| 摘要 |
An electronic whiteboard uses parallel copper traces of a printed circuit board (PCB) as the detecting surface. Each copper trace is terminated with a capacitor and resistor. The combination enables the picking up of radio frequency emitted from the transmitter pen. With the proper gain stage, the detected signal can identify the proximity of the writing pen. The fundamental or harmonic frequencies of the transmitter pen may determine the colour of the pen. |
