| 摘要 |
<p>The invention relates to electronic picture-taking tubes.
<??>Particularly in picture-taking tubes whose electron beam, scanning a photosensitive target, is oriented by an electrostatic deflection system, the appearance of ghost images in the video output signal from the tube has been observed. These images are apparently due to a return beam coming back from the target (12) and striking the accelerating electrode (22) of the electron gun (14).
<??>It is proposed, in order to suppress these ghost images, to mask the accelerating electrode with a masking shield (38) brought, in principle, to the same potential as the electrode, this shield being characterised by its rounded edges, convex towards the target; it is drilled with a central aperture (40) also provided with rounded edges.
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