Statistical model of greyscale in antiferroelectric liquid crystal cells

Sabater, J.; Otón, J. M.

doi:10.1080/02678299608032821

Cited by 6 publications

(4 citation statements)

References 6 publications

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“…In this context we have already studied the AFLC switching from both modelling [6] and phenomenological approaches [2]. The present work is the logical continuation of the latter phenomenological temporal study of the relax− ation (decay) mechanism in asymmetric AFLC displays driven by video rate biasless waveforms.…”

Section: Introductionmentioning

confidence: 93%

Effect of bias in ferroelectric-antiferroelectric relaxation

Geday

Medialdea

Cerrolaza

et al. 2009

Opto-Electronics Review

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The ferroelectric-antiferroelectric transition in greyscale generation of antiferroelectric liquid crystal displays (AFLC) is a heterogeneous process. The process has been described as the growth of finger-like domains [1]. We have previously studied the ferroelectric-antiferroelectric phase transition, relaxation that follows the data pulse in surface stabilized asymmetric antiferroelectric liquid crystal displays using biasless video frequency waveforms [2]. This relaxation involves an intensity decay of the light transmitted by a pixel and depends on several parameters such as surface stabilization, rotational viscosity of the AFLC, magnitude of the data pulse, and bias voltage.The usual multiplexed driving of AFLC displays leads to long-term stabilisation of the grey levels induced by the data pulses within the selection time. However, depending on the bias level, alternative greyscale mechanisms may be obtained by allowing the grey levels to decay during the frametime. These greyscales may be advantageous in some instances since they improve the dynamic response of the AFLC device and reduce the reset time of the waveform.In this study we extend the previous work to include the effect of bias. We present the measured data, in terms of growth pattern and speed and present an extension of the previously model on order to explain the results.

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Section: Introductionmentioning

confidence: 93%

Effect of bias in ferroelectric-antiferroelectric relaxation

Geday

Medialdea

Cerrolaza

et al. 2009

Opto-Electronics Review

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“…In this respect call this state the continuous director rotation state the polar interaction with the alignment layers plays a (CDR) because it gives rise to the thresholdless V-shaped crucial role, and this was not included by Sabater and characteristics. If the liquid crystal does not remain Oton [6,7]. Fornier et al [8] used a somewhat less in the SU-state but switches to the normal alternating general model but did brie y study the in uence of polar state (NA) with both polarizations perpendicular to the interaction.…”

Section: Introductionmentioning

confidence: 99%

“…Nakagawa [4] and De Meyere and Dahl [5] the liquid crystal in the ferroelectric up-state (FU) and have studied the shape of the chevron structure and tried then lets V gradually decrease, one rst goes over to to develop the most general energy expression. Sabater the SU-state, with the polarization in two successive and Oton [6,7] also used a very general expression and layers symmetrical with respect to the eld direction. If include a chevron structure, bending and motion of the one succeeds in remaining in this state until V 5 0, an chevron tip, dielectric anisotropy, etc.…”

Section: Introductionmentioning

confidence: 99%

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Analytical approach to V-shaped characteristics in antiferroelectric liquid crystal displays

Pauwels¹

2002

Liquid Crystals

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Not only in ferroelectric liquid crystal displays (LCDs), but also in antiferroelectric LCDs, grey levels are possible by actively addressing the 'continuous director rotation mode'. For ferroelectric LCDs this was shown qualitatively and quantitatively in previous articles. In this article it is shown that an exact analytical approach is also possible for antiferroelectric LCDs. In two consecutive layers the director orientations are symmetric, and at zero voltage they are in a splayed state. The conditions on alignment layer thickness and interaction coeYcients are related to those of ferroelectric liquid crystal but are easier to ful ll. Introductionuniform Q-theory, but that an exact analytical solution For antiferroelectric liquid crystals there has been is possible, at least in the bookshelf geometry, and if one discussion as to whether thresholdless V-shaped characneglects dielectric anisotropy. This is not always justi ed teristics are possible [1]. In this discussion an approxibut we think its in uence is negligible at the small mate theory, the so-called uniform Q-theory, plays an voltages where V-shape characteristics take place. important role [2], in which the orientation of the layer The derivation of the equations of motion and of the polarization is considered to be independent of the depth stationary states always starts from an energy expression. within the liquid crystal cell. This theory often gives a Two approaches are used in the literature. Either one qualitative insight into what is happening. The so-called solves the problem with a computer program without symmetrical up-state (SU) plays an important role in avoiding complexity, or alternatively, one tries to nd explaining V-shaped characteristic s [3]. If one has applied analytical solutions and so seeks to avoid non-essential a suYciently strong positive voltage, and thus has set complexity. Nakagawa [4] and De Meyere and Dahl [5] the liquid crystal in the ferroelectric up-state (FU) and have studied the shape of the chevron structure and tried then lets V gradually decrease, one rst goes over to to develop the most general energy expression. Sabater the SU-state, with the polarization in two successive and Oton [6, 7] also used a very general expression and layers symmetrical with respect to the eld direction. If include a chevron structure, bending and motion of the one succeeds in remaining in this state until V 5 0, an chevron tip, dielectric anisotropy, etc. The controversy alternating state (or antiferroelectric state) results, with over V-shaped switching in ferroelectrics and antiferroboth polarizations parallel to the electrodes. We shall electrics was not known at that time. In this respect call this state the continuous director rotation state the polar interaction with the alignment layers plays a (CDR) because it gives rise to the thresholdless V-shaped crucial role, and this was not included by Sabater and characteristics. If the liquid crystal does not remain Oton [6,7]. Fornier et al.[8] used a somewhat less in the SU-s...

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Antiferroelectric gels

Strauß¹,

Kitzerow

1998

Ber Bunsenges Phys Chem

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We have investigated the electro‐optic properties of a gel consisting of an antiferroelectric liquid crystalline (AFLC) mixture and an anisotropic polymer network, formed by photopolymerization of a mesogenic monomer. Like the pure AFLC mixture, the gel exhibits the well‐known tristable electro‐optical switching but with a decreased slope of the electro‐optic response curve, thus making gray‐scales available. In addition, the spontaneous polarization and the switching angle are reduced by the polymer network, whereas the switching times are independent of the polymer concentration. Applying a simple model, we found that the polymer network primarily changes the anchoring conditions of the liquid crystal.

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Statistical model of greyscale in antiferroelectric liquid crystal cells

Cited by 6 publications

References 6 publications

Effect of bias in ferroelectric-antiferroelectric relaxation

Effect of bias in ferroelectric-antiferroelectric relaxation

Analytical approach to V-shaped characteristics in antiferroelectric liquid crystal displays

Antiferroelectric gels

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