Optical and Quantum Electronics 26 (1994) $571-$58I Modelling and characterization of ferroelectric liquid crystal displays J. M. OTON, J. M. S. PENA, J. SABATER Dept. Tecnologfa, Fot6nica, ETSI Telecomunicaci6n, Universidad Pofit~cnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain Received 20 May; revised 8 September; accepted 9 September 1993 Modelling of liquid crystal displays is useful to predict their optical properties and dynamic behaviour. An integrated modelling system for ferroelectric liquid crystal displays has been developed. The system employs data from real FLC materials, polarizers, glasses, backlights, and colour filters, aiming to describe actual devices accurately. Optical transmission dependence on light wavelength and angle of incidence is obtained as a function of the liquid crystal director profile. This profile is in turn derived from energy minimization of bulk and glass surface conditioning contributions. The above static model has been extended to study sample switching in multiplexed displays. Usual slot times in actual displays are quite close to time response of FLC materials, hence no energy-minimized configurations are obtained upon switching. A dynamic model has been formulated to derive the director profile evolution with time, according to the employed driving scheme, and the rotational viscosity of the material. Predicted dynamic and optical results have been compared to experimental measurements on FLC test cells. It has been found that the behaviour of FLC cells depends on a large number of physical and optical parameters. Some of them may be obtained from FLC data sheets, and manufacturing conditions. Other parameters related to director profiles in relaxed states may be experimentally obtained by sample characterization through optical transmission measurements. A few little known parameters (e.g. specific elastic constants) remain; fortunately their influence on cell dynamics is low. 1. Introduction Ferroelectric liquid crystal (FLC) displays have been extensively studied since bistability of surface-stabilized configurations of these materials (SSFLCs) was demonstrated by Clark and Lagerwall [1] in smectic C phases of chiral molecules (SmC*). Being an intrinsic property of SmC* materials, such bistability opened the possibility of manufacturing large area, multi- plexed, fiat panel displays which needed no refreshing nor active elements. Actually FLC displays are the only alternative to active matrix liquid crystal displays for high perfor- mance, non-emissive devices requiring outstanding features such as video rate, large area, grey scale, colour, and high resolution [2]. These expectations, however, have been impaired by a number of practical difficulties concerning FLC materials and manufacturing processes. 0306-8919 9 1994 Chapman & Hall S571