This information is supplied courtesy of Hitachi

LCD (LCOS) technology versus DLP

In a conventional (transmissive) LCD panel, the light passing through each element is obstructed by the connections to that pixel element. These control circuits block the light passing through the LCD panel and as resolution is increased soothe aperture ratio is further reduced.

In Hitachi's LCOS panel, light is reflected back through the liquid crystal by the mirrored surface of a silicon substrate containing the control circuits. Without the control circuits between them the liquid crystal elements can be placed very close together producing a smooth, natural image onscreen and yielding an aperture ratio of 92% compared with 40-60% for transmissive panels.

This results in higher contrast ratio and the ability to manufacture more compact panels that achieve similar resolution and brightness. The secret of Hitachi's original LCOS technology is the use of very narrow spacing between the plates allowing the thickness of the liquid crystal to be halved, greatly reducing response time - the thinner the liquid crystal, the faster it can change state in response to control signals. This is particularly important for video with moving content where a slow response time leads to image smearing.