公开(公告)号：BR7708542A

公开(公告)日：1978-09-05

申请号：BR7708542

申请日：1977-12-21

Applicant: IBM

Inventor： HENEGHAN M ,  HALLET M ,  SOWTER B

IPC: G06F3/153 ,  G09G1/00 ,  G09G1/04 ,  G09G1/28 ,  G09G5/30 ,  H04N3/23 ,  H04N9/28 ,  H01J29/46

Abstract: A three color gun cathode ray tube has convergence correction signals derived from digital signals stored in a digital data store. The screen of the tube is divided into a plurality of areas and a digital correction signal derived for each area. The system is arranged so that when the three beams are scanning a particular area the digital correction signal associated with that area is read out from the digital store, passed through a digital to analog converter and then applied to the convergence coils of the tube.