Fabrication technology for flexible ferroelectric liquid crystal display devices using polymer walls and fibers

We report a fabrication technology for plastic-substrate display devices containing monostable ferroelectric liquid crystal (FLC) and molecularly-aligned polymer structures for realizing flexible moving-image displays. In the device fabrication process, polymer walls and fibers (which stabilize the thin plastic film substrates and which monostabilize the FLC alignment to create grayscale capability respectively) are formed sequentially by photopolymerization-induced phase separation using a two-step UV irradiation method. In the first exposure, an FLC/monomer solution that was sandwiched between rubbed polyimide alignment layers was irradiated with UV light through a photomask. Molecularly-aligned polymer walls were formed in the exposed areas when another nematic liquid crystal material (5% or more) was mixed in advance into the solution to maintain the homogeneous alignment of the FLC/monomer molecules during the wall formation. In the second exposure, unreacted monomers that remained in the masked areas were photopolymerized by irradiation with uniform UV light without the use of a photomask, and consequently, molecularly-aligned polymer fibers were formed in the FLC. A4-paper-sized flexible FLC displays were fabricated by a plastic-substrate-based process that uses printing and transfer techniques. Full-color moving images were displayed on the FLC panel (96 x 64 pixels) using a flexible backlight.