| 摘要 |
<p>PURPOSE:To reduce the power consumption of an electromagnet in a driving stage by energizing a second coil, rising a magnetic field by the coil, and then energizing a first coil to hold a predetermined magnetic field. CONSTITUTION:A second switch 2b is first introduced so as to generate a magnetic field to allow a current to flow to a second coil 1b. The inductance of the coil 1b is smaller than that of a first coil 1a and its DC resistance is small. Thus. when a voltage +V is applied, a current abruptly flows. Then, a magnetic field generated at an electromagnet 1 abruptly rises. After a predetermined time or after the fact that the magnetic field generated by the coil 1b or the current flowing to the coil becomes a predetermined level is detected, a first switch 2b is closed, and the switch 2b is opened to allow a current to flow to the coil 1a, thereby holding the magnetic field generated from the electromagnet 1. The number of turns of the coils 1a, 1b, the DC resistance and the voltage +V are set according to the intensity of the magnetic field to be held.</p> |
