Showing papers on "Homeotropic alignment published in 1977"

Liquid crystal display with dark characters on light background

Abstract: A dichroic liquid crystal display of the parallel-nematic type is caused to have a bright background, indicative of the light-transmissive state, and dark characters, in the unactivated condition, by treatment of the display electrodes to cause boundaries of the dichroic liquid crystal material to be normally homeotropic except in those areas defining a character, in which areas a pattern of silicon oxide or other parallel alignment surfactant is deposited by masking techniques.

Cols and noeuds in a nematic liquid crystal with a homeotropic cylindrical boundary

Abstract: The influence of forces tending to cause flow of the liquid on the motion of noeuds and cols in the director pattern of a nematic liquid crystal in a capillary with homeotropic boundary conditions is observed and qualitatively explained. Diffuse singularities' are explained as Becke lines produced by the distortion of these singular points. The formation of singular points from loops of disclination is observed and discussed, and evidence is produced that the equilibrium configuration of a singular ‘point’ may be a small disclination loop.

The Application of Nematic Liquid Crystals as Anisotropic Solvents inthe Optical Absorption Spectroscopy for the Determination of the Polarization of Electronic Transitions of Organic Molecules and Cu(II) - Complexes

Abstract: Nematic liquid crystals are well suited as anisotropic solvents in the optical absorption spectroscopy. They make it possible to determine the band polarizations of solute molecules by linear dichroism measurements. With homogeneously aligned nematic phases the investigation can be performed by polarized light, with homeotropic layers by natural light. With the nematic phases used (N9, ZLI 612/Merck) a wavelength range down to c. 325 nm can be achieved.

Liquid crystal cell

Abstract: A nematic liquid crystal cell operating in a field effect scattering mode employs a surfactant to provide homogeneous random alignment of the nematic director. Field effect scattering mode operation improves over dynamic scattering mode operation by using an electric field to switch between homeotropic and homogeneous random alignment.

Application of infrared ATR spectroscopy to liquid crystals. I. Surface-induced orientation in thin films of nematic MBBA.

Abstract: Infrared dichroism of nematic liquid N-(p-methoxybenzylidene)-p-butylaniline (MBBA) was measured using a conventional transmission method and an ATR method. In the former, KBr windows were used as substrates. The degree of orientation order of the homogeneous structure, which was achieved by a rubbing procedure, was obtained to be S=0.40. Using the measured dichroic ratios, the angles between the transition moments and the long axis of the molecule were calculated. The calculated values are in satisfactory agreement with the molecular conformation already suggested. In the ATR method, In2O3-coated glass plates were used as substrates. Rubbing of the In2O3 surface gave a uniform homogeneous orientation with an S value of 0.57. An In2O3 surface treated with dimethyldichlorosilane gave a homeotropic texture with an S value of 0.53. The directions of the transition moments relative to the long axis of the molecule closely agreed with those obtained from transmission spectra.

Molecular Alignment of Bubble Domains in Large Pitch Cholesteric Liquid Crystals

Abstract: Based on the naive model, the molecular alignment of the bubble domain in large pitch cholesterics is calculated numerically by using the continuum theory of liquid crystals. It is shown that the bubble domain is surely stable under certain conditions but when the cell thickness is thinner than the critical thickness homeotropic alignment is more favourable. The effects of the electric field on the bubble diameter are also investigated. Obtained results agree well qualitatively with the experimental results.

Liquid crystal element

Abstract: PURPOSE:To realize uniform orientation in a large area of substrate surface relatively easily, stabilize the orientation property of liquid crystal, and possess excellent permanance, durability, and reliability, by treating the substrate surface containing electrodes with specific polynuclear metal complex. CONSTITUTION:Electrode substrates 1, 2, of which one piece at least is transparent, is coated with a solution of Crown compound carboxylic acid polynuclear metal complex, such as those shown in formulae I, II [M is a metal atom; R is a heero- great-cyclic compound (derivative) generally called as Crown; X is an anion; and (n) is 1, 2], and an oriented layer 7 is composed after drying. The substrates 1, 2 are secured in the outer circumferential parts thereof with adhesive 4 by way of a spacer 3, and liquid crystal 6 is charged in from an injection port 5. According to the layer 7, homeotropic orientation H is applied to the nematic liquid crystal, focal conic or orientation H is provided to the cholesteric liquid crystal, and orientation H is applied to the smectic liquid crystal. Also, by griding the surface of layer 7 in a certain direction, homogeneous orientation may be provided to the nematic or other liquid crystal.

Liquid crystal alignment film birefringence compensation

Abstract: Alignment films provided on a supportive substrate in accordance with the Janning technique exhibit birefringence wherein plane polarized light in passing through the alignment film becomes elliptically polarized. Birefringence compensation is provided by depositing a second alignment film on the other side of the supportive substrate in a direction substantially orthogonal to the deposition direction of the first alignment film, the second alignment film having a thickness substantially equal to that of the first alignment film.

Smectic:A phase liq. crystal recording and memory system - modifies molecular arrangement and optical properties by electric writing field

Abstract: Data are represented by modifications of the optical properties of a liq. crystal system. An electrical writing field is used to modify the molecular arrangement in the liq crystal and thus its optical properties. The orientation of the molecules in the initial smectic-A state depends upon the sign of the dielectric anisotropy. The liq. crystal system is illuminated by a readout beam. The electric field then induces faults in the liq. crystal s.t. the beam becomes diffused. The final orientation of the molecules is homeotropic when the electric field exceeds a threshold level. The liq. crystal system may be placed between two crossed polarizers orientated at 45 deg. to the alingment direction of the molecules in the liq. crystal.

Average Orientation in a Three-Dimensional Layer of Nematic Liquid Crystal

Abstract: The average orientation of a nematic liquid crystal is calculated from the Ericksen-Leslie theory for a three-dimensional parallelepiped. When strong magnetic, electric or flow fields are present to determine the orientation, existing results show the effect of side walls on orientation is not great. In the absence of these forces, however, the side walls can influence the average orientation in the sample.e.g. when the homeotropic orientation of a side wall causes an orientation perpendicular to the homeotropic orientation of the top and bottom surfaces. Calculations give the average orientation when only surface effects are considered, i.e. in the absence of magnetic, electric and flow fields, for a homeotropic orientation of the liquid crystal on all surfaces. Results are well approximated by where the overbar denotes a transverse average (in the x and y directions), φ is the angle between the vertical z axis and the director. Lz is the thickness of the layer. and Lx is the length of the side ...