Window glass for vehicles

Abstract

To provide a vehicular window glass which can prevent portions provided with connection terminals from being locally heated to high temperature.SOLUTION: A vehicular window glass according to the invention includes: a glass plate having a first surface and a second surface and curved; a pair of bus bars which are formed on the first surface and respectively arranged along two of sides of the glass plate; multiple heating lines formed on the first surface and arranged in parallel to each other so as to connect the pair of bus bars; and connection terminals respectively arranged at the pair of bus bars. Each of the pair of bus bars has a first area where the connection terminal is disposed and second areas excluding the first area. The first area and the second areas are connected along the side. A width of the first area is the same as a width of the second area or smaller than the width of the second area. A resistance value per unit area of the first area is smaller than a resistance value per unit area of the second area.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a window glass for vehicles.

Background Art

[0002] In general, a rear window of an automobile is formed with a defogger for preventing fogging. The defogger usually includes a pair of bus bars extending along both side edges of the rear window and a plurality of heating wires extending in parallel so as to connect these bus bars. And, connection terminals for applying current are provided on the bus bars (for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, since current is intensively applied to the portion of the bus bar where the connection terminal is attached, the amount of heat generated increases. Therefore, there is a possibility that the portion where the connection terminal is provided becomes locally high in temperature, which may cause problems such as disconnection of the bus bar or peeling of the connection terminal. The present invention has been made to solve this problem, and an object thereof is to provide a window glass for vehicles that can suppress the portion where the connection terminal is provided from becoming locally high in temperature.

Means for Solving the Problems

[0005] The vehicle window glass according to the present invention has a first surface and a second surface, and includes a curved glass plate, a pair of bus bars formed on the first surface and arranged along any two sides of the glass plate respectively, a plurality of heating wires formed on the first surface and arranged in parallel so as to connect the pair of bus bars, and connection terminals arranged on each of the pair of bus bars. Each of the pair of bus bars has a first region where the connection terminal is arranged and a second region other than the first region, the first region and the second region are connected along the side, and the resistance value per unit area of the first region is smaller than the resistance value per unit area of the second region.

[0006] In the above vehicle window glass, the thickness of the first region can be made larger than the thickness of the second region.

[0007] In the above vehicle window glass, the first region and the second region can be formed of different materials, and the resistance value of the material constituting the first region can be made smaller than the resistance value of the material constituting the second region.

[0008] In the above vehicle window glass, the width of the first region can be made substantially the same as the width of the second region or smaller than the width of the second region.

[0009] In the above vehicle window glass, the first surface of the glass plate can form a concave surface.

Advantages of the Invention

[0010] According to the vehicle window glass of the present invention, it is possible to suppress the local high temperature at the location where the connection terminal is provided.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Embodiment for Carrying Out the Invention

[0012] Hereinafter, an embodiment in which the window glass for a vehicle according to the present invention is applied to the rear glass of an automobile will be described with reference to the drawings. FIG. 1 is a plan view of this window glass for a vehicle. As shown in FIG. 1, this window glass for a vehicle includes a glass plate 1 curved to be convex toward the outside of the vehicle, a defroster 2 laminated on the inner surface of the glass plate 1, and a pair of connection terminals 3 attached to the defroster 2 by solder 4. A conductive cable 5 (see FIG. 2) extending from the inside of the vehicle is attached to each connection terminal 3, and the current supplied from the conductive cable 5 is supplied to the defroster 2 through the connection terminal 3. Hereinafter, each member will be described.

[0013] <1. Glass Plate> The glass plate 1 is formed in a rectangular shape, and a known glass plate for an automobile can be used. For example, a heat ray absorbing glass, a general clear glass or green glass, or a UV green glass may be used for the glass plate 1. However, such a glass plate 1 needs to achieve a visible light transmittance in accordance with the safety standards of the country where the automobile is used. For example, the solar radiation absorption rate, visible light transmittance, etc. can be adjusted to meet the safety standards. Hereinafter, an example of the composition of clear glass and an example of the composition of heat ray absorbing glass are shown.

[0014] (Clear Glass) SiO 2 : 70 - 73 mass% Al 2 O 3 : 0.6 - 2.4 mass% CaO: 7 - 12 mass% MgO: 1.0 - 4.5 mass% R 2 O: 13 - 15 mass% (R is an alkali metal) Fe 2 O 3 Converted total iron oxide (T-Fe 2 O 3 ): 0.08 - 0.14 mass%

[0015] (Heat absorbing glass) The composition of heat absorbing glass is, for example, based on the composition of clear glass, Fe 2 O 3 Total iron oxide (T-Fe 2 O 3 ) is 0.4 to 1.3 mass%, and CeO 2 The ratio of TiO is 0 to 2 mass%. 2 The ratio of is 0 to 0.5 mass%, and the glass framework component (mainly SiO 2 Or Al 2 O 3 ) to T-Fe 2 O 3 , CEO 2 and TiO 2 The composition can be reduced by the increase in

[0016] The type of glass plate 1 is not limited to clear glass or heat absorbing glass, and may be appropriately selected depending on the embodiment.

