| 摘要 |
PURPOSE:To obtain a focusing magnet which is of a small-size and lightweight and has little outside leakage magnetic field by setting the ratio of the outer diameter of a yoke plate to the outer diameter of a permanent magnet within a specific range. CONSTITUTION:The yoke plates 1 and 2 each of which has the passing-through hole for the neck 5 of a cathode-ray tube at the cener and has the outer diameter C1 smaller than the outer diameter D2 of a permanent magnet are fixed on the same axis to the center of the passing-through hole part of the neck 5 of the magnet 3 at both ends of a ring-shaped permanent magnet 3. It is necessary for the center magnetic field X to be within a prescribed range obtained from the outer diamter D1 of the yoke plates 1 and 2 and the outer diameter D2 of the permanent magnet 3, and for this purpose, the ratio of D1/D2 is set within 0.8-0.99. Thus, a focusing magnet which is of a small-size and lightweight and has little outside leakage magnetic field can be obtained. |
