Jitter; Focus; Convergence - Nokia 445PRO Service Manual

6.10 Jitter

Image motion in terms of dynamic pixel displacement shall be defined as jitter.
(MPR 1990:10, 1.07)
The horizontal and vertical displacement of any pixel using the "convergence" dot and cross hatch
pattern measured using microscope with appropriate magnification.
The maximum displacements in both the horizontal and vertical directions must be less than 0.1
mm.
6.11 Chromaticity
Factors affecting chromaticity include colour set up, temperature and tracking, colour purity and
uniformity, adequate degaussing, and registration.
With a fully driven flat field of the active raster size, with the brightness control set so the background
raster is just extinguished, the contrast control set to maximum, check first each of the primary
colours, and then white. Visually observe the display from a distance of 0.5 m for no longer than 3
seconds with an ambient illumination of approximately 500 lux.
The screen must appear uniform for each of the primary coloured rasters and for a white raster, with
no observed impurity in colour.

6.12 Focus

Definition: Focus is defined as the sharpness of displayed characters.
Measurements:
Set the brightness control so that the background raster just disap-
pears and set with the contrast control a screen centre brightness of
100 cd/m2 at a white 50 mm x 50 mm square at the centre of the
screen. Single pixel wide cross---hatch test pattern (red, green and
blue).
Requirements: The test pattern must be sharp in vertical and horizontal directions.
The test pattern must be sharp in vertical and horizontal directions. Optimised within line frequency
range 60 kHz to 121 kHz

6.13 Convergence

Definition:
Misconvergence is defined as the distance between centers of the red,
blue and green beams at the screen using rectangular coordinates.
The center 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 just disappear.
Set contrast control to give a luminance level of 50 cd/m2 on a white 50
mm x 50 mm square at the screen center.
Requirements:
For horizontal sync frequencies above 58 kHz:
Inside a circle with a diameter equal to the height of the active screen £
0.3 mm. Elsewhere inside the active screen area £ 0.35 mm.
For horizontal sync frequencies below 58 kHz:
Inside a circle with a diameter equal to the height of the active screen £
0.4 mm. Elsewhere inside the active screen area £ 0.45 mm.
445N
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