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EETE APR 2014 High-Performance, high reliable Power Supplies 15 W to 12 kW+ adapted to your challenging projects l AC/DC Power Supplies l Rectifiers and Battery Chargers l DC/DC Converters l Sine-Wave Inverters l Phase and Frequency Converters l AC- Input, DC-output UPS systems l Open Frame l Wall mount l 19” Cassettes l DC-input dimmable back-light inverters for LCD displays l Complete Power Systems in 19" and 23" Racks ABSOPULSE Marketing Europe GmbH PoBox 1501 8620 Wetzikon CH Tel. +41 78 896 50 49 Fax +41 44 944 38 44 Write us: See us: Printed Electronics—We Build the Market Exhibition: May 27 – 28, 2014 Conference: May 26 – 28, 2014 Messe München, Germany Neale Cousland / Heliatek GmbH (middle), Karl Knauer KG (below) ©: Organic solar cell: Fraunhofer ISE Holst Centre (above), Top trends. Key innovations. Expert speakers. Register now! 6th International Exhibition and Conference for the Printed Electronics Industry Electronic Engineering Times Europe April 2014 37 LOP14 Anzeige_91x136_EETimes_E.indd 1 01.04.14 11:04 with integrated driving circuits on a single CMOS chip. The active area of the bi-directional microdisplay consists of nested display and image sensor (embedded camera) pixels surrounded by a second image sensor (frame camera) as well as driving and control circuitry – see figure 1. The display and image sensor systems are electrically independent of one another, simply interacting via synchronization signals. A potential issue of such a bi-directional micro-display is optical crosstalk between display and camera. This crosstalk can be suppressed by operating display and camera time-sequentially. The optical system consists of two non-spherical mirrors, a beam splitter and the micro-display – see figure 2. The nonspherical mirrors have a dichroitic coating either reflecting visible light (380-780nm) in the display path or NIR light (780- 1100nm) in the camera path. So the system allows the projection of a virtual image within the natural vision of the environment. The visible light of the OLED passes the beam splitter, gets reflected from the downside non-spherical mirror and is reflected by the bottom side of the beam splitter to the eye. Additionally, the eye is illuminated by two NIR diodes emitting at a wavelength of 850nm. This wavelength leads to an improved contrast between pupil and iris within the captured image. The diodes are placed outside of the optical axis of the camera which creates a dark pupil image. Following these principles, we were able to design a VGA bi-directional OLED micro-display into a binocular interactive see-through head-mounted unit. Here the embedded nested cam acts as an eye-tracking image sensor. The optics measure 45x35mm for a depth of 35mm. Figure 3 shows a captured eye-image, the optics provides a sharp and contrasted projection from the user’s eye to the embedded image sensor. For both eyes, the bi-directional optics are housed in an ergonomic spectacle frame that also integrates driver electronics. The display offers 640x480 pixels (VGA) for each eye, while the image sensor is 128x96 pixels. Transparency for the display is 50%, offering a virtual image at a distance of 750mm for a field of view of 20°x21.6°. Fig. 3: Acquired eye image (left), and the operating see-through HMD (right). Table 1: Comparison of Google Glass and COMEDD data glass features.

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