JPH0584546U - Window glass with conductive film for heat generation - Google Patents

Abstract

(57) [Summary] [Object] To provide a window glass with a conductive film for heat generation, which has a uniform distribution of heat generation temperature, is suitable for mass production, and has a good appearance. [Configuration] Left and right sides 2 of the window glass 2 whose side length is not short or long
Conductive electrodes 3a and 3b are formed along a and 2b, and a transparent conductive film 4 for heat generation is coated on the window glass 2 between the conductive electrodes 2a and 2b. At this time, the film thickness on the upper side 2a side of the window glass 2 is made thinner than the other regions to form the high resistance region 5.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement in a window glass for automobiles or the like, which is provided with a conductive film for heat generation for defrosting or defrosting.

[0002]

[Prior Art]

 BACKGROUND ART A window glass with a heating film is known in which a window glass for an automobile or the like is coated with a transparent conductive film, and when it is energized, heat is generated to remove the fog and ice on the window glass surface.

FIG. 3 is an explanatory diagram showing a heat generation temperature distribution of a conventional window glass with a conductive film for heat generation. The window glass used in an automobile or the like generally has an upper side shorter than a lower side. For this reason, like the window glass 101 with a conductive film for heat generation shown in FIG. 3A, energizing electrodes (bus bars) 103a and 103b are provided parallel to the upper and lower sides of the window glass 102, and these energizing electrodes 103a , 103b, when the transparent conductive film 104 is applied so that the film thickness thereof becomes substantially uniform, both end portions 105, 105 of the energizing electrode 103a on the upper side have a high temperature. For example, when 1500 watts of electricity per square meter is supplied to the transparent conductive film 104 for about 10 minutes, if a temperature rise of about 20 ° C. is obtained in the central portion of the window glass 101, the upper corner portion is higher than the central portion. The temperature may rise to about 50 ° C or higher.

As in the window glass with conductive film for heat generation 111 shown in FIG. 3B, energizing electrodes 113a and 113b are formed along the left and right sides of the window glass 112, and these energizing electrodes 113a and 113b are formed. Even when the transparent conductive film 114 is coated over the space, the upper side corner portions 115, 115 are heated to a high temperature due to energization.

This is because when the energizing electrodes 103a, 103b, 113a, 113b are arranged along the shapes of the substantially trapezoidal window glasses 102, 112, the current density at the upper corners becomes high.

Therefore, in US Pat. No. 4,543,466, the ratio of the long side to the short side of the current-carrying electrode is regulated, and in Japanese Utility Model Publication No. 45-13979, a guide line is provided in the conductive film to set a current path. A technique for preventing local concentration of electric current and making temperature distribution due to heat generation uniform by regulating is disclosed. Further, the applicant of the present application has disclosed in Japanese Patent Application Laid-Open No. 62-172660 that a slit is formed in a transparent conductive film adhered between the left and right energizing electrodes (bus bars) to regulate the flow of current. Then, we proposed a technology to make the temperature distribution due to heat generation close to a uniform value.

[0007]

[Problems to be solved by the device]

 However, the configuration in which the ratio of the long side to the short side of the current-carrying electrode is regulated (for example, the ratio of the upper and lower bus bars is within ± 15%) may not be satisfied depending on the outer dimensions of the window glass. ..

On the other hand, a configuration in which a guide line portion that regulates a current path or a slit that blocks a current flow is provided in the transparent conductive film is not suitable for mass production because the processing process becomes complicated. In addition, the guide lines and slits are visible, which is not desirable in appearance. Furthermore, although the width is narrow, the part where current does not flow, that is, the part that does not generate heat is positively formed, so there is a problem that defrosting and defrosting of that part will be delayed.

The present invention has been made to solve such a problem, and an object thereof is to provide a window glass with a conductive film for heat generation, which has a uniform distribution of heat generation temperature, is suitable for mass production, and has a good appearance. To do.

[0010]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, a window glass with a conductive film for heat generation according to the present invention is provided with energizing electrodes along opposite sides of the window glass whose side lengths are not short or long, and extends between opposing energizing electrodes. The conductive film for heat generation is deposited and formed, and the film thickness on the short side of the window glass is made thinner than the film thickness of the conductive film in the portion connected to the current-carrying electrode.

It is preferable that the thin portion is formed so as not to contact the current-carrying electrode.

Further, it is desirable that the heat-conducting conductive film is formed such that its film thickness becomes thinner continuously or stepwise as it approaches the short side of the window glass.

Further, it is desirable that the region where the film thickness of the heat generating conductive film is changed substantially overlaps the sunshade region of the window glass.

[0014]

[Action]

 The side with a short side length is described as an upper side, the side with a long side length as a lower side, and the sides having a short side length and non-long side lengths as sides. When the current-carrying electrodes are formed along the sides and, for example, a transparent conductive film is formed between the current-carrying electrodes with a uniform film thickness, the distance between the upper parts of the current-carrying electrodes is higher than that between the lower parts of the current-carrying electrodes. Since the interval is short, the current density of the energizing current is high, and the upper side of the energizing electrode, that is, the corner portion of the upper side becomes hot. When the film thickness of the conductive film is reduced along the upper side, the resistance value of the conductive film is increased in this part (high resistance), so that the current density on the upper side is made approximately equal to the current density on the central part and the lower side. It is possible to eliminate the high temperature region at the upper corner portion of the window glass, and to make the heat generation temperature distribution uniform.

