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LOMID - Large cost-effective OLED microdisplays and their applications

Periodic Reporting for period 2 - LOMID (LOMID - Large cost-effective OLED microdisplays and their applications)

Berichtszeitraum: 2016-07-01 bis 2018-06-30

The LOMID project was a response to the European Commission's H2020 ICT3-2014 call for "Advanced Thin Organic and Large Area Electronics". The project sought principally to develop larger, higher resolution full-colour microdisplay chips than were on the market in order to address future needs, in particular an anticipated demand for information rich head-mounted displays with a wide field of view, driven by the increased use of virtual reality technologies. To complement the new microdisplay chips, and to show off the wide field of view and immersive experience that the new larger high resolution displays enable, the project has also developed a new approach to optical design that permits VR headsets to be much more comfortable (by virtue of being lighter and more compact). Lack of comfort has been one of the issues slowing the adoption of VR technologies for professional use (i.e. up to 8 hours per day). Another issue slowing the acceptance of VR has been the susceptibility of some users to motion sickness. The project addressed this by ensuring that the display chips, despite the large number of pixels, have a high frame rate which helps to reduce some causes of motion sickness (by reducing the mismatch between head motion and the VR image).
Comfortable head-mounted displays and a wide field of view are also very important for visual prosthetics to be used in the near future by people with severe visual impairment (often legally blind). Part of the LOMID project's work was to test the new displays in such visual prosthetics. These tests have been positive, and we expect the technology to be licensed rapidly by companies working in this area, thus soon improving the quality of life for up to 2 million people in Europe with certain types of severely impaired vision.

The project succeeded fully in meeting its technical objectives, although the considerable technical challenges did require a six-month prolongation of the project. We have produced 1" WUXGA (1920 x 1200) colour OLED/CMOS displays with high brightness, excellent contrast and high framerate that represent the state-of-the art for OLED/CMOS microdisplay technology. Customer interest is substantial, and commercial production is expected to begin in 2019.
Our demonstration VR headset uses two such microdisplays per eye with multichannel freeform optical components to combine a wide field of view with excellent resolution – close to the limit of the human eye, and so with no visible 'screen-door' effect between pixels, whatever the texture viewed. Despite this performance leap, the headsets from the project are half the weight of conventional approaches, and substantially less bulky.
Another technological advance made within the LOMID project has been to show that it is possible to thin and then to bend the microdisplays to conform to a curved surface. The ability to manufacture curved microdisplays will lead in the future to even more compact optical designs for near-eye displays, such as in VR headsets or electronic camera viewfinder. Looking even further into the future, the project has developed new semi-conducting thin-film materials that might be used in the future to make transparent display devices, with possible applications for augmented reality 'smart glasses'. Although we have demonstrated transistors made from these materials, a great deal of further development is needed before commercial application.

We think that the LOMID project has been an excellent example of European cooperation for applied R&D supported by the European Union. The advances that we have made were only made possible by the international cooperation of several partners, and the project's focus on market needs means that commercial exploitation (and job creation) is very likely to happen rather quickly after the end of the project. Nonetheless, the technological and commercial risks of the project were significant and it would have been difficult to obtain financing for the work from banks or investors.

An animation explaining the project can be seen from the link at:

http://www.lomid.eu/project-video-explains-route-to-better-vr-headsets-and-visual-prosthetics/
In the first half of the project, the focus was on fixing the detailed specifications (following a cost-performance trade-off study), followed by the design phase. In order to speed up development and reduce costs, a so-called Test and Qualification Vehicle (TQV) chip was designed – essentially a simplified version of the silicon chip that would be used for the microdisplays. This TQV was used to develop and test new silicon chip (CMOS) fabrication processes required to meet the requirements of the OLED part of the display devices.
A new process for depositing novel transparent materials (amorphous metal oxides) for use as transistors in thin film display devices has been developed, and promising results obtained from the characterisation of these materials in simple components. A new transparent protective coating was developed, a necessary part of the work to show that OLED/CMOS microdisplay chips can be bent and still function.
Attention throughout the project was paid to recycling issues and environmental impact. We have calculated the environmental footprint of the microdisplay chips, and shown that VR headsets can be built in a way that reduces the landfill burden.
The second half of the project was largely devoted to design and implementation of the microdisplay chip. Key technical challenges here were to achieve the performance targets of a resolution of 2300 ppi at a dot count of 9.2 million, combined with a frame frequency up to 120Hz and a very low power consumption of only 150mW, as well as developing the (optional) technology to make them curved. Once the chips were available, they were integrated in the new VR headsets from the project and tested.
The LOMID project has produced microdisplays that are larger, brighter, faster, higher contrast and high pixel density than was possible at the start of the project, and by and large even now. Certainly the combination of the display size with the high performance attributes is unique.
The project has also shown that cutting-edge optical design techniques (multichannel approach with freeform optical components) can greatly increase resolution (up to 24.6 pixels per degree - ppd - to be compared with 14 ppds of the state of the art) and reduce bulk (down to a fourth) and weight (down to a half) for head-mounted displays, without impacting significantly on manufacturability or cost.
The impacts of the project will be
1) increased employment and an improved export balance through the manufacture and sale of microdisplay chips in European factories (albeit possibly with some steps carried out outside Europe)
2) accelerated adoption of VR and AR technology in Europe and worldwide
3) improvement in the quality of life for millions of people with severe visual impairment
LOMID 1" WUXGA OLED/CMOS microdisplay curved with a 45 mm radius. Credit CEA Leti
Improved VR headset from the LOMID project, using two LOMID microdisplays per eye. Credit Limbak
A 1" WUXGA OLED/CMOS microdisplay from the LOMID project. Credit Microoled