6-4
2. CRT
[A] Screen and Faceplate Blemishes
1. Measuring conditions
1-1. Defect, when tube is in operation, shall be observe under the following conditions:
9,300 K +27 M.P.C.D.(or 6,550 K + 7 M.P.C.D.) and white raster of 34 cd/m
2
(10 ft-L) at the center of the
screen or component monochromatic raster used to generate raster above.
Ambient light shall be approx. 10 Lx.
1-2. Observe the defect, when tube is not in operation, under the light of approx. 200 Lx, measured at the
faceplate surface.
1-3. Observe at a distance of 45cm from the screen.
1-4. Observe white and individual field, and appearance respectively.
2. Zone division
Screen can be divided into 2 zones as follows.
Zone A: Internal rectangle of 395mm by horizontal and 295mm by vertical of which the screen center is located
in the center.
Zone B: Area outside the rectangle.
3. Defect criteria
3-1. Defective phosphor screen
1) Distance between defects (Minimum distance)
2) Mean defect diameter
Mean diameter = (shorter diameter + longer diameter) / 2
3) Defect criteria (acceptable defect amount)
a) Dark spot, Blocked aparture
Mean diameter (mm) A B A + B Shortest distance
0.51 ~ 0 0 0 -
0.31 ~ 0.50 0 0 0 -
0.15 ~ 0.30 6 (note 1) 6 (note 1) 10 (note 1) 10mm
b) Discoloration, Stain, Missing phospher, etc.
Mean diameter(mm) A B A + B Shortest distance
0.51 ~ 0.75 0 1 - 20mm
0.15 ~ 0.50 2 3 - 20mm
Note 1: This criteria is applied to each color respectively.
Note 2: Ignore all defect regarding 1 trio of phosphor stripe corresponding to the last slit.
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