Patent ID: 8659580
Filing Date: 2014-02-25
Classification: G06F

Abstract:
1. A new electromagnetic pen without a battery, comprising: a body; a core disposed in said body wherein one end of said core protrudes and exposes from a front part of said body for writing, drawing or selecting an object on a tablet; a first coil wound around a first permeability material and disposed on said core for emitting electromagnetic signals to the tablet; an oscillator circuit wherein said oscillator circuit comprises: said first coil; an adjusting circuit for adjusting the frequency of the electromagnetic signal emitted from said first coil to get the desired frequency precisely wherein said adjusting circuit and said first coil are in parallel and said adjusting circuit is formed by several capacitors and a variable capacitor wherein they are in parallel; and a transistor circuit for forming a feedback oscillation with said first coil wherein said adjusting circuit is disposed between said first coil and said transistor circuit and said transistor circuit is formed by a transistor, several capacitors, and several resistors wherein they are series-parallel connection; a second coil wound around a second permeability material wherein said second coil resonates with a electromagnetic energy emitted from the tablet for receiving the electromagnetic energy and then the electromagnetic energy is transmitted to said first coil for providing power to said first coil to emit electromagnetic signals; and a switch disposed on said body for controlling the frequency of the electromagnetic signal emitted from said first coil.