Apparatus for assembling and inspecting electron gun of cathode ray tube

An apparatus for assembling and inspecting an electron gun of a cathode ray tube,

• said electron gun comprising:
• a cathode;
• a G1 electrode that derives electrons from said cathode;
• a G2 electrode;
• a G3 electrode that accelerates emitted electrons toward a screen as a display surface, said G1 thorough G3 electrodes respectively having electron-beam-transmission holes;
• and
• a Gm electrode provided between said G2 and G3 electrodes, and having an electron-beam-transmission hole that is smaller than said electron-beam-transmission holes of said G1 through G3 electrodes, inner diameters D1, D2 and Dm of said electron-beam-transmission holes of said G1, G2 and Gm electrodes satisfying the relationship:
• D1≧D2>Dm, said apparatus comprising:
• a mandrel having an outer diameter that is larger than said inner diameter of said electron-beam-transmission hole of said Gm electrode, said mandrel abutting against a part around said electron-beam-transmission hole of said Gm electrode from said G3 electrode side, thereby to seal said electron-beam -transmission hole of said Gm electrode;
• and
• a measuring nozzle having a tip that can be inserted through said electron-beam-transmission holes of said G1 and G2 electrodes from said G1 electrode side, said measuring nozzle blowing air toward said mandrel, for measuring a clearance between said G2 and Gm electrodes according to the change in pressure of blown air.