| 摘要 |
PURPOSE:To prevent the fluorescent face of a CRT from being damaged by erasing a CRT beam while detecting that a vertical deflection current is less than a prescribed level. CONSTITUTION:The vertical deflection current outputted from an outputting stage 1 flows through a vertical deflection winding 2, and reaches through a coupling capacitor 3 and a feedback resistor 4 to a ground side. And also, the vertical deflection current is converted into a certain voltage level by partial potential resistor 5 and 6, and inputted through a diode 19 and a resistor 21 to a signal processing IC 8. When the vertical deflection current outputted from the outputting means 1 is 0 or extremely small, the output of an operating amplifier 17 is a high level. This high level output signal is impressed through a diode 18 to the input terminal of the IC 8, and the input terminal is held to high level. Thus, a video signal transmitted to the CRT is made to be a black level, or less than the black level, by the operation of the IC 8, so that the CRT beam can be erased during the entire period. Thus, the damage to the fluorescent face of the CRT can be prevented. |
