Adhesive backed displays

#The present invention relates to display applications, and in particular, to displays having an adhesive backing.

#Many applications can benefit from inclusion of a display. For example, sketching apparatuses, telephones, pocketbooks, and battery indicators are only a few applications that could display transient information. To date, widespread incorporation of displays has been hindered because such applications generally require flexible displays that consume very little power.

#Despite much effort directed to developing highly-flexible, reflective display media, there are relatively few examples of displays formed on semi-flexible substrates, and these examples have found only moderate success. For example, plastic-based liquid crystal displays, including twisted nematic (TN), supertwisted nematic (STN), polymer dispersed liquid crystal (PDLC), and bistable cholesteric liquid crystals have been developed. Nevertheless, problems remain with liquid crystal alignment in TN and STN displays, cholesteric displays are sensitive to changes in their cell gap, and local stress can cause changes in the scattering or absorbance of PDLC and cholesteric films. As such, only moderate flexibility can be achieved with these displays.

#The invention is pointed with particularity in the appended claims. The advantages of the invention described above, together with further advantages, may be better understood by referring to the following description taken in conjunction with the accompanying drawings. In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.

#FIG. 1 shows an exploded view of one embodiment of a printed flexible electrophoretic display.

#FIG. 2 shows a block diagram of an indicator prepared according to the present invention.

#According to the present invention, a substrate is provided and an electronic ink is printed onto a first area of the substrate. The present invention takes advantage of the physical properties of an electronic ink which permits a wide range of printing and coating techniques to be used in creating a display. An electronic ink is an optoelectronically active material which comprises at least two phases: an electrophoretic contrast media phase and a coating/binding phase. The electrophoretic phase comprises, in some embodiments, a single species of electrophoretic particles dispersed in a clear or dyed medium, or more than one species of electrophoretic particles having distinct physical and electrical characteristics dispersed in a clear or dyed medium. The coating/binding phase includes, in one embodiment, a polymer matrix that surrounds the electrophoretic phase. In this embodiment, the polymer in the polymeric binder is capable of being dried, crosslinked, or otherwise cured as in traditional inks, and therefore a printing process can be used to deposit the electronic ink onto a substrate. An electronic ink is capable of being printed by several different processes, depending on the mechanical properties of the specific ink employed. For example, the fragility or viscosity of a particular ink may result in a different process selection. A very viscous ink would not be well-suited to deposition by an inkjet printing process, while a fragile ink might not be used in a knife over roll coating process.

#The optical quality of an electronic ink is quite distinct from other electronic display materials. The most notable difference is that the electronic ink provides a high degree of both reflectance and contrast because it is pigment based (as are ordinary printing inks). The light scattered from the electronic ink comes from a very thin layer close to the top of the viewing surface. In this respect it resembles a common, printed image. Thus, electronic ink is easily viewed from a wide range of viewing angles in the same manner as a printed page. Such ink approximates a Lambertian contrast curve more closely than any other electronic display material. Since electronic ink can be printed, it can be included on the same surface with any other printed material. Electronic ink can be made optically stable in all optical states, that is, the ink can be set to a persistent optical state. Fabrication of a display by printing an electronic ink is particularly useful in low power applications because of this stability.

#If desired, the colors of electronically active and non-active inks may closely match and the reflectivities may be similar. Electronic inks can be printed so that no border is noticeable between active and non-active inks. This is referred to as “color matching” or “color masking”. Therefore, a display comprising an electronically active portion may appear as if it is not electronically active when the display is not being addressed and may be activated by addressing the display. Electronic inks are described in more detail in co-pending U.S. patent application Ser. No. 08/935,800, the contents of which are incorporated herein by reference.