JPS6424585A - Convergence device - Google Patents

Abstract

PURPOSE:To detect a static color slippage with a simple circuit constitution and with good accuracy and to automatically execute the static convergence correction while an image is displayed, even when an unnecessary light except a pattern signal is received by executing the symmetrical position detection to the reference position of a detector and detecting the dislocation quantity to the reference position in which both detecting signals are equal. CONSTITUTION:By photoelectric converting elements 30 and 31 provided symmetrical to a reference position on a screen 20, the dislocation is detected, both photoelectric converting outputs contrary to the reference position from the detector is subtracted, the maximum value and the minimum value of the subtracting output are detected 33 and 34, and the dislocation quantity to the reference position, which both detecting signals are equal, is detected. A convergence correcting circuit 37 is controlled by the detecting signal, the amplitude of the photoelectric converting output from the detector is detected, and the detecting period is controlled by the detecting signal. Thus, even when the unnecessary light is made incident on the detector while the video is reflected on the screen, good accurate automatic static convergence correction can be executed.