ELECTRIC PEN AND TABLET FOR A DIGITIZING DEVICE

摘要

The present invention relates to an electric pen and tablet for a digitizing device, used together as a device for computer input, which safely and surely transmit and receive a button touch signal and a writing pressure signal from a cordless electric pen without batteries through a simple circuit configuration. The electric pen for a digitizing device according to one feature of the present invention includes an LC resonant circuit, an electric pen driving unit, and a load modulation switch. The LC resonant circuit operates after receiving a continuous wave from a transmitting/receiving coil of a tablet having a plurality of transmitting/receiving coils laid to mutually intersect each other at a predetermined interval in the horizontal and vertical directions. The LC resonant circuit receives the continuous wave from the transmitting/receiving coil through electromagnetic induction coupling. The driving unit for the electric pen includes at least one button switch and a writing pressure sensor, and outputs a pulse signal for load modulation control at respectively different timings after the LC resonant circuit receives the continuous wave according to the switch type of the touched button and the magnitude of the writing pressure sensed by the writing pressure sensor. The load modulation switch is turned on in response to the pulse signal for load modulation control to short-circuit the LC resonant circuit.