| 摘要 |
PURPOSE:To improve the color shading and also to increase the margin of a white balance to a focus magnetic field change by giving a potential difference between a horizontal deflection electrode DC potential and a vertical deflection electrode DC potential in an image pickup tube of electromagnetic focusing and electrostatic deflection type, and making the potential difference changeable. CONSTITUTION:A voltage divider giving a potential difference between a horizontal deflection electrode DC potential and a vertical deflection electrode DC potential is provided by adding resistors 18, 19, 20 and a variable resistor 21, the horizontal deflection electrode DC potential is fed from a point A, the vertical deflection electrode DC potential is fed from a point B and the variable resistor 21 is adjusted so as to provide a potential difference to the potentials supplied to the deflection electrode from the points A, B and vary the potential difference. In taking focus current values of red and blue signals when the center modulation of the signals takes a maximum value as IF1 and IF2 respectively and their difference as DELTAf, the state of DELTAIf=0 is attained, that is, the center modulation characteristic of the red and blue signals is made coincident thereby improving the color shading and also increasing the margin of the white balance to the focus current change, by adjusting the potential difference of the points A and B with the variable resistor 21. |
