| 摘要 |
<p>PURPOSE:To display the raster scan of signals obtained from PPI polar coordinate indication without non-uniformities in brightness by performing smoothing only for necessary periods as the function of brightness changes of adjacent display points. CONSTITUTION:Dot brightness signals A from a scan converter 60 and delayed dot brightness signals B through a latch 41 of a smoothing control part 40 are compared to each other. If the adjacent dots are different in the brightness, a comparator 42 outputs '1' to control a selector 53 through a shift register 43 and an OR circuit 48. The selector 43 selects smoothed data from a data converter 30 to effect smoothing for the dot period. Similarly, the output of an AND gate 50 is turned to '1' by a signal that needs to be smoothed in accordance with the 3-dot brightness pattern so that the smoothing is effected during the 3-dot period. When the change in the brightness is higher than a prescribed value, the smoothing is carried out for a prescribed period so that raster display of the PPI polar coordinate is performed without the brightness non-uniformities due to the smoothing.</p> |
