Fraunhofer Institute Creates OLED-based Energy Saving Data Glasses

Data glasses are designed to mirror information directly to the eye without interfering with the wearer‘s vision. While playing back images, the electronics tend to consume a great amount of electricity causing the battery to run down quickly. Fraunhofer researchers claim to have developed an energy saving data glasses display that can decrease the power consumption to a fraction of conventional data glasses. Fraunhofer will present the new microdisplay at the electronica trade fair in Munich from November 08-11, 2016.

Engineers from the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP in Dresden have created an energy saving data glasses display that is also exceptionally bright.

Data glasses employ a radio link in the frame of the glasses that brings information or images directly to the eye via a tiny display. The big advantage which has not caught on widely with the data glasses is that the wearer’s hands are free, unlike smartphones that need to be held in one’s hand.

Mechanics and other technical professionals may benefit from such hands-free operation. They can use data glasses to see construction plans and assembly instructions while keeping their hands on the tools. Fraunhofer says that athletes including mountain bikers are increasingly using data glasses to follow the projected navigation arrows as they travel. The cyclists can keep their hands on their handlebars. Whereas, the smartphone with the GPS remains in a pocket.

One of the main drawbacks of micro-displays is that they use up a lot of battery power because creating the video images requires the processing of lots of data. The charge for most data glasses lasts just an hour or even less. Also, the microprocessors get hot very quickly and warm up the frame of the glasses, which is unpleasant for wearers.

The scientists apply the OLEDs to a silicon semiconductor which controls the individual pixels. The FEP has also integrated a camera function into the chip enabling the OLED microdisplays to not only emit light but to perceive the surroundings. A small light-sensitive photodiode is located in each pixel. The camera function helps determine, for example, the direction in which the wearer looks. However, like other microdisplay technologies, these displays consume a lot of energy to process all the image data.

Reduced data stream

A video display requires the playing of 60 images per second to avoid flickering. The control electronics and the chip must process large amounts of data very quickly, which consumes a lot of electricity. Processing this much data tends to heat up the chip and the control electronics. Project manager Philipp Wartenberg and his colleagues at the FEP claim to have found a way to reduce the smartphone data stream.

“We now control the chip so that the entire video image is not constantly renewed, rather only that part of the display in which something changes.” For example, when an actor runs through a room in a movie, only his position changes, not the background. In applications such as a navigation system for cyclists, in which only arrows or meter information is displayed, it is unnecessary to constantly renew the whole picture, said Wartenberg. “To put it simply, we have now adapted the circuit so that it only lets through that portion of the data stream which changes.”

Redesigned semiconductors and control electronics

Wartenberg and his colleagues had to redesign the chip and the control electronics in large parts to create the prototype data glasses that the experts are now presenting at the electronica trade fair in Munich.
While ordinary data glasses require a light output of 200 milliwatts, the FEP display needs only two to three milliwatts- just one hundredth of the original amount. Nevertheless, the OLED technology enables the display to be very bright.

The pixels of modern displays, which are designed for rapid, repeated images, normally stop lighting up after a relatively short time causing the still areas of the display to soon appear black. The development by the FEP controls the pixels so that they don’t have to relight as often and therefore last longer.
Wartenberg can imagine athletes in the future such as joggers could use the display to continually check their heart rate without having to look at a jiggling smart phone.

Luxeon Color