Merits and demerits of LCoS projection systems
The merits include:
● IC compatibility: The LCoS electronic substrate is compatible with the standard silicon technology, allowing additional driving circuitry to be integrated into the back-plane design.
● Cost effectiveness for high resolution: LCoS can achieve HD resolution (1920 X 1080) in a 0.711 panel and 1280 X 720 in a 0.511 panel.
● No screen-door effect.
● Smooth picture: The pixel edges in LCoS tend to be smoother and more natural looking compared with the sharp edges of the micromirrors with DLP.
● High contrast.
● High response speed.
Demerits include:
● Long-term reliability.
● Colour break-up is observed in single-panel system as in single-panel DLP systems.
● Complexity.
Other projector technologies
In addition to the projection systems mentioned above, there are several other technologies under development. These include the colour filterless single lens projector illustrated in Figure 19.15.
In this configuration, three dichroic mirrors are stacked in a non-parallel arrangement to split the white light beam into three primary colours beams. Alternatively, RGB angular separation may be achieved by holographic or blazed diffraction grating. The three beams are then projected onto a single LC LV from different incident angles. The LV pixels are divided into three RGB cells. A microlens array is used to direct the beams to their correspon- ding cells. The advantage of eliminating the colour filter is the recovery of
light absorbed by the filter thus making the single-panel projector as bright as a 3-plane projector without the extra expense and size.
Other technologies include the polymer-dispersed LC (PDLC) devices which scatter light but appear transparent when a high voltage is applied, surface-stabilised ferroelectric LCs (SSFLCs) which exhibits two states de- pending upon the polarity of applied voltage and actuated mirror array (AMA) based on piezoelectric angular deflection of individual mirrors within an array and light amplifiers in which low-intensity image is amplified for high-intensity projection.