Measurements of Lateral Ion Transport in LCD Cells

Abstract

The ions present in liquid crystal devices modulate the applied electric field and lead to deterioration of the expected good optical response. In addition to the flicker and ghost images, a boundary image-retention effect is also possible. It occurs near the edges of a stressed pixel. We have attributed this effect to ions moving in the plane perpendicular to the applied electric field. This hypothesis has been proven using a combination of electrical and optical measurements. The observed optical non-homogeneity and its evolution with stress time were explained using the new model of lateral ion transport. The physical cause of this phenomenon is subject to further study.

The Influence of the Driving Voltage and Ion Concentration on the Lateral Ion Transport in Nematic Liquid Crystal Displays

“…We first measured the effect in STNs and proved that this phenomenon occurs due to ion motion in the plane of the glass plates. 7) Then we explained the mechanism behind it, 8) and finally performed simulations and further measurements to explain the frequency dependence of the lateral ion transport. 9) This paper concludes our research by investigating the other important parameters: the amplitude and dc component of the driving waveform, and the ion concentration in the display.…”

“…6) Recently, we have discovered the lateral ion transport in STN displays in the absence of lateral electric fields. 7) This phenomenon is responsible for the development of dark and bright regions on opposite sides of a stressed pixel (or block of pixels). The change of transmission at the edges of a pixel is called boundary image retention.…”

A new design technique of TFT–LCD display for avionics application

“…In the area of the cut, a very thin layer of UV glue was laid as a mechanical barrier against humidity and other contaminants that can lead to amplify ion's effects [9][10][11][12].…”