Liquid crystal on silicon

LCoS is the abbreviation of Liquid Crystal on Silicon (German, liquid crystals [ a ] silicon [ substrate ] ') and refers to a technique for display devices similar to a Liquid Crystal Display ( LCD). In contrast to this, it can, however, not by the light, but reflects it.

Construction

LCoS displays are usually very small, the diagonals of 18 mm ( 0.7 inches) down to 7 mm and are thus among the so-called " microdisplays ". Despite their small size LCoS displays can have more than two million pixels, allowing a resolution (1600 × 1200 pixels) is still higher than UXGA. In addition, a maximum contrast ratio of 1000:1.

LCoS displays consist of three parts: a silicon film, a thin layer of liquid crystals on this and a thin pane of glass.

The light from a lamp is directed through a special polarizing mirror to the LCoS display where the liquid crystal molecules are aligned by an electric voltage, so that the light is reflected in the desired brightness. The fill factor of the display is very large (> 90 %), which has a high optical efficiency result. In contrast to the DMD technology, the light must be polarized, so that it can be modulated by an LCoS display. Thus a higher light output is required. However, LCoS projectors have the potential to be even smaller than their counterparts DMD.

The advantage of LCoS compared to conventional LCDs lies in its ability to reflect light, rather than pass. This can be mounted under the reflective layer as necessary to control the thin film transistors traces, and there is no longer a visible grid in the image display ( "screen door effect"). A disadvantage is the opposite micromirror actuators lower linearity between electrical driving signal and light variation.

For the multi-color projection integrated LCoS modules are typically used in a three beam splitters, which are used each for one primary color.

Application

LCoS products are available from several manufacturers, with JVC 's called this method D -ILA technology at Sony SXRD.

For residential consumers, the technology was introduced in Europe in 2005, in digital projectors, which were characterized by a high image resolution and image brightness.

The first mobile phone with built-in projector from the Chinese manufacturer Shengtai uses this technique.

Sony distinguishes 2011, three different generations of LCoS chips: