| 摘要 |
PURPOSE:To obtain easily a deformed screen without producing distortion and the unevenness of luminance, by controlling both vertical and horizontal blanking periods from the start to end points of the horizontal and vertical scanning respectively. CONSTITUTION:The 1st and 2nd triangular wave generating circuits 10 and 11 generate triangular waves A and B synchronizing with horizontal and vertical synchronizing signals HS and VS respectively. A voltage comparator 13 compares a clamped signal C obtained by clamping the wave B with the wave A and produces an output signal D. This signal D is converted into a pulse form by a waveform shaping circuit 14 and then supplied to a video signal processing circuit 15 in the form of a blanking pulse BP. The projecting screen which is controlled by the pulse BP has a hexagon screen formed by erasing four corners from an ordinary square screen. Therefore it is possible to obtain a large screen on a dome-shaped screen by synthesizing the exagonal screen with plural projectors. |
