Method of patterning conductive films

#The present invention relates to electrically conductive film used to coat electroluminescent displays.

#Electroluminescent lamps comprising a transparent conductive base are known in the art. In general, a thin polyester film with an indium-tin oxide (ITO) coating has most often been used for this purpose. These ITO films are manufactured by vacuum sputtering techniques. Screen printing the conductive paste is another method of manufacturing the films.

#More recently, poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate), sometimes abbreviated PEDT/PPS or PEDOT (manufactured and sold under the trade name Orgacon® by AGFA Gevaert) has been found to be a desirable material for use as a transparent conductive base for electroluminescent lamps. Unlike ITO film, which is easily damaged because the inorganic material is very brittle, the PEDOT polymer transparent conductive coating on a polyester film can be stretched, folded and can tolerate surface damaging before the surface conductivity is affected. For these reasons, PEDOT film is better than ITO in less delicate manufacturing processes such as industrial screen-printing.

#FIG. 1 is a photograph of a square of 125 μm PET covered by a film of PEDOT, inkjet printed with various forms in black ink.

#FIG. 2 is a photograph of a square of 125 μm PET covered by a film of PEDOT, inkjet printed with various forms in magenta ink.

#FIG. 3 is a photograph of a square of 125 μm PET covered by a film of PEDOT, inkjet printed with various forms in black ink.

#The invention relates to polymer films that are capable of conducting electricity. The invention more specifically relates to a method of deactivating, i.e., making non-conductive, specific portions of these polymer films by printing certain selected inks in a pattern on the surface of the film. This patterning can be used, for example, to isolate defined areas on a thick-film electroluminescent display. By this method, digitally printed images can be displayed as either static or moving images across the electroluminescent display.

#The conductive polymer films used in the present invention can be made with various materials including triarylamine derivatives, polythiophenes such as poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) and polyaniline derivatives. The most preferred is poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate), sometimes abbreviated PEDT/PPS or PEDOT (manufactured and sold under the trade name Orgacon® by AGFA Gevaert).

#It has been found that PEDOT film can be segmented into individually-addressable areas by printing certain HP inks onto the PEDOT surface. Where the ink contacts PEDOT, the electrical conductivity is sharply reduced. If the pattern is printed on several different areas of the PEDOT surface, the voltage can be switched on and off between the different areas to randomly flash words or images. If the pattern is such that the segregated areas are arranged to be contiguous, a serial controller which switches the EL voltage can illuminate images placed over the patterned areas and give the illusion of motion. Such moving images can be used in commercial signage, advertising, or simply as novelty desk or home items.