| 摘要 |
<p>PURPOSE:To obtain an induced voltage in a proper level even if the distance between a position detecting part and a position indicator is long, by receiving a radio wave transmitted from a tuning circuit and detecting and amplifying the induced voltage to calculate the indicated position of the position indicator. CONSTITUTION:A processor 7 monitors output values of LPFs 609 and 610 to detect turning-on/off of a switch 411. Detected state information of turning-on/off of the switch 411 is used as information which designates the value to be actually inputted out of coordinate values of positions designated by a pen 4. Even if, at first, the distance between a position detecting part 1 and the pen 4 is long in the range of a prescribed distance (2-3cm), a variable gain amplifier 603 is so controlled that a maximum voltage value of the induced voltage obtained from the loop coil of the position detecting part 1 is within a prescribed range. Consequently, the coordinate value of the position indicated by the pen 4 is accurately obtained to discriminate turning-on/off of the switch 411 even if a book or the like is placed on the input face of the detecting part 1 and coordinates are inputted from above the book or the like by the pen 4.</p> |
