| 摘要 |
PURPOSE:To make an electron gun shorter and compact without deteriorating the features of a BPF lens by a method wherein a variable low voltage, a high voltage, and an intermediate voltage are applied to third and fifth grids, a seventh grid, and fourth and sixth grids, respectively. CONSTITUTION:A cathode K and first-seventh grids G1-G7 are provided, the second G2 being connected to a 450V supply, the third G3 and fifth G5 to a 600V variable supply in common, the fourth G4 and sixth G6 to a 9KV intermediate supply in common, and the seventh G7 to a 27.5KV. Of these second G2-fourth G4, a prefocus lens l1 is formed, whereas a UPF lens l2 is formed of the fourth G4-sixth G6, and a BPF lens l3 is formed of the sixth G6-seventh G7. By making low potential variable with this arrangement, the range of making the focus adjustment variable is enlarged, so that the length of an electron gun can be shortened without deteriorating the features of the BPF lens. |
