Patent ID: 6744426
Filing Date: 2004-06-01
Classification: G06F

Abstract:
A coordinate reading system, comprisinga coordinate input device, the coordinate input device including: a coil generating an alternating magnetic field; an angle-modulation portion that modulates the alternating magnetic field in an angle modulation to thereby successively change an angle state of the alternating magnetic field into a plurality of different states in a plurality of successive time durations, while setting a length of at least one time duration to a value corresponding to information of the coordinate input device, the angle state being maintained, during each time duration, as being fixed to a corresponding state and changing from the corresponding state into another state at a timing between the each time duration and its next time duration; and a coordinating reading device, the coordinate reading device including: a main body having a surface defining a coordinate of the coordinate input device; a plurality of wires provided to the main body, each wire generating, upon receipt of the modulated alternating magnetic field, an electric signal whose amplitude corresponds to the position of the coordinate input device and whose angle state corresponds to the angle state of the received alternating magnetic field; a coordinate detection unit that calculates the coordinate of a position of the coordinate input device based on the amplitude of the generated electric signal; and an information detection unit that detects the length of the at least one time duration by detecting timings when the angle state of the electric signal changes, thereby determining the information of the coordinate input device.