[0017] The thickness of the glass plate 1 according to the present embodiment is not particularly limited. However, from the viewpoint of weight reduction, the thickness of the glass plate 1 is preferably 2.2 to 5.1 mm, more preferably 2.4 to 3.8 mm, and particularly preferably 2.7 to 3.2 mm.

[0018] Furthermore, such glass plate 1 may be a single glass plate, or may be a laminated glass in which an interlayer film such as a resin is sandwiched between a plurality of pieces of glass.

[0019] <2. Defogger> Next, the defogger 2 will be described with reference to Fig. 2. Fig. 2 is a cross-sectional view of a window glass provided with a connection terminal. As shown in Fig. 1, the defogger 2 includes a pair of first and second bus bars 21 and 22 for power supply, which extend in the vertical direction along both side edges of the glass plate 1. In addition, a plurality of heating wires 23 extending in the horizontal direction are arranged in parallel at predetermined intervals between the bus bars 21 and 22.

[0020] Near the center of each of the bus bars 21 and 22, connection terminals 3 (to be described later) are arranged. A current is supplied to the connection terminal 3 attached to the first bus bar 21 via a conductive cable 5, and the connection terminal 3 attached to the second bus bar 22 is grounded via the conductive cable 5. With this configuration, when a current is supplied to the defogger 2, heat for anti-fogging is generated in the heating wire 23.

[0021] Here, each of the bus bars 21 and 22 will be described in detail with reference to FIG. 2. Since both bus bars 21 and 22 have substantially the same configuration, the first bus bar 21 will be described below. As shown in FIGS. 1 and 2, the first bus bar 21 is configured by connecting three regions in a vertical row. That is, from top to bottom, an upper region (second region) 211, a central region (first region) 212, and a lower region (second region) 213 are arranged in a row. Each of the regions 211 to 213 has substantially the same width, and the vertical length of the central region 213 is shorter than that of the upper region 211 and the lower region 213. Also, the thickness of the central region 212 is thicker than that of the upper region 211 and the lower region 213. Then, as will be described later, the connection terminal 3 is fixed to the central region 212 by soldering.

[0022] The thickness of the central region 212 can be an integral multiple, such as 2 times, 3 times, etc., of the thickness of the other regions 211 and 213. Specifically, the thickness of the central region 212 is preferably, for example, 5 to 100 μm, and more preferably 10 to 30 μm. On the other hand, the thickness of the upper region 211 and the lower region 213 is preferably, for example, 3 to 50 μm, and more preferably 5 to 20 μm. The thicknesses of the upper region 211 and the lower region 213 may be the same or different. Also, the thickness of the heating wire 23 is not particularly limited, but can be the same as the thicknesses of the upper region 211 and the lower region 213.

[0023] The length of the central region 212 is not particularly limited, but for example, it can be 5 to 70%, preferably 10 to 50%, more preferably 15 to 25% of the overall length of each bus bar 21, 22.

[0024] Each bus bar 21, 22 and the heating wire 23 are formed, for example, by applying a conductive silver paste, copper paste, or aluminum paste to the inner surface of the glass plate 1 by screen printing or the like and then firing it. However, the materials constituting the defroster 2 are not limited to these materials and can be appropriately selected.

[0025] <3. Connection Terminal> Next, the connection terminal 3 will be described. Hereinafter, the connection terminal 3 attached to the first bus bar 21 will be described, but the connection terminal 3 attached to the second bus bar 22 has the same configuration.

[0026] As shown in FIG. 2, the connection terminal 3 according to this embodiment is integrally formed by bending a conductive material such as a plate-shaped metal, and includes a plate-shaped installation portion 31 installed on the bus bars 21, 22 of the defroster 2. And this installation part 31 is formed in a rectangular shape, and its lower surface is fixed to the central regions 212, 222 of the bus bars 21, 22 via the solder 5.

[0027] The solder 5 can be either lead-free solder or leaded solder. When using lead-free solder, for example, indium-based or bismuth-based lead-free solder can be used.

[0028] At the rear end of the installation portion 31, a plate-shaped upright portion 32 that stands obliquely upward is integrally connected. The upright portion 32 is formed in a rectangular shape and stands at an angle of about 30 degrees with respect to the installation portion 31. Note that the angle of the upright portion 32 with respect to the installation portion 31 is not particularly limited, but for example, it is preferably 10 to 90 degrees.

