LEDs can be used as light emitters as well as detectors. It is known that like any PN junction, an LED too can be modeled as a capacitor in parallel with a light dependent current source . 'ePaper' exploits this property of LEDs. 'ePaper' is an LED based graphic tablet which allows a user to write or sketch on an inexpensive hand held device. Multiple pages can be saved on the device which can be scrolled through and uploaded to a computer as bitmaps. ePaper is designed to be scalable to any desired dimension.
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