Glazing element

Details Glazing element Glazing element

1999-06-18

2002-12-17

Lester, Evelyn A (Department: 2873)

Optical: systems and elements

Optical modulator

Light wave temporal modulation

C359S274000, C359S267000, C359S265000

Reexamination Certificate

active

06496295

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a glazing element, in particular for motor vehicles, trains or aircraft. The glazing element is provided with two panes which enclose an intermediate space. On at least one pane surface facing the intermediate space, a coating buildup is provided having applied thereupon an electrically conductive layer, thereupon an electrochromic layer, thereupon an ion-conductive layer and thereupon an electrocatalytic layer.
STATE OF THE ART
In many areas, such as for example in buildings, motor vehicles, aircraft or trains, an optically switchable glazing element able to regulate solar radiation is desirable. Optically switchable mirrors, switchable optical components or large-surface displays are further examples for use of optically switchable glazing elements.
A known buildup of an optically switchable component comprises a transparent electrode, an electrochromic layer, an ion conductor, a counter electrode as well as another transparent electrode layer. A buildup of this type is, for example, in the article by S. K. Deb in Solar Energy Materials and Solar Cells, 1992.
In order to improve the optical transparency of electrochromic components of this type, suggestions have been made to replace the counter electrode layer by optical materials such as for instance water. Thus since the 70s, a buildup called “Deb cell” has been known, in which the counter electrode is obviated by water that is located inside the ion-conducting layer which is separated by the applied voltage and with the thus formed H
+
-ions the electrochromic layer is colored. For this see the article by S. K. Deb in Proc. 24
th
Electronic Components Conf. (IEEE Washington 1974, pp. 11-14) as well as by C. B. Thomas, P. Lloyd, Microelectronics Vol. 7(3), pp. 29-43 (1976).
The layer buildup described in the abovementioned articles comprises a transparent electrode layer, an electrochromic layer, a water containing ion conductor layer and, as usual in systems of this type, a thin gold layer. The water separated by electrolytic action is subsequently supplied from the air via the gold layer. However, the water content inside the ion-conducting layer and the high electric voltages necessary for water separation lead to low stability of the overall electrochromic elements and very greatly limit its life-time. Thus, for example, there is a risk of chemical reactions inside the layers which can destroy the layer bonding. Moreover, the switching behavior of the known electrochromic elements is greatly dependent on humidity.
Another electrochromic arrangement is disclosed in DE 24 36 174 A1 and describes a layer arrangement, the purpose of which, in particular, is for use In solid state displays. This layer arrangement comprises a transparent electrode, which is applied to a transparent substrate. An, electrochromic layer is applied on the electrode layer on top which an ion-permeable insulator layer is provided. An electrocatalytic layer applied on the ion-permeable insulator layer serves as the counter electrode to the transparent electrode layer. A sponge structure provided on the electrocatalytic layer serves as the reservoir layer for atoms and/or molecules, which are electrolytically dissociated by the predominating potential conditions and the electrically charged ions migrate through the ion-permeable insulator layer into the eletrochromic layer respectively are driven out of it. This printed publication also proposes to introduce essentially water into the sponge structure which delivers H
+
-ions following electrolytic separation. Consequently, with regard to this device, all the drawbacks previously discussed in connection with the “Deb cell” can be mentioned.
Finally U.S. Pat. No. 5,136,419 describes an electrochromic component which is provided with an intermediate space in which a gas mixture comprising inert gases and vapor of higher dielectricity constants, such as for instance a mixture of nitrogen and water vapor. This is particularly pointed out in column 1, lines 65 to 68 as well as column 4, lines 13 to 15. The highly dielectric material, preferably water, is ionized within an electric field. In this case, too, the known component is connected with all the previously discussed drawbacks that are inherent to a “Deb cell”.
U.S. Pat. No. 4,505,538 also describes a type of improved Deb cell which is provided with a gas-filled intermediate space. In col. 5, lines 28 and 29, the printed publication mentions that there must be sufficient moisture in the gas-filled intermediate space so that a sufficient number of protons can be made available due to the moisture. This content and the examples listed in the printed publication indicate that a type of improved “Deb cell” is described which separates water by applying a voltage and injects the forming protons into the electrochromic layer.
DESCRIPTION OF THE INVENTION
The object of the present invention is to improve a glazing element for facing building facades or window systems, in particular for motor vehicles, trains or aircraft, having at least two panes which enclose an intermediate space and on at least one of the panes surfaces facing the intermediate space a coating system being provided having applied to one pane surface an electrically conductive, thereupon an electrochromic, thereupon an ion-conducting and thereupon an electrocatalytic layer applied in such a manner that the drawbacks connected with the use of water are obviated. In particular, the high control voltages to coloring and decoloring the electrochromic as possible layer are obviated. The glazing element should be designed optically transparent, i.e. should not possess any individual layers that subsequently influence the optical transmission properties.
The solution to the object on which the present invention is base is given in claim
1
. Further features that advantageously develop the inventive ideas are the subject matter of the subclaims.
An element of the present invention is to design a glazing element for facing building facades or window systems, in particular for vehicles, trains or aircraft according to the generic part of claim
1
in such a manner that, in addition to the coating buildup in the intermediate space, which is free of water, is solely a reducing or oxidizing gas or a gas mixture comprising a reducing or oxidizing gas and an inert gas is provided and that an electric voltage of less than 1.2 volts is applied between the electrically conductive and the electrocatalytical layer.
The present invention is based on the idea of obviating all intermediate layers which impair the optical transmission properties of the invented glazing element. Instead of the sponge structure described in DE 24 36 174 A1, the present invention provides only a gas atmosphere which preferably comprises a mixture of a reducing gas, such as for instance hydrogen gas and an inert gas, such as for instance argon or nitrogen. An essential aspect of the present invention is that the electrochromic glazing element operates without the use of water. It was possible to demonstrate that the invented system can operate at voltages distinctly below the water separation voltage (1.2 V). In this manner the element can be operated at lower operating voltages so that the lifetime of the glazing element can be increased considerably.
The invented glazing element is provided with two panes which can be made of glass or plastic. On at least one pane surface, which faces the intermediate space between the two panes facing each other, a transparent, electrically conductive layer is applied on which, for its part, electrochromic material, such as for instance wolfram dioxide, molybdenum oxide, titanium oxide, vanadium oxide, chromium oxide, nickel oxide, cerium oxide, niobium oxide, yttrium oxide, or viologene is precipitated. Furthermore, an ion conductor, such as for instance made of aluminum oxide, silicon oxide, tantalum oxide, or a polymer electrolyte or an ion-conducting foil, is applied onto the electrochromic material layer. Finally an electrocatalyt

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