Liquid Crystal Cell Gap Research Articles

Investigation of the Electro-Optical Dynamics of a Polymer Dispersed Liquid Crystal Based on a Bisphenol A Diglycidyl Ether

A polymer-dispersed liquid crystal based on a biphenol A diglycidyl ether (E-44) and 4-pentyl-4′-cyanobiphenyl was prepared by a method of polymerized-induced phase separation. Electro-optical transmissions of the biphenol-A epoxy resin dispersed liquid crystal were measured as a function of applied alternating voltage over a range of 0–90 V for a liquid crystal cell gap of about 20 μm. Influences of heat treating time and content of firming agent on the electro-optical transmissions of the biphenol A diglycidyl ether dispersed liquid crystal were discussed.

Measuring Cell Gap of Liquid Crystal Displays by Scanning White-Light Tandem Interferometry

In this study, we present a scanning white-light tandem interferometric method for determining the cell gap of liquid crystal displays (LCDs). Compared with conventional methods, the proposed method is simple and applicable to most LC cells. Furthermore, the approximate gap value of a tested LC cell is not required before a measurement is made. The LC cell is placed behind a scanning Michelson interferometer containing a white-light source. The interferometric signal from the scanning interferometer and that from the LC cell are recorded simultaneously as a function of the arm-length difference of the scanning interferometer. The cell gap is directly determined from the separation of the two side white-light fringe packets in the subtraction curve of the two recorded interferometric patterns. The method was validated by measuring four different types of LC cell.

Anchoring energy and cell gap effects on liquid crystal response time

The anchoring energy and cell gap effects on liquid crystal response time (τ0) is analyzed theoretically and validated experimentally. Analytical expressions are derived using two different approaches: effective cell gap and surface dynamic equation methods. Consistent results are deduced from these two approaches. A simplified equation τ0∼dx also fits the experimental data well, where d is the liquid crystal cell gap and x is the exponent. Under two extreme (strong and weak) anchoring limits, the exponent x approaches 2 and 1, respectively. This information is helpful for optimizing liquid crystal devices for display applications.