| 摘要 |
PURPOSE:To detect exactly a position by placing a read range outside detecting sense line in the circumference of a scanning circuit and an amplifying filter circuit, detecting a calling-on signal induced by its line, and inhibiting a detection of a position of an energizing coil. CONSTITUTION:A co-ordinate reader is provided with a tablet 11 formed by laying a lot of sensor lines on a plate, scanning circuits 12a, 12b for selecting successively its sensor lines, an amplifying filter circuit 13 for amplifying and filtering a signal from its circuits 12a, 12b, an energizing coil for generating an alternating field, etc. Also, read range outside detecting sense lines 16a, 16b and 16c are laid in the circumference of the circuits 12a, 12b and the circuit 13, and a detecting circuit 17 is connected to the lines 16a, 16b and 16c. In this state, a signal of the outside of the read range, which is induced by the lines 16a, 16b and 16c is detected by the circuit 17 and applied to a switching circuit 18, and a signal for inhibiting a detection of a position of the energizing coil is supplied to a controlling circuit 14, by which a detection of an erroneous position is prevented. |
