Application of FLC/AFLC materials to active-matrix devices

Takatoh, Kohki; Yamaguchi, Hideyo; Hasegawa, Ray; Saishu, Tatsuo; Fukushima, Rieko

doi:10.1002/1099-1581(200008/12)11:8/12<413::aid-pat42>3.0.co;2-o

Cited by 7 publications

(3 citation statements)

References 38 publications

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“…There has recently been much effort devoted to elucidating the structure and polar properties of ferroelectric (FLC) and antiferroelectric (AFLC) phases assembled by chiral smectogens in case of a high enantiomeric excess . The interest in these mesophases stems from their polar properties connected to spontaneous or field induced broken symmetries 1 that can provide a high impact in technological applications, in particular in the LCD manufacturing . Continuous experimental work and several theoretical models have been put forward in attempting to explain the role of chirality, the microscopic nature of molecular organization, and molecular reasons for the phase transitions and synclinic to anticlinic layer arrangements.…”

Section: Introductionmentioning

confidence: 99%

¹²⁹Xe Nuclear Shielding and Diffusion in the A and C* Phases of a Chiral Smectogen

et al. 2004

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The 129Xe NMR shielding and diffusion of xenon dissolved in the chiral liquid-crystal 1-methylheptyl 4‘-(4-n-decyloxybenzoyloxy)biphenyl-4-carboxylate (10B1M7) were studied over the temperature range covering the isotropic (I), smectic A (SmA), and ferroelectric, ferrielectric, and antiferroelectric smectic C*(SmC*) phases. The 129Xe shielding reveals clearly the I−SmA and SmA−SmC*(ferroelectric) phase transitions. The SmC* sub-phase transitions can also be detected by smaller but distinguishable shifts of the shielding accompanied by line width changes. A theoretical model developed earlier is applied to the shielding data, confirming a negative anisotropic contribution to the shielding as the SmA phase forms and allowing the evaluation of the tilt angle in the SmC*. Diffusion experiments were mostly performed in the direction parallel to the layer normal, i.e., along the external magnetic field, D ∥, in the smectic phases but a few experiments were carried out in the in-plane direction, i.e., perpendicular to the external magnetic field, D ⊥, as well. These experiments indicate large anisotropy, D ⊥/D ∥, of the 129Xe diffusion tensor that increases as the temperature decreases. Application of the Arrhenius equation to the temperature-dependence of D ∥ reveals different activation energies for each studied phase. This can be correlated to changes in the smectic layer structure that occur between the different smectic phases.

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Section: Introductionmentioning

confidence: 99%

¹²⁹Xe Nuclear Shielding and Diffusion in the A and C* Phases of a Chiral Smectogen

et al. 2004

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“…Since the response speed of a ferroelectric liquid crystal is much faster than that of the TN mode, various TFT-LCDs using FLC materials have been developed. 1) Recently, several groups have developed half-V FLCDs, ferroelectric liquid crystal displays with a half-V-shaped switching property. [2][3][4][5] The half-V FLC mode is a promising candidate for a fast-response TFT-LCD because the half-V FLC has small spontaneous polarization (P s ) and enables the display of analog gray scale.…”

Section: Introductionmentioning

confidence: 99%

Effect of Non-DC Voltage Applied during N^–SmC^ Phase Transition on Alignment of Half-V-Shaped Switching Ferroelectric Liquid Crystal

Hotta

Hasegawa

Takatoh

2004

Jpn. J. Appl. Phys.

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In a half-V-shaped switching ferroelectric liquid crystal (half-V FLC), a liquid crystal material with N*–SmC* phase transition is used. When the material is cooled from N* phase to SmC* phase without an applied electric field, two types of domain with spontaneous polarization (Ps) in the upward or downward direction to the substrate plane are formed. In the conventional half-V FLC, a DC voltage is applied to the liquid crystal during the phase transition to form either type of domain selectively. Is the DC voltage application indispensable for selecting one domain? To clarify this point and to reduce the expected residual charge due to the application of the DC voltage, various waveforms of non-DC voltage were studied. We achieved the formation of one type of domain by applying an asymmetric rectangular waveform adjusted to cancel the effective DC component, and the generation of residual charge was avoided. The obtained half-V FLC alignment showed desirable black appearance in the crossed polarizers.

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“…The TFT-LCDs using the TLAF materials were fabricated and provided full-color moving images with wide viewing angle. [9][10][11][12][13][14] In the case that liquid crystals with large spontaneous polarization such as TLAF are driven by active matrices and the response of the liquid-crystal molecules cannot be accomplished within a charging (gate-on) time, conventional ac driving can provide only low contrast ratio. 3,9,15 That is because the holding voltage declines sharply due to the growth of a depolarization field.…”

Section: Introductionmentioning

confidence: 99%

A 15‐in. XGA thresholdless antiferroelectric LCD addressed by TFTs and using the quasi‐dc driving method

Hasegawa¹,

Fujiwara²,

Nagata³

et al. 2001

J Soc Info Display

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Abstract— A 15‐in. TFT‐LCD with XGA resolution using thresholdless antiferroelectric liquid crystal (TLAF) has been developed. TLAF materials show V‐shaped switching and enable display of analog gray scale, wide viewing angle, and fast response. However, in the case that high‐resolution TFT‐LCDs using materials with large spontaneous polarization such as TLAF were driven by the conventional method, alternating current (ac) driving, the obtained contrast ratio was limited because of a sharp decline of holding voltage due to the growth of a depolarization field. In order to enhance the contrast ratio, a novel driving method referred to as quasi‐dc driving was proposed. In the quasi‐dc driving, the polarity of the applied voltage to liquid crystals inverts at certain intervals of several seconds. Moreover, the applied voltage and the charging time at the time of polarity inversion are increased more than the intended signals. By this method, the 15‐in. TFT‐LCD using TLAF with high contrast ratio (more than 100:1) and wide viewing angle was realized.

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Application of FLC/AFLC materials to active-matrix devices

Cited by 7 publications

References 38 publications

¹²⁹Xe Nuclear Shielding and Diffusion in the A and C* Phases of a Chiral Smectogen

¹²⁹Xe Nuclear Shielding and Diffusion in the A and C* Phases of a Chiral Smectogen

Effect of Non-DC Voltage Applied during N^–SmC^ Phase Transition on Alignment of Half-V-Shaped Switching Ferroelectric Liquid Crystal

A 15‐in. XGA thresholdless antiferroelectric LCD addressed by TFTs and using the quasi‐dc driving method

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Application of FLC/AFLC materials to active-matrix devices

Cited by 7 publications

References 38 publications

129Xe Nuclear Shielding and Diffusion in the A and C* Phases of a Chiral Smectogen

129Xe Nuclear Shielding and Diffusion in the A and C* Phases of a Chiral Smectogen

Effect of Non-DC Voltage Applied during N*–SmC* Phase Transition on Alignment of Half-V-Shaped Switching Ferroelectric Liquid Crystal

A 15‐in. XGA thresholdless antiferroelectric LCD addressed by TFTs and using the quasi‐dc driving method

Contact Info

Product

Resources

About

¹²⁹Xe Nuclear Shielding and Diffusion in the A and C* Phases of a Chiral Smectogen

¹²⁹Xe Nuclear Shielding and Diffusion in the A and C* Phases of a Chiral Smectogen

Effect of Non-DC Voltage Applied during N^–SmC^ Phase Transition on Alignment of Half-V-Shaped Switching Ferroelectric Liquid Crystal