Browse Prior Art Database

"Cigaring" Correction

IP.com Disclosure Number: IPCOM000079632D
Original Publication Date: 1973-Aug-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Lillard, JW: AUTHOR [+2]

Abstract

The phenomenon called "cigaring" occurs in cathode-ray tube (CRT) displays, which utilize an auxiliary small angle deflection yoke in addition to the main deflection yoke. The small-angle yoke (character yoke) exhibits greater deflection sensitivity near the center of the CRT screen than at its edges. This problem is particularly acute in large-angle cathode-ray tubes, of the type used in television sets. It is aggravated by pincushion corrected main deflection yokes and by small diameter CRT necks. The effect must be eliminated, in order to use low-cost television type CRT's in displays of this type.

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"Cigaring" Correction

The phenomenon called "cigaring" occurs in cathode-ray tube (CRT) displays, which utilize an auxiliary small angle deflection yoke in addition to the main deflection yoke. The small-angle yoke (character yoke) exhibits greater deflection sensitivity near the center of the CRT screen than at its edges. This problem is particularly acute in large-angle cathode-ray tubes, of the type used in television sets. It is aggravated by pincushion corrected main deflection yokes and by small diameter CRT necks. The effect must be eliminated, in order to use low-cost television type CRT's in displays of this type.

The dominant effect of cigaring is a lessening of vertical character yoke sensitivity as the main deflection moves the beam away from center screen to left or right, and a lessening of horizontal character yoke sensitivity as the main deflection moves the beam vertically away from center screen. A method is described for compensating for this dominant effect, by using the main horizontal deflection signal to control the magnitude of the vertical character deflection signal, and by using the main vertical deflection signal to control the magnitude of the horizontal character deflection signal.

Fig. 1 shows one circuit configuration which will provide a correction for the vertical character deflection sensitivity. An additional similar circuit would be required to correct the horizontal character deflection sensitivity. The "differential absolute value circuit" 1 produces a voltage, which is approximately proportional to the magnitude of the hor...