Patent ID: 8692814

Claim:
An electromagnetic pointer, said electromagnetic pointer comprising: a metal rod; a circuit board having at least one capacitor thereon, two contacts and one trigger point at one side of the circuit board, wherein the trigger point is between the contacts and is not connected to the contacts; a ferrite core with a coil winding the ferrite core to form an inductor, the coil electrically connecting to the circuit board to form a resonance circuit, the metal rod penetrating trough the ferrite core and being moveable through the ferrite core; a spring, the spring contacting the contacts, the spring is configured to be able to be pushed by the metal rod to contact the trigger point so as to connect the contacts and the trigger point through the spring to change electric properties of the resonance circuit and complete a circuit on the circuit board; and a pen holder assembly accommodating the metal rod, the circuit board, the ferrite core with the coil, and the trigger device.