User Tools

Site Tools


flexible_displays

Flexbible display technologies

Tech Overview

Cathode Ray Tubes Displays (CRT)

The video display unit that comprises the majority of today's television and computer monitors. CRTs are relatively heavy vacuum-sealed glass containers with a screen on one end. The CRT's screen is illuminated by electrons, which are projected at a phosphor coating on the inner surface of the screen.

Electroluminescent displays

A colored light emitting display. Light is created by electrically stimulating electroluminescent semiconductors. EL displays are emissive devices. Instead of modulating a backlight, as LCDs do, EL displays produce their own light by applying a voltage to a phosphor. With AMEL (active-matrix electroluminescent) displays, each pixel site on the display has its own transistor. All the drive electronics and pixel transistors are fabricated in a modified silicon foundry. Phosphors are then deposited directly onto these electrons.

Ferro-electric liquid crystal displays

A display in which light polarization is changed under influence of electric field. Conventional LCD materials need a continuous field, FELCD does not as it is bi-stable. High contrast (40:1) and a wide viewing angle can be obtained. Lack of gray scales makes them suitable for computer displays but not for TV.

Field emission displays (FED)

An array of microminiature CRTs that bombard phosphors with electrons over very short distances. FED panels are similar to CRTs in that a front layer of phosphors gives off light when excited by emitted electrons. FED panels place hundreds of tiny electron emitters behind each pixel, in panel a few millimeters thick. The effect is a digital panel in which each panel is controlled directly, but where light is emitted by the phosphors at the individual pixel as in a CRT.

Liquid Crystal Displays (LCD)

A display composed of liquid crystal suspended between two transparent sheets. The display is composed of pixels or other shapes which can be turned on or off with electrical stimulation. Typically a light is passed through the LCD to illuminate the pixels. Custom passive LCDs address most display needs and requirements for high performance, increased information content, low power, and low cost.

TN-LCD (Twisted Nematic)

The lowest cost material and mature technology that offers high contrast (darkness of characters compared to background screen). This material is limited to low information content displays, such as basic calculators and toys.

STN-LCD (Super Twisted Nematic)

A low cost material and mature technology that offers good contrast for medium to high information content displays, such as cellular telephones and PDAs.

FSTN-LCD (Film Compensated Super Twisted Nematic)

A medium cost material and progressing technology that offers very good contrast for medium to high information content, monochrome and gray scale displays, such as cellular telephones and PDAs. Its appearance is black characters on a silver background.

Active Matrix Liquid Crystal Displays (AMLCD)

AMLCD composed of a rear glass substrate patterned with thin-film transistors. TFTs, a front glass substrate with color filters and a liquid crystal material filling the middle between the glass “sandwich”. The array of thin-film transistors on the rear substrate is attached to electronic drivers that receive impulses from a computer chip attached to the host system. Each TFT acts as an on/off switch to activate a pixel, force the liquid crystal to twist, and allow light to pass through and form images on the display. Most AMLCDs use either an amorphous silicon or poly-silicon layer of semiconductor material within the TFT array.

Liquid Crystal on Silicon (LCOS)

An alternative way to create high-resolution images with liquid crystals involves the use of Liquid Crystal on Silicon (LCOS) devices. LCOS devices use only one glass substrate, and employ a silicon surface for the back of the display. Silicon processing technology is advanced to the point that patterning several million pixels and their related drivers on a 1-inch square section of crystal is easily done. The pixels are then generally coated with a reflective aluminum layer, and then a polyimide alignment layer. Thus, the liquid crystal industry can piggyback off of existing silicon technology to allow for a high resolution microdisplay that is easy and inexpensive to manufacture.

Light-Emitting Diodes (LED)

is an electronic component, which glows when electricity flows through it. LEDs light like a bulb, but they only use a fraction of the power. This means that batteries will last longer if LEDs are used instead of bulbs.

Microdisplay

A small, high-resolution display (size of a thumbnail) that when combined with projection optics, has the unique advantage of being able to magnify and project an image that is much larger then the display itself. Microdisplays are typically less than 1.0“ diagonal, but can offer resolutions from 1/4 VGA (78 thousand pixels) to UXGA+ (over 2 million pixels). Microdisplays are ideal for wireless, portable, lightweight products. The two basic markets for microdisplays are projection and near to eye (NTE) applications.

Organic LED Displays (OLED)

This type of display is made possible by the development of polysilicon technology (PolySi) which, because of its high carrier mobility, provides thin-film-transistors (TFT) with high-current carrying capability and high switching speed. The passive-matrix OLED display has a simple structure and is well suited for low-cost and low-information-content applications such as alphanumeric displays. In contrast to the passive-matrix OLED display, an active-matrix OLED has an integrated electronic backplane as its substrate and lends itself to high-resolution, high-information-content applications including videos and graphics.

Plasma Display Panels (PDP)

Electrons are removed from atoms to produce ions, later recombining with the ions and releasing energy in the form of light. A certain trigger (or priming) voltage is required to start the ionization process, after which the process will continue at a lower voltage and the brightness of the emission will depend directly upon the current passing through the ionized gas, known as a plasma. Two sheets of glass with a conductive film and a mixture of gases that glow when excited by a current: being used for large-format color screens. src: http://www.usdc.org/

FOLEDS

FOLEDs are organic light emitting devices built on flexible substrates. Flat panel displays have traditionally been fabricated on glass substrates because of structural and/or processing constraints. Flexible materials have significant performance advantages over traditional glass substrates. src: http://www.universaldisplay.com/foled.php

TOLEDS

The Transparent OLED (TOLED) uses a proprietary transparent contact to create displays that can be made to be top-only emitting, bottom-only emitting, or both top and bottom emitting (transparent). TOLEDs can greatly improve contrast, making it much easier to view displays in bright sunlight.

toled-an1.jpg

Because TOLEDs are 70% transparent when turned off, they may be integrated into car windshields, architectural windows, and eyewear.

