Liquid crystal displays could soon be painted straight on to surfaces, using a technique currently being refined by researchers at Philips laboratories in the Netherlands.
The process removes the need to sandwich liquid crystals between two layers of plastic or glass. Instead, a liquid crystal mixture is painted directly onto a surface and then treated with ultraviolet light.
“This paves the way for completely different methods of making displays,” Philips researcher Giovanni Nisato told Â鶹´«Ã½. “Even if for some reason it cannot compete with existing techniques, it creates new possibilities.”
Nisato says the technique could potentially allow manufacturers to make displays more quickly because the liquid crystal mixtures do not have to be carefully poured between two surfaces. But he also says the method is a long way from being used in industrial production. So far, the team has constructed a square display 2.5 centimetres wide.
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“It is very interesting but has to be put in perspective,” says Peter Raynes, of Oxford University. “Lower resolution, simple displays over a large area on anything could be possible. But high resolution, high performance displays would need much more development.”
Grid pattern
The liquid crystal mixture is painted across a surface covered with electrodes and then treated with two different wavelengths of UV light. The first treatment solidifies part of the mixture to create a grid. This separates the surface into different cells, which act as the pixels of the display. The second light treatment creates a hardened layer above the cells.
Conventional LCDs pass current between the top and bottom layer to switch the cells on and off. The current “twists” the crystals, altering their ability transmit light. But the new display changes the alignment of the crystals by altering the current flowing between the electrodes on only the lower surface.
Raynes says the researchers need to tackle a few issues before the technique is ready for widespread use. These include controlling the thickness of the resulting liquid crystal layer painted onto a surface and ensuring that crystals can be controlled accurately enough.
Journal reference: Nature (vol 417, p 55)
