Liquid crystal on silicon - AbsoluteAstronomy.com

Liquid crystal on silicon (LCoS or LCOS) is a "micro-projection" or "micro-display" technology

Technology

Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. It can also refer to the collection of such tools, machinery, and procedures. The word technology comes ;...

typically applied in projection televisions. It is a reflective technology similar to DLP projectors; however, it uses liquid crystals instead of individual mirrors. By way of comparison, LCD projector

LCD projector

An LCD projector is a type of video projector for displaying video, images or computer data on a screen or other flat surface. It is a modern equivalent of the slide projector or overhead projector...

s use transmissive LCD chips, allowing light to pass through the liquid crystal. In LCoS, liquid crystals are applied directly to the surface of a silicon chip coated with an aluminized layer, with some type of passivation

Passivation

Passivation is the process of making a material "passive", and thus less reactive with surrounding air, water, or other gases or liquids. The goal is to inhibit corrosion, whether for structural or cosmetic reasons. Passivation of metals is usually achieved by the deposition of a layer of oxide...

layer, which is highly reflective.

LCoS technology can typically produce higher resolution and higher contrast images than standard liquid crystal display

Liquid crystal display

A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....

and plasma display

Plasma display

A plasma display panel is a type of flat panel display common to large TV displays or larger. They are called "plasma" displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent...

technologies, which makes it less expensive

Cost

In production, research, retail, and accounting, a cost is the value of money that has been used up to produce something, and hence is not available for use anymore. In business, the cost may be one of acquisition, in which case the amount of money expended to acquire it is counted as cost. In this...

to implement

Implementation

Implementation is the realization of an application, or execution of a plan, idea, model, design, specification, standard, algorithm, or policy.-Computer Science:...

in such device

Display device

A display device is an output device for presentation of information in visual or tactile form...

s as televisions.

History and implementations

General Electric first demonstrated an LCoS display in the late 1970s. As a 'proof of concept' vehicle, it was very low resolution.

The late 1990s saw a number of companies attempt to develop products for near-eye and projection.

At the 2004 CES

Consumer Electronics Show

The International Consumer Electronics Show is a major technology-related trade show held each January in the Las Vegas Convention Center, Las Vegas, Nevada, United States. Not open to the public, the Consumer Electronics Association-sponsored show typically hosts previews of products and new...

, Intel announced plans for the large scale production of inexpensive LCoS chips for use in flat panel displays. These plans were cancelled in October 2004. Sony

Sony

, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

has made it to market (December 2005) with the Sony-VPL-VW100 or "Ruby" projector, using SXRD, 3 LCoS chips each with a native resolution

Native resolution

The native resolution of a LCD, LCoS or other flat panel display refers to its single fixed resolution. As an LCD display consists of a fixed raster, it cannot change resolution to match the signal being displayed as a CRT monitor can, meaning that optimal display quality can be reached only when...

of 1080p

1080p

1080p is the shorthand identification for a set of HDTV high-definition video modes that are characterized by 1080 horizontal lines of resolution and progressive scan, meaning the image is not interlaced as is the case with the 1080i display standard....

(1920 × 1080), with a stated contrast ratio

Contrast ratio

The contrast ratio is a property of a display system, defined as the ratio of the luminance of the brightest color to that of the darkest color that the system is capable of producing...

of 15,000:1 using a dynamic iris.

LCoS technology has the potential to enable the manufacture of big-screen high-definition televisions with very high picture quality at relatively low cost. However, LCoS, while conceptually straightforward, can be a difficult technology to master; a number of companies have dropped out of the LCoS business in recent years. Nonetheless, as of June 2006, proprietary methods for mass-producing LCoS developed, and at least four manufacturers produced LCoS-based rear-projection televisions for the consumer market; with the drop in prices for LCD and plasma

Plasma display

flat panels, consumers stopped buying rear projection sets, and as of July 2010 LCoS-based rear-projection televisions are no longer being made.

Commercial implementations of LCoS technology include: Sony

Sony

, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

's SXRD (Silicon X-tal Reflective Display) and JVC

JVC

, usually referred to as JVC, is a Japanese international consumer and professional electronics corporation based in Yokohama, Japan which was founded in 1927...

