JP2813426B2 - Transparent heat ray reflection glass of radio wave reflection suppression type - Google Patents

Description

The present invention relates to a transparent heat ray reflective glass having a high architectural design without causing a television radio wave reflection obstacle, and more specifically, a relatively thin high-heat reflective glass on a surface of a glass substrate. The present invention relates to a transparent heat ray reflective glass in which the reflection attenuation of a television wave is increased by forming a resistance SiC film.

[Related Art] In recent years, in order to improve architectural design and reduce cooling load, transparent heat ray reflective glass has been frequently used in buildings such as buildings.
Among them, the high-performance heat-reflective glass is obtained by coating the surface of a glass substrate with a thin film of a metal, a metal oxide, a metal nitride or the like in a vacuum by a sputtering method or the like, and has the following excellent characteristics.

It has a wide variety of colors such as silver, bronze, blue and green, so it has excellent architectural design.

Visible light transmittance of 8-40%, visible light reflectance of 10-45% and good balance of visible light create a comfortable indoor space,
It is also effective in protecting privacy.

Since it exhibits excellent solar radiation blocking performance, it helps to reduce the cooling load.

[Problems to be Solved by the Invention] Conventional high-performance heat-reflective glass uses metal or metal nitride as a coating thin film as described above, and has a low surface resistance. It has a property close to that of a plate and tends to have a low return loss.

For example, a conventional high-performance heat ray reflective glass has a coating thin film having a surface resistance value of 250Ω / □ or less, and the return loss of this glass is 7dB or less in a VHF band and a UHF band. The return loss represents the ratio of the reflected radio wave energy to the incident radio wave energy. The larger the value is, the less the reflection is, and the less likely the ghost failure is. If the return loss of the glass is 7 dB or less in the VHF band and the UHF band as described above, ghost interference of television waves may occur depending on the use environment (especially when used in a large area in a high-rise building).

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a new transparent heat ray reflective glass which does not cause a ghost disturbance of a television wave while maintaining excellent architectural design.

[Means for Solving the Problems] It is said that the transparent heat ray reflective glass does not cause a ghost problem that causes a problem if the return loss is 15 dB or more. Therefore, first, the surface resistance of a thin film that does not cause ghost damage was determined from the theory. As shown in FIG. 4, consider a model in which television waves are incident on glass having a thin film on the back surface. This model can be generally rewritten equivalently to a distributed constant circuit as shown in FIG. The input impedance Z _in as seen from the terminal AB on the right side is expressed by the equation (1).

Further, the specific impedance _A and the propagation constant of the glass are represented by the equations (2) and (3), respectively.

Z ₀ : Impedance of space, Z ₀ = 377Ω j: Imaginary unit: Dielectric constant of glass, = 7-0.1jt: Thickness of glass λ ₀ : Wavelength of radio wave On the other hand, a thin film is a perfect reflector such as a metal plate. Since it does not exist, it is represented by the parallel resistance of R and Z ₀ , and its incident characteristic impedance _B is as shown in equation (4).

As described above, the reflectance に よ る of the glass is represented by equation (5).

Therefore, the return loss η is as shown in equation (6).

η = 20logΓ (6) Here, when the wavelength λ ₀ = 300 cm (frequency f = 100 MHz) and the glass thickness t = 10 mm, in order to obtain the return loss η ≧ 15 dB necessary to prevent ghost interference. Means that the surface resistance of the thin film should be 1000Ω / □ or more.

Thus, as a result of examining a thin film material having a surface resistance value of 1000Ω / □ or more and excellent heat ray reflection performance and architectural design, it was found that a SiC film was useful.

In the present invention, the geometric thickness d is 10
forming a SiC monolayer film with nm ≦ d ≦ 40 nm, or a SiC film with a geometric thickness d of 10 nm ≦ d ≦ 40 nm, and an optical thickness nd of 2
This is a radio-reflection-suppressing transparent heat ray reflective glass in which a two- or three-layer film composed of a transparent dielectric film with nm ≦ nd ≦ 400 nm is formed.

The reason why the thickness of the SiC film is limited to 40 nm or less in the present invention is that, when the thickness exceeds 40 nm, transmitted light becomes yellow to orange, which is not preferable for building windows. When the film thickness distribution is large, particularly when forming a film on a large glass substrate, the color unevenness of the non-film surface reflection color becomes large, which is not desirable from the viewpoint of aesthetics. This is because there is a problem such as an increase in height.

The thickness of the glass substrate is about 6 to 12 mm, the thickness of the SiC film is preferably 20 nm or more, and the film is formed by DC sputtering.
As the low dielectric film, TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , Nb ₂ O _{5 and the} like are preferable.

[Function] Since the SiC thin film formed on the surface of the glass substrate has a surface resistance value of 1000Ω / □ or more and a return loss of 15dB or more with respect to an incident television wave, ghost failure does not substantially occur. . Further, this SiC thin film exhibits excellent heat ray reflection characteristics. Furthermore the following thin film 40nm becomes what the color of the transmitted light is suitable as a window of buildings, in a non-film surface reflection 2 ° visual field C light ^{(JIS Z8729) a * = -5~} + 5, b * = - 5- + 25
It becomes a reflection color of silver to bronze.

The transparent dielectric film is irrelevant to the electrical characteristics, adjusts the color, transmittance, reflectance, etc., and improves the durability.

Example FIG. 1 is a sectional view showing an example of the transparent heat ray reflective glass according to the present invention. This is an example in which a SiC single layer film 12 having a geometric thickness (physical thickness) d of 30 nm is formed on the surface of a glass substrate 10 by a DC sputtering method.

