Relationship between surface order and surface azimuthal anchoring strength of nematic liquid crystals

Oka, Shinichiro; Mitsumoto, Takashi; Kimura, Masaaki; Ariga, Tadashi

doi:10.1103/physreve.69.061711

Cited by 26 publications

(26 citation statements)

References 24 publications

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“…Turning to the factors W ϕ 2 and C int separately, there is ample evidence from the literature that W ϕ 2 is not strongly sensitive to rubbing strength. Oka et al [17] observed a sharp increase in W ϕ 2 for very weak rubbing (corresponding to n f approximately onetenth of the smallest nonzero value used in our experiment), above which W ϕ 2 is almost constant with increasing rubbing strength. Likewise, using an atomic force microscope to scribe a polymer alignment layer, Rastegar et al showed that W ϕ 2 is nearly independent of the vertical scribing force for fixed line separation [18].…”

Section: Discussionsupporting

confidence: 44%

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Surface topography and rotational symmetry breaking

et al. 2012

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The surface electroclinic effect, which is a rotation of the molecular director in the substrate plane proportional to an electric field E applied normal to the substrate, requires both a chiral environment and C(2) (or lower) rotational symmetry about E. The two symmetries typically are created in tandem by manipulating the surface topography, a process that conflates their effects. Here we use a pair of rubbed polymer-coated substrates in a twist geometry to obtain our main result, viz., that the strengths of two symmetries, in this case the rub-induced breaking of C(∞) rotational symmetry and chiral symmetry, can be separated and quantified. Experimentally we observe that the strength of the reduced rotational symmetry arising from the rub-induced scratches, which is proportional to the electroclinic response, scales linearly with the induced topographical rms roughness and increases with increasing rubbing strength of the polymer. Our results also suggest that the azimuthal anchoring strength coefficient is relatively insensitive to the strength of the rubbing.

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Section: Discussionsupporting

confidence: 44%

“…The low n f saturation of W ϕ 2 (Ref. [17]) suggests that the polymer's orientational order parameter at the surface saturates for weak rubbing. But Fig.…”

Section: Discussionmentioning

confidence: 99%

Surface topography and rotational symmetry breaking

et al. 2012

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“…In this way, the interfacial layer dominates LC anchoring and, because anchoring is closely related with display defects, also with light leakage and image sticking . To reduce image sticking in in‐plane switching (IPS) LCDs, increasing order parameter at the interface and azimuthal anchoring strength is very effective .…”

Section: Parameters That Define Lc Configurationmentioning

confidence: 99%

Alignment control technology of liquid crystal molecules

Ishihara

Mizusaki

2019

J Soc Info Display

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Liquid crystal displays are now indispensable in everyday life. The display characteristics considerably depend on the configuration of liquid crystal (LC) molecules and interactions between the LC molecules and an alignment film surface. In this paper, we introduce various methods to control parameters that dominate the LC alignment. These parameters include order parameters, the pretilt angle, the director direction, and surface anchoring strength. We also introduce their evaluation methods. In particular, recent alignment film‐free technology is explained in detail. In addition, details of how these parameters are related to the display characteristics, particularly wide viewing angles and fast response characteristics, are described primarily with reference to recent technologies.

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“…The former is a surface-transition-type (high nematic wettability) LC, the latter is a bulk-transition-type (relatively low wettability) LC. 4) Azimuthal anchoring energy was measured by the torque balance method. 5) The deviation angle ÁÈ from the ridge of the gratings indicates the azimuthal anchoring energy A caused by the relief grating.…”

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confidence: 99%

Surface Azimuthal Anchoring Energy between the Grating Surface and Nematic Liquid Crystal Layer Studied by Finite Element Method

Ohta

Tanaka

Kimura

et al. 2004

Jpn. J. Appl. Phys.

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It has been pointed out that Berreman's topological alignment model is applicable to a fairly shallow grating surface, but not for gratings with deep groove profiles. The reason for Berreman's model breakdown was presumed to be the absence of a second derivative in the algebra of elastic theory. In this paper, the saturation tendency of surface azimuthal anchoring energy as a function of the grating height as decribed by numerical simulation on the basis of finite element method (FEM). A good agreement between FEM and experimental results was also demonstrated.

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Relationship between surface order and surface azimuthal anchoring strength of nematic liquid crystals

Cited by 26 publications

References 24 publications

Surface topography and rotational symmetry breaking

Surface topography and rotational symmetry breaking

Alignment control technology of liquid crystal molecules

Surface Azimuthal Anchoring Energy between the Grating Surface and Nematic Liquid Crystal Layer Studied by Finite Element Method

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