| 摘要 |
PURPOSE:To reduce a tracking error, by forming index lines, to be installed on the inner side of a screen of a cathode-ray tube, alternately with two types of materials different in radiating wavelength each, and constituting a light collecting plate of a photodetector, to be installed on an inclined outer surface of the cathode-ray tube, with a plate dispersed with such materials that absorb each of wavelengths alone. CONSTITUTION:A lot of color phosphor stripes of red, green and blue are arranged on a screen inner surface 1 of a cathode-ray tube in a way each stripe is next to each non-luminous guard band 4, covering the whole body with a metal-backed screen 5. On the top of the metal-backed screen, both index lines 6A and 6B which have different radiating wavelengths with each other adopted by materials, for example, YAG; Ce, P47 are alternately installed. And, a photodetector 10 receiving light from these lines is installed in the outside of a light receiving window 8 without a metal backed-screen 7 of the cathode-ray tube, but at this time, fluorescent dyes, which has the wavelength of the line 6A alone passed, are impregnated in a light collecting plate 11A constituting this detector and dyes, which has the wavelength of the line 6B alone passed, in a light collecting plate 11B, respectively. In addition, on these ends, there are provided with photoelectric conversion devices 12A and 12B via each of grease layers 13A and 13B.
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