| 摘要 |
PROBLEM TO BE SOLVED: To automatically perform mask processing of screen display for a specific video signal, in a video display device to define plural kinds of video signals in various forms as inputting objects. SOLUTION: An analog RGB video signal, a signal of HD with a frequency range of 31.47 kHz and a signal of VD with 59.94 Hz and with 2 lines of vertical synchronization width are outputted from a personal computer 1. In addition, an analog RGB video signal, formed by converting a general video signal, such as a VTR into a progressive form and signals of HD and VD with the same frequency as that of the personal computer 1 and with six lines of vertical synchronization width are outputted from a scan converter 3. Any video signal selected by a selecting part 4a of the video display device 4 is made into a digital signal by an A/D-converting part 4b and inputted in a mask processing part 4d and a switching circuit 4e. In addition, a discrinating part 4c discriminates each of horizontal and vertical cycles and the vertical synchronization width, on the basis of the HD and the VD from the selecting part 4a and sets the first switching circuit 4e in a mask processing part 4d, in the case of the signal converted into the progressive form. |
