公开(公告)号：WO1979000484A1

公开(公告)日：1979-07-26

申请号：PCT/US1978000258

申请日：1978-12-28

Applicant: NCR CORP

Inventor： NCR CORP ,  CHOUDHURY R

IPC: G06F03/14

CPC classification number: G06F3/0383

Abstract: A light pen detection system used in a data display system utilizes a cathode ray tube (CRT) in which characters displayed on the screen of the cathode ray tube (20) are detected by the light pen (32), the detection or the character by the light pen (32) resulting in the background inversion or the character sensed thereby providing a visual indication to the operator of the sensed character. A locking circuit (72) is provided which, upon the sensing of a displayed character by the light pen (32), prevents the visual indication of a further character as long as the light pen (32) continues to receive light from the originally sensed character.