| 摘要 |
PURPOSE:To ensure the effective elimination of the after-image by repeating alternately the field for reading the video signal and the field for erasion of the after- image. CONSTITUTION:In the field for reading of the image, constant circuits 14 and 17 are connected to electron beam focusing circuit 13 and bias circuit 16 via the function of selectors 15 and 18 so that the diameter of the electron beam may be stopped down into the small value on photoelectric screen 8. In the next field, constant circuit 19 is connected in switching to circuit 13 so that a necessary size may be secured for the electron beam diameter on screen 8. At the same time, constant circuit 20 is connected to circuit 16 selectively so as to obtain a sufficient amount of electron beam for discharge of the residual charge. The selective switching is carried out in the electronic way for the constant circuits with every field. |
