Thin flexible video displays based on novel technology are the subject of a £12m government-supported project.
The project's electrowetting intellectual property comes from Liquavista, a Philips spin-out with offices and R&D in Cambridgeshire.
"Colour and video capability will broaden the application of electronic paper displays to all types of content and device," said Liquavista CEO Mark Gostick. "Together with our partners Plastic Logic, and with the help of the Technology Strategy Board, we are aiming to realise the full potential of electronic paper displays as the best way to show any content on the move."
Polymer transistor firm Plastic Logic is based on the Cambridge Science Park, and is already manufacturing thin flexible electrophorescent e-paper displays using materials from E Ink.
Electrowetting involves a water-filled pixel with a tiny drop of oil stuck to its rear surface.
The rear surface has a fluorocarbon coating that is hydrophobic, but turns hydrophilic when an electric field is applied via an electrode in the water.
In the neutral state the oil spreads out evenly across the rear surface, but when the field is applied the water pushes the oil away into the corners of the cell exposing the rear surface.
By using coloured oil, and a differently colour or transparent rear surface, all sorts of colour combinations can be switched - within a few milliseconds v-p marketing Simon Jones told Electronics Weekly.
An early electrowetting display. Pale and dark fish are pixels that are off and on respectively.
"For example, green oil exposing a metallic effect underneath, or black oil with a backlight, or we can produce a luminous backing that is stimulated through the oil," he said.
Contrast is 6:1 to 8:1 compared with paper at 8-15:1, said Jones, adding: "With a white backing we get a very bright white which increases the apparent contrast. The LCD in a watch typically reflects under 25%. Our's typically reflects over 40%."
For glass-based electrowetting displays, front and back-end processes are almost exactly the same as for LCD manufacture, and the firm has partnered with an LCD fab for production.
"The completely different part is the middle bit," said Jones. This involves depositing sheep pen-like structures to trap each pixel's oil drop. The pens are open-topped as the oil tenacious grips the rear face. "Forces on the microscopic scale are huge," said Jones. "The displays are resilient to shaking and any kind of physical duress."
He points out that there is nothing exotic in the pixels, only oil, water and dye. The dyes are chose to be UV-resistant and the only wear-out mechanism is the gradual fading any dye will suffer, which will take many years.
Several customers have products in development, which are expected on the shelves in the first half of next year.
At least one of these is a watch. "The watch market is crying out for something different, there is very little opportunity to make a fashion watch out of LCD," said Jones, citing watch design-ins as confirmation of Liquavista's low power consumption claims.
Another product in development is a decorative display for the back of a mobile phone.
All the applications so far are for directly-driven segments with one driver per pixel.
While the technology is compatible with passive matrix addressing, said Jones, the firm has decided not to develop the custom silicon required, but to go straight to active matrices for video displays, which is where the Plastic Logic project comes in.
Plastic Logic's transistors are already used on flexible substrates and electrowetting displays do not have the cell height dependency that defeats many attempts to make flexible LCDs.
E-Ink displays are extremely easy to read and low power - they currently dominate e-books - but are slow and are extremely unlikely to be suitable for video so access to faster low power technology with colour potential will broaden Plastic Logic's available market.