Cathode ray tube apparatus
First Claim
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1. Cathode ray tube control apparatus comprising:
- means to apply a correction factor signal to a cathode ray tube having at least one set of deflection means, each of said correction factor signals being calculated to correct for distortions of the cathode ray tube beam operation when an associated one of a plurality of areas of the cathode ray tube screen is scanned,a digital data store for storing the correction factor signals for each said area of the screen in digital form and,means for reading out digital correction factor signals from the digital data store when the associated area of the screen is scanned and converting the digital signal to analog from before it is applied to the deflection means of the cathode ray tube, in whichthe correction factor signal for each of said areas of cathode ray tube screen has at least two components, a basic correction signal and a fine correction signal, andsaid digital data store has a first portion for storing in digital form the basic correction signal and a second portion for storing in digital form the fine correction signal.
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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.
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Citations
11 Claims
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1. Cathode ray tube control apparatus comprising:
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means to apply a correction factor signal to a cathode ray tube having at least one set of deflection means, each of said correction factor signals being calculated to correct for distortions of the cathode ray tube beam operation when an associated one of a plurality of areas of the cathode ray tube screen is scanned, a digital data store for storing the correction factor signals for each said area of the screen in digital form and, means for reading out digital correction factor signals from the digital data store when the associated area of the screen is scanned and converting the digital signal to analog from before it is applied to the deflection means of the cathode ray tube, in which the correction factor signal for each of said areas of cathode ray tube screen has at least two components, a basic correction signal and a fine correction signal, and said digital data store has a first portion for storing in digital form the basic correction signal and a second portion for storing in digital form the fine correction signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. The method of applying a convergence correction factor signal to a color cathode ray tube having at least one set of deflection means, each of said correction factor signals being calculated to correct for distortions of the cathode ray tube beam operation when an associated one of a plurality of areas of the cathode ray tube screen is scanned, comprising:
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storing the correction factor signals for each said area of the screen in digital form and, reading out the digital correction factor digital signals when the associated area of the screen is scanned and converting the digital signal to analog form and then applying it to the deflection means of the cathode ray tube, the correction factor for each of said areas having two components, a basic correction component and an error correction component, said method further including altering said error correction components during operation of said cathode ray tube, as needed to achieve the desired distortion correction. - View Dependent Claims (9)
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10. In a display system, the method of providing convergence correction signals to a plural beam color cathode ray tube display which comprises:
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providing and maintaining in digital storage basic digital information defining nominal convergence requirements of said color cathode ray tube with respect to various areas of the screen thereof, operating the convergence means of said display in accordance with said information from said basic storage to provide a nominal convergence of said beams, using the result to define digital information characterizing the error in said nominal convergence, and using said error information to provide final convergence signals for said display. - View Dependent Claims (11)
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Specification