German researchers from the Fraunhofer Institute explained that data processing chewed through the batteries of many display spectacles, which show both a projected image and the real world, in under an hour.
Another problem is the warmth generated by the microprocessors, which can lead to the frames of the spectacles heating up – a major issue for anything touching skin.
To create a smooth rather than a flickering display, 60 images a second need to be played on the lens surface, eating up a lot of the stored electricity.
The researchers, including project manager Philipp Wartenberg, noted that for a video image, there were areas that changed, such as a person walking, and areas that did not – such as the background room.
They therefore built a circuit that only “lets through” the portion of the data where a part of the display image was changing, Mr Wartenberg explained, adding: “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.”
The pixels in the display therefore light up until the control chip tells them to stop. Using this technique, the system requires two to three milliwatts of power, compared to the 200 milliwatts required by other smart spectacles displays, he said.
The radio-linked prototype will be presented at an electronics trade show (8–11 November) in Munich.