TV manufacturers have shown off ultra-thin OLED TVs as concepts at trade fairs for the past several years, but they finally hit stores in some parts of the world in late December 2012. The models are between 4 and 8 mm thick and are not exactly cheap—the first ones cost somewhere between Rs 5 to 6 lakh. However, image quality has taken a quantum leap and OLED TVs will be a lot more affordable once mass production begins. For mobile devices, a new generation of small screens with HD resolution is already available. In the future, these devices will be even slimmer thanks to new technologies. E-book readers with colour e-ink displays are already being sold in parts of Asia, and it is only a matter of time before they will become more mainstream.
Futuristic concepts are available today
A lot of technologies that we will use in the future seem strange; almost like science fiction. Interactive data glasses, see-through touchscreen displays and flexible e-book readers are only a few of the things that are already quite possible. Even common consumer devices will eventually move to materials and manufacturing processes that improve their performance and efficiency. This means that things like displays on car windscreens and images on artificially generated fog will soon be commonplace. It seems as if researchers are using any possible surface to display an image on. There’s lots of excitement in this industry, and we’re here to show you which ones have the most potential and which visions will become reality soon.
Television: Organic light
LG's 55 inch OLED TV is just 4 mm in depth
TVs with edge-mounted LED backlights are common in thin displays today, but this results in uneven surface illumination and low contrast. A lot of manufacturers are equipping their top models with direct LED backlights to put things right. This is a back panel comprised of white LEDs that illuminates the LCD-TFT panel directly from behind. As individual LEDs can be switched off, parts of the screen appear darker and the contrast values are better than with edge-mounted LEDs. Sony goes a step further— its 55-inch Crystal LED panel, which is ready to go into production, does not have any kind of backlight or LCD technology at all. Each pixel consists of three micro-diodes in red, green and blue—up to 62,20,800 actual LEDs in an array for full HD resolution (rather than today’s LEDs which are used for backlighting only). Sony says the panel has 3.5 times better contrast, a 40 percent wider colour palette, super-fast response times and wider viewing angles.
TFT displays - the position of the controllable liquid crystals and the backlight limits how evenly lit an image can be. Instead, by using LEDs behind the TFT some areas of the backlight layer can be dimmed or switched off to increase contrast in an image
OLED TVs are energy-efficient and high in contrast thanks to the use of organic light-emitting diodes. They do not need a backlight as the pixels themselves emit light. Samsung and LG have already exhibited 55-inch prototypes but have a few hurdles to overcome, namely distorted colour reproduction and low life expectancy. While the Samsung ES9500 uses three colour OLEDs arranged side by side for each pixel, LG’s 55EM96OV works with white light and RGB colour filters. Three OLEDs are positioned behind every colour sub-pixel, which together generate white light. A fourth white LED provides more brightness. Without a backlight, the TVs are extremely slim. The Samsung model is hardly 8 mm thick and LG has managed to bring it down to 4 mm.
Behind every colour filter are three-layered red, green and blue OLEDs. These together produce white light, the brightness of which is controlled by the luminosity of the OLEDs. A white sub-pixel in each pixel provides additional brightness
Displays you can look right through
Large transparent displays are still in the concept stage. Only Samsung has started manufacturing its Smart Window LTI460AP01, which is almost as transparent as glass when not switched on. Such screens don't need a frame, but only a casing on the edges to hold electronics and loudspeakers. An image in full HD resolution appears when the device is switched on. The screen can be made transparent by combining conventional LCD technology with the new TOLED technology (Transparent OLED). Samsung’s smart TV can be used as a display for videos, apps and widgets. The resolution of the 46-inch panel is 1680 x 1050 pixels, and it has a contrast ratio of 500:1. Applications can be operated via remote control. The surrounding ambient light serves as the light source; edge-mounted LEDs are activated only if required, which means the device consumes very little power. A cool feature is that smart windows can be darkened with an app called Jalousie (blinds). Just pull a virtual cord and the blades of the virtual blinds close, making the glass panel opaque.
Minority Report says hello: The Smart Window from Samsung is an interesting mix of a transparent touch panel and a TFT screen. The image contents appear to float almost as if in free space, as you can see in the live product demonstration
Mobile devices: Sharp display
The PenTile display of the Samsung Galaxy S3 has a high resolution but needs very little power
Samsung’s Galaxy smartphones have popularised AMOLED displays. Its latest smartphones as well as the extra-large Note "Phablet" also rely on this proven technology, but with a PenTile active matrix. As opposed to conventional RGB displays, the subpixels on a PenTile matrix are of different sizes and are arranged differently. While RGB displays usually have a red, green and blue subpixel for every pixel, PenTile employs only a green and red or blue subpixel for every alternate pixel (RGBG). According to Samsung, PenTile displays consume less power and last longer as blue subpixels are prone to malfunctioning. Furthermore, it is also possible to create small AMOLED screens at HD resolution with PenTile. Some Galaxy S3 users have complained about blurred displays and colour deviations, but Samsung says that this effect only appears at low resolutions. Our tests have confirmed these statements. The displays of the Galaxy S3 and Note are impressive with their bright colours and high contrasts.
