| 摘要 |
PURPOSE:To raise the sensitivity of an abnormal voltage detection due to hold- down at the time of abnormal rise of +B by stopping a horizontal oscillation circuit, when an output of an increase circuit for synthesizing output voltages of a first and a second low voltage power source circuit and taking large a variation of the output voltage exceeds a prescribed value. CONSTITUTION:When a +B voltage rises abnormally, a positive voltage of a line 7 and a negative voltage of a line 15 become large, a difference voltage between a-input terminal and a + input terminal of a comparator 12 becomes large by a portion obtained by synthesizing a voltage rise portion of each line 7, 15, and an output of the comparator 12 turns on a Zener diode ZD. Subsequently, since a transistor 14 is tuned off, a horizontal oscillation stopping circuit 9 receives a high level input and operates, and stops a horizontal oscillation circuit 10. Therefore, a switching operation of a horizontal output transistor 6 also stops, a flyback transformer 1 becomes inoperable, and a rise of a high voltage is suppressed. |
