Method and apparatus for improving vertical sharpness of picture tubes
AssigneeThomson Consumer Electronics, Inc.
InventorsAndrew D. Hackett, Werner Boie, Nadine Bolender
Life of this patent
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Abstract
Large format TV tubes must produce a high peak brightness in order to be acceptable to the user. This results in a large beam current in bright areas of the picture and in a subsequent defocusing of the resulting spot on the display and in a loss of the sharpness of vertical and horizontal transitions. The apparent sharpness of a vertical transition is gained by modifying the deflection of the TV receiver such that, at vertical transitions, the line on the bright side of the transition is deflected away from the transition region. Advantageously, the amount of vertical scan modulation corresponds to a multi-level control signal and depends on the grey levels of the transition.
Claims10
Method for improving an apparent vertical sharpness of pictures displayed with a line structure on a picture tube, by a beam that is deflected in a vertical direction, comprising the step of, additionally deflecting the beam in the vertical direction by an amount that is determined in accordance with brightness-depending variations of a spot size of displayed lines, whereby the beam is deflected towards a bright side of a transition region formed by line segments having brightness transitions in the vertical direction such that the direction of said additional deflection in a given vertical deflection cycle is unaffected by an order of said vertical deflection cycle within a sequence of vertical deflection cycles.
Dependencies are inferred from the claim text.