| 摘要 |
PURPOSE:To prevent a noise and a turbulent image from being projected on a high-grade display even when an input video signal is not a high-grade television signal or the high-grade television signal is interrupted by automatically switching an output signal according to whether a synchronization is locked or not. CONSTITUTION:By the output of a frame pulse detecting circuit 18 to detect the lock and unlock of the synchronization to the high-grade television signal and to output them, an output signal switching circuit 113 is switched. The output signal of a signal processing circuit 110 and the output signal of a pattern generating circuit 114 are outputted at the time of a lock condition and at the time of an unlock condition, respectively. Thus, when the input signal is not the high-grade television signal or when the high-grade television signal is interrupted, the noise and turbulent image can be prevented from being projected on the high-grade display, and an arbitrary pattern can be projected. |
