Ferroelectric liquid-crystal display (FLCD) is a display technology based on the

ferroelectric In physics and materials science, ferroelectricity is a characteristic of certain materials that have a spontaneous electric polarization that can be reversed by the application of an external electric field. All ferroelectrics are also piezoel ...

properties of chiral smectic

liquid crystal Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals. For example, a liquid crystal can flow like a liquid, but its molecules may be oriented in a common direction as i ...

s as proposed in 1980 by Clark and Lagerwall. Reportedly discovered in 1975, several companies pursued the development of FLCD technologies, notably

Canon Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the material accepted as officially written by an author or an ascribed author * Literary canon, an accepted body of works considered as high culture ** Western canon, th ...

and Central Research Laboratories (CRL), along with others including

Seiko , commonly known as Seiko ( , ), is a Japanese maker of watches, clocks, electronic devices, and semiconductors. Founded in 1881 by Kintarō Hattori in Tokyo, Seiko introduced the world's first commercial quartz wristwatch in 1969. Seiko is ...

, Sharp,

Mitsubishi The is a group of autonomous Japanese multinational companies in a variety of industries. Founded by Yatarō Iwasaki in 1870, the Mitsubishi Group traces its origins to the Mitsubishi zaibatsu, a unified company that existed from 1870 to 194 ...

and GEC. Canon and CRL pursued different technological approaches with regard to the switching of display cells, these providing the individual

pixels In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest addressable element in a dot matrix display device. In most digital display devices, pixels are the sma ...

or subpixels, and the production of intermediate pixel intensities between full transparency and full opacity, these differing approaches being adopted by other companies seeking to develop FLCD products.

Development

By 1985, Seiko had already demonstrated a colour FLCD panel able to display a 10-inch diagonal still image with a resolution of . By 1993, Canon had delivered the first commercial application of the technology in its EZPS Japanese-language desktop publishing system in the form of a 15-inch monochrome display with a reported cost of around £2,000, and the company demonstrated a 21-inch 64-colour display and a 24-inch 16-greyscale display, both with a resolution and able to show "GUI software with multiple windows". Other applications included projectors, viewfinders and printers. The FLCD did not make many inroads as a direct view display device. Manufacturing of larger FLCDs was problematic making them unable to compete against direct view LCDs based on nematic liquid crystals using the Twisted nematic field effect or In-Plane Switching. Today, the FLCD is used in reflective microdisplays based on

Liquid Crystal on Silicon Liquid crystal on silicon (LCoS or LCOS) is a miniaturized reflective active-matrix liquid-crystal display or "microdisplay" using a liquid crystal layer on top of a silicon backplane. It is also known as a spatial light modulator. LCoS initia ...

technology. Using ferroelectric liquid crystal (FLC) in F LCoS technology allows a much smaller display area which eliminates the problems of manufacturing larger area FLC displays. Additionally, the

dot pitch Dot pitch (sometimes called line pitch, stripe pitch, or phosphor pitch) is a specification for a computer display, computer printer, image scanner, or other pixel-based devices that describe the distance, for example, between dots ( sub-pixels) ...

or pixel pitch of such displays can be as low as 6 μm giving a very high resolution display in a small area. To produce color and grey-scale, time multiplexing is used, exploiting the sub-millisecond switching time of the ferroelectric liquid crystal.

Application

The microdisplays find applications in 3D head mounted displays (HMDs), image insertion in surgical microscopes, and electronic

viewfinder In photography, a viewfinder is a device on a camera that a photographer uses to determine exactly where the camera is pointed, and approximately how much of that view will be photographed. A viewfinder can be mechanical (indicating only direct ...

s where direct-view LCDs fail to provide more than 600 ppi resolution. Ferroelectric LCoS also finds commercial uses in Structured illumination for 3D-

Metrology Metrology is the scientific study of measurement. It establishes a common understanding of Unit of measurement, units, crucial in linking human activities. Modern metrology has its roots in the French Revolution's political motivation to stan ...

and

Super-resolution microscopy Super-resolution microscopy is a series of techniques in optical microscopy that allow such images to have Optical resolution, resolutions higher than those imposed by the Diffraction-limited system, diffraction limit, which is due to the diffra ...

. Some commercial products use FLCD. High switching speed allows building

optical switch An optical transistor, also known as an optical switch or a light valve, is a device that switches or amplifies optical signals. Light occurring on an optical transistor's input changes the intensity of light emitted from the transistor's output ...

es and shutters in printer heads.WTEC Library
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References

{{emerging technologies, displays=yes Liquid crystal displays Display technology

Development

Application

See also

References