Duty factor and contrast in scanned displays

Light-modulator displays can be built so that an unexcited element delivers either maximum or minimum light to the observer. For scanned displays, the duty factor for an individual element is in general less than unity, so that the contrast available from the display will be less than the contrast from an individual element considered in isolation. If the display is so arranged that unenergized elements produce minimum light, contrast is not as severely degraded by duty factors less than unity as it is if unenergized elements produce maximum light. The same conclusion holds for light-emitting displays.