Touch input apparatus including annular open or closed loop ground plate, with or without slits, positioned around a magnetic core, for decreasing eddy loss

An input apparatus comprising:

• a conductivity tip;
• a coil electrically connected to the conductivity tip;
• and
• a ground plate electrically connected to the coil, and forming an open loop in a circumference direction of the coil,
• wherein the open loop includes an open portion that extends from one side of the ground plate to another side of the ground plate,
• wherein the ground plate further includes at least one slit that extends into a side of the ground plate, and
• wherein the open portion of the ground plate is different than the at least one slit in the ground plate,
• wherein the conductivity tip contacts with a surface of a touch panel outputting an alternating current (AC) power with at least one electrode, a capacitor is formed between the conductivity tip and the at least one electrode by the contact, and the AC power is transferred through the capacitor to the coil, and
• wherein the coil transmits an electromagnetic signal to an antenna of the touch panel according to an electromagnetic induction.