| 摘要 |
The device comprises two electrical conductors (1, 2) which extend perpendicullar to the direction of movement of a sheet (3) near the free end of the sheet, which can be unrolled and rolled up on a substrate (5). Permanent magnets (4, 5, 6, 7) are arranged on either side of the substrate (S) near its two longitudinal edges. These magnets produce magnetic fields perpendicular to the plane of the substrate (S) such that, when a current passes in one or other direction through the conductors, forces are exerted on them in the direction of the double arrow (F) and develop torques which cause the sheet (3) to roll or unroll. The device can be used as a shutter for a camera lens by fixing a rolled sheet along the two opposite edges of the substrate (S). |
