Image Size; Linearity; Geometrical Distortion; Straightness Of Line Segment - Nokia 445PRO Service Manual

6.6 Image size

Display size is defined as the width and height of the display using the active raster, not including
the border.
Measurement:
Full white field brightness set to 100 nits (29.2 Ft ---L).
Cross---hatch test pattern.
The width and the height are measured at the center of the screen.
Requirements:
Nominal size:
Width = 393 ± 6 mm
Height = 293 ± 3 mm
Over the full range of operating temperature, the size shall not change more than one percent.

6.7 Linearity

Cross---hatch test pattern (16 x 12 cells). Brightness control set so that the background raster is just
extinguished and the contrast control is set to maximum.
The limits for vertical or horizontal non---linearities are 5 % for adjacent cells and 8 % for overall lin-
earity. The method of calculating linearity is:
[ (max---min)/max ]*100 < 8 %
The measurements are done along the vertical and horizontal center lines of the screen.

6.8 Geometrical distortion

The distance between bezel and active screen edge shall not vary more than
1.5 mm on vertical lines and not more than 2.0 mm on horizontal lines (excluding the tilt adjust-
ment).

6.9 Straightness of line segment

Definition:
For any segment of an edge of the active picture the deviation from be-
ing straight is defined as the distance from the straight line formed by
connecting the end points of the segment under test to the point on the
line segment furthest from that construction.
Measurement:
The deviation is to be measured perpendicular to the constructed line.
deviation = a---b
% deviation = (a---b/l) x 100 %
Requirements:
For line segments less than 50 mm the maximum allowed deviation is 0.8mm.
0 --- 50 :max. dev. 0.5 mm
50 --- 200 :max. dev. 1.0 --- 2.0 mm
200 --- :max dev. 2.0 mm
This must be valid for vertical and horizontal lines.
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