MicroOLED only drives the pixels that need a refresh

November 04, 2016 // By Julien Happich
Researchers from the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology (FEP) in Dresden have developed a near-eye OLED display for head-mount wearables that can drastically reduce overall system power consumption.

When built into smart glasses to display real-time data (such as heart rate, GPS information, distances etc…) the new OLED only refreshes the pixels that need an update while retaining the overall state of whatever static background pixels. In some cases, that may be only the last digits of evolving data, hence refreshing only a fraction of the whole display. In another example, you could only refresh the pixels where the action takes place in a video, while static background would remain unchanged.

The research center says that for video applications, the new approach was able to reduce power consumption from 200mW (typical of microdisplays) to between 2 and 3mW, two orders of magnitude.

"While in traditional microdisplays, the whole image is refreshed line by line, we've redesigned the control circuitry in order to be able to address every single pixel individually, like in a memory with address lines and columns", explained Philipp Wartenberg, IC Design Engineer and Project Manager in the Department of IC & System Design at Fraunhofer FEP, adding that the AMOLED is fabricated onto a CMOS electronic backplane. The display pixels are equipped with static memory and arranged in a freely addressable matrix, explains Fraunhofer FEP in its brochure.

"We've analyzed different applications, and we thought it would be nice to build a display onto which all the pixels could be addressed individually. We can achieve significant energy savings by doing that, even more so in the whole electronic system than just at the display level" Wartenberg told eeNews Europe.

In some applications, you know the region where the pixels are changing, where you'll get status information, and you can optimize the electronics for that, but in the case of live video streams, the application could use a compression algorithm to modify and recalculate the video data so it would only refresh the pixels that need it. This could be done on a smartphone or even in the cloud upon the app's request.