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As a model of polymer-sustained-alignment liquid crystal display (PSA-LCD), the LC cells having the PSA layers (PSA-LC cells) formed by mixed monomers of 2,7-dimethacryloyl-oxy-phenanthrene (2,7-DMAPhen) and 4,4'-dimethacryloyl-oxy-benzophenon (4,4'-DMABenz) were fabricated, and image sticking parameters and long-term stability under LED-backlight exposure were investigated. Residual direct current voltage (VrDC) and difference in pretilt angle (Δtilt) before and after application of alternate current voltage were evaluated as the image sticking parameters. The VrDC was improved with the addition of a small amount of 4,4'-DMABenz because the concentrations of radical and/or ion in the LC layer had decreased significantly. It was shown that with the addition of 3.8 wt% of 4,4'-DMABenz in the mixed monomers, VrDC can be kept low without increasing Δtilt. Voltage holding ratio was maintained high under the LED-backlight exposure for 1,000 h, indicating that the PSA-LC cell shows high long-term stability. Hence we expect that the proposed PSA-LC cell would be useful for high luminance LCDs. [ABSTRACT FROM AUTHOR]

As a model of polymer-sustained-alignment liquid crystal display (PSA-LCD), the LC cells having the polymer layers produced from mixed monomers of 4,4ʹ-dimethacryloyl-oxy-biphenyl (4,4ʹ-DMABiph) and 4,4ʹ-dimethacryloyl-oxy-benzophenone (4,4ʹ-DMABenz) were fabricated and investigated image-sticking phenomenon with evaluations of residual direct current voltage (VrDC) and difference in pretilt angle before and after application of alternate current voltage (∆tilt). A rate constant of the polymerisation became large with an addition of a small amount of 4,4ʹ-DMABenz into 4,4ʹ-DMABiph. The VrDC was effectively improved with the addition of a small amount of 4,4ʹ-DMABenz because the concentrations of radical and ion in the LC layer were decreased due to enlargement for the rate constant of the polymerisation. The Δtilt was small enough only below 14% of 4,4ʹ-DMABenz in the mixed monomers of 4,4ʹ-DMABiph and 4,4ʹ-DMABenz. We confirmed that the PSA-LC cell produced from the mixed monomers of 4,4ʹ-DMABiph and 4,4ʹ-DMABenz with the weight ratio of 4,4ʹ-DMABenz between 9% and 14% was useful for obtaining the small level of image sticking. [ABSTRACT FROM AUTHOR]

As a model of polymer-sustained-alignment liquid crystal display (PSA-LCD), the LC cells having the polymer layers produced from mixed monomers of 4,4ʹ-dimethacryloyl-oxy-biphenyl (4,4ʹ-DMABiph) and 4,4ʹ-dimethacryloyl-oxy-benzilketal (4,4ʹ-DMABzk) were fabricated and investigated image sticking phenomenon with evaluations of residual direct current voltage (VrDC) and difference in pretilt angle before and after application of alternate current voltage (∆tilt). A rate constant of the polymerisation became remarkably large with an addition of a small amount of 4,4ʹ-DMABzk into 4,4ʹ-DMABiph. The VrDC was effectively improved with the addition of a small amount of 4,4ʹ-DMABzk because the concentrations of radicals and/or ions in the LC layer were decreased due to enlargement for the rate constant of the polymerisation. The Δtilt was small enough only below 10% of 4,4ʹ-DMABzk in the mixed monomers of 4,4ʹ-DMABiph and 4,4ʹ-DMABzk. We confirmed that the PSA-LC cell produced from the mixed monomers of 4,4ʹ-DMABiph and 4,4ʹ-DMABzk with the weight ratio of 4,4ʹ-DMABzk between 6% and 10% was useful for obtaining the small level of image sticking. [ABSTRACT FROM AUTHOR]

As a model of polymer-sustained-alignment liquid crystal display (PSA-LCD), the LC cells having the PSA layers formed from mixed monomers of 2,7-dimethacryloyl-oxy-phenanthrene (2,7-DMAPhen) and 4,4′-dimethacryloyl-oxy-benzilketal (4,4′-DMABzk) were fabricated and investigated image sticking phenomenon with evaluations of residual direct current voltage (VrDC) and difference in pretilt angle (Δtilt) before and after application of alternate current voltage. A rate constant of the polymerization became large with an addition of a small amount of 4,4′-DMABzk into 2,7-DMAPhen. The VrDC was effectively improved with the addition of a small amount of 4,4′-DMABzk because the concentrations of radical and/or ion in the LC layer were decreased due to enlargement of the rate constant of the polymerization. The Δtilt was small enough only below 9.1 wt% of 4,4′-DMABzk in the mixed monomers of 2,7-DMAPhen and 4,4′-DMABzk. We confirmed that the PSA-LC cell formed from the mixed monomers of 2,7-DMAPhen and 4,4′-DMABzk with the weight ratio of 4,4′-DMABzk between 3.8 wt% and 9.1 wt% was useful for obtaining the low level of image sticking. [ABSTRACT FROM AUTHOR]

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 (VrDC) were clarified as the image sticking characteristics. The VHR and the VrDC 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 the VrDC were deteriorated with the LC cells having the PSA layers formed from 4,4′-DMABiph and 2-MMOEP. The deterioration of the VHR and the VrDC 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 low VrDC. [ABSTRACT FROM AUTHOR]

As a model of polymer-sustained-alignment liquid crystal display (PSA-LCD), the liquid crystal (LC) cells having the polymer layers produced from monomers of phenanthrene (Phen)-carrying monomers, 2,7-, 3,8-, 1,8- and 3,6-dimethacryloyl-oxy-phenanthrene (DMAPhen), were prepared and investigated image sticking phenomenon with evaluations of residual direct current voltage (VrDC) and difference in pretilt angle before and after application of alternate current voltage (Δtilt). TheVrDCvalues were small for the LC cells with the polymer layers produced from the Phen-carrying monomers used in this study. On the other hand, Δtilt depends on the molecular structure of the Phen-carrying monomer. The Δtilt values became small with increasing the linearity of the monomer structure for the Phen-carrying monomers. The findings would be useful for obtaining the small level of image sticking in the PSA-LCDs produced from the Phen-carrying monomers. [ABSTRACT FROM AUTHOR]

Polymer-sustained-alignment liquid crystal display has high potential for low power consumption, fast response, and low level of image sticking. In this study, we clarified the mechanism for a formation of a polymer layer with polymerization of the monomer 2,6-dimethacryloyl-oxy-naphthalene (2,6-DMANaph) without initiators under UV light exposure. Experimental results revealed that the polymerization of 2,6-DMANaph occurred with the generation of radicals from the monomer as reactive intermediates of a photo-Fries rearrangement. It took about 20 min for 0.5 wt. % of the monomer in the LC to convert to the polymer, indicating that the generation of the radicals derived from the reactive intermediates of the photo-Fries rearrangement is effective for the formation of the polymer layer. Voltage holding ratio of the LC cell having the polymer layer formed from the monomer 2,6-DMANaph was over 99%, which was comparably high value. [ABSTRACT FROM AUTHOR]