HD Series of Interactive Whiteboard IEBOARD use electromagnetic induction technology. It is used to emit electromagnetic wave of a pen and the board surface is composed by the receiving coil membrane in both directions by the horizontal and vertical array. The membrane size is the same with the display area. Electromagnetic pen  intermittently emits electromagnetic wave, when the pen is near the membrane of the receiving coil, the coil will be induced to the electromagnetic launchers. The nearest coil groups to the pen induce the most powerful electromotive force. According to the horizontal direction and vertical direction of the force sensor, the pens location of X, Y coordinates can be found by calculating.