an upper side 10a, a lower side 10b, a left side 10c, and a right side 10d, with the upper side 10a being shorter than the lower side 10b (see FIG. 1 ). In the glass sheet 10, the first glass sheet 11 and the second glass sheet 12 may be rectangular.

[0026] Known glass plates can be used for the glass plates 11 and 12. For example, the glass plates 11 and 12 may be heat-absorbing glass, clear glass, green glass, UV-green glass, etc. However, the glass plates 11 and 12 are configured to achieve a visible light transmittance that complies with the safety standards of the country in which the automobile is used.

[0027] The thickness of the glass plate 10 is not particularly limited, but the total thickness of the first glass plate 11 and the second glass plate 12 can be, for example, 2.1 to 6 mm. From the viewpoint of weight reduction, the total thickness of the first glass plate 11 and the second glass plate 12 is preferably 2.4 to 3.8 mm, more preferably 2.6 to 3.4 mm, and particularly preferably 2.7 to 3.2 mm.

[0028] Here, an example of a method for measuring the thickness of a curved glass plate 10 (laminated glass) will be described. First, the measurement positions are two points, one above the other, on a center line extending vertically through the center of the left-right direction of the glass plate 10. The measuring device is not particularly limited, but for example, a thickness gauge such as SM-112 manufactured by Teclock Corporation can be used. During measurement, the curved surface of the glass plate is placed on a flat surface, and the edge of the glass plate is clamped with the thickness gauge to perform the measurement. Note that even when the glass plate is flat, the measurement can be performed in the same way as when it is curved.

[0029] The intermediate film 13 is formed of at least one layer. Specific materials for the intermediate film 13 include polyvinyl butyral resin (PVB), ethylene vinyl acetate resin (EVA), polyvinyl acetal resin, etc., and have adhesive properties and penetration resistance.

[0030] The total thickness of the intermediate film 13 is not particularly limited, but is preferably 0.3 to 6.0 mm, more preferably 0.5 to 4.0 mm, and particularly preferably 0.6 to 2.0 mm.

[0031] A shielding layer 4 (an example of a visible light-shielding region) that blocks the view from outside the vehicle is provided along the peripheral edge of the glass plate 10. The material of the shielding layer 4 may be appropriately selected depending on the embodiment as long as it is capable of blocking the view from outside the vehicle. For example, a dark-colored ceramic such as black, brown, gray, or dark blue may be used. In this embodiment, as shown in FIG. 1 , the shielding layer 4 is formed in an annular shape. The shielding layer 4 includes a peripheral edge portion 41 that is laminated along the entire periphery of the first glass plate 11 and the second glass plate 12, and a rectangular extension portion 42 that is connected to the peripheral edge portion 41 and extends downward from near the center of the upper side 10 a of the glass plate 10.

[0032] An imaging device 2 capable of receiving light from outside the vehicle is attached via a bracket (not shown) or the like inside the automobile to which the glass plate 10 is attached. The imaging device 2 is positioned so that an area approximately in the center near the upper edge 10a of the glass plate 10 falls within the angle of view. A trapezoidal opening 43 is formed in the extension 42 of the shielding layer 4, and the imaging device 2 can capture images of the situation outside the vehicle through the opening 43.

[0033] <Stress adjustment material> As shown in FIGS. 1 and 2 , the windshield 1 includes a glass plate 10 and a stress adjustment member 50 laminated thereon. The stress adjustment member 50 has a thermal expansion coefficient different from that of the glass plate 10. In this embodiment, linear bodies 51 are laminated on the glass plate 10 as the stress adjustment member 50. Specifically, the linear bodies 51 are arranged vertically in the center of the visible light transmission region 5 of the glass plate 10, and are laminated on the fourth surface 24 of the second glass plate 12. The stress adjustment member 50 (linear bodies 51) is formed of, for example, a metal such as silver or ceramic. Specifically, the stress adjustment member 50 (linear bodies 51) is laminated on the surface of the glass plate 10 by printing or baking. Metals and ceramics have a thermal expansion coefficient higher than that of the glass plate 10. The stress adjustment member 50 (linear bodies 51) may be formed of a material having a thermal expansion coefficient lower than that of the glass plate 10. Examples of materials having a thermal expansion coefficient different from that of the glass plate 10 include known AG paste and black ceramic paste.

