Liquid Crystal on Silicon Displays

Reflective liquid crystal displays that are formed on a silicon wafer, which contains the addressing circuits for each pixel, are called Liquid Crystal on Silicon (abbreviated to LCOS) displays. Applications for LCOS are micro-displays, also called virtual displays, and light valves for projectors. As a DRAM (Dynamic Random Access Memory) has a similar configuration, consisting of a transistor and a capacitor as a memory, the addressing circuit is called a DRAM-type circuit. The DRAM-type circuit is associated with analog addressing. Directly underneath each pixel of a micro-display, an Static Random Access Memory (SRAM) cell is located in the Si wafer, and is loaded time sequentially with the bits of a digital word representing the grey shade. A microdisplay consists of a fingernail-sized reflective LCOS as the picture source, and illumination and magnifying optics.