Patent Grant
7034326
The present invention relates to a heat-reflecting windshield. In particular, the present invention relates to a windshield for automobiles that has at least 70% transmittance of visible light and is provided with a device for optically detecting adhering moisture.
In order to reduce a cooling load and to enhance comfort, a heat-reflecting glass sheet is known that reflects infrared rays (i.e., heat-ray) in sunlight. A conventional heat-reflecting glass includes a metal film, a transparent conductive film, or a nitride film. As a film capable of enhancing reflection of infrared rays while keeping a high transmittance of visible light, a heat-reflecting film is known that includes a multi-layered structure of metal oxide/metal/metal oxide.
When an optical device is used in a vehicle provided with a glass sheet that has a heat-reflecting film including a metal film, light from the device is attenuated while passing through the heat-reflecting film. The optical device for a vehicle is, for example, a rain sensor that can optically detect adhering water droplets on the outer surface of a windshield. In the rain sensor, a light-emitting element provided on the inner surface of the windshield emits light, and light reflected from the outer surface of the windshield is received by a light-receiving element provided on the inner surface, whereby the presence/absence of droplets of water on the outer surface is detected based on the intensity of reflected light. In this case, light for detection passes through the heat-reflecting film at least twice. Thus, the sensitivity of detecting water droplets adhering to the surface of the windshield is degraded.
JP 8(1996)-210042 A discloses a window used with a transmitter and/or a receiver that function particularly in an infrared range, wherein an infrared-rays reflecting and/or absorbing layer is disposed on the entire surface of the window excluding a surface region for transmission of the infrared light for the transmitter and/or the receiver. However, JP 8(1996)-210042 A discloses a window used with a communication tool rather than a detecting device.
The present invention provides a heat-reflecting windshield including a laminated glass sheet and a detecting device for optically detecting a target object such as water droplets that has a light-emitting portion and a light-receiving portion. The laminated glass sheet includes a first glass sheet, a heat-reflecting film formed on the first glass sheet, an intermediate film and a second glass sheet. The detecting device is disposed on a main surface of the laminated glass sheet such that the light-emitting element and the light-receiving element are arranged in a predetermined region of the main surface, and the predetermined region is rubbed by a windshield wiper. The heat-reflecting film includes a first dielectric layer, a first metal layer, a second dielectric layer, a second metal layer and a third dielectric layer, and the heat-reflecting film is not formed in the predetermined region.
The present invention also provides a heat-reflecting laminated glass sheet including a first glass sheet, a heat-reflecting film formed on the first glass sheet, an intermediate film and a second glass sheet. A main surface of the laminated glass includes a predetermined region where a detecting device optically detects a target object. The heat-reflecting film includes a first dielectric layer, a first metal layer, a second dielectric layer, a second metal layer and a third dielectric layer, and the heat-reflecting film is not formed in the predetermined region.
The laminated glass sheet of the present invention includes a first glass sheet, a heat-reflecting film formed on the first glass sheet, an intermediate film and a second glass sheet, and the heat-reflecting film includes a first dielectric layer, a first metal layer, a second dielectric layer, a second metal layer and a third dielectric layer. At least one layer selected from the first dielectric layer, the second dielectric layer and the third dielectric layer preferably includes a metal oxide that includes at least one element selected from Al, In, Sn and Zn. The metal oxide may include ITO (Indium Tin Oxide), SnO2, and ZnO At least one selected from the first metal layer and the second metal layer preferably includes Ag.
The laminated glass sheet preferably has a region outside the above-mentioned region where a visible light transmittance is 70% or more. In this second region, a solar transmittance is preferably 40% or less. This region should be a transparent region where the heat-reflecting film is formed. It is preferable that a ceramic mask (ceramic print) is preferably provided on a periphery of the region. The ceramic mask may be provided on the periphery of the windshield to form an opaque framework.
The detecting device may be a rain sensor, a fogging sensor or a rain/fogging sensor in which these two sensors are integrated.
The device may be directly attached to a windshield. The device should be arranged in a region where the device does not obstruct the driver's view.
When a shade band for decreasing a transmittance of light is formed with the ceramic mask, the appearance of a vehicle is improved.
An embodiment of the process for manufacturing the windshield of the present invention is described below.
(1) Glass Cutting
First, a glass sheet is cut into a predetermined shape.
