Methods of surface modification for improving electrophoretic display performance

Abstract

The present invention is directed to methods for improving the performance of an electrophoretic display by modifying the display cell surface. More specifically, when the display cells are prepared by the microcup technology utilizing the embossing process, the methods are directed to modification of the microcup surface after the microcups are released from the mold. The microcups which have undergone any of the treatment methods of the invention show significant improvement in their surface properties, such as chemical functionality, surface roughness, surface tension, morphology, surface charge, surface reflectivity, surface conductivity and optical properties, particularly optical density in the visible light region. As a result, an electrophoretic display formed from the treated microcups has many advantages. For example, the display shows a higher contrast ratio, lower electro-optic response time, lower driving voltage, longer shelf life, higher image bistability and higher threshold voltage. In addition, it exhibits an improved image quality by reducing undesirable scum formation or irreversible particle deposition on the microcup surface. The surface modification also considerably improves the coating and/or adhesion quality in the filling and sealing steps. All of these improvements may be achieved without any compromise in mold release.

Dependencies are inferred from the claim text.