Browse Prior Art Database

Semi-Automated Correction for Crt and Deflection Yoke Distortion

IP.com Disclosure Number: IPCOM000034968D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 90K

Publishing Venue

IBM

Related People

Dickerson, JA: AUTHOR [+3]

Abstract

Each CRT/yoke combination requires unique magnetic corrections for centering, N-S and E-W pincushion correction, and beam distortion. These unique magnetic correction signatures are obtained with the front-of-screen fixture and hardware shown in Fig. 1. Yoke modifications are shown in Fig. 2 to accommodate two flexible vinyl rods which have been loaded with neodymium/iron/boron magnetic filler. (Image Omitted) Under program control, analog outputs from D/A converters first supply current waveforms to electromagnets temporarily placed around rear of yoke (replacing the centering rings). Signals from front- of-screen sensors serve in a closed-loop servo system to obtain centering. This information is used to "write" a magnetic pattern on one of the vinyl/magnetic filler rods which is then installed on the rear of the yoke.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Semi-Automated Correction for Crt and Deflection Yoke Distortion

Each CRT/yoke combination requires unique magnetic corrections for centering, N-S and E-W pincushion correction, and beam distortion. These unique magnetic correction signatures are obtained with the front-of-screen fixture and hardware shown in Fig. 1. Yoke modifications are shown in Fig. 2 to accommodate two flexible vinyl rods which have been loaded with neodymium/iron/boron magnetic filler.

(Image Omitted)

Under program control, analog outputs from D/A converters first supply current waveforms to electromagnets temporarily placed around rear of yoke (replacing the centering rings). Signals from front- of-screen sensors serve in a closed-loop servo system to obtain centering. This information is used to "write" a magnetic pattern on one of the vinyl/magnetic filler rods which is then installed on the rear of the yoke. A second configuration of electro-magnets is placed around the front of the yoke and driven by the D/A converters. Correction waveforms are obtained for each of the magnet positions. The second vinyl magnetic filler rod is written and installed on the yoke. In Fig. 3, a simplified fixture is presented for "writing" the magnetic signatures.

1

Page 2 of 2

2

[This page contains 5 pictures or other non-text objects]