| 摘要 |
PURPOSE:To prevent the degradation of a liquid crystal by generating forcibly a synchronizing signal in a device and setting video data to be written to a memory to '0' when it is detected that the synchronizing signal is not inputted. CONSTITUTION:When the synchronizing signal is not inputted, this state is detected by a synchronizing signal detecting and generating circuit 3. This circuit 3 generates the synchronizing signal internally then. Simultaneously, a signal indicating that the synchronizing signal is not inputted is outputted to a data switching circuit 4. The data switching circuit 4 receives this signal to output '0' (black display) as video data. Hereafter, these signals are processed in the same manner as normal input of the synchronizing signal and video data. Consequently, a DC is not impressed to a liquid crystal and the potential difference between the segment terminal and the common terminal of the liquid crystal is '0'. Thus, the degradation of the liquid crystal due to input of the synchronizing signal from the external is prevented.
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