's D-ILA (Digital Direct Drive Image Light Amplifier), and Epson's 'reflective 3LCD'. Every company which produces and markets LCoS rear-projection televisions uses three-panel LCoS technology,. This is due to the fact that the HEO_5216_MC_5150 is the highest resolution 'single chip solution' currently available and is only 1280x720. Sony and JVC both produce and market front-projection displays that use three LCoS panels.

Direct-view LCoS devices such as the single-panel LED-illuminated devices made by Displaytech and Forth Dimension Displays (Dalgety Bay, Fife, Scotland) (formerly known as CRLO Displays) are also used as electronic viewfinders for digital cameras, for pico projectors and within Near to Eye (NTE) applications such as Head Mounted Displays (HMDs)

Head-mounted display

A head-mounted display or helmet mounted display, both abbreviated HMD, is a display device, worn on the head or as part of a helmet, that has a small display optic in front of one or each eye .- Overview :...

. These devices are made using ferroelectric liquid crystals (so the technology is named FLCoS), which are inherently faster than other types of liquid crystals. Displaytech was acquired by Micron Technology

Micron Technology

Micron Technology, Inc. is an American multinational corporation based in Boise, Idaho, USA, best known for producing many forms of semiconductor devices. This includes DRAM, SDRAM, flash memory, SSD and CMOS image sensing chips. Consumers may be more familiar with its consumer brand Crucial...

in May 2009, which is continuing to develop the FLCoS technology.

Developers and manufacturers who have left the LCoS microimaging market include: Intel, Philips

Philips

Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....

, MicroDisplay Corporation, S-Vision, Colorado Microdisplay, Spatialight, Syntax-Brillian.

Display system architectures

There are two broad categories of LCoS displays: three-panel and single-panel. In three-panel designs, there is one display chip per color, and the images are combined optically. In single-panel designs, one display chip shows the red, green, and blue components in succession with the observer's eyes relied upon to combine the color stream. As each color is presented, a color wheel (or an RGB LED

LEd

LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....

array) illuminates the display with only red, green or blue light. If the frequency of the color fields is lower than about 540 Hz, an effect called color breakup is seen, where false colors are briefly perceived when either the image or the observer's eye is in motion. While less expensive; single-panel projectors require higher-speed display elements to process all three colors during a single frame time, and the need to avoid color breakup makes further demands on the speed of the display technology.

Three-panel designs

In a DLP device the light is separated into three components and then combined back: Two beam splitter

Beam splitter

A beam splitter is an optical device that splits a beam of light in two. It is the crucial part of most interferometers.In its most common form, a rectangle, it is made from two triangular glass prisms which are glued together at their base using Canada balsam...

s are needed.
In LCoS devices the light is additionally polarized and then analyzed; four beam splitters are needed. In most DLP sets a color wheel separates colors from a lamp, using one chip for all three colors; SXRD sets use three separate chips, one for each color.

One-panel designs

Both Toshiba's and Intel's single-panel LCOS display program were discontinued in 2004 before any units reached final-stage prototype. There were single-panel LCoS displays in production. One by Philips

Philips

Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....

, one by Microdisplay Corporation and one from Forth Dimension Displays. Forth Dimension Displays have a Ferroelectric LCoS display technology (known as TDI) (available in SXGA and 720P resolutions) which is mainly, but not exclusively, used in high resolution NTE applications such as Training & Simulation. Micron's FLCoS technology is another single panel RGB solution used in pico projectors and near-eye display applications.

External links

Biever, Celeste. 'Intel inside' comes to flat panel TVs (January 9, 2004 – No longer planned for development) NewScientist.com.
contrast vs brightness
D-ILA Technology Explained, JVC
D-ILA Projector Technology, Avitav
"Display Technologies" 1992 to Present, Displaytech Inc.
LCoS displays Holoeye Photonics AG.
LCoS displays Forth Dimension Displays.
Everything You Need to Know About TV Technologies
Game-Changing Displaytech FLCoS Microdisplay Technology — micron.com

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History and implementations

Display system architectures

Three-panel designs

One-panel designs

See also

External links