Cathode ray tube and intensity controlling method

An intensity controlling method for controlling intensity of an image displayed on an image display apparatus constructed to form a single picture plane by joining a plurality of split picture planes so as to be partially overlapped each other,

• the method comprising:
• a step of directly or indirectly obtaining a necessary first correction factor on the basis of the signal level of a present video signal and a pixel position in the orthogonal direction corresponding to the present video signal by using first correction factors stored in a first factor storing means in said image display apparatus for storing at least some of a plurality of first correction factors associated with signal levels of the video signals and pixel positions in a direction orthogonal to the overlapping direction, the some first correction factors being in representative pixel positions;
• and
• a step of changing a value of the signal level of a video signal which is referred to when a second correction factor is obtained on the basis of the first correction factor obtained;
• a step of directly or indirectly obtaining a second correction factor to be used for intensity modulation control on the basis of the changed signal level and the pixel position in the overlapping direction corresponding to the present video signal by using the second correction factors stored in a second factor storing means in said image display apparatus for storing at lest some of a plurality of second correction factors associated with signal levels of the video signals and pixel positions in the direction of overlapping the plurality of split picture planes, the some second correction factors being at representative signal levels;
• and
• a step of performing the intensity modulation control on each of the video signals for the plurality of split picture planes so that a total of intensity values in the same pixel position in an overlapped area on the picture plane scanned on the basis of the video signals for the plurality of split picture planes becomes equal to the intensity in the same pixel position in an original image by using the second correction factor obtained.

An apparatus for controlling intensity of an image displayed on an image display apparatus constructed to form a single picture plane by joining a plurality of split picture planes so as to be partially overlapped with each other, the image display apparatus comprising:

• first factor storing means for storing at least some of a plurality of first correction factors associated with signal levels of the video signals and pixel positions in a direction orthogonal to the overlapping direction, the some first correction factors being in representative pixel positions;
• and
• second factor storing means for storing at least some of a plurality of second correction factors associated with signal levels of the video signals and pixel positions in the direction of overlapping the plurality of split picture planes, the some second correction factors being at representative signal levels,
• means for directly or indirectly obtaining a necessary first correction factor on the basis of the signal level of a present video signal and a pixel position in the orthogonal direction corresponding to the present video signal by using the first correction factors stored in the first factor storing means;
• means for changing a value of the signal level of a video signal which is referred to when the second correction factor is obtained on the basis of the first correction factor obtained;
• means for directly or indirectly obtaining a second correction factor to be used for intensity modulation control on the basis of the changed signal level and the pixel position in the overlapping direction corresponding to the present video signal by using the second correction factors stored in the second factor storing means;
• and
• means for performing the intensity modulation control on each of the video signals for the plurality of split picture planes so that a total of intensity values in the same pixel position in an overlapped area on the picture plane scanned on the basis of the video signals for the plurality of split picture planes becomes equal to the intensity in the same pixel position in an original image by using the second correction factor obtained.