[0034] The stress adjusting member 50 is preferably made of a translucent material that is difficult to see from the outside. Specifically, the stress adjusting member 50 preferably has a haze of 50% or less, more preferably 30% or less, even more preferably 10% or less, and even more preferably 5% or less. In this way, a material with as low a haze as possible is preferable. Preferably, the stress adjusting member 50 is made of a colorless material (specifically, a material to which no pigment is added). The stress adjusting member 50 includes at least a low-melting-point glass, and the low-melting-point glass material may be, for example, a bismuth borosilicate-based material, a bismuth zinc borosilicate-based material, or a zinc borosilicate-based material.

[0035] Furthermore, the stress adjusting member 50 (linear body 51) has a refractive index different from that of the glass plate 10. In this case, the stress adjusting member 50 (linear body 51) can be seen from outside the glass plate 10. However, by adjusting the refractive index of the stress adjusting member 50, it is possible to make the stress adjusting member 50 in the windshield 1 less visible from outside the glass plate 10.

[0036] To make the stress adjusting member 50 difficult to see from outside the glass plate 10, it is preferable that the difference in refractive index between the stress adjusting member 50 and the surface of the glass plate side with which the stress adjusting member 50 is in contact and the adjacent medium (interlayer film 13) is small. Specifically, the difference in refractive index between the stress adjusting member 50 and the surface of the glass plate side with which the stress adjusting member 50 is in contact and the adjacent medium is preferably 0.5 or less, more preferably 0.2 or less, and even more preferably 0.1 or less.

[0037] If the difference in refractive index between the stress adjusting member 50 and the medium is small, the reflection at the interface between the stress adjusting member 50 and the medium is small, making it difficult to see. In particular, by reducing the difference in refractive index between the stress adjusting member 50 and the intermediate film 13, the stress adjusting member 50 formed on the second surface 22 becomes indistinguishable and less noticeable because the reflection at the interface between the stress adjusting member and the intermediate film 13 is small.

[0038] In order to make the stress adjusting member 50 difficult to see from outside the glass plate 10, it is preferable to make the "refractive index difference between the intermediate film 13 and the stress adjusting member 50" smaller than the "refractive index difference between the glass plate and the stress adjusting member 50."

[0039] The stress adjusting member 50 (linear member 51) has a width parallel to the surface of the glass plate 10 of 1.0 mm or less, preferably 0.5 mm, and more preferably 0.3 mm or less, and a thickness perpendicular to the surface of the glass plate 10 of 0.002 mm or more, preferably 0.05 mm or more. The length of the stress adjusting member 50 (linear member 51) is set according to the vertical width of the glass plate 10, but it is preferable that the stress adjusting member 50 be disposed as close to the upper and lower ends of the glass plate 10 as possible.

[0040] The stress adjusting member 50 does not need to have a width greater than a predetermined size. This is because the stress in a region of the glass plate 10 where the stress adjusting member 50 is disposed differs from the stress in other regions, which could cause the region of the glass plate 10 where the stress adjusting member 50 is disposed to become the starting point of fracture. On the other hand, with regard to the thickness of the stress adjusting member 50, it is preferable that the thickness in the direction perpendicular to the surface of the glass plate 10 is large. This is because a large thickness of the stress adjusting member 50 increases the thermal stress on the glass plate 10. The width of the stress adjusting member 50 is preferably 0.1 mm or more, and the thickness is preferably 0.5 mm or less.

