| 摘要 |
PURPOSE:To detect the position deviation of convergence with high accuracy and sensitivity by controlling the detection period of a detector to detect the position synchronously with the period of a pattern signal detected by the detector. CONSTITUTION:When a pattern signal is displayed on a screen 20, the position of the adjusting point in the pattern signal is detected by the detector 30 provided on the screen 20 and stored in a storage circuit 32. In this case, the period of the detection signal, that is, the period of the pattern signal is used for the detection synchronously by a detection period control circuit 31 to control the detection period of the detector 30. When the position data of the adjusting point is obtain with respect to a green pattern signal and red pattern signal, both the position data are compared by a comparator circuit 33 and the convergence correction is controlled so that the red pattern signal is at the same position of the reference green pattern signal on the screen by the convergence correction circuit 34.
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