FIG. 3 schematically shows the DC sputtering apparatus used here. An exhaust port 24 provided with a variable valve 22 is formed in a part of the grounded vacuum chamber 20, and connected to a vacuum pump 26 through the exhaust port 24 so that the inside of the vacuum chamber 20 can be depressurized. Further, magnetron cathodes 28a and 28b are provided above the vacuum chamber 20, and are connected to DC power supplies 30a and 30b.
A gas supply pipe 34 having a valve 32 is provided between the magnetron cathodes 28a and 28b so that gas can be supplied into the vacuum chamber 20. Further, each magnetron cathode 28a,
A reciprocable transport belt 36 is arranged below 28b.

First, SiC is attached to the lower surface of the cathode 28a as a target 38a. Then, the washed glass substrate 10 is placed on the substrate holder 40 on the conveyor belt 36, the variable valve 22 is opened, and the pressure in the vacuum chamber 20 is reduced to 5 × 10 ⁻⁶ Torr or less. Next, argon gas is supplied through a gas supply pipe 34, the variable valve 22 is closed, and the pressure in the vacuum chamber 20 is 2 × 10 ⁻³ Torr.
So that Next, a negative voltage of 600 V is applied to the cathode 28a, and the glass substrate 10 is moved below the cathode 28a to form the SiC film 12 on the surface of the glass substrate 10.

The surface resistance of the obtained transparent body was 2 MΩ / □ or more. Transmission is visible light transmittance 30%, 2 ゜ field of view C light (JIS Z872
In 9), a = 1.1 and b = 11.8, and the color became bronze. The non-film surface reflection was L ^* = 71.1, a ^* =-3.4, b ^* = 1.3, which was a silver reflection color.

Example 2 FIG. 2 is a sectional view showing another example of the transparent heat ray reflective glass according to the present invention. A SiC film 16 having a geometric thickness (physical thickness) d of 40 nm on the surface of a glass substrate 14 and an optical thickness n
This is an example in which a TiO ₂ film 18 with d of 12 nm is formed by a DC sputtering method.

The sputtering apparatus used here is also the one shown in FIG. First, SiC is used as the target 38a on the lower surface of the cathode 28a, and Ti is used as the target on the lower surface of the cathode 28b.
Attach as 38b. Then, in the same manner as in Example 1, a 40 nm-thick Si layer was formed as a first layer on the surface of the glass substrate.
Form a C film. Then, the power of the cathode 28a is turned off, the variable valve 22 is opened, the pressure is reduced again to 5 × 10 ⁻⁶ Torr or less, oxygen is introduced from the gas supply pipe 34, the variable valve 22 is closed, and the pressure in the vacuum layer 20 is reduced. 2 × 10 ^-3 Torr. Next, a negative voltage of 500 V is applied to the cathode 28b, and the glass substrate is moved under the cathode 28b, so that the SiC
A TiO ₂ film having an optical thickness of 12 nm is formed as a _second layer on the film.

The parallel resistance of the obtained transparent body was 2 MΩ / □ or more. Transmission is a visible light transmittance of 28%, a = −0 at 2 ° visual field C light.
6, b = 6.8, light pale bronze color. The non-film surface reflection was L ^* = 73.2, a ^* =-4.8, b ^* = 13.2, which was a bronze reflection color.

Example 3 A TiO ₂ film having an optical thickness nd of 12 nm was formed on the surface of a glass substrate,
SiC film with a geometric thickness d of 30 nm and an optical thickness nd of 12 nm
A TiO ₂ film was formed by DC sputtering.

The sputtering method is the same as in the above embodiment. The parallel resistance of the obtained transparent body was 2 MΩ / □ or more. Transmission is visible light transmittance 29%, a = 0.8, b = 8.0 in 2 ゜ visual field C light.
And a pale bronze color. The non-film surface reflection is L ^*
= 73.1, a ^* = -4.3, b ^* = 4.4, indicating a pale yellow-green reflection color.

In the above embodiment, a direct current sputtering method was used as a film forming method. This method is preferable because matching such as high-frequency sputtering is not required, and the film forming speed is large and the cost is advantageous. In addition, a vacuum evaporation method, an ion plating method, an arc evaporation method, a CVD method, or the like may be used. As a transparent dielectric film, SnO ₂ , A
l ₂ O ₃ , ZnO, Bi ₂ O ₃ , ZrO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ , AlN, etc., but TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ is preferred.

[Effects of the Invention] As described above, since the present invention has a configuration in which a thin SiC film is formed on a glass substrate, the surface resistance value is 1000Ω / □ or more, and the return loss is large with respect to incident television waves.
Ghost failure can be prevented from occurring. Also, excellent architectural design and heat ray reflection characteristics can be exhibited.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the transparent heat ray reflective glass according to the present invention, and FIG. 2 is a sectional view showing another embodiment of the present invention. FIG. 3 is an explanatory view of a DC sputtering apparatus suitable for carrying out the present invention. FIG. 4 is an explanatory diagram of a model of radio wave incidence on transparent heat ray reflective glass, and FIG. 5 is an equivalent circuit diagram thereof. 10,14 …… Glass substrate, 12,16 …… SiC film, 18… TiO
₂ membranes.

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein the geometric thickness d is 10 on the surface of the glass substrate.
A radio-reflection-suppressing transparent heat ray reflective glass formed with a SiC single layer film with nm ≦ d ≦ 40 nm. 2. The method according to claim 1, wherein the geometric thickness d is 10 on the surface of the glass substrate.
nm ≦ d ≦ 40 nm SiC film and optical thickness nd is 2 nm ≦ nd ≦ 400 n
A radio-reflection-suppressing transparent heat ray reflective glass having a two- or three-layer film formed of a transparent dielectric film having a thickness of m.