| 摘要 |
PURPOSE:To produce a good focus characteristic over the entire surface of the screen by causing the deflecting magnetic field of a deflecting yoke to have an error the amount of which is the same as the amount of a change in convergence caused by dynamic focusing and the direction of which is reverse to that of said error. CONSTITUTION:A deflecting magentic field distributes along the tube axis and extends from the electron gun to the screen. It consists of a horizontally deflecting magnetic field (a) and a vertically deflecting magnetic field (b). The shape of the field (a) changes from barrel-form to pincushion-form as indicated by curve 41 and that of the field (b) is barrel-form as indicated by curve 42. The intensity of the field (a) is smaller than that of a conventional horizontally deflecting magnetic field (indicated by curve 44) both for the barrel-form area and the pincushion-form area. And, the intensity of the field (b) is smaller than that of a conventional vertically deflecting magnetic field (indicated by curve 44). The shapes and the sizes of the horizontal and the vertical deflecting magnetic fields are adjusted so that an error the amount of which is the same as the amount of a change in convergence caused by dynamic focusiong is produced when focus voltage is constant and this error is canceled during focusing. |
