MILDTL28803C
4.6.3.2.2 Contrast ratio with alternate segments illuminated. The odd numbered segments shall be fully
illuminated and the even numbered segments shall be non-illuminated. At least two readings shall be taken at
equidistant points on each segment. The luminance readings of illuminated segments shall be averaged, and the
readings of the non-illuminated segments shall be averaged.
The contrast ratio shall be determined by measuring B2 (brightness of illuminated segment) and B3 (brightness of
non-illuminated segment) and calculating:
B2 B3
C =
B3
4.6.3.3 Field of view (see 3.5.3.3). The displays shall be mounted in a horizontal position with the character(s)
lighted. The lens face shall be viewed from a distance of 3 feet (0.91 m), unless otherwise specified (see 3.1), all
angles up to 45 degrees to a line perpendicular to the viewing surface.
4.6.3.4 Luminance (see 3.5.3.4). All luminance measurements shall be taken in completely dark surroundings and
all segments shall be illuminated. All readings shall be point readings and averaged. Luminance readings shall be
taken by a calibrated photoelectric photometer. The spot size used shall be no smaller than 50 percent or no larger
than 80 percent of the segment dot size or line width. With the photometer element fully illuminated, at least two
readings shall be taken at equidistant points along each illuminated segment of the character.
4.6.4 Physical and mechanical tests.
4.6.4.1 Mechanical endurance (see 3.5.4.1) (applicable if cable to plug in units only). Displays shall be
subjected to 150 insertions and removals, either manually or automatically.
4.6.4.2 Resistance to soldering heat (when specified, see 3.5.4.2)(see 3.1 and 6.2). DispIays shall be tested in
accordance with method 210 of MILSTD202, test condition B.
4.6.4.3 Solderability (see 3.5.4.3) (applicable to solderable terminals). Solder type terminations shall be tested in
accordance with method 208 of MILSTD202. The following details and exceptions shall apply:
a.
Number of terminations to be tested: Two terminals per unit.
b.
Examination of termination: Terminals shall be examined for solder coating, pinholes or rough spots, or
whether concentrated in one area.
4.6.4.4 Terminal strength (see 3.5.4.4). Displays shall be mounted by their normal mounting means. No terminals
shall be tested in more than one direction. Terminals shall be tested in accordance with method 211 of
MILSTD202. The following details and exceptions shall apply:
a.
Test condition: As specified (see 3.1).
b.
Applied force: As specified (see 3.1).
c.
Following the test, displays shall be examined for movement or loosening of parts, visible permanent set or
evidence of mechanical damage.
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