EU LOMID VR project creates lightweight microchips & organic LEDs

Microchips and organic LEDs that deliver 4K-like high resolution displays a quarter of the size and half the weight of existing virtual reality (VR) headsets have been developed under a European Union project.

Lighter weight goggles make virtual and augmented reality easier to use by the likes of the emergency services, and not just video game players. Firefighters could use augmented reality goggles to see in low visibility conditions such as smoke-filled rooms. Virtual reality versions of the goggles could be used for training.

On a 2.54-centimetre display, the EU funded microchip has allowed as many pixels to be presented as a high definition (HD) television would in its entire screen. An HD TV picture has 1,920 pixels by 1,080 pixels. This 2.54-cm display is refreshed every eight milliseconds for a 120 Hertz frame rate. This high pixel density has also been achieved with low power consumption, say the researchers.

Limbak and Franhofer will showcase the 25 ppd, 37 mm TTL VR headset developed within the LOMID project at CES 2019.

The OLED part of this new VR display also achieved energy efficiency gains and improvements on its reliability with an expected lifespan greater than 15,000 hours; more than 600 days of continuous use.

This high resolution microdisplay has been achieved with a chip design manufactured using a lithographical process that can produce features as small as 0.35 microns. The microdisplay performance has also been achieved with a unique interface between the OLED and the top metal layer of the microchip’s backplane. The backplane wafer technology is to be produced by German project partner company, XFAB Semiconductor Foundries. The microchip is made on a 200-millimetre wafer.

Limbak, a partner in the EU VR project, has also created microdisplay chips for a wider field of view with a resolution of 4,800 by 1,920 pixels; two and a half times more detailed than existing HD displays. The resolution known as 4K has 3840 x 2160 pixels. Companies are expected to start marketing less goggle-like headsets for augmented reality, at least, this year. One such company is Florida-based Magic Leap and its first product is Magic Leap One.

The coordinator of the EU VR project, called Large OLED MIcroDisplays (LOMID), was Uwe Vogel, director of microdisplays and sensors at the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology, based in Dresden, Germany. He says: “For professional purposes you need to move around so weight and visual comfort are very important, and miniaturisation is key.” A three-year project, LOMID ended on 30 June 2018 and had a budget of 4.1 million euros.

Vogel says that headsets developed under LOMID, “have much higher performance, are smaller, more lightweight and have better resolution than existing virtual reality headsets on the market, but with the same field of view.” The LOMID partner, French company MICROOLED, is going to commercialise the 2.54-centimetre OLED microdisplay chips.

Another key feature is that the microchip’s wafer is sufficiently thin that the subsequent display can be bent by up to a 45millimetre radius. “Typically for microdisplays now on the market the silicon chip backplane containing the circuitry and sockets is rigid,” says Vogel. “What was achieved, mainly by project partner CEA-LETI in Grenoble, France, was to bend the one-inch [2.54-cm] screen microdisplay. This will enable even smaller optics for VR headsets.”

As well as the Fraunhofer Institute, CEA-LETI, X-FAB, MICROOLED and Limbak, the other LOMID partners are the University of Oxford, the University of Leipzig, the French government's Commission for Atomic Energy and Alternative Energy and the companies, Amanuensis and Slyde Watch.