Method of reducing deflection errors for flat intelligent tracking (FIT) CRTs
OwnerWillem Lubertus Ijzerman, Marcellinus Petrus Carolus Michael Krijn +2inventors
InventorsWillem Lubertus Ijzerman, Marcellinus Petrus Carolus Michael Krijn, Jozef Johannes Maria Hulshof, Dirk Johan Adriaan Teuling
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Abstract
The present invention relates to a method and a picture display device for reducing cathode drive-induced deflection errors in an index type cathode ray tube (CRT), and especially a flat intelligent tracking (FIT) CRT. The method comprises the steps of generating at least one electron beam; driving said beam by modulating a cathode potential; predicting a deflection error for the beam due to the cathode drive; and controlling compensation means in accordance with said prediction for reducing said deflection error.
Claims12
A method of reducing cathode drive-induced deflection errors in an index type cathode ray tube (CRT), comprising the steps of:
- generating at least one electron beam;
- and
- driving said beam by modulating a cathode potential, characterized in that it further comprises the steps of:
- predicting a deflection error for the beam due to the cathode drive;
- and
- controlling compensation means in accordance with said prediction for reducing said deflection error.
The method of any one of the preceding claims, wherein the compensation means comprises at least one deflector for deflecting the beams.
The method according to any one of the preceding claims, wherein the prediction of the deflection error is based on at least the cathode potential and the frame current.
The method according to any one of the preceding claims, wherein said compensation means is additionally controlled in accordance with a feedback tracking signal from the index type CRT.
A picture display device comprising an index type cathode ray tube (CRT) having means (1) for generating at least one electron beam and a display screen (2), the CRT using modulation of the cathode potential for driving said beam, characterized in that it further comprises a control unit (6′;8) adapted to predict a deflection error for the beam due to the cathode drive and to control compensation means (3′;7) in accordance with said prediction for reducing said deflection error.
Dependencies are inferred from the claim text.