Virtual reality shows no signs of waning in its popularity, both for businesses and for consumers. One aspect that has hampered greater take-up is the weight and oversized nature of the headset. This will now change through the use of microdisplays, based on organic light-emitting diode (OLED) technology.
Microdisplays are miniaturized display units with screen sizes and resolution in the micro levels. Their small size enables them to be used in a wide variety of applications. The microdisplay for the new generation of virtual reality headsets is formed from two components: a silicon chip to control the pixels, and an OLED, formed of several organic layers monolithically integrated on silicon wafers.
The research into OLED technology has been funded by the European Union’s LOMID project (with LOMID being an acronym for large cost-effective OLED microdisplays and their applications). Part of the funding has been channeled into the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, located in Dresden.
The aim of the Fraunhofer Institute research is to improve image quality and portability, through a reduction in weight, of virtual reality headsets. Weight is addressed with OLED powered headsets because there is no need for a backlight. This also means that manufacturing is more straightforward and there are fewer componets to assemble.
As well as addressing weight, microdisplays provide superior resolution compared with the types of technologies currently available, such as those used in virtual reality headsets aimed at smartphone users. These current devices tend to produce pixelated images, which is a factor of their limited resolution and insufficient pixel density.
In contrast OLED microdisplays are based on organic light-emitting diodes, which are integrated onto a silicon chip and are self-illuminating. This means the OLEDs are energy-efficient and they yield very high contrast ratios in excess of 10,000:1. The researchers have achieved so-termed full HD, which they define as a resolution of 1920 x 1200 pixels. With this, the diagonal screen size is about one inch, and the frame rate is around 120 Hertz. That means 120 images are displayed every second.
OLED devices also have a faster switching speed (within a matter of microseconds). This permits high frame rates which can be used with special modulation processes to improve the perceived image.
Commenting on these developments, Philipp Wartenberg, from Fraunhofer FEP, said in a research brief: “Our goal is to develop a new generation of OLED displays that provide outstanding picture quality and make it possible to produce VR glasses and an eyewear-based support for vision-impaired in a compact format. We aim to achieve that by means of a specially designed OLED microdisplay.”
In terms of applications, in addition to the consumer market, the OLED system can be used in cameras; systems for optical metrology (optical measurements including photometry and radiometry) and identification and the emerging biomedical field of optogenetics (a biological technique which involves the use of light to control cells in living tissue).
The prototype is to be presented in Brussels between December 5 to 7 at the European Forum for Electronic Components and Systems 2017 (EFECS).
