| 摘要 |
<p>PURPOSE:To allow the detection of both AC and DC currents by disposing a liquid crystal cell in the air gap of an annular magnetic circuit and disposing optical fibers for inputting and outputting optical signal oppositely to the liquid crystal cell. CONSTITUTION:Current to be measured flows through a wire 6 and a liquid crystal current sensor 1 is disposed closely thereto. The sensor 1 comprises an annular magnetic circuit 2 having an air gap 8 made of a ferromagnetic material, a liquid crystal cell 3 disposed in the air gap 8, and optical fibers 4, 5 for inputting and outputting optical signal. Current flowing through the wire 6 induces a magnetic field which 15 concentrated to the magnetic circuit 2 and amplified before it is applied to the liquid crystal cell 3 in the air gap. Liquid crystal molecules in the cell 3 are deflected by the magnetic field being applied to cause variation in the retardation of light thus varying the light transmittance of the cell 3. Light transmittance of the sensor 1 varies depending on the current which is thereby detected by means of the optical fibers 4, 5.</p> |