[0041] The stress adjusting member 50 is laminated on the glass plate 10 by a method such as fusion, bonding, firing, or sintering. Here, fusion or bonding refers to heat treating the stress adjusting member 50 to melt a portion of the low-melting point glass frit contained therein and adhere it to the glass plate 10. Note that the lamination method of the stress adjusting member 50 is not particularly limited to the exemplified method as long as the stress adjusting member 50 is laminated so as to change the stress of the glass plate 10.

[0042] The position where the stress adjustment member 50 is laminated on the glass plate 10 is preferably the center of the glass plate 10. Generally, the cross section of the glass plate 10 of a windshield 1 has a convex shape facing the outside of the vehicle. For this reason, laminating a stress adjustment member 50 that reduces stress on the convex portion of the glass plate 10 is effective because it makes the glass plate 10 more susceptible to breakage. Here, the center of the glass plate 10 refers to the portion overlapping with test area A of JIS R3212 (2015) (the portion overlapping with the respective test area A when the driver's seat is assumed to be located on the left or right side). As another example, the central portion of the glass plate 10 refers to a portion that is 1100 mm inward, preferably 200 mm inward, and more preferably 300 mm inward in the left-right direction of the glass plate 10 from the outer edge of the visible light transmission region 5. As another example, the central portion of the glass plate 10 refers to the central region between test region A of JIS R3212 (2015) and a moving region obtained by moving test region A in line symmetry with respect to the center line of the glass plate 10 in the left-right direction of the windshield 1. Note that the stress adjustment member 50 may be laminated in a portion other than the central portion of the glass plate 10 in the windshield 1.

[0043] In this way, the stress adjustment member 50 is arranged on the glass plate 10, and the glass plate 10 has a highly strengthened region H that has been strengthened and a low strengthened region L where the stress adjustment member 50 is arranged and has a lower compressive stress than the high strengthened region H.

[0044] <Glass plate manufacturing equipment> As shown in Fig. 3, a manufacturing line for a glass sheet 10 includes a heating furnace 101 and a forming device 102 arranged in this order from upstream to downstream. A roller conveyor 103 is arranged from the heating furnace 101 to the forming device 102 and downstream thereof, and a first glass sheet 11 (second glass sheet 12) to be processed is transported by the roller conveyor 103. The first glass sheet 11 (second glass sheet 12) is formed into a flat plate shape before being carried into the heating furnace 101. For example, the fourth surface 24 of the second glass sheet 12 is laminated with the above-mentioned shielding layer 4 before being carried into the heating furnace 101. The shielding layer 4 may also be laminated on a surface other than the fourth surface 24 of the second glass sheet 12.

[0045] The heating furnace 101 can have various configurations, but may be, for example, an electric heating furnace. A roller conveyor 103 is arranged inside the heating furnace 101 from upstream to downstream. The forming device 102 is configured to press the glass sheets 11 and 12 using an upper mold 121 and a lower mold 122 to form them into a predetermined shape. The upper mold 121 has a downwardly convex curved shape that covers the entire upper surfaces of the glass sheets 11 and 12 and is configured to be movable up and down. The lower mold 122 is formed in a frame shape that corresponds to the peripheral edges of the glass sheets 11 and 12, and its upper surface has a curved shape that corresponds to the upper mold 121. With this configuration, the glass sheets 11 and 12 are press-formed between the upper mold 121 and the lower mold 122 to form the final curved shape. A roller conveyor 103 is disposed within the frame of the lower mold 122, and this roller conveyor 103 is movable up and down so as to pass through the frame of the lower mold 122.

[0046] <Glass plate manufacturing method> Next, a method for manufacturing the windshield 1 will be described. First, the first glass sheet 11 and the second glass sheet 12 are manufactured. Both the first glass sheet 11 and the second glass sheet 12 are manufactured by a float process using a tin bath. Of both surfaces of the first glass sheet 11 and the second glass sheet 12, the surface facing the tin bath has a higher tin oxide concentration than the surface not facing the tin bath.

[0047] In the windshield 1 of the present embodiment, of the third surface 23 and the fourth surface 24 of the second glass plate 12, the surface with the higher tin oxide concentration is the fourth surface 24, and the surface with the lower tin oxide concentration is the third surface 23. In other words, in the second glass plate 12, the tin oxide concentration of the fourth surface 24 is higher than the tin oxide concentration of the third surface 23.

