| 摘要 |
PURPOSE:To enlarge the aperture of a main lens as well as to improve the assembling accuracy of an electron gun and make improvements in the focusing characteristic, by setting an electron beam passing hole of a main lens forming electrode down to each of specified deformed holes, while forming a special groove on the bottom surface of at least one side of electrode. CONSTITUTION:Two sets of elliptical thick platelike electrodes, which sets up three electron beam passing holes in-line form in a long diametrical direction, are made to be oppositely set up with the bottom side at regular intervals, and a main lens field forming electrode constituting a main lens electric field is installed in position between these opposite electrodes. Electron beam passing holes 50A-50C at both sides of an elliptical thick platelike electrode 50 of an electron gun for a color picture tube like this is set down to each of connected deformed holes setting the outer direction down to a semicircle while the inner direction to a semioval making the short diametrical direction of an oval thick plate a long diameter, respectively. In addition, a peripheral edge part of the oval thick plate is left behind at the short diametral part of these electron beam passing holes where each of electron beam passing holes 50A-50C adjoins whereby a groove 50D is formed on the bottom surface of at least one side of these oval thick platelike electrodes 50 so as to cause an interval between opposite electrodes to become widened.
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