Handbook for Sound Engineers

The Fundamentals of Display Technologies 1587

44.8.4 Liquid Crystal on Silicon

Liquid crystal on silicon combines the best of both
worlds of LCD and DLP. It is a reflective technology
like DLP but uses liquid crystals instead of moving mir-
rors to control the light transmission levels of the indi-
vidual pixels. The benefit of LCoS is that it has
excellent color and contrast capabilities and has the
highest fill factor of any current digital display. It is also
capable of 4 K resolution and is a competitor with DLP
for digital cinema applications, Fig. 44-6.

44.8.4.1 LCoS Characteristics

• Projection technology, no fixed screen size.


• Three chip configuration.


• 16:1 aspect ratio panels.


• No radiation or high voltage emissions.


• Low power consumption.


• High resolution, up to 4 K.


• High brightness and contrast.


• High fill factor.

44.8.4.2 LCoS Operates in the Following Manner

• LCoS technology is a reflective liquid crystal modu-
  lator where electronic signals are directly addressed
  to the device.


• The LCoS device has an X-Y matrix of pixels config-
  ured on a CMOS single crystal silicon substrate
  mounted behind the liquid crystal layer using a planar
  process that is standard in IC technology.


• The liquid crystal is placed on top of the CMOS
  substrate on an array of aluminum mirrors that define
  each pixel.


• A glass counter electrode covers the liquid crystal to
  complete the structure.
  
  
  • A voltage is applied to a selected pixel of the matrix
    in accordance with the input signal, making the liquid
    crystal change birefringence, thus changing the polar-
    ization direction of the incident projection light.
  
  
  • The nonactive area between the pixel mirrors is
    minimal, only serving to separate each pixel; the rest
    of the electrode is active as a reflective surface,
    thereby providing a high aperture ratio.
  
  
  • Although having the highest overall performance of
    any current projector technology it is held back by
    manufacturing yield issues and cost of components
    that impede its progress.
  
  
  
  

44.8.5 Organic Light Emitting Diode

Organic light emitting diode (OLED) is the newest dis-

play technology and a direct competitor for other flat

panel displays such as LCD and plasma. The most obvi-

ous benefit is the nearly paper thinness of the technol-

ogy. Since it is an emissive technology that does not

require separate lighting it can be manufactured to cre-

ate a display the thickness of a credit card. It can be

made transparent and even flexible. It also has advan-

tages in the area of low power consumption and excel-

lent picture performance dynamics. The big issues

facing OLED are manufacturing costs, and panel life,

both of which are in the process of being addressed.

44.8.5.1 OLED Characteristics

• Thinnest and lightest display technology.


• Fast response time.


• High brightness.


• Low power consumption.


• Can be made transparent or flexible.

Figure 44-6. LCoS projection system.