| 摘要 |
PURPOSE: A beam index type cathode-ray tube is provided to restrict an increase in a black level current value so as to raise contrast and improve landing characteristic of electron beams by increasing the quantity of information of an index signal. CONSTITUTION: A beam index type cathode-ray tube includes a fluorescent screen, the first and second index stripes, the first and second light detector, an index signal processor, a phase controller, and an adder. The fluorescent screen has a plurality of red, green and blue fluorescent stripes and a black matrix between neighboring stripes. The first and second index stripes are alternately arranged on the black matrix. Each of the index stripes emits light with a unique wavelength according to electron beams. The first light detector detects the index beam emitted from the first index stripe to output the index beam as an electrical A index signal. The second light detector detects the index beam emitted from the second index stripe to output the index beam as an electrical B index signal. The index signal processor synchronizes A and B index signals with color signals to control the electron beams. The phase controller compensates a phase difference between the index signals. The adder adds up the A and B index signals to output a C index signal with frequency increased twice the frequency of each of the A and B index signals.
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