The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has announced that they have developed a particularly energy-saving display that is also very bright. The scientists have many years of experience in the design and manufacture of displays with organic light emitting diodes (OLED).
The OLEDs were fabricated on to a silicon semiconductor backplane that controls individual pixels, to create an OLED microdisplay and along side the OLED engineers integrated a camera function into the silicon. As a result, the OLED microdisplay not only emits light, and perceive the surroundings.
There is also a small light-sensitive photodiode located in each pixel. The camera function, for example, is important in order to determine the direction in which the wearer looks. However, these displays have the same problem as all other displays of data glasses - high energy consumption.
According to the Fraunhofer data glasses mirror information to the eye without interfering with the wearer's vision. However, the battery runs down quickly, because the electronics consume a large amount of power while playing back the images. To solve this the Fraunhofer researchers developed an energy-saving display that reduces the power consumption to a fraction.
Via a small display, data glasses present the eye with information or images which are received using a radio link from the frame of the glasses. The big advantage with data glasses is that the wearer's hands are free - in contrast, a smartphone has to be held in the hand.
Hands free operating are suitable for many users. Data glasses may be interesting for:
- mechanics - they can look at assembly and maintenance service instructions
- athletes - they can look at statistics about the performance in training and in competition
- mountain bikers - they can follow the projected navigation arrows as they travel cross-country
However, despite such benefits, data glasses have not really made a breakthrough yet. The problem is that displays use up a lot of battery power because the video images process lots of data. In most cases, the battery is out of power after an hour. What's more, the microprocessors quickly gets hot. This in turn warms up the frame of the glasses, which is unpleasant for the wearer.
While ordinary data glasses require an output of 200 mW, the Fraunhofer FEP display only uses with 2mW to 3mW a mere one hundredth of the original amount. Nevertheless, it is still bright, thanks to the OLED technology.
Figure: Fraunhofer FEP - Low power OLED microdisplay
In order to reduce the video data stream, the Fraunhofer engineers had to redesign the chip and the control electronics in large parts. The pixels of today’s displays, which are designed for rapid, repeated imaging, normally stop lighting up after a short time. In a model that does not constantly update the entire screen, that cannot be, because the still areas of the display quickly appear black otherwise. The development by the Fraunhofer FEP controls the pixels so that they continue to light.
Project manager Philipp Wartenberg at the Fraunhofer FEP, said, "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." Philipp added, "For example, if 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 metre information is displayed, it is unnecessary in any case to constantly renew the whole picture." Finally saying, "To put it simply, we have now adapted the circuit so that it only lets through that portion of the data stream which changes."