| 摘要 |
The process is utilised in a digitizer comprising a plurality of grid conductors (7) which are parallel and spaced and are embedded beneath a support surface, and a winding (15) for a movable pen excited by an amplifier and inducing alternating current signals in the grid conductors. The conductors (7) are scanned from a reference point towards the winding until such time as there is individually identified a first conductor exhibiting an induced signal which is phase shifted with respect to the signal collected on the conductor which precedes it. The conductors (7) are then scanned afresh from a second conductor, situated to one side of the winding (15) and at a distance of 5.08 cm from the first conductor, to this first conductor, until such time as a waveform which is rectified and integrated (133) resulting from the scanning operation undergoes a change of polarity (137). A first number in digital form, which is a function of the time required for this second scanning, and held in a pen position counter, is then stored in a microprocessor device. The polarity of the signal which drives the winding of the pen is then inverted. The conductors (7) are then scanned afresh towards the first conductor, starting from a third conductor situated to the opposite side of the winding and at a distance of 5.08 cm from the first conductor. This scanning is terminated when a waveform which is rectified and integrated which results from the scanning undergoes a change of polarity. A second number in digital form, which is a function of the time required for this third scanning and held in the pen position counter, is subjected to the averaging operation with the first number in digital form from the microprocessor device in order to supply a number which is interpolated and precise, which represents the position of the winding of the pen. <IMAGE>
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