Method and apparatus for testing a CRT display under beam duty c

Details Method and apparatus for testing a CRT display under beam duty c Method and apparatus for testing a CRT display under beam duty c

1983-11-23

1985-08-20

Britton, Howard W.

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

324404, H04N 702

Patent

active

045367922

ABSTRACT:
A method and apparatus for testing the geometry of a cathode ray tube raster scan under beam duty cycle variation. Alternate polarities of white on black and black on white images of a test pattern are displayed on the CRT screen, and the displacement of a reference point from one polarity to the other is measured to determine quantitatively the amount of displacement. Preferably, the pattern comprises a plurality of regularly arranged and spaced graphic elements, such as a bar, dot or dot grating pattern, wherein the pattern occupies a low percentage of the screen area. By alternately switching the polarity, the electron beam of the CRT undergoes wide swings in the amount of current it draws from the high voltage supply, and the amount of image displacement and size deviation can be readily measured.

REFERENCES:
patent: 4093960 (1978-06-01), Estes

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