[0048] In addition, in the windshield 1 of this embodiment, of the first surface 21 and second surface 22 of the first glass plate 11, the surface with the higher tin oxide concentration is the second surface 22, and the surface with the lower tin oxide concentration is the first surface 21.

[0049] Although not shown, in the second glass plate 12, the side with the higher tin oxide concentration may be the third side 23 and the side with the lower tin oxide concentration may be the fourth side 24, and in the first glass plate 11, the side with the higher tin oxide concentration may be the first side 21 and the side with the lower tin oxide concentration may be the second side 22.

[0050] The shielding layer 4 is laminated on the manufactured first glass sheet 11 and second glass sheet 12. Subsequently, these glass sheets 11, 12 are formed so as to be convexly curved toward the vehicle exterior. The curvature of the glass sheets 11, 12 can be performed, for example, by press molding using the above-mentioned manufacturing line.

[0051] After the first glass plate 11 and the second glass plate 12 are formed into a curved shape, a laminate is formed by sandwiching the interlayer film 13 between the first glass plate 11 and the second glass plate 12. The interlayer film 13 has a shape larger than the glass plates 11 and 12.

[0052] Next, this laminate is placed in a rubber bag and pre-bonded at approximately 70 to 110°C while being suctioned under reduced pressure. Other pre-bonding methods are also possible, and the following method can be used. For example, the laminate is heated in an oven at 45 to 65°C. Next, the laminate is pressed with a roll at 0.45 to 0.55 MPa. Subsequently, the laminate is heated again in an oven at 80 to 105°C, and then pressed again with a roll at 0.45 to 0.55 MPa. In this way, the pre-bonding is completed.

[0053] Next, the final bonding is performed. The pre-bonded laminate is subjected to the final bonding in an autoclave, for example, at 8 to 15 atmospheres and 100 to 150°C. Specifically, the final bonding can be performed, for example, under conditions of 14 atmospheres and 135°C. Through the preliminary bonding and final bonding described above, the interlayer film 13 is bonded to each of the glass plates 11, 12. Next, the interlayer film 13 that protrudes from the first glass plate 11 and the second glass plate 12 is cut off.

[0054] [Modification 1 of the First Embodiment] As shown in Fig. 4, the stress adjustment member 50 may be laminated on both the first glass plate 11 and the second glass plate 12. In Fig. 4, the stress adjustment member 50 is laminated on both the second surface 22 and the fourth surface 24 of the second glass plate 12. Although not shown, the stress adjustment member 50 may be laminated on either the first surface 21 of the first glass plate 11 or the third surface 23 or fourth surface 24 of the second glass plate 12, or the stress adjustment member 50 may be laminated on both the second surface 22 of the first glass plate 11 and the third surface 23 of the second glass plate 12.

[0055] [Modification 2 of the First Embodiment] As shown in Fig. 5, a plurality of stress adjustment members 50 may be provided in the visible light transmission region 5. In Fig. 5, a linear member 51, a second linear member 52, a third linear member 53, a fourth linear member 54, and a fifth linear member 55 are provided as the stress adjustment members 50. A plurality of second linear members 52 are provided downward from the upper edge 10a of the glass plate 10. A plurality of third linear members 53 are provided upward from the lower edge 10b of the glass plate 10. A plurality of fourth linear members 54 are provided rightward from the left edge 10c of the glass plate 10. A plurality of fifth linear members 55 are provided leftward from the right edge 10d of the glass plate 10.

[0056] In this way, the stress adjusting members 50 are dispersed in the glass plate 10, and the glass plate 10 is alternately arranged with highly strengthened regions H that have been strengthened and low strengthened regions L where the stress adjusting members 50 are arranged and have a lower compressive stress than the highly strengthened regions H. The stress adjusting members 50 may be arranged only in the visible light transmitting regions 5, or may be arranged continuously in the visible light transmitting regions 5 and the shielding layer 4 (visible light shielding region).

