| 摘要 |
The shadow mask of a color picture tube is formed by etching a blank to provide a field of apertures individually having a large diameter portion and a coaxially aligned, small diameter portion attached to the former by a thin wall section. In screening a tube which is to utilize such a shadow mask for color selection, the phosphor materials are deposited on the screen in a photographic process involving the exposure of a layer of photosensitive material by actinic energy directed through the small diameter portions of the mask apertures. After screening has been accomplished, the thin wall sections are etched away, leaving the mask with apertures of large diameter, larger than the phosphor deposits in the screen.
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