| 摘要 |
<p>An apparatus for sensing the distance between an object (3, 4) of electrically conductive material and a reference point has an electrode (12h, 12v), the tip of which constitutes the said reference point. The electrode is connected via a supply line (15h, 15v) to a high voltage source (14) adapted to generate high voltage pulses to provide an arc (16h, 16v) between said electrode tip and said object (3, 4). The apparatus also has an air-cored measuring coil (17h, 17v) disposed around said supply line (15h, 15v) for sensing the electric field about said supply line and transmitting to a measuring signal sensing circuit (18h-25h, 18v-25v) a measuring signal proportional to said electric field. The measuring signal sensing circuit preferably comprises a comparator unit adapted to compare the measuring signal with a signal corresponding to a predetermined distance between the object (3, 4) and the electrode tip.</p> |
