Graphic tablet hardware is according the principle of electromagnetic induction, during cursor positing and movement, it is completely done by electromagnetic induction.
Inside the board of graphic tablet, there is a circuit board, which is also called Antenna board. There is copper line with the balanced horizontal and vertical alignment. Cut the tablet into a number of squares, a balance crisscross magnetic field above the board.
When the nib moves on the tablet, the magnetic field cut to generate an electrical signal.
With multi-point positioning, the tablet chip can accurately determine position of the pen tip of tablet.
Therefore, the pen can move without touching the tablet during the movement of tablet cursor.
The induction height is generally 15 mm. The principle of active wireless tablet is different with the passive wireless.
The pen with battery can release a certain magnetic field, while the pen without battery is reflected by magnetic field generated by the digital tablet.
The pressure is generated by the pressure resistor in the pen, and the pressure is fed back to the tablet by magnetic field signal.