| 摘要 |
PURPOSE:To reduce the shape distortion of a beam spot obtained on a screen by providing an auxiliary electrode in a focusing electrode to applying the dynamic focus voltage. CONSTITUTION:Cathode 4 mounted in cup-shaped control electrode 3 froms an electron emission part, and cup-shaped accelerating electrode 5, focusing electrode 6 and anode 7 are successively arranged coaxially in front of electrode 3, and flat ring-shaped auxiliary electrode 8 is arranged in electrode 6 and is insulated from other electrodes. Electrode 8 has oblong square-shaped aperture 9 to pass electron beam. Three electron guns equipped with this electrode structure are arranged on the horizontal axis, thereby constituting a three-electron gun. When the focusing voltage and the parabolic-waveform dynamic focus voltage are applied to electrode 6 and electrode 8 respectively at a picture tube operating time, beam spots which appear at the center and the circumference on the screen have a shape approximating a perfect circle. |
