| 摘要 |
Abrupt transitions in the televised scene between areas of low and high brightness can occasion horizontal sweep system loading to produce raster distortion. Scan compensation circuitry which utilizes the loading of the horizontal sweep system as an input corrects raster position distortion, raster width distortion and raster tearing distortion. Position distortion is corrected by delay of the start of horizontal retrace in order to shift the start of trace. Control of horizontal yoke drive to maintain an appropriate ratio of yoke drive to CRT anode voltage serves to corrects width distortion. Raster tearing is prevented by limiting the drive to the picture tube when sweep system loading would exceed a predetermined threshold.
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