| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the need for a conventional large photosensor unit and an A/D converter, and to detect a center position easily simply by moving the travel direction of an alignment pattern in horizontal and vertical directions. SOLUTION: In the automatic convergence correction circuit, a plurality of photosensor units are arranged at a fixed interval along a periphery on the rear of a screen, and four small sensors are arranged in a measure shape on the same board in each photosensor unit. The detection output of the small sensors is inputted to an arithmetic unit for addition/subtraction operation of each detection output, and the position of the photosensor unit is detected for horizontal and vertical directions based on the arithmetic result. Convergence deviation distance to a position that is subjected to converse adjustment in advance and a detected photosensor unit position is obtained, and convergence correction is made based on the positional relationship.
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