[0057] Although not shown, the stress adjustment member 50 may be laminated on one or both of the first glass plate 11 and the second glass plate 12. When the stress adjustment member 50 is laminated on both the first glass plate 11 and the second glass plate 12, the stress adjustment member 50 may be laminated on either the first surface 21 of the first glass plate 11 or the third surface 23 or the fourth surface 24 of the second glass plate 12, or the stress adjustment member 50 may be laminated on the second surface 22 of the first glass plate 11 and the third surface 23 of the second glass plate 12.

[0058] [Test Example 1] Strength tests were conducted on glass plates on which the stress adjustment member 50 was laminated and on glass plates on which the stress adjustment member 50 was not laminated. Specifically, a ring bending strength test was conducted in accordance with ASTM C1499 and DIN EN1288, as shown in FIG. 6 . In this test, a glass plate was placed on a support ring with a diameter of 40 mm, and a load ring with a diameter of 20 mm was placed on top of that. However, when the stress adjustment member 50 was laminated on the glass plate, the glass plate was placed with the surface on which the stress adjustment member 50 was laminated facing downward (the same applies to Test Example 2 below). Then, a ball placed on the load ring was pressed with a load rod at 1 MPa / s, and the fracture stress when the glass plate broke was measured.

[0059] Five specimens, A to E, were used in the test. Specimens A to E were glass plates measuring 100 mm square and 2 mm thick. As shown in Figure 7, specimen A was a glass plate without any stress adjustment material laminated thereon. Specimen B was a glass plate with ceramic wires (0.5 mm wide, 45 mm long, and 0.01 mm thick) laminated thereon as stress adjustment materials. Specimen C was a glass plate with silver wires (0.5 mm wide, 45 mm long, and 0.01 mm thick) laminated thereon as stress adjustment materials. Specimen D was a glass plate with a ceramic film (0.01 mm thick) laminated over the entire surface. Specimen E was a glass plate with a ceramic film (0.01 mm thick) laminated over the entire surface, and with multiple silver wires (2 mm wide, 45 mm long, and 0.01 mm thick) laminated on top of that.

[0060] The test was conducted 30 times for each of specimens A to E. Figure 8 shows the degree of variation in the fracture stress of specimens A to E. As can be seen from Figure 8, if the median fracture stress of specimen A is 1, the median fracture stress of specimens B to D is approximately 0.6, and that of specimen E is just under 0.4. This proves that laminating silver or ceramic as a stress adjusting member to the glass plate reduces the fracture stress. This indicates that specimens B to E are more likely to break than specimen A when subjected to an impact. When a ball is pressed against the glass plate via the load ring, compressive stress acts on the upper surface of the glass plate and tensile stress acts on the lower surface. At this time, misalignment occurs between the glass plate surface and the silver or ceramic stress adjusting member due to the difference in thermal expansion coefficient, which is thought to be why specimens B to E have lower fracture stress than specimen A.

[0061] Furthermore, looking at the test results in Figure 8, specimens B and C, in which silver or ceramic linear elements were placed as stress adjusting members, and specimen D, in which ceramic was placed over the entire surface as a stress adjusting member, had similar median fracture stress values. This shows that the fragility of a stress adjusting member is not proportional to the area it occupies in relation to the glass plate. In addition, specimen E, in which ceramic was placed over the entire surface as a stress adjusting member and silver linear elements were further laminated, had an even lower median fracture stress than specimens B to D. This shows that increasing the thickness of the stress adjusting member makes the glass plate more fragile.

