Passive Matrix Addressing of Bistable Displays

Bistable displays neither require the more expensive active matrix addressing, nor are they bound by the rule of Alt and Pleshko limiting the number of addressable lines. The bistable devices discussed are ferroelectric, cholesteric and nematic liquid crystal crystals (LCDs). Bistability is necessarily associated with a hysteresis. The data pulses travelling down the columns generate a parasitic voltage across each pixel of the column. This voltage causes the LC molecules to oscillate around their stable state, causing transient variations of the grey shade, which decreases contrast. The design of the addressing parameters for ferroelectric LCDs (FLCDs) is more complex than for Twisted Nematic displays. FLCDs provide a fast and low energy display with memory. Chiral nematic displays can assume the two stable states, the reflective planar state and the focal conic texture, which is slightly backscattering. The chapter provides an example for passive matrix addressing of a cholesteric display.