Characteristics of voltage holding ratio and residual direct current voltage for polymer-sustained-alignment liquid crystal cells formed from mixed monomers containing biphenyl- and benzilketal-groups

摘要

For improving process efficiency of polymer-sustained-alignment liquid crystal displays (PSA-LCDs), new photo-initiation monomers (PI-monomers), 2-methoxy-2-methacryloyl-oxy-ethoxy-2-phenylacetophenon (2-MMOEP) and 2,2-dimethacryloyl-oxy-ethoxy-2-phenylacetophenon (2,2-DMOEP), were developed and investigated image sticking characteristics. LC cells having PSA layers formed from a monomer 4,4 '-dimethacryloyl-oxy-biphenyl (4,4 '-DMABiph) and each PI-monomer were fabricated, and voltage holding ratio (VHR) and residual direct current voltage (V-rDC) were clarified as the image sticking characteristics. The VHR and theV(rDC)were improved with the LC cells having the PSA layers formed from 4,4 '-DMABiph and 2,2-DMOEP owing to large rate constant of polymerization. In contrast, the VHR and theV(rDC)were deteriorated with the LC cells having the PSA layers formed from 4,4 '-DMABiph and 2-MMOEP. The deterioration of the VHR and theV(rDC)was derived from the increase in the concentration of radical and/or ion generated from 2-MMOEP. The results indicate that the number of polymerizable group in the PI-monomer is important, and plural number of polymerizable group in the PI-monomer leads to high VHR and lowV(rDC).