447R
25
Luminance uniformity
With full white field and with the Nominal brightness luminance and with
the contrast control set for a luminance of 100cdm
2
at the center of the
screen measure the luminance uniformity. The luminance at anywhere in
the display area must be more than 75 % of the luminance at the center.
This uniformity specification must be fulfilled the tube facing east, west,
north and south.
Maximum Background Luminance
The luminance of the background, measured at centre of the screen,
without active video
1cdm
2
(nits) ≤L0 ≤ 7cdm
2
(nits)
6.9. Convergence
- Definition: Misconvergence is defined as the distance between centres of the red,
green and blue beams at the screen using rectangular coordinates. The
centre is defined as the midpoint of the brightest portion of the beams.
- Measurements:Using a crosshatch test pattern adjust each gun to produce white dim
lines. Adjust brightness control so that background will j ust disappear. Set
contrast control to give a luminance level of 50 cdm
2
(nits) on a white
50 mm x 50 mm square at the screen center.
- Requirements: For horizontal sync frequencies above 48 kHz:
Inside a circle with a diameter equal to the height of the active screen mi
nor defect ≤ 0.25 mm, maximum ≤ 0.3mm.Elsewhereinsidetheactive
screen area minor defect ≤ 0.35, maximum ≤ 0.4 mm.
F or horizontal sync frequencies below 48 kHz:
Inside a circle with a diameter equal to t he height of the active screen
≤0.4 mm. Elsewhere inside the active screen area ≤0.5 mm.
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