A new kind of bistable nematic liquid crystal display based on surface properties has been realized.
This black and white device uses simple monostable planar and tilted anchorings and is controlled by short electric pulses. Writing and erasing is achieved by 3us pulses at driving voltage U approximately equal to 27 volts or by 1 ms pulses for U approximately equal to 5 volts. The cell has the usual sandwich geometry: the nematic fills the space between two flat transparent plates and the electric field is perpendicular to the two boundary plates.
The basic idea to obtain this device was to better understand the nematic surface properties and to try to control them by means of an external electric field. The surface switching is obtained by means of the anchoring breaking mechanism.
The proposed research is directed at developing the basis for a new family of passive nematic liquid crystal optical devices characterised by
- fast writing and response time
- true bistability
- easy large multiplexing possibility.
The project is based on the recent discoveries (made in Orsay, France, in collaboration with Italian researchers and protected by patents of CNRS) about the surface bistability of nematic liquid crystals on opportunely coated glass plates. This property has been used to realise new nematic bistable optical pixels in three different cell geometric and with two different switching mechanisms.
The project is devoted
- to master the surface treatment with several techniques
- to synthesise new mesomorphic materials
- to analyse the surface interactions and dynamics
- to test new geometreis for bistable nematic displays
- to check the multiplex ability of the best selected pixel geometry
- to define the best process for a pixel prototype
- to produce a demonstrator to show the effect of the surfaces as a starting step for a further Industrial Research.
Funding SchemeCSC - Cost-sharing contracts
G1 1XH Glasgow