Basic principle
There are large number of infrared senders and receivers placed around all the four sides of whiteboard closely, which comprise a dense matrix vertically and horizontally. When something touches some point of the whiteboard, which blocks the corresponding vertical and horizontal infrared rays, the X/Y coordinate is decided. Then the computer would easily know at where you give your command.

Technical Advantage
1. Exact position, higher precision.
2. Fast response.
3. Unnecessary for special pen. Any nontransparent thing is available to operate on the whiteboard, such as your finger, pointer etc.. Much easier and more convenient writing.
4. Against scratch. And even scratch occurs on the whiteboard, the normal use would not be affected.
5. Products' using life is pretty long.
6. Easy way for power supply, just by USB connection.

Disadvantage
1. Cost would be higher, and it would rise markedly by the increase of whiteboard's size.
2. It may be affected by strong infrared ray.
3. It can't support the right button function directly.