Nobuhiko Ichikawa

Holographic light-control film for liquid crystal displays

We have been developing various holographic optical elements (HOEs) and holograms. In this paper holographic light control films (HLCFs) for use with reflective monochromatic type liquid crystal displays (LCDs) are discussed. The HLCFs are volume type holograms which diffract selected wavelengths of the ambient light to specific angles. Using HLCFs as reflectors in conjunction with LCDs allows the concentration of reflected light to specific viewing areas. Three beneficial characteristics of HLCFs, weak dependence upon incident light angles, good control of diffracted color and excellent environmental stability are described. (1) Weak dependency on incident light angles: Specially designing master holograms and replication conditions allows the production of HLCFs only depend weakly on the angle of the incident light. (2) Control of diffracted color: Varying process conditions allows the creation of HLCFs which diffract specific colors. (3) Stability during and after environmental tests: Using DuPont photopolymers resulted in good stability for both low and high temperatures and high humidity test conditions. In addition, the TEM pictures of the cross sections were shown.