The present invention is directed to methods for improving the performance
of an electrophoretic display by modifying the display cell surface. More
specifically, 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. 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 imageincreasing 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.
