| 摘要 |
PURPOSE:To correct properly left and right pincushion distortion by counting a prescribed number of an index signal and extracting the signal from a run-in signal and controlling a power voltage of a horizontal deflection circuit with a voltage value in response to the pulse width. CONSTITUTION:The index signal obtained from a photoelectric converter 7 is applied to a decoder 10 via a filter 8 and a pulse shaping device 9. An output of the decoder 10 is converted into a frequency in matching with the period of arrangement of three primary color fluorescent stripes by a frequency converter 11, mixed with a chrominance signal by a mixer 12, added with a luminance signal by an adder 13 and fed to a CRT1. Further, the run-in signal from the photolectric converter 7 is applied to a pincushion correcting circuit 17 via the 2nd pulse shaping device 14, and a voltage in which a voltage value scanning horizontally the center of screen is large and a voltage value scanning horizontally the upper and lower parts of the screen is small is used as a power voltage to the horizontal deflection circuit, allowing to correct almost completely the left and right pincushion distortion.
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