RF Shielding for Aircraft Windows
A window includes a pane and a geometrically patterned grid. The grid is embedded in the pane and the grid comprises an electrically conductive material and is operable to attenuate radio frequency (RF) energy.
CROSS REFERENCES TO RELATED APPLICATIONS
This is a continuation of U.S. application Ser. No. 11/187,062, now U.S. Pat. No. 7,350,753, filed on Jul. 21, 2005, which is hereby incorporated herein by reference in its entirety.
FIELD OF INVENTION
This relates to improvements in window units installed in aircraft of all types. Specifically, this relates to aircraft windows capable of shielding against the transmission of radio frequency (RF) energy.
The increasing usage of cellular telephones and other wireless electronic devices generally has given rise to a demand for the use such devices by passengers while traveling in aircraft. In most commercial aircraft, however, the passengers are prohibited from using these wireless devices, since their use interferes with services outside the aircraft. When activated on board aircraft, cellular telephones will actively try, and sometimes succeed, in communicating via ground based cellular infrastructure. This is undesirable, and not allowed by government regulations.
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There is a need, therefore, for improved aircraft windows that are transparent to electromagnetic energy in the visible spectrum, yet opaque to RF energy.
SUMMARY OF THE ILLUSTRATED EMBODIMENTS
Disclosed is an improved aircraft window, where RF shielding is desirable. In one embodiment, a window shield comprises an electrically conductive, transparent flexible film, which is applied by known processes to a window pane. This shield is grounded to the aircraft frame or exterior by a “tail” of conductive material, which is secured to a ground point in the vicinity of the window pane.
In an alternative embodiment, a window pane may support elements of conductive material embedded in the pane which are formed into patterns such as grids, that are adapted to absorb energy at the wavelengths emitted by cell phones, or to absorb other radiation.
Embodiments of the present invention therefore allow visible light to pass through an aircraft window while shielding certain other electromagnetic energy. The improved window will facilitate use of certain electronic devices within the aircraft, without interference being caused by or to other signals, outside the plane.
There are additional aspects to the present invention. It should therefore be understood that the preceding is merely a brief summary of some, embodiments and aspects of the present inventions. Additional embodiments and aspects of the present inventions are referenced below. It should further be understood that numerous changes to the disclosed embodiments can be made without departing from the spirit or scope of the inventions. The preceding summary therefore is not meant to limit the scope of the inventions. Rather, the scope of the inventions is to be determined by appended claims and their equivalents.
BRIEF DESCRIPTION OF THE DRAWINGS
These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. It is understood that other embodiments may be utilized and structural and operational changes maybe made without departing from the scope of the present invention.
In order to better attenuate the RF energy, the film 32 is electrically grounded. This electrical grounding is accomplished by a pigtail of the same material (not shown), extending outwardly from a point on the perimeter of the film 32, and attached by conductive adhesive to any convenient nearby point that is electrically connected to the skin of the aircraft, but usually the inside of the skin of the aircraft itself. In alternative embodiments, however, electrical grounding can be accomplished by other means known in the art. For purposes of this application, and in view of the use of embodiments of the invention in the context of an aircraft that is airborne, reference herein to ground and to electrical grounding includes making an electrical connection to the conductive skin of an aircraft while it is airborne.
The film 32 can be applied to the inner surface 28 by any of at least two methods. One involves moistening the film on the side to be applied to the window, then positioning the film and applying pressure with a roller to ensure close contact between the film and the glass. Another method is to use a film that is already coated on one side with a layer of clear adhesive and press that side against the window.
Because the film 32 is applied to the inner surface 28 of the pane 26, it would be desirable to cover the film 32 with a protective coating or another transparent pane in order to guard against scratches and other damage to the film 32. In alternative embodiments, however, the film 32 may be applied to the outer surface 30 of the pane 26, in which case a protective layer may not be required for those aircraft window designs that employ one or more additional panes between the outer surface 30 and the exterior of the aircraft.
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In order to better attenuate the RF energy, the layer 50 is electrically grounded which is accomplished by use of strip of electrically conductive film (not shown) secured to the window perimeter and the inside of the aircraft skin by conductive adhesive. Alternatively, electrical grounding can be accomplished by overspraying of the window surround with the layer 50 material so as to establish electrical continuity. In yet further alternative embodiments, electrical grounding can be accomplished by other means known in the art.
Because the layer 50 is applied to the inner surface 46 of the pane 44, it would be desirable to cover the layer 50 with a protective coating or another transparent pane in order to guard against scratches and other damage to the layer 50. In alternative embodiments, however, the layer 50 may be applied to the outer surface 48 of the pane 44, in which case a protective layer may not be required for those aircraft window designs that employ one or more additional panes between the outer surface 48 and the exterior of the aircraft.
While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
1. A window comprising;
- a pane; and
- a geometrically patterned grid embedded in the pane, the grid comprising an electrically conductive material and operable to attenuate radio frequency (RF) energy.
2. The window of claim 1 wherein the grid is electrically connected to ground.
3. The window of claim 1 wherein the grid is comprised of generally square openings.
4. The window of claim 1 wherein the grid is comprised of generally triangular openings.
5. The window of claim 1 wherein the grid is comprised of at least one fractal-derived shape.
6. A method of attenuating radio frequency (RF) energy in a window comprising:
- providing a pane;
- forming a geometrically patterned grid of electrically conductive material;
- embedding a geometrically patterned grid in the pane;
- receiving RF energy at the pane; and
- attenuating the received RF energy utilizing the grid.
7. The method of claim 6 further comprising electrically connecting the grid to ground.
8. The method of claim 6 wherein forming a geometrically patterned grid comprises forming the grid of generally square openings.
9. The method of claim 6 wherein forming a geometrically patterned grid comprises forming the grid of generally triangular openings.
10. The method of claim 6 wherein forming a geometrically patterned grid comprises forming of at least one fractal-derived shape.
International Classification: B64C 1/14 (20060101);