| 摘要 |
PROBLEM TO BE SOLVED: To perform correct position detection at a low cost in the scanning position detecting circuit of a convergence correcting device. SOLUTION: In the scanning position detecting circuit 30, an output signal from a photosensor is amplified in an amplifier circuit 24 via a terminal 28 and noise reduction is performed in a low-pass filter 25 and the comparison between the output signal of the filter and a prescribed DC level is performed in a binary circuit 26 and a binary signal is generated and the accumulating processing of pulse widths of a prescribed period is performed in a pulse width accumulating circuit 27. A microcomputer judges when the cumulative value of pulse widths for the circuit 27 becomes the maximum by moving a video for automatic adjustment in some steps with respect to an object photosensor and makes moving steps at this time a moving amount on the sensor and it calculates a moving amount distribution of the whole of the screen of a display based on moving amounts on respective photosensors by a prescribed operation and controls a convergence device so as to perform the convergence correcting processing of the whole of the screen in accordance with this moving amount distribution.
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