| 摘要 |
<p>RCA 73,250 The gun, for use in a television picture tube, comprises a cathode, an apertured control grid, and an apertured screen grid aligned in the order named. The screen grid aperture comprises a rectangular slot portion facing the control grid and a circular portion facing away from the control grid. The slot portion of the aperture, which has a width 2-to-5 times its depth, creates an astiomatic field that produces underconvergence of the electron beam in the vertical plane only, whereby to avoid and/or compensate for vertical flare distortion of the beam spot at off-center positions on the image screen.</p> |