Their transparency enables TOLEDs to be used with metal, foils, silicon wafers and other opaque substrates for top-emitting devices.

src: http://www.universaldisplay.com/toled.php

Siemens

Products

ELastolite

Loop.GIF

Pliability of ELastolite's thin, rubber-like material, which is completely unlike the stiff plastic film that's standard in the industry. In technical terms, ELastolite is an elastomeric material made of polyurethane. This gives ELastolite a bending radius of .08” (2.0 mm) – meaning it's much more flexible than other EL lighting. Our process creates a lamp that is .01“ (.25 mm) thin, with an unlit border of only .04” (1.0 mm) from any edge. The lamps are foldable, crushable, moldable, water and UV resistant. Elastolite can even be in-molded.

src: http://www.oryontech.com/

Rollable LCD

Microchip-Electronic-Driver.gif

At Visson’s Research & Development (R&D) laboratories our team of dedicated and highly qualified scientists has developed a unique method to produce an unparalleled truly rollable bi stable (Cholesteric) liquid crystal display. Cholesteric or bi stable LCD’s have an advantage over conventional LCD’s in that with Cholesteric LCD’s the image remains ‘frozen’ on the display even when the power is turned OFF. This has particular advantage when reading lengthy text such as emails, or for electronic books. The diagram is showing the passive addressing of each pixel through the electrode columns & rows.

Bi stable LCD holds the image in memory without any applied power. Power is applied only when the display is updated to display a new image.

src: http://www.visson-lcd.co.uk/

Philips/Polymer Vision flexible LCD

The monochrome 4.7in, 320 x 240 display is thin enough to be rolled into a curve with a radius of 2cm, the company said.

PV's trick is to build the display's 76,800-odd transistors onto a plastic base rather than glass, the material used in almost all LCDs currently found in phones, PDAs and notebook PCs. home3.jpg

The active matrix component is just 25 microns thick. Above that is a 200 micron 'electronic ink' panel from E-Ink, a non-volatile display system that contains charged black and white particles. Controlled by an electric field, the particles adhere to the panel, allowing them to stay there when the current is removed. Power is only needed to change the image, not to maintain it, making the technology suitable for very low power applications.

src: http://www.theregister.co.uk/content/54/35137.html

LEPs

LEP displays are constructed by applying a thin film of the light-emitting polymer onto a glass or plastic substrate coated with a transparent electrode. A metal electrode is sputtered or evaporated on top of the polymer. Application of an electric field between the two electrodes results in emission of light from the polymer.

The LEP display has a number of very attractive features. The response time is fast (sub-microsecond) and unaffected by temperature. Light emission occurs at low voltages (< 5 V), and the intensity of light is proportional to current. If the electrodes are patterned in orthogonal X and Y lines, light is emitted from the area at the intersection of lines, as occurs in typical matrix displays.

The technology combines the solid state, relatively simple construction and low voltage drive benefits of traditional LEDs with large area patternability associated with non-emissive display technologies such as LCDs. This provides a powerful technology base for building high information content displays.

Unlike liquid crystal, field emission, or plasma displays, which require thin film processing on two glass plates, LEPs can be totally fabricated on one sheet of glass or plastic. This greatly simplifies processing and reduces cost. Additionally, the ability to manufacture devices on flexible plastic substrates introduces new form factor opportunities that will allow displays that conform to unique, non-planar shapes to be produced.

src: http://www.cdtltd.co.uk/

ELUMIN8

EL manufacturer: http://www.elumin8.com/

(site coming up…)

Application Areas

Media Shelters

Flexible displays can have an interesting application in the design of (mobile) media shelters, fully immersive MR spaces, that can be either built permanently, or designed as TAZs. Interesting models to look at can be nests, cocoons, hives, and lairs or huts, haystacks, and baskets, created by interweaving twigs (fibres, display lines…)

Wearable media for mobile gaming

Using flexible displays and kinetic/biometric (…) sensing technologies, and wearable computing, responsive displays can be integrated in the players' clothing. Interaction between the wearer and the material, between two or more wearers, between the wearer and the environment can affect the patterning/light emission/colour across the material. The interaction algorhitms could depend on the players' role/mastery/location in the game - eg. the lighting patterns could become infectious (bleed patterns over to other wearers), mutators (soak up other patterns and mutate them), deadly (freeze the image on other wearers' displays….

(Curiosa)

Resolution

Measure or image output capacity, usually measured in dots per inch (dpi). The number of pixels in an image. The higher resolution, the more detail is available. The following are the more common resolutions:

  • Video Graphics Array (VGA) 640 pixels by 480 lines
  • Super VGA (SVGA) 800 pixels by 600 lines
  • Extended Graphics Array (XGA) 1024 pixels by 768 lines
  • Super Extended Graphics Array (SXGA) 1290 pixels by 1024 lines
  • High Definition Television (HDTV) 1920 pixels by 1120 lines

Libarynth > Main Web > ActiveMaterials > FlexibleDisplays r8 - 24 Oct 2005 - 18:16


flexible_displays.txt · Last modified: 2007/06/10 11:20 (external edit)