| 摘要 |
A luminous trace of varying length is produced upon a first non-centralized portion of the screen of a cathode ray tube used in a phototypesetter for generating characters, and is precisely imaged upon positions of a photosensitive medium. The concentration of the electron beam to generate the required trace eventually burns out the phosphor. The life of the tube is greatly extended by thereafter rotating it to position a second non-centralized portion of the screen at the optical projection axis, and so on, and thus, the cathode ray tube life is greatly extended. |