TFT and OLED technology in comparison
Colour displays for e-book readers
Apple has broken new ground with the iPhone 5. Until now, the display and touch panel of all gadgets were overlaid in a sandwich design, but the company has fused the touch sensors directly to the LCD glass. This reduces the overall height of the display, resulting in the iPhone 5 being only 7.6 mm thick; its predecessor, the 4S, was 9.3 mm thick. Industry insider and analyst Hiroshi Hayase of DisplaySearch confirms that this also results in better viewing angles. For this purpose, Apple utilises the In-Cell manufacturing process of Sharp, LG Display and Japan Display. Thus, Apple can do away with a separate touch panel supplier.
Apple has used in-cell technology with its iPhone 5. The touch sensors are built right into the display. In addition to reducing thickness, the display is located immediately below the protective glass, which improves viewing angles considerably
E-ink displays are generally used by e-book readers
They only consume power while pages are being turned. Unfortunately, such displays have been available only in grey tones until now. Mirasol has changed this with its bi-stable, coloured, reflective iMod displays. MEMS (microelectromechanical systems) are at the core of this technology. Every pixel has two stable states: transparent and light absorbing. Mirasol controls which coloured subpixels will be illuminated with reflected light. The image is locked on the screen even after the signal has been received and the power shut off. The Kyobo Reader is the first to come with a coloured E-ink screen. Other devices that utilise Mirasol displays have been introduced, such as the Hanvon C18, but these are not widely available outside East Asian markets yet. All three are based on the same hardware and have 5.7-inch Mirasol displays with capacitive touchscreens at a resolution of 1024 x 768 pixels; they are powered by a 1GHz Snapdragon processor.
Some e-readers reproduce coloured images with micro-electromechanical systems (MEMS). The Kyobo was the first such device. It is re-branded by Hanvon and Bambook, but only in Asia. Mirasol promises to make such displays more common soon
Research: A bright future
British company Plastic Logic specialises in organic electronics based on plastics and has come up with a process for manufacturing flexible displays. It applies active matrix TFTs to plastic film and combines this with e-ink electronics. Only the silicon-based external driver and multiplexer chips restrict the flexibility of the displays, which can be as thin as sheets of paper. Prototypes with flexible organic driver circuits already exist. Currently, Plastic Logic manufactures 10.7-inch displays with a resolution of 1280 x 960 pixels, which means a density of 150 ppi. The display uses incidental light and does not have its own light source. It is so flexible that it can be rolled up. Furthermore, damage to small areas does not render the entire display unusable; only some lines and columns are damaged. The e-paper is bi-stable and only requires power while changing the image displayed. Besides grey tone displays, Plastic Logic can also produce colour displays. For this purpose, the company employs colour foils with red, green, blue and white filters over and above the grey tone pixels. At present, it is possible to render 4,096 colours. Admittedly though, their saturation is very low.
Plastic Logic combines a proprietary TFT backplane with an E-Ink frontend for a flexible display. Both items are made of plastic and are therefore flexible. An additional colour filter array also enables the display of basic coloured image contents
Smart glasses could replace smartphones. Every device has a display these days, but tomorrow, maybe none will need to. With the Project Glass smart glasses, Google can conjure up information and images before your very eyes. The slender frame is equipped with a CPU, memory, camera, microphone, compass, GPS, gyroscope, Wi-Fi and Bluetooth. With a well-functioning speech control system, the glasses even have the potential to replace smartphones in the long term. Google has already displayed prototypes to the public. Glass should be ready for the market in 2014; a developer version costing US$ 1,500 (Rs 81435 approx) will be available in 2013.
The heads-up display Carrozzeria Cyber Navi AR from Pioneer seems to project floating image content ahead of the car, which could include navigation instructions. The system uses different coloured lasers and a micro-mechanical mirror instead of TFTs
Heads-up displays have not taken hold in the automobile industry yet, but Pioneer wants to change that. While currently prevalent HUDs operate like projectors, Pioneer uses the HD PicoP Gen2 laser technology by MicroVision in its Carrozzeria Cyber Navi AR HUD. The device casts rays of red, green and blue lasers on a controllable micro-mirror. This builds up a composite image. The colour and brightness of each pixel can vary depending upon the intensity of the laser. The best part is that an image of 90 x 30 centimeters can be displayed in perfect sharpness at a distance of about three metres in front of the driver’s eyes, seemingly floating in front of the car. The driver doesn't need to constantly refocus his eyes from the windshield itself to the road ahead in order to see the virtual instrument panel.
Originally developed at the University of Tampere in Finland, interactive content is projected onto an invisible wall of artificially produced fog. Meanwhile, the company FogScreen already has different versions available to consumers.
Photos: Arts-Fx (France) / Fogio (Finland) Photography Courtesy of Plastic Logic, Sony Pictures Of "Skyfall"
Illustrations: Barbara Hirtenfelder