| 摘要 |
A beam index type cathode ray tube for preventing distortion of index signals due to high frequency noises by protecting an optical detector and an index circuit part from the influence of high frequencies which are generated during the operation of the cathode ray tube, which includes a phosphor screen formed on an inner surface of a panel and having index stripes, an electron gun for emitting electron beams toward the phosphor screen, index light incident part formed on outer peripheral surfaces of respective light receiving windows of a funnel to be provided with the index light signals emitted from the index stripes via the respective light receiving window, optical cables respectively connected to the index optical incident parts for transmitting optical signals, an optical detector converting the optical signals provided from the optical cables to index current signals, an index circuit part synchronizing the index current signals with a color switching signal so as to transmit a precise color switching signal to the electron gun, and a high frequency shut-off part shutting off the optical detector and the index circuit part to block influence of high frequency noises.
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