[0029] And at the upper end of the upright portion 32, a plate-shaped connecting portion 33 extending horizontally rearward is integrally connected. The connecting portion 33 is formed in a rectangular shape in plan view that is narrower than the installation portion 31, and at the rear end thereof, the end of the above-described conductive cable 5 is fixed by an adhesive member 6 such as solder or a conductive adhesive.

[0030] <4. Method for manufacturing window glass> Next, the method for manufacturing the window glass according to the present embodiment will be described. First, the paste for the defroster 2 described above is printed on one surface of the glass plate 1 formed in a flat plate shape. At this time, the paste is printed two or more times in the central regions 212 and 222 of the respective bus bars 21 and 22 to make the thickness larger than that of the upper regions 211 and 221 and the lower regions 213 and 223. Next, the glass plate 1 is carried into a heating furnace, heated to near the softening point, and the paste printed on the glass plate 1 is fired to form the defroster 2. Subsequently, the glass plate 1 carried out from the heating furnace is pressed to bend the glass plate 1 into a desired shape. At this time, the surface on which the defroster 2 is formed becomes a concave surface. Subsequently, after the glass plate 1 is gradually cooled, when the connection terminals 3 are attached to the respective bus bars 21 and 22, the window glass according to the present embodiment is completed. Note that the forming method of the glass plate 1 is not particularly limited, and in addition to the press forming described above, it can be formed by a self-weight bending method or the like in which the glass plate 1 is bent by its own weight.

[0031] <5. Features> As described above, according to the window glass according to the present embodiment, the following effects can be obtained.

[0032] (1) In the bus bars 21 and 22, in the central regions 212 and 222 where the connection terminals 3 are arranged, since current is intensively applied, there is a risk of local overheating. In contrast, in this embodiment, since the thickness of the central regions 212 and 222 where the connection terminals 3 are arranged is increased, the resistance value per unit area of these regions 212 and 222 is decreased. Therefore, even when current is intensively applied, the generated heat can be reduced, so that the central region can be prevented from becoming locally overheated. For example, when the defroger 2 is formed of silver (electrical resistivity: 1.6×10 -8 Ω·m), when the width of the defroger is 30 mm and the thickness of the central regions 212 and 222 is about 20 μm, the resistance value per unit area of the central regions 212 and 222 is about 1.5 Ω / m 2 (the resistance value per unit length of the bus bar is about 0.45 Ω / dm), and the heat generation amount per unit area is 114 W / m 2 becomes. On the other hand, when the thicknesses of the upper regions 211 and 221 and the lower regions 213 and 223 are about 10 μm, the resistance values per unit area of these regions are about 2.0 Ω / m 2 (the resistance value per unit length of the bus bar is about 0.90 Ω / dm), and the heat generation amount per unit area is 152 W / m 2 becomes. Therefore, the heat generation amount per unit area of the central regions 212 and 222 can be made smaller than that of other regions, and local overheating can be suppressed.

[0033] (2) The metals such as silver that make up the bus bars 21 and 22 have a higher heat reflectivity than the glass plate 1, so when heated in a heating furnace, they are less likely to be heated compared to the glass plate 1. Therefore, when slowly cooled, a difference in shrinkage occurs between the bus bars 21 and 22 and the glass plate 1, and distortion occurs in the glass plate 1 in the vicinity of the bus bars 21 and 22, which may cause perspective distortion. In contrast, for example, it is conceivable to widen the width of the region where the connection terminals 3 are provided in the bus bars 21 and 22, but doing so has the problem that the region where perspective distortion occurs becomes wider. Therefore, in the window glass according to the present embodiment, since the widths of the central regions 212 and 222 are made substantially the same as those of the upper regions 211 and 221 and the lower regions 213 and 223, the region where perspective distortion occurs can be reduced. Note that the width of the central regions 212 and 222 may be wider than that of other regions, but even in such a case, if the thickness of the central regions 212 and 222 is made thicker than that of other regions, even when the width of the central regions 212 and 222 is widened, this can be minimized. Therefore, perspective distortion can be suppressed.

[0034] In particular, when heating the surface on which the defroster 2 is formed during press molding, the difference in shrinkage between the glass plate 1 and the defroster 2 becomes large, and the above-described perspective distortion is likely to occur. Therefore, in such a case, the configuration of the bus bars 21 and 22 as in the present embodiment is particularly advantageous.

[0035] <6. Modification Example> As described above, one embodiment of the present invention has been described, but the present invention is not limited to the above embodiment, and various changes are possible without departing from the spirit thereof. And the plurality of modification examples shown below can be combined as appropriate.

