Ion Transport in IPS Cells

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Ghent University

Ion migration in a liquid crystal (LC) cell can have a significant influence on the electric field and this in turn on the liquid crystal director orientation, even when the ion concentration is low. On application of a voltage, charges migrate towards the electrodes and accumulate at the alignment layers, effectively reducing the applied potential across the cell and therefore reducing the director tilt reached. The relaxation time of the cell can be significantly increased due to the long diffusion time of the ions. In some cases an image from one displayed frame persists to the next; an effect known as image sticking. Although the ion content of LC cells is generally low,
it tends to increase with the device age. A square wave voltage excitation is normally applied to overcome these problems, but as DC offsets remain; the study of this effect is important.

This page last modified 2 June, 2006 by r.james