| 摘要 |
PROBLEM TO BE SOLVED: To provide a flat display device capable of preventing degradation of display characteristics due to the DC drive of a display panel caused by the abnormality of a signal which is to be supplied from a display control part or the like. SOLUTION: Signal management control parts 471 to 47n of respective scanning drivers LSIs are cascaded and they have the same constitution. The signal to be detected of the control part 471 is a data signal latching clock LP which is to be impressed on a terminal CKB1 and the signal to be detected of the control part 472 is a frame starting signal SP which is to be impressed on a terminal CKB2 and the signal to be detected of the control part 47n is an alternating clock FR which is to be impressed on a terminal CKBn. The control part 471 has a sequence processing circuit 51 consisting of a signal stoppage detecting circuit 48 detecting the stoppage of the signal to be detected of the part 471, a signal delaying circuit 49 and a logical circuit 50. When the oscillation of the signal SP is stopped, outputs T1 to Tn of the circuit 51 are changed to L levels and a display-off signal, the inverse of DF becomes to be in an L level and a liquid crystal panel is forcibly set into a display-off mode. Thus, even when the signal SP is stopped by some cause, since a liquid crystal application voltage is dropped to zero, the DC drive of liquid crystal is avoided and the degradation or the like of liquid crystal are prevented.
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