| 摘要 |
PURPOSE:To obtain a beam spot of truely circular form by making the periphery of a yoke to have a non-circular shape like the other electrodes, and making the side beam passing holes of the yoke to have an oval shape, which has a long diameter extending in a horizontal direction and has short diameter ends extending along the wall of the neck tube. CONSTITUTION:A cathode 2, a first and a second grid 3 and 4, and a magnetic yoke 50 are placed in a bulb 1, and an annular permanent magnet 8 is placed outside the bulb 1, thereby an electromagnetic focusing cathode-ray tube being constituted. The first and the second grids 3 and 4 and the magnetic yoke 50 have non-circular shapes since they are formed by cutting circular shapes. The parts corresponding to the cut parts of the yoke 50 are supported with supporting rods 90. Then, side beam passing holes 51S1 and 51S2 provided on the yoke 50 is made to have an oval shape, the long diameter of which extends in a horizontal direction and the short diameter ends of which extend in the direction along the neck tube. Consequently, the aberration caused due to the non-circular form of the yoke 50 can be corrected, and the beam can be made to have a truely circular shape. |