[0062] [Test Example 2] The test used specimens F, G, and H. Specimens F to H were all laminated glass, with the glass plate corresponding to first glass plate 11 having a thickness of 2.1 mm, the glass plate corresponding to second glass plate 12 having a thickness of 1.6 mm, and the interlayer film 13 having a thickness of 0.76 mm. In specimen F, surfaces with high tin oxide concentrations were arranged on the surface corresponding to the first surface 21 of the first glass plate 11 and the surface corresponding to the third surface 23 of the second glass plate 12. In specimen G, surfaces with high tin oxide concentrations were arranged on the surface corresponding to the first surface 21 of the first glass plate 11 and the surface corresponding to the fourth surface 24 of the second glass plate 12. In specimen H, surfaces with high tin oxide concentrations were arranged on the surface corresponding to the second surface 22 of the first glass plate 11 and the surface corresponding to the fourth surface 24 of the second glass plate 12. Two types of measurements, A and B, were performed on specimens F to H. In measurement A, the HIC value was measured at the center (center of gravity) of the specimen. In measurement B, the HIC value was measured at a position 200 mm to the right of the measurement point A in the left-right direction and at the center position in the up-down direction of the specimen. The fracture stress of specimens F, G, and H was measured using the same device as in Test Example 1, and the HIC values ​​of each specimen were calculated. Here, "HIC" stands for Head Injury Criterion and can be calculated according to a known formula. The HIC value is used as a criterion for head injuries caused by falls, collisions, etc., and it is known that the smaller the HIC value, the less likely head injuries are to occur.

[0063] The test results of Test Example 2 are shown in Figure 9. As shown in Figure 9, the HIC value decreases in the order of test specimen F, test specimen G, and test specimen H. This demonstrates that the HIC value decreases when a surface with a high tin oxide concentration is used for the fourth surface 24 of the second glass plate 12, and further demonstrates that the HIC value decreases significantly when a surface with a high tin oxide concentration is also used for the second surface 22 of the first glass plate 11.

[0064] As described above, the first glass sheet 11 and the second glass sheet 12 of the windshield 1 are both manufactured by the float process using a tin bath. Here, when the first glass sheet 11 and the second glass sheet 12 are removed from a tin bath and transported in the float process, minute scratches (irregularities) are formed by the transport rollers on the surfaces (back surfaces) that come into contact with the transport rollers. As can be seen from the test results of Test Example 2 above, if such scratches are formed on the back surface of the first glass sheet 11 (e.g., the second surface 22) or the back surface of the second glass sheet 12 (e.g., the fourth surface 24), the glass sheet 10 becomes more likely to break. Furthermore, if the windshield 1 has a glass sheet 10 whose left-right length is 2 m or more, the back surfaces (the second surface 22 and the fourth surface 24) of the glass sheet 10 are more likely to be scratched.

[0065] The glass sheets 10 (each of the first glass sheet 11 and the second glass sheet 12) are easily scratched when they are thin (for example, 2 mm or less). This is because a thinner glass sheet 10 requires a faster conveyance speed, which increases the rotation speed of the conveying rollers. Furthermore, in a manufacturing process in which the conveyance distance by the rollers is longer than the distance traveled in the tin bath, scratches are more likely to occur on the back surface of the glass sheet 10. In particular, if the glass sheet 10 is adhered with tin so that the direction of movement in the tin bath is the vertical (up-down) direction of the glass sheet 10 of the windshield 1 in order to reduce optical distortion caused by the tin bath, scratches on the glass sheet 10 are formed in a manner that flows vertically (up-down) relative to the glass sheet 10. Furthermore, because deformation in the horizontal (left-right) direction, in which the sides of the glass sheet 10 of the windshield 1 are longer, is greater than deformation in the vertical (up-down) direction, the glass sheet 10 of the windshield 1 is more likely to break.

[0066] Second Embodiment As shown in FIG. 10 , in the second embodiment, the windshield 1 has a stress adjustment member 50 laminated in a test region B of the glass plate 10 as defined by JIS R3212 (2015). In this embodiment, a linear body 51 is laminated in the test region B of the glass plate 10 as the stress adjustment member 50. The test region B is located on the inner circumferential side of the shielding layer 4 (visible light shielding region), and excludes a predetermined width from the inner portion of the shielding layer 4. Therefore, in the example shown in FIG. 10 , the test region B is smaller than the visible light transmitting region 5. Specifically, the linear body 51 is arranged in the vertical direction in the central portion of the test region B defined on the glass plate 10, and is laminated on the fourth surface 24 of the second glass plate 12. The other configurations are the same as those of the first embodiment.

