Browse Prior Art Database

Multi Intensity Pile Up Correction

IP.com Disclosure Number: IPCOM000092228D
Original Publication Date: 1968-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Gundrum, RJ: AUTHOR

Abstract

In CRT vector generators employing asynchronous electromagnetic deflection, the pile-up effect occurs during vector generation when the magnetic yoke current change slows beam travel prior to the beam reaching the deflection end point. While corrections or adjustments minimize the effect for a single intensity display, the problem is particularly acute in a display utilizing different intensity levels. This is because correction at one intensity level provides over or under correction at different levels of intensity. This vector generation system incorporates an automatic end point correction system for three intensity levels, normal, dim and bright.

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Multi Intensity Pile Up Correction

In CRT vector generators employing asynchronous electromagnetic deflection, the pile-up effect occurs during vector generation when the magnetic yoke current change slows beam travel prior to the beam reaching the deflection end point. While corrections or adjustments minimize the effect for a single intensity display, the problem is particularly acute in a display utilizing different intensity levels. This is because correction at one intensity level provides over or under correction at different levels of intensity. This vector generation system incorporates an automatic end point correction system for three intensity levels, normal, dim and bright.

Digital signals indicative of the selected intensity are applied via lines 11 and 12 to decoder 13. The output of the latter causes the potential level corresponding to the selected intensity to be applied from cathode drive circuit 15 to cathode 17 of CRT 19. This system includes a dynamic intensity correction circuit 21 to provide uniform intensity in asynchronous display systems. The intensity correction signals are applied via line 22 to blanking control circuit 23. This responds to logic control line 25 to apply the blank-unblank signal on line 26 to grid drive circuit 28. The cathode potential, which controls the display intensity, is also applied via line 27 to cathode feedback amplifier 29, the output of which is applied to pile-up correction circuit 31. Since beam current...