Imprinted plastic: next generation displays
Sub-micron polymer posts align the liquid crystals in the new display.
Mr John Rudin, Dr Adrian Geisow, Mr Julian Richards and Dr Steve Kitson.
Hewlett-Packard Laboratories, Bristol.
Scientists at Hewlett-Packard Laboratories (HP Labs) in Bristol have developed a new process for building liquid crystal displays (LCDs) that will enable larger screens at high resolutions. Currently, LCDs use glass in their manufacture, limiting display size; also, the numbers of pixels are restricted by the need for images to be refreshed many times a second. John Rudin and his colleagues at HP Labs have overcome these barriers by using plastics and by introducing inherent image stability so that constant screen refresh is not required. 'The digital revolution has made storing, processing and sharing visual information incredibly powerful', says John. 'But the interface between this information and the human brain the visual display is still very limited'. The number of megapixels an image has is an indication of its quality, and is commonly used today to refer to the quality of the photos produced by digital cameras. With current technology, most computer displays or TVs are often only one or two megapixels. The new technology should give screen image quality approaching that of the printed page, which is the equivalent of approximately eight megapixels.
The key to achieving such high resolutions is through a 'bi-stable electro-optic' effect. In current LCDs the liquid crystal changes its optical state when a voltage is applied. Additional polarisers and colour filters produce the final image. However, the liquid crystals revert to their original state as soon as the voltage is removed, meaning that the display needs to be continuously refreshed to maintain the image. For current LCDs of about one megapixel the refresh data rate required is more than one gigabit per second; 50 megapixels would require50 gigabits per second. 'That's the equivalent of the entire contents of a full iPod-mini being transferred every second', explains John. The new system removes the need for constant refresh by having