Wide Pretilt Angle Control of Liquid Crystal Display Device by Ion Beam Exposure on the Vertical Aligning Layer

Abstract

The pretilt angle of nematic liquid crystals on an alignment layer can be controlled from 2 to 89° by ion beam treatment of the alignment layer. Ion beam is used to partially destruct the vertical functional molecules of the vertical alignment materials. The ion beam-treated surface does not show any morphological difference from non-treated surface. The pretilt angles are generated by the remaining portion of the functional molecules in the material. The remaining portion of the molecules is dependent on the amount of ion beam exposure. We also apply this method to no-bend-bias-voltage optically compensated birefringence (OCB) mode with a pretilt angle of 55°. The OCB cell made by our method is a good candidate for high quality OCB mode because of the merits of uniformity of ion beam alignment and low power consumption of no-bend-bias-voltage.

Nanostructured alignment layer for liquid crystals

“…The range of pretilt angles obtained using this method is not as large as those methods investigated before . The smallest value of VA polyimide area coverage is 50% unless a different grating mask is used.…”

“…Two methods have been proposed and demonstrated in the past to fabricate such inhomogeneous alignment surfaces reliably. In the first method, the inhomogeneity is obtained by differential precipitation of the VA and PA polyimide from a common solution or by ion beam irradiation . The preferred direction in the x–y plane can be obtained either by mechanical rubbing or by photoalignment.…”

“…The present proposed technique is based on the observation that a VA polyimide can be turned into PA by exposing the surface to an oxygen (O 2 ) plasma or by deep ultraviolet (DUV) irradiation. It is because that a VA polyimide usually consists of a PA polyimide with the addition of a long alkyl side chain . If the side chain is destroyed without destroying the main chain, then the VA polyimide becomes a PA polyimide.…”

On liquid crystal diffractive optical elements utilizing inhomogeneous alignment

“…Another advantage is the fact that in practice it is easier to realize a pre-tilt angle variation in a wide range [39][40][41] than an anchoring energy variation.…”

Dopant effects of photoreactive ZnO nanoparticles on fast response LC materials in optical compensated bend (OCB) mode liquid crystal displays

“…Moreover, nano-sized dopant materials, including nanoparticles (Kobayashi et al, 2004;Kobayashi et al, 2002;Miranda, 2006;Boilot et al, 2007;Kobayashi et al, 2007) and nanotube dopants, (Huang et al, 2006) have also been used to enhance the electro-optical properties of various LCDs. High quality (fast response time and lower driving voltage) properties in OCB cells have also been encouraged by the formation of a pixel-isolating polymer wall and by pre-tilt angle behavior in Downloaded by [Selcuk Universitesi] at 03:47 27 December 2014 vertical alignment layer by ion beam exposure (Kim et al, 2008;Kim et al, 2007). However, there have been few examples of the applications and effects of nanoparticles with photoreactive groups on the improvement of the threshold voltage and the response time in OCB mode displays.…”