| 摘要 |
[Para 1] An electronic whiteboard uses parallel copper traces of a printed circuit board as the detecting surface. Each copper trace is terminated with a capacitor and resistor. The combination enables the picking up of radio frequency from the transmitter pen. With proper gain stage, the detected signal can identify the proximity of the writing pen. Since the detecting surface is made only of a printed circuit board, all the interfacing components can also be stuffed onto the same PCB. It dramatically simplifies the production of the electronic whiteboard without the intervention of human alignments, and the material cost will be reduced significantly. The idea was filed under the same name of the inventor, Lau Chun To, in China on 25th September 2007 and the China patent no. ZL 2007 2 0172112.0 was granted on 9th July 2008.
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