PICTURE DISPLAY DEVICE

摘要

PURPOSE:To make a picture stable by detecting the change in a deflecting position of a minimum variable amount and focus state changed at each field so as to adjust and maintain the deflecting position and the focus state to the best state. CONSTITUTION:Red fluorescent substances 43a-43p in horizontal direction coincident with the vertical deflection width and blue/green/red fluorescent substances 44a-44f in vertical direction coincident with the horizontal deflection width are coated in stripe to the end other than a fluorescent substance 20 of a picture display plane of a screen board 9. The amount of light emitted by the fluorescent substance 43 is detected by a photoelectric element 45 and A/D-converted. The signal subject to A/D conversion is fed to offset/focus/gain control memories 48-50, the emission amount of the fluorescent substance 43 before and after the content of each content memory is changed is compared at each field, the content of the control memories 48-50 is fixed at the best position so as to control the offset/focus/amplitude of the vertical deflection signal in the best state.