| 摘要 |
PURPOSE:To measure the displacement of an electron beam against the center of a fluorescent screen section easily and quickly by controlling the adjusting DC current value fed to a deflecting coil means so that center marks provided on the fluorescent screen section are illuminated. CONSTITUTION:A fluorescent screen section 35 contains an image display region 35a including multiple index phosphor stripes and three-primary color phosphor stripes and center marks 50, 51 provided on the peripheral portion 35b of the image display region 35a. An electron beam scans the fluorescent screen section 35 in the vertical scanning direction. In this case, if the center marks 50, 51 provided on the peripheral portion 35b of the image display region 35a on the fluorescent screen section 35 are not illuminated, a displacement exists between the center in the horizontal scanning direction of the image display region 35a and the center of the horizontal scanning range of the electron beam.
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