| 摘要 |
PURPOSE:To realize an easy-to-see method for the mixed display signal, by having a producing circuit for the display signals of both positive and negative polarities and switching the display signal in accordance with the level of a video signal. CONSTITUTION:The video signal input (a) is divided into two parts by a dividing circuit 10. One of the divided two inputs is applied to a comparator 12 through an LPF11. A display signal producing circuit 14 is provided to a TV monitor to mix the display signal with the video signal and display them. The circuit 14 applies the signals of positive and negative polarities to a switch circuit 15 as the display signal. The comparator 12 compares the reference level given from a reference voltage circuit 13 with the output 6 of a low pass filter and controls the circuit 15 to switch a display signal (d) of positive polarity and a display signal (e) of negative polarity when the output (b) is large and small respectively. The selected display signal is mixed with the video signal at a mixing circuit 17 and through a level control circuit 16. Thus the mixed display is carried out in accordance with the level and gradation of the video signal to ensure an easy-to-see display. |