(2) Printing
As shown in
(3) Bending
Successively, the glass sheet having a framework of the ceramic mask (a first glass sheet) and a second glass sheet that is cut into the same shape as that of the first glass sheet are bent into a predetermined windshield shape by sag bending.
(4) Forming a Heat-Reflecting Film
The surface of the bent glass sheet to be disposed outside a vehicle (for example, the first glass sheet) is washed, and the layers for a heat reflecting film are formed successively on the surface. The heat-reflecting film 3 has a five-layered structure in which at least three metal oxide films 31 and at least two metal (Ag) films 32 are stacked alternately as shown in
For example, the first metal oxide layer, a first silver layer, a second metal oxide layer, a second silver layer and a third metal oxide layer are formed in this order on the first glass sheet 21 by an in-line type d.c. sputtering.
To prevent the heat-reflecting film 3 from being formed in a region 33 where a detecting device is attached as shown in
(5) Lamination
Lastly, the glass sheet with a heat-reflecting film thus obtained is attached to the other glass sheet via a PVB film as an intermediate thermoplastic layer to obtain a laminated glass sheet.
A detecting device 4 is attached to the inner surface of the windshield 1 such that a light emitting/receiving portion in the detecting device 4 is positioned in the region 33 where the heat-reflecting film 3 is not formed, more specifically, such that a light-emitting element and a light-receiving element are arranged in the region 33. These elements in the device 4 (not shown in
A laminated glass sheet with a heat-reflecting film was obtained by the above-described method, and a rain sensor was attached to a region where the heat-reflecting film was not formed.
Table 1 shows a film composition of the heat-reflecting film in each example, and Table 2 shows optical characteristics of the laminated glass sheet in each example.
In Example 4, a first metal oxide film in the heat-reflecting film is formed of two layers (SnO2+AZO), a second metal oxide film is formed of three layers (AZO+SnO2+AZO), and a third metal oxide film is formed of two layers (AZO+SnO2). The glass sheet used as a substrate is a clear glass sheet having transmission characteristics as shown in Table 2.
As is understood from Table 2, the laminated glass sheet thus obtained had an excellent sunlight shielding property (i.e., 40% or less of solar transmittance) while having 70% or more of transmittance of visible light. The color of each example was neutral.
The region where the heat-reflecting film is not formed has a different color from that of the other region where the heat-reflecting film is provided, which could be recognized visually. However, the detecting device is attached to an inside of the windshield so that the region is not recognized by sight.
In the region where the heat-reflecting film is not formed, the detecting device is attached directly. Therefore, infrared rays are prevented from being directly incident upon a vehicle from that region.
A gradation with a dot pattern may be provided in a border portion between the ceramic mask on the periphery of the windshield and the transparent region of the windshield. A gradation with a dot pattern may be provided in a border portion between the ceramic mask on the periphery of the region and the transparent region of the windshield.
In the region 41 for the detection by the detecting device 4, a ceramic mask should not be formed. The ceramic mask should provide a transparent region where the light emitted from a detecting device and enters the device detects a target object on the outer surface of the windshield. As shown in
A shade band with a low transmittance of visible light may be provided in an upper portion of the windshield. The shade band may be formed by dying PVB. The shade band should not cover the water-detecting region.
As the detecting device, a rain sensor and a fogging sensor are preferably used. It is efficient to integrate them with each other.
As described above, in the heat-reflecting windshield of the present invention, the heat-reflecting film is not provided in a region where a light-emitting element and a light-receiving element are provided. Therefore, light for the detection does not pass through the heat-reflecting film, which enables detection with good sensitivity to be conducted.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2001-157521 | May 2001 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP02/04982 | 5/23/2002 | WO | 00 | 4/14/2003 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO02/096639 | 12/5/2002 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5620799 | Sauer | Apr 1997 | A |
| 5703568 | Hegyi | Dec 1997 | A |
| 5747170 | Von Alpen et al. | May 1998 | A |
| 6052196 | Pientka et al. | Apr 2000 | A |
| 6153995 | Tanaka | Nov 2000 | A |
| 6492619 | Sol | Dec 2002 | B1 |
| Number | Date | Country |
|---|---|---|
| 8-210042 | Aug 1996 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20030155790 A1 | Aug 2003 | US |
