| 摘要 |
<p>PURPOSE: To obtain an accurate proximity sensor that has a wide and adjustable detection range and where temperature influence cannot be sensitive to electrical and magnetic interference fields, by providing a transmitter for selecting frequency at the electronic circuit of each coil. CONSTITUTION: A measurement coil L1 and a reference coil L2 are provided at each side of a symmetrical plane 10 that passes through a sensor housing. The piece of a magnetic material for surrounding the two coils L1 and L2 is formed by a same homogeneous material for forming a block, and a shielding ring 4 for shielding a magnetic field is provided in a magnetic field that is generated by the both coils L1 and L2 to suppress mutual crosstalk. Then, the electronic circuit of the coils L1 and L2 has a separate synchronization detector with an individual transmitter for frequency selective measurement, and the influence in the characteristic change of a magnetic material and the measurement coil L1 at a detection distance are electronically compensated, thus obtaining an accurate proximity sensor that has a wide detection range and cannot be sensitive to the influence of temperature and electrical and magnetic interference fields.</p> |
