Method and apparatus for screening slot-mask, stripe screen color cathode ray tubes

摘要

This disclosure depicts method and apparatus for screening slot-mask, stripe screen type color cathode ray tubes particularly method and apparatus for improving screen stripe uniformity and edge definition. The method involves supporting a curved, approximately rectangular faceplate which has on its concave inner surface a photosensitive coating and which has supported adjacent its inner surface an exposure mask defining an array of columns of spaced slots oriented parallel to the minor axis of the faceplate. A line source of radiation actinic to said coating is supported on or near a central axis of the faceplate. The disclosed method includes producing a virtual image of the line source which appears, when viewed from off-axis points on the faceplate, to be rotated in a direction effective to decrease an unwanted rotational displacement of the mask slot images induced by the relative geometry of the line source, the mask slots and the faceplate inner surface. Stripe width uniformity and edge definition is thus improved. Preferred apparatus for implementing the disclosed method includes a negative meniscus lens.