[0036] <6-1> In each of the above embodiments, the widths of the central regions 212 and 222 are made the same as those of the upper regions 211 and 221 and the lower regions 213 and 223. However, they do not have to be exactly the same, and even if slightly different, they can be made wider. Also, the widths of the central regions 212 and 222 can be made narrower than the widths of the upper regions 211 and 221 and the lower regions 213 and 223.

[0037] <6-2> In the above embodiment, the unit Length In order to reduce the resistance value per unit of the central regions 212 and 222, the thicknesses of the central regions 212 and 222 are made larger than those of the upper regions 211 and 221 and the lower regions 213 and 223. However, the method of reducing the resistance value per unit area of the central regions 212 and 222 is not limited to this. For example, different materials can be used for the central regions 212 and 222 and the upper regions 211 and 221 and the lower regions 213 and 223. That is, the resistance value of the material constituting the central regions 212 and 222 can be made lower than the resistance value of the material constituting the upper regions 211 and 221 and the lower regions 213 and 223. For example, the central regions 212 and 222 can be formed of silver or copper, and the upper regions 211 and 221 and the lower regions 213 and 223 can be formed of a material with a higher electrical resistivity than silver or copper, such as aluminum or zinc.

[0038] In the above embodiment, the overall thickness of the central regions 212 and 222 to which the connection terminals 3 are attached is made larger than those of the upper regions 211 and 221 and the lower regions 213 and 223. However, it is not necessary to increase the overall thickness of the central regions 212 and 222. For example, only the thickness of the portion to which the connection terminals 3 are attached can be increased, and as a result, it is sufficient if the resistance value per unit area of the central regions 212 and 222 is reduced.

[0039] <6-3> In the bus bars 21 and 22, the position of the region where the connection terminal 3 is provided is not particularly limited. In the above embodiment, a region 212, 222 where the connection terminal 3 is provided is formed between the upper regions 211, 221 and the lower regions 213, 223. For example, the bus bars 21 and 22 may be divided into a plurality of regions, and any one of the regions may be the first region of the present invention where the connection terminal 3 is provided, as long as the resistance per unit area is smaller than that of the other regions.

[0040] <6-4> The configuration of the connection terminal 3 shown in the above embodiment is an example, and various forms can be adopted as long as the current can be applied to the bus bars 21 and 22. Also, the method of supplying current to the connection terminal 3 is not particularly limited. For example, a connector to which a conductive cable is connected can be fixed to the connection terminal 3.

[0041] <6-5> In the above embodiment, an example in which the vehicle window glass of the present invention is applied to the rear glass is shown, but it can also be applied to the side glass. In this case, the side where the bus bar is provided is not particularly limited, and the bus bar may be arranged on any two sides of the side glass, and a plurality of heating wires may be arranged in parallel so as to connect them.

Explanation of Reference Numerals

[0042] 1 Glass plate 21, 22 Bus bars 211, 221 Upper regions (second regions) 212, 222 Central regions (first regions) 213, 223 Lower regions (second regions)

Claims

1. A curved glass plate having a first surface and a second surface, A pair of bus bars formed on the first surface and arranged along any two sides of the glass plate, respectively, A plurality of heating wires formed on the first surface and arranged in parallel so as to connect the pair of bus bars, Connection terminals arranged on each of the pair of bus bars, Comprising, Each of the pair of bus bars has a first region where the connection terminal is arranged and a second region other than the first region, The first region and the second region are connected along the side, The resistance value per unit length of the first region is smaller than the resistance value per unit length of the second region, The vehicle window glass, wherein the thickness of the first region is larger than the thickness of the second region.

2. A curved glass plate having a first surface and a second surface, A pair of bus bars formed on the first surface and arranged along any two sides of the glass plate, respectively, A plurality of heating wires formed on the first surface and arranged in parallel so as to connect the pair of bus bars, Connection terminals arranged on each of the pair of bus bars, Comprising, Each of the pair of bus bars has a first region where the connection terminal is arranged and a second region other than the first region, The first region and the second region are connected along the side, The resistance value per unit length of the first region is smaller than the resistance value per unit length of the second region, The first region and the second region are formed of different materials, The vehicle window glass, wherein the electrical resistivity of the material constituting the first region is smaller than the electrical resistivity of the material constituting the second region.

3. The vehicle window glass according to claim 1 or 2, wherein the width of the first region is substantially the same as the width of the second region or smaller than the width of the second region.

4. The vehicle window glass according to any one of claims 1 to 3, wherein the first surface of the glass plate constitutes a concave surface.

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