Importance

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Abstract

Disclosed is a coordinates input system having a tablet constituting a coordinates input portion, a position designating device such as a stylus pen, and a position detection circuit adapted to drive said tablet and detect a position at which coordinates are input by said position designating device. The system comprises: an antenna coil disposed around a coordinates input range of said tablet; and a tuning circuit disposed in said position designating device and including a coil and a capacitor, wherein radio waves are generated by said antenna coil by application of an AC signal of a predetermined frequency thereto, and the status of said tuning circuit is discriminated by a signal of said antenna coil at the time when the transmission of said radio waves is suspended, thereby detecting the status of said position designating device. Hence, this coordinates input system is capable of detecting the status of the position designating device without connecting the position designating device and other circuits by means of a cord and without providing the position designating device with a conventionally employed complicated signal generating circuit, a battery, and the like.

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First Claim