Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1999-10-13
2002-01-15
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S195100, C428S212000, C428S213000, C428S690000, C428S913000
Reexamination Certificate
active
06338892
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to composite structures useful in backlit displays, and in particular in outdoor, weather resistant backlit displays.
2. Description of the Related Art
Backlit displays have been used in commercial settings and are routinely used for promotional purposes in retail settings. The typical backlighted display device projects light from an enclosed light source out through a graphic display media towards the viewer, thereby enhancing the visual effect (especially in low light situations) during evening hours.
Backlit displays have not achieved widespread utilization in outdoor and self-contained display devices despite the obvious market depth as demonstrated by the importance of image communication available through billboard advertising and the like. The popularity of conventional billboard advertising employing external light and weather proof materials indicates a cause for low interest in outdoor backlit display systems. Conventional backlit display systems employ cumbersome lighting systems which necessitate large equipment which is not weather proof and therefore can only be utilized in large indoor spaces such as airport halls. U.S. Pat. No. 5,943,801 discusses such backlit displays.
There remains a need for backlit displays which can withstand outdoor weather conditions. In general, backlit displays having more simplified light emitting systems are particularly desirable.
SUMMARY AND OBJECTS OF THE INVENTION
In a first aspect, the present invention provides a composite structure comprising an image receiving layer and a light emitting layer. The light emitting layer comprises a phosphorescent or fluorescent material capable of illuminating an image deposited on the image receiving layer. The phosphorescent or fluorescent material is capable of storing energy from an external source and releasing the stored energy in the form of light capable of illuminating the image. The external source is preferably natural or artificial light to be captured and stored by the phosphorescent or fluorescent material.
Preferably, the composite structure of the invention also comprises a support layer having opposite first and second faces. The image receiving layer is disposed on the first face and the light emitting layer is disposed on the second face. The support layer is preferably transparent.
The composite structures of the invention include structures formed by light emitting layers and image receiving layers which are weather resistant, which allows outdoor image illumination under wet weather conditions. The composite structures according to the invention preferably have a thickness of from about 100 &mgr;M to about 1000 &mgr;M.
In another aspect, the invention provides a method of illuminating an image comprising forming a composite structure comprising an image receiving layer having an image thereon and a light emitting layer comprising a phosphorescent or fluorescent material. The method includes the steps of storing energy in the phosphorescent or fluorescent material and illuminating the image by releasing the stored energy in the form of light emitted by the phosphorescent or fluorescent material.
In yet another aspect, the invention provides a method of forming a self-illuminating backlit display comprising disposing an image receiving layer having an image thereon on a first face of a support layer and forming a light emitting layer on a second face of the support layer. The light emitting layer comprises a phosphorescent or fluorescent material capable of illuminating the image.
In still another aspect, the invention provides a composite structure comprising an image receiving layer having an image disposed thereon, a transparent first conductive layer providing a first electrode, a second conductive layer providing a second electrode and a light emitting layer disposed between the first and second electrodes. The light emitting layer is capable of emitting light when an electrical voltage is applied across the first and second electrodes. The electrical voltage is formed by connecting the first and second electrodes to a voltage source.
In still another aspect, the invention provides a method of illuminating an image comprising forming a composite structure comprised of an image receiving layer having an image thereon; supplying an electrical current to the composite structure; and illuminating the image by converting at least part of the electrical current into light emitted by a light emitting layer of the composite structure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention relates to composite structures useful in backlit displays, and particularly in outdoor weather resistant backlit displays. The composite structures of the invention provide significantly simplified and therefore highly practical backlit displays.
Compared to conventional backlit displays, the present invention provides composition structures which form backlit displays having greater flexibility, efficiency in space and energy use as well as high durability. These advantages are provided by the combination of a (front) image receiving layer having an image thereon and a backside layer which emits light that illuminates the image on the image receiving layer. The backside of the structure contains a layer or layers that are capable of providing a source of light such that the image layer will be illuminated to an acceptable level. This backside can be composed of fluorescent, phosphorescent or electroluminescent materials.
In one embodiment, the invention provides an imageable backlit composite structure having a front surface or image receiving layer that can be imaged by ink jet imaging, electrographic imaging or any other direct or transfer imaging technology. Preferably, the imaged layer is water resistant such that the backlit composite structure can be employed in outdoor displays while minimizing the detrimental effects of weather conditions to which the display may be subjected.
The image receiving layer can be an ink jet imageable layer or a surface that is designed to accept transfer imaging. Transfer imaging technologies such as ink jet image transfer, electrographic image transfer and other techniques known in the art can be easily adapted for generating an image on the image receiving layer of the invention.
An example of image receiving layers suitable for forming the composite structures of the invention are described in U.S. Pat. No. 5,853,899, the contents of which are incorporated herein by reference in their entirety. Such layers generally include a substrate having an ink receiving layer provided thereon. The preferred substrates are transparent. One preferred ink receiving layer is comprised of a blend of ethylene vinyl acetate copolymer and hydrolyzed polyvinyl alcohol. Preferably, the ink receiving layer contains a solid particulate such as silica or calcium silicate.
The image receiving layer is preferably imaged by color ink jet printing. The ink is allowed to dry prior to utilization of the imaged layer in outdoor backlit panel display. Imaging an image receiving layer for the composite structures of the invention is advantageously performed through an ink jet printing process described in U.S. Pat. No. 5,837,375, the contents of which are incorporated herein by reference in their entirety. Optionally, the image receiving layer is supported by a transparent or semi-transparent film or paper substrate as is known in the industry.
The image receiving layer whether imaged or not yet imaged is combined with a self-contained light emitting layer to form a composite structure according to the invention. By self-contained light emitting layer it is intended a light emitting layer capable of releasing internal energy, for example energy stored within the light emitting layer by exposure to an external source of light or other form of energy, sufficient to illuminate an image without the need for another source of light or other form of energy. The emitted light or afterglow
Himmelwright Richard S.
McCue John P.
Burns Doane Swecker & Mathis L.L.P.
Hess Bruce H.
Rexam Graphics
Shewareged B.
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