| 摘要 |
<p>PURPOSE:To accurately detect the vertical distance from a magnetic label despite the increase of this distance by using two air core coils to form a detecting coil and connecting these two coils to each other so as to eliminate the electromotive force. CONSTITUTION:The right and left magnetic poles 8a and 8b of a bar electromagnet 8 are held between 1st and 2nd right air core coils 12 and 14 and 1st and 2nd left air core coils 14 and 18. These 1st and 2nd air core coils have the same winding direction, the same number of turns and the same diameter and are connected in series. Thus the directions of the magnetic fluxes passing through the 1st and 2nd air core coils are adverse to each other. As a result, the electromotive forces are eliminated to each other between the 1st and 2nd air core coils. Therefore the magnetic line of force generated from the magnet 8 is deflected when a magnetic gets close to the magnet 8. Thus the voltages Vr and Vl are produced from the right and left detecting coils, and the presence of the magnetic mark is detected.</p> |
