Step to 30inch polymer TV
The prototype is seen as a "carve-out" for the companyÕs reference application - a wide-screen 30inch diagonal display with WXGA (1365x768pixels) resolution. The carve-out has a resolution of 576x324pixels to demonstrate the feasibility of manufacturing large-screen polymer OLED displays using high-accuracy multi-nozzle, multi-head inkjet printers.
The company claims an "excellent and sparkling image quality" for the prototype. Based on current predictions, the company hopes that a polymer OLED-based TV could be a reality in the next five years.
Polymer OLED displays offer advantages over current LCD displays in terms of wide viewing angle and fast response time Ð useful for moving video. It also offers improved black-level performance and picture contrast since a polymer OLED display is emissive. This also means that the technology requires no backlight and can therefore be manufactured in exceptionally thin form-factors, enabling displays no thicker than a pane of glass, without compromising display characteristics.
Philips Research has developed an inkjet printing process using a four print-head printer equipped with 256 piezo-driven nozzles. Together with the PolyLED material suppliers and print head manufacturer Spectra, Philips has developed inks, print heads and substrate processes. The system uses a novel printing method in which each sub-pixel (R, G or B pixel) is built up from multiple droplets fired from different nozzles. The system is capable of printing displays up to 24 inches. Larger displays will be made possible simply by increasing the size of the printer.
The PolyLED-TV display uses a number of video processing technologies to enhance the image quality further. A novel addressing scheme is implemented that varies the duty cycle for each display line depending on the image load: in dark scenes, a high local peak brightness is combined with the perfect black state of OLEDs, while in bright scenes the brightness is kept at an average value. The purpose of this is to produce sparkling images with greatly improved perceived image quality. Colour processing is used to further improve the overall image perception.
Philips is already using OLED displays in products such as its latest 639 mobile phone with 'Magic Mirror'. In 2002, Philips became the first company to launch polymer-based OLED displays for consumer applications (in a shaver).