EVOLUTION

The manufacturing of flat panel displays is a dynamic and continuously evolving industry. Improvements of flat panel displays are made rapidly as technology improves and new discoveries are made by display scientists and engineers. The cathode ray tube and active matrix liquid crystal display (LCD) recently celebrated their 100th and 25th anniversary, respectively. The arrival of portable electronic devices has put an increasing premium on durable, lightweight and inexpensive display components. In recent years, there has been significant research investment in the development of a flexible display technology.





Organic LEDs on glass substrates are already making their way into consumer products such as digital cameras and electric shavers, but the first products to incorporate flexible displays will likely be electronic books, paper, and signage. While products are initially being built on glass substrates, the shift to flexible substrates is under way.


Rollable-display initially focused on electrophoretics, a low-power-consumption display technology better known for its role in e-paper, e-books, and e-signage.Gyricon's Smart Paper, for example, is produced in a roll like conventional paper but is actually two sheets of thin plastic with millions of tiny bichromal beads embedded in between. E Ink uses stationary microcapsules that contain white particles, black particles, and a clear fluid OLEDs are self-luminous and do not require backlighting, polarizer, or diffusers, which reduces the size and weight. In addition, they offer a wide viewing angle and low power consumption. While OLEDs are not yet as bright as other displays, efforts are under way to improve this. When it comes to putting OLEDs on polymer or metal-foil substrates, proponents say there is a symbiotic relationship between the materials and the production processes that make OLEDs a natural fit for flexible displays.

It turns out that the OLED manufacturing process, because it is all chemical, is much more amenable to retaining optimum performance on a flexible surface than other display technologies such as LCDs.There are still some key technology limitations to be overcome—most notably the extreme sensitivity OLEDs have to moisture and oxygen. Another key factor in transitioning OLED, LCD, and electrophoretic displays onto polymer or metal involves the TFT backplanes, which must also eventually reside on plastic in order to achieve a truly flexible display.

Another approach is to eliminate the temperature issue altogether by using organic transistor materials for TFTs that can be printed directly on plastic.
Polymer Vision, a division of Philips, has been able to make organics-based QVGA (320 × 240 pixels) active-matrix displays with a diagonal of 5 in., a resolution of 85 dpi, and a bending radius of 2 cm. The displays combine a 25-µm thick active-matrix backplane containing the polymer electronics-based pixel drivers, with a 200-µm front plane of reflective "electronic ink" developed by E Ink (see photo, [right]). With nearly 80,000 TFTs, the resulting display is the largest organic electronics–based display yet.