When the thin high-resistance portion is applied to the upper part of the current-carrying electrode, a current-carrying abnormality may occur in which the boundary between the current-carrying electrode and the conductive film for heat generation is abnormally heated. If an abnormal current flow occurs at one location, the abnormal current flow part will spread continuously like a squib, which may cause a major problem, for example, poor current flow. However, the thickness of the conductive film in the area connected to the current-carrying electrode should be reduced. Not doing so (with a low resistance value) can prevent such abnormalities in energization.

When the film thickness of the conductive film is changed, the transmittance and the reflectance may be different from each other, which may cause color unevenness. However, if the region where the film thickness is changed overlaps with the sunshade portion, the color is changed. Unevenness becomes difficult to visually recognize, and the appearance becomes good.

[0017]

【Example】

 An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a structural view of a window glass with a conductive film for heat generation according to the present invention. The window glass 1 with the conductive film for heat generation has electrodes 3a and 3b for energization formed along the left and right sides 2a and 2b of the window glass 2 and the window glass 2 extending between these electrodes 3a and 3b for energization. It is composed of a transparent conductive film 4 for heat generation, which is adhered and formed (coated).

In this embodiment, the transparent conductive film 4 has a three-layer structure in which an indium oxide film, a silver film and an indium oxide film are sequentially formed on the window glass 2 by a sputtering method. The target material is provided about 30 cm away from the surface of the window glass 2 which is curved according to the shape of the window frame of the automobile, and sputtering is performed. At this time, the high resistance region shown by hatching in FIG. 1 is formed. A shielding plate is placed about 3 cm away from the part to be covered. Then, the conditions such as the sputtering time are controlled so that the film thickness on the lower side 2d side as well as the central portion of the window glass not provided with the shield plate becomes a desired value. By providing the shielding plate, the thickness of the window glass surface facing the shielding plate becomes thin.

Specifically, an indium oxide film is first formed on the surface of the window glass 2 (on a portion where the shielding plate is not provided) to a film thickness of about 400 Å by using a vacuum sputtering method, and then a silver film is formed on the film. The conductive film having a resistance value of about 7 Ω □ is formed by forming the indium oxide film with a thickness of about 120 Å and the film thickness of about 400 Å again. The film thickness of the region where the shield plate is provided is thinner than the above value, and by providing the shield plate at a position about 3 cm away from the surface of the window glass 2, the resistance value of the high resistance region 5 is not shielded. It is about 1.3 to 1.5 times the value. The shape of the shielding plate is devised so that the high resistance region 5 does not cover the energizing electrodes 3a and 3b.

FIG. 2 is an explanatory diagram showing the measurement results of the heat generation temperature of the window glass with a heat-generating conductive film according to the present invention. FIG. 2A shows the temperature distribution of the window glass 1 with a conductive film for heat generation shown in FIG. 1, and FIG. 2B shows the case where the high resistance region 5 having a small film thickness is not formed (the conventional conductive film for heat generation is used). It shows the temperature distribution (corresponding to a windowed glass with a membrane). The temperature was measured after supplying 1500 watts of power per square meter for 5 minutes. The room temperature at the time of measurement is 23.8 ° C.

In the window glass 1 with the conductive film for heat generation according to the present invention, the temperature difference between the central portion D and the corner portion A on the upper side 2c side is 8.4 ° C. Is 23 ° C. Therefore, the heating temperature distribution can be made uniform by reducing the film thickness toward the upper side 2c and forming the high resistance region 5.

[0022]

[Effect of the device]

 As described above, in the window glass with the heat-conducting conductive film according to the present invention, the energizing electrodes are formed along the opposite sides whose sides are not short or long, and the energizing electrodes are provided between these energizing electrodes. Since the film thickness of the heat generating conductive film to be coated on the window glass is made thinner toward the short side of the window glass and the high resistance region is formed in the heat generating conductive film, the current density on the short side of the window glass is reduced. Since the rise in temperature is prevented, it is possible to suppress the temperature rise of the upper side of the window glass and to make the heat generation temperature distribution uniform.

Further, by making the region where the film thickness of the conductive film is changed and the sunshade region of the window glass substantially overlap with each other, the color unevenness caused by the difference in the transmittance and the reflectance due to the change in the film thickness. Etc. are hard to see and the appearance is good.

[Brief description of drawings]

FIG. 1 is a structural view of a window glass with a conductive film for heat generation according to the present invention.

FIG. 2 is an explanatory view showing a measurement result of a heat generation temperature of a window glass with a conductive film for heat generation according to the present invention.

FIG. 3 is an explanatory view showing a heat generation temperature distribution of a conventional window glass with a conductive film for heat generation.

[Explanation of symbols]

 1 window glass with conductive film for heat generation 2 window glass 3a, 3b electrode for energization 4 transparent conductive film for heat generation 5 high resistance region with thin film thickness

Claims (4)

[Scope of utility model registration request] 1. A window glass is provided with energizing electrodes along opposite sides whose sides are not short or long, and a conductive film for heat generation is adhered between opposing energizing electrodes, and the energizing is performed. A window glass with a conductive film for heat generation, characterized in that the film thickness on the short side of the window glass is thinner than the film thickness of the conductive film at the portion connected to the electrode for heating. 2. The thin portion of the conductive film for heat generation is
The window glass with a conductive film for heat generation according to claim 1, wherein the window glass is formed so that it does not cover the current-carrying electrodes. 3. The heat-conducting conductive film according to claim 1, wherein the heat-conducting conductive film is configured such that its film thickness is reduced continuously or stepwise as it approaches the short side of the window glass. Window glass with a film. 4. The window glass with a conductive film for heat generation according to claim 1, wherein the region for changing the film thickness of the conductive film for heat generation substantially overlaps with the sunshade region of the window glass.