| 摘要 |
PURPOSE:To eliminate unsightly screen due to the fluctuation in a blanking position, by providing a screen circumferential blanking pulse so as to be inputted or interrupted in response to the strength of electric field. CONSTITUTION:The level of a synchronizing signal (j) inputted to an input section of a detection circuit 11 is reduced at a weak electric field. This signal (j) is detected at a diode 111, smoothed at a capacitor 112 and a detection signal (k) is outputted from the circuit 11. A voltage comparison circuit 12 compares the signal (k) with a reference voltage Vs, and outputs a high level H voltage only when the signal (k) is higher than the voltage Vs. A transistor 13 is set on only when the output voltage of the circuit 12 is high level H and gives a screen circumferential blanking pulse (e) applied to an input section (m) to an output section (n). Thus, the pulse (e) is not outputted to the output section (n) at the weak electric field. |
