Coating processes – Electrical product produced – Fluorescent or phosphorescent base coating
Reexamination Certificate
1998-10-15
2001-08-07
Yamnitzky, Marie (Department: 1774)
Coating processes
Electrical product produced
Fluorescent or phosphorescent base coating
C156S067000, C156S182000, C156S277000
Reexamination Certificate
active
06270834
ABSTRACT:
Reference is further hereby made to commonly assigned and U.S. patent application ELECTROLUMINESCENT SYSTEM IN MONOLITHIC STRUCTURE, Ser. No. 08/656,435, filed May 30, 1996, now U.S. Pat. No. 5,856,029, the disclosure of which application is incorporated herein by reference.
TECHNICAL FIELD OF THE INVENTION
This application relates generally to electroluminescent lamps and more particularly to a self-contained electroluminescent system provided in an elastomeric structure that may, in transfer form, be affixed efficiently and cost-effectively to a wide variety of substrates having various three-dimensional shapes, or alternatively may be installed as a self-contained membrane-like component in other products.
BACKGROUND OF THE INVENTION
An embodiment of the invention taught by the above-referenced U.S. patent application ELECTROLUMINESCENT SYSTEM IN MONOLITHIC STRUCTURE (the “Previous Invention”) is directed to an electroluminescent (“EL”) system having a unitary carrier whose layers form a monolithic structure. A preferred unitary carrier in this system is a vinyl resin. One of the advantages of this monolithic electroluminescent system is that the layers thereof may be printed down as inks in a screen printing process onto a wide variety of substrates.
It is also known in the art that elastomeric structures have unique and useful properties. Behaving much like sturdy membranes, the malleability and ductility of elastomeric structures enable applications that would otherwise be unavailable to more rigid or plastic components.
There are many potentially advantageous applications of an elastomeric electroluminescent (“EL”) lamp. For example, highly pliable and resilient backlit keyboard facia would be enabled in cellular telephones or other personal communications devices.
Alternatively, elastomeric EL lamps could be constructed in transfer form and then affixed to fibrous substrates, such as fabric. Experimentation has shown that screen printing down EL systems in accordance with the Previous Invention on substrates such as fabric often requires pre-preparation of the substrate for best results. First, the fabric may not always be optimally chemically compatible with the first layer of the EL system. Second, fabric fibers have been found to tend to “stand up” and interfere with an even and uniform print down of the EL system. As a result, although the Previous Invention has been found to be fully functional on such fabrics, the quality of electroluminescence can suffer. It has therefore been found advantageous to preprint a “platform layer” of the unitary carrier (with no EL-active ingredients) onto fabric and similar substrates to inhibit these factors. The EL system is then printed down onto the platform layer in accordance with the Previous Invention.
Although providing this platform layer tends to enhance the performance of the EL lamp, it will be understood to be an additional manufacturing step with attendant time, material and manufacturing process costs.
Moreover, further experimentation with printing down the EL system according to the Previous Invention has also shown that printing works best when the area to receive the printing is flattened out into a plane. For fabric printing, for example, this “flattening” is easily accomplished with garments such as t-shirts, but is not so easy with other garments, such as jackets or baseball caps, for which a “flattening” step may damage or detract from the final appearance of the garment.
There is therefore a general need in the art for elastomeric EL lamps. Such elastomeric lamps would be advantageous as components in products requiring flexible backlighting. Alternatively, in transfer form, such elastomeric lamps could enable improved application of the EL system of the Previous Invention to fibrous substrates, including fabrics, without incurring the additional cost and manufacturing step of pre-preparing the substrate to receive the EL system. Elastomeric EL lamps could also facilitate application of the EL system of the Previous Invention less traumatically to substrates with three-dimensional shapes.
SUMMARY OF THE INVENTION
The present invention is directed to an EL lamp manufactured generally in accordance with the Previous Invention, but as a discrete elastomeric structure. This structure may, if desired, be subsequently affixed to a substrate so as to adopt the utility of a “transfer”. Alternatively, the elastomeric structure may be used as a discrete, self-contained electroluminescent component in applications such as keyboard facia, where a thin, membrane-like EL lamp would be highly advantageous.
In accordance with the present invention, elastomeric EL lamps are manufactured entirely by using screen printing or other printing techniques. Screen printing costs and logistics under the present invention are therefore generally no more complex or involved than if the EL lamp is screen printed directly onto the substrate in accordance with the Previous Invention. Various advantages are gained, however, by constructing the lamp as an elastomeric structure. If the elastomeric structure is to be affixed to a substrate in the form of a transfer, the need to preprepare a fabric or other substrate with a platform layer is obviated. Further, elastomeric EL lamps in the form of transfers according to the present invention are extremely malleable and flexible, enabling subsequent affixation thereof to virtually any three-dimensionally shaped substrate without having to “flatten” an area to receive the printing process. Alternatively, if the elastomeric structure is to be used as a self-contained component, it may be mass-produced and then installed in a product potentially as easily as a gasket or other thin, membrane-like component.
In summary, an EL lamp in an elastomeric structure according to the present invention begins with printing a first envelope layer onto commercially available heavy-grade transfer release paper. Subsequent first envelope layers may be printed down to achieve a desired monolithic first envelope layer thickness. Further, one or more of the layers may be dyed and/or printed in a pattern so that the first layer of the envelope will, in natural light, have a predetermined appearance (such as a logo or keyboard facia layout).
The material of the first layer of the envelope is advantageously (although not required to be) a clear or semi-clear polyurethane. Experimentation has shown that this material has excellent elastomeric properties. Further, this material has been proven to be chemically stable with just about all the materials likely to be encountered in an EL lamp application, including the transfer release paper, the layers of an EL system, the adhesives by which a transfer may be affixed to the substrate, and with most substrates themselves, including fibrous substrates. Polyurethane also is an extremely flexible and malleable material, enabling manufacture of an elastomeric EL lamp that may be adapted or “wrapped” to be easily and nontraumatically receivable on just about any three-dimensionally shaped substrate.
Once the first layer of the envelope has been printed onto the transfer release paper, an EL system, advantageously (although not required to be) in accordance with the Previous Invention, is printed down onto the first envelope layer. The EL system is undersized on the first envelope layer in order to leave a first envelope border around the outside. A second envelope layer is then printed down on top of the EL system, combining around the edges with the first envelope border to seal the EL system within the envelope. Appropriate windows in the envelope are made, or left, to enable electrical contacts to be introduced into the EL system. Again, the second envelope layer is a polyurethane, advantageously printed in several intermediate layers to achieve a desired thickness. In achieving a desired thickness of polyurethane envelope, the design advantageously ensures that the EL lamp within the envelope is electrically isolated from the outside, and that the envelope is watertight.
When
E.L. Specialists, Inc.
Vinson & Elkins L.L.P.
Yamnitzky Marie
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