[0067] [Modification 1 of the second embodiment] Although not shown, the stress adjustment member 50 may be laminated on both the first glass plate 11 and the second glass plate 12. For example, in the windshield 1, the stress adjustment member 50 may be laminated on both the second surface 22 and the fourth surface 24 of the second glass plate 12. Alternatively, the stress adjustment member 50 may be laminated on either the first surface 21 of the first glass plate 11 or the third surface 23 or fourth surface 24 of the second glass plate 12, or the stress adjustment member 50 may be laminated on both the second surface 22 of the first glass plate 11 and the third surface 23 of the second glass plate 12.

[0068] [Modification 2 of the second embodiment] As shown in Fig. 11, a plurality of stress adjusting members 50 may be provided in the test area B. In Fig. 11, a linear member 51, a second linear member 52, a third linear member 53, a fourth linear member 54, and a fifth linear member 55 are provided as the stress adjusting members 50. A plurality of second linear members 52 are provided downward from the upper edge 10a of the glass plate 10. A plurality of third linear members 53 are provided upward from the lower edge 10b of the glass plate 10. A plurality of fourth linear members 54 are provided rightward from the left edge 10c of the glass plate 10. A plurality of fifth linear members 55 are provided leftward from the right edge 10d of the glass plate 10.

[0069] In this way, the stress adjusting members 50 are dispersed in the glass plate 10, and the glass plate 10 is alternately arranged with highly strengthened regions H that have been strengthened and low strengthened regions L where the stress adjusting members 50 are arranged and which have a lower compressive stress than the highly strengthened regions H.

[0070] Although not shown, the stress adjustment member 50 may be laminated on one or both of the first glass plate 11 and the second glass plate 12. When the stress adjustment member 50 is laminated on both the first glass plate 11 and the second glass plate 12, the stress adjustment member 50 may be laminated on either the first surface 21 of the first glass plate 11 or the third surface 23 or the fourth surface 24 of the second glass plate 12, or the stress adjustment member 50 may be laminated on the second surface 22 of the first glass plate 11 and the third surface 23 of the second glass plate 12.

[0071] Third Embodiment 12, the windshield 1 may be configured with a single glass plate 10. The other configurations are the same as those of the first embodiment.

[0072] [Reference form] A reference embodiment will now be described. As shown in Fig. 13, a windshield 1 according to the reference embodiment includes a glass sheet 10. As shown in Fig. 14, the glass sheet 10 is configured by arranging a first glass sheet 11 on the vehicle exterior side and a second glass sheet 12 on the vehicle interior side facing each other. The glass sheet 10 is a laminated glass in which the first glass sheet 11 and the second glass sheet 12 are joined together with an interlayer film 13. The interlayer film 13 is configured with an adhesive layer. However, unlike the above-described embodiment, the reference embodiment does not include a stress adjustment member 50 laminated on the glass sheet 10.

[0073] The reference embodiment is characterized in that the fourth surface 24 of the second glass sheet 12 facing the vehicle interior side has a higher tin oxide concentration than the third surface 23 facing the vehicle exterior side, and the fourth surface 24 has fine irregularities. In the example shown in Fig. 14 , the second surface 22 of the first glass sheet 11 facing the vehicle interior side has a higher tin oxide concentration than the first surface 21 facing the vehicle exterior side, and the second surface 22 also has fine irregularities, similar to the fourth surface 24. Although not shown, the second glass sheet 12 may be configured so that the fourth surface 24 facing the vehicle interior side has a higher tin oxide concentration than the third surface 23 facing the vehicle exterior side, and the first surface 21 of the first glass sheet 11 has a higher tin oxide concentration than the second surface 22. The other configurations are the same as those of the first embodiment.

[0074] Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible without departing from the spirit of the present invention. Note that the following other embodiments can be appropriately combined.

[0075] (1) In the above embodiment, the stress adjusting members 50 are disposed on the surface of the glass plate 10 facing the interior of the vehicle. However, the stress adjusting members 50 may be disposed on the surface facing the exterior of the vehicle.

[0076] (2) In the above embodiment, an example is shown in which an opening 43 for the imaging device 2 is formed in the shielding layer 4, but in a configuration in which the imaging device 2 is not used, the shielding layer 4 can be configured without the extension portion 42 and the opening 43.

[0077] (3) In the above embodiment, the shielding layer 4 is formed in a ring shape on the outer edge of the glass plate 10 in the windshield 1, but the shape of the shielding layer 4 may be other than a ring shape and is not particularly limited.

[0078] (4) The above embodiment has been described using as an example a windshield 1 that includes a region captured by the imaging device 2. The windshield 1 can also be used in a windshield in which the glass plate 10 is used as a head-up display (HUD) or in a windshield in which the glass plate 10 extends to the top or sides of the vehicle to ensure a wide visible light transmission region 5. For these windshields, the glass plate needs to be curved with precision, so press forming is preferred over gravity bending. Therefore, although the glass plate of the windshield is strengthened by press forming, laminating a stress adjustment member on the glass plate can adjust the degree of strengthening at desired locations on the glass plate to make it more susceptible to breaking. [Industrial Applicability]

[0079] The present invention is widely applicable to windshields. [Explanation of symbols]

[0080] 1: Windshield 4: Shielding layer (visible light shielding area) 5:Visible light transmission area 10: Glass plate 11: First glass plate 12: Second glass plate 13: Interlayer 21: 1st page 22:Second side 23:Third side 24:Side 4 50: Stress adjusting member B: Test area H: Highly strengthened area L: Low reinforcement area

Claims

1. A windshield whose periphery is fixed to a vehicle, A glass plate and a stress adjusting member laminated on the surface of the glass plate and having a thermal expansion coefficient different from that of the glass plate; the glass plate has a visible light transmitting region through which visible light can pass, and a visible light blocking region provided around the visible light transmitting region and blocking visible light, The stress adjusting member is disposed in the visible light transmitting area.

2. A windshield whose periphery is fixed to a vehicle, A glass plate and a stress adjusting member laminated on the surface of the glass plate and having a thermal expansion coefficient different from that of the glass plate; The windshield, wherein the stress adjustment member is arranged in a test area B of the glass plate defined in JIS R3212 (2015).

3. 3. The windshield according to claim 1, wherein the stress adjusting member further has a refractive index different from that of the glass plate.

4. 3. The windshield according to claim 1, wherein the glass plate has alternating highly tempered regions and low tempered regions in which the stress adjusting member is laminated and in which the compressive stress is lower than that of the highly tempered regions.

5. The windshield according to claim 1 or 2, wherein the stress adjusting member is disposed on a surface of the glass plate facing an interior side of the vehicle.

6. the glass sheets include a first glass sheet disposed on the vehicle exterior side, a second glass sheet disposed opposite the first glass sheet and located on the vehicle interior side, and an interlayer film bonding the first glass sheet and the second glass sheet together, the first glass plate has a first surface located on the vehicle exterior side and a second surface located on the vehicle interior side, the second glass plate has a third surface located on the vehicle exterior side and a fourth surface located on the vehicle interior side, the first glass sheet and the second glass sheet are both produced by a float process using a tin bath, 3. The windshield according to claim 1, wherein the fourth surface of the second glass sheet has a higher tin oxide concentration than the third surface of the second glass sheet.

7. 3. The windshield according to claim 1, wherein the glass plate is formed by press molding.

8. The windshield according to claim 5, wherein the glass plate is formed by press molding.

9. The windshield according to claim 6 , wherein the stress adjusting member is disposed on at least one of the second surface of the first glass plate and the fourth surface of